# Bangladesh National Building Code (BNBC) 2020
Source: https://docs.sayed.app/bnbc/index
Minimum standards for design, construction, use, occupancy, and maintenance of buildings in Bangladesh.
The Bangladesh National Building Code (BNBC) 2020 was made under section 18A of the Building Construction Act, 1952 (Act No. II of 1953), repealing the Bangladesh National Building Code, 2006. It was published by the Ministry of Housing and Public Works as S.R.O. No. 55-Law/2020, and gazetted on 11 February 2021.
Its purpose is to establish minimum standards for the design, construction, quality of materials, use and occupancy, location, and maintenance of all buildings in Bangladesh, in order to safeguard life, limb, health, property, and public welfare.
## Parts
Title, purpose, and scope of the Code; definitions; abbreviations.
Applicability, the Building Regulatory Authority, permits, and inspections.
Occupancy classification, fire-resistance classification, and energy efficiency.
Means of egress and fire detection and extinguishing systems.
Scope, definitions, and standards for building materials.
Loads, soils and foundations, and design of concrete, masonry, and steel structures.
## Citing this Code
Sections are numbered per part and chapter as in the gazette (for example, Sec 3.8.4 refers to Part II, Chapter 3, Section 3.8.4). Use those numbers, not page numbers, when citing a provision: they're stable across this site's formatting.
# Chapter 1: Title, Purpose, Scope, Etc
Source: https://docs.sayed.app/bnbc/part-1-administration/chapter-1-title-purpose-scope-etc
## 1. Title and commencement
(1) This Code may be called the Bangladesh National Building Code (BNBC) 2020.
(2) It shall come into force at once.
## 2. Purpose
(1) The purpose of this Code is to establish minimum standards for design, construction, quality of materials, use and occupancy, location and maintenance of all buildings within Bangladesh in order to safeguard, within achievable limits, life, limb, health, property and public welfare.
(2) The installation and use of certain equipment, services and appurtenances related, connected or attached to such buildings are also regulated herein to achieve the same purpose.
(3) The expressed intent of this Code is to ensure public safety, health and general welfare insofar as they are affected by the construction, alteration, repair, removal, demolition, use or occupancy of buildings, structures or premises, through structural strength, stability, means of egress, safety from fire and other hazards, sanitation, light and ventilation.
## 3. Scope
(1) The provisions of this Code shall apply to the design, construction, use or occupancy, alteration, moving, demolition and repair of any building or structure and to any appurtenances installed therein or connected or attached thereto, except such matters as are otherwise provided for in other laws controlling and regulating buildings.
(2) If for any case different sections of this Code provide different specifications for materials, methods of design or construction, or other requirements, the most restrictive specification shall govern.
(3) In case of any conflict between a general requirement and a specific requirement, the specific requirement shall prevail.
(4) Unless otherwise explicitly stated in this Code, all references to part, chapter or section numbers or to provisions not specifically identified by number, shall be construed to refer to such part, chapter, section or provision of this Code.
(5) References made to a section without mentioning a part shall be construed to refer to that section of the part in which the reference is made.
(6) The provisions of any appendix in this Code shall not be mandatory unless they are referred to as such in any section of the Code or they are specifically adopted by any regulation.
(7) Inspection conducted or permission granted for any building or plan of building, under the provisions of this Code, shall not be construed as a warranty of the physical condition of such building or the adequacy of such plan.
(8) Neither the Authority nor any employee thereof shall be liable for damages or any defect or hazardous or illegal condition or inadequacy in such building or plan, nor for any failure of any component of such building which may occur subsequent to such inspection or granting of permission under the provisions of the Code.
## 4. Existing buildings
(1) Buildings which are in existence on the date of commencement of this Code may have their use or occupancy continued without undergoing any alteration, abandonment or removal unless in the opinion of the Authority such continued use is hazardous to life and property and provided such use or occupancy was legal on the date of commencement of this Code.
(2) Buildings approved before commencement of this Code and compliant under the repealed Code may continue to be used or occupied unless any deviation is made thereafter or any deterioration has rendered the building unsafe in the opinion of the Authority.
(3) Additions, alterations, modifications or repair to an existing building may be made without requiring the existing building to comply with all the requirements of this Code, provided the additions, alterations, modifications or repairs conform to that required for a new building and such additions or alterations shall not be permitted when the existing building is not in full compliance with the provisions of this Code except when the addition or alteration will result in the existing building or structure being no more hazardous based on life safety, fire safety and sanitation than it was before the addition or alteration was undertaken.
(4) Any building together with the new additions shall not exceed the height, number of storeys and area specified in this Code for new buildings having the relevant occupancy and type of construction.
(5) Non-structural alterations or repairs to an existing building or structure which do not adversely affect any structural member, nor reduce the strength of any part of the building or structure to result in an unsafe condition shall be made with materials and components having the required fire resistance.
(6) Change in use or occupancy in an existing building may be made when such change complies with the requirements of this Code for a new building and provided such change does not render any part or the whole of the affected building or structure any more hazardous based on life safety, fire safety and sanitation than it was before such change was effected.
## 5. Historic or architecturally valuable buildings
A building or structure which has been designated by official action as having special historical or archaeological interest, or a building or structure identified by a legally constituted authority as being architecturally valuable, may be undertaken for repairs, alterations and additions necessary for its preservation, restoration, rehabilitation or continued use, provided:
* (a) the proposed repair, alteration or addition to buildings of historical or archaeological significance is approved by the legally constituted authority, such as the Department of Archaeology;
* (b) the proposed repair, alteration or addition to buildings of architectural value does not impair the aesthetic quality and architectural character of such buildings; and
* (c) the restored building or structure will be no more hazardous, if any, based on life safety, fire safety and sanitation than the existing building.
# Chapter 2: Definitions
Source: https://docs.sayed.app/bnbc/part-1-administration/chapter-2-definitions
## 6. Definitions
In this Code, unless there is anything repugnant in the subject or context:
| Term | Definition |
| ---------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **ACCESSORY USE** | means any use subordinate to the major use which is normally incidental to the major use. |
| **ALTERATION** | means any change, addition or modification in construction such as structural, dimensional, or any removal of any part of a building or any change to or closing of any required means of ingress or egress or a change to the fixtures or equipment or any change in land use or occupancy or use. |
| **APPLICANT** | means a person, a firm, a company, a corporation, or a government, semi-government or non-government agency who intends to undertake any work regulated by this Code and who has filed an application to the Building Official for this purpose in a form prescribed in the Code. |
| **APPROVED** | means approved by the Authority. |
| **APPROVED PLAN** | means the set of plans, designs and specifications of building submitted to the Authority as per provision of this Code and duly approved and sanctioned by the Authority. |
| **ARCHITECT** | means a person who has a Bachelor Degree in Architecture and is a member of the Institute of Architects, Bangladesh (IAB). |
| **AUTHORITY** | means the Bangladesh Building Regulatory Authority. |
| **AUTHORIZED OFFICER** | means BUILDING OFFICIAL. |
| **BASEMENT** | means a floor of a building more than 50 percent of which is situated at a depth of 1 m or more below crown of the main entry road. |
| **BUILDING** | means any permanent or semi-permanent structure which is constructed or erected for human habitation or for any other purpose and includes but not limited to the foundation, plinth, walls, floors, roofs, stairs, chimneys, fixed platform, verandah, balcony, cornice, projections, extensions, annexes etc. The term building will also include the sanitary, plumbing, electrical, HVAC, appurtenances and all other building service installations which are constructed or erected as an integral part of a building. |
| **BUILDING LINE** | means the line up to which the plinth of a building may lawfully extend. Also known as SETBACK LINE. |
| **BUILDING OFFICIAL** | means a person who is the jurisdictional administrator of this Code appointed by the Authority. |
| **COMMITTEE** | means a Building Construction Committee constituted for any area in the prescribed manner, if necessary. |
| **CONSTRUCT** | means ERECT. |
| **CONVERSION** | means the change in occupancy or premises to any occupancy or use requiring new occupancy permit. |
| **COVERED AREA** | means the ground area above the plinth level which is covered by a building structure. The covered area of a building shall exclude gardens, wells, cornice, sunshade, pergola, septic tank, soak well, unpaved uncovered water body, fountains, drainage structures, boundary wall, gates, porch, uncovered staircase, watchman's cabin, detached pump house, garbage chutes and other uncovered utility structures. |
| **DEVELOPMENT** | means carrying out construction of buildings, engineering, mining or other operations in, or over or under land or water. Includes re-development and layout and subdivision of any land. 'To develop' and other grammatical variations shall be interpreted accordingly. |
| **DIPLOMA ARCHITECT** | means a person who has a Diploma in Architecture from any recognized Polytechnic or Technical Institute and is a member of the Institution of Diploma Engineers, Bangladesh (IDEB). |
| **DIPLOMA ENGINEER** | means a person who has a Diploma in Engineering from any recognized Polytechnic or Technical Institute and is a member of the Institution of Diploma Engineers, Bangladesh (IDEB). |
| **DRAIN** | means a conduit or channel for conveying water, sewage, or other waste liquid for subsequent disposal. |
| **DRAINAGE** | means the disposal of any liquid with a system meant for this purpose. |
| **ENGINEER** | means a person who has a Bachelor Degree in Engineering and is a member of the Institution of Engineers, Bangladesh (IEB). |
| **ERECT** | means to erect a new building or re-erect an existing building or to convert a building from one occupancy to another. Also known as CONSTRUCT. |
| **FORMATION LEVEL** | means finished ground level of a plot. For hilly areas formation levels shall be the gradient of the plot surface. |
| **GEOTECHNICAL ENGINEER** | means engineer with Masters degree in geotechnical engineering having at least 2 (two) years of experience in geotechnical design/construction or graduate in civil engineering/engineering geology having 10 (ten) years of experience in geotechnical design/construction. |
| **ENGINEERING GEOLOGIST** | means a person having a postgraduate degree in engineering geology and having 2 years of experience in geotechnical exploration and interpretation. |
| **GOVERNMENT** | means the government of the People's Republic of Bangladesh. |
| **GRADE** | means the lowest point of elevation of the finished surface of the ground, pavement or footpath within the area between the building and the property line or a line 1.5 m from the building whichever is nearer the building. |
| **HEIGHT OF BUILDING** | means the vertical distance from a reference datum to the highest point of the building which includes all building appurtenances like overhead water tank, machine room, communication tower etc. The reference datum shall be the elevation of the nearest footpath or the elevation of the nearest road or street or public way at its centre line, whichever is higher. |
| **HIGH RISE BUILDING** | means any building which is more than 10-storey or 33 m high from reference datum. Building appurtenances like overhead water tank, machine room, communication tower etc. will not be considered in determining the height. |
| **OCCUPANCY or USE GROUP** | means the purpose for which a building or a part thereof is used or intended to be used. |
| **OCCUPANCY, MAJOR** | means the major or principal occupancy of a building or a part thereof which has attached to it subsidiary occupancy or occupancies contingent upon it. |
| **OCCUPIER** | means a person paying or liable to pay rent or any portion of rent of a building in respect of which the word is used, or compensation or premium on account of occupation of such building and also a rent-free tenant. Does not include a lodger and the words 'occupancy' and 'occupation' do not refer to the lodger. In such cases, the owner himself or herself is living in his or her own building, he or she shall be deemed to be the occupier thereof. |
| **OWNER OF A BUILDING** | means the person, organization or agency at whose expenses the building is constructed or who has the right to transfer the same and includes his or her heirs, assignees and legal representatives, and a mortgagee in possession. |
| **PERMIT** | means a written document or certificate issued by the Authority for carrying out a specific activity under the provisions of this Code. |
| **PLANNER** | means a person who has a Bachelor or a Postgraduate Degree in Planning and is a member of the Bangladesh Institute of Planners (BIP). |
| **PLINTH AREA** | means the elements from the building bases which are exposed above the formation level to form a covered floor area by joining the peripheral points of the elements which are intersected at finished floor plane at the height of plinth level. |
| **PLINTH LEVEL** | means height of a covered finished floor which is not more than 1 m above the formation level nor 1.85 m from the crown of adjacent road level. |
| **PLOT** | means SITE. |
| **PLUMBING ENGINEER** | means an Engineer (Civil/Mechanical) who has experience in the field of plumbing or sanitation. |
| **PUBLIC WAY** | means ROAD. |
| **RELIABLE LITERATURE** | means RELIABLE REFERENCE. |
| **RELIABLE REFERENCE** | means reference materials such as published article, codes, standards or other material judged to be reliable by the professional users and specialists in the subject concerned. This may also be referred to as RELIABLE LITERATURE. |
| **ROAD** | means a thoroughfare or public way which has been dedicated or deeded to the public for public use and also known as STREET. |
| **ROAD LINE** | means a line defining the side limits of a road. |
| **ROOM HEIGHT** | means the clear head room between the finished floor surface and the finished ceiling surface or the underside of the joists or beams, whichever is lower. |
| **SANCTIONED PLAN** | means the set of plans, design and specifications of a building submitted to the Authority as per provision of this Code and duly approved and sanctioned by the Authority. |
| **SERVICE ROAD** | means a road or lane provided at the rear or side of a plot for service purposes. |
| **SETBACK LINE** | means BUILDING LINE. |
| **SITE** | means a piece or parcel of land on which a building is intended to be or has already been constructed and also known as PLOT. |
| **SPECIALIST** | means a professional who by education, research, practice and experience specializes in a particular branch of a broader discipline and is generally judged to be so by the professional body in the relevant discipline. |
| **STOREY** | means the portion of a structure between tops of two successive finished floor surfaces and for the topmost storey, from surface of the finished floor of topmost floor to the top of the roof above. |
| **STOREY, FIRST** | means the lowest storey in a building which qualifies as a storey as defined herein; for a building with a basement, it is the storey just above the basements. |
| **STREET** | means ROAD. |
| **STREET LEVEL** | means the elevation of the centre line of any road or street which a plot fronts. |
| **STREET LINE** | means ROAD LINE. |
| **SUPERVISOR, CONSTRUCTION** | means an Architect or Engineer or Diploma Architect or Diploma Engineer having experience in supervision of construction works. |
| **UNSAFE BUILDING** | means a building which, in the opinion of the Building Official, is structurally unsafe, or insanitary, or lacks proper means of ingress or egress, or which constitutes a hazard to life or property. |
# Chapter 3: Abbreviations
Source: https://docs.sayed.app/bnbc/part-1-administration/chapter-3-abbreviations
## 7. Abbreviations of names and words
(1) Names of institutions, organizations and professional societies referred to in this Code are listed below in an alphabetical order, namely:
| Abbreviation | Name |
| ------------ | ----------------------------------------------------------------------------------------------------------------------------------------------- |
| **ACI** | American Concrete Institute; Box 19150, Redford Station, Detroit, MI 48219, USA. |
| **AISC** | American Institute of Steel Construction, Inc.; 400 North Michigan Avenue, Chicago, IL 60611, USA. |
| **AISE** | Association of Iron and Steel Engineers; Suite 2350, Three Gateway Center, Pittsburgh, PA 15222, USA. |
| **AISI** | American Iron and Steel Institute; Suite 300, 1133 15th Street N.W., Washington, DC 20005, USA. |
| **ANSI** | American National Standards Institute; 1430 Broadway, New York, NY 10018, USA. |
| **ASHRAE** | American Society of Heating, Refrigerating and Air-conditioning Engineers, Inc.; 345 East 47th Street, New York, NY 10017, USA. |
| **ASME** | American Society of Mechanical Engineers; United Engineering Centre, 345 East 47th Street, New York, NY 10017, USA. |
| **ASTM** | American Society for Testing and Materials; 1916 Race Street, Philadelphia, PA 19103, USA. |
| **AWS** | American Welding Society; 550 N.W. LeJeune Rd., P.O. Box 351040, Miami, FL 33135, USA. |
| **BIP** | Bangladesh Institute of Planners, Planner’s Tower (Level-7), 13/A, Bir Uttam C.R. Datta (Sonargaon) Road, Bangla Motor, Dhaka-1000, Bangladesh. |
| **BOCA** | Building Officials and Code Administrators International Inc.; 1313 East 60th Street, Chicago, IL 60637, USA. |
| **BPDB** | Bangladesh Power Development Board; WAPDA Building, Motijheel Commercial Area, Dhaka-1000, Bangladesh. |
| **BSI** | British Standards Institution; 2 Park Street, London W1A 2BS, UK. |
| **BSTI** | Bangladesh Standards and Testing Institution; 116A Tejgaon Industrial Area, Dhaka-1208, Bangladesh. |
| **BWDB** | Bangladesh Water Development Board; WAPDA Building, Motijheel Commercial Area, Dhaka-1000, Bangladesh. |
| **CDA** | Chittagong Development Authority; Station Road, Chittagong, Bangladesh. |
| **CGSM** | Canadian General Standards Board; Technical Information Unit, Ottawa, CANADA K1A 1G6. |
| **DOA** | Department of Architecture; Sthapatya Bhaban, Shahid Capt. Mansur Ali Sarani, Segunbagicha, Dhaka-1000, Bangladesh. |
| **DPHE** | Department of Public Health Engineering; DPHE Bhaban, 14, Shaheed Captain Mansur Ali Sarani, Kakrail, Dhaka-1000, Bangladesh. |
| **EED** | Education Engineering Department; Shikkha Bhaban, Dhaka-1000, Bangladesh. |
| **HED** | Health Engineering Department; Ministry of Health and Family Welfare, 105-106, Motijheel C/A, Dhaka-1000, Bangladesh. |
| **FM** | Factory Manual; Standards Laboratories Department, 1151 Boston Providence Turnpike, Norwood, MA 02062, USA. |
| **FSCD** | Fire Service and Civil Defence, Kazi Alauddin Road, Dhaka-1000, Bangladesh. |
| **HBRI** | Housing and Building Research Institute, 120/3, Darus-Salam, Mirpur, Dhaka, Bangladesh. |
| **IAB** | Institute of Architects Bangladesh, Plot-11, Block-E, Road-7, Sher-e- Bangla Nagar, Agargaon, Dhaka. |
| **IEB** | The Institution of Engineers, Bangladesh, Ramna, Dhaka-1000. |
| **IDEB** | Institution of Diploma Engineers, Bangladesh, IDEB Bhaban, 160/A, Kakrail VIP Road, Dhaka-1000. |
| **ICBO** | International Conference of Building Officials, 5360 South Workman Mill Road, Whittier, CA 90601, USA. |
| **ISO** | International Organization for Standardization, 1, Rue de Varembé, Case Postal 56, CH-1211, Genève 20, Switzerland. |
| **ISSMFE** | International Society of Soil Mechanics and Foundation Engineering, University Engineering Department, Trumpington St, Cambridge CB21PZ, UK. |
| **KDA** | Khulna Development Authority, Shib Bari Crossing, Khulna-9100, Bangladesh. |
| **LGED** | Local Government Engineering Department, LGED Bhaban, Sher-e- Bangla Nagar, Agargaon, Dhaka-1207. Bangladesh. |
| **NFPA** | National Fire Protection Association, Batterymarch Park, Quincy, MA 02269, USA. |
| **NHA** | National Housing Authority, Grihayan Bhaban, 82, Segunbagicha, Dhaka, Bangladesh. |
| **PWD** | Public Works Department, Purto Bhaban, Shahid Capt. Mansur Ali Sarani, Segunbagicha; Dhaka-1000, Bangladesh. |
| **RAJUK** | Rajdhani Unnayan Kartripakkha, Rajuk Avenue, Motijheel, Dhaka-1000, Bangladesh. |
| **RCSC** | Research Council on Structural Connections of the Engineering Foundation, American Institute of Steel Construction (AISC). |
| **RDA** | Rajshahi Development Authority, Rajshahi-6203, Bangladesh. |
| **RMA** | Rubber Manufacturing Association, 1400 K Street N.W., Washington, DC 20005, USA. |
| **SBCCI** | Southern Building Code Congress International, 3617 8th Ave, S. Birmingham, AL 35222, USA. |
| **SMACNA** | Sheet Metal and Air Conditioning Contractors' National Association, 8224 Old Courthouse Road, Tysons Corner, Vienna, VA 22180, USA. |
| **SPRI** | Single Ply Roofing Institute, 104 Wilmont Road, Suite 201, Deerfield, IL 600015-5195, USA. |
| **UDD** | Urban Development Directorate, Ministry of Housing and Public Works, 82, Segunbagicha, Dhaka-1000, Bangladesh. |
| **UL** | Underwriters Laboratories Inc., 207 East Ohio Street, Chicago, IL 60611, USA. |
(2) The abbreviations of words used in this Code are listed below in an alphabetical order. Abbreviations not explicitly defined herein below shall be construed to have their usual meaning as the context implies.
| Abbreviation | Meaning |
| ------------ | ------------------------------------------------------------ |
| **BDS** | Bangladesh Standards; published by the BSTI |
| **BNBC** | Bangladesh National Building Code; published by HBRI |
| **BS** | British Standard; published by the BSI |
| **CBF** | Concentric Braced Frame |
| **CFC** | Chlorofluorocarbon |
| **CGI** | Corrugated Galvanized Iron |
| **CWPC** | Cold Drawn Low Carbon Wire Prestressed Concrete |
| **DCP** | Dry Chemical Powder (fire extinguisher) |
| **DDT** | Dichlorodiphenyltrichloroethane |
| **DPC** | Damp-proof Course |
| **EBF** | Eccentric Braced Frame |
| **FAR** | Floor Area Ratio |
| **FM** | Fineness Modulus |
| **FPA** | Flood Prone Area |
| **GI** | Galvanized Iron |
| **IBC** | International Building Code |
| **IMRF** | Intermediate Moment Resisting Frame |
| **IS** | Indian Standard; published by the Bureau of Indian Standards |
| **LFD** | Load Factor Design |
| **LPG** | Liquefied Petroleum Gas |
| **MCSP** | Multipurpose Cyclone Shelter Program |
| **OMRF** | Ordinary Moment Resisting Frame |
| **RC** | Reinforced Concrete |
| **RS** | Rolled Steel |
| **RSJ** | Rolled Steel Joist |
| **SMRF** | Special Moment Resisting Frame |
| **SPA** | Surge Prone Area |
| **SRSS** | Square Root of the Sum of the Squares |
| **UBC** | Uniform Building Code; published by the ICBO |
| **WSD** | Working Stress Design |
| **cps** | Cycles per second |
# Part I: Administration
Source: https://docs.sayed.app/bnbc/part-1-administration/index
Title, purpose, and scope of the Code; definitions; and abbreviations used throughout BNBC 2020.
Part I sets out what the Code is for, who and what it applies to, and the terms and abbreviations used in the rest of the Code.
What the Code is called, its intent, its scope, and how it treats existing and historic buildings.
Defined terms used throughout the Code.
Referenced institutions and abbreviations of words used in the Code.
# Chapter 1: Purpose and Applicability
Source: https://docs.sayed.app/bnbc/part-2-development-control/chapter-1-purpose-and-applicability
## 8. Purpose
The purpose of this Part is to relate the provisions of the Code to different documents for administration and enforcement of the Code and all legal issues shall be referred to the Building Construction Act, 1952.
## 9. Applicability
The requirements of this Code shall be complied within any construction, addition, alteration or repair, use and occupancy, location, maintenance, demolition and removal of a building or structure or any appurtenances connected or attached to it as set forth herein below:
* (a) **Construction:** For construction of a new building, the provisions of this Code shall apply to its design and construction;
* (b) **Removal:** For removal of any portion or the whole of a building, the provisions of this Code shall apply to all parts of the building whether removed or not;
* (c) **Demolition:** For dismantling or demolition of any part or the whole of a building, the provisions of this Code shall apply to any remaining portion and to the work involved in the dismantling or demolition process;
* (d) **Alteration:** For alteration of a building, the provisions of this Code shall apply to the whole building whether existing or new. If the portion of the building to which the alteration is made is completely self-contained with respect to the facilities and safety measures required by this Code, the provisions of this Code shall apply only to that portion and not to the whole building.
* (e) **Maintenance:** Maintenance work shall be undertaken for all new and existing buildings and all parts thereof to continue their compliance with the provisions of this Code. All devices, equipment and safeguards installed as per the requirements of this Code shall be maintained in conformity with the edition of the Code under which installed. The owner of the building or his designated agent shall at all times be responsible for the safe and sanitary maintenance of the building or structure, its means of egress facilities and the safety devices, equipment and services installed therein. The Authorized Officer or his delegated persons as described in relevant documents mentioned in Chapter 2 may cause re-inspection of a building to determine its continued compliance with this Section.
* (f) **Repair:** Application or notice to the Authority administering the Code is not necessary for ordinary repairs to buildings or structures, provided such repairs do not involve the cutting away of any wall or portion thereof, the removal or cutting of any structural or bearing element, the removal or alteration of any required means of egress, or the rearrangement of any parts of a structure affecting the access and exit facilities. All works involving addition to, alteration or change of use of any building or structure shall conform to the requirements set forth in Part 9 of this Code.
* (g) **Land Development:** For development of a land for construction of a building, the provisions of this Code shall apply to the entire development work. For land development purposes the following laws shall also be applicable:
* (i) Building Construction Act 1952;
* (ii) Private Residential Land Development Rules 2004;
* (iii) Natural Water Body Protection and Preservation of Open Space and Playground Act 2000.
# Chapter 2: Establishment of Authority, Etc
Source: https://docs.sayed.app/bnbc/part-2-development-control/chapter-2-establishment-of-authority-etc
## 10. Establishment of Authority
The Government may, with the approval of the Ministry of Public Administration, Finance Division and other relevant Ministries and Divisions, by a notification in the official Gazette, establish the Bangladesh Building Regulatory Authority (BBRA).
## 11. Head office of the Authority
The head office of the Authority shall be in Dhaka.
## 12. Constitution of Authority
(1) The Authority shall consist of the following 5 (five) members, namely:-
* (a) a civil engineer having professional experience of 30 years in design/ construction/teaching/research related to building;
* (b) an architect having professional experience of 30 years in design/ construction/ teaching/ research related to building;
* (c) a planner having professional experience of 30 years in planning/ teaching/research related to building;
* (d) a judge or legal practitioner having professional experience of 30 years in law including the qualification for appointment of a judge of the High Court Division;
* (e) a person having professional experience of 30 years in Bangladesh Civil Service.
(2) The Government shall appoint the members of the Authority and they shall hold office for a period of 3 (three) years.
(3) The Government shall nominate one of the members as the Chairman of the Authority.
## 13. Responsibilities of the Authority
The Authority shall
* (a) be the organization responsible for establishing regulatory framework for building design and construction with efficient and effective compliance mechanism;
* (b) develop building check and control procedure for ensuring high degree of regulatory compliance in planning and the Code requirements and reduce information asymmetry between the end user (building occupant, home owner) and seller (developers, builders);
* (c) streamline and improve transparency through dissemination of information related to built environment including detail land use plan, regulations on safety, water and environmental conservation, health, energy efficiency and urban planning requirements through print and digital media including its website;
* (d) develop an effective licensing system, jointly with the professional bodies by forming a National Council for Licensing of Building Professionals (NCLBP) for conducting examinations for the members of those respective professional bodies;
* (e) update the requirements of building permit and inspection procedure as per this Code;
* (f) require the owner of an existing or under construction high risk building, having major impacts on public safety for inhabitants within and near the building, to carry out review of design and construction by licensed professionals acceptable to the Authority;
* (g) introduce IT based automated procedure for permits and online information system to enable the applicants to track the progress of the permitting process;
* (h) establish an independent quasi-judicial dispute-resolution body that can make binding decisions in disputes between practitioners, developers, stakeholders and permitting authorities on matters related to interpretation of the Code or sufficiency of compliance, which cannot be appealed except to the High Court Division on matters of law;
* (i) recommend punitive and other measures against developers and professionals for violation of the Code and safety measures;
* (j) take measures for updating of the Code in light of research, improved building design and construction technique, availability of new products and technology;
* (k) advise the Government on policy and administration of building regulations including capacity development;
* (l) take up matters from time to time which the Authority deems necessary.
## 14. Office of the Building Officials, etc
(1) The Authority shall designate specific geographical jurisdiction as the Office of the Building Official.
(2) The Office of the Building Official shall be established at various local or regional development area or local government levels.
(3) The Authority may, in order to proper functioning of it, subject to the Organogram approved by the Government and having required qualifications, appoint such numbers of Building Officials, technical assistants, inspectors and other employees as required.
(4) The administrative and operational chief of the Code enforcing office shall be designated as the Building Official who shall act on behalf of the Authority.
(5) The Building Official may designated an employee or employees who shall carry out the specified duty and exercise the specified power of the Building Official.
## 15. Building Construction Committee
(1) The Building Official shall exercise through a Building Construction Committee comprising four members excluding Building Official.
(2) Building Construction Committee shall consist of one architect, one civil engineer, one town planner and representative from concerned body.
(3) Building Official shall work as ex-officio member-secretary of the Committee.
## 16. Qualifications of Building Official
The person to be designated as the Building Official shall be at least an architect, a civil engineer or a town planner in addition to fulfilling any other requirement of the Authority.
## 17. Administrative jurisdiction of Building Official
(1) The areas delineated below in Table 2.2.1 shall be under the jurisdiction of the Building Officials located in the offices/authorities mentioned in the right hand column:
**Table 2.2.1: Jurisdiction of Building Officials of Designated Offices/Authorities**
| **Sl.** | **Area** | **Authority** |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------- |
| 1 | Areas falling under the master plan control of Rajdhani
Unnayan Kartipokhkha (RAJUK) | RAJUK |
| 2 | Areas falling under the master plan control of
Chittagong Development Authority (CDA) | CDA |
| 3 | Areas falling under the master plan control of Rajshahi
Development Authority (RDA) | RDA |
| 4 | Areas falling under the master plan control of Khulna
Development Authority (KDA) | KDA |
| 5 | Areas falling under the master plan control of any
Development Authority to be established in future | Relevant
development
authority |
| 6 | Areas falling under the geographical jurisdiction of any
City Corporation where no Development Authority exists | Relevant city
corporation |
| 7 | Areas falling under the geographical jurisdiction of any
Municipality where no Development Authority exists | Relevant
municipality |
| 8 | Areas not falling under any of the above | Office of The
Executive Engineer
Public Works
Department (PWD) |
| 9 | Special areas, if any | To be declared by the
government as and
when necessary |
| (2) There may be as many Building Officials as required depending upon the area of jurisdiction, but every Building Official shall be in charge of an independent and well demarcated area. | | |
## 18. Merging the Jurisdictions under small local bodies
Small local bodies like Pourashavas, Upazila, Union Parishad, located outside the larger city municipalities and having insufficient funds for individually carrying out the task of the Code enforcing agency may jointly appoint or designate, with the approval of the Authority, a Building Official who shall have a jurisdiction over the combined area of jurisdiction of the concerned local bodies.
## 19. Restrictions on the Building Official
(1) The Building Official or any employee designated by him in this behalf shall not in any way, directly or indirectly, be engaged in planning, design, construction, repair, maintenance, modification or alteration of a building, certification of any work or materials, supply of materials, labor, equipment or appliances or any other work regulated by the provisions of this Code.
(2) The Building Official or such designated employee shall not be interested in business, either directly or indirectly, as planner, engineer, architect, builder or supplier or in any other private business transaction or activity within the jurisdiction of the Authority which conflicts with his official duties or with the interest of the Code enforcing agency.
(3) If any Building Official or designated employee violates the restrictions, he shall be liable to punishment as per service rule of the government.
## 20. Damage Suit
(1) In the process of discharging the official duties as required and permitted by the Code, the Building Official or any employee shall not be personally liable for any damage that may be caused to any person or property.
(2) Any suit filed against the Building Official or any employee because of an act performed by him in the official discharge of his duties and under the provisions of the Code shall be defended by the legal representative of the Authority until the final decision of the proceedings.
(3) In no case shall the Building Official or any employee be liable for costs in any legal action, suit, or defense proceedings that may be filed in pursuance of the provisions of the Code.
## 21. Powers and duties of the Building Official
(1) The Building Official shall be authorized to enforce all the provisions of this Code and for such purposes the Building Official shall have the power of a law enforcing officer.
(2) Applications shall be made in writing to the Building Official for any erection, construction, addition, alteration, modification, repair, improvement, removal, conversion, change of occupancy, and demolition of any building or structure regulated by this Code.
(3) The Building Official shall receive such applications, examine the premises, enforce compliance with this Code and issue permits for the intended work.
(4) All necessary notices and orders to correct illegal or unsafe conditions, to require the specified safeguards during construction, to require adequate access and exit facilities in existing buildings and to ensure compliance with all the requirements of safety, health and general welfare of the public as included in this Code shall be issued by the Building Official.
(5) The Building Official may enter a building or premises at reasonable times to inspect or to perform the duties imposed by this Code if:
* (a) it is necessary to make an inspection to enforce the provisions of this Code; or
* (b) he has reasonable cause to believe that a condition contrary to or in violation of this Code exists making the building or the premises unsafe, hazardous or dangerous.
(6) If the building or premises is occupied, the Building Official shall present credentials to the occupant and request entry.
(7) If the building or premises is unoccupied, the Building Official shall first make a reasonable effort to locate the owner or any other person having charge or control of the building or premises and request entry.
(8) If entry into the building or premises is refused or the owner of the unoccupied building or premises cannot be located, the Building Official shall secure entry as provided by the law.
(9) The Building Official or an employee designated by him in this behalf shall inspect all construction or work for which a permit is required or he may accept reports of inspection by a licensed engineer, architect or planner provided he satisfies the requirements of Table 2.3.4 and may disapprove the report showing specific reason for disapproval.
(10) The work or construction to be inspected shall remain accessible and exposed for inspection purposes until the approval is obtained.
(11) All reports of inspection shall be in writing and certified by the Building Official or the licensed engineer or the architect making the inspection.
(12) Approval of work or construction as a result of such inspection shall not be interpreted to be an approval of a violation of the provisions of this Code or of other law.
(13) The Building Official may require survey of the site and adjoining areas to verify that the structure is located in accordance with the approved plans.
(14) The Building Official or such designated employee shall carry proper identification when inspecting structure or premises in the performance of duties under the provision of this Code.
(15) The Building Official may issue an order for immediate discontinuation of a work and cancellation of a previous permit for such work at any stage if:
* (a) any work is being done contrary to the provision of this Code or other pertinent laws; or
* (b) it is determined by him that the construction is not proceeding according to the approved plan, dangerous or unsafe.
(16) In such cases the Building Official shall notify the owner in writing of such an order by showing the reason for the order, and the conditions under which the cited work will be permitted to resume.
(17) When there is insufficient evidence of compliance with the provisions of this Code, a Building Official shall have the authority to require test as evidence of compliance to be made at no expense to the office of the Building Officials and the test shall be performed by an agency approved by the Building Official.
(18) Any person who shall continue any work after having been served with a stop work order, except such work as that person is directed to perform to remove a violation or unsafe condition, shall be subject to penalties as prescribed by law.
(19) The Building Official may order the current uses of a building discontinued and the building or portion thereof vacated by serving a notice on any person if the Building Official determines that the building or structure or equipment therein regulated by this Code is being used contrary to the provisions of this Code, such person shall discontinue the use within the time prescribed by the Building Official after receipt of such notice to make the structure, or portion thereof, comply with the requirements of this Code.
(20) The Building Official shall maintain records of all applications and drawings received, permits and orders issued, inspections made and reports prepared and submitted by other recognized agencies.
(21) Copies of all relevant papers and documents for enforcement of the Code shall be preserved by the Building Official. All such records shall be kept open to public inspection at all suitable times.
(22) The Building Official may engage, subject to the approval of the Authority, an expert or a panel of experts for opinion on unusual technical issues that may arise in administering the provisions of the Code.
## 22. Board of Appeal
(1) The Authority may, with the approval of the Government, constitute a Board of Appeal to hear and decide appeals of orders, decisions or determinations made by the Building Officials related to the application and interpretation of this Code.
(2) The Board of Appeal shall consist of members appointed by the Authority who are noted for their educations and experience in the relevant field of building construction and whose term of office shall be as decided by the Authority.
(3) The Board of Appeal shall provide reasonable interpretation of the provisions of this Code and determine the suitability of alternative materials or methods of design or construction.
(4) The Board of Appeal shall, with the approval of the Government, adopt rules of procedure for conducting its business, and shall communicate all decisions and findings in writing to the appellant with a copy to the Building Official.
(5) The Board of Appeal shall have no discretion for interpretation of the administrative provisions contained in Part 2 of this Code nor shall be empowered to waive any requirement of this Code.
## 23. Requirement of certification of work
Any planning, design, supervision of construction, repair, maintenance, modification and alteration of buildings, or any other work regulated by the Code shall be certified by a licensed engineer, architect or planner for its compliance with the provisions of the Code as per Tables 2.3.3 and 2.3.4.
## 24. Limits of professional conduct
(1) Any licensed architect, engineer or planner may take assistance from fellow professionals who are not licensed but is member of professional bodies and who shall work under his direct control and he shall be allowed to plan, design and supervise construction, repair, maintenance, alteration and modification of buildings or structures regulated by this Code provided the licensed professional certify compliance of the work with the provisions of the Code.
(2) In case of any violation of the Code the licensed professionals who shall certify will be liable for action through professional bodies and such person may provide any such certificate as long as his or her services are recognized by the Building Official and such recognition is not withdrawn under the provisions of this Code.
## 25. Violation and penalties
Any person, firm, corporation or government department or agency who as owner of the property erects, constructs, enlarges, alters, repairs, moves, improves, removes, converts, demolishes, equips, uses, occupies or maintains any building or structure or cause or permit the same to be done in violation of this Code shall be guilty of an offence and the Authority shall take legal action against such offenders as prescribed by law.
**Explanation.** - For the purpose of this provisions the term “owner” shall include any developer who by appointment, contract or lease is responsible for such activities.
## 26. Professional violation
(1) The engineer, architect or planner responsible for design, supervision or certification of any construction or other work of a building or structure shall ensure compliance of such work with the provisions of this Code.
(2) Any violation of the Code or any other professional misconduct insofar as implementation of the provisions of this Code is concerned including making false statements or issuing false certificates or any incidence of proven professional incapability shall be recommended to the respective professional bodies for necessary disciplinary measure including withdrawal of recognition or registration.
## 27. Obligation of offender
A person shall not be relieved from the duty of carrying out the requirements or obligations imposed on him or her by virtue of the provisions of this Code even if such person is convicted for an offence under the provisions of this Section.
## 28. Conviction no bar to further prosecution
If a person is convicted under the provisions of this Code for failing to comply with any of its requirements or obligations such conviction shall not act as a bar for further prosecution for any subsequent failure on the part of such person to comply.
# Chapter 3: Permits and Inspections
Source: https://docs.sayed.app/bnbc/part-2-development-control/chapter-3-permits-and-inspections
## 3.1 Permits
No building or structure regulated by this Code shall be erected, constructed, enlarged, altered, repaired, moved, improved, removed, converted or demolished without obtaining permit for each such work from the Building official.
Exceptions:
The following works are exempted from the requirement of a permit unless they do not otherwise violate the provisions of this Code, for the said work or any other adjacent property, regarding general building requirements, structural stability and fire safety requirements of this Code:
* (a) Opening or closing of a window or a door or a ventilator;
* (b) Providing internal doors;
* (c) Providing partitions;
* (d) Providing false ceiling;
* (e) Gardening;
* (f) Painting;
* (g) Plastering and patch work;
* (h) Re-flooring;
* (i) Construction of sunshades on one's own land;
* (j) Re-erection of portion of buildings damaged by earthquake or cyclone or other natural calamities, to the extent and specification as existed prior to such damage; and
* (k) Solid boundary walls less than 1.5 m and open boundary wall less than 2.75 m in height.
## 3.2 Types of Permit
Building permit shall comprise of the following 4 (four) stages:
* (a) Land use certificate.
* (b) Large and specialized project permit.
* (c) Building permit.
* (d) Occupancy certificate.
Permit of all or any of the above may be necessary for a particular area/city/town/ municipality. Requirement in this regard shall be incorporated in the building construction byelaws/rules/regulations valid for that particular area/city/town/ municipality.
### 3.2.1 Validity of Permits from the Date of Issuance
The validity of permits for different purposes from the date of issuance shall be as follows:
| (a) | Land use certificate | 24 months |
| --- | ------------------------------------ | ----------------------------------------------------------------- |
| (b) | Large and specialized project permit | 24 months |
| (c) | Building permit | 36 months (unless construction up-to
plinth level is done) |
| (d) | Occupation certificate | Perpetual (unless any change in use
and physical properties) |
### 3.2.2 Permits Obtained Prior to Adoption of Code
If permit for a building or structure or a work regulated by this Code is obtained before adoption of this Code and the building or structure or work for which the permit is obtained is not completed within three years from the date of issuance of such permit, the said permit shall be deemed to have lapsed and fresh permit shall be necessary to proceed further with the work in accordance with the provisions of this Code.
## 3.3 Constitution of Building Permit Committees
### 3.3.1
As per the provisions laid out in the Building Construction Act the government may constitute various committees to examine and scrutinize applications mentioned in Clause 3.2 above and approve or refuse permits thereby.
### 3.3.2
Each committee will have specific Terms of Reference and Work Procedure.
## 3.4 Application For Permit
### 3.4.1
Any person who intends to undertake any work on a building or structure or land regulated by this Code shall file application in writing on the prescribed form furnished by the Building official for that purpose.
### 3.4.2
Application for permit for any work under the provisions of this Code shall be accompanied by necessary documents, drawings, certificates, clearances and other relevant information as required by the Building Official for that particular city/town/municipality/jurisdiction area etc.
### 3.4.3
The drawings shall have any of the sizes specified in the Table 2.3.1:
Table 2.3.1: Drawing Sizes for Permit Applications
| Notation (ISO Standard) | Size (mm) |
| ----------------------- | ---------- |
| A 0 | 841 x 1189 |
| A 1 | 594 x 841 |
| A 2 | 420 x 594 |
| A 3 | 297 x 420 |
| A4 | 210 x 297 |
### 3.4.4 Operation and Maintenance of Utility Services
The government may undertake works for operation, maintenance, development or execution of any of the following utility services without requiring obtaining permit from the Building Official.
* (a) Railways
* (b) National Highways
* (c) National Waterways
* (d) National Gas grid
* (e) National Power grid
* (f) Major Ports
* (g) Airways and Aerodromes
* (h) Telecommunications
* (i) Electronic Broadcasting Services
* (j) Any other services which the Government may, by notification, declare to be a service for the purpose of this Section if the Government is of the opinion that the operation, maintenance, development or execution of such service is essential to the community.
Buildings constructed in connection with these services shall conform to the specifications of this Code.
## 3.5 Disposal of Application
### 3.5.1
Subject to the submission of correct and complete application for the permits included in Sec 3.2 above, should be disposed by the Building Official within the time limit as shown in Table 2.3.2:
Table 2.3.2: Time Limit for Disposal of Application for Permits
| Type of Permit | Maximum time allowed for disposal
(approval or refusal by the Building official) |
| ------------------------------------ | ------------------------------------------------------------------------------------- |
| Land use certificate | 15 days |
| Large and Specialized Project permit | 45 days |
| Building permit | 45 days |
| Occupancy certificate | 15 days |
### 3.5.2
The Building Official shall notify the applicant according to above table as the case may be either approval or refusal of the permit for any work. If the Building Official does not notify the applicant of such approval or refusal within this specified period, the application shall be deemed to have been approved provided the fact is brought to the notice of the Building Official. Such approval shall not be interpreted to authorize any person to do anything in contravention of or against the terms of lease or titles of the land or against any other regulations, bylaws or ordinance operating on the site of the work or any of the provisions of this Code.
### 3.5.3
Refusal of permit shall be accompanied with reason and the Building Official shall quote the relevant sections of this Code which the application/drawings/submissions contravene. The applicant may correct or remove such reasons and reapply for permit with any fee if applicable. The Building Official shall scrutinize the re-submitted application and if there be no further objection it shall be approved and permit issued.
## 3.6 Preparation And Signing of Drawings
### 3.6.1
All drawings submitted for approval shall be prepared and signed by registered professionals as specified in Table 2.3.4, which shall be considered as equivalent to certifying that the drawing on which the signature appears conforms to all the requirements of this Code. Registered Professionals shall put his or her signature with date on the title box of the drawing along with his name, address, professional society membership number, registration number and any other information required by the concerned Building Official.
### 3.6.2
The drawings shall also contain the signature, name and address of the owner.
### 3.6.3
Subject to the classification and use of buildings, all drawings for approval and execution shall be prepared and signed by the registered professionals as per building category specified in Tables 2.3.3 and 2.3.4 corresponding to relevant work.
Table 2.3.3: Building Classification Based on Height, Floor Area and Occupancy Type
| Building Category | Height of Building | Floor Area | Type of Occupancy |
| ----------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------ | ----------------------------------- |
| I | Up to 2 Stories or 8 m height (without
basement) applicable only for areas
beyond the jurisdiction of Development
Authority,
City
Corporation
and
Pourashava | Up to 250 m2 | A (A1-A2) |
| II | Up to 5 Stories (with or without basement) | Up to 1000 m2 | A (A1-A5) |
| III | Up to 10 stories or 33 m height for
engineering design and supervision and
any height for land survey, sub-soil
investigation and architectural design | Up to 7500 m2 | A, B, C, E1, E2,
F1, F2 and H1 |
| IV | Any height | Any Size | All Occupancy
Type |
Table 2.3.4: Eligible Registered/Licensed Professionals for Signing of Design, Drawings, Reports and Documents
| Types of Work | Registered Professional | Cat I | Cat II | Cat III | Cat IV |
| ------------------------------------------------ | ------------------------------------------------------------------------------------------- | ----- | ------ | ------- | --------------------------------------- |
| Land Survey | Civil Engineer | NA | NR | NR | NR |
| Land Survey | Planner | — | NR | NR | NR |
| Land Survey | Diploma Engineer (Civil) | — | 3 | 3 | 3 |
| Land Survey | Certified Surveyor | — | 3 | 3 | 3 |
| Soil Investigation Report | Geotechnical Engineer having experience in soil investigation and soil test report analysis | NA | NR | NR | NR |
| Soil Investigation Report | Civil Engineer having experience in soil investigation and soil test report analysis | NA | 2 | 2 | 5 |
| Architectural Design | Architect | NA | NR | 2 | 8 |
| Architectural Design | Civil Engineer | NA | NR | NE | NE |
| Architectural Design | Diploma Architect | NA | 5 | NE | NE |
| Structural Design | Civil Engineer with experience in structural design or PEng. | NA | 2 | 4 | 8 (having 5 years in structural design) |
| Structural Design | Civil Engineer with M.S in Structural Engineering | NA | 1 | 3 | 8 (having 4 years in structural design) |
| Plumbing Design | Plumbing Engineer | NA | NR | 4 | 8 |
| Plumbing Design | Architect | NA | NR | NE | — |
| Plumbing Design | Diploma Engineer (Civil) | NA | 3 | NE | NE |
| Mechanical (HVAC/Vertical Transportation) Design | Mechanical Engineer | NA | 2 | 4 | 8 |
| Electrical Design | Electrical Engineer | NA | 2 | 4 | 8 |
| Electrical Design | Diploma Engineer (Electrical) | NA | 3 | NE | NE |
| Construction Supervision | Architect/Engineer in their respective field or PEng. | NA | 2 | 4 | 8 |
| Construction Supervision | Diploma Architect/Diploma Engineer in their respective field | NA | 2 | 4 | 20\* |
| Building Demolition | Civil Engineer | NA | NR | 2 | 8 |
| Building Demolition | Diploma Engineer (Civil) | NA | 2 | NE | NE |
| Completion Report | Architect and Engineer with experience in their respective field | NA | 2 | 4 | 8 |
Note: NA: Not Applicable, NE: Not Eligible, NR: Not Required.
\*Shall be countersigned by registered/licensed Architect/Engineer eligible for Building Category IV.
## 3.7 Fees
All applications shall be accompanied by fees as specified by the authority from time to time without which the application shall be deemed to be incomplete.
## 3.8 Responsibilities and Duties of The Owner
### 3.8.1 General
The owner of a building or structure regulated by the provisions of this Code shall be responsible for carrying out the work in conformity with the provisions of this Code. Granting of permission for any work or approval of plans or inspection by the Building Official or any of the deputies shall not relieve the owner from such responsibility.
### 3.8.2 Employment of Technical Personnel
Design, execution and supervision work of any building shall be carried out by authorized Registered Professionals as outlined in Table 2.3.4. Owner shall take the services of as many professionals as required according to type and size of the work.
### 3.8.3 Right of Entry
The owner shall allow the Building Officials to enter the site for the purpose of enforcing the Code as required by the provision of Sec 2.9.6 and for the purpose of inspection as provided in Section 3.10 below.
### 3.8.4 Permits from Other Agencies
The owner shall obtain permit as may be applicable from other concerned agencies relating to building, zoning, grades, sewers, water mains, plumbing, fire safety, signs, blasting, street occupancy, gas, electricity, highways and all other permits required in connection with the proposed work.
### 3.8.5 Information on Progressive Work
The owner shall inform the Building Official about attainment of construction work of different stages as required by the Building Official in prescribed form.
### 3.8.6 Safety Measures
The owner shall take proper safety measures in and around the construction site.
### 3.8.7 Notice of Completion
The owner shall notify the Building Official the completion of the work for which permit was granted in prescribed form. The work shall not be accepted as complete, without a certification from the Building Official.
### 3.8.8 Documents at Site
The owner shall preserve at the site a copy of all permits issued and all drawings approved by the Building Official. Results of tests carried out for determination of conformity of the work with the provisions of this Code shall also be preserved and made available for inspection during execution of the work.
### 3.8.9 Live Load Posted
Where the live loads for which each floor or portion thereof of a commercial or industrial building is or has been designed to exceed 2.4 kN/m2 , such design live loads shall be conspicuously posted by the owner in that part of each storey in which they apply, using durable signs. It shall be unlawful to remove or deface such notices.
## 3.9 Responsibilities and Duties of Technical Personnel
### 3.9.1
To qualify as Architect, Engineer, Construction Supervisor (Architect or Engineer or Diploma Architect or Diploma Engineer) of any building works one shall have membership of the respective professional body in the country. In addition they shall have to qualify as registered professional through an examination (written/oral) to be conducted by their respective professional body as per requirement of this Code.
### 3.9.2
Only technical professionals qualified under Sec 3.9.1 shall design, execute and supervise any building which is subjected to approval granted under this Code.
### 3.9.3
Any lapses on the part of the technical personnel in delivering the requirements of the Code shall call for punitive actions against him/her in the proper forum.
## 3.10 Inspection
All works relating to a building or structure regulated by the provisions of this Code for which permits are required shall be subject to inspection by the Building Official. Modalities and frequency of such inspections shall conform to the requirements put forward by the approving authority.
## 3.11 Unsafe Buildings
### 3.11.1 General
All buildings considered to constitute danger to public safety or property shall be declared unsafe and shall be repaired or demolished as directed by the Building Official.
### 3.11.2 Examination
The Building Official shall examine or cause examination of every building reported to pose threat to safety or be damaged by wear and tear or accident and shall make a written record of such examination.
### 3.11.3 Notification
If a building is found to be unsafe, the Building Official shall notify the owner of the building and specify the defects thereof. The notice shall require the owner within a stated time either to complete the required repair or improvement or demolish and remove the building or portion thereof.
### 3.11.4 Disregard of Notice
In case the owner fails, neglects or refuses to carry out the repair or improvement of an unsafe building or portion thereof as specified in the notice, the Building Official shall cause the danger to be removed either by demolition or repair of the building or portion thereof or otherwise, the cost of which shall be borne by the owner.
### 3.11.5 Cases of Emergency
If the Building Official considers that an unsafe building or structure constitute imminent danger to human life or health or public property, the Building Official shall at once or with a notice as may be possible promptly cause such building or structure or portion thereof to be rendered safe or removed. In such cases the decision of the Building Official shall be final and binding and he or any of his assigned deputies may at once enter such structure or land on which it stands or the abutting land or structure, with such assistance from and at such cost to the owner as may be deemed necessary. The Building Official may also get the adjacent structures vacated and protect the public by an appropriate fence or such other means as may be necessary.
## 3.12 Demolition of Buildings
If a building or structure is to be demolished, the owner shall notify all agencies providing utility services to the building. Such agencies shall remove all their appurtenances and equipment and dismantle all service connections to ensure a safe condition. The Building Official shall not grant any permit for demolition of a building until a release is obtained from the utility services stating that all service connections have been removed in the proper manner. The demolition work shall be done under the supervision of demolition expert as per provisions of Table 2.3.4.
## 3.13 Validity of This Code
### 3.13.1 Partial Invalidity
In case any provision of this Code is held to be illegal or void, this shall have no effect on the validity of any other provision of the Code nor on the same provision in different cases nor on the Code as a whole, and they shall remain effective.
### 3.13.2 Invalidity of Existing Buildings
If any provision of this Code is held to be illegal or void by the Authority as applied to an existing building or structure, validity of that provision or any other provision of the Code in its application to buildings hereafter erected shall not be affected.
## 3.14 Architectural and Environmental Control
### 3.14.1
Besides enforcing the provisions of this Code for normal buildings and structures, the Building Official shall, for special structures such as those listed in Sec 3.14.2 below, also examine the aesthetics and environmental issues vis-a-vis the existing structures and the characteristics of the area, and exercise architectural and environmental control in accordance with the provisions of this Section.
### 3.14.2
Special structures for which architectural and environmental control shall be exerted by the Building Official shall include:
* (a) major public building complexes
* (b) buildings in the vicinity of monuments and major sculptures
* (c) buildings and structures near existing structures identified to be architecturally valuable.
* (d) buildings and structures near historic buildings or in a area of historical or archaeological significance.
* (e) buildings near any structures that represents the special characteristics of an area
* (f) any proposed building or structure that represents the special characteristics or forms part of a larger master plan of an area, and
* (g) any development that may have an effect on the environment or characteristics of an area.
### 3.14.3
The Authority shall, for the purpose of exercising the architectural and environmental control and for identifying existing structures having architectural value, appoint a standing committee comprising noted experts from the fields of Architecture, Archeology, Planning, History, Art, Literature, Engineering or any other discipline which may be deemed relevant. The committee shall examine the aesthetic quality of the proposed building, structure or development and the effect it may have on the characteristics and environment of the area in order to ensure aesthetic continuance of the new structure with the existing ones and aesthetic blending of the new structure with the surroundings. The committee may require additional drawings and information for a detailed study of the proposed work. The committee for the purpose of arriving at their decision, may at their discretion depending on the magnitude of the project and impact it may have on public life, hear the architect of the proposed work who may wish to explain the various features of the project, note comments of other experts in the relevant disciplines, or in exceptional circumstances, institute a public hearing to assess public reaction to the project.
### 3.14.4
The committee may approve the proposed work, recommend changes in the scheme, or disapprove the scheme, for reasons of aesthetics and environmental control.
### 3.14.5
The Building Official shall not issue permit for undertaking the proposed work until obtaining a report from the standing committee stating that the intended work is acceptable in respect of its effect on the environment, landscape, architectural characteristics, historical feature or any other aesthetical quality of the locality, area or landscape concerned.
## 3.15 Making Implementation Procedures
Detailed byelaws and implementation procedure to enforce the provisions of this Code shall be prepared and published by the relevant authorities.
## 3.16 List of Related Appendices
* Appendix A: Form for Application of Land Use/Development/Building Permit
* Appendix B: Form for Certificate of Supervision
* Appendix C: Form for Sanction or Refusal of Land Use/Development/Building Permit
* Appendix D: Form for Appeal against Refusal of any Permit
* Appendix E: Form for Completion Certificate
* Appendix F: Form for Occupancy Certificate
## Appendix A: Form for Land Use/Development/Building Permit
(Position and Address of the Building Official)
First Application to Develop, Erect, Demolish or to Make Alteration in any Part of the Building.
* Type of intended work (check one): Develop / Erect / Demolish / Alter
* Name of the owner
* Contact address, post code, telephone no.
* Name, address and qualification of the engineer, architect, or planner involved, separately for: planning, architectural design, structural design, civil works design, other services design
* Address of the site: plot number, holding number, Dag/Khatian number, Mouza/Block/Sector, street name, municipal ward number
* Documents enclosed (name of document, number of sheets, number of copies): key plan, site plan, subdivision/layout plan, building plan, services plan, specifications, ownership title
* Date and signature of the owner
*For use of the Building Official.* Do not write anything below this line: reference number and date (to be referred to in all subsequent correspondences), received by.
## Appendix B: Form for Certificate of Supervision
* Reference number
* Address of the site: plot number, holding number, street name, municipal ward number
* Type of intended work (check one): Develop / Erect / Demolish / Alter
* Name of the owner, contact address, post code, telephone no.
I hereby certify that the building for which the location, the type of work, and the name and address of owner appear above will be supervised by me as per the provisions of the Bangladesh National Building Code.
* Signature, name, address, and qualification of the engineer, architect, planner, or supervisor; date
## Appendix C: Form for Sanction or Refusal of Land Use/Development/Building Permit
(Position and Address of the Building Official)
* Reference number
In response to your application whose reference number appears above, I hereby inform that the documents submitted along with your application have been (check as appropriate):
* Approved for implementation by the Authority
* Refused by the Authority for violation of the following provisions of the Bangladesh National Building Code (list of the sections violated)
Signature of the Officer, permit number, name of the Officer, official stamp, designation, date.
## Appendix D: Form for Appeal against Refusal of any Permit
* Reference number
The application whose reference number appears above has been refused by the Authority. I hereby appeal against the refusal for the following reasons (list of the justifications for the appeal).
Date and signature of the owner.
*For use of the Building Official. Do not write anything below this line:* received by, date.
## Appendix E: Form for Completion Certificate
* Reference number, permit number
* Address of the site: plot number, holding number, Dag/Khatian number, Mouza/Block/Sector, street name, municipal ward number
* Documents enclosed
* Type of work (check one): Develop / Erect / Demolish / Alter
* Name of the owner, contact address, post code, telephone no.
I hereby certify that the work having the above mentioned detailed particulars has been supervised by me and completed in accordance with the plan and design approved by the permit number cited and the provisions of the Bangladesh National Building Code.
* Signature, name, address, and qualification of the engineer, architect, planner, or supervisor; signature of the owner; date
This Part to be completed by the Building Official.
The work identified by the reference number and permit number at the top of the form is hereby accepted as complete in accordance with the approved plan and design.
* Signature of the Officer, name of the Officer, official stamp, designation, date
## Appendix F: Form for Occupancy Certificate
(Position and Address of the Building Official)
* Reference number, permit number
* Address of the site: plot number, holding number, Dag/Khatian number, Mouza/Block/Sector, street name, municipal ward number
* Documents enclosed
* Type of work (check one): Develop / Erect / Demolish / Alter
* Name of the owner, contact address, post code, telephone no.
I hereby certify that the work having the above mentioned detailed particulars has been completed in accordance with the plan and design approved by the permit number cited and the provisions of the Bangladesh National Building Code. The owner has submitted all the required documents for issuance of occupancy certificate. Thus, I, hereby, certify that the holding may be occupied as \_\_\_ (mention the occupancy type).
* Signature of the Officer, name of the Officer, official stamp, designation, date
# Part II: Development Control Rules
Source: https://docs.sayed.app/bnbc/part-2-development-control/index
Applicability of the Code, the Bangladesh Building Regulatory Authority, and permit and inspection procedures.
Part II establishes who administers and enforces the Code, and the permit and inspection process a building or development must go through.
What this Part covers, and how it applies to construction, alteration, demolition, repair, and land development.
The Bangladesh Building Regulatory Authority, Building Officials, the Board of Appeal, and violations and penalties.
Permit types and validity, application and approval process, professional certification, and unsafe buildings.
# Chapter 1: General Building Requirements
Source: https://docs.sayed.app/bnbc/part-3-general-building-requirements/chapter-1-general-building-requirements
## **1.1 Scope**
This Part of the Code puts forward classification of buildings based on occupancy or nature of use and deals with the general and specific requirements of each of the occupancy groups. Fire resistance requirements are expressed in terms of type of construction which shall conform to the specified fire-resistive properties.
## **1.2 Terminology**
This Section provides an alphabetical list of the terms used in and applicable to this Part of this Code. In case of any conflict or contradiction between a definition given in this Section and that in any other Part of this Code, the meaning provided in this Part shall govern for interpretation of the provisions of this Part.
| Accessibility | The provision in a plot or a building or a facility or any part
thereof that can be approached, entered and used without
assistance by persons with temporary or permanent physical
limitations. |
| ---------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Accessibility
Route | A continuous unobstructed path that starts from the entry and shall
continue through all accessible elements and spaces within a plot
and buildings or facilities thereof up to the exit termination. |
| Accessible | The term accessible or adaptable shall be used as a prefix for
spaces or features which are designed for persons having physical
limitation; such as accessible toilet, accessible kitchen, accessible
lift, and so on. |
| Adaptable | See ACCESSIBLE |
| Area Planning
Authority | A government or semi-government agency or a local body which
has been legally designated to formulate land use or plans of the
area under their jurisdiction. |
| Assembly | In a building or a portion thereof used for gathering of 50 or more
persons for deliberation, worship, reading, entertainment, eating,
drinking, awaiting transportation, or similar uses not limited to
these; or used as a special amusement building, regardless of
occupant load. |
| Atrium | A large volume space within a multistoried building having series
of floor openings or corridors or similar elements in and around
and floors are connected from there and series of openings or a
glazing on roof or a portion thereof constructed with glazing and
having a minimum two stories high. The word Atria or Atriums
are the plural form of Atrium. |
| Balcony | A covered and hanging platform at a height of minimum 2.286 m
from the plinth level of a building and having access from any
floor level and which is laterally open to outer air by three sides
up to 2.06 m in height and edges are protected with guards. Within
an interior space, a balcony is a portion which are positioned
sidewise as similar as Mezzanine. |
| Baluster | Single vertical member of a guardrail or a Handrail or a member
of both which shall be complied with the provisions of this Code. |
| Balustrade | Plural form of BALUSTER. |
| Barrier | A wall or a partition or a floor slab or a ceiling within a building
which confines and protects flow of smoke and fire from the
exposed side of the barrier. The fire rating of barriers shall be
complied with the provisions of this Code. |
| Basement | A floor of a building or a portion thereof which is situated as a
whole or partially at depth of minimum 50 percent of ceiling
height below formation level shall be called as a basement. |
| Building Line | The peripheral lines of a building mass or volume up to which the
plinth area or any floor area may be lawfully extended within a
plot. |
| Carriageway | A path including over bridge or bridge which is open to the outer
air and may or may not be covered or roofed or an underpass,
design and designated for vehicles only. |
| Ceiling Height | Height measured from the top of finished surface of floor level up
to the bottom of roof or ceiling or suspended or false ceiling level
or Beam drops. In case of multistoried building, Vertical distance
in between two slabs from which deduction shall be made for any
suspended or false ceiling or Beam drops. For slope or pitch
ceiling or roof, the minimum value shall be the ceiling height. |
| Common Space
Condition | See NON-SEPARATED SPACE CONDITION |
| Control Area | A space or a room within a building enclosed by barriers with the
fire rated walls, floor and ceiling, where the quantity of hazardous
material shall not be exceeded the maximum allowable quantity
per control area for storing, displaying, handling, dispensing or
using as per provisions of this Code. |
| Detached
Occupancy | A building separated by distance in a same plot to accommodate
different type of occupancies shall be termed as Detached
Occupancy. |
| Development
Authority | A government or semi-government agency or a local body which
has been legally designated to carry out and/or control any works
of land development of an area having jurisdiction. |
| Far (Floor Area
Ratio) | FAR is a ratio between the area of a plot and the sum of floor
areas of building or buildings are erected or intended to be erected
thereof. In the buildings, there may have some specific and
calculated floor areas which shall be treated as bonus or exempted
from the total floor area calculation and such areas shall be
specified by the authorities having jurisdiction. |
| Fire | An uncontrolled fire which poses threat to safety of life or
property or both. |
| Fire Separation
Distance | A minimum distance which to be maintained between potential
sources and/or between structures for fire safety. In case of
differences between building setback and the required minimum
fire separation distance measurement; the higher value shall be
implied. |
| Flood | A Land or a plot normally dry but submerges or drowns as whole
or partially by over flown water from any source. |
| Flood Level | A measurement of height from an existing ground level or from
top level of river water of an area or a locality recorded in a Flood
Hazard Map by the authorities having jurisdiction. |
| Flood Prone
Area | At least once in a year a dry ground of an area or a plot or a
portion thereof flooded at a height of 1m or more shall be
designated as a Flood Prone Area. |
| Floor Height | In a multistoried building, floor height shall be measured from the
top of finished surface of the two successive floor slabs and the
measurement of the top most floor shall be from the top of
finished surface of the floor slab and the top of the finished roof,
in case of the slope roof, measurement shall be taken up to pick of
that slope. |
| Frontage | Irrespective of the entry provision to a plot, full or partial length of
any sides of a plot which are abutted to roads or streets shall be
designated as frontage. |
| Formation Level | Finished ground level of a plot. For hilly areas formation levels
shall be the gradient of the plot surface. |
| Gallery | A special type of seating arrangement where each and every row
or tier of seats are successively elevated to provide a clear view to
audiences or spectators within and around a playground or outdoor
or indoor stadium or within an auditorium or in a hall. |
| Guard | A vertical protective barrier erected up to a height along exposed
edges of stairways, balconies and similar areas. |
| Head Room
Clearance | A vertical distance measured from the top of finished floor level
up to the bottom of ceiling or lowest roof level or bottom of beam
drop or bottom of any hanging element within a space. In case of a
stairway, a vertical distance measured from the bottom surface of
flight or ceiling or beam drop to any outer edge point of a tread
below and for the landings ceiling height measurement system
shall be adopted to determine head room clearance. |
| Helistop | A designated area on ground or on water or on a portion of a
building for helicopter landing or takeoff without servicing,
repairing and refueling facilities. |
| High Rise
Building | Any building which is more than 10-storey or 33 m high from
reference datum. Building appurtenances like overhead water
tank, machine room, communication tower etc. will not be
considered in determining the height. |
| Lighting Shaft | A space within a building which is fully enclosed by all sides and
shall be open to the sky to provide daylight to adjacent interiors
and less than the dimensions that stipulated for minimum closed
or internal courts of corresponding to the building heights. |
| Loft | An intermediate space in-between a floor or a ceiling and under a
pitch or a slope roof of a building. |
| Mandatory Open
Space | The spaces within a plot which shall remain unpaved with or
without vegetation to allow water penetration and uncovered up to
the sky from formation level of the building. No underground or
above ground construction is allowed in such spaces. |
| Mezzanine Floor | Within one space where more than one floor exists, the floor at the
lowest level shall be designated as main floor and each
Intermediate floor is limited to an area which is not more than one
third of the main floor under one roof or one ceiling, thus gives
two or more useable floor levels. These types of intermediate
floors shall be designated as mezzanine floors. Mezzanine floor
may be as gallery or flat floor type and which also includes
interior balcony. |
| Mixed
Occupancy | When two or more occupancies are amalgamated in a building
shall be termed as Mixed Occupancy. |
| Non Separated
Space Condition | Walls or partitions between compartments, rooms, spaces or areas
within a building or part of a building which are not separated by
an approved fire rated barrier walls or partitions shall be
designated as non-separated space condition or effective
undivided single space. |
| Openings | Apertures or holes in any wall of a building that allow air to flow
through and which are designed as open. |
| Opening,
Vertical | An opening through a floor or roof of a building. |
| Open Space | Open space within a plot includes all spaces other than spaces
covered by the Maximum Ground Coverage (MGC). |
| Plinth | Bases of the building and the elements that negotiate with the
ground. |
| Plinth Level | Height of a covered finished floor which is just above the
formation level and measured from the formation level up to the
top of that finished floor. |
| Plinth Area | The elements from the building bases which are exposed above
the formation level to form a covered floor area by joining the
peripheral points of the elements which are intersected finished
floor plane at the height of plinth level shall be designated as
Plinth Area. |
| Plot | A scheduled piece or parcel of land which is classified and
restricted to its intended use. |
| Ramp | A sloping walkway which is steeper than 1 in 20 but not steeper
than 1 in 8 and shall have guard and handrail. |
| Ramp,
Accessibility | A sloping walkway not steeper than 1 in 12. |
| Ramped
Driveway | Ramped Driveways are inclined floors that provide access to
vehicles between two levels. Ramped walkway when provided
side by side of a ramped driveway shall be separated by safety
guard rails and curbs. A sloping driveway or Ramped Driveway
steeper than 1 in 8 shall not be credited as a component of means
of exit. |
| Ramp Gradient | Ramp gradient refers to the ratio of the inclination of a ramp
(height by length ratio) measured along the center line of the
ramp. |
| Road Level | The road level means top surface at the center point of the road
width which is used for site entry and shall be considered as the
reference point for measuring height or depth of any development. |
| Roof | Weather exposed and uncovered surface of the topmost or the
terminal ceiling of a building which may be horizontal or pitched
or may have slopes shall be treated as the roof of a building. |
| Separated
Occupancy | A building or a portion thereof separated by barriers with wall or
ceiling slab that into two or more parts to accommodate different
type of occupancies in different parts. |
| Separate Space
Condition | Rooms, spaces or areas within a building when separated by
approved barrier wall. |
| Separation Wall | This is a peripheral wall of a building or a building which shall be
divided into two or more or a common wall between two buildings
to control spreading of fire as per provisions of this Code. |
| Site | See PLOT |
| Smoke Draft
Barrier | A vertical panel dropped from the ceiling of a building or portion
thereof to protect and control the movement of smoke draft during
fire. The construction of such smoke draft barriers shall be
complied with the provisions of this Code. |
| Stage | An elevated platform which is designed or used for presentation of
plays or lectures or other entertainments in front an assembly of
spectators or audiences. |
| Stage, Interior | An elevated platform within a building which is designed or used
for presentation of plays or lectures or other entertainment in front
an assembly of spectators or audiences. |
| Stage, Legitimate | Ceiling Height of a stage from the top surface of the platform is
15.24 m or more shall be designated as a legitimate stage. |
| Storage Density | A storage or display of solid or liquid merchandises shall not be
exceeded 976 kg/m2or 814 L/m2respectively and shall be limited
to the exempted quantity of an actually occupied net floor area.
Maximum height of display or storing of merchandises shall not
be exceeded 1829 mm or 2438 mm respectively. Allowable
Height and Quantity may be less depending on the total area and
the ceiling height of a store or a display. |
| Street Or Road | An open to outer air and unobstructed space having required width
and used by the public as pedestrian or walkway, or animal or
vehicular movement or any combination of these for the purpose
of access to a plot or plots and is connected with the national
public transportation system other than railway track shall be
designated as street or road which may or may not be paved. |
| Street Or Road
Width | The width of any street or road shall be measured form any plot to
its opposite or face to face plot distance. For the determination of
a road width, measurements shall be taken up to the connection of
the national public transportation system other than railway track
from any plot and the least width shall be the road width. |
| Street Floor
Level | A story or floor level of a building which is accessible at the main
entrance of a building from the street or from the outside at
ground level and the floor shall not be more than three risers
above or below the grade level. |
| Structural Frame | All members or elements such as columns, girders, beams, trusses
and spandrels which forms a frame and have direct connections
with bearing and transferring as an integral and essential elements
for the stability of a building or a structure as a whole. |
| Surge Prone Area | Expected occurrence of a surge or wave of water may flow above
1 m or higher from the formation level. |
| Tall Structure | A building used for human occupancy located more than 80m
high from the center of the adjacent road level or from lowest
level of the fire department vehicle access. |
| Terrace | A paved surface not steeper than 1 in 20 and adjacent to a building
which is connected by a stairway or a walking ramp or at the same
level of any floor below the roof level of a building and at least
one side of that area is exposed to the weather and having the
guards and open to the sky. |
| Universal
Accessibility | See ACCESSIBILITY |
| Unprotected | The element that shall have no prerequisites of fire protection
rating. |
| Ventilation
Shaft, Natural | A space sidewise enclosed but open to sky used to provide
ventilation as inlet and/or outlet to adjacent interiors of
dimensions less than that stipulated for internal courts of
corresponding to building heights. |
| Verandah | Portions of a building at any level which have ceiling or roof and
at least one side open up to 2.13 m height to the outside air and
have guards as per provisions of this Code. |
| Walkup Building | A multi storied building which does not have any mechanical
means of vertical circulation other than stairway shall be
designated as a walkup building and the maximum height of the
walkup building shall be as per provision of this Code or as
approved by the authority having jurisdiction. |
## **1.3 Land Use Classification**
A city or a township or a municipality or a union or any other habitat development shall be brought under a structured planning including detailed area planning to implement the intended land use pattern, transportation and maintaining environmental conditions by the development or planning authorities and shall be approved by the government. This land use classification may divide an area into zones such as residential, commercial, industrial, storage, green park, agricultural land, reserved area etc. or any combination of these. The land use zones shall be shown on the approved master plan of the area and the planning regulation shall clearly state the permitted occupancies, restricted occupancies and conditionally permitted occupancies for each zone.
## **1.4 Occupancy and Construction Classification of Buildings**
Every building or portion there of shall be classified according to its use or character of occupancy. A brief description of such occupancy groups is presented in Table 3.1.1. Details of all occupancy group and sub-divisions are set forth in Sec 2.1 of Chapter 2 of this Part. Types of construction based on fire resistance are specified in Table 3.1.2. Details of such types of construction are set forth in Chapter 3 of this Part. Any development permit for a site or a location shall clearly mention the permitted occupancy and construction type in accordance to Tables 3.1.1 and 3.1.2 for the existing or proposed building.
**Table 3.1.1: Summary of Occupancy Classification**
| **Occupancy**
**Type** | \*\*Subdivision \*\* | **Nature of Use or Occupancy** | **Fire**
**Index**\* |
| ------------------------------ | -------------------- | ----------------------------------------------------------------- | ------------------------- |
| A: Residential | A1 | Single family dwelling | 1 |
| | A2 | Two families dwelling | 1 |
| | A3 | Flats or apartments | 1 |
| | A4 | Mess, boarding houses, dormitories and
hostels | 1 |
| | A5 | Hotels and lodging houses | 1 |
| B: Educational
Facilities | B1 | Educational facilities up to higher secondary
levels | 1 |
| | B2 | Facilities for training and above higher
secondary education | 1 |
| | B3 | Pre-school facilities | 1 |
| C: Institution for | C1 | Institution for care of children | 1 |
| Care | C2 | Custodial institution for physically capable
adults | 1 |
| | C3 | Custodial institution for the incapable adults | 1 |
| | C4 | Penal and mental institutions for children | 1 |
| | C5 | Penal and mental institutions for adults | 1 |
| D: Healthcare | D1 | Normal medical facilities | 2 |
| Facilities | D2 | Emergency medical facilities | 2 |
| E: Business | E1 | Offices | 2 |
| | E2 | Research and testing laboratories | 2 |
| | E3 | Essential services | 2 |
| F: Mercantile | F1 | Small shops and market | 2 |
| | F2 | Large shops and market | 2 |
| | F3 | Refueling station | 2 |
| G: Industrial | G1 | Low hazard industries | 3 |
| Buildings | G2 | Moderate hazard industries | 3 |
| H: Storage | H1 | Low fire risk storage | 3 |
| Buildings | H2 | Moderate fire risk storage | 3 |
| I: Assembly | I1 | Large assembly with fixed seats | 1 |
| | I2 | Small assembly with fixed seats | 1 |
| | I3 | Large assembly without fixed seats | 1 |
| | I4 | Small assembly without fixed seats | 1 |
| | I5 | Sports facilities | 1 |
| J: Hazardous | J1 | Explosion hazard building | 4 |
| Building | J2 | Chemical hazard building | 4 |
| | J3 | Biological hazard building | 4 |
| | J4 | Radiation hazard building | 4 |
| K: Garage | K1 | Parking garage | 2 |
| | K2 | Private garage | 1 |
| | K3 | Repair garage | 3 |
| L: Utility | L | Utility | 2 |
| M: Miscellaneous |
M1 | Special structures | 2 |
| | M2 | Fences, tanks and towers | 1 |
* Fire Index: fire index is an absolute number, Occupancy group having same fire index may be permitted as mixed occupancy and different fire index shall be separated or detached as per provisions of this Code.
**Table 3.1.2: Summary of Classification of Buildings Based on Types of Construction**
| **Construction Group** | **Construction Type** |
**Description** |
| --------------------------- | --------------------- | ---------------------- |
| | Type I-A | 4 hour protected |
| | Type I-B | 3 hour protected |
| Group I: Non-combustible | Type I-C | 2 hour protected |
| | Type I-D | 1 hour protected |
| | Type I-E | Unprotected |
| | Type II-A | Heavy timber |
| | Type II-B | Protected wood joist |
| Group II: Combustible | Type II-C | Unprotected wood joist |
| | Type II-D | Protected wood frame |
| | Type II-E | Unprotected wood frame |
## 1.5 Requirements of Plots
### **1.5.1 General Requirements**
#### 1.5.1.1
No building shall be constructed on any site which is water logged, or on any part of which is deposited refuse, excreta or other objectionable material, until such site has been effectively drained and cleared to the satisfaction of the Authority.
#### 1.5.1.2
Provision shall be kept for any space within the plot left vacant after the erection of the building to be effectively drained by means of surface or underground drainage system.
#### 1.5.1.3
Basic minimum sanitary waste and excreta disposal facility shall be created on the premises, whether or not the plot is served by a disposal system provided by any utility service authority or agency.
#### 1.5.1.4
Written approval of the Authority or the appropriate drainage and sanitation authority shall be obtained for connecting any soil or surface water drain to the sewer line.
### **1.5.2 Clearance from Overhead Electric Lines**
A building or any part thereof shall not be erected within, nor any auxiliary part of the building be allowed to come closer to the distance shown in Table 3.1.3 from any overhead electric line.
**Table 3.1.3: Minimum Distances from Overhead Electric Lines**
| **Line Voltage** | **Vertically (m)** | **Horizontally (m)** |
| --------------------------------------------- | -------------------------------------- | -------------------------------------- |
| Low to medium voltage lines and Service lines | 2.5 | 1.25 |
| High voltage lines up to
33 kV | 3.5 | 1.75 |
| High voltage lines | 3.5 plus 0.3 for each | 1.75 plus 0.3 for each |
| beyond 33 kV | additional 33 kV or part
thereof. | additional 33 kV or part
thereof. |
### **1.5.3 Road Level, Formation Level and Plinth Levels**
#### 1.5.3.1
Road level shall be lower than the habitable formation level of an area, except that of a hilly region. When a road is designed and designated as a part of national disaster management system, formation levels shall be determined by the authorities having jurisdiction.
#### 1.5.3.2
The formation level of a plot shall not be lower than the adjacent road levels, except that of a hilly region. For hilly region, the elevation of the formation level shall be determined by the authority having jurisdiction. Where areas are not susceptible to flood or water logging, the formation level shall not be more than 450 mm high from the surface level of the center line of the adjacent roads.
#### 1.5.3.3
The plinth level of a building shall be at least 450 mm above the surface level of the center line of the adjacent road. In Flood or Surge prone area plinth level shall be determined by the development authority having jurisdiction.
### **1.5.4 Boundary Wall**
#### 1.5.4.1
Solid boundary walls of a plot or in between plots shall not be higher than 1.5 m or a boundary made of grill, screen, balustrade etc. with a maximum height of 2.75 m shall not require the permission of the Authority. For boundary walls made of a combination of solid wall and grill or screen, the solid wall portion shall not be higher than 1.5 m. The Authority may, on specific application, permit the use of higher boundary walls.
#### 1.5.4.2
Construction of a boundary wall shall be capable to resist collapsing as per provision of this Code.
## **1.6 Plot Sizes**
Plot divisions and plot sizes are part of integrated planning decision of detail area plan and shall be determined by the Area Development Authority having jurisdiction. Where no such guideline exists or yet to be undertaken, the criteria mentioned in Sec A.5 of Appendix A regarding plot size shall be applicable.
## **1.7 Means of Access**
The provision of means of access is implied on an area or a plot when more than one plots are intended to be created or when more than one buildings are intended to be erected respectively, where such plots or buildings do not have frontage to or not approachable by a public or a private road or street. All buildings within such area or a plot shall have access facilities which shall be connected with national road transportation system. The components of means of access shall comply with the followings:
* (a) The access facilities shall meet the requirements of fire service vehicles and engines movement for rescue and fire extinguishment operation.
* (b) Where required for fire apparatus access roads shall have an unobstructed carriageway width of 4.8 m and the minimum vertical clearance shall be 5m. The width and vertical clearance of fire apparatus access roads may be increased as per requirement of the fire authority, if the clearances are not adequate to provide fire apparatus access.
* (c) Access roads longer than 30 m having a dead end shall be provided with appropriate provisions for turning around of the fire apparatus at the dead end.
* (d) The provision of fire apparatus stall be marked by approved sign.
* (e) For large Assembly Occupancy of I1, I3 and I5, width of the approach road shall not be less than 15 m.
* (f) The minimum width of the approach road for all plots other than residential and assembly occupancies mentioned in Sec 1.7(e) and Sec 1.7(g) shall be 10.8 m.
* (g) For area fully covered by private hydrant system with street side hydrant points and/or hydrants within the building equivalent to fire service and civil defense department’s specification and the buildings have fire stairs as per provisions of this Code, the requirements of Sections 1.7(a), (b) and (c) may be exempted. This provision shall not be applicable for planning new developments. The minimum width of access roads for plot divisions in new developments shall follow guidelines of Table 3.F.1 of Appendix F.
### **1.7.1 Internal Access Road**
Internal access road is legally restricted for thoroughfare to the citizens and/or reserved for a group of people of a plot or an area that shall have access provisions for the department of fire service and civil defense.
#### 1.7.1.1
The width of access roads and drive ways in a plot or an area shall be decided by the number and height of the buildings served thereby.
**Table 3.1.4: Maximum Permissible Length of Internal Access Roads in NonResidential Plots**
| **Width (m)** | **Maximum Permissible Length (m)** |
| ------------- | ---------------------------------- |
| 6 | 80 |
| 7 | 150 |
| 8 | 300 |
| 10.8 or more | Unlimited |
### **1.7.2 Pedestrian Path or Walkway or Footpath**
Any path including over bridge or bridge which is open to the outer air and may or may not be covered or roofed or an underpass design and designated for walkers only shall be designated as pedestrian path or walkway or footpath.
#### 1.7.2.1
An uncovered paved pedestrian path that links buildings and the approach road shall not be included as a floor area of a building.
#### 1.7.2.2
The walkways shall not be used for any other purpose than pedestrian movement and as accessibility route.
#### 1.7.2.3
The minimum width of the pedestrian path shall not be less than the calculated width of connected corridor or passage or walking ramp of a building for entry or exit provided it is not enclosed by adjacent walls on both sides; for pedestrian paths enclosed by adjacent walls on both sides the minimum width shall be 1.25 m. For public buildings and places where high pedestrian movement is expected, Table 3.F.1 of Appendix F may be followed.
#### 1.7.2.4
Pedestrian walkways as accessibility route in public buildings shall comply with the provisions of this Code. Any changes in elevation in accessibility route shall comply with the provisions of Appendix D (Universal Accessibility).
## **1.8 Open Spaces Within a Plot**
### 1.8.1
Minimum open space requirements for the sides, rear and frontages of a plot shall be as per the provisions of this Code or the authority having jurisdiction. In absence of such guideline, provisions of Sec 1.8.2 to Sec 1.8.11 shall decide the provisions of open space for any building or buildings within a site. All such open spaces shall ensure access of the users.
### 1.8.2
At least 50 percent of the minimum open space in a plot shall remain unpaved with or without vegetation to allow water penetration.
### 1.8.3
The total open area in a plot on which a building of educational, institutional, health care occupancy is constructed shall not be less than 50 percent of the plot area.
### 1.8.4
The total open area in a plot on which a building of any occupancy, except those mentioned in Sec 1.8.3, is constructed shall not be less than 33 percent of the plot area.
### 1.8.5
For the purpose of Sec 1.8.2, Sec 1.8.3 and Sec 1.8.4, the total open area shall include all exterior open spaces and interior courtyards, but exclude the area of any lighting and ventilation shaft.
### 1.8.6
For approved row type or cluster type housing or site and service schemes, the requirement of Sec 1.8.3 shall be applicable.
### **1.8.7 Separation of Buildings in the Same Plot**
#### 1.8.7.1
More than one building in a plot shall comply with the requirements of means of access and setback distances in relation with the corresponding building height and the occupancy classification as per provisions of this Code and laws of the land.
#### 1.8.7.2
To determine the separation distance between buildings of same height and same occupancy an equidistant imaginary line shall be drawn between the buildings where each building shall comply with requirement of setback and fire separation distance from that imaginary line.
#### 1.8.7.3
Exception: Utilities under Occupancy L is incidental to operation in all type of occupancy except Occupancy J and shall not require the separation distance from the main occupancy. This exception shall not be applicable for Occupancy J.
#### 1.8.7.4
When variation in either height or occupancy occurs, the imaginary line shall satisfy the setback distances for each individual building separately as shown in Figure 3.1.1.
#### 1.8.7.5
Due to the common walls, row or semi-detached houses shall be treated as one building. For semi-detached houses separation distance in the detached sides shall comply with Sec 1.8.7.2 and Sec 1.8.7.3.
![Separation distance for variation in occupancies and heights]()
### **1.8.8 Front Open Space for All Buildings**
#### 1.8.8.1
Irrespective of the height of building frontage open space, as defined in Figure 3.1.2, shall be constructed at a distance of at least 4.5 m from the center of the street or at least 1.5 m from the street-front property line whichever is larger.
#### 1.8.8.2
In a corner situation where two frontages of a plot intersects each other and form a sharp corner a turning clearance with a minimum radius of 2 m shall be required as per guidelines of Figure 3.1.3. No construction or visual obstruction shall be allowed within such turning clearance space.
### **1.8.9 Side and Rear Separation Distances**
#### 1.8.9.1
The minimum side and rear open space, as defined as Figure 3.1.2, requirements of a plot for buildings of various occupancy classes shall be as specified in Table 3.1.5.
#### 1.8.9.2
For approved row type residential, mercantile or office as may be permitted by the respective city or development authority and for approved affordable row type, cluster or site and service schemes, the requirement of side separation distance may be waived as per provisions of this Code.
![Definition of front, side and rear of a plot]()
![Restrictions for corner-plots]()
#### 1.8.9.3
For semi-detached buildings approved by the city or development authority, which are permitted to be constructed with one side on the property line or with pounding gap, the minimum requirements of open space, specified in Sections 1.8.9.1 and 1.8.9.2, for the side opposite to that property line shall be increased as per Table 3.1.5. The requirement of separation distance for the remaining sides shall remain unchanged.
**Table 3.1.5: Minimum Rear and Side Open Space Requirements of a Plot**
| **Occupancy** | **Plot Size**\*
**(m²)** | **Rear Separation**
**Distance (m)** | **Side Separation**
**Distance****a****(m)** |
| ------------------------------------------------------------------------------------------------------ | ------------------------------------------ | ------------------------------------------ | ------------------------------------------------------------ |
| Residential (Row type,
not higher than 15m or 4
stories) | Not over 67
Over 67 to below
134 | 1.25
1.5 | Nilb
Nilb |
| Residential (Semi- | 134 to 268 | 2.5 | PGc, 2.5 |
| detached, not higher than
10 stories or 33 m) | Over 268 | 3.0 | PGc, 2.5 |
| Residential (Detached,
Not higher than 10 stories
or 33 m) | 134 to 268 | 2.5 | 1.25 |
| Residential (Detached,
Not higher than 10 stories
or 33 m) | Over 268 | 3.0 | 1.25 |
| Residential(Detached,
Higher than 10 stories or
33 m) | Over 268 | 3.0 | 3.0 |
| Institution for care | As permitted for this
occupancy | 3.0 | 3.0 |
| Educational | As permitted for this
occupancy | 3.0 | 3.0 |
| Assembly | Any | 3.0 | 3.0 |
| Business and Mercantiled
(Not higher than 10
stories or 33 m) semi-
detached | Any | 1.5 | PGc, 3.0 |
| Business and Mercantile
(Not higher than 10
stories or 33 m) Detached | Any | 1.5 | 1.25, 2.5 |
| Business and Mercantiled
(Higher than 10 stories or
33 m) semi-detached | Over 536 | 3.0 | PGc, 6.0 |
| Business and Mercantile
(Higher than 10 stories or
33 m) Detached | Over 536 | 3.0 | 3.0 |
| Industrial | As permitted for this
occupancy | As per provisions of
this Code |
As per
provisions of
this Code |
| Storage | As permitted for this
occupancy | As per provisions of
this Code |
As per
provisions of
this Code |
| Hazardous | As permitted for this
occupancy | As per provisions of
this Code |
As per
provisions of
this Code |
| Notes: | | | |
* a The two dimensions separated by comma stands for each of side separation distances of a semi-detached development.
* b No side separation distance is required between buildings up to 15 m or 4 stories even for independent plots.
* c PG stands for ‘Pounding Gap’, which is a calculated gap for safe distance to avoid pounding due to lateral loads as per provisions of Part 6 of this Code. This gap is not required if the adjoining plots are consolidated and built monolithically. Where pounding gap do not comply with the minimum separation distance, all walls within the separation distance shall be barrier walls.
* d Mercantile occupancies shared walls between adjacent plots shall only be allowed in accordance to the detail area plan (DAP) administered by the development authority.
* For narrow plots (with site frontage below 12 m) of size 268 m² or above in unplanned areas, the local regulatory authority may allow semi-detached typology with a minimum side separation distance of 3m on the unattached side.
### **1.8.10 Courtyard and Interior Courtyard**
An area having proper dimensions as per provision of this Code and open to the sky from the formation level and surrounded by a building or a group of buildings or walls or combination thereof shall be designated as Courtyard. The minimum size of such courtyard shall be derived from Table 3.1.6 depending on the height of the highest building or highest wall abutting the courtyard. The shorter side dimension of such courtyard shall not be less than one-third of the longer side dimension. All such courtyards shall remain open to sky over its entire cross section.
When the sum of exposure area of a courtyard to outer air through its adjacent walls exceed more than thirty percent area of its total peripheral enclosure, it shall be designated as Open courtyard. All other courtyards shall be designated as Interior or Closed courtyard.
#### 1.8.10.1
If any room depends entirely on an interior open space for its natural light and ventilation, such interior open space shall be in the form of an interior courtyard open to the sky over its entire cross-section. The interior courtyard shall have the minimum dimensions depending on the height of the building as specified in Table 3.1.6. The shorter side dimension of such interior courtyard shall not be less than one-third of the longer side dimension.
**Table 3.1.6: Minimum Area of Interior Courtyard**
| **No. of Stories** | **Maximum Height (m)** | **Minimum Net Area of the**
**Interior Courtyard, m****2** |
| ------------------ | ---------------------- | -------------------------------------------------------------------------- |
| Up to 3 | 11 | 9 |
| 4 | 14 | 16 |
| 5 | 17 | 25 |
| 6 | 20 | 36 |
| 7 | 23 | 49 |
| 8 | 26 | 64 |
| 9 | 29 | 81 |
| 10 | 32 | 100 |
| 11 | 36 | 121 |
| 12-13 | 42 | 144 |
| 14-15 | 48 | 196 |
| 16-17 | 54 | 256 |
| 18-20 | 63 | 361 |
| Notes: | | |
1. For buildings above 20 storeys height, the size of the interior courtyard shall not be less than the square of one-third the height of the tallest wall abutting the courtyard.
2. Enclosed open to sky spaces used to provide ventilation as inlet/outlet or daylight to adjacent interiors having dimensions less than that stipulated for internal courts of corresponding storey height given in this Table will be considered ventilation or lighting shafts and not interior courtyards and will follow minimum requirements stipulated in Table 3.1.11
#### 1.8.10.2
The courtyard shall not be interrupted by any form of construction at the courtyard level, except landscaping, sculpture, walkways and water bodies.
#### 1.8.10.3
If the courtyard is to serve as a component of the means of egress, it shall be accessible from all exit points at ground level.
### **1.8.11 Permitted Construction in the Mandatory Open Space**
#### 1.8.11.1
Landscaping, sculpture, walkways, water body shall be permitted in the open space. Any such construction shall comply with Sec 1.8.2 of this Chapter.
#### 1.8.11.2
A maximum of 50 percent of the open space in a plot required by the provisions of Sec 1.8.8 and Sec 1.8.9 may be used for construction of garage, ramps, caretaker or guards quarter and other services auxiliary to and required for the main occupancy of the building, provided that the requirement of community open space in Occupancy A3 is attained, and building is not higher than 10 storey or 33 m, and provided further that conditions (a) to (g) below are satisfied:
* (a) No such construction permitted in the open space shall be higher than 2.75 m from the formation level of the plot, except for the tops of inverted beams or intermittent parapets, which may rise up to 3.25 m.
* (b) No window, door or ventilator shall be placed on any wall adjacent to the abutting plot or street.
* (c) Entrance to the garage or sloping drive way shall not be directly from a public road or street. Distance between the plot line adjoining the road and the entrance to a garage or a sloping drive way shall be kept at least 1.5 m or 4.8 m respectively.
* (d) Drainage from the roof or any other part of such construction shall not be allowed to discharge into the adjacent property. Drainage from any part shall not discharge directly into the street through spouts.
* (e) No structure or room shall be constructed over the garage or any other permitted service structure within the limits of the mandatory open space.
* (f) The roof of any such construction permitted in the mandatory open space shall not be used as a balcony or a terrace or in any such manner that would interfere with the privacy of the occupants of the adjacent property.
* (g) No toilet, generator room or electrical substation shall be constructed adjoining the abutting property or street.
#### 1.8.11.3
Edges of slope roof or cornice of the building may be projected into the mandatory open space for a maximum distance of 750 mm. Such extensions shall not be accessible from the building at any level. The construction of a roof or a cornice shall be as such that rain or other water shall not fall from there into the adjacent plot or street.
#### 1.8.11.4
Sunshades over exterior doors or windows of the building may extend into the mandatory open space for a maximum distance of 750 mm, provided that such sunshades are at least 2.5 m above the formation level of the ground.
#### 1.8.11.5
Cantilever canopy at a clear height of at least 2.5 m above the formation level may project into the mandatory open space provided that a horizontal clearance of at least 1.5 m is maintained between the edge of the canopy and the property line. The top surface of such canopy shall not be used as a balcony and shall not be accessible from the building.
#### 1.8.11.6
Balconies at levels higher than 6 m may project into the mandatory open space by not more than 0.9 m provided that a clearance complying the separation distances required in Sec. 1.8.8 and Sec. 1.8.9 are maintained between the edge of the balcony and the property line. Balcony shall be constructed as per provisions of this Code.
#### 1.8.11.7
Water reservoirs, septic tanks, inspection pits, sewer and other underground or above ground service lines shall be permitted in the open space provided that no part of such construction is elevated more than 150 mm above the formation level and the 50 percent mandatory open space shall be unpaved green area.
## **1.9 General Height and Area Limitations**
### 1.9.1
Authorities having jurisdiction shall permit the built area and building height for an area in accordance to the proposed density of the detail area plan (DAP). Where no such guideline is available, the height of the building shall be determined by the guidelines of Sections 1.9.2.1 to 1.9.2.9 and the built area will be a resultant of open space requirement and permitted height.
### **1.9.2 Height Limitations Based on Road Width**
#### 1.9.2.1
The maximum height of any building of Type I-A and Type I-B construction shall not exceed the nominal value of two times the sum of the width of the front road and the front open space (distance between the front property line and the building).For the purpose of fulfilling this requirement, the height limitations specified in Table 3.1.7 shall apply.
#### 1.9.2.2
For plots having front road width not less than 23 m in an approved residential or business and/or mercantile area, there shall be no restriction on height for residential, business and mercantile buildings of Type I-A and I-B construction provided the minimum open space requirements specified in Table 3.1.8 are satisfied.
#### 1.9.2.3
For Type I-C construction, the maximum permissible height of the building shall be 4 storeys or 14 m for values of two times the sum of the width of the front road and the front open space not less than 13.6 m.
**Table 3.1.7: Height Limitations Based on Road Width and Front Open Space**
| **2 × (Front Road Width Plus Front Open Space)** | **Group I: Type I-A and I-B** No. of storeys | **Group I: Type I-A and I-B** Height (m) | **Group I: Type I-C** No. of storeys | **Group I: Type I-C** Height (m) | **Group I: Type I-D** No. of storeys | **Group I: Type I-D** Height (m) | **Group II: Type II-A, II-B, II-D** No. of storeys | **Group II: Type II-A, II-B, II-D** Height (m) |
| ------------------------------------------------ | -------------------------------------------- | ---------------------------------------- | ------------------------------------ | -------------------------------- | ------------------------------------ | -------------------------------- | -------------------------------------------------- | ---------------------------------------------- |
| Below 10.6 m | 3 | 11 | 2 | 8 | 2 | 8 | 2 | 8 |
| 10.6 m to below 13.6 m | 4 | 14 | 3 | 11 | 2 | 8 | 2 | 8 |
| 13.6 m to below 16.6 m | 5 | 17 | 4 | 14 | 3 | 11 | 3 | 11 |
| 16.6 m to below 19.6 m | 6 | 20 | 4 | 14 | 3 | 11 | 3 | 11 |
| 19.6 m to below 22.6 m | 7 | 23 | 4 | 14 | 3 | 11 | 3 | 11 |
| 22.6 m to below 25.6 m | 8 | 26 | 4 | 14 | 3 | 11 | 3 | 11 |
| 25.6 m to below 28.6 m | 9 | 29 | 4 | 14 | 3 | 11 | 3 | 11 |
| 28.6 m to below 31.6 m | 10 | 32 | 4 | 14 | 3 | 11 | 3 | 11 |
| 31.6 m to below 34.6 m | 11 | 36 | 4 | 14 | 3 | 11 | 3 | 11 |
| 34.6 m to below 37.6 m | 12 | 39 | 4 | 14 | 3 | 11 | 3 | 11 |
| 37.6 m to below 40.6 m | 13 | 42 | 4 | 14 | 3 | 11 | 3 | 11 |
| 40.6 m to below 43.6 m | 14 | 45 | 4 | 14 | 3 | 11 | 3 | 11 |
| 43.6 m to below 46.6 m | 15 | 48 | 4 | 14 | 3 | 11 | 3 | 11 |
*...and so on in increments of 3 m.*
Notes:
1. For plots with front road width (Sec 1.9.2.5) not less than 23 m, residential and business and mercantile buildings of Type I-A and I-B construction shall have no height restriction subject to additional open space requirements (Sec 1.9.2.2).
2. The maximum permissible height for Type I-C construction is 4 storeys or 14 m (Sec 1.9.2.3).
3. The maximum permissible height for Type I-D and I-E of Group I construction and all types of Group II construction is 3 storeys or 11 m (Sec 1.9.2.4).
* For all Unprotected Construction Types I-E of Group I, Type II-C and Type II-E of Group II the maximum allowable storey and height shall be one storey and 8 m respectively.
#### 1.9.2.4
For Type I-D and I-E of Group I construction and all types of Group II construction, the maximum permissible height of the building shall be 3 storeys or 11 m for values of two times the sum of the width of the front road and the front open space not less than 13.6 m.
#### 1.9.2.5
For applying the provisions of Sections 1.9.2.1 to 1.9.2.4, the width of the front road for the layouts shown in Figures 3.1.2(b), (c), (d), (e) and (f) where the plot abuts more than one road, shall be taken as the average of the widths of the abutting roads.
#### 1.9.2.6
For buildings more than six storeys or 20 m high, the following arrangements shall be provided:
* (a) Lifts of adequate size, capacity and number as per provisions of this Code.
* (b) Adequate fire protection and firefighting arrangements shall be as per provisions of this Code.
* (c) Adequate emergency fire escape stair depending upon the type of occupancy and occupancy load as per provisions of this Code.
* (d) For buildings with unlimited height (UL) provisions of Table 3.1.8 shall be mandatory.
**Table 3.1.8: Minimum Separation Distance for Buildings of Unlimited Height**
| **Occupancy** | **Frontage (m)** | **Rear (m)** | **Side (m)** |
| ------------------------------------------------------------- | ----------------------------- | ------------ | ------------ |
| Residential | 4.0 | 6.0 | 4.0 |
| Business, Mercantile. | 6.0 | 6.0 | 6.0 |
| Educational, Institutional
for care, Medical facilities. | 6.0 | 6.0 | 6.0 |
| Others | As per provision of this Code | | |
#### 1.9.2.7
For buildings in the vicinity of airports or aerodromes, the height shall be limited by the requirements of the civil aviation authority, city or area development authority or other concerned agencies of the Government.
#### 1.9.2.8
Where more than one construction type is permitted within a building as per provision of this Code among them the lowest fire resistance rated construction type shall be applicable for FAR allotment, and lowest fire resistance rating shall be applicable for the whole structure.
#### 1.9.2.9
For road width above 8.8 m, the building form shall be contained within the pyramid formed by the sky exposure planes on all four sides or as many sides it has, following the guidelines of Figure 3.1.4.
### **1.9.3 Area Limitations based on FAR**
#### 1.9.3.1
Fire separation distance in terms of building setback and building occupancy type and construction type shall govern the FAR to restrict fire hazard volume. FAR shall be decided by the development authorities having jurisdiction.
#### 1.9.3.2
For Occupancy in which unlimited FAR is permitted, the minimum open space requirements specified in Table 3.1.8 shall be applicable.
#### 1.9.3.3
For the purpose of calculating FAR, the area of any floor including basement, of which at least two-third is used exclusively for car parking and the remaining onethird is used for purposes such as mechanical plant room, electrical substation, security cabin, reception booth, water tank, pump house, stairs, lifts and which are accessory to the main occupancy, shall be excluded from the calculation of the total floor area of the building.
#### 1.9.3.4
For area with high public transport accessibility and high FAR the requirement for residential private parking should not be more than one car for every four dwellings or as per guidelines of the authority having jurisdiction.
#### 1.9.3.5
In specifying FAR for a zone or an area, the city or area development authority shall follow the guidelines of Appendix-A (Development Control) and shall take into consideration the following:
* (a) Proximity to Public/Mass Transport network
* (b) Availability of Urban social infrastructure including urban open spaces
* (c) Environmental balance
* (d) Adequacy of present and proposed Utility services
* (e) Occupancy group and land-use permitted by master plan
* (f) Type of construction
* (g) Population density of the area
* (h) Width of approach roads
* (i) Traffic density in the approach roads
* (j) Local fire-fighting facilities
* (k) Parking facilities
![Limiting envelope for stepped tower structures]()
## **1.10 Off Street Parking Spaces**
### 1.10.1
Off street parking requirement for a building or an area shall be decided by the development authority having jurisdiction. A suggestive guideline for off-street parking given in Appendix F might be followed.
### 1.10.2
Sloping drive way steeper than 1 vertical to 8 horizontal shall not be credited as a walking ramp. When a sloping surface used for both driveway and walking ramp shall be demarcated and the minimum width and sloping ratio of walkways shall be as per provisions of this Code. Sloping driveway entering below grade level shall be protected to prevent water flow into any level that they lead to.
## **1.11 Street Encroachment**
No part of any building shall project beyond the property line or building line established by the provisions of this Code into the street, except the following:
* (a) Below Grade: The footing of the boundary wall adjacent to the street may encroach on to the street land not more than 0.3 m and shall rest at least at a depth of 1.5 m below grade.
* (b) Above Grade: Marquee, canopy or other temporary cantilever type projection from buildings of business and mercantile occupancy may project on the footpath of a road, provided that no part of such projection is below a height of 3 m from the footpath level and that the outer edge of the canopy is at a minimum clear horizontal distance of 0.25 m from the road side edge of the footpath. The canopy shall be so constructed as to be readily removable without endangering the building structure. No canopy shall project into a street without a footpath. Such canopies shall not project over Mandatory Open Space (MOS). Under no circumstances shall the top of the canopy be used by any floor of the building.
## **1.12 Community Open Space And Amenities**
Community open space for an area or a building shall be decided by the development authority having jurisdiction. Where no such guide line exists or yet to be developed, the guidelines of Sections A.4 and A.5 of Appendix A and Sec B.3.2 of Appendix B shall be applicable.
## **1.13 Minimum Standard Of A Dwelling**
Minimum standard of a dwelling shall be decided by the development authority having jurisdiction.
## **1.14 Requirements of Parts of Buildings**
### **1.14.1 Plinth and Formation Levels**
The plinth and formation levels of the building and the plot shall conform to the requirements of Sec 1.5.3.
### **1.14.2 Room Dimensions**
#### 1.14.2.1 Ceiling heights
* (a) All habitable rooms in non-air-conditioned residential, business and mercantile buildings, apart from kitchen, store room, utility room, box room and garage, shall have a ceiling height not less than 2.75 m measured from the finished surface of the floor to the underside of the finished ceiling, or false ceiling. A maximum of one-third of the floor area of such habitable rooms may, however, have a minimum ceiling height of 2.44 m. For air-conditioned rooms in such buildings, the minimum ceiling height shall be 2.44 m.
* In the case of pitched roof without a horizontal ceiling the lowest point of the finished ceiling shall be at least 2 m above the finished surface of the floor and the average height of the ceiling shall not be less than 2.44 m.
* (b) The minimum clear head room under the ceiling, folded plate, shell etc. and under the false ceiling or duct in an air-conditioned room shall not be less than 2.44 m. The minimum clear distance between the floor below and the soffit of a beam shall not be less than 2.15 m.
* (c) The requirements of ceiling height for buildings of occupancy other than residential and business and mercantile shall be as follows:
**Table 3.1.9: Minimum Ceiling Heights for Different Occupancies**
| **Occupancy** | **Minimum Ceiling Height** |
| ------------------------------------------------------- | ---------------------------------------------------------------------------- |
| Educational, Institutional, Health
Care, Assembly. | 3 m for non-air-conditioned and 2.6 m for air-
conditioned buildings. |
| Industrial, Storage, Hazardous. | 3.5 m for non-air-conditioned and 3.0 m for air-
conditioned buildings. |
#### 1.14.2.2 Room sizes
All habitable rooms used for sleeping and other purposes of a dwelling unit shall not be less than 9.5 m² of net floor area with a minimum width of 2.9 m and shall comply with indoor air quality requirement as per provisions of this Code. Other non-habitable rooms in the dwelling unit shall have a minimum area of 5 m² with a minimum width of 2 m.
### **1.14.3 Kitchen**
#### 1.14.3.1
The minimum clear height of kitchen measured from the finished surface of the floor to the finished ceiling shall be 2.75 m, except for any floor trap of the upper floor which shall have a minimum clearance of 2.15 m above the finished floor. The minimum clear height of kitchen shall be 2.15 m where mechanical exhaust is installed.
#### 1.14.3.2
The minimum floor area of kitchen without provision for dining shall be 4 m² with a minimum width of 1.5 m. The minimum floor area of a kitchen which is intended to provide dining or occasional sleeping space shall be 7.5 m² with a minimum width of 2.2 m.
#### 1.14.3.3
Every kitchen shall be provided with a kitchen sink or other means for washing utensils. The waste water shall be discharged into the waste water pipe or drain as per provisions of Part 8.
#### 1.14.3.4
The floor of the kitchen shall be slip-resistant and water tight.
#### 1.14.3.5
Every kitchen shall be provided with window having a minimum area of 1 m² which shall open to the exterior or to an interior open space of adequate dimensions complying with Sec 1.19.
#### 1.14.3.6
It is recommended that all kitchens should be designed as accessible kitchens for people with disability considering the door width, accessible route, turning clearance within the kitchen, counter heights, placement of fixtures, knee and toe clearances under counters and other relevant criteria in compliance to the guidelines of Appendix D.
### **1.14.4 Bathroom and Toilets**
#### 1.14.4.1
The height of any bathroom, toilet or water closet shall not be less than 2.15 m measured from the finished floor surface to the finished ceiling or false ceiling or to the lowest point of any trap of the upper floor's plumbing system.
#### 1.14.4.2
The minimum requirement of floor area and width of a bathroom with 3 fixtures, 2 fixtures or single fixture shall conform to the space standards of Table 3.1.10.
#### 1.14.4.3
Details for requirement of adaptable or accessible toilets shall follow the guidelines of Appendix D.
**Table 3.1.10: Bathroom Space Standards**
| **Facility** | \*\*Minimum Width (m) \*\* | **Floor Area (m****2****)** |
| ------------------------------------- | -------------------------- | -------------------------------------- |
| Water closet + bathing + hand washing | 1.25 | 3.00 |
| Water closet + bathing | 1.00 | 2.80 |
| Bathing only | 1.00 | 1.50 |
| Water closet only | 1.00 | 1.20 |
| Adaptable toilets | 1.50 | as per Appendix D |
#### 1.14.4.4
No bathroom or toilet containing water closet shall open directly into any kitchen or cooking space by a door, window, ventilator, fanlight or any other opening. Every such bathroom or toilet shall have a door completely shutting it off from the exterior.
#### 1.14.4.5
Every bathroom, toilet and water closet shall be located against an exterior wall or wall on the interior open space (see Sec 1.8.10), except where they are ventilated through an interior lighting and ventilation shaft. Such interior lighting and ventilation shafts shall have the minimum dimensions specified in Table 3.1.11 for different heights of buildings. In addition, shafts for buildings exceeding 6 storeys or a height of 20 m shall be mechanically ventilated. All shafts must be accessible at the ground floor level for cleaning and servicing purposes.
**Table 3.1.11: Minimum Dimensions of Lighting and Ventilation Shaft**
| **Building (No. of Stories)** | **Building Height (m)** | **Minimum Net Cross-Sectional Area of Shaft (m****2****)** | **Minimum Width of Shaft (m)** |
| ----------------------------- | ----------------------- | --------------------------------------------------------------------- | ------------------------------ |
| Up to 3 | Up to 11 | 1.50 | 1.00 |
| 4 | 14 | 3.00 | 1.20 |
| 5 | 17 | 4.00 | 1.50 |
| 6 | 20 | 5.00 | 2.00 |
| Over 6\* | Over 20 | 6.50 | 2.50 |
* Mechanical ventilation of the shaft shall be provided for buildings over 6 stories high.
Shaft dimensions shall conform to mechanical design considerations.
#### 1.14.4.6
Floors of bathrooms, toilets or water closets shall be treated with water repellent material and shall be water tight. All bathroom walls or partitions shall be treated with non-absorbent water repellent smooth impervious finish material to a height of not less than 1 m above the finished floor level. The floor shall be sloped gently towards gratings or openings of the floor traps.
#### 1.14.4.7
All public buildings shall have adaptable toilet as per requirement of the development authorities having jurisdiction. Each dwelling unit shall have at least one adaptable toilet. The details of such toilet shall comply with requirements of Appendix D (Universal Accessibility).
### **1.14.5 Stairways**
#### 1.14.5.1 Limiting Dimensions
The minimum width of the staircase for various occupancies shall be as specified in Table 4.3.6 of Part 4.
#### 1.14.5.2
Sum of two risers and one tread excluding nosing dimension shall not be less than 610 mm and not more than 648 mm. All Risers and Treads shall be identical in consecutive two flights starting from one floor to another floor. Difference between two consecutive risers or treads shall not be more than 5 mm. The combination of riser and treads shall comply with Table 4.3.4 Chapter 3, Part 4.
#### 1.14.5.3
The maximum flight height between landings shall not be more than 3660 mm. For Assembly occupancy maximum flight height between landings shall not be more than 2440 mm.
#### 1.14.5.4
The minimum clear head room between flights of a staircase shall be 2.15 m. The clear head room may be reduced to 2.03 m for not more than three flights in any staircase.
#### 1.14.5.5
The minimum clear height of any passage below a landing providing access to non-habitable and service spaces shall be 2.03 m. The minimum clear height of all other passages and spaces below a landing shall be 2.15 m.
#### 1.14.5.6
Handrails shall have a minimum height of 0.9 m measured from the nose of stair to the top of the handrail.
### **1.14.6 Mezzanine Floor**
#### 1.14.6.1
Each mezzanine floor area in a space shall not exceed one-third of the main floor area. The area of the mezzanine shall be included in calculating the FAR.
#### 1.14.6.2
The clear headroom both over and under the mezzanine floor shall be at least 2.2 m.
#### 1.14.6.3
The lighting and ventilation of the space both over and under the mezzanine floor shall not be obstructed in any way.
### **1.14.7 Lofts**
#### 1.14.7.1
Space under slope roof termed lofts shall not be used as a habitable space where minimum ceiling height is less than the requirement but more than 1.5 m.
#### 1.14.7.2
The minimum ceiling height requirements for various rooms specified under Sections 1.14.2.1, 1.14.2.2, 1.14.3 and 1.14.4 shall be maintained under the loft.
#### 1.14.7.3
A maximum of 25% of the floor area of any room may be covered by a loft, except bathrooms, toilets, water closets, store rooms and corridors where the whole area may have an overhead loft.
#### 1.14.7.4
The loft shall not interfere with the lighting and ventilation of any room.
### **1.14.8 Cabins or Chambers**
#### 1.14.8.1
Cabins or Chambers created by removable partitions on open floor shall have a minimum area of 3m2 .
#### 1.14.8.2
Clear passages at least 0.75 m wide (or as stipulated in Part 4) shall be maintained between the cabins leading to a means of exit which shall in no case be further than 16 m from any cabin.
#### 1.14.8.3
A clear gap of at least 300 mm shall be maintained between the top of the partition walls enclosing the cabin and the ceiling, unless the cabin is exposed to the exterior deriving natural light and ventilation or is artificially lighted and ventilated.
### **1.14.9 Store Room**
A store room provided in a dwelling unit of a residential building shall have a minimum area of 1.5 m2 with a minimum width of 1 m. The clear height of the store room shall not be less than 2.2 m.
### **1.14.10 Private Garage**
Private garage in residential occupancy A1 and A2 building shall have a minimum clear height of 2.03 m. The minimum area of the parking stall in a garage shall be decided in accordance with the provision of Sec F.7.1 of Appendix F.
### **1.14.11 Basement**
Any underground floor of a building wholly or partially below formation level shall be called a basement and shall satisfy the requirements of the following sections.
#### 1.14.11.1
Subject to the provision of Sec 1.9.3.3, the area of the basement shall be included in the calculation of FAR.
#### 1.14.11.2
The walls and floors of the basement shall be damp-proof and water-proof as per provision of this Code. The basement shall be protected against surface and subsurface waste water intrusion.
#### 1.14.11.3
The basement shall be lighted and ventilated as per provision of this Code.
#### 1.14.11.4
The staircases of a building serving above grade level also entering into below street floor level shall be enclosed by barrier wall with two door smoke proof vestibule shall have minimum 2 hours fire resistance time.
#### 1.14.11.5
Ramp provided as walkways shall not be steeper than 1 vertical in 8 horizontal.
#### 1.14.11.6
The clear height of the basement below soffit of beams shall not be less than 2.03 m.
### **1.14.12 Entrance to the Building**
All buildings shall have a covered entrance or other covered area for callers waiting at the door. The main entrance door to the building shall not open into an uncovered exterior. All public buildings shall have universal accessibility as per provisions of Appendix D of Part 3.
### **1.14.13 Roof Drainage**
#### 1.14.13.1
The roof of a building shall be constructed in such a manner that rain water is drained freely away from the building without causing dampness of the roof or the walls of the building or of an adjacent building.
#### 1.14.13.2
Water from the roof shall not be discharged into the adjacent property or street.
#### 1.14.13.3
For one or two storied buildings with flat or pitched roof, rain water may be discharged directly to the ground, in which case the roof shall have extended eaves or cornices to direct the water away from the walls.
#### 1.14.13.4
For other buildings, gutters or parapets shall be provided to direct the water to the piping of an adequate rain water drainage system.
#### 1.14.13.5
The roof shall be impermeable or shall be treated with an impervious material to make it effectively water tight. Flat concrete roofs shall be topped with an impervious layer of lime concrete or other effective means of waterproofing. All flat roofs shall be sloped gently towards gutters, gratings or mouths of the rain water drainage pipes.
#### 1.14.13.6
For sustainable development, building may have rain water harvesting system as stipulated in Part 8, Chapter 7.
### **1.14.14 Parapet**
All accessible flat roofs shall be enclosed by parapets or guardrails having a height of at least 1 m. All such parapets and guardrails shall be designed to withstand the lateral forces due to wind and occupancy in conformity with the provisions of Part 6 of this Code.
### **1.14.15 Septic Tank**
A septic tank shall be provided within the premises for disposal of sewage, whether any public sewer is available or not. The location, design and construction of the septic tank shall conform to the requirements of this Code.
## **1.15 Landscaping**
### 1.15.1
Plantation of trees and shrubs within the open spaces of a plot aimed at enhancing the environmental quality of the building shall comply with the requirements of this Section.
### 1.15.2
Trees and shrubs shall be planted judiciously to meet the requirements of shade and sunshine, to control noise and dust, to provide privacy and to improve visual quality, without jeopardizing natural ventilation and lighting of a building.
### 1.15.3
Species of trees shall be so chosen and planted that their roots do not endanger the building foundation and their branches do not interfere with the building superstructure. This shall be achieved by maintaining sufficient distance between the trees and the building depending on the species of the tree.
## **1.16 Damp-Proofing and Waterproofing**
Foundation, floor slabs, walls and roof of a building shall be damp proof, water proof and weather proof in accordance with the provisions of Part 6 of this Code.
## **1.17 Existing Buildings**
### 1.17.1
Existing buildings and structures in their present occupancy condition shall not be required to be in full compliance with all the requirements of this Part of this Code. Additions or alterations to such existing buildings or change of use thereof shall not be permitted if such addition, alteration or change of use or occupancy is likely to render the building more hazardous with respect to fire safety, life safety and sanitation than it was before.
### 1.17.2
Any horizontal or vertical extension of an existing building or any change of use thereof shall subject the altered building or occupancy to the provisions of this Code for a new building. The building together with the additions and changes shall not exceed the height, area and open space requirements for new buildings specified in this Code.
### 1.17.3
All buildings and structures, both new and existing shall be maintained in a safe and sanitary condition as provided for in this Code. To determine compliance with this requirement, the Authority may cause the building or structure to be periodically inspected.
### 1.17.4
Any proposed change in an existing building or structure shall have to satisfy the requirements set forth in Part 6 of this Code.
## **1.18 Buildings and Areas of Historical or Architectural Value**
### 1.18.1
Buildings and areas of Historical value are part of our heritage and cultural inheritance and should therefore be protected. Similarly buildings and works under the jurisdiction of and identified by the Authority as having architectural value shall also be protected. The identification, listing and classification of all such buildings and places of historic or architectural values shall follow the guidelines of Chapter 3 of Part 9, Section 1.5 of Part 1 and Section 3.14 of Part 2.
### 1.18.2
Repairs, alterations and additions necessary for the preservation, restoration, rehabilitation, continued use or adaptive reuse of such historic buildings and structures, and of buildings and works of architectural value may be exempted by the Authority from having to be in full compliance with all the requirements of this Code, provided that the restored building or structure will be no more hazardous, if any, than the existing conditions in terms of life safety, fire protection and sanitation. All such buildings and places shall comply with the provisions for conservation of heritage buildings or area of Part 9.
## **1.19 Ventilation, Lighting and Sanitation**
### 1.19.1
All rooms and interior spaces designated for human occupancy shall be provided with means of natural or artificial lighting and natural or mechanical ventilation as per provisions of this Code. At least one side of all habitable rooms shall be exposed to an exterior or an interior open space or to a balcony or verandah exposed to an open space.
### 1.19.2
All buildings shall have water and sanitation facilities as per provisions of this Code.
### 1.19.3
Every kitchen shall have facility for washing of utensils.
### 1.19.4
Every building or independent unit thereof shall be provided with at least one water closet.
### 1.19.5
All naturally ventilated and illuminated interior spaces, staircases and other areas of human occupancy in a building shall have windows or ventilators opening directly to the exterior or an interior open space or to a verandah. Ventilation of bathrooms may also be achieved through ventilation shafts as provided for in Sec 1.14.4.5.
### 1.19.6
All habitable and non-habitable spaces within a building shall have the following minimum aggregate area of openings in the exterior wall, excluding doors, expressed as percentage of the net floor area:
**Table 3.1.12: Dimension of Openings for Different Uses**
| Space | Percent of Net Floor Area |
| --------------------------------------------------------------------------- | ------------------------- |
| Habitable rooms such as those used for sleeping, living, study, dining etc. | 15 |
| Kitchens\* | 18 |
| Non-habitable spaces such as bathrooms, store, staircase and other utility | 10 |
* Minimum height from the window sill of a kitchen shall be 450mm above cooking range. Air flow on cooking range shall be restricted.
#### 1.19.6.1
An enclosed staircase shall have windows not less than 1 m² in area on exterior walls of every landings as per provisions of this Code.
#### 1.19.6.2
Toilet and bathroom windows shall open to the exterior or an approved ventilation shaft and the operable area shall not be less than 1 m².
### 1.19.7
The required minimum average intensity of illumination in a habitable space at a height of 750 mm above the floor level shall be 65 lux. Any point in a room more than 7 m away from an exterior window shall be considered to be not illuminated by daylight unless measurement of illumination gives an intensity of 65 lux or more.
#### 1.19.7.1
The required intensity of illumination for various tasks in a building shall be as specified in Chapter 1 of Part 8.
#### 1.19.7.2
Whenever the illumination achieved by daylight is not sufficient or occupancy at night is necessary, artificial lighting shall be installed to supplement daylight, or to provide the required night lighting, in accordance with the provisions of Chapter 1 of Part 8.
### 1.19.8
Protected openings, when and where are installed shall not be normally operable form the inside of a building. Such openings however, shall not be credited towards meeting any ventilation requirements.
### 1.19.9
The requirements of opening areas specified in Sec 1.19.6 shall suffice for ventilation provided that the windows or ventilators forming the opening are operable. When part of a window area is made of fixed glazing, only the operable portion shall be counted in aggregating the opening area.
#### 1.19.9.1
To achieve the desired indoor air quality by natural means, an interior space shall preferably have minimum two openings on two different walls where the opening acting as inlet must be an exterior wall and the summation of the net opening area on walls shall not be less than 5% of the net floor area thereof.
#### 1.19.9.2
Mechanical ventilation, when provided, shall conform to the requirements of Chapter 3 of Part 8.
## **1.20 Air-Conditioning and Heating**
When air-conditioning and heating system are installed, an indoor air quality shall be maintained as per provisions of Chapter 3 Part 8.
## **1.21 Provision of Lifts and Escalators**
Wherever required by this Code or desired by the owner for comfort, lifts and escalator facilities shall be planned, designed and installed in accordance with the provisions of Part 4 and Part 8 of this Code. The minimum size of a lift lobby shall be 1.5 m x 1.5 m. For accessible lift guidelines of Appendix D shall be applicable.
## **1.22 Sound Insulation**
Acoustical design of a building to attain the desired noise levels shall be performed in accordance with the provisions of Chapter 4 Part 8.
## **1.23 Thermal Insulation**
Thermal comfort in a building shall be achieved through adequate ventilation and thermal insulation of walls and roof.
## **1.24 Lightning Protection of Buildings**
Lightning protection measures shall be installed on all buildings whose exposure conditions indicate the likelihood of lightning strike and consequential hazard to life and property. The requirement of lightning protection systems shall be assessed and they shall be designed and installed in accordance with the provisions of Chapter 2 Part 8.
## **1.25 Rat Proofing and Termite Proofing Of Buildings**
Rat proofing and termite proofing measures shall be undertaken on the basis of the degree of protection desired from rats and termites. Any chemical used for the control of rats and termite shall be free from environmental hazards. Periodic inspections shall be undertaken for effective protection against rats and termites.
## 1.26 Requirements For Buildings In Flood Prone and Coastal Regions of Bangladesh\*\*
The specifications of this Section shall be applicable to all buildings located in the flood or surge prone areas in addition to other requirements of this Code.
* (a) The planning and development control authority of the city, township, municipality or region where this Code is intended to be applied shall delineate any area having a potential for being flooded under at least 1 m deep water due to flooding as Flood Prone Area (FPA). The provisions of Sec 1.26.1 shall be applicable to areas designated as FPA. There shall be a design flood level in the FPAs which shall be recommended by the Authority to be used in interpreting the provisions of this Section.
* (b) Similar delineation shall be made in the coastal regions on the basis of expected occurrence of a surge or wave run-up of 1 m or higher. Such areas shall be designated as Surge Prone Area (SPA). The provisions of Sec 1.26.2 shall be applicable to buildings located in the SPAs. There shall be a design surge height in the SPAs which shall be recommended by the Authority to be used in interpreting the provisions of this Section.
### **1.26.1 Flood Prone Areas**
#### 1.26.1.1 Elevation
The habitable floors of a building located in the flood prone area shall be elevated above the design flood level. Buildings up to two storeys high shall have accessible roof with an exterior stair. Buildings having three storeys or more height, the floor immediately above the design flood level shall be accessible with an exterior stair.
Exceptions:
* (a) Except for Occupancy A (Residential), any occupancy may have floors below the design flood level in accordance with the provisions of Sec 1.26.1.3.
* (b) Floors which are used only for building access, exits, foyers, storages or parking garages may be located below the design flood level in accordance with the provisions of Sec 1.26.1.2.
#### 1.26.1.2 Enclosures below design flood level
There shall be no enclosed space below the design flood level except for building access, exits, foyers, storage and parking garages. There shall be vents, valves or other openings in the walls of the enclosed spaces which shall equalize the lateral pressure of the water. The bottom of such openings shall not be higher than 300 mm above the finished grade. There shall be at least two openings for each enclosure in a building. The total net area of openings for an enclosure shall be at least 0.4 m2 or 7 percent of the floor area of the enclosure, whichever is greater.
#### 1.26.1.3 Flood-resistant Construction
Floors constructed below the design flood level under the provisions of Exceptions in Sec 1.26.1.1 shall comply with the following requirements:
* (a) Floors and exterior walls of such floors shall have a construction impermeable to the passage of water.
* (b) Structural components of such floors shall be capable of resisting the hydraulic and buoyant forces resulting from the occurrence of floods at the design flood level. Design requirements in such cases are specified in Chapter 1, Part 6.
* (c) Vents, openings and valves provided below the design level shall have water-tight closures capable of resisting any structural forces resulting from the occurrence of the design flood.
* (d) Penetrations made for electrical, mechanical or plumbing installations shall be made water-tight to prevent any penetration of flood water. Sewerage systems having opening below the design flood level shall have a closure device to prevent backwater flow during the occurrence of floods.
### **1.26.2 Surge Prone Areas**
#### 1.26.2.1 Elevation
The habitable floor of any building in a surge prone area shall not be located below the design surge height. For buildings of height two storeys or less the roof shall be accessible with an exterior stair. For buildings having three storeys or higher, the floor immediately above the design surge level shall be accessible with an exterior stair.
Exception:
Footing, mat or raft foundations, piles, pile caps, columns, grade beams and bracings may be constructed below the design surge height.
#### 1.26.2.2 Enclosures below Design Surge Height
Spaces of a building in the SPAs below the design surge height shall not obstruct any flow of water during the occurrence of surge.
Exception:
Structural or non-structural members serving as entries or exits may be constructed below design surge height.
#### 1.26.2.3 Foundations
Foundations of the buildings erected in the SPA's shall be located well below the ground level so that they are protected from erosion or scour during the occurrence of surge. If piled foundations are used, they shall be designed to withstand with adequate factor of safety and the loss of support due to scour. Design of the foundations shall conform to the requirements of Chapter 3 Part 6.
## **1.27 Requirements for Buildings In Other Disaster Prone Areas**
In hilly region, authority shall ask for a special site drainage plan conforming to the area drainage network before approval of any building work. This shall apply for all buildings to be constructed in hilly areas where there is the danger of failure of slopes, including mudslides, flash floods and soil erosion. Such failures may occur in hilly areas, where the angle of slope is greater than 30°. Prevention of failure of slopes shall be achieved by the following measures:
* (a) Retaining walls to prevent soil erosion as per provisions of Part 6 of this Code.
* (b) Weep holes to allow water pressure balancing from the water logged soil on the retaining wall.
* (c) Adequate site drainage respecting the natural topography of the site and surrounds.
* (d) Use of vegetation to retain the top soil and bonding quality of the soil.
* (e) Protection of soil by catchment pools to prevent soil erosion due to discharge from elevated level onto the ground.
## 1.28 Special Provision For Storage of Dangerous Goods and Their Classification\*\*
### 1.28.1
Any substance including mixtures and solutions shall be assigned to one of the following Classes for any Occupancy if it crosses the limits of exempted quantities as per Table 3.2.5 of Part 3, Section 2. Some of these classes are subdivided into divisions also. The numerical order of the classes or divisions is not the representative of the degree of danger. These classes including their divisions are listed below:
**Class 1: Explosives**
* Division 1.1: Substances and articles which have a mass explosion hazard. Division 1.2: Substances and articles which have a projection hazard but not a mass explosion hazard.
* Division 1.3: Substances and articles which have a fire hazard and either a minor blast hazards or a minor projection hazards, but not a mass explosion hazard.
* Division 1.4: Substances and articles which present no significant hazard.
* Division 1.5: Very insensitive substances which have a mass explosion hazard. Division 1.6: Very insensitive substances which do not have a mass explosion hazard.
**Class 2: Gases**
* Division 2.1: Flammable gases
* Division 2.2: Non-flammable, non-toxic gases
Division 2.3: Toxic gases
**Class 3: Flammable Liquids**
* **Class 4: Flammable Solids; Substances Liable to Spontaneous Combustion; Substances which, in contact with Water, Emit Flammable Gases:**
* Division 4.1: Flammable solids, self-reactive substances and solid
* Division 4.2: Substances liable to spontaneous combustion
* Division 4.3: Substances which, in contact with water, emit flammable gases
**Class 5: Oxidizing Substances and Organic Peroxides**
Division 5.1 Oxidizing substances
Division 5.2 Organic peroxides
**Class 6: Toxic and Infectious Substances**
Division 6.1: Toxic substances
Division 6.2: Infectious substances
**Class 7: Radioactive Material**
**Class 8: Corrosive Substances**
**Class 9: Miscellaneous Dangerous Substances and Articles**
The quantity and procedure for storage, merchandising, handling, processing, packaging, transportation, shipment and uses of all dangerous goods of above classification shall be regulated as per guidelines of Explosive Act and other relevant Acts and as per rules of Bangladesh Shipping Corporation for safe handling of container for dangerous goods. The signs and symbols for all such goods shall comply with the requirements of Bangladesh Shipping Corporation’s guidelines.
### **1.28.2 HS Code, Proper Shipping Names and UN Numbers**
First Schedule of Bangladesh customs tariff that is Harmonized System code shall be used for the description of any substances and its corresponding UN number shall be used for proper shipping name and for the classifications of dangerous goods. The storage and use of all such substances and goods shall be controlled as per provision of this Code and explosive control act.
## **1.29 List of Related Appendices**
Appendix A Development Control and Planning Appendix B Minimum Standard Housing Appendix C Cluster Planning Appendix D Universal Accessibility Appendix E Building Types Appendix F Road Hierarchy, On-street and Off-street Parking
# Chapter 2: Classification of Buildings Based on Occupancy
Source: https://docs.sayed.app/bnbc/part-3-general-building-requirements/chapter-2-classification-of-buildings-based-on-occupancy
## **2.1 Occupancy Classification**
### 2.1.1
Every building or portion thereof and land-use shall be classified according to its use or the character of its occupancy as a building of Occupancy A, B, C, D, E, F, G, H, I, J, K, L or M as defined below:
Occupancy A: Residential Occupancy B: Educational Occupancy C: Institution for care Occupancy D: Health Care Occupancy E: Business Occupancy F: Mercantile Occupancy G: Industrial Occupancy H: Storage Occupancy I: Assembly Occupancy J: Hazardous Occupancy K: Garages Occupancy L: Utilities Occupancy M: Miscellaneous
### 2.1.2
Utilities under Occupancy L is incidental to operation in all other type of occupancy except Occupancy J shall be considered as non-separated use of the main occupancy but shall be taken special safety measure as per provision of this Code.
### 2.1.3
Any occupancy or use type not mentioned specifically in Table 3.2.6 (A-Z list) or elsewhere in this Code shall be classified by the Board of Appeals under the occupancy group to which its use most closely resembles, considering the life safety and fire hazard.
### 2.1.4
Each occupancy group shall be subdivided as detailed in the following sections. The detail classification including mixed occupancy provided in the Table 3.2.6 (A-Z list) is non-exhaustive. If there is any use or character of occupancy in a building which is not mentioned here, it shall be classified as per provision of Sec 2.1.3 of this Chapter.
### **2.1.5 Occupancy A: Residential Buildings**
This occupancy type shall include any building or portion thereof providing sleeping and living accommodations to related or unrelated groups of people, with or without independent bathroom, cooking or dining facilities, except any building classified under Occupancy C or D. This Occupancy shall be subdivided as follows:
#### 2.1.5.1 Single Family Dwelling (A1)
These shall include any building, row type or semi-detached or detached from neighboring buildings by distances required by this Code and having independent access to the plot, which is used as private dwelling by members of a single family.
#### 2.1.5.2 Two Family Dwelling (A2)
These shall include any building, row type or semi-detached or detached from neighboring buildings by distances required by this Code and having shared or independent access for two families and having facilities for living, cooking and bathroom facilities independent of each other.
#### 2.1.5.3 Flats or Apartments (A3)
These shall include any building or portion thereof which is provided for more than two families, having facilities for living, cooking and bathroom facilities independent of each other.
#### 2.1.5.4 Mess, Boarding Houses, Dormitories and Hostels (A4)
These shall include any building or portion thereof in which sleeping, living accommodations and bathroom are provided for groups of related or unrelated persons, with or without common dining and facilities, and with common cooking under single management control or with individual or group cooking facilities.
#### 2.1.5.5 Hotels and Lodging Houses (A5)
These shall include any building, a portion thereof or group of buildings under single management, in which sleeping, living accommodation and bathroom facilities are provided with or without dining facilities but without cooking facilities for adult individuals, is provided for hire on transient or permanent basis.
### **2.1.6 Occupancy B: Educational Facilities**
This occupancy type shall include any building or portion thereof in which education, training and care are provided to children or adults. This Occupancy shall be subdivided as follows:
#### 2.1.6.1 Educational Facilities up to Higher Secondary Level (B1)
These shall include any building or portion thereof used for purposes involving assembly for instruction, education and recreation of more than six persons on regular basis to fulfil the requirement of an academic curriculum approved by the Government up to Higher Secondary (12th Grade), and which is not covered by occupancy I.
#### 2.1.6.2 Facilities for Training and for Above-Secondary Level (B2)
These shall include any building or portion thereof used for purposes involving assembly for instruction, education, training and recreation of more than six persons, and which is not covered by occupancy I and B1.
#### 2.1.6.3 Pre-School Facilities (B3)
These shall include any building or portion thereof used for purposes involving care, recreation and education of children more than six in number, who have not yet reached the age to attend the school.
### **2.1.7 Occupancy C: Institution for Care**
Buildings classified under this occupancy shall include those used for purposes of institutional care of the occupants, such as detention for correctional or penal purposes, medical or nursing care of persons suffering from illness or infirmity due to mental condition, or accommodation of children or minor, where the personal liberty of the inmate is restricted. These buildings shall ordinarily provide accommodation for sleeping, dining and other provisions approved by the authority for the occupants. This occupancy shall be subdivided as follows:
#### 2.1.7.1 Institution for Care of Children (C1)
These shall include any building or portion thereof or group of buildings under single management used as an institution for the full time care of children or minor, each providing accommodation for sleeping, dining and other provisions approved by the authority for more than six children.
#### 2.1.7.2 Custodial Institution for Physically Capable Adults (C2)
These shall include any building or portion thereof or group of buildings under single management used for purposes of full time care and custody of adult or mentally disabled persons but physically capable of responding to emergency.
#### 2.1.7.3 Custodial Institution for the Incapable Adults (C3)
These shall include any building or portion thereof or group of buildings under single management used for purposes of full time care and custody of persons physically or mentally incapable of responding to emergency.
#### 2.1.7.4 Penal and Mental Institution for Children (C4)
These shall include any building or portion thereof or group of buildings under single management used for housing children under restraint, or who are detained for penal and corrective purposes, in which personal liberty of the inmates is restricted.
#### 2.1.7.5 Penal and Mental Institution for Adults (C5)
These shall include any building or portion thereof or group of buildings under single management used for housing persons under restraint, or who are detained for penal and corrective purposes, in which personal liberty of the inmates is restricted.
### **2.1.8 Occupancy D: Health Care Facilities**
Buildings under this Occupancy group shall include those used for purposes of providing medical care, diagnostic facilities and treatment to persons suffering from physical discomfort, in which sleeping accommodation may or may not be provided. This Occupancy shall be subdivided as follows:
#### 2.1.8.1 Normal Medical Facilities (D1)
These shall include any building or portion thereof or group of buildings under single management in which essential medical facilities having surgery, emergency and casualty treatment facilities, general or specialized medical and other treatment are provided to persons suffering from physical discomfort.
#### 2.1.8.2 Emergency Medical Facilities (D2)
These shall include any building or portion thereof used for purposes of providing essential medical facilities having surgery, emergency, casualty treatment facilities, general or specialized medical and other treatment is provided to persons suffering from physical discomfort. This Type shall be equipped and designated to handle post disaster emergency, by construction it is required to remain operational during and after disasters, built as a part of disaster preparedness program.
### **2.1.9 Occupancy E: Business**
These shall include any building or portion thereof which is used for any business transaction other than mercantile. This Occupancy shall be subdivided as follows:
#### 2.1.9.1 Office (E1)
These shall include any building or part thereof which is used for paper works, documentations, only display of samples of Products but not for direct sale, maintaining accounts and records for administrative or consulting services, banking or activities for business purposes and professional training.
#### 2.1.9.2 Research and Testing Laboratories (E2)
These shall include any building or portion thereof which is used as research establishment and/or test laboratory involving hazardous materials within the limit of exempted quantity permitted in this Code.
#### 2.1.9.3 Essential Services (E3)
These shall include any building or portion thereof used for purposes of providing emergency services and utilities which are required to remain operational during and after a disaster or other emergency situations.
### **2.1.10 Occupancy F: Mercantile**
This occupancy type shall include any building or portion thereof or group of buildings which is used for display and sale of merchandises. This Occupancy shall be subdivided as follows:
#### 2.1.10.1 Small Shops and Market (F1)
These shall include any building or portion thereof with an area divided or undivided not exceeding 300 m², used for purposes of display and sale of merchandise, either wholesale or retail, with or without incidental storage and service facilities.
#### 2.1.10.2 Large Shops and Market (F2)
These shall include any building or portion thereof with an area divided or undivided more than 300 m² used for purposes of display and sale of merchandise, either wholesale or retail, with or without incidental storage and service facilities.
#### 2.1.10.3 Refueling Station (F3)
These shall include any building or portion thereof used for providing refueling and maintenance without repair services for automobiles which is moderately hazardous in nature.
### **2.1.11 Occupancy G: Industrial Buildings**
Buildings under this Occupancy shall be subdivided on the basis of hazard potential of the contents and the processes of the industry. The hazard shall generally mean the relative danger of the start of fire and the rapidity of its spread, the danger of smoke and gases generated that pose a potential threat to the safety of the occupants of the building. Unless areas with different degrees of hazard are effectively segregated and separated in accordance with the provisions of this Code, the most hazardous area in a building shall govern its classification. This occupancy shall also include facilities for public utility services at the producer or distributor’s end that deals with generation and distribution of utility facilities. Any such building or portion thereof, which is not using hazardous material quantified and categorized in occupancy group J, shall be subdivided as follows:
#### 2.1.11.1 Low Hazard Industry (G1)
These shall include any industrial building in which the contents are of such low combustibility and the processes conducted therein are of such low hazardous nature that danger of self-ignition and self-propagation of fire is nonexistent, the only danger being an onset of fire from external sources with the resulting danger to life and property.
#### 2.1.11.2 Moderate Hazard Industry (G2)
These shall include any industrial building in which the contents are moderately combustible and the industrial processes conducted therein are liable to give rise to a fire which will spread with moderate rapidity, giving off considerable smoke.
### **2.1.12 Occupancy H: Storage Buildings**
Buildings under this Occupancy group shall include any building or portion thereof used primarily for storage or sheltering of goods, wares, merchandises, vehicles or animals. Any such building or portion thereof, which is not used for storing hazardous material quantified and categorized in occupancy group J, shall be subdivided as follows:
#### 2.1.12.1 Low Fire-risk Storage (H1)
These shall include any building or portion thereof which is used for storage of materials or other contents which do not constitute the danger of self-ignition, and in the event of fire the rate of burning shall be less than moderate rapidity.
#### 2.1.12.2 Moderate Fire-risk Storage (H2)
These shall include any building or portion thereof which is used for storage of materials which do not constitute the danger of self-ignition but which in the event of fire will burn with moderate rapidity.
Items which shall be deemed to render a building hazardous are specified in Sec 2.14.3 along with the exempted amount for each item.
### **2.1.13 Occupancy I: Assembly**
Buildings under this Occupancy group shall include any building or portion thereof in which groups of people congregate or assemble for recreation, amusement, social, religious, political, cultural, travel and similar purposes. This Occupancy shall be subdivided as follows:
#### 2.1.13.1 Large Assembly with Fixed Seats (I1)
This occupancy shall include a building or a portion thereof for assembly in a space provided with fixed seats for 1000 or more persons. Assembly buildings under this subdivision may be for theatrical, operatic performances or cinema projection having or not a raised stage, proscenium curtains, scenery loft or projection screen, lighting equipment, projection booth and necessary theatrical and mechanical equipment.
#### 2.1.13.2 Small Assembly with Fixed Seats (I2)
This occupancy type shall include any building or portion thereof primarily meant for use as described for buildings under Occupancy I1, but with fixed seats for less than 1000 persons in a space. These assembly buildings may or may not be provided with a legitimate theatrical stage or related accessories or equipment.
#### 2.1.13.3 Large Assembly without Fixed Seats (I3)
This occupancy type shall include any building or portion thereof for assembly in a space, in which there are no fixed seats, which may or may not be provided with a legitimate stage or theatrical accessories, and which has accommodation for 300 or more persons.
#### 2.1.13.4 Small Assembly without Fixed Seats (I4)
This occupancy type shall include any building or portion thereof primarily intended for use as described in Occupancy I3, but with accommodation for less than 300 persons in a space.
#### 2.1.13.5 Sports Facilities (I5)
This occupancy type shall include any building or portion thereof meant for assembly of spectators for recreational and amusement purpose mainly related to sports.
### **2.1.14 Occupancy J: Hazardous Buildings**
Any Building or portion thereof used as storage, industrial, research and other facilities dealing with hazardous material in excess of exempted quantity defined in the Table 3.2.5 or any micro-biological facilities shall be categorized in this Occupancy group.
Definition of hazard and the amount of such materials which shall be deemed to render a building hazardous are set forth in Sec 2.14.3. This Occupancy shall be subdivided as follows:
#### 2.1.14.1 Explosion Hazard Buildings (J1)
These shall include any building or portion thereof which is used for storage, handling, processing or manufacture of explosive materials and products that have explosion hazard.
#### 2.1.14.2 Chemical Hazard Buildings (J2)
These shall include any building or portion thereof which is used for storage, handling, processing or manufacture of materials and products that are highly corrosive, toxic, poisonous and physically harmful including corrosive and toxic alkalis, acid or other liquids or chemicals, producing flame, fumes, radiation, and explosive, poisonous, irritant and corrosive gases.
#### 2.1.14.3 Biological Hazard Buildings (J3)
These shall include any building or portion thereof which is used for storage, handling, processing or manufacture of materials and products that use biological processes and in which the risk of harmful biological threat to the occupants exist.
#### 2.1.14.4 Radiation Hazard Buildings (J4)
These shall include any building or portion thereof which is used for storage, handling, processing or manufacture of materials and products that use nuclear and radioactive processes and in which the risk of radioactive contamination exists.
### **2.1.15 Occupancy K: Garage**
These occupancy types shall include any building or portion thereof used one or more vehicles having containers of flammable liquid or compressed gas or carrying power or combination of any of these as a supply source for self-propelling are kept for use, sale, rental purpose, storage, repair, exhibition and all those floors of a building or portion thereof in which such vehicles are not separated by suitable cutoff to prevent fire spreading.
#### 2.1.15.1 Parking Garage (K1)
This occupancy type shall include any building or portion thereof used solely for parking Motor Vehicles for a limited period of time.
#### 2.1.15.2 Private Garage (K2)
This occupancy type shall include any building or portion thereof used as store of owner's or tenant's Motor Vehicles for private use for unlimited period of time.
#### 2.1.15.3 Repair Garage and Showrooms (K3)
This occupancy type shall include any building or portion thereof wherein repair of electrical or mechanical system or denting or painting works of body is performed on any type of vehicles and includes associated floor spaces used as office, showrooms, incidental store and parking.
### **2.1.16 Occupancy L: Utility**
This occupancy type shall include any building or portion thereof used to install any type of equipment to provide support service to any building or portion thereof or group of buildings of all occupancy groups and with special provisions for occupancy J.
This shall also include all public and private utility facilities of the consumer’s end that are located within the consumer’s site and all installations are required special care to ensure life and property safety as per provisions of this Code.
### **2.1.17 Occupancy M: Miscellaneous**
Buildings under this Occupancy group shall include special buildings not covered in other Occupancy groups. These Occupancies shall be subdivided as follows:
#### 2.1.17.1 Special Structure (M1)
Any building or structure which is neither listed in the A-Z list nor covered in any occupancy group provided in this Code but unique in character may be categorized in this occupancy by the Board of Appeals. Each and every individual M1 Structure shall be complied with NFPA or equivalent standards for the life and fire safety.
#### 2.1.17.2 Fences, Tanks and Towers (M2)
These shall include fences and boundary walls over 1.5 m high, standalone structures for gravity water tank and towers for telecommunication, power distribution, air-traffic control terminal or observation towers.
## **2.2 Change of Use**
### 2.2.1
Without prior permission from the Authorities having jurisdiction no change shall be made in the type of occupancy or use of any building that would place it in a different occupancy group or in a different subdivision of the same occupancy group. Such changes shall be permitted only when the land use and the building complied with the provisions of this Code and the laws of the land for such group of Occupancy.
## **2.3 Mixed Occupancy**
### 2.3.1
The following occupancies shall not be required to designate as a separated occupancy classification from uses to which they are accessory any occupancy Group other than Occupancy Group J
* (a) Assembly rooms having a floor area not more than 75 m².
* (b) The administrative and clerical offices and similar offices not exceeding 25 Percent of the floor area of the major occupancy and not related to Hazardous Buildings as defined in Occupancy J.
* (c) Administrative offices, gift shops and other similar uses in Occupancy A provided the uses do not exceed 10 Percent of the floor area of the major occupancy.
* (d) Kitchens associated with a dining area.
* (e) Carports having at least two sides entirely open associated with Occupancy A.
### **2.3.2 Forms of Occupancy Separations**
A building is permitted to have multiple occupancy type, each type of occupancy shall be in groups, which may have combination of different occupancies and shall be separated horizontally or vertically or both accordingly as specified in the Table 3.2.1.
### **2.3.3 Types of Occupancy Separation**
The occupancy separations shall be classified as follows:
* (a) Four Hour Fire Resistive: The four hour fire resistive separation wall or slab shall have no unprotected openings therein and shall provide a fire resistance for at least four hour.
* (b) Three Hour Fire Resistive: The three hour fire resistive separation wall or slab shall provide a fire resistance of not less than three hour. The total width of all openings in separation wall of any one storey shall not exceed 25 Percent of the length of that wall in that storey and no single opening shall have an area greater than 12 m². The openings shall be protected with a fire resistance assembly doors or windows providing fire resistance of at least three hour.
* (c) In case of a floor slab having three hour fire resistance rating, the openings on floor slab shall be protected by vertical enclosures extended above and below such floor openings. The walls of such vertical enclosures shall be at least two hour of fire resistance. All openings in such enclosures shall be protected with fire assembly door or window having fire resistance rating of at least one and one-half hour.
* (d) Two Hour Fire Resistive: The two hour fire resistive separation shall be of a construction having a fire resistance rating of not less than two hour. All openings in such separations shall be protected with a fire assembly door or window of a fire protection rating of at least one and one-half hour.
* (e) One Hour Fire Resistive: The one hour fire resistive separation shall be of at least one hour fire protection construction. All openings in such separations shall be protected with a fire protection assembly door or window of at least one-half hour fire resistance.
**Table 3.2.1: Fire Resistance Rating Requirements for Barrier Walls and Floor/Ceiling Assemblies between Separated Occupancies (hours)**
## **2.4 GENERAL REQUIREMENTS OF ALL OCCUPANCIES**
### **2.4.1 Location on Property**
#### 2.4.1.1
All plots for building construction shall have access to a public road from at least one side.
#### 2.4.1.2
Fire separation distance shall be measured from the face of peripheral wall of a building to the adjacent property line. For the purpose of this Section, if a public road adjoining all along a property line shall get the benefit of half of Road width as a part of Fire separation distance. For two or more buildings on the same plot, distances of imaginary lines equidistant from all side of buildings shall be considered as the required fire separation distances.
#### 2.4.1.3
The exterior walls of a building shall have a fire resistance and opening protection as specified in Tables 3.3.1 (a), 3.3.1 (b) and 3.2.3.
#### 2.4.1.4
Any outward projected elements from the peripheral wall of a building line shall be limited to the sunshade line.
#### 2.4.1.5
When openings in exterior walls are required to be protected due to distance from the property line, the aggregate area of such openings shall not exceed 50 Percent of the total area of the wall in each storey.
#### 2.4.1.6
Dwellings separation walls in semi-detached or row type development shall comply with Sec 2.4.3.
### **2.4.2 Allowable Floor Areas**
#### 2.4.2.1
The total area of the building shall comply with Sec 1.8.3 Chapter 1 of this Part.
#### 2.4.2.2
The floor area of the mezzanines shall be included in the area of the respective main floor.
#### 2.4.2.3
Floor area calculation shall be divided in to two: (a) All Floor areas at and above the formation level which shall be generally included in the FAR calculation. (b) Floor areas below the formation level shall generally be excluded in FAR calculation provided the Occupancy classifications remain within Utility or Private Garages.
**Table 3.2.2: Fire Resistance Ratings in Hours of Exterior Walls for Various Occupancy Groups**
| **Fire Separation Distance** | **Occupancy A1, A2, K2, M2** | **Occupancy A3, A4, A5, B, C, D, E1, F1, F2, G1, I** | **Occupancy E2, F3, F4, E3, G2, H1** | **Occupancy H2, J** |
| ------------------------------------- | ---------------------------- | ---------------------------------------------------- | ------------------------------------ | ------------------- |
| Up to 1.5 m | 1 | 2 | 3 | 4 |
| Greater than 1.5
m and up to 3 m | N | 1 | 2 | 3 |
| Greater than 3 m
and up to 4.5 m | N | N | 1 | 2 |
| Greater than 4.5
m and up to 9 m | N | N | N | 1 |
| Greater than 9 m | N | N | N | N |
N = No requirements
**Table 3.2.3: Requirements for Opening Protection Assembly Based on Fire Resistance Rating of Exterior Walls**
| **Fire Resistance Ratings of Exterior Walls (in hours)** | **Fire Resistance Ratings for Opening Assembly (in hours)** |
| -------------------------------------------------------- | ----------------------------------------------------------- |
| 4 | Not permitted |
| 3 | 3.0 |
| 2 | 1.5 |
| 1 | 0.5 |
| N | No requirements |
### **2.4.3 Permitted Types of Construction**
#### 2.4.3.1
The types of construction for any occupancy shall conform to the specifications set in Table 3.2.4.
#### 2.4.3.2
Common walls in semi-detached or row type development shall not have any unprotected openings and shall be Type I-A construction and all such wall shall comply with requirements of Party wall or Fire wall or Separation wall.
#### 2.4.3.3
Ground floor or basement of a building used for car parking and utilities within the barriers by at least three hour fire resistive construction shall be considered as non-separated occupancy provided the building accommodates one or more of the following occupancies:
* (i) A3, A5
* (ii) E1, F1, F2
(iii) I2, I3, I4
#### 2.4.3.4
Entry lobbies, mechanical and electrical rooms and other similar uses incidental to the operation of the building may be provided in the car parking floors provided that the total area of such uses remains within ⅓ (one third) of the parking floor area.
**Table 3.2.4: Permitted Types of Construction and Fire Zones for Various Occupancy Groups**
| Occupancy | Permitted Types of Construction | Fire Zones |
| --------------------------------------------------------- | ------------------------------- | ---------- |
| A, B, C, D, E1, F1, F2, I, K1, K2, M2, E2, E3, F3, K3, M1 | Group I and Group II\* | 1 |
| G, H | Group I or Group II\* | 2 |
| J | Group I | 3 |
\*Fire resistance rating of a building shall be credited in case of the mixed type of construction on the basis of lower rated construction elements among the same group or same type used thereof.
### **2.4.4 General Provision for High-Rise Buildings**
For the purpose of this Code, a building of any class of Occupancy will be considered as high-rise when it has floors used for human occupancy located more than 33 m from ground level or the lowest level of fire department vehicle access. The provisions of Sec 2.9.6 shall be applicable to all such buildings.
#### 2.4.4.1 Maintenance and inspection
All fire protection systems shall be maintained and inspected on a regular basis to keep them in operative condition. The maintenance inspection shall be performed quarterly.
All plumbing installations shall be maintained and inspected periodically to keep them in operative conditions.
#### 2.4.4.2 Type of construction
All high-rise buildings shall be of Type I-A or I-B construction.
#### 2.4.4.3 Fire detection, alarm, evacuation and extinguishment system
All high-rise buildings shall conform to regulations set forth in Part 4 of this Code
### **2.4.5 Helipads**
#### 2.4.5.1 General
Helipads on the roof top of a building or other locations shall be constructed in accordance with this Section.
#### 2.4.5.2 Size
The minimum dimension of the landing area for helicopters weighing less than 1600 kg shall be 6 m × 6 m. There shall be an average clearance of 4 m surrounding and at the level of the landing area which shall not be less than 2 m at any point.
#### 2.4.5.3 Construction
Helicopter landing areas and supports shall be constructed with non-combustible material.
#### 2.4.5.4 Aviation approval
Before helipads start operating, formal approval shall be obtained from the civil aviation authority.
### **2.4.6 Universal Accessibility**
#### 2.4.6.1
All Building (except Occupancies G, H, M and J) shall have universal accessibility as per provisions of this Code.
#### 2.4.6.2
Buildings have universal accessibility shall have accessible egress system.
## **2.5 Requirements For Occupancy A- Residential Buildings**
Buildings shall be classified as Occupancy A in accordance with Sec 2.1.5.
### **2.5.1 Construction, Height and Allowable Area**
#### 2.5.1.1
Buildings or parts thereof classified as Occupancy A shall be limited to the type of construction set forth in Table 3.2.4 and shall not exceed in area or height as specified in Sections 1.8 and 2.4.2 of this Part.
#### 2.5.1.2
Walls and floors separating dwelling units in the same building shall not be less than Type I-D construction.
#### 2.5.1.3
Storage or laundry rooms in Occupancy A2, A3, A4 or A5 that are used in common by the occupants shall be at least Type I-D construction.
#### 2.5.1.4
When a basement or a ground floor of a building of Occupancy A3 or A5 is used for parking or storage of private cars of the occupants, the parking floor shall be of at least Type I-B construction.
#### 2.5.1.5
When the basement or ground floor of a building of Occupancy A is used wholly or partly for generator or electrical substation, the walls and floors surrounding such use shall be of at least Type I-B construction.
### **2.5.2 Location on Property**
Buildings of Occupancy A shall comply with the requirements for location on property and fire resistive exterior walls and openings as specified in this Code.
### **2.5.3 Access and Exit Facilities and Egress System**
#### 2.5.3.1
Facilities for access and exit and egress or escape shall comply with the provisions set forth in this Code.
#### 2.5.3.2
Every sleeping room in ground, first and second floors shall have at least one operable window or door for emergency escape which shall open directly into the exterior or an interior courtyard. The units shall be operable from the inside without the use of any tool to provide a minimum clear opening of 500 mm width by 600 mm height with a maximum sill height of 1 m above the floor.
### **2.5.4 Lighting and Ventilation**
All buildings or part of a building classified as Occupancy A shall conform to the provisions of Part 3, and Chapters 1 and 3 of Part 8.
### **2.5.5 Sanitation**
Sanitation facilities provided in all Occupancy A buildings shall conform to this Part and Chapter 7 Part 8.
### **2.5.6 Minimum Dimension of Habitable and Non-habitable Rooms**
The minimum dimensions of habitable and non-habitable rooms are specified in Sec 1.12.2 Chapter 1 Part 3.
### **2.5.7 Fire detection, Alarm, Evacuation and Extinguishment**
All buildings shall conform to regulations set forth in Part 4 of this Code.
### **2.5.8 Shaft and Exit Enclosure**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with Part 4 of this Code.
## **2.6 Requirements For Occupancy B - Educational Buildings**
Buildings shall be classified as Occupancy B in accordance with Sec 2.1.6.
### **2.6.1 Construction, Height and Allowable Area**
Buildings or parts of buildings classified as Occupancy B shall be limited to type of construction set forth in Table 3.2.4 and comply with the provisions of Sections 1.8 and 2.4.2 of this Part to meet the requirements of height and area limitations.
#### 2.6.1.1
Rooms or groups of rooms sharing a common space where flammable liquids, combustible dust or hazardous materials are used, stored, developed or handled in an amount exceeding that specified in Sec 2.14.3 shall be classified as Occupancy J. Such rooms or groups of rooms shall comply with the requirements of fire protection as specified in Part 4, Chapters 4 and 5.
#### 2.6.1.2
Rooms or groups of rooms, sharing a common space or having separate spaces, served by a common corridor or passage with less than 20 percent outdoor opening of wall in a building of height 11 m or less, or three storeys or less, need not be provided with smoke detectors and standpipe or sprinkler system for fire protection provided it conforms with the access and exit requirements specified in Part 3, Chapter 1, Sec 1.6 and Part 4, Chapters 4 and 5.
#### 2.6.1.3
Buildings of Occupancy B situated outside the jurisdiction of any municipality shall have a construction of at least two hours fire resistance.
### **2.6.2 Location on Property**
Buildings of Occupancy B shall comply with the requirements for location on property and fire resistive exterior walls and openings as specified in Sec 2.4.1.
### **2.6.3 Access and Exit Facilities and Egress System**
Facilities for access and exit and Egress system shall comply with the provisions set forth in Sec 1.6, Chapter 1 Part 3 and Chapter 3 Part 4.
### **2.6.4 Lighting, Ventilation and Sanitation**
Lighting, ventilation and sanitation facilities provided in Occupancy Group B buildings shall conform to Sec 1.16, Chapter 1 Part 3 and Chapters 1 and 3 Part 8.
### **2.6.5 Minimum Dimensions of Class Rooms, Common Toilets and Staircases**
The dimension of a class room shall be not less than 4 m on any side and shall have an area of not less than 0.75m² per student. Other provisions for minimum dimensions shall comply with the requirements set forth in Sec 1.8 of Chapter 1 Part 3.
### **2.6.6 Shaft and Exit Enclosure**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with Chapter 3 Part 4.
### **2.6.7 Fire Detection, Alarm, Evacuation and Extinguishment System**
All buildings shall conform to regulations set forth in Part 4 of this Code.
## **2.7 Requirements For Occupancy C- Institutional Buildings**
Buildings shall be classified as Occupancy C in accordance with Sec 2.1.7.
### **2.7.1 Construction, Height and Allowable Area**
The buildings or parts thereof classified as Occupancy C shall be limited to the type of construction set forth in Table 3.2.4 and shall comply with the provisions of Sec 1.8 Chapter 1 Part 3 and Sec 2.4.2 to meet the requirements of height and area limitations.
### **2.7.2 Location on Property**
Buildings of Occupancy C shall comply with the requirements for location on property and fire resistive exterior walls and openings as specified in Sec 2.4.1.
### **2.7.3 Access and Exit Facilities and Egress System**
Facilities for access and exit and egress system shall comply with the provisions set forth in Sec 1.6, Chapter 1 Part 3 and Chapter 3 Part 4.
### **2.7.4 Lighting, Ventilation and Sanitation**
All buildings or part of a building classified as Occupancy C shall conform to the provisions of Sec 1.16, Chapter 1 Part 3 and Chapters 1 and 3, Part 8.
### **2.7.5 Shaft and Enclosure**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with Chapter 3, Part 4.
### **2.7.6 Fire Detection, Alarm, Evacuation and Extinguishment System**
All buildings shall conform to regulations set forth in Part 4 of this Code.
## **2.8 Requirements For Occupancy D–Health Care Facilities**
Buildings shall be classified as Occupancy D in accordance with Sec 2.1.8.
### **2.8.1 Construction, Height and Allowable Area**
The buildings or parts thereof classified as Occupancy D shall be limited to the type of construction set forth in Table 3.2.4 and shall comply with the provisions of Sec 1.8 Chapter 1 Part 3 and Sec 2.4.2 to meet the requirements of height and area limitations.
### **2.8.2 Location on Property**
Buildings of Occupancy D shall comply with the requirements for location on property and fire resistive exterior walls and openings as specified in Sec 2.4.1.
### **2.8.3 Access and Exit Facilities and Egress System**
Facilities for access and exit and egress system shall comply with the provisions set forth in Sec 1.6 Chapter 1, Part 3 and Chapter 3 of Part 4.
### **2.8.4 Lighting, Ventilation and Sanitation**
All buildings or part of a building classified as Occupancy D shall conform to the provisions of Sec 1.16 Chapter 1 Part 3, Chapters 1 and 3 of Part 8.
### **2.8.5 Shaft and Enclosure**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with Chapter 3 of Part 4.
### **2.8.6 Fire Detection, Alarm, Evacuation and Extinguishment System**
All buildings shall conform to regulations set forth in Part 4 of this Code.
## **2.9 Requirements For Occupancy E–Business**
Buildings shall be classified as Occupancy E in accordance with Sec 2.1.9.
### **2.9.1 Construction, Height and Allowable Area**
The buildings or parts thereof classified as Occupancy E shall be limited to the type of construction set forth in Table 3.2.4 and shall comply with the provisions of Sec 1.8 Chapter 1 Part 3 and Sec 2.4.2 to meet the requirements of height and area limitations.
### **2.9.2 Location on Property**
Buildings of Occupancy E shall comply with the requirements for location on property and fire resistive exterior walls and openings as specified in Sec 2.4.1.
### **2.9.3 Access and Exit Facilities and Egress System**
Facilities for access and exit and egress system shall comply with the provisions set forth in Sec 1.6 Chapter 1 Part 3, Chapter 3 of Part 4.
### **2.9.4 Lighting, Ventilation and Sanitation**
All buildings or part of a building classified as Occupancy E shall conform to the provisions of Sec 1.16 Chapter 1 Part 3, Chapters 1 and 3 of Part 8.
### **2.9.5 Shaft and Enclosure**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with Chapter 3 of Part 4.
### **2.9.6 Fire Detection, Alarm, Evacuation and Extinguishment System**
All buildings shall conform to regulations set forth in Part 4 of this Code.
## **2.10 Requirements For Occupancy F–Mercantile Buildings**
Buildings shall be classified as Occupancy F in accordance with Sec 2.1.10.
### **2.10.1 Construction, Height and Allowable Area**
The buildings or parts thereof classified as Occupancy F shall be limited to the type of construction set forth in Table 3.2.4 and shall comply with the provisions of Sec 1.8, Chapter 1 of Part 3 and Sec 2.4.2 to meet the requirements and limitations of height and area.
### **2.10.2 Location on Property**
Buildings of Occupancy F shall comply with the requirements for location on property and fire resistive exterior walls and openings as specified in Sec 2.4.1.
### **2.10.3 Access and Exit Facilities and Emergency Escapes**
Facilities for access and exit and emergency escape shall comply with the provisions set forth in Sec 1.6 Chapter 1 Part 3 and Chapter 3 Part 4.
### **2.10.4 Lighting, Ventilation and Sanitation**
All buildings or part of a building classified as Occupancy F shall conform to the provisions of Sec 1.16 Chapter 1 Part 3, Chapters 1 and 3, Part 8.
### **2.10.5 Shaft and Enclosure**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with Chapter 3, Part 4.
### **2.10.6 Fire Detection, Alarm, Evacuation and Extinguishment System**
All buildings shall conform to regulations set forth in Part 4 of this Code.
### **2.10.7 Special Hazards**
Installations which are discharging exhaust, heating apparatus, boiler and central heating/air-conditioning plant shall conform to the provisions of this Code as specified in this Code.
## **2.11 Requirements For Occupancy G–Industrial Buildings**
Buildings shall be classified as Occupancy G in accordance with Sec 2.1.11. A nonexhaustive and indicative list of low hazard and moderate hazard industrial uses are listed in A to Z list. Storage and use of hazardous materials shall not exceed the exempt amount specified in Sec 2.14.3.
### **2.11.1 Construction, Height and Allowable Area**
The buildings or parts thereof classified as Occupancy G shall be limited to the type of construction set forth in Table 3.2.4 and shall comply with the provisions of Sec 1.8 of Chapter 1, Part 3 and Sec 2.4.2 to meet the requirements and limitations of height and floor area.
The ceiling height of the production area, shall confirm to the minimum volume required per workers as specified by the Bangladesh Labor Act, 2006 and other laws of the land. In any case the ceiling height and the head room clearance of a production floor shall not be less than 3.3 meter and 2.286 meter respectively.
### **2.11.2 Location on Property**
Buildings of Occupancy G shall comply with the requirements for location on property and fire resistive exterior walls and openings as specified in Sec 2.4.1.
### **2.11.3 Access and Exit Facilities and Egress System**
Facilities for access and exit and emergency escape shall comply with the provisions set forth in Sec 1.6 Chapter 1, Part 3 and Chapter 3, Part 4.
### **2.11.4 Lighting, Ventilation and Sanitation**
All buildings or part of a building classified as Occupancy G shall conform to the provisions of Sec 1.16 Chapter 1, Part 3 and Chapters 1 and 3, Part 8. Industrial buildings having roof opening for day lighting and natural ventilation shall comply with the following requirements:
* (a) The aggregate opening in roof and external windows shall not be less than 10 Percent of the floor area.
* (b) For natural ventilation by means of exterior window openings, the operable window area shall not be less than 5 Percent of the total floor area.
Exception:
Industrial buildings wherein artificial lighting and mechanically operated ventilation systems of approved quality are installed, need not be provided with natural ventilation or natural lighting.
### **2.11.5 Shaft and Enclosure**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with Chapter 3, Part 4.
### **2.11.6 Fire Detection, Alarm, Evacuation and Extinguishment System**
All buildings shall conform to regulations set forth in Part 4 of this Code.
### **2.11.7 Special Hazards**
Chimneys, vents and ventilation ducts shall be constructed with noncombustible materials. Every bailer, central heating plants, electrical rooms, or hot water supply boiler shall be separated from the rest of the occupancy or use by not less than two hour fire resistive construction.
## **2.12 Requirements For Occupancy H–Storage Buildings**
Buildings shall be classified as Occupancy H in accordance with Sec 2.1.12.
### **2.12.1 Construction, Height and Allowable Area**
The buildings or parts thereof classified as Occupancy H shall be limited to the type of construction set forth in Table 3.2.4 and shall comply with the provisions of Sec 1.8 of Chapter 1, Part 3 and Sec 2.4.2 to meet the requirements of height and area limitations.
### **2.12.2 Location on Property**
The location on property for Occupancy H shall conform to Sec 2.4.1.
### **2.12.3 Access and Exit Facilities and Egress System**
Facilities for access and exit and egress system shall comply with the provisions set forth in Sec 1.6 of Chapter 1, Part 3 and Chapter 3, Part 4.
### **2.12.4 Lighting, Ventilation and Sanitation**
All buildings or part of a building classified as Occupancy H shall conform to the provisions of Sec 1.16 of Chapter 1 Part 3, Chapters 1 and 3, Part 8.
#### 2.12.4.1 Special provision
The provisions of Sec 1.16, does not apply to non-habitable spaces of H1 and H2 occupancies unless otherwise required by this Code. Ventilators of size not less than 0.25 m² shall be provided where suitable 0.30 m above the floor level for floor level ventilators and 0.30 m below the roof level for roof level ventilators. There shall be one floor level ventilator and one roof level ventilator for every 0.25 m² of the floor area. Mechanized ventilation system of approved quality shall be installed where required.
#### 2.12.4.2
Though inhabitable, the minimum air quality of such indoor spaces shall be maintained in a way that it does not pose any health hazard to the occasional users of that space.
### **2.12.5 Shaft and Enclosure**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with Chapter 3, Part 4.
### **2.12.6 Fire Detection, Alarm, Evacuation and Extinguishment System**
All buildings shall conform to regulations set forth in Part 4 of this Code.
### **2.12.7 Special Hazards**
The storage of hazardous materials shall not exceed the exempt amount as specified in Table 3.2.5. The storage of moderate and low hazardous materials shall be separated at least by a two hour fire resistive construction.
## **2.13 Requirements For Occupancy I–Assembly Buildings**
Buildings shall be classified as Occupancy I in accordance with Sec 2.1.13.
### **2.13.1 Construction, Height and Allowable Area**
The buildings or parts thereof classified as Occupancy I shall be limited to the type of construction set forth in Table 3.2.4 and shall comply with the provisions of Sec 1.8 Chapter 1 Part 3 and Sec 2.4.2 to meet the requirements and limitations of height and area.
### **2.13.2 Location on Property**
Buildings of Occupancy I shall comply with the requirements for location on property and fire resistive exterior walls and openings as specified in Sec 2.4.1.
### **2.13.3 Access and Exit Facilities and Egress System**
Facilities for access and exit and Egress system shall comply with the provisions set forth in Sec 1.6 Chapter 1 of Part 3 and Chapter 3 of Part 4 and universally accessibility as per provisions of this Code.
### **2.13.4 Lighting, Ventilation and Sanitation**
All buildings or part of a building classified as Occupancy I shall conform to the provisions of Sec 1.16 Chapter 1 Part 3, Part 3 and Chapters 1 and 3, Part 8.
### **2.13.5 Shaft and Enclosure**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with Chapter 3, Part 4.
### **2.13.6 Fire Detection, Alarm, Evacuation and Extinguishment System**
All buildings shall conform to regulations set forth in Part 4 of this Code.
The specification of this Section shall apply to all parts of buildings and structures that contain stages or platforms and other similar appurtenances as herein defined.
* (a) Stages: A stage is a three side enclosed or partially enclosed portion of a building which is designed or used for presentation of plays or lectures or other entertainment. A stage shall be further classified as legitimate stage, regular stage and thrust stage.
* (b) Stage, Legitimate: A stage wherein curtains, drops, leg drops, scenery, lighting devices or other stage effects are adjustable horizontally or vertically or suspended overhead.
* (c) Stage, Regular: A stage wherein curtains, fixed drops, valances, scenery and other stage effects are suspended and are not adjustable or retractable.
* (d) Stage, Thrust: A stage or platform extended beyond the proscenium line and into the audience.
#### 2.13.6.1 Legitimate Stage
Legitimate stage shall be constructed as specified in Part 4, specifying the type of construction but shall not be less than construction Type I-C. The position of the legitimate stage extending beyond the proscenium opening line shall be permitted to be constructed with two hour fire-resistive materials. The floor of the stage may be constructed with one hour fire rating materials. Thickness of a wooden floor shall not be less than 50 mm.
#### 2.13.6.2 Regular and Thrust Stages
Regular stages and thrust stages shall be constructed by not less than two hour fire resistive materials. Wooden floor when required in a stage shall not be less than 50 mm in thickness with one hour fire resistive rating.
#### 2.13.6.3 Trap doors
All trap doors and any other opening in stage floors shall be equipped with tight fitting solid wood trap doors with thickness not less than 50 mm.
#### 2.13.6.4 Stage rigging loft
The grid iron frame in the loft, housing lighting and audio equipment, all the machinery for flying scenery and fly galleries, along with their installations, shall be constructed of approved noncombustible materials.
#### 2.13.6.5 Foot lights and stage electrical equipment
Foot lights and border lights shall be installed in a protective cover constructed of noncombustible materials.
#### 2.13.6.6 Trim, finish and decorative hangings
All materials used in moulding and decoration around the proscenium shall be of approved noncombustible materials.
#### 2.13.6.7 Proscenium curtain
The proscenium curtain shall be of approved fire retardant material and shall protect against passage of flame and smoke for at least 30 minutes.
### **2.13.7 Motion Picture Projection Rooms**
#### 2.13.7.1
Every projection room shall be constructed in conformity with the construction requirements for the type of the building in which the projection room is located. The wall opening required for projection need not have a fire protection assembly but shall be closed with glass or other approved materials.
#### 2.13.7.2
The floor area of a projection room shall not be less than 8 m² for a single machine. The working space between the machines when more than one machine is used shall not be less than 0.75 m.
#### 2.13.7.3
The height of the projection room shall have a minimum clear space of 2.5 m.
### **2.13.8 Sports Facilities**
#### 2.13.8.1 Vomiters, aisles and exits of seating galleries
Tunnels, aisles and exits of galleries shall be constructed conforming to the following requirements.
* (a) There shall be a minimum of two exits remotely located from each other immediately to the outside for each balcony or tier. There shall be at least three exits when seating capacity exceeds 1000 persons and four exits when it exceeds 4000 persons. For every additional 1000 persons the exit shall be designed to accommodate provision (f) given below.
* (b) There shall be at least 0.6 m2 of space per person in the gallery. Minimum width considered for a seat in the gallery shall be 0.45 m.
* (c) There shall be a maximum of 33 seats on each side of any aisle. Minimum width of the main aisles and the secondary aisles shall be 1.0 m and 0.7 m respectively.
* (d) Entrance and exits shall be protected by safety railings.
* (e) Back to back space between two rows of seats shall not be less than 0.80 m.
* (f) The evacuation time in the galleries shall not be more than 10 minutes.
* (g) All tunnels, aisles and exits shall conform to safety guidelines for means of escape set forth in Part 4.
* (h) One percent of the total seat capacity shall have provisions for accommodation with universal accessibility at the approach or exit level.
#### 2.13.8.2 Swimming pools
Any swimming pool used or constructed for exclusive use by Occupancy A1 and is available only to the occupants and private guests shall be classified as a private swimming pool. Any swimming pool other than private swimming pool shall be classified as a public swimming pool. Swimming pools shall be constructed in conformity with the following requirements.
* (a) There shall be at least 1.5 m space between any sides of a swimming pool and a rear or side property line. For street property lines, this distance shall be at least 2.0 m.
* (b) Swimming pools shall be provided with overflow provision to remove scum and other materials from the surface of the water. When water skimmers are used for private pools there shall be one skimming device for each 50 m2 of surface area or fraction thereof.
* (c) The overflow gutters shall not be less than 75 mm deep and shall be pitched to slope of one unit vertical to 50 units horizontal (1:50) toward drains.
* (d) Public swimming pools shall be so designed that the pool water turnover is at least once every 8 hours.
* (e) Private swimming pools shall be designed so that there is a pool water turnover at least once every 18 hours.
* (f) Public swimming pools shall be equipped with filters, the capacity of which shall be controlled to filter 140 liters per minute per m2 of surface area. Private swimming pool filters shall not filter more than 230 liters per minute per m2 of the surface area.
* (g) The pH value of the pool water shall be between 7.0 and 7.5.
* (h) All recirculation systems shall be equipped with an approved hair and lint strainer installed in the system ahead of the pump.
* (i) All swimming pool and equipment shall be designed to be emptied completely of water and the discharged water shall be disposed in an approved manner and shall not create problems in the neighboring property.
* (j) Pumps, filters and other mechanical and electrical equipment shall be placed in enclosed spaces and shall not be accessible to the bathers.
* (k) Used water from the pool when being discarded shall be reused as grey water for the building and its premises as per provision of Appendix G.
### **2.13.9 Amusement Building Fire Protection System**
The fire protection system shall be as per provisions of this Code.
## **2.14 Requirements For Occupancy J–Hazardous Buildings**
Buildings shall be classified as Occupancy J in accordance with Sec 2.1.14.
### **2.14.1 General**
The plans for buildings and structures accommodating Occupancy J shall clearly indicate the type and intended use of materials and its processing or handling methods so as to reflect the nature of use of each portion of such buildings.
#### 2.14.1.1 Occupancy J1
Any building or portion thereof containing any of the following items more than exempted quantity shall be classified as Occupancy J1.
* (a) Combustible dusts and any similar solid material sufficiently comminuted for suspension in still air which, when so suspended, is capable of self-sustained combustion.
* (b) Combustible liquids - Any liquid having a flash point at or above 40°C shall be known as class II and class III liquids. Combustible liquids shall be classified as follows:
* (i) Liquids having flash point at or above 40°C and below 60°C.
* (ii) Liquids having flash points at or above 60°C and below 95°C.
* (c) Cryogenic liquids (flammable or oxidizing): Any liquid that has a boiling point below -130°C.
* (d) Flammable Gases: Any gas when mixed with air in a proportion of 13% (by volume) forms a flammable mixture under atmospheric temperature and pressure.
* (e) Flammable Liquids: Any liquid that has a flash point below 40°C and has a net vapour pressure exceeding 275 kPa at 40°C. Flammable liquids shall be known as Class I liquid and shall be further classified as follows:
* (i) Liquids having flash point below 25°C and having a boiling point below 40°C.
* (ii) Liquids having flash point below 25°C and having a boiling point at or above 40°C.
* (iii) Liquids having flash points at or above 25°C and below 40°C.
* (f) Oxidizers class 3: As determined in accordance with NFPA 43A.
* (g) Oxidizing gases: As determined in accordance with NFPA 43C.
* (h) Pyrophoric liquids, solids and gases that will ignite spontaneously in air at a temperature of 55°C or below.
* (i) Unstable (reactive) materials class 3, non-detonable as determined in accordance with NFPA 704.
* (j) Combustible fibers: Includes readily ignitable fibers like cotton, sisal, jute hemp, tow, cocoa fiber, oakum, baled waste, baled waste paper, kapok, hay, straw, excelsior, Spanish moss and other similar materials.
* (k) Flammable solid: Any solid including blasting agent or explosive that is liable to cause fire through absorption of moisture, spontaneous chemical change or retained heat from manufacturing or processing, or which when ignited burns so vigorously and persistently as to create a serious hazard.
* (l) Organic peroxides, Class II and Class III as determined in accordance with NFPA 43B.
* (m) Oxidizers Class I and Class II as determined in accordance with NFPA 43A.
* (n) The bulk storage of unstable (reactive) materials Class 1 and Class 2 as determined in accordance with NFPA 704, water reactive materials, Class 2 and Class 3 which react with water to release a gas that is either flammable or present a health hazard as determined in accordance with NFPA 704.
#### 2.14.1.2 Occupancy J2
Any building or portion thereof containing the following shall be classified as
Occupancy J2:
* (a) Corrosives: Any substance that causes visible destruction of or irreversible alteration in living tissues by chemical action at the site of contact.
* (b) Highly toxic materials: The materials falling in this category are as follows:
* (i) Oral Toxicity: A chemical that has a median lethal dose of 50 mg or less per kg of body weight when administered orally to albino rats weighing between 200 and 300 gm each.
* (ii) Toxicity of Inhalation: A chemical that has a median lethal concentration in air of 200 ppm or less by volume of gas or vapors, or 2 mg per liter or less of mist, fume or dust, when administered by continuous inhalation for 1 hour (or less if death occurs within 1 hour) to albino rats weighing between 200 and 300 grams each.
* (iii) Toxicity by Skin Absorption : A chemical that has median lethal dose of 200 mg or less per kg of body weight when administered by continuous contact for 24 hours (or less if death occurs within 24 hours) with the bare skin of albino rabbits weighing between 2 and 3 kg each.
* (iv) Irritants: Any noncorrosive chemical or substance which causes a reversible inflammatory effect on living tissues by chemical action at the site of contact.
* (v) Radioactive Material: Any material or combination of materials that spontaneously emit ionizing radiation.
* (vi) Sensitizers: A chemical or substance that causes a substantial proportion of exposed people or animals to develop an allergic reaction in normal tissue after repeated exposure.
* (c) The Occupancy J2 shall also include among others the followings:
* (i) Dry cleaning establishments using flammable solvents.
* (ii) Explosive manufacturing.
* (iii) Paint or solvent manufacturing (flammable base).
* (iv) Pyrexin plastic manufacturing.
* (v) Sodium nitrate or ammonium nitrate.
* (vi) Storage of combustible film.
#### 2.14.1.3 Occupancy J3
Any building or portion thereof which is used for storage, handling, processing or manufacture of materials and products that use biological processes and in which the risk of harmful biological threat to the occupants exist, shall comply with the guidelines specified by the Department of Health.
#### 2.14.1.4 Occupancy J4
Any building or portion thereof which is used for storage, handling, processing or manufacture of materials and products that use nuclear and radioactive processes and in which the risk of radioactive contamination exists, shall comply with the guidelines specified by Bangladesh Atomic Energy Commission.
### **2.14.2 Special Provisions**
#### 2.14.2.1
The following shall not be included in Occupancy J but shall be classified in the occupancy group which they most nearly resemble and such classification shall be approved by the Authority:
* (a) All buildings and structures and parts thereof which contain less than the exempt quantities as specified in Table 3.2.5, when such buildings comply with the fire protection provisions of this Code.
* (b) Rooms containing flammable liquid in lightly closed containers of 4 litre capacity or less for retail sales or private use on the premises and in quantities not exceeding 820 litres/m² of room area.
* (c) Retail paint sales rooms with quantities not exceeding 820 litres/m² of room area.
* (d) Closed systems housing flammable or combustible liquids or gases used for the operation of machinery or equipment.
* (e) Cleaning establishments.
* (f) Liquor stores and distributors without bulk storage.
* (g) Tire storage containing less than 10,000 vehicle tires.
* (h) The storage or use of materials for agricultural purposes for use on the premises.
* (i) Pyrophoric solids or liquids not exceeding 3 m3 in storage cabinet located in a building that is equipped throughout with an automatic sprinkler system provided in accordance with the fire protection provisions of this Code.
* (j) Pyrophoric solids or liquids not exceeding 3 kg in storage cabinet located in a building that is provided with an automatic sprinkler system installed in accordance with the fire protection provisions in accordance to Part 4 of this Code.
* (k) Class 2 water reactive materials not exceeding 100 kg in an approved storage cabinet located in a building that is provided with automatic sprinkler installed in accordance with the fire protection provisions in accordance to Part 4 of this Code.
### **2.14.3 Construction, Height and Allowable Area**
#### 2.14.3.1
The buildings or parts thereof classified as Occupancy J shall be limited to the type of construction set forth in Table 3.2.4 and shall comply with the provisions of Sec 1.8 of Chapter 1, Part 3 and Sec 2.4.2 of this Chapter to meet the requirements of height and area limitations.
#### 2.14.3.2
Floors: The floors and spaces containing hazardous materials and in areas where motor vehicles, boats, helicopters or airplanes are stored, repaired or operated shall be of noncombustible, liquid-tight construction.
Exception: In floors and areas where no repair works are carried out may be surfaced or waterproofed with asphaltic paving materials.
#### 2.14.3.3
Spill Control: The floors containing hazardous repair or other works shall be recessed a minimum of 100 mm so as to prevent flow of liquids to adjoining areas.
#### 2.14.3.4
Drainage: The buildings and areas shall be provided with approved drainage system to direct the flow of liquids to an approved location or room or area designed to provide secondary containment of the hazardous materials and fire protection water.
**Table 3.2.5(a): Exempted Amount of Hazardous Materials in Terms of Physical Hazard in a Control Area**
| Sl. No. | Material | Class/State | Storage Limit | Use — Closed Systems | Use — Open Systems |
| ------- | --------------------------------- | ------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------- |
| 1 | Flammable liquids | Class I-A
Class I-B and Class I-C | 115 liters \*
454 liters \* | 115 liters \*
454 liters \* | 38 liters
115 liters |
| 2 | Combustible liquids | Class-II
Class-III-A
Class-III-B | 454 liters\*
1249 liters\*
49962 liters\* | 454 liters\*
1249 liters\*
49962 liters\* | 114 liters
320 liters
12490 liters |
| 3 | Combination of flammable liquids | Class I-A
Class I-B
Class I-C | 454 liters\* | 454 liters\* | 113 liters\* |
| 4 | Flammable gases | Gaseous
Liquefied | 28 m3 at NTP (Natural Temperature and Pressure)
113 liters | 28 m3 at NTP (Natural Temperature and Pressure)
113 liters | Not applicable
Not applicable |
| 5 | Liquefied flammable | Class I-A
Class I-B and Class I-C | 113 liters
454 liters | 113 liters
454 liters | 38 liters
113 liters |
| 6 | Combustible fibres | Loose
Baled | 2.832 m3
28.32 m3 | 2.832 m3
28.32 m3 | 0.57 m3
5.7 m3 |
| 7 | Flammable solids | Pigs, ingots, heavy castings
Light castings, light metallic products
Scraps, shavings, powders, dusts | 454 kg
57 kg
0.454 kg | 454 kg
57 kg
0.454 kg | 454 kg
57 kg
0.454 kg |
| 8 | Unstable (reactive) detonable | Class 4
Class 3 | 0.454kg or 0.28m3(NTP)
0.454kg or 0.28m3(NTP) | 0.113 kg or 0.057m3(NTP)
0.113 kg or 0.057m3(NTP) | 0.454kg or 0.28m3(NTP)
0.454kg or 0.28m3(NTP) |
| 9 | Unstable (reactive) detonable | Class 4
Class 3
Class 2
Class 1 | 0.454kg or 0.28m3(NTP)
2.27 kg or 1.42m3(NTP)
22.7kg or 70.8 m3(NTP)
Not limited or 21.24m3(NTP) | 0.113 kg or 0.057m3(NTP)
0.454kg or 0.2832m3(NTP)
22.7kg or 70.8m3(NTP)
Not limited | 0.454kg or 0.28m3(NTP)
0.454kg
4.54 kg
Not limited |
| 10 | Water-reactive detonable | 3
2 | 0.454 kg
0.454 kg | 11.25 kg
11.25 kg | 11.25 kg
11.25 kg |
| 11 | Water-reactive non-detonable | 3
2
1 | 2.27 kg
22.7 kg
Not limited | 2.27 kg
22.7 kg
Not limited | 0.454 kg
4.54 kg
Not limited |
| 12 | Oxidizing Materials | Class 4
Class 3
Class 2
Class 1 | 0.454 kg
4.54 kg
113 kg
1816 kg | 0.1135kg
0.227kg
113 kg
1816 kg | 0.1135kg
0.227kg
113 kg
1816 kg |
| 13 | Oxidizing Gas | Gaseous
Liquefied | 42.48 m3(NTP)
56.78 liters | 42.48 m3(NTP)
56.78 liters | Not applicable
Not applicable |
| 14 | Pyrophoric Material detonable | Not applicable | 0.454 kg or 0.056 m3(NTP) | 0.056 m3(NTP) | 0 |
| 15 | Pyrophoric Material non-detonable | Not applicable | 1.8 kg. or 1.4 m3(NTP) | 0.28m3(NTP) | 0 |
| 16 | Explosives\*\* | Division 1.1
Division 1.2
Division 1.3
Division 1.4
Division 1.4G
Division 1.5
Division 1.6 | 0.454 kg
0.454 kg
2.27 kg
22.7 kg
56.75 kg
0.454 kg
0.454 kg | 0.1135 kg
0.1135 kg
0.454 kg
22.7 kg
Not applicable
0.1135 kg
Not applicable | 0.1135 kg
0.1135 kg
0.454 kg
Not applicable
Not applicable
0.1135 kg
Not applicable |
\* The maximum quantities may be increased by 100 percent in areas not accessible to the public in buildings provided with automatic sprinkler system.
\*\* see: Explosive control act.
**Table 3.2.5(b): Exempted Amounts of Hazardous Materials in Terms Health Hazard in a Control Area**
| Material | Class/State | Single Storage | Closed Systems | Open Systems |
| ------------ | -------------- | ---------------------------------------------- | -------------------------------------------- | ------------------- |
| Corrosive | Not applicable | 2270 kg or 1892 liters or 23 m3 NTP | 227kg or 1892 liters or 23 m3 NTP | 454kg or 379 liters |
| Highly toxic | Not applicable | 4.54 kg or 0.57 m3 NTP | 4.54 kg or 0.57 m3 NTP | 1.362 kg |
| Toxic | Not applicable | 227 kg or 23 m3 NTP | 227 kg | 56.75 kg |
**Table 3.2.5(c): Location and Number of Control Areas**
| Grade Level | Floor Level1 | Number of Control Areas per Floor2 | Walls | Floors | Floor Supporting Members |
| ----------- | ----------------------- | --------------------------------------------- | ----------- | ----------- | ------------------------ |
| Above | Higher than 9 | 5 | 1 | 2 | 2 |
| Above | 7-9 | 5 | 2 | 2 | 2 |
| Above | 6 | 12.5 | 2 | 2 | 2 |
| Above | 5 | 12.5 | 2 | 2 | 2 |
| Above | 4 | 12.5 | 2 | 2 | 2 |
| Above | 3 | 50 | 2 | 1 | 2 |
| Above | 2 | 75 | 3 | 1 | 2 |
| Above | 1 | 100 | 4 | 1 | 2 |
| Below | 1 | 75 | 3 | 1 | 2 |
| Below | 2 | 50 | 2 | 1 | 2 |
| Below | Lower than 2 | Not Allowed | Not Allowed | Not Allowed | Not applicable |
The "Walls", "Floors", and "Floor Supporting Members" columns are the fire resistance rating of barriers, in hours. The maximum allowable quantity per control area is shown in Table 3.2.5.
#### 2.14.3.5
The drains shall be designed with adequate slope and section to carry the design discharge of the sprinkler system. The material used in the drains shall be suitable for drainage of the storage materials.
#### 2.14.3.6
Separate drainage system shall be designed for materials which react with each other producing undesirable results. They may be combined when they have been provided with approved means of discharge into the public sewer or natural stream or river.
#### 2.14.3.7
Containment: The outflow from the drains shall be directed to a containment system or other area that provide a secondary storage for the hazardous materials and liquids and fire protection water. The containment capacity shall be capable of containing the outflow from the drains for a period of at least one hour.
#### 2.14.3.8
The overflow from secondary containment system shall be directed to a safe location away from the building, adjoining properties and storm drain.
#### 2.14.3.9
If the secondary containment storage area is open to rainfall it shall be designed to accommodate 24 hour rainfall or a continuous rainfall of 100 mm per day.
#### 2.14.3.10
Smoke and Heat Vents: Smoke and heat vents shall be provided in areas or rooms containing hazardous materials exceeding the exempt amount of Table 3.2.5.
#### 2.14.3.11
Standby Power: Standby power shall be provided in the occupancies where Class I, II or III organic peroxides are stored.
### **2.14.4 Location on Property**
The location on property for Occupancy J shall conform to Sec 2.4.1 and Part 4.
### **2.14.5 Access and Exit Facilities and Emergency Escapes**
Facilities for access and exit and emergency escape shall comply with the provisions set forth in Sec 1.6 of Chapter 1, Part 3, and Chapter 3, Part 4.
### **2.14.6 Lighting and Ventilation**
#### 2.14.6.1
All spaces and rooms customarily occupied by human beings shall be provided with natural light by means of exterior glazing with an area of not less than 10 Percent of the floor area. Such rooms and spaces shall be provided with natural ventilation by means of exterior openings with an open able area not less than 5 Percent of the total floor area or artificial light and mechanically operated ventilation system as per provisions of this Code.
#### 2.14.6.2
Ventilation in Hazardous Locations: The rooms, spaces or areas where explosive, corrosive, combustible, flammable or highly toxic dust, mists, fumes, vapors or gases are stored or may be emitted due to the processing, use, handling or storage of materials shall be mechanically ventilated.
#### 2.14.6.3
The mechanical ventilation of all hazardous uses shall be segregated or separated from the ventilation of other areas. The emissions generated at work areas shall be confined to the area in which they are generated and shall be removed or discharged outside the building and preventive measures against back flow of such hazardous fumes or gases inside the building shall be installed.
#### 2.14.6.4
Ventilation of Toilets: Toilets shall be provided with fully openable exterior window of at least 0.3 m² in area or a vertical duct not less than 62500 mm² in crosssection for the first water closet, with additional 31250 mm² for each additional fixture or a mechanically operated exhaust system equipped to provide a complete change of air in every 15 minutes. Such system shall be connected to the outside air and the point of discharge shall be at least 1.0 m away from any other opening into the building.
#### 2.14.6.5
Other requirements of water closets are specified in Sec 1.12.4 Chapter 1, Part 3.
### **2.14.7 Sanitation**
All buildings or part of a building classified as Occupancy J shall conform to the provisions of Sec 1.16 of this Chapter and Part 8 of this Code.
### **2.14.8 Shaft and Exit Enclosures**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with Chapter 3, Part 4.
### **2.14.9 Fire Detection, Alarm, Evacuation and Extinguishment System**
All buildings shall conform to regulations set forth in Part 4 of this Code.
### **2.14.10 Explosion Control**
Explosion control, equivalent protective devices or suppression systems or barricades shall be installed to control or vent the gases resulting from deflagrations of dusts, gases or mists in a room or area, building or other enclosures to minimize structural or mechanical damage.
Walls, floors and roofs separating a use from explosion exposure shall be designed according to the provisions of Chapter 1, Part 6.
Explosion venting shall be designed in exterior walls or roof only. The venting shall be provided to prevent serious structural damage and production of lethal projectiles. The venting design shall recognize the natural characteristics and behaviors of building materials in an explosion. The vents shall be designed to relieve at a maximum internal pressure of 1.0 kPa but not less than the loads required by Chapter 2, Part 6. One or more of the following systems shall be installed to relieve explosion, where applicable:
* (a) Lightweight materials in walls
* (b) Light fastening devices with hatch covers
* (c) Light fastening with outward opening swing doors in exterior walls
* (d) Nonbearing walls with light ties
The venting devices shall discharge vertically or horizontally directly to an unoccupied yard having a width of not less than 16 m on the same plot.
The releasing devices shall be so located that the discharge end shall not be less than 3 m vertically and 6 m horizontally from window openings or exits in the same or adjoining buildings.
### **2.14.11 Special Hazard**
Chimneys, vents and ventilation ducts shall be of noncombustible materials.
All boilers, central heating plants, electrical rooms or hot water supply boiler shall be separated from the rest of the occupancies or uses by not less than 2 hour fire resistive construction.
The devices that generate a spark, flame or glow capable of igniting gasoline shall not be installed or used within 0.5 m of the floor.
Equipment or machinery that produces or emits combustible or explosive dust or fibers shall be provided with an approved dust collecting and exhaust system.
The equipment or systems that are used to collect or process or convey combustible dust or fibers shall be installed with explosion venting or containment system.
## **2.15 Requirements For Occupancy K–Garage Buildings**
Buildings shall be classified as Occupancy K in accordance with Sec 2.1.15.
Exception: Non-separated use mentioned in Sec 2.3.1.
### **2.15.1 Construction, Height and Allowable Area**
The buildings or parts thereof classified as Occupancy K shall be limited to the type of construction set forth in Table 3.2.4 and Sec 2.4.4.2 and shall comply with the other provisions of Sec 1.8 Chapter 1 Part 3, Appendix F and Sec 2.4.2 to meet the requirements and limitations of height and area. With the exceptions mentioned in Sec 2.4.3, all garage floors shall be constructed with not less than 4 hour fire resistance materials.
#### 2.15.1.1
Floors: The floors and spaces where motor vehicles are stored, repaired or operated shall be of noncombustible, liquid-tight construction.
Exception: In floors and areas where no repair works are carried out may be surfaced or waterproofed with asphaltic paving materials.
#### 2.15.1.2
Spill Control: The floors containing hazardous repair or other works shall be recessed a minimum of 100 mm so as to prevent flow of liquids to adjoining areas.
#### 2.15.1.3
Drainage: The buildings and areas shall be provided with approved drainage system to direct the flow of liquids to an approved location or room or area designed to provide secondary containment of the hazardous materials and fire protection water.
The drains shall be designed with adequate slope and section to carry the design discharge of the sprinkler system. The material used in the drains shall be suitable for drainage of the storage materials.
The quality of discharged liquids must attain approved level before discharging into the public sewer or natural stream or river.
#### 2.15.1.4
Smoke and Heat Vents: Smoke and heat vents shall be provided in areas or rooms containing hazardous materials exceeding the exempt amount of Table 3.2.5.
### **2.15.2 Location on Property**
Buildings of Occupancy K shall comply with the requirements for location on property and fire resistive exterior walls and openings as specified in Sec 2.4.1.
### **2.15.3 Access and Exit Facilities and Emergency Escapes**
Facilities for access and exit and emergency escape shall comply with the provisions set forth in Sec 1.6 Chapter 1 Part 3, Chapter 3 Part 4 and Appendix F.
### **2.15.4 Lighting, Ventilation and Sanitation**
All buildings or part of a building classified as Occupancy K shall conform to the provisions of Sec 1.16 Chapter 1 Part 3, Chapters 1 and 3, Part 8.
### **2.15.5 Shaft and Enclosure**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with Chapter 3 Part 4.
### **2.15.6 Fire Detection, Alarm, Evacuation and Extinguishment System**
All buildings shall conform to regulations set forth in Part 4 of this Code.
## **2.16 Requirements For Occupancy L–Utility Buildings**
Buildings shall be classified as Occupancy L in accordance with Sec 2.1.16.
### **2.16.1 Construction, Height and Allowable Area**
The buildings or parts thereof classified as Occupancy L shall be limited to the type of construction set forth in Table 3.2.4 and Sec 2.4.3, and shall comply with the provisions of Sec 1.8 Chapter 1 Part 3, and Sec 2.4.2 to meet the requirements and limitations of height and area.
### **2.16.2 Location on Property**
Buildings of Occupancy L shall comply with the requirements for location on property and fire resistive exterior walls and openings as specified in Sec 2.4.1.
### **2.16.3 Access and Exit Facilities and Egress System**
Facilities for access and exit and egress system shall comply with the provisions set forth in Sec 1.6 Chapter 1 Part 3 and Chapter 3 Part 4.
### **2.16.4 Lighting, Ventilation and Sanitation**
All buildings or part of a building classified as Occupancy L shall conform to the provisions of Sec 1.16 Chapter 1 Part 3, Chapters 1 and 3, Part 8.
### **2.16.5 Shaft and Enclosure**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with Chapter 3 Part 4.
### **2.16.6 Fire Detector, Alarm, Evacuation and Extinguishment System**
All buildings shall conform to regulations set forth in Part 4 of this Code.
### **2.16.7 Special Hazard**
#### 2.16.7.1
Since the nature of use of this occupancy involves hazard, special consideration for maintenance and operational safety must be ensured. Depending upon the degree of hazard involved, this occupancy type may have separate and isolated structure.
#### 2.16.7.2
Chimneys and vents and ventilation ducts shall be of noncombustible materials.
All boilers, central heating plants, electrical rooms or hot water supply boiler shall be separated from the rest of the occupancies or uses by not less than 2 hour fire resistive construction.
The devices that generate a spark, flame or glow capable of igniting gasoline shall not be installed or used within 0.5 m of the floor.
Equipment or machinery that produces or emits combustible or explosive dust or fibers shall be provided with an approved dust collecting and exhaust system.
The equipment or system that is used to collect or process or convey combustible dust or fibers shall be installed with explosion venting or containment system.
## **2.17 Requirements For Occupancy M–Miscellaneous Buildings**
Buildings shall be classified as Occupancy M in accordance with Sec 2.1.17.
### **2.17.1 General**
The buildings or parts thereof classified as Occupancy M shall be limited to the type of construction set forth in Table 3.2.4 and shall comply with the requirements of Sections 1.8 and 2.4.2 to meet the requirements of height and area limitations.
Any building or portion thereof that exceeds the limitations provided in this Chapter shall be classified in the occupancy group other than M that it most nearly resembles.
### **2.17.2 Location on Property**
The location on property for Occupancy M shall conform to Sec 2.4.1.
### **2.17.3 Access and Exit Facilities and Emergency Escapes**
Access and exit facilities for Occupancy M shall comply with the specification set in Sec 1.6 Chapter 3, Part 4.
### **2.17.4 Lighting, Ventilation and Sanitation**
All buildings or part of a building classified as Occupancy M shall conform to the provisions of Sec 1.16 Chapters 1 and 3, Part 8.
### **2.17.5 Shaft and Exit Enclosures**
Elevator shafts, vent shafts and other vertical openings shall be enclosed conforming to the provisions of Tables 3.3.1 (a) and (b). Exit requirements shall comply with the requirements of Chapter 3, Part 4.
### **2.17.6 Fire Detection, Alarm, Evacuation and Extinguishment System**
All buildings shall conform to regulations set forth in Part 4 of this Code.
**Table 3.2.6: A** **Z List of Occupancy Classification**
| **Use or Occupancy** | **Brief Description** | **Occupancy**
**Class/Sub-class** |
| --------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| | **A** | |
| Adhesives
manufacture | Excluding manufacture of basic
components | G or J depending on
nature of materials
involved |
| Advertising displays
manufacture | | G |
| Agricultural machinery
manufacture | Including repairs | G |
| Agriculture | Without nuisance or sales limitation | H |
| Agricultural | Small farm house, (limited to storage
quantity)
Large farm house, storage quantity
unlimited | F
H or J |
| | Small grain processing unit, (limited
to quantity)
Large grain processing unit, quantity
unlimited | G
G or J |
| Aircraft manufacture
(including parts) | | G or J depending on
nature of materials
and process
involved |
| Airports | | MIXED USE
(depending on
detail requirement) |
| Amusement parks,
children's | (See children's amusement parks) | - |
| Amusement park
activities | | I |
| Animal | Animal hospitals | F |
| | Animal pound (for stray and lost animal) | H |
| | Animal crematorium | G |
| | Killing establishments, for retail sales | F |
| | Slaughtering, processing and packing | G |
| Antique stores | | F |
| Apartments | (see residential) | |
| | in walkup buildings | A |
| | In high rises | A |
| | in housing complex | A |
| Apartment hotels | | A5 |
| Apparel | (See clothing) | |
| Appliances | Electrical appliance Manufacturing | G |
| | Television, radio, phonograph or
household appliance stores, (Limited
as to floor areas)
Television, radio, phonograph or
household appliance stores,
(Unlimited)
Household appliance repair shops | F
F
F |
| Arenas, auditoriums,
or stadiums | See Assembly (Limited as to capacity)
See Assembly (Unlimited) | I
I |
| Art Galleries | Commercial (sales included)
With exhibition open to public
viewing for limited period (sales
included) | F
I |
| Art goods
manufacture, religious
temple or church,
excluding foundry
operations | | G |
| Art metal craft shops | | F |
| Art needle work | Six occupants or less
More than six occupants
(see industrial) | Non-separated use
to A1 and A2
Occupancy
G |
| Artist's supply stores | | F |
| Asphalt or asphalt
products | Manufacture | J |
| Assembly | Large assembly with fixed seats | I1 |
| | Small assembly with fixed seats | I2 |
| | Large assembly without fixed seats | I3 |
| | Small assembly without fixed seats | I4 |
| | For sport facilities | I5 |
| Athletic equipment
manufacture | | G |
| Athletic goods stores | | F |
| Auctions rooms, open
to public | | I |
| Auditoriums | See assembly | I |
| Automatic laundries | | G |
| Automobiles | Dead Storage | H |
| | Driving Schools | E |
| | Glass or mirror shops | F |
| | Washing | K |
| | Manufacture, including parts, or
engine rebuilding | J |
| | Rental establishments | K |
| | Repairs, body | K |
| | Repairs, without body repairs | K |
| | Sales open or enclosed | K |
| | Seat cover or convertible top | F |
| | establishments, selling or installation | |
| | Showrooms, no repair services | K |
| | Supply stores, no repair services | F |
| | Tire sales establishments, limited to
quantity | F |
| | Tire sales establishments, unlimited | J |
| | Wrecking establishments | G |
| Automotive service | Limited as to total area | K |
| stations | Unlimited... | K |
| Awnings | Custom shops | H |
| | Manufacture, with no limitation on | G |
| | production or on floor area | |
| | **B** | |
| Bakeries | Home-made, six or less occupants
(baking included) | non-separated use
to main occupancy |
| | Large scale, more than six occupants
(baking included)
Sales only | G
F |
| Banks, | Including drive-in banks | E |
| Banquet halls | | I |
| Bar, alcoholic | | I |
| Barber shops | | F |
| Barns | | H |
| Barracks | (See residential) | A4 |
| Baths, steam | | I |
| Beaches, commercial | | Not applicable |
| Beauty parlors | | F |
| Beverages | Bottling works | G |
| | Manufacture, Alcoholic | J |
| | Non-alcoholic | G |
| Bicycle | Manufacture | G |
| | Rental or repair shops
Sales | F
F |
| Billiard parlors | | I |
| Blacksmith shops | small scale (limited to six occupants),
repair or making
Unlimited | F
G |
| Blueprinting
establishments | drawing printing | G |
| Boarding houses | (See residential) | A |
| Borstals | | C |
| Boatels | | A |
| Boats or ships | Bailer works at port or dock | J |
| | Breaking | J |
| | Building or repair, for boats less than
200 ft. in length | J |
| | Building or repair, for boats 200 ft. or
more in length | J |
| | Docks, for small pleasure boats | Not applicable |
| | Fuel sales, open or enclosed | |
| | Un- restricted as to location
Restricted as to location
Rentals opened or enclosed
Sales opened or enclosed
Showrooms, with no repair services.. | F
J
F
F
F |
| | Storage, repair, or painting, including
the incidental sales of boats, boat
parts, or accessories, with restrictions
on boat size and setbacks | G |
| Bone distillation | | G or J depending on
process or material
used |
| Botanical garden
structures | | M |
| Book | Binding (see printing)
Hand binding or tooling | G |
| | Store | F |
| Bottling works, for all
beverages | | G |
| Bowling alleys | Limited as to number of lanes
Unlimited | I
I |
| Breweries | | G |
| Brick manufacture | | J |
| Brush or broom
manufacture | | G |
| Building materials sales | open or enclosed, limited as to lot area
Yards, for sales, storage, or handling,
open or enclosed, unlimited as to lot
area except in the case of lumber
yards | F
F |
| Bungalow | (See residential) | A |
| Business | Offices
Research and testing laboratories
Essential services | B1
B2
B3 |
| Bus stations | With less than 10 berths
With 10 or more berths | K (bus area) and I
(passenger area)
MIXED (as per
detail requirement
including K and I) |
| Bus stops | see Bus stations | |
| Business machines | Manufacture
Small, repair shops
Stores, sales, or rentals.. | G
F
F |
| Business schools or
colleges | | B |
| Buying house | storage restricted to sample | E |
| (garments) | | |
| | **C** | |
| Café | Six persons or less
More than six persons (see
mercantile) | Non-separated use
to main Occupancy
F |
| Cafeteria | With commercial kitchen
Without commercial kitchen | MIXED (G and I)
I |
| Camera and photo
equipment | Manufacture | G |
| Camps, overnight or
outdoor day | | MIXED (A, I and
other depending on
the nature of use) |
| Candy stores | | F |
| Canneries, including
food products | | J |
| Canteen | With or without cooking facility | I |
| Canvas or canvas
products manufacture | | G2 |
| Cargo terminal | containing low fire-risk materials
containing moderate fire-risk
materials | H
H |
| | containing high fire-risk materials | J |
| Carnivals, temporary | | I5 |
| Carpentry shops | | G |
| Carpet | Cleaning establishments... | J or G depending on
the nature of
materials involved |
| | Manufacture | G |
| | Carpet, rug, linoleum or other floor
covering stores Unlimited | F |
| Carport | Roofed wall less shelter for car | K or H depending
on the nature of use |
| | Automated mechanical parking | K or H depending
on the nature of use |
| Catering establishments | Commercial kitchen | G |
| | Office | E |
| | Storage, open or enclosed | H |
| | Storage for temporary structure's
fabrication material | J |
| Cattle shed, stables | | H |
| Cement manufacture | | G2 |
| Cemeteries | | H |
| Ceramic products | Manufacture
Display and sales | G or J based on
nature of material
used
F |
| Chamber, doctors' or
| 50 or less occupants | E |
| dentists',
(outpatient only) | above 50 occupants | D |
| Charcoal manufacture | | G |
| Chemicals | Compounding or packaging
Manufacture | G or J depending on
nature of materials
involved
G or J depending on
nature of materials
involved |
| Child care home | | C |
| Child care institution | | C |
| Children's amusement
parks | Small
Medium size
Large size
Unlimited as to size | I
I
I
I |
| Churches, with fixed
pews | (See Assembly with fixed seats) | I |
| Cigar stores | | F |
| Cinema hall | (See Assembly with fixed seats) | I |
| Cineplex | (See Assembly with fixed seats) | I |
| Circuses, temporary | (See Assembly) | I |
| Class room | School, college or university | B |
| Clay manufacture | | G |
| Clay pits | | Not applicable |
| Cleaning or cleaning
and dyeing
establishments | (See dry cleaning).... | |
| Clinics | With inpatient
Only outpatient, limited to quantity
(see chambers, doctors' or dentists')
Only outpatient, unlimited
With diagnostic facilities (see
diagnostic facilities) | D
D |
| | Government community clinic | E |
| Coaching centre | (See educational facilities) | B |
| Cold storage | | H |
| Composite textile mill | | G or J depending on
nature of material
and process used |
| Cottage industries | Small, fifty or less workers
(see industrial facilities)
Large, more than fifty workers…
(see industrial facilities) | G1
G1 or G2 depending
on the nature of
material and
process used |
| Clock | Manufacture | G |
| | Stores or repair shops | F |
| Clothing | Accessory stores | F |
| | Custom manufacture or altering for
retail | F |
| | Manufacture
Rental establishments | G or J depending on
nature of the
material involved
F |
| | Store, Limited as to floor area | F |
| | Store, Unlimited | F |
| Clubs Non-commercial
(members only) | Including accommodation
Night-club
All types except those with outdoor
swimming pools | MIXED (A and I)
I |
| Clubs, for public use | Excluding accommodation
Including accommodation | I
MIXED (I and A or
other occupancies
depending upon
nature of use) |
| Clubs, Sporting | | MIXED (I and A or
other occupancies
depending upon
nature of use) |
| **Use or Occupancy** | **Brief Description** | **Occupancy** |
| | | **Class/Sub-class** |
| Coal | Products manufacture
Sales, open or enclosed, Limited as to
plot area
Unlimited (see coal storage)
Storage, open or enclosed | J
J
J
J |
| Coin stores | | F |
| Condensed and
powdered milk | Manufacture | J |
| Coke products | Manufacture | J |
| Colleges or universities | See educational facilities | B |
| Colony, government
or non-government | | MIXED (A and other
occupancies
depending on use) |
| Commercial building | (see business and/or mercantile) | |
| Commercial parking
garages or plots | (See garages) | K |
| Community centers | With commercial kitchen
Without commercial kitchen | MIXED (G and I)
I |
| Concrete batching | | G |
| Concrete products
manufacture | | G |
| Construction
machinery | Manufacture, including repairs | G |
| Container terminal | | H or J (According
to the hazard
classification
regulation of the
port authority) |
| Contractors'
establishments | Electrical, glazing, heating, painting,
paper hanging, plumbing, roofing, or
ventilating
Contractors' yards | F
Not applicable |
| Convalescent homes | (See nursing homes) | |
| Convents | | MIXED (A, B and
I) |
| Cork products | Manufacture | G |
| Cosmetics or toiletries | Manufacture.. | J |
| Costume rental
establishments | | F |
| Cottage, tourist | (See residential) | A5 |
| Cotton ginning or
cotton wadding or
liner manufacture | | J |
| Court houses | | I |
| Crate manufacture | | G or J depending on
the material and
process involved |
| Crematoriums | Animals.
Human. | J
MIXED (J and I) |
| Cultural center | | Mixed (depending on
detail requirement) |
| | **D** | |
| Dance halls | Public | I |
| Dance School | | A |
| Dance studios | (see studios) | |
| Day camps, outdoor | | I |
| Day care Centre | With six or less children | Non-separated use
to Residential
Occupancy |
| | More than six children | C |
| Decorator's
establishment | Office
Storage, separated | E
H or J depending
upon the material
involved |
| Defense Buildings, for
critical national
defense capabilities | | Not Applicable |
| Delicatessen stores | (See food stores) | F |
| Dental | Instruments manufacture
Laboratories (See laboratories,
medical or dental) | G |
| Department stores | not exceeding 300 m²
more than 300 m² | F1
F2 |
| Diagnostic facilities,
medical | Outpatients only | D |
| Diaper supply
establishments | | H |
| Disinfectants
manufacture | | G |
| Dispensaries | Attached to hospital
See drug store | L
F |
| Dormitories | Universities or colleges (above 12
grade) | A |
| | Schools (12 grade or below) | C |
| Drafting instruments | Manufacture | G |
| Dressmaking shops,
custom | | F |
| Drinking places, non-
alcoholic | (See cafe) | |
| Drive-in theaters | | I |
| Drug stores | | F |
| Dry cleaning or
clothes pressing
establishments | Limited as to floor area, solvents and
machine capacity | G or J depending on
the process and
quantity of material
used |
| Dry cleaning or
cleaning and dyeing
establishments | Without restrictions | G or J depending on
the process and
quantity of material
used |
| Dry Cleaning, using
other than flammable
liquids in cleaning or
dyeing operations | | G |
| Dry goods stores | Limited as to floor area | F |
| | Unlimited | F |
| Dumps | | Not applicable |
| Dyeing facilities/
industries | **E** | J |
| Eating or drinking
places | With restrictions on entertainment
(see Assembly)
Without restrictions on entertainment
or dancing but limited to location in
hotels (see Assembly)
Without restrictions (See assembly) | I
I
I |
| Eco park structures | | MIXED (depending
upon the nature of
use) |
| Educational facilities | Up to higher secondary level | B1 |
| | Training and above-higher-secondary
education | B2 |
| | Pre-school facilities | B3 |
| Electric | Power or steam generating plants | G |
| | Substations, Public transit or railroad | G |
| | Substations, as part of public
distribution system | G |
| | Substations, low to medium voltage
step down, at consumers' end | L |
| ElectricalAppliance | Manufacture | G or J depending
upon the process or
material to be used |
| | Stores (including television, radio,
phonograph or household appliances)
Contractors (See contractors'
establishments) | F |
| | Equipment assembly, not including
electrical machinery | G |
| | Supplies, manufacturing | G |
| Electronics
manufacturing | | J |
| Electrolysis works | | J |
| Electrotyping or | Limited to quantity | F |
| stereotyping | Unlimited (see printing) | G |
| Embassy or High-
commission or
Consulate | | MIXED (depending
on detail
requirement) |
| Engine | including rebuilding or reconditioning | J |
| Engraving or photo- | Limited to quantity | F |
| engraving | Unlimited (see printing) | G |
| Excelsior manufacture | | J |
| Exhibition hall | See assembly | I |
| Exterminators | See pest control | F |
| | **F** | |
| Fabric stores | | F |
| Factory | | G or J (depending
on process and
material involved) |
| Fairs, temporary | | MIXED (I and F) |
| Feathers | Bulk processing, washing, curing, or
dyeing
Products manufacture, except
washing , curing or dyeing | J
J |
| Felt | Bulk processing, washing, curing, or
dyeing
Products manufacture, except
washing, curing or dyeing | G
G |
| Fertilizer manufacture | | J |
| Field hospital,
temporary | With provision for ambulance access
(to parks and play grounds) | E |
| Filling stations | (See refueling station) | B |
| Film, photographic | Manufacture | G |
| Fire Stations | | E |
| Fish products, packing
or processing | | G |
| Fishing tackle or
equipment rental or
sales | | F |
| Flats | (see residential)
In walkup buildings
In high rises
in housing complex | A
A
A
MIXED (A and
other occupancies) |
| Florist shops | | F |
| Food | Products processing, except meat
slaughtering or preparation of fish for
packing
Stores, including supermarkets,
grocery stores, meat markets, or
delicatessen stores | G
F |
| Foundries | Ferrous or non-ferrous | G or J (depending
on process and
material involved) |
| Fraternity houses | (See colleges or universities) | |
| Freight depot | See storage and hazardous buildings | H and/or J |
| Frozen food lockers | | J |
| Fuel briquettes
manufacture | | G |
| Fuel sales, open or
enclosed | Limited up to exempted quantity
Unlimited, See coal storage or
petroleum storage | F
J |
| Funeral
establishments | | I |
| Fungicides
manufacture | | G |
| **Use or Occupancy** | **Brief Description** | **Occupancy** |
| | | **Class/Sub-class** |
| Fur | Goods manufacture, not including
tanning or dyeing
Tanning, curing, finishing, or dyeing | G
J |
| Furniture | Custom shop, floor area of 100 m² or
less
Custom shop, floor area over 100 m²
Manufacture
Store, Limited as to floor area | F
G
J or G depending
upon nature of
materials involved
F |
| | Store, Unlimited | F |
| Furriers shops, custom | | F |
| Freight depot | | H or J depending on
the nature of
material involved |
| | **G** | |
| Garages | Parking garage | K1 |
| | Private garage | K2 |
| | Repair garage and show-rooms | K3 |
| Garbage incineration
or reduction | | G |
| Garden shed | | M |
| Garden supply stores | | F |
| Gardens, truck | (See agriculture) | |
| Garments industries | | G |
| Gas, fuel | Manufacture
Distribution regulatory system (DRS) | J
G |
| Gas manufacture for | Medical purpose
Hot-works (welding) | J
J |
| Gasoline service
stations | (See refueling stations) | |
| Gelatin manufacture | | G |
| Generating plants,
electric or steam | | G |
| Gift stores | | F |
| Glass | Cutting shops
Manufacture
Products manufacture from
previously manufactured glass | F
G
G |
| Glazing contractor's
establishment | (See contractors' establishments) | F |
| Glue manufacture | | G |
| Godown | See storage buildings | |
| Golf | Courses | Not applicable |
| | Courses, miniature
Driving ranges | I
I |
| Grain | Milling or processing
Storage | J
J |
| Graphite or graphite
products | Manufacture | G |
| Gravel pits | | Not applicable |
| Grocery stores | | F |
| Group homes | Segregation of occupants on the basis
of age group and disabilities
(See institutional) | C |
| Gypsum production
industry | | J |
| Gymnasiums | Less than 300 occupants
300 or more occupants
Commercial without spectator gallery
(max 50 occupants) | I
I |
| | **H** | |
| Hair | Bulk processing, washing, curing, or
dyeing
Products manufacture (except
washing, curing, or dyeing) | G
G |
| | Products manufacture, custom | G |
| Hall, for incidental
show (picture, drama,
theatre) | (See assembly) | I |
| Hardware | Manufacture | G |
| | Stores | F |
| | Bodies manufacture | G |
| | Repair shops | F |
| Hazardous buildings | Explosion-hazard building | J1 |
| | Chemical-hazard building | J2 |
| | Biological-hazard building | J3 |
| | Nuclear-hazard building | J4 |
| Health centers | With inpatient | D |
| | Without inpatient (not more than 50
occupants)
Government operated health centers | E
E or D (depending
upon the facilities) |
| Healthcare facilities | Normal medical facilities | D1 |
| | Emergency medical facilities | D2 |
| Health club | | I |
| Heating contractor's
establishment | (See contractors' establishments) | |
| Heat, ventilation and
air-conditioning | Without repair facilities | F |
| equipment showrooms | | |
| Heliports | | G |
| Hemp products
manufacture | | G |
| High Commission | See embassy | |
| Home for care | of the old and infirm (see institution)
of mentally disabled (see institution) | |
| Home office | Not more than 6 occupants | Non-separated use
of Occupancy A |
| Hosiery manufacture | | G |
| Hospital, except
animal hospital | As part of disaster preparedness
program | D |
| | Casualty unit | D |
| | Emergency unit | D |
| | Non-profit or voluntary, and related
facilities | D |
| | Proprietary and related facilities | D |
| Hostels | For adults | A |
| | For children | C |
| Hotels | Transient | A |
| | Apartment hotel
Starred hotel | A
MIXED |
| Household | Appliance repair shops | F |
| | Appliance stores (See appliances
television, radio, phonograph, or
household appliance stores) | F |
| Housing, complex
multi-storied | | MIXED (see appendix) |
| Housing, cluster | | MIXED (see appendix) |
| Housing, low-income | | MIXED (see appendix) |
| Housing, minimum
standard | | MIXED (see appendix) |
| Housing, rehabilitation | | MIXED (see appendix) |
| | **I** | |
| Ice cream stores | | F |
| Ice | Manufacture, dry or natural
Sales, open or enclosed Limited as to
lot area
Unlimited | G or J (depending
on the process or
material used)
F
F |
| Incineration or
reduction of garbage,
offal, or dead animals | | G |
| Indoor facility, for
amusement park | | I |
| Industrial buildings | Low-hazard Industries
Moderate-hazard Industries | G1
G2 |
| Infirmaries | | C |
| Ink or inked ribbon
manufacture | | G or J depending on
nature of materials
involved |
| Inns | See residential | A |
| Insecticides
manufacture | | G or J depending on
nature of materials
involved |
| Institution | For care of children | C1 |
| | Custodial, for physically capable
adults
Custodial, for physically incapable
adults
Penal or mental, for children | C2
C3
C4 |
| | Penal or mental, for adults | C5 |
| Institutions, | With sleeping accommodations | A |
| philanthropic or non-
profit | Without sleeping accommodations | |
| Interior decorating
establishments | Limited as to floor area for
processing, servicing, or repairs
Unlimited, see furniture, textiles or
upholstering | F
F |
| Irradiation plant | | J |
| | **J**
| |
| Jail | see prisons | |
| Jewelry | Manufacture | G |
| | Costume | G |
| | From precious metals | G |
| | Shops | F |
| Junk Yards | | Not applicable |
| Jute products
manufacture | | G or J (depending on
quantity or process) |
| Juvenile correctional | For children (see assembly) | |
| center | | |
| | **K** | |
| Kennels | | H |
| Kindergarten | See educational facilities | B |
| Knitwear industries | | G2 |
| | **L** | |
| Laboratories | Medical or dental, for research or
testing, with limitations on
objectionable effects
Research, experimental, or testing,
unlimited
Radiological laboratory, see
radiological facilities
Pathological laboratory | E
(G or J) and H
depending on
process or material
used in compliance
with safety standards
G (in compliance
with safety standards) |
| | Microbiological laboratory, for
diagnostic facility
Microbiological laboratory, for
research | G or J depending on
process or material
used in compliance
with safety standards
G or J depending on
process or material
used in compliance
with safety standards |
| | Microbiological laboratory, for
academic facility | G or J depending on
process or material
used in compliance
with safety standards |
| Lampblack
manufacture | | G |
| Laundries, with no
limitations on type of
operation | | G |
| Laundry
establishments, hand
or automatic self-
service | | G |
| Lavatory, public | see public toilet | |
| Leather | Tanning, curing, finishing or dyeing
Goods stores
Products manufacture | J
F
G |
| Libraries | Reading area (see assembly) | I |
| | Stack area (see storage)
Reading and stack area combined | H
MIXED (I and H) |
| Lillah boarding | For children (see institutional) | C |
| | For adults (see residential) | A |
| Linen supply
establishments | | |
| Linoleum | Manufacture
Stores (See carpet stores) | J |
| Liquor stores, package | | F |
| Livestock | Storage, more than six castles | H |
| | Slaughtering or preparation for
packing | G |
| Loan offices | | E |
| Locksmith shops | | F |
| Lodging | See residential | A |
| Luggage | Manufacture | G |
| | Stores | F |
| Lumber | Processing or woodwork, bulk | G |
| | Sales, Limited as to lot area
Sales, Unlimited | G
G |
| | Yard, Limited as to lot area | G |
| | Yard, Unlimited | G |
| | **M**
| |
| Machine | Shops including tool, die or pattern
making | G |
| | Tools manufacture | G |
| Machinery | Manufacture or repair, Heavy
Miscellaneous or electrical equipment
Rental or sales establishments | G or J depending on
material and process
G or J depending on
material and process
F |
| | Repair shops | F |
| Machines, business | (See business machines) | |
| Madrasa | (See institution) | |
| Manure storage | | H |
| Markets | Retail, including meat (See mercantile)
Wholesale, produce or meat
(See mercantile) | F
F |
| Masseurs | | F |
| Matches manufacture | | J |
| Mattress manufacture,
rebuilding or
renovating | | J |
| Meat | Markets, Retail (See food stores)
Markets, Wholesale | F
F |
| | Slaughtering or preparation for packing | G |
| Medical | Appliances, Custom manufacture | G |
| | Appliances, Manufacture
Stores | G
F |
| | Instruments, manufacture
Laboratories (See laboratories, medical)
Offices or group medical centers,
Limited as to location within building
Offices or group medical centers,
Unlimited | G
E
E |
| Meeting halls | See Assembly | I |
| Mess houses | (See residential) | |
| Metal Fabrication
industry | | J |
| Metal Assembly
industry | | J |
| Metals manufacture | Alloys or foil, miscellaneous
Casting or foundry products, heavy
Finishing, plating, grinding,
sharpening, polishing, cleaning, rust
proofing, heat treatment, or similar
processes | G
G
G |
| | Ores reduction or refining | G |
| | Products treatment or processing | G |
| | Reduction, refining, smelting, or
alloying | G |
| | Stamping or extrusion | G |
| | Treatment or processing | G |
| Mental institution | Without detention facilities | D |
| Mental hospitals | (See institution) | C |
| Mercantile | Small shops and markets | F1 |
| | Large shops and markets
Refueling station | F2
F3 |
| Mill | (See industrial and/ or hazardous
buildings) | G or J (depending on
material or process) |
| Mill works, and
woodworking, wood
distillation and particle
boards manufacturing | | J |
| Millinery shops | | F |
| Mining machinery
manufacture | Including repairs | G |
| Mirror silvering shops | | G |
| Miscellaneous | Special structures | M1 |
| buildings | Fences, tanks and towers | M2 |
| Monasteries | | MIXED |
| Monument | Sales establishments, with incidental
processing to order | F |
| | Works, with no limitations on
processing | G |
| Mosque | (See assembly) | I |
| Motels | (See residential) | A |
| Motion picture
production and
filming facilities | | MIXED (G and other
Occupancies as
required) |
| Motorcycles | Manufacture | G |
| | Repairs, body | G |
| | Repairs, except body repairs
Sales open or enclosed
Showrooms, with no repair services
(See garage) | G
F
K |
| Motor freight stations | See truck terminals | |
| **Use or Occupancy** | **Brief Description** | **Occupancy** |
| | | **Class/Sub-class** |
| Motor vehicles | Dead storage | H |
| | Moving or storage offices, Limited as
to storage
Unlimited | K
K |
| Movie theatre | See assembly | I |
| Museums | See assembly | I |
| Music stores | | F |
| Music studios | See studios | |
| Musical instruments | Manufacture, Excluding pianos and
organs
Including pianos and organs… | G1
G2 |
| | Repair shops… | G1 |
| | **N** | |
| Newspaper publishing | Printing
Office | MIXED (G and E)
G
E |
| Newsstands, open or
closed | | F |
| Novelty products
manufacture | | G |
| Novitiates… | See institution | A |
| Nuclear medicine
facilities | see radiological facilities | |
| Nuclear plant | | J |
| Nurseries | See agriculture | |
| Nursing homes | Philanthropic or non-profit
Private | C or D depending on
the type of occupants
and nature of use
C or D depending on
the type of occupants
and nature of use |
| Nursery schools | See pre-school | B |
| **Use or Occupancy** | **Brief Description** | **Occupancy**
|
| | | **Class/Sub-class** |
| | **O** | |
| Oakum products
manufacture | | G |
| Office equipment or
machinery repair
shops | | F |
| Office or business
machine stores | sales or rental | F |
| Offices | General
Business, professional orGovernmental
(see business occupancy)
Dental, medical, or osteopathic
(See medical offices)
Wholesale, with storage restricted to
samples (see business occupancy) | E
E
E
E |
| Offices, small | Architect's/engineer's/ consultant's
(Limited to six occupants)
Architect's/engineer's/consultant's
( more than six occupants) | Non-separated use
of Occupancy A
E |
| Oil cloth manufacture | | J |
| Oil sales, open and
enclosed | Limited as to lot area
Unlimited (See petroleum or
petroleum products storage) | F
J |
| Old home | See institution | C |
| Optical | Equipment manufacture | G |
| | Goods manufacture | G |
| Orphanage | See institution | C |
| Optician or optometrist
establishments | | F |
| Orthopedic | Appliances, Custom manufacture | G |
| | Manufacture
Stores | G
F |
| | Instruments, manufacture | G |
| Osteopathic offices | (See medical offices) | |
| | | **Class/Sub-class** |
| | **P** | |
| Packing or crating
establishments | | G2 |
| Packing materials
manufacture | | G2 |
| Pagoda | See Prayer hall | |
| Paint | Manufacture | J |
| | Stores, limited to quantity
Stores, unlimited | F
H |
| Painting contractors | (See contractors' establishments) | |
| Paper | Mills (See wood pulp or fiber) | G |
| | Products manufacture | G |
| | Stock companies | H |
| Paper-hanging
contractors | (See contractors' establishments) | |
| Parish houses | | A |
| Parks, public or
private | With provision for emergency vehicle
access as part of disaster preparedness
program | Not applicable |
| Park structures | | M |
| Parking garages, public | See garage, parking | K |
| Parking lots, public | See garage, parking | K |
| Passenger stations and
terminals | Small, passenger station
Large, passenger station or terminal
Passenger and freight terminal | MIXED (depending
on nature of use)
MIXED (depending
on nature of use)
MIXED (depending
on nature of use) |
| Peat storage | | H |
| Perfumed or perfumed
soaps | compounding only, not including
soap manufacture | J |
| Pest control | Exempted quantity only | F |
| Pet shops | | F |
| Petrol pump | See refueling station | F |
| Petroleum or
| Refining | J |
| petroleum products | Storage and handling | J |
| Pharmaceutical
products manufacture | | G or J depending on
nature of materials
used |
| Philanthropic, religious
or non-profit activities | | MIXED (depending
on nature of use) |
| Phonograph | Repair shops | F |
| | Stores (See appliances) | F |
| Photocopying and
book binding | Binding limited in quantity | F |
| Photographic | Developing or printing establishment,
Retail | F |
| | Developing or printing establishment,
Wholesale, Limited as to floor area | H |
| | Developing or printing establishment,
Wholesale, Unlimited | H |
| | Equipment, Manufacture (film) | J |
| | Equipment, Manufacture (except film) | G |
| | Stores
Studios | F
F |
| | Supply stores (limited to exempted
quantity) | F |
| Photostatting
establishments | | F |
| Physical culture
establishments | | I |
| Picture framing stores | | F |
| Plants, Industrial | | G |
| Plants, Refrigeration | | G |
| Plastics | Products, manufacture | J |
| | Raw, manufacture | J |
| Plate making | (See printing) | |
| Playgrounds | With provision for emergency vehicle
access as part of disaster preparedness
program | I |
| Plots, parking | (See parking lots, public) | |
| Plumbing | Contractors' establishments
Equipment manufacturer (See tools or
hardware manufacturing)
Showrooms, without repair facilities | F
F |
| Police Stations | | E |
| Pool halls | | I |
| Porcelain products
manufacture | | G |
| Post offices | | E |
| Poultry | Storage (live)
Killing establishments, for retail sales
on the same zoning lot only
Packing or slaughtering | H
G
G |
| Power plant | | G |
| Power stations | As part of national grid power
distribution system
At consumer's end | E
L |
| Prayer hall | See assembly | I |
| Precision instruments
manufacture | Optical equipment, clocks, or similar
products
Medical, dental, or drafting
instruments, optical goods, or similar
products | G
G |
| Pre-school facilities | See educational | |
| Press club, for journalist | | I |
| Press, printing | See printing | |
| Primary schools | See educational | |
| Printing | Custom | G |
| | Limited as to floor area
Unlimited | G
G |
| Printing, publishing,
dyeing and printing
industries | | J |
| Prisons | See jail | C |
| Produce or meat
markets, wholesale | | F |
| Psychiatric sanatoria | With detention facilities
(see institution) | |
| Public auction rooms | | MIXED (F and/or I) |
| Public transit yards | | Not applicable |
| Publishing | With printing | G |
| | Without printing | E |
| Pumping stations | Water or sewage (for city supply
system) | G |
| | Dedicated to consumer | U |
| | **Q** | |
| Quarter, Staff | Government or non-government | A or Mixed (See |
| | | appendix) |
| | **R** | |
| Racetracks | | I |
| Radio | Appliance repair shops
Stores
Studios, with less than six occupants
Studios, without transmission tower
Studios, with transmission tower
(see radio station) | F
F
Non-separated use
to main Occupancy
E |
| | Towers, non-accessory | M |
| Radio station | | Mixed (depending
on the type of use) |
| Radiological facilities,
medical | In compliance with the standard of
atomic energy commission | D |
| Radioactive waste
disposal services | | J |
| Railroad | Equipment manufacture, including
railroad cars or locomotives
Passenger stations
Right-of-way
Substations | G or J depending on
the material and
hot-work used
I
Not applicable |
| | Small or medium size
Large
Railroads, including rights-of-way,
freight terminals, yards or
appurtenances, or facilities or services
used or required in railroad operations,
but not including passenger stations | G
G
Not applicable |
| Rail station | | Mixed (depending
on the type of use) |
| Record stores | | F |
| Recreation centers,
non-commercial | | I |
| Recreation piers | See assembly | I |
| Recreational vehicles
manufacturing | | J |
| Rectories | | A |
| Reducing salons | | I |
| Reformatories | See institutional facilities | |
| Refreshments stand,
drive-in | | I |
| Refrigerating plants | | G |
| Refueling station | Petroleum product storage within
exempted quantity | E |
| Refuse incinerators | | J |
| Religious or church
art goods manufacture | | G |
| Research
establishment | dealing with non-hazard or low
hazard materials only | E |
| Residences | Single-family detached
One-family semi-detached or two-
family detached or semi-detached
Boarding or rooming houses
Rest homes (See nursing homes) | A
A
A |
| Residential | Single family dwelling
Two family dwelling
Flats or apartments | A1
A2
A3 |
| | Mess, boarding house, dormitories
and hostels | A4 |
| | Hotels and lodging houses | A5 |
| Rest Houses | | |
| Restaurant | Dining area | I |
| | Performing area, limited | I |
| | Kitchen and storage | L |
| Reviewing stand | | I |
| Riding academies,
open or enclosed | | E and H |
| Roofing contractors'
establishments | | F |
| Rooming houses | See residential | A |
| Rubber | Processing or manufacture, natural or
synthetic
Products manufacture (excluding all
natural or synthetic rubber processing) | J
J |
| Rug stores | (See carpet stores) | |
| | **S** | |
| Sail-making
establishments | | F |
| Salvage storage | | H |
| Sand pits | | Not applicable |
| Saloon, hair dressing | | F |
| Sanatoriums | With detention facilities (see institution)
Without detention facilities | C
D |
| Sawmills | | G |
| Scenery construction | | G |
| School (see | Dormitories, for children | C |
| educational) | Nursery, kindergarten, elementary or
secondary schools
Trade or other schools for adults,
limited as to objectionable effects
Trade schools for adults, unlimited
For physically challenged, without
accommodation | B
B
B
B |
| | For mentally challenged, without
accommodation | B |
| Scrap metal, paper and
rag storage | | H |
| Secondary school | See educational | B |
| Seed stores | | F |
| Seminar halls | For 50 or more occupants, See assembly | I |
| Seminaries | | B |
| Settlement houses | (see housing) | MIXED (A and other
Occupancy depending
on the nature of use |
| Sewage | Disposal plants | G |
| | Pumping stations | G |
| **Use or Occupancy** | **Brief Description** | **Occupancy** |
| | | **Class/Sub-class** |
| Sewing machine
stores, selling
household machines
only | | F |
| Ship chandlers, candle
shops | | F |
| Ship or boat building
or repair yards | For ships 200 ft. in length or over | G |
| Shipping, waterfront | | Not applicable |
| Shoes | Manufacture
Repair shops
Stores | G or J depending on
the process and
material involved
F
F |
| Shops | see definition | F or G (depending
on the process and
material involved) |
| Shop-house | | mixed occupancy
(A and F) or (A, F
and G) |
| Sign painting shops | Limited as to floor area
Unlimited | G
G |
| Silk processing and
spinning | | J |
| Silo, for storage of
grain | | H |
| Silver plating shops,
custom | | G |
| Silverware
manufacture, plate or
sterling | | G |
| Sisal products
manufacture | | J |
| Skating rinks, roller | Indoor
Outdoor | I
I |
| Slag piles | | Not applicable |
| Slaughtering of
animals or poultry | | G |
| Soap or detergents | Manufacture, including fat rendering
Packaging only | J
G |
| Soldering shops | | G |
| Solvent extracting | | J |
| Sorority houses | (See hostel) | A |
| Sports centre | | I |
| Sporting equipment
manufacture. | | G |
| Sporting goods stores | | F |
| Stable for horses | | H |
| Stadiums | Indoor or outdoor, with access for
emergency vehicle as part of disaster
preparedness program | I |
| Staff quarter | see quarter, staff | |
| Stamp stores | | F |
| Station | Rail, bus, air and water way | MIXED (I and other
Occupancy
depending on the
nature of use |
| Stationary stores | | F |
| Statuary, mannequins,
figurines, religious or
church art goods
manufacture,
excluding foundry
operations | | G |
| Steel products | Miscellaneous fabrication or
assembly (without hot-work)
Structural products manufacture | G
J |
| Stock yards or
slaughtering of
animals or poultry | | G |
| Stone processing or
stone products | | G |
| Storage buildings | Low-fire-risk storage
Moderate-fire-risk storage | H1
H2 |
| Storage facilities | Wholesale (see storage buildings)
Offices, limited to quantity
For cotton/jute/ paper/textile | H
Non-separated use
J |
| Stores | See definition | F |
| Students' halls of
residence | For children
For adults | C
A |
| Studios | Music, dancing, or theatrical
Radio (see radio studio)
Television, with spectator
Television, without spectator | I
MIXED (I, E or G)
MIXED (depending
on nature of material
and process
involved) |
| Sugar | Production and Refining | J |
| Super market | See mercantile | F |
| Swimming pools | Commercial | I |
| | Non-Commercial (See clubs) | I |
| |
**T** | |
| Table tennis halls | See assembly | I |
| Tailor shops, custom | | F |
| Tanning (See leather
or fur) | | J |
| Tapestries manufacture | | G |
| Tar products
manufacture | | G |
| Taxidermist shops | | F |
| Telegraph offices | | E |
| Telephone exchanges
or other communications
equipment structures | | E |
| Television | Repair shops
Stores (See appliances)
Studios (see television studios)
Towers, non-accessory | F
F
M |
| Television station | See business | MIXED (E3 with
other Occupancies
according to detail
requirement) |
| Temple | See prayer hall | |
| Tennis courts, indoor | | I |
| Terminal facilities at
river crossings for
access to electric, gas,
or steam lines | | G |
| Test laboratory | involving low hazard material | E |
| Textiles | Bleaching (see industrial)
Products manufacture (see industrial)
Spinning, weaving, manufacturing,
dyeing, printing, knit goods, yarn,
thread, or cordage (see industrial) | G
G
G |
| Textile industries and
jute mills | including canvas, cotton cloth,
bagging burlap, carpet and rags
(see industrial) | J |
| Theater | See assembly | I |
| Theaters, drive-in | (See studios) | |
| Theatrical studios | without spectator | G |
| Tile | Manufacture | G |
| Tire sales
establishments | Including installation services,
Limited to quantity
Including installation services,
unlimited quantity | F
J |
| Tobacco | Curing or manufacture, or tobacco
products manufacture
Stores (retail) | J
F |
| Toilet, public | | L |
| Toiletries manufacture | | G or J depending on
the material and
process involved |
| Tool or hardware
manufacture | See industries | G |
| Topsoil storage | See storage | H |
| Tourist cabins | See residential | A |
| Towel supply
establishments | | F |
| Toys | Manufacture
Stores | G
F |
| Trade or other schools
for adults | Limited as to objectionable effects
(see educational)
Unlimited (see educational) | B
B |
| Trade expositions | Limited as to rated capacity
Unlimited | I
I |
| Trailer, truck, bus | Manufacture, including parts
Repairs, body
Sales open or enclosed | G or J depending on
the material and
process involved
G or J depending on
the material and
process involved
F |
| | Showrooms, with no repair services | F |
| Training center | lecture based, limited to quantity
(see educational facilities)
vocational or demonstrative
(see educational facilities) | E1 or B2
B2 |
| Transit substations | Small or medium size
Large | G
G |
| Transport terminal | Small or medium size
Large | MIXED depending
on nature of use
MIXED depending
on nature of use |
| Travel agency | (see business) | E |
| Travel bureaus | (see business) | E |
| Truck | Manufacture (including parts)
or engine rebuilding | G or J depending on
the material and
process involved |
| | Repairs, body | G |
| | Repairs, except body repairs
Sales open or enclosed | G
F |
| | Showrooms, with no repair services | F |
| | Trucking terminals or motor freight
stations, Limited as to lot area
Trucking terminals or motor freight
stations, Unlimited | K1
K1 |
| Tutorial homes | More than six occupants
(see educational) | B |
| Turpentine
manufacture | | J |
| Typewriter stores | | F |
| Typewriter or other
small business machine
repair shops | | F |
| Typography | (See printing) | |
| | **U** | |
| Umbrellas | Manufacture | G |
| | Repair shops | F |
| University | See educational facilities | B2 |
| Upholstery | Manufacturing | J |
| | Bulk, including shops not dealing
directly with consumers
Shops dealing directly with
consumers, retail | J
F |
| Utility | | L |
| **Use or Occupancy** | **Brief Description** | **Occupancy** |
| | | **Class/Sub-class** |
| | **V** | |
| Variety stores | Limited as to floor area
Unlimited | F
F |
| Varnish manufacture | | J |
| Vehicles | Dead storage of motor
Manufacture, children's
Storage, commercial or public utility,
open or enclosed | H
G
K |
| Venetian blind,
window shade, or
awning | Custom shops, limited as to floor area
Manufacture, with no limitation on
production or on floor area | F
J or G depending
upon nature of
materials involved |
| Ventilating
contractors | (See contractors' establishments) | F |
| Ventilating equipment
showrooms | Without repair facilities | F |
| Video games shop | | F |
| Vihara, Buddhist | with occasional or regular assembly | mixed use |
| | **W** | |
| Wallpaper stores | Limited to quantity | H |
| Warehouses | | H or J (depending
on the nature of
material stored) |
| Watch or clock stores
or repair shops | | F |
| Watch making | | G |
| Waterfront shipping | | Not applicable |
| Water pumping stations | At distributor's end
At consumer's end | G
L |
| Water tank tower | | M |
| Wax products
manufacture | | G |
| Weaving, hand | Up to six hand-weaving machines
More than six hand-weaving
machines | Non- separated use
to main Occupancy
G |
| Wedding chapels | See assembly | I |
| Welding shops | Arc welding only
Gas welding within exempted
quantity | G
G or J depending
upon the quantity of
material and process |
| Welfare centers | | |
| Wholesale
establishments | | H or J depending
upon the nature of
material |
| Wholesale offices or
showrooms, with
storage restricted to
samples | | E |
| Window manufacture | | G |
| Window shades | Custom shops, limited as to floor area | F |
| | Manufacture, without limitation on
production or on floor area | G |
| Wood | Bulk processing or woodworking
Distillation | G
G |
| | Products manufacture | G |
| | Pulp or fibre, reduction or processing,
including paper mill operations | G |
| | Sales, open or enclosed, Limited as to
lot area
Unlimited (See lumber yards)
Woodworking shops, custom | F
F
J or G depending
upon nature of
materials involved |
| Wool scouring or pulling | | G |
| Workshops | With hot-works | J |
| | Without hot-works | G |
| | **X** | |
| X-ray facilities | See radiological facilities | |
| | **Y** | |
| Yard | | Not applicable |
| Yard, ship | See ship or boat building or repair yards | |
| Yarn, manufacturing | | G or J depending on
the quantity (see
Table 3.2.5) |
| | **Z** | |
| Zoo structures | | M |
* \*\* The occupancy classification for any project, not included in this list, shall be determined through the following process:
* i. The functional requirements of the unidentified occupancy shall be compared with the Occupancy use type, classification, sub-classification categories and descriptions to match with the given occupancies to find the most similar Occupancy,
* ii. If process (i) fails to determine the Occupancy, the project will be referred to the Board of Appeal constituted as per directives of Part 2 Chapter 2. The Board of Appeal shall determine the Occupancy, and
* iii. The decision of Board of Appeal shall be considered as an explanatory material of this Code and shall be added as addendum to this Code. For any future projects of similar nature this addendum will suffice and need not be referred to the Board of Appeal again.
# Chapter 3: Classification of Building Construction Types Based on Fire Resistance
Source: https://docs.sayed.app/bnbc/part-3-general-building-requirements/chapter-3-classification-of-building-construction-types-based-on-fire-resistance
## **3.1 General**
### **3.1.1 Classification by Type of Construction**
For the purpose of this Code, every room or space of a building or a building itself hereafter altered or erected shall be classified in one specific type of construction as grouped as follows:
GROUP I: Noncombustible, subdivision
Type I-A: 4 hour fire protected Type I-B: 3 hour fire protected Type I-C: 2 hour fire protected Type I-D: 1 hour fire protected Type I-E: Unprotected GROUP II: Combustible subdivision
Type II-A: Heavy timber Type II-B: Protected wood joist Type II-C: Unprotected wood joist Type II-D: Protected wood frame Type II-E: Unprotected wood frame
The fire resistance ratings of various types of construction for structural and nonstructural members are specified in Tables 3.3.1 (a) and (b). For hazardous Occupancies involving an exceptionally high degree of fire risk or an exceptionally high concentration of combustible or flammable content, the Authority may increase the requirement of Table 3.3.1 (a).
Buildings having a height of more than 33 m shall be constructed with non-combustible materials.
The fire resistance ratings of various building components shall conform to ASTM standards.
No building or portion thereof shall be designated a given construction type unless it fully conforms to the minimum requirements for that Construction type.
When a type of construction is utilized which is superior than the type of construction required by this Code, there shall be no requirement to upgrade the rest of the construction to comply to that higher type of construction and the designated construction type shall be that of the lesser classification, unless all of the requirements for the higher classification are met.
### **3.1.2 Group I: Non-Combustible Construction**
Buildings or portion thereof in Non-combustible Construction Group I are those in which the walls, exit-ways, shafts, structural members, floors, and roofs are constructed of non-combustible materials and assemblies having fire-resistance ratings specified in Table 3.3.1 (a). The Non-combustible group consists of Construction Type I-A, I-B, I-C, I-D and I-E.
#### 3.1.2.1 Construction Type I-A
This construction type includes buildings in which the bearing walls and other major structural elements are generally of four-hour-fire-resistance rating.
#### 3.1.2.2 Construction Type I-B
This construction type includes buildings in which the bearing walls and other major structural elements are generally of three-hour-fire-resistance rating.
#### 3.1.2.3 Construction Type I-C
This construction type includes buildings in which the bearing walls and other major structural elements are generally of two-hour-fire-resistance rating.
#### 3.1.2.4 Construction Type I-D
This construction type includes buildings in which the bearing walls and other major structural elements are generally of one-hour-fire-resistance rating.
#### 3.1.2.5 Construction Type I-E
This construction type includes buildings in which the bearing walls and other major structural elements generally have no fire-resistance rating.
### **3.1.3 Group II: Combustible Construction**
Buildings or portion thereof in Combustible Construction Group II are those in which the walls, exit-ways, shafts, structural members, floors, and roofs are constructed wholly or partly of combustible materials having fire-resistance ratings specified in Table 3.3.1 (b). The Non-combustible group consists of Construction Type II-A, II-B, II-C, II-D and II-E.
#### 3.1.3.1 Construction Type II-A
This Construction type includes heavy timber construction in which fire-resistance is attained by
* (a) Limiting the minimum sizes of wood structural members and the minimum thickness and composition of wood floors and roofs;
* (b) Avoiding concealed spaces under floors and roofs or by providing fire-stopping protection for these spaces; and
* (c) Using fastening, construction details, and adhesives for structural members as required by this Chapter and Part 4.
* (d) The minimum dimensions for framing members shall be prescribed in this Chapter and Part 4, except that members are protected to provide a fireresistance rating of at least one hour need not comply with this requirement.
#### 3.1.3.2 Construction Type II-B
This Construction type includes buildings and portion thereof in which
* (a) Exterior walls, fire walls, exit-ways, and shaft enclosures are of non-combustible materials having the required fire-resistance ratings; and
* (b) The floors, roofs and interior framing are wholly or partly of wood of smaller dimensions than required for type II-A construction, or are of other combustible or non-combustible materials, having the required fire-resistance rating.
**Table 3.3.1 (a): Fire Rating for Construction Group I: Non-Combustible**
| Exterior wall with Fire Separation Distance of | Construction Element | I-A Ratings (hrs) | I-A Exterior Openinga,b | I-B Ratings (hrs) | I-B Exterior Openinga,b | I-C Ratings (hrs) | I-C Exterior Openinga,b | I-D Ratings (hrs) | I-D Exterior Openinga,b | I-E Ratings (hrs) | I-E Exterior Openinga,b |
| ------------------------------------------------ | ----------------------- | ----------------- | ---------------------------------- | ----------------- | ---------------------------------- | ----------------- | ---------------------------------- | ----------------- | ---------------------------------- | ----------------- | ---------------------------------- |
| 0.9m or less | Bearing | 4 | N.P | 3 | N.P | 2 | N.P | 2 | N.P | 2 | N.P |
| 0.9m or less | Non-bearingf | 2 | N.P | 2 | N.P | 2 | N.P | 2 | N.P | 2 | N.P |
| More than 0.9m but less than 4.5m | Bearing | 4 | as per provisions of this Code | 3 | as per provisions of this Code | 2 | as per provisions of this Code | 2 | as per provisions of this Code | 2 | as per provisions of this Code |
| More than 0.9m but less than 4.5m | Non-bearingf | 2 | as per provisions of this Code | 2 | as per provisions of this Code | 2 | as per provisions of this Code | 2 | as per provisions of this Code | 2 | as per provisions of this Code |
| 4.5m or more but less than 9.0m | Bearing | 4 | as per provisions of this Code | 3 | as per provisions of this Code | 2 | as per provisions of this Code | 1 | as per provisions of this Code | 0 | as per provisions of this Code |
| 4.5m or more but less than 9.0m | Non-bearingf | 1½ | as per provisions of this Code | 1½ | as per provisions of this Code | 1 | as per provisions of this Code | 1 | as per provisions of this Code | 0 | as per provisions of this Code |
| Shafts (other than exits) and elevator hoistways | — | 2 | — | 2 | — | 2 | — | 2 | — | 2 | — |
| Fire separation wall and party wall | — | 4 | — | 2 | — | 2 | — | 2 | — | 2 | — |
| Access corridor leading to fire exits | — | 1 | — | 1 | — | 1 | — | 1 | — | 1 | — |
N.P = Not Permitted; N.L = No Limit
**Table 3.3.1 (b): Fire Rating for Construction Group II: Combustible**
| Exterior wall with Fire Separation Distance of | Construction Element | II-A Ratings (hrs) | II-A Exterior Openinga,b | II-B Ratings (hrs) | II-B Exterior Openinga,b | II-C Ratings (hrs) | II-C Exterior Openinga,b | II-D Ratings (hrs) | II-D Exterior Openinga,b | II-E Ratings (hrs) | II-E Exterior Openinga,b |
| ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------- | ------------------------------ | ----------------------------------- | ------------------ | ----------------------------------- | ------------------ | ----------------------------------- | ------------------ | ----------------------------------- | ------------------ | ----------------------------------- |
| 0.9m or less | Bearing | 2 | N.P | 2 | N.P | 2 | N.P | 2 | N.P | 2 | N.P |
| 0.9m or less | Non-bearingf | 2 | N.P | 2 | N.P | 2 | N.P | 2 | N.P | 2 | N.P |
| More than 0.9m but less than 4.5m | Bearing | 2 | as per provisions of this Code | 2 | as per provisions of this Code | 2 | as per provisions of this Code | 1 | as per provisions of this Code | 1 | as per provisions of this Code |
| More than 0.9m but less than 4.5m | Non-bearingf | 2 | as per provisions of this Code | 2 | as per provisions of this Code | 2 | as per provisions of this Code | 1 | as per provisions of this Code | 1 | as per provisions of this Code |
| 4.5m or more but less than 9.0m | Bearing | 2 | as per provisions of this Code | 2 | as per provisions of this Code | 2 | as per provisions of this Code | 1 | as per provisions of this Code | 0 | as per provisions of this Code |
| 4.5m or more but less than 9.0m | Non-bearingf | 2 | as per provisions of this Code | 2 | as per provisions of this Code | 2 | as per provisions of this Code | 1 | as per provisions of this Code | 0 | as per provisions of this Code |
| 9.0m or more | Bearing | 1 | N.L | 1½ | N.L | 1½ | N.L | 1 | N.L | 0 | N.L |
| 9.0m or more | Non-bearingf | 0 | N.L | 0 | N.L | 0 | N.L | 0 | N.L | 0 | N.L |
| Interior bearing walls and bearing partitions | — | 2 | — | 1 | — | 0 | — | 1 | — | 0 | — |
| Enclosure of vertical exitse, exit passageways, hoistways and shafts | — | 2 | — | 2 | — | 1i | — | 1i | — | 1 | — |
| Fire divisions and fire barrier — Walls or partitions or ceiling slab | See Table 3.2.1 and provisions of this Code | — | — | — | — | — | — | — | — | — | — |
| Columnsk, girders, trusses (other than roof trusses) and framing — Supporting one floor | — | as per provisions of this Code | — | 1 | — | 0 or 1j | — | 1 | — | 0 | — |
| Columnsk, girders, trusses (other than roof trusses) and framing — Supporting more than one floor | — | as per provisions of this Code | — | 1 | — | 0 or 1j | — | 1 | — | 0 | — |
| Structural members supporting walls | — | 3 | — | 2½ | — | 2 | — | 1½ | — | 1 | — |
| Floor construction including beams | — | as per provisions of this Code | — | 1 | — | 0 or 1j | — | 1 | — | 0 | — |
| Roof construction, including beams, trusses and framing including arches, domes, shells, cable supported roofs and roof decksh — 4.5m or less in height above floor to lowest member of ceiling | — | as per provisions of this Code | — | 3/4 | — | 0 | — | 3/4 | — | 0 | — |
| Roof construction, including beams, trusses and framing including arches, domes, shells, cable supported roofs and roof decksh — 4.5m to 6m in height above floor to lowest member of ceiling | — | as per provisions of this Code | — | 3/4 | — | 0 | — | 3/4 | — | 0 | — |
| Roof construction, including beams, trusses and framing including arches, domes, shells, cable supported roofs and roof decksh — 6m or more in height above floor to lowest member of ceiling | — | as per provisions of this Code | — | 3/4 | — | 0 | — | 3/4 | — | 0 | — |
| Shafts (other than exits) and elevator hoistways | — | 2 | — | 2 | — | 2 | — | 2 | — | 2 | — |
| Fire separation wall and party wall | — | 4 | — | 2 | — | 2 | — | 2 | — | 2 | — |
| Access corridor leading to fire exits | — | 1 | — | 1 | — | 1 | — | 1 | — | 1 | — |
N.P = Not Permitted; N.L = No Limit
**Notes:**
* a Requirements of protected exterior openings shall not apply to religious assembly. \[Protected openings within an exterior separation of 0.9m or less are permitted for buildings classified in Occupancy Groups A provided, however said openings do not exceed in total area of 25% of the façade of the storey in which they are located. The openings however, may not be credited towards meeting any of the mandatory natural light and ventilation as per provisions of this Code. Protection of openings with an exterior separation of 0.9 m to 9 m shall not be required for A-1, A-2 and A-3 Occupancy groups] or to buildings classified in Occupancy groups J, G and H additional requirements for exterior walls and exterior wall openings as per provisions of this Code.
* b Upon special application, the area development authorities may permit exterior wall openings to be constructed in excess of the permitted area established by this Table if such openings at the time of their construction are located at least 18m in a direct line from any neighboring building except as otherwise permitted in footnote f. Such additional openings may not however be credited toward meeting any of the mandatory natural light and ventilation requirements of Sec 1.19 Part 3 of this Code. If any neighboring building is later altered or constructed to come within the above distance limitation, the affected exterior openings shall immediately be closed with construction meeting the fire-resistance rating requirements for exterior wall construction of the building in which they are located.
* c Applies to occupancy groups J, G and H
* d Applies to occupancy groups J, G and H
* e See Provisions of this Code for additional impact resistance requirements applicable to certain stair enclosures and for certain exceptions to stair enclosure requirements.
* f When two or more buildings are constructed on the Plot and the combined floor area of the buildings does not exceed the limits established by this Code for any of the buildings, not fire-resistance rating shall be required for non-bearing portions of the exterior walls of those buildings facing each other, and there shall be no limitation on the permitted amount of exterior openings.
* g Fire retardant treated wood complying with the requirements of this Code may be used.
* h Tabulated ratings apply to buildings over one storey in height. In one storey building, roof construction may be of material having zero hour fire-resistance rating.
* i Materials which are not non-combustible as defined in this Code may be used in nonbearing construction elements as per provisions for this Code.
* 1 Materials having a structural base of non-combustible materials as defined in this Code, and having a surface not over 3.2 mm thick which when tested in accordance with the provisions of this Code has a flame spread rating not higher than 50 (fifty).
* 2 Materials which when tested in accordance with the provisions of this Code have a surface flame spread rating not higher than twenty five without evidence of continued progressive combustion, and which are of such composition that surface which would be exposed by cutting through the material in any way would not have a flame spread ratings higher than twenty-five without evidence of continued progressive combustion.
* j Applies to the construction of the street floor and all construction below the level of the street floor in building or spaces classified in occupancy group A-3 except where the space below the street floor does not exceed five feet in height.
* k Columns supproting the roof of a one-story building shall have the same fireresistance rating as required for a column supporting one floor in a building of the same construction class.
* l Members supporting loads of not more than two floors or one floor and a roof need not have a fire-resistance rating greater than the floor construction fire-resistance requirement in buildings classified in occupancy groups B, C and A-3, not including unsprinklered spaces of other occupancies, and in fully sprinklered buildings in occupancy groups E and A-5.
#### 3.1.3.3 Construction Type II-C
This Construction type includes buildings and portion thereof in which
* (a) Exterior walls, fire walls, exit ways, and shaft enclosures are of noncombustible materials having the required fire-resistance ratings; and
* (b) The floors, roofs and interior framing are wholly or partly of wood of smaller dimensions than required for type II-A construction, or are of other combustible or non-combustible materials, having no required fire-resistance rating.
#### 3.1.3.4 Construction Type II-D
This Construction type includes buildings and portion thereof in which exterior walls, bearing walls, floors, roofs, and interior framings are generally of wood or other combustible materials having the required fire-resistance ratings.
#### 3.1.3.5 Construction Type II-E
This Construction type includes buildings and portion thereof in which
* (a) The exterior walls are generally of wood or other combustible materials having the required fire-resistance ratings, and
* (b) In which the bearing walls, floors, roofs, and interior framing are of wood or other combustible materials, generally having no fire-resistance ratings.
### **3.1.4 Separated Occupancy and Construction**
When two or more occupancies accommodated in a building, each such occupancy shall be separated according to the provisions specified in Sec 2.3 Chapter 2 Part 3 and Table 3.2.1.
When two or more types of construction used within a building, the entire building shall be subject to the most restrictive construction type and shall comply with FAR restrictions as per provisions of this Code.
However if the Occupancies within the different Types of Construction are completely separated by construction that meets the fire-resistance rating requirements for fire separation listed in Table 3.2.1 of Chapter 1 Part 3 then each Occupancy so separated may, for the purpose of this Code, be considered as separate building section.
#### 3.1.4.1 Restriction for mixed construction
In buildings of mixed construction, no structural element shall be supported by construction having a lower fire-resistance rating than that required for the element being supported.
### **3.1.5 Fire Zones**
The planning and development authority of the city, township, municipality or region where this Code is intended to be implemented shall divide the area under their jurisdiction into distinct fire zones. The basis for this zoning shall be the fire hazard inherent in the buildings and the degree of safety desired for the occupancy accommodated therein. The number of zones in an area shall depend on its size and the strategies undertaken for its development.
#### 3.1.5.1 Fire Zone 1
The following occupancy groups shall comprise this zone:
| Occupancy A: | Residential | Occupancy F: | Mercantile |
| ------------ | ---------------------- | ------------ | ------------------------------- |
| Occupancy B: | Educational | Occupancy H: | Livestock Storage
Building |
| Occupancy C: | Institutional for Care | Occupancy I: | Assembly |
| Occupancy D: | Health Care | Occupancy K: | K1 and K2 Parking |
| Occupancy E: | Offices | Occupancy M: | Miscellaneous Buildings |
#### 3.1.5.2 Fire Zone 2
The following occupancy groups shall comprise this zone:
Occupancy G: Industrial Buildings Occupancy H: Storage Buildings Occupancy K: K3 Parking
#### 3.1.5.3 Fire Zone 3
The only occupancy falling in this zone shall be Occupancy J, Hazardous Buildings.
#### 3.1.5.4 Change in Fire Zone Boundaries
The demarcations of fire zones may be changed or new occupancies may be included in any fire zone through the same procedure as for promulgating new rules or ordinances or both.
#### 3.1.5.5 Buildings on overlapping fire zones
Buildings falling on more than one fire zones shall be considered to be situated on the zone in which the major portion of the building falls. If a building is divided equally between more than one fire zones, it shall be considered as falling in the fire zone having more hazardous occupancy buildings.
#### 3.1.5.6 Restrictions on temporary constructions
Permission may be granted by the Authority for temporary constructions only in fire zones 1 and 2 and not in fire zone 3. Such temporary constructions shall adhere to the conditions of the permission and shall be demolished and removed completely after the expiry of the duration of the permission unless it is extended by the Authority or a new permission is obtained.
### **3.1.6 Permissible Types of Construction for Various Occupancies**
#### 3.1.6.1 New buildings
Types of constructions permitted for various buildings on the basis of fire zones are specified in Table 3.2.4.
#### 3.1.6.2 Existing buildings
Existing buildings in any fire zone need not comply with the provision of this Code for type of construction unless they are altered or in the opinion of the Authority they constitute a hazard to the safety to the occupants of the buildings or the adjacent properties.
### **3.1.7 Exterior Walls**
The fire resistance rating of the exterior walls shall conform to the provisions set forth in Table 3.2.2 and Sec 3.2.3.
### **3.1.8 Basement Floor**
Basement floor of a building shall be enclosed with a one hour fire resistive construction. Doors in such constructions shall be made of noncombustible materials.
### **3.1.9 Restricting Horizontal and Vertical Spread of Fire**
Generally walls restrict horizontal movement and slabs restrict vertical movement of fire.
#### 3.1.9.1 Interior or barrier or enclosure wall
Propagation of fire, smoke, gas or fume through the openings or shafts or penetrations of fire resistive floors and walls shall be restricted by sealing with an approved material which shall have a fire resistance rating at least equal to that of the floor-wall assembly. The sealing material shall be capable of preventing passage of flame and hot gases sufficient to ignite cotton waste when tested in accordance with ASTM E119.
#### 3.1.9.2 Exterior walls
Permitted unprotected openings in the exterior wall in two consecutive floors lying within 1.5 m laterally or vertically shall be separated with flame barriers as similar as sunshades or cornices or projected wall at least 750 mm from the external face of the exterior wall. The flame barrier shall have a fire resistance rating of not less than three-fourths hour.
### **3.1.10 Exceptions to Fire Resistance Requirements**
The provisions of this Section are exceptions to the occupation separation requirements of Table 3.2.1.
#### 3.1.10.1 Fixed partitions
* (a) Stores and Offices: In such cases where offices, stores and similar places occupied by one tenant are separated by non-load bearing walls that do not form a corridor serving an occupant load, the partition walls may be constructed of any one of the following:
* (i) Noncombustible materials;
* (ii) Fire retardant treated wood;
* (iii) One hour fire resistive construction;
* (iv) Wood panels or similar light construction up to three fourths the height of the room in which placed; and
* (v) Wood panels or similar light construction more than three-fourths the height of the room in which placed with not less than upper one fourth of the partition constructed of glass.
* (b) Hotels and Apartments: In such cases where non-load bearing walls act as interior partitions in individual dwelling units in apartment houses and guest rooms or suites in hotels when such dwelling units, guest rooms or suites are separated from each other and from corridors by not less than one-hour fire-resistive construction, the partition walls may be constructed of any one of the following:
* (i) Noncombustible materials of fire retardant treated wood in buildings of any type of construction; or
* (ii) Combustible framing with noncombustible materials applied to the framing in buildings of Type II construction.
* (c) Folding, Portable or Movable Partitions: Folding, portable or movable partitions need not have a fire resistance rating if the following conditions are satisfied:
* (i) Required exits are not blocked without providing alternative conforming exits;
* (ii) Tracks, guides or other approved methods are used to restrict their locations; and
* (iii) Flammability shall be limited to materials having a flame-spread classification as set forth in Table 3.3.2 for rooms or areas.
**Table 3.3.2: Flame Spread Classification**
| **Class** | **Flame Spread Index** |
| --------- | ---------------------- |
| I | 0-25 |
| II | 26-75 |
| III | 76-200 |
* (d) Walls Fronting on Streets or Yards: For walls fronting on a street or yard having a width of at least 12 m, certain elements of the wall may be constructed as follows regardless of their fire-resistive requirements:
* (i) Bulkheads below show windows, show window frames, aprons and show-cases may be of combustible materials provided the height of such construction does not exceed 5 m above grade.
* (ii) Wood veneer of boards not less than 25 mm in nominal thickness or exterior type panels not less than 10 mm in nominal thickness may be used in walls provided:
* the veneer does not extend beyond 5 m above grade; and
* The veneer is placed either directly against noncombustible surface or furred out from such surfaces not to exceed 40 mm with all concealed spaces fire blocked.
* (e) Trim: Wood may be used to construct trim, picture moulds, chair rails, baseboards, handrails and show window backing. If there is no requirement for using fire protected construction, unprotected wood doors and windows may be used.
* (f) Loading Platform: Noncombustible construction of heavy timber may be used for exterior loading platforms with wood floors not less than 50 mm in nominal thickness. Such wood construction shall not be carried through the exterior walls.
* (g) Insulating Boards: Combustible finished boards may be used under finished flooring.
### **3.1.11 Shaft Enclosures**
#### 3.1.11.1 General
Construction requirement for shafts through floors shall conform to the provisions of Tables 3.3.1 (a) and (b).
#### 3.1.11.2 Extent of enclosures
Shaft enclosures shall extend from the lowest floor opening through successive floor openings and shall be enclosed at the top and bottom.
Exceptions:
* (a) Shafts need not be enclosed at the top if it extends through or to the underside of the roof sheathing, deck or slab.
* (b) Noncombustible ducts carrying vapours, dusts or combustion products may penetrate the enclosure at the bottom.
* (c) Shafts need not be enclosed at the bottom when protected by fire dampers conforming to "Test Methods for Fire Dampers and Ceiling Dampers", installed at the lowest floor level within the shaft enclosure.
#### 3.1.11.3 Special provision
In groups other than Occupancies C and D, openings which penetrate only one floor and are not connected with any other floor or basement and which are not concealed within building construction assemblies need not be enclosed.
#### 3.1.11.4 Protection of openings
Openings in shaft enclosures shall be protected with a self-closing or an automaticclosing fire assembly having a fire resistance rating of
* (a) one hour for one hour fire resistive walls
* (b) one and one-half hours for two hour fire resistive walls
#### 3.1.11.5 Rubbish and linen chute termination rooms:
Rubbish and linen chute shall terminate in rooms separate from the remaining of the building having the same fire resistance as required for shafts in Table 3.3.1 (a) and (b) but not less than one hour.
### **3.1.12 Expansion and Contraction Joints**
Expansion and contraction joints provided to accommodate expansion, contraction, wind or seismic movement shall be protected with an approved material having the same degree of fire resistance as that of the wall or floor in which it is installed.
### **3.1.13 Weather Protection**
#### 3.1.13.1 Weather resistive barrier
All weather exposed surfaces shall have a weather barrier to protect the interior wall from damping. Such weather barriers shall have a fire resistance rating of at least equal to that of the wall or floor on which it is applied. Weather resistive barrier need not be used in the following cases:
* (i) When exterior covering is of approved waterproof panels
* (ii) In back plastered construction
* (iii) When there is no human occupancy
* (iv) Over water repellent panel sheathing
* (v) Under approved paper backed metal or wire fabric lath
* (vi) Behind lath and Portland cement plaster applied to the underside of roof and eave projections
#### 3.1.13.2 Flashing and counter flashing
Exterior openings exposed to the weather shall be flashed to make them weather proof. There shall be copings with all parapets. Corrosion resistant metals shall be used for flashing, counter flashing and coping.
#### 3.1.13.3 Waterproofing weather-exposed areas
Waterproofing shall be applied to exposed surfaces like balconies, external stairways and landings.
#### 3.1.13.4 Damp-proofing foundation walls
Outside of foundation walls enclosing a basement floor below finished grade shall be damp-proofed from outside.
### **3.1.14 Members Carrying Walls**
All members carrying masonry or concrete walls shall be fire protected as specified in Table 3.3.1 (a) and (b).
### **3.1.15 Parapets**
Parapets constructed on exterior wall of a building shall have the same degree of fire resistance required for the wall upon which they are erected and there shall be noncombustible faces on the side adjacent to the roof surface for the uppermost 405 mm including counter flashing and coping materials. The height of the parapet shall be at least 750 mm from the upper surface of the roof.
### **3.1.16 Projections**
Sunshades, cornices, projected balconies and overhanging beyond walls of Type I construction shall be of noncombustible materials. Projections from walls of Type II may be of combustible or noncombustible materials.
### **3.1.17 Guards and Stoppers**
#### 3.1.17.1 Guards
Guards or Guardrails shall be provided to protect edges of floor, roof, roof openings, stairways, landings and ramps, balconies or terraces and certain wall, which are elevated more than 750 mm above the grade and as per provisions of this Code.
#### 3.1.17.2 Stoppers
Stopper shall be provided in open parking garages located more than 450 mm above the adjacent grade or back to back parking stall. The height of the stopper shall be at least 300 mm and it shall be positioned at outer edges of a car parking stall.
### **3.1.18 Insulation**
The provisions of this Section are applicable to thermal and acoustical insulations located on or within floor-ceiling and roof ceiling assemblies, crawl spaces, walls, partitions and insulation on pipes and tubing.
Materials used for such insulation and covering shall have a flame spread rating not more than 25 and a smoke density not more than 450.
### **3.1.19 Atrium**
#### 3.1.19.1 General
Atrium may be provided in all groups other than Occupancy J (Hazardous Buildings). Such atrium shall have a minimum opening and are as specified in Table 3.3.3. A vertical opening serving as other than an exit enclosure connecting only two adjacent stories shall be permitted to be open to one of the two stories.
**Table 3.3.3: Atrium Opening and Area**
| **Height in Stories** | **Minimum Clear Opening¹ (m)** | **Minimum Area (m****2****)** |
| ----------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------ | ---------------------------------------- |
| 2-4 | 6 | 40 |
| 5-7 | 9 | 90 |
| 8 or more | 12 | 160 |
| 1 The specified dimensions are the diameters of inscribed circles whose centers fall on a common axis for the full height of the atrium. | | |
#### 3.1.19.2 Smoke control system
A mechanically operated air-handling system shall be installed to exhaust the smoke either entering or developed within the atrium.
* (a) Exhaust Openings: The location of the exhaust openings shall be in the ceiling or in a smoke trap area immediately adjacent to the ceiling of the atrium above the top of the highest portion of door openings into the atrium.
* (b) Supply Openings: Supply openings designed for a minimum of 50 percent of the exhaust volume shall be located at the lowest level of the atrium. Supply air may be introduced by gravity provided the height of the atrium is not more than 18 m and smoke control is established. For atria having height greater than 18 m, supply air shall be introduced mechanically from the floor of the atrium and directed vertically toward the exhaust outlets. Supplemental air supply may be introduced at upper levels in atrium over six storeys in height or when tenant spaces above the second storey are open to the atrium.
* (c) Automatic Operation: The smoke control system for the atrium shall be activated automatically by the automatic sprinkler system or smoke detectors installed within the atrium or areas open to the atrium.
* (d) Manual Operation: The smoke control system shall also be manually operable for use by the fire department. The smoke control system may be separate from or integrated with other air handling systems. Air handling systems interfering with the smoke control system shall be shut down automatically when the smoke control system is activated.
* (e) Smoke Detector Location: Smoke detectors which will automatically operate the smoke control system of the atrium shall be accessible for maintenance, testing and servicing. Their locations shall be as follows:
* (i) At the atrium ceiling, spaced in accordance with the manufacturer's instructions.
* (ii) On the underside of projections into the atrium, in accordance with the manufacturer's instructions.
* (iii) Around the perimeter of the atrium opening on all floors open to the atrium. These detectors shall be spaced no more than 9 m on centre and shall be located within 5 m of the atrium opening.
* (iv) If projected beam type smoke detectors are used, they shall be installed in accordance with manufacturer's instructions.
* (f) Enclosure of Atrium: Atria shall be separated from the adjacent spaces with fire resistive separation of at least one hour.
Fire windows may be provided in fixed glazed openings when the window has a fire resistive rating of at least three-fourths hour and the area of the opening does not exceed 25 percent of the wall common to the atrium and the room into which the opening is provided.
### **3.1.20 Mezzanine Floors**
Construction of a mezzanine floor shall conform to the requirements of the main floor in which it is constructed but the fire resistance rating need not exceed one hour for unenclosed mezzanines.
# Chapter 4: Energy Efficiency and Sustainability
Source: https://docs.sayed.app/bnbc/part-3-general-building-requirements/chapter-4-energy-efficiency-and-sustainability
**PART III Chapter 4 Energy Efficiency and Sustainability**
## **4.1 Scope**
The purpose of including this Chapter in the Code is to enhance the design and construction of buildings through the use of building concepts having a positive environmental impact and encourage sustainable construction practices, allowing efficiency and conservation of energy, water and building materials, and to promote resource efficiency.
In addition to the clauses stipulated here, all Codes and standards relevant to a building occupancy as set forth in other Sections of this Code will be applicable during implementation.
Design and drawings will be submitted to indicate the location, nature and scope of the proposed energy efficient/sustainable feature. These shall indicate compliance to the provisions of this Code, and will be supplied by the relevant design professionals, e.g. electrical engineers, mechanical engineers, plumbing engineers, etc., supporting architectural drawings.
### **4.1.1 Rationale for Sustainable/Green Buildings**
Climate change is an established phenomenon affecting the environment globally and it is recognized that buildings and the built environment play a vital role in the process, impacting on the natural environment and the quality of life. Sustainable development concepts and approaches applied to the design, construction and operation of buildings or to any built environment can enhance both the economic and environmental benefits of the community in Bangladesh and around the world. Energy efficiency and sustainability is not an individual issue rather an integrated and inseparable part of the building design and construction process. The benefits of sustainable design principles include resource and energy efficiency, healthy buildings and materials, ecologically and socially sensitive land use and strengthened local economics and the communities, objectives vital for future development of Bangladesh.
## **4.2 Definitions**
| DAYLIGHT ZONE | An area with a depth of 5m parallel to any glazed external
wall. |
| -------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| EMERGENCY
LIGHTING | Lighting used for emergency spaces and functions, e.g. in fire
stairs, for egress path signage. |
| GREY WATER | Waste watergenerated from wash hand basins, showers and
baths, Grey water often excludes discharge from laundry,
dishwashers and kitchen sinks due to the high nutrient levels. |
| | It
differs
from
the
discharge
of
WC's
which
is
designatedsewage or black waterto indicate it containshuman
waste. |
| REGULARLY
OCCUPIED SPACE | All the main areas in the buildings that are used on a frequent
basis, such as living rooms, bedrooms, classrooms, lobbies,
meeting rooms, hall rooms and office spaces. Service spaces
like toilets, bathrooms, corridors and stores will not be
considered as frequently occupied areas. |
| WINDOW TO | The window-to-wall ratio of a building is the percentage of its |
| WALL RATIO OF
BUILDING
(WWRB) | facade taken up by light-transmitting glazing surfaces,
including windows and translucent surfaces such as glass
bricks. It does not include glass surfaces used ornamentally or
as cladding, which do not provide transparency to the interior.
Only facade surfaces are counted in the ratio, and not roof
surfaces. |
| LIGHTING POWER
DENSITY (LPD) | Average total lighting power installed divided by the total
occupied area. |
| SHADING
COEFFICIENT (SC) | The ratio of solar heat gain at normal incidence through
glazing to that occurring through 1/8 inch thick clear, double-
strength glass. Shading coefficient, as used herein, does not
include interior, exterior, or integral shading devices. |
| SOLAR HEAT GAIN
COEFFICIENT
(SHGC) | An indicator of glazing performance is the amount of heat
admitted through the glass vis-à-vis the total heat incident on
the glass by virtue of direct solar radiation. The unit is a
simple fraction or percentage. |
| U-VALUE
(THERMAL | Heat transmission in unit time through unit area of a material
or construction and the boundary air films, induced by unit |
| TRANSMITTANCE) | temperature difference between the environments on each side.
Units of U-value are W/m2/ok |
| VISIBLE LIGHT | Amount of light transmitted through glazing, expressed as a |
| TRANSMITTANCE
(VLT) | simple fraction or percentage |
## **4.3 Site Sustainability**
This Section deals with sites to ensure energy efficiency through passive and low energy architectural features and management of resources.
### **4.3.1 Mandatory Unpaved Area**
Fifty (50) percent of mandatory open space shall be permeable on sites of all occupancy categories. The permeable area shall not remain bare generating dust, but will have green cover or be treated with perforated paving (≥ 50%), organic mulch, charcoal, etc.
### **4.3.2 Site Drainage and Run-Off Coefficient**
Designs shall indicate site drainage considerations along with flash flooding and erosion prevention measures for sites above 1340 m2 in area. As excessive paving is largely responsible for fast water run-off and flash flooding, design shall indicate measures taken to make paving permeable. The net run-off from a site shall be a maximum of sixty (60) percent. The following method will be used for the calculations, in conjunction with Table 3.4.1:
$$
\text{Total Perviousness on Open Area of Site } (A_p) = A_1 \times C_1 + A_2 \times C_2 + \dots \quad (3.4.1)
$$
Where, $A_1$, $A_2$, etc., being the areas of various surfaces, e.g. Pavements, roads, vegetation, etc., with different run-off coefficients $C_1$, $C_2$, $C_3$ etc., shown in the Table 3.4.1.
### **4.3.3 Vegetation Plan**
For sites above three (3) acres, it is mandatory for a vegetation plan to be submitted along with the site plan and Irrigation Plan, where priority shall be given to native plants in the selection for planting.
### **4.3.4 Irrigation Plan**
#### 4.3.4.1
For sites above ten (10) acres, an irrigation plan with construction details shall be submitted with the site plan, where considerations shall include for management of rainwater.
#### 4.3.4.2
For these sites a retention pond of ≥ 3% of site area shall be provided. This shall include any existing natural water body within the site.
**Table 3.4.1: Run-Off Coefficients of Various Surfaces**
| **Surface Type** | **Run-Off Coefficient, C** |
| ------------------------------------------------ | -------------------------- |
| Roofs, conventional | 0.95 |
| Green Roofs (soil/growing medium depth ≥ 300 mm) | 0.45 |
| Concretepaving | 0.95 |
| Gravel | 0.75 |
| Brickpaving | 0.85 |
| Vegetation: | |
| 1-3% | 0.20 |
| 3-10% | 0.25 |
| >10% | 0.30 |
| Turf Slopes: | |
| 0-1% | 0.25 |
| 1-3% | 0.35 |
| 3-10% | 0.40 |
| >10% | 0.45 |
### **4.3.5 Rain Water Harvesting System**
#### 4.3.5.1
Buildings of total floor area > 4000 m2 shall have its own rain water harvesting system as discussed in Chapter 7 Part 8 and installed complying with Section 7.13 Part 8, of this Code. The reservoir capacity shall be a multiple of the area of Ground Coverage of the building and a rain collection coefficient of 0.073.
#### 4.3.5.2
The rainwater reservoir may be placed under the roof or at lower levels, including underground.
## **4.4 BUILDING ENVELOPE**
### **4.4.1 Window to Wall Ratio**
#### 4.4.1.1
For mechanically ventilated and cooled buildings of all occupancies, other than Hazardous and Storage, the Window to Wall ratio of building (WWRB), will be determined in conjunction with the glazing performance, as indicated by the Solar Heat Gain Coefficient (SHGC) or Shading Coefficient (SC) of the glass used. The relationship is given in Figure 3.4.1 and Table 3.4.2.
![Selection of glazing Solar Heat Gain Coefficient (SHGC) based on Window to Wall Ratio (WWR)]()
**Table 3.4.2: Selection of Glazing SHGC Based on WWR in Tabular Format**
| **WWR** | **SHGC** | **SC** |
| ------- | -------- | ------ |
| 10 | 0.85 | 0.98 |
| 20 | 0.6 | 0.69 |
| 30 | 0.5 | 0.57 |
| 40 | 0.4 | 0.46 |
| 50 | 0.35 | 0.4 |
| 60 | 0.33 | 0.38 |
| 70 | 0.31 | 0.36 |
| 80 | 0.3 | 0.34 |
| 90 | 0.27 | 0.31 |
#### 4.4.1.2
In all of the above cases, the Visible Light Transmittance (VLT) of the glazed element shall not be lower than thirty five (35) percent.
#### 4.4.1.3
For Air-conditioned buildings with external shading, permitted SGHC limit may be adjusted, but the increase shall not exceed values determined by Eq. 3.4.2 below:
$$
SHGC_{adj} = SHGC + A \quad (3.4.2)
$$
Where,
$SHGC_{adj}$ is the adjusted solar heat gain coefficient limit for windows with shading
$SHGC$ is the solar heat gain coefficient from Table 3.4.2
$A$ is the SHGC correction factor for the external shading as per Table 3.4.3 or Table 3.4.4: For a window with overhang and fin, the value of $A$ can be only used either from overhang or from fin.
#### 4.4.1.4
For naturally ventilated buildings, window size shall be based on Sec 4.4.2. Window Openings of this Code and shading shall be provided as per Sec 4.4.3.
#### 4.4.1.5
Window size shall under no circumstances be less than as stipulated under Part
3: Chapter 1, Section 1.17 of this Code.
**Table 3.4.3: Correction Factor against Overhang Shading Projection Factor**
| **Overhang Projection Factor** | **SHGC Correction Factor(A)** |
| ----------------------------------------------------------------------------------------------- | ----------------------------- |
| 0.0 | 0.00 |
| 0.1 | 0.05 |
| 0.2 | 0.09 |
| 0.3 | 0.14 |
| 0.4 | 0.19 |
| 0.5 | 0.24 |
| 0.6 | 0.28 |
| 0.7 | 0.33 |
| 0.8 | 0.38 |
| 0.9 | 0.43 |
| 1 or higher | 0.47 |
| Projection factor for overhang is the depth of the overhang divided by the height of the window | |
**Table 3.4.4: Correction Factor against Vertical Shading (fins) Projection Factor**
| **Vertical Shading (Fins) Projection Factor** | **SHGC Correction Factor (A)** |
| ---------------------------------------------------------------------------------------- | ------------------------------ |
| 0.0 | 0.00 |
| 0.1 | 0.04 |
| 0.2 | 0.08 |
| 0.3 | 0.12 |
| 0.4 | 0.16 |
| 0.5 | 0.20 |
| 0.6 | 0.24 |
| 0.7 | 0.28 |
| 0.8 | 0.32 |
| 0.9 | 0.36 |
| 1 or higher | 0.40 |
| Projection factor of fins is the depth/length of fin divided by the width of the window. | |
### **4.4.2 Window Openings**
Mechanically ventilated and cooled buildings of all occupancies, other than hazardous, retail and storage, shall have the provision of using natural ventilation for cooling and fresh air, in frequently occupied areas , with a fraction ≥ 4% of the floor area being specified as openable windows. Openable balcony doors can be counted in this calculation. Note if the window area defined under Sec 4.4.1 is less than openable area, then fifty (50) percent of window area should be openable.
#### 4.4.2.1
Naturally ventilated buildings of all occupancies, other than hazardous and storage, shall provide for fifty (50) percent of its window area to be openable.
#### 4.4.2.2
All the openable windows above ground should be designed with safety measures in place such as protection hand rails for child safety.
#### 4.4.2.3
Windows to any regularly occupied space on exterior walls in naturally ventilated buildings shall be shaded conforming to Sec 4.4.3.
### **4.4.3 Shading**
#### 4.4.3.1
For naturally ventilated buildings of all occupancies, horizontal sunshades shall be provided over windows on South, East and West, the depth of which shall be calculated by multiplying the window height with a factor of 0.234 (Figure 3.4.2). Horizontal louvers can be used instead of sunshades, in which case, depth of louver shall not be less than 0.234 times the gaps between the louvers (Figure 3.4.3).
#### 4.4.3.2
Vertical Shading devices shall be provided on the West, depth of which shall be calculated, by multiplying the gaps between the vertical fins, or the window width if the shades border the window width, with a factor of 0.234 (Figure 3.4.4).
Exceptions:
* (a) The above rule shall be relaxed if it can be demonstrated that shading is achieved by existing neighbouring structures.
* (b) The north side of all buildings are exempt from the above rules.
![Horizontal shade geometry showing relationship between shade depth x and window height y (x ≥ 0.234y)]()
![Horizontal louvres geometry showing relationship between louver depth x and gap between louvers y (x ≥ 0.234y)]()
![Vertical shading or louvres geometry showing relationship between fin depth x and gap or window width y (x ≥ 0.234y)]()
### **4.4.4 Roof Insulation and Green Roofing System**
#### 4.4.4.1
Fifty (50) percent of horizontal exposed roof slabs of Buildings of Occupancy B, C, D and E, shall have green roofing system, to manage water run-off from roof tops, to control internal temperatures within the top floors and to reduce the carbon footprint of the building. This shall not include any covered roof surface, e.g. solar panels, solar thermal heaters, machinery for mechanical or electrical systems, water tanks, etc. Stair loft or machine room tops will be exempt from this rule.
* (a) The roof slab design shall consider structural support of the green roof system, with growing medium of minimum 300 mm.
* (b) The design will indicate protection from dampness and provide a drainage system
#### 4.4.4.2
Horizontal roof slabs, which are not covered by green roofing system, will have roof slabs with insulation, so that the time lag and decrement factor is greater than the other floor slabs of the building.
## **4.5 Energy Efficient Building Systems**
### **4.5.1 Daylighting and Supplementary Lighting System**
#### 4.5.1.1
Window area shall not be less than 14 percent or 1/7th of the total floor area of the building.
#### 4.5.1.2
Every regularly occupied space shall contain a minimum percentage of day-lit area along the building perimeter zones, with no window less than an area of 1 m2 and will ensure the appropriate stipulations given below.
* (a) for rooms that measure less than 8 m in depth, window area shall be at least 20 percent of the area of the external wall of the room.
* (b) for rooms that measure between 8 to 14 m in depth, window area shall be at least 30 percent of the area of the external wall of the room and 35 percent of the external wall.
* (c) for rooms that measure more than 14 m in depth, window area shall be at least 35 percent of the area of the external wall of the room.
#### 4.5.1.3
For Buildings of Occupancy A5, B, C, E1 and E2, photoelectric sensors shall be connected to luminaires, to enable dimming or switching off lamps that do not require to be operated, due to the presence of adequate daylight. The photoelectric sensor shall be located approximately at half (½) the depth of day-lit zone.
#### 4.5.1.4
If occupancy sensors are installed in the daylight area, the occupancy sensor shall override the daylight sensor during non-occupancy period.
Exceptions:
* (a) Zones with special requirements are exempt from the stipulation of Sec 4.5.1.3. The designer shall justify the reason for exemption.
* (b) Hotel guest rooms are exempt.
### **4.5.2 Lighting Power Density**
#### 4.5.2.1
Lighting Power Density (LPD) of the values set in Table 3.4.5 shall be provided for the respective functions within all building occupancies, or as specified.
#### 4.5.2.2
In addition to Sec 4.5.2.1, Illumination values (Lux) as specified in Tables 8.1.5 to 8.1.14 of Part 8 of this Code shall be provided for buildings of the respective occupancies.
### **4.5.3 Occupancy Sensors**
#### 4.5.3.1
In order to limit the use of electricity in the unoccupied areas of buildings, occupancy sensors linked to lighting (except for emergency and security lighting) shall be installed in the public areas of buildings of occupancies specified in Table 3.4.6.
**Table 3.4.5: Maximum Allowable Lighting Power Density for Different Occupancies**
| **Occupancy** | **Description** | **Maximum LPD (W/m****2****)** |
| --------------- | --------------------- | ----------------------------------------- |
| E1 and E2 | Offices | 9 |
| F1 and F2 | Retail/Mercantile | 13 |
| A5 | Hotels | 9 |
| D1 | Hospitals | 11 |
| A1, A2 and A3 | Apartments/residences | 7 |
| B | Educational | 11 |
| All occupancies | Covered parking\* | 3 |
| All occupancies | Open/outdoor parking | 1.6 |
* LPD for car parks shall calculated from the total lighting power divided by the total car park area
**Table 3.4.6: Applicability of Occupancy Sensors**
| **Occupancy** | **Description** | **Applicability** |
| ------------- | --------------- | ------------------------------- |
| E1 and E2 | Offices | Meeting rooms and corridors |
| A5 | Hotels | Meeting rooms and corridors |
| A3 | Apartments | Covered car parks and corridors |
| B | Educational | Covered car parks and corridors |
#### 4.5.3.2
For car parks a minimum 2/3rd of the lighting shall be controlled by occupancy sensors.
#### 4.5.3.3
Emergency lighting shall not be connected to occupancy sensors.
### **4.5.4 Ceiling/ Wall Mounted Fans**
#### 4.5.4.1
For naturally ventilated buildings of occupancy A, ceiling/wall mounted fans shall be provided in each regularly occupied space.
#### 4.5.4.2
For buildings of occupancy B, C, D, E and I, ceiling/wall mounted fans shall be provided in each room larger than 25 m2 , with a minimum of one fan every 25 m2 .
Exceptions:
* (a) Corridors of buildings of all occupancies
* (b) ICU, CCU, operating theatres of Hospitals and Clinics
### **4.5.5 Lift and Escalator Efficiencies**
#### 4.5.5.1
Escalators, in buildings of all occupancies, shall be fitted with controls to reduce speed or to stop when no traffic is detected.
#### 4.5.5.2
Such escalators shall be designed with one of the energy saving features as described in i or ii below:
* (i) Reduced speed control: The escalator shall change to a slower speed when no activity has been detected for a period of a maximum of three (3) minutes. Detection shall be by photocell activation at the top and bottom landing areas.
* (ii) Use on demand: The escalator shall shut down when no activity has been detected for a period of a maximum of fifteen (15) minutes, designed with energy efficient soft start technology. The escalator shall start automatically when required; activation shall be by photocells installed in the top and bottom landing areas.
#### 4.5.5.3
Elevators (lift) in buildings of occupancy A5, D1, E1, E2, F1, F2, I1 and I3 occupancies shall be provided with controls to reduce the energy demand, using the following features in traction drive elevators:
* (a) AC Variable-Voltage and Variable-Frequency (VVVF) drives on nonhydraulic elevators.
* (b) An average lamp efficacy, across all fittings in the lift car, of >55 lamp lumens/circuit watt, with provision for switching off, when lift is inactive for a period of a maximum of five (5) minutes.
* (c) The provision to operate in stand-by condition during off-peak periods, when the lift has been inactive for a period of a maximum of five (5) minutes.
### **4.5.6 Renewable Energy Options**
#### 4.5.6.1
Buildings of occupancy A shall use Solar or other renewable sources of energy to power 3% of the total electric load of the building, applicable to the uses in Sec 4.5.6.3.
#### 4.5.6.2
Buildings of all occupancies other than A, shall use Solar or other renewable sources of energy to power 5% of the lighting and fan loads of the entire building, mandatory to uses in Sec 4.5.6.3.
#### 4.5.6.3
For all occupancies, the solar or other renewable energy connection shall power spaces in the following order of priority: lighting in underground/basement spaces, dark corridors, supplementary lighting, fans, emergency lighting like fire stairs, emergency signage egress path lighting, etc.
### **4.5.7 Heating Ventilation and Air-conditioning (HVAC) System**
For conditioned buildings, any Heating Ventilation and Air conditioning (HVAC) system planned for installation will meet energy efficiency standards specified in Part 8 of this Code.
## **4.6 Internal Water Management**
### **4.6.1 Reuse of Grey Water**
Buildings of occupancy A5, E1 and E2 and I shall reuse grey water for water efficiency and management.
Grey water from wash basin shall be reused in toilet flushing and/or irrigation after filtration to ensure a BOD (Biochemical Oxygen Demand) level \<50. Such water shall not be considered potable.
### **4.6.2 Efficient Fittings in Toilets**
Water efficient fittings, including faucets, showerheads and flushes, that use less water for the same function as effectively as standard models, shall be used in buildings of all occupancies. The low flow fixtures shown in Table 3.4.7 shall be used.
**Table 3.4.7: Fixture Ratings**
| **Type of Fixtures** | **Quantity (max)** | **Unit** |
| ---------------------- | ------------------ | -------------------------------- |
| Water closets | Dual Flush (6/4) | liters/flushing cycle (full/low) |
| Shower | 9.5 | liters/min at 551 kPa |
| Urinals | 3 | liters/flushing cycle |
| Hand wash taps | 6 | liters/min at 417.7 kPa |
| Kitchen/pantry faucets | 6 | liters/min at 417.7 kPa |
### **4.6.3 Service Hot Water and Pumping**
In order to reduce the energy used for water heating, buildings of occupancy A5 and D1 shall use solar hot water system to supply a minimum of thirty (30) percent of the total building hot water requirements. The solar hot water system can be flat plate solar collectors or vacuum tube solar system, this system must be designed and installed with the backup system or as a per heating for the main hot water system.
# Part III: General Building Requirements
Source: https://docs.sayed.app/bnbc/part-3-general-building-requirements/index
Occupancy classification, fire-resistance classification, and energy efficiency requirements.
Part III covers general building requirements, how buildings are classified by occupancy and by fire-resistance of construction type, and energy efficiency and sustainability requirements.
General requirements that apply across occupancy types.
Occupancy groups and how a building's occupancy classification is determined.
Construction types and their required fire-resistance ratings.
Energy efficiency and sustainability requirements for buildings.
# Chapter 1: General Provisions
Source: https://docs.sayed.app/bnbc/part-4-fire-protection/chapter-1-general-provisions
## **1.1 Scope**
This Part of the Code prescribes regulations for safeguarding life and property in the use or occupancy of buildings or premises from the hazards of smoke and fire, and explosions. The provisions of this Part include general requirements of fire protection, precautionary requirements, means of egress, equipment and in-built facilities standard installations required for firefighting, and firefighting arrangements required for all occupancy groups.
## **1.2 Terminology**
This Section provides an alphabetical list of the terms used in and applicable to this Part of the Code. In case of any conflict or contradiction between a definition given in this Section and that in Part 1, the meaning specified in this Part shall govern for interpretation of the provisions of this Part.
ALARM It consists of a circuit, controls, relays, switches and associated CONTROL UNIT system which receive signals from alarm initiating devices and transmit to alarm signaling devices. ALARM An equipment operated manually or automatically which, when INITIATING activated, initiates an alarm through an alarm signaling device. DEVICE ALARM SIGNAL Signals of audible or visual in nature, indicating the existence of a fire and/or smoke condition. Audible devices may be bells, horns, chimes, speakers or similar devices. Visual Alarms is a strobe light emitting bright white light with approved insanity. ALARM SIGNAL The equipment that produces the alarm signal. DEVICE ALARM SYSTEM It is a combination of compatible devices, which when activated with necessary electrical energy can produce an alarm in the event of fire. ALARM ZONE It describes a defined area of the building or buildings for alarm initiating locations.
| Term | Definition |
| --------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| ANNUNCIATOR | Equipment capable of indicating the zone or area of a building
from which an alarm has been initiated or the location of such
devices and the operational condition of alarm circuit of the
system. |
| AUTOMATIC
FIRE DETECTING
AND ALARM
SYSTEM | These include all types of fire detecting and alarm signaling
devices which activate themselves during a fire without manual
intervention. The equipment/devices include temperature
sensitive fuses, thermostat, fluid filled tubes and electronic
devices which can detect a fire and transmit automatic alarm
signals. |
| AUTOMATIC
SPRINKLER
SYSTEM | The system consists of an array of pipe-works fitted with fusible
solder or glass bulb. This system shall activate at a
predetermined temperature and the required water shall be fed to
the system from any source. In the event of fire or smoke the
system shall activate automatically by sensing the temperature
of fire and discharge water to extinguish. These devices also
actuate an audible alarm automatically. |
| AUTOMATIC
HIGH VELOCITY
WATER SPRAY
SYSTEM | This system applies water in the form of a conical spray
consisting of droplets of water discharged at high velocity
through specially designed projectors to extinguish fire by
emulsification, cooling and smothering. |
| BUILDING | Any structure used or intended for supporting or sheltering any
use or occupancy. |
| BUILDING,
EXISTING | A building erected or officially authorized prior to the effective
date of the adoption of this edition of the Code by the agency of
jurisdiction. |
| CARBON DIOXIDE EXTINGUISHING SYSTEM | This installation consists of a group of one or more cylinders of carbon dioxide, interconnected by a manifold and feeding into a system of high pressure distribution pipe work fitted with special discharge nozzles. |
| COMBUSTIBLE
MATERIAL | Any material which burns and enhances the magnitude of fire. |
| DRY-CHEMICAL EXTINGUISHING SYSTEM | This system consists of specially designed pipe works and discharge nozzles linked to the dry powder containers and gaseous cylinders which are automatically/manually operated in case of fire. |
| DRY RISER | A riser or standpipe system is normally kept empty of water, but
is capable to discharge water within 45 seconds and its
installation is equivalent to wet-riser system. |
| ELEVATOR
EVACUATION
SYSTEM | A system, including a vertical series of elevator lobbies and
associated elevator lobby doors, an elevator shaft(s), and a
machine room(s), that provides protection from fire effects for
elevator passengers, people waiting to use elevators, and
elevator equipment so that elevators can be used safely for
egress. |
| ELEVATOR
LOBBY | A space from which people directly enter an elevator car(s) and
to which people directly leave an elevator car(s). |
| EXTERIOR STAIRWAY | A stairway in which at least one side have openings more than 50% in an Exterior wall in such a way that there shall be no accumulation of smoke during fire. |
| FIRE BARRIER | A fire-resistance-rated wall inside a building, designed to
restrict the spread of smoke and fire. Opening in that wall, shall
be protected by fire protected doors or windows. |
| FIRE
COMPARTMENT | A space within a building that is enclosed by fire barriers on all
sides, including the top and the bottom to limit the transfer of
fire. |
| FIRE DAMPER | A device installed in air ducts or air transfer openings or any
openings designed to close automatically upon detection of fire
or smoke. |
| FIRE DOOR | See Fire door assembly. |
| FIRE DOOR
ASSEMBLY | Any combination of door leaf, frame, hardware and all other
accessories that together provide a specific degree of fire and
smoke protection to the opening where it is placed. |
| FIRE RESISTANCE RATING | It expressed as a period of time and denotes the property of a building construction material or elements and/or construction as a whole during which the materials or elements or constructions are (a) resistant to collapse due to fire, (b) resistant to flame penetration and (c) resistant to excessive temperature rise to the unexposed surface. |
| FIRE SEPARATION | Refers to a fire-resistance-wall or slab between two buildings or
two spaces to protect spread of smokes or fire vertically and
horizontally. |
| FIRE TOWER | Refers to a stairway open or enclosed, detached and isolated
from any building by a distance and can be approached from
various floors of a building or buildings by connecting passage
only. |
| FLOOR AREA,
GROSS | The floor area within the inside perimeter of the outside or
exterior walls of the building under consideration with no
deduction for hallways, stairs, closets, thickness of interior
walls, columns, or other features. Gross floor area of a building
means summation of gross floor areas of all the floors of a
building. |
| FLOOR AREA,
NET | The floor area within the inside perimeter of the outside or
exterior walls of the building under consideration with
deduction for hallways, stairs, closets, thickness of interior
walls, columns, or other features or spaces not used for human
occupancy. |
| FOAM
EXTINGUISHING
SYSTEM | This system discharge foam to extinguish special fires. |
| HORIZONTAL
EXIT | Crossing a fire barrier of a building or connecting building in
the same level shall be treated as horizontal exit. |
| INTERIOR
STAIRWAY | A designated area on ground or on water or on a portion of a
building for helicopter landing or takeoff without servicing,
repairing and refueling facilities. |
| INTERIOR
STAIRWAY | A stairway within a building envelope. |
| PARTY WALL | A fire resistance rated wall where openings are protected, which
is constructed from the ground level and continued up to at least
1m above the roof of a building to restrict the spread of a fire. |
| PUBLIC WAY | A Street, alley, or other similar parcel of land essentially open to
the outside air deeded, dedicated, or otherwise permanently
appropriated for building users or for public use or a single
loaded corridor that is one lateral side opened to outer air,
designed in such a way that there shall be no accumulation of
smoke in case of fire. This corridor may be placed at any level
of a building having a clear width and height of not less than 3
meter having guards and connected to the exit termination or
refuge areas by exterior or enclosed stairs shall be treated as
public way. |
| ROOF REFUGE
AREA | When occupants are relocated at the flat roof of a building
which are not connected with any means of exit shall be treated
as isolated refuge area and must have provisions for placing of
leaders of fire department excess vehicles. |
| SMOKE
DETECTOR | A devise capable of sensing visible or invisible particles
produced during combustion. |
| TRAVEL
DISTANCE | Straight line distance between the remotest point of a space of a
floor and the exit access door placed thereof. |
| TRAVEL PATH | Length of a passage from the remotest point of a space up to the
exit access door placed thereof. |
| VENTILATION | Natural or mechanical intake of fresh air from outside and
removal of inside air of an enclosed space. |
| VESTIBULE | A compartment provided with two or more doors with smoke
lock system where the intended purpose is to prevent continuous
and unobstructed passage by allowing the release of only one
door at a time. |
| VENT, FIRE | A system which activates itself automatically or manually
during a fire or can be activated manually to release the heat and
smoke generated by the fire and smoke. |
| RAMP | A walking surface that has a slope steeper than 1 in 20 and
accessible ramps are not steeper than 1 in 12. |
| WET-CHEMICAL EXTINGUISHING SYSTEM | A system where a solution of water and potassium carbonate and/or potassium acetate based chemical forms the extinguishing agent. |
| WET RISER STAND PIPE SYSTEM | A vertical pipe or consists of an array of pipes installed vertically in a building having landing valves with appropriate outlets at various levels of a building containing charged water at a specified pressure for fire extinguishing purposes. |
## **1.3 General Requirements**
The provisions of this Section shall specify the general requirements in respect of height and area limitations, open space requirements and access facilities for the fire service, which are to be provided for a building to protect it from potential fire hazards.
### **1.3.1 Height and Area Limitations**
The height and area limitations of all buildings and structures shall be governed by the occupancy group classification, floor area ratio and type of construction, which are specified in Part 3 of this Code.
### **1.3.2 Open Space or Fire Separation Requirement**
For the purpose of applying the provisions of open space or fire separation requirements of a building at its side, rear and frontages in Part 3 of this Code shall be followed.
### **1.3.3 Access Facilities for Fire Service**
The access facilities for fire service vehicles and engines shall meet provisions provided in Part 3 of this Code.
## **1.4 Fire Drill**
Fire drills based on fire order shall be arranged to train the occupants of a building in first-aid firefighting, relocation and orderly evacuation. The occupants shall be made thoroughly conversant with fire order, firefighting, and relocation and evacuation procedures in the event of an emergency. The guidelines of fire drill, relocation and evacuation procedure are given in Appendix A.
## **1.5 Fire Tests and Fire Resistance Rating**
The fire resistance rating of individual building construction components shall be determined by standard materials testing procedure as detailed below.
* (a) The fire resistance ratings of building assemblies and structural elements shall be determined in accordance with ASCE 29 or ASTM E 119.
* (b) The construction materials which are intended to be classified as noncombustible shall be tested in accordance with ASTM E 136.
* (c) Flame resistance rating of all materials used for interior finish and trim shall be tested in accordance with ASTM E 84.
* (d) The fire door assemblies shall conform to the test requirements of ASTM E 152.
* (e) The fire windows and fire shutters shall meet the test requirements of ASTM E 163.
* (f) The fire resistances rating of structural elements are provided in Table 4.1.1. For details refer to ASCE 29.
**Table 4.1.1: Fire Resistance of Structures**
*Minimum Equivalent Thickness of Concrete Walls, Floors, and Roofs for Fire Resistance Rating*
| Concrete Aggregate Type | 1 hr (in) | 1 hr (mm) | 1.5 hr (in) | 1.5 hr (mm) | 2 hr (in) | 2 hr (mm) | 3 hr (in) | 3 hr (mm) | 4 hr (in) | 4 hr (mm) |
| ----------------------- | --------- | --------- | ----------- | ----------- | --------- | --------- | --------- | --------- | --------- | --------- |
| Siliceous | 3.5 | 89 | 4.3 | 109 | 5.0 | 127 | 6.2 | 157 | 7.0 | 178 |
| Carbonate | 3.2 | 81 | 4.0 | 102 | 4.6 | 117 | 5.7 | 145 | 6.6 | 168 |
| Sand-light weight | 2.7 | 69 | 3.3 | 84 | 3.8 | 97 | 4.6 | 117 | 5.4 | 137 |
| Lightweight | 2.5 | 64 | 3.1 | 79 | 3.6 | 91 | 4.4 | 112 | 5.1 | 130 |
*Minimum Column Dimension for Fire Resistance Rating*
| Concrete Aggregate Type | 1 hr (in) | 1 hr (mm) | 1.5 hr (in) | 1.5 hr (mm) | 2 hr (in) | 2 hr (mm) | 3 hr (in) | 3 hr (mm) | 4 hr (in) | 4 hr (mm) |
| ----------------------- | --------- | --------- | ----------- | ----------- | --------- | --------- | --------- | --------- | --------- | --------- |
| Siliceous | 8 | 203 | 9 | 229 | 10 | 254 | 12 | 305 | 14 | 356 |
| Carbonate | 8 | 203 | 9 | 229 | 10 | 254 | 11 | 279 | 12 | 305 |
| Sand-light weight | 8 | 203 | 8.5 | 216 | 9 | 229 | 10.5 | 267 | 12 | 305 |
*Minimum Required Equivalent Thickness of Masonry for Fire Resistance Rating*
| Clay Masonry Unit | 0.5 hr (in) | 0.5 hr (mm) | 0.75 hr (in) | 0.75 hr (mm) | 1 hr (in) | 1 hr (mm) | 1.5 hr (in) | 1.5 hr (mm) | 2 hr (in) | 2 hr (mm) | 3 hr (in) | 3 hr (mm) | 4 hr (in) | 4 hr (mm) |
| ------------------------------------------------------------------------------------------------ | ----------- | ----------- | ------------ | ------------ | --------- | --------- | ----------- | ----------- | --------- | --------- | --------- | --------- | --------- | --------- |
| Brick of clay or shale, unfilled | 1.7 | 43 | 2.0 | 51 | 2.3 | 58 | 2.85 | 72 | 3.4 | 86 | 4.3 | 109 | 5.0 | 127 |
| Brick of clay or shale, grouted or filled with perlite, vermiculite, or expanded shale aggregate | 2.3 | 58 | 2.65 | 67 | 3.0 | 76 | 3.7 | 94 | 4.4 | 112 | 5.5 | 140 | 6.6 | 168 |
## **1.6 Related Appendix**
Appendix A Fire Drill and Evacuation Procedure
# Chapter 2: Precautionary Requirements
Source: https://docs.sayed.app/bnbc/part-4-fire-protection/chapter-2-precautionary-requirements
## **2.1 Occupancy Classification**
All buildings shall be classified according to their use or by considering the character of their occupancy. For the purpose of this Code, the occupancy classification groups shall be as follows:
* Occupancy A: Residential
* Occupancy B: Educational
* Occupancy C: Institution for care
* Occupancy D: Health Care
* Occupancy E: Business
* Occupancy F: Mercantile
* Occupancy G: Industrial
* Occupancy H: Storage
* Occupancy I: Assembly
* Occupancy J: Hazardous
* Occupancy K: Garages
* Occupancy L: Utilities
* Occupancy M: Miscellaneous
The details of occupancy classification of buildings are provided in Part 3 of this Code.
## **2.2 Classification of Construction Types**
For the purpose of this Code, every room or control area or space of a building or a building itself hereafter altered or erected shall be classified in one specific type of construction as grouped as follows:
GROUP I- Non-combustible, subdivided as follows:
* Type- I A 4 hour protected
* Type- I B 3 hour protected
* Type- I C 2 hour protected
* Type- I D 1 hour protected
* Type- I E Unprotected
GROUP II- Combustible, subdivided as follows:
* Type- II A Heavy timber
* Type- II B Protected wood joist
* Type- II C Unprotected wood joist
* Type- II D Protected wood frame
* Type- II E Unprotected wood frame
The types of construction are based on fire resistance of construction elements, which are detailed in Part 3 of this Code.
## **2.3 Fire Zones**
The development areas of a city, township or municipality or union shall be divided into Fire zones as distinct areas based on the inherent fire hazards of the buildings to be constructed and the degree of safety desired for the occupancy group accommodated therein.
## **2.4 Mixed or Separated or Detached Occupancy**
Where two or more occupancy types are amalgamated in a floor or in a building shall be designated as mixed occupancy shall be allowed as per provisions of A-Z list of Part 3 and this Code.
Where two or more occupancy types are in groups in a floor or in a building and separated as specified in the Table 3.2.1 of Part 3 and as per provisions of this Code shall be designated as separated Occupancy.
Hazardous occupancy J shall not be allowed as mixed or separated occupancy with any other occupancy classification as per provisions of this Code.
Building structures are isolated by fire separation distances as per provision of this Code shall be designated as detached occupancies.
## **2.5 Openings In Separation Wall**
Opening means a hole or an aperture in the building envelope or in any wall within the building through which air can pass. Protective type opening means a hole or an aperture shall have open able closures with fire resistive assemblies to restrict air movement.
Separation wall not constructed monolithically or homogeneously and having joints shall be complied with requirements of smoke lock and fire resistance rating as per provisions of this Code.
Vertical solid elements which create a barrier within a space or create a building envelope shall be designated as wall or partitions as per provisions of this Code.
* (a) The openings in occupancy separation wall shall conform to the provisions set forth in the Part 3 of this Code.
* (b) Openings in fire separating walls and floors shall not exceed the approved limit and the opening shall be of protective type and conform to the approved provisions of this Code.
* (c) Fire separation walls shall not have opening exceeding 11.2 m2 in area and the aggregate width of all openings at any floor level shall not exceed 25 percent of the length of the wall. When an entire storey floor area has fire separation walls on two opposite sides have openings shall be covered by automatic fire suppression system, the maximum allowable opening may be doubled with a minimum distance of 0.9 m between adjacent openings.
* (d) Each protected openings in a fire separation wall shall be limited to 5.6 m2 in area with a maximum height of 2.75 m and width of 2.20 m. Wall or floor openings shall be protected with approved fire resisting means conforming to approve standards as per provision of this Code. When openings in floors have protected enclosures or have enclosure walls which form a shaft and have openings on enclosure wall shall be protected by fire assemblies.
* (e) Openings of service lines like cables, electrical wirings, telephone cables, plumbing fixture etc. shall be protected by enclosures having an approved fire resistance rating. Medium or low voltage electrical wire running through shaft or ducts shall be either armoured or cased within metal conduits as per provisions of Part 8 of this Code.
* (f) All openings in the fire separation walls shall be protected with fire resistance assemblies or automatic fire suppression system as per provisions of this Code.
## **2.6 Smoke and Heat Vents**
Interior or indoor air qualities are maintained as good as natural outdoor air qualities as per provisions of this Code through openings in the building envelope shall be designated as Natural Ventilation.
Interior or indoor air qualities are maintained by the means of mechanical devices shall be designated as Mechanical Ventilation. Restricted ventilation means excessive smoke accumulation within a building during fire.
* (a) Smoke and heat vents shall be installed in areas of restricted ventilation such as windowless buildings, underground structures, and factories floor spaces of restricted ventilation.
* (b) Where exit access travel distance is more than 23 m, smoke and heat vents shall be constructed in accordance with the provisions of this Code.
* (c) The vent area and spacing of the vents shall comply with Table 4.2.1.
* (d) Closures of natural draft, smoke and heat vents shall be installed in such a way that fire service personnel can open it easily during a fire.
* (e) Smoke and heat vents on roof or ceiling or wall shall normally be kept open. In case of closed vents, automatic activation of the openings by heat responsive device rated at 38o C to 104o C above ambient shall be a requirement. The releasing mechanism shall be capable of opening the vent fully when the vent is exposed to a time-temperature gradient that reaches an air temperature of 260o C within 5 minutes. The vents shall also be capable of being opened by manual operation.
* (f) Fire Vents requirements for Industrial and Storage Buildings are given in Appendix B of Part 4.
**Table 4.2.1: Smoke and Heat Vent Size and Spacing**
| **Use group** | **Hazard**
**Condition** | **Vent Area to**
**Floor**
**Area Ratio** | **Max Spacing**
**of**
**Vent Centres** |
| -------------------- | ----------------------------- | --------------------------------------------------- | ------------------------------------------------- |
| Occupancy H1 | Low Hazard | 1:150 | 45 m |
| Occupancy H2 | Moderate Hazard | 1:100 | 36 m |
| Occupancy J1 | High Hazard | 1:30 to 1:50 | 22.5 m to 30 m |
| Occupancy J2, J3, J4 | High Hazard | 1:30 to 1:50 | 22.5 m to 30 m |
| Occupancy K1, K3 | Low Hazard | 1:150 | 45 m |
## **2.7 Electrical, Gas and Hvac Services**
The requirements of the electrical, HVAC and gas services shall meet the provisions of Part 8 of this Code.
* (a) Air-conditioning and ventilation systems shall be installed and maintained as per provisions of this Code so that the fire, fumes or smoke do not spread from one area of fire to other area of a building through the ducts or vents.
* (b) Properly designed fire dampers shall be installed within the air-conditioning and ventilation ducts, which shall automatically close the flow of air in case of fire.
* (c) For large assembly areas, department stores and hotels with more than 100 rooms in a single block, effective means for preventing circulation of smoke through the air-conditioning ducts shall be installed. Such means shall consist of approved smoke sensing control devices, where fuses of dampers may not function during early state of a fire due to insufficient heat as per provisions of this Code.
## **2.8 Surface Finishes**
Materials used to trim or cover the interior and the exterior surfaces of a building have the potential of generating smoke and toxic fumes during a fire and have the potentiality of changing the nature of fire due to its ignitability as fuel. Use of such finish materials shall be classified as per provisions of this Code.
* (a) The fire susceptibility of various types of surface finishes shall be determined in terms of the rate of spread of fire (ASTM E 84). Based on the rate of spread of fire, the surface finish materials shall be classified into three (3) classes:
* Class I Surfaces of low flame spread: Flame does not effectively spread more than 300 mm in the first 1.5 minutes with an ultimate value of 600 mm.
* Class II Surfaces of medium flame spread: Flame does not spread effectively more than 300 mm and 850 mm in the first 1.5 minutes and 10 minutes respectively.
* Class III Surfaces of rapid flame spread: Flame spreads effectively more than 300 mm and 850 mm in the first 1.5 minutes and 10 minutes respectively.
* (b) Interior finish of walls and ceilings shall have a flame spread rating not greater than those in Table 4.2.2 for various occupancy classes.
**Table 4.2.2: Acceptable Flame Spread Rating Classes of Interior Finish**
| **Occupancy** | **Class/Use Group** | **Vertical Exits**
**and Passage**
**Ways** | **Corridors**
**Providing Exit**
**Access** | **Rooms or**
**Enclosed Areas** |
| ------------------------------------------------------------------------------------------------------------------ | --------------------------------------- | ----------------------------------------------------- | ----------------------------------------------------- | ------------------------------------ |
| A1 | Detached single family
dwelling | III | III | III |
| A2 | Two family dwelling | I | I | II |
| A3 | Flats or Apartment | I | I | I |
| A5 | Hotels and Lodging
Housing | I | I | I |
| B | Educational | I | I | I |
| C1, C2 | Institutional, Residential & custodial | I | I | III |
| C3 | Institutional-Incapacitated | I | I | I |
| C4 | Institutional- Restrained | I | I | I |
| D | Health Care | I | I | I |
| E | Business | I | II | II |
| F | Mercantile | I | II | II |
| G | Industrial | I | II | II |
| H | Storage | III | II | III |
| I1 | Large assembly with
fixed seats | I | I | I |
| I2 | Small assembly with
fixed seats | I | I | I |
| I3 | Large assembly without
fixed seats | I | I | I |
| I4 | Small assembly without
fixed seats | I | I | I |
| J | Hazardous | I | II | III |
| Note: Class III may be adopted Instead of Class II where the area is covered by automatic fire suppression system. | | | | |
## **2.9 Glazing Assemblies**
* (a) Buildings of construction shall use any one of the following types of glazing using wire glass by electro-copper or equivalent. Building of construction types as designated as unprotected or combustible may use hardwood sashes or frames or both.
* (b) Glazing system used partially or as a whole to fulfill fire separations or fire barriers requirements as per provisions of this Code shall be the equivalent of required fire resistance rating. Glazed doors, windows or partitions or wall with appropriate smoke lock along with other safety due to fragility, translucency or transparency shall be correctly installed. Such fire-resistant glazing assembly must function as an integral system together with the frame, beads, bead fixings, glazing materials and frame fixings all working together with compatibilities with the standards installation as per provisions of this Code.
* (c) Wired glass panels shall comply with the following requirements:
* (i) Thickness of the glass shall not be less than 6 mm.
* (ii) Embedded wire netting mesh in the glass shall not be more than 25 mm mesh.
* (iii) The sashes or frames or both shall be entirely made up of iron or any other approved metal. The frame shall be securely fixed into the wall (except panels of internal doors).
* (iv) Setting of the panels of glass shall be achieved by rebates or grooves of not less than 6 mm diameter/width or depth keeping due allowance for expansion. The glass shall be secured to the frame by hard metal fastenings. Approved sealants may be used for weather proofing.
* (v) Where wired glass panels are labelled as protective openings, they shall conform to the size limitations shown in the Table 4.2.3.
**Table 4.2.3: Limitations of Wired Glass Panel sizes in Protective openings**
| **Required Fire Resistance Rating** | **Max Height (m)** | **Max Width (m)** | **Max Area (m****2****)** |
| ------------------------------------------------------------------------------------------------- | ------------------ | ----------------- | ------------------------------------ |
| 3 hours | NP | NP | NP |
| 1 1
2
hour door in exterior walls | NP | NP | NP |
| 1 1
2
hour fire rating | 0.85 | 0.25 | 0.065 |
| 3
4
hour fire rating | 1.4 | 1.4 | 0.85 |
| Fire windows | 1.4 | 1.4 | 0.85 |
| Note: Size limitations are not applicable for Fire Rated Glazing Assemblies. NP = Not Permitted. | | | |
* (d) Electro-copper glazing shall comply with the following requirements:
* (i) Thickness of the glass shall not be less than 6 mm.
* (ii) Not more than 0.4 m2 of square glass shall be formed by electro-copper glazing in sectional lights.
* (iii) The sashes or frames or both shall be entirely made up of iron or any other approved metal. The frame shall be securely bolted into the wall (except panels and internal doors).
* (iv) Setting of the panels of glass shall be achieved by rebates or grooves of not less than 6 mm width or depth keeping due allowance for expansion. The glass shall be secured to the frame by hard metal fastenings. Approved sealants may be used for weather proofing.
* (e) Wall opening more than 5 m2 shall not be deemed to be effectively protected by wired glass or electro-copper glazing.
* (f) Wired glass or electro-copper glazing not exceeding 0.85 m2 in area shall be allowed provided it is cased in hard metal and secured to the frames by hard metal hinges not exceeding 60 mm apart and by fastening at top, centre and bottom.
## **2.10 Skylights**
* (a) Wired glasses used in skylights shall comply with the following requirements:
* (i) Thickness of the glass shall not be less than 6 mm;
* (ii) Wire netting mesh embedded in the glass shall not be more than 25 mm square;
* (iii) The glazing shall be caged in frame of continuous metal divided by bars 750 mm apart centre to centre. The frame and bars shall be iron or other approved metal (or of hard wood covered with sheet metal). The glass shall be secured to the frame by hard metal fastenings. Approved sealants may be used for weather proofing.
* (b) Single opening for Skylight more than 5 m2 shall not be deemed to be effectively protected by wired glass.
## **2.11 Fire Lifts**
* (a) Fire lifts shall be installed as per provisions of this Code. Fire lifts, where installed shall be fully automated from the ground level with all though fire rated and protected wiring and switches and shall have a minimum capacity of 8 persons.
* (b) Fire lifts shall be operated and maintained by the inmates of building except during fire. During fire, Firemen shall takeover to operate such lifts.
* (c) Fire lifts shall be equipped with approved two way voice communication with the fire command station or control room or security room on the exit termination level of a building.
* (d) Number and location of fire lifts in a building shall be decided on the basis of total occupant load, floor area and compartment.
* (e) A Lift shaft or bank shall be dedicated to Fire lift.
* (f) The speed of the lift shall be such that it can reach the top floor from ground level (non-stop) within 1 minute.
* (g) Smoke detectors shall be installed at a distance of 3m from every entry doors of Fire Lifts and links with corresponding lift control panel to prevent lift doors to open in case of fire at any level.
* (h) All lifts in tall structure shall be operable during fire. There shall be provisions for firemen to take over the control of lift operation as per provision of this Code.
* (i) All stretcher and hospital lifts shall be operable during fire. There shall be provisions for firemen to take over the control of lift operation as per provision of this Code.
* (j) Lifts installed for accessibility shall be operable during fire. There shall be provisions for firemen to take over the control of lift operation as per provision of this Code.
* (k) Lift lobby shall be connected with at least one fire stair by a means of exit component.
## **2.12 Utilities (Occupancy L) and Exempted Quantities of Hazardous Material**
Occupancy type L is a separated occupancy from the main occupancy classifications to provide ancillary electro-mechanical service facilities require a special attention which shall be taken as per provision of this Code. Utilities (Occupancy L) and exempted quantities of hazardous materials for different occupancies are given below:
### **2.12.1 Occupancy A: Residential**
* (i) Flammable liquids used for domestic purposes shall be kept adequately sealed in approved containers within the limit of exempted quantity at all times.
* (ii) Stoves and heaters using open flame shall be so located at defined space with proper precaution.
* (iii) Exhaust fans used in kitchens shall be placed on a peripheral wall of the building or to a duct connected directly to outside and shall be made of noncombustible material. The duct shall not pass through combustible materials.
* (iv) Doors leading into a room containing flammable liquids shall be provided with self-closing devices. Appropriate signs identifying the storage materials and requesting the users to keep the door closed shall be marked on both sides of the door.
* (v) All outdoor roof top antennas shall be protected by proper lightning arrester.
* (vi) Rooms containing boiler shall be separated from the main building by appropriate separation wall with all its openings protected as per provisions detailed in Sec 2.3 of Part 3 and Sec 2.5 of this Chapter.
* (vii) Areas or rooms within the building identified as Control Area shall be protected or segregated by appropriate separation wall or by other approved means as per the provisions of this Code.
### **2.12.2 Occupancy B: Educational**
* (i) Control areas containing volatile flammable liquids shall be separated from the adjoining areas in as per provisions of this Code.
* (ii) Gas pipeline entering any building shall be equipped with shutoff valves outside the building with conspicuous marking clearly delineating the location as per provisions of Part 8 of this Code.
* (iii) The openings of boiler rooms shall be adequately protected by fixed, automatic or self-closing fire assemblies.
### **2.12.3 Occupancy C: Institutional**
Permit shall not be granted for storage or handling of any hazardous material even in control areas, except for normal use in amounts not exceeding the exempted amounts specified in Chapter 2 of Part 3, in a building or part thereof classified as Occupancy C.
### **2.12.4 Occupancy D: Health Care**
Storage of volatile flammable liquids such as chloroform, ethyl alcohol, mentholated spirit etc. shall be stored in Control Areas and no unauthorized person shall be allowed to handle such liquids.
### **2.12.5 Occupancy E: Business**
* (i) Exit aisles or approaches in self-service in a space shall not be obstructed by placing checkout stand with associated railings or barriers on its passage.
* (ii) All operations in open air markets, refuelling stations, road side stands for sale of farm products etc. shall be so conducted that unobstructed access to exits are always maintained.
### **2.12.6 Occupancy F: Mercantile**
Provisions are same as those of Sec 2.12.5 (Occupancy E).
### **2.12.7 Occupancy G: Industrial**
* (i) Apparatus are not capable to igniting flammable vapour shall be permitted within a control area of a building using or processing or storing volatile flammable liquid. Control Areas of a building using or processing or storing such flammable liquid shall be covered by exhaust ventilation system.
* (ii) Boiler rooms and areas containing heating plants shall be separated from the rest of the occupancy as per provisions of this Code.
* (iii) Adequate protective measures shall be taken against hazards associated with distribution and use of electricity and gas in accordance with the provisions of Chapters 2 and 8 of Part 8.
* (iv) The machine layout shall be congenial to safe fire practice.
### **2.12.8 Occupancy H: Storage**
* (i) Apparatus are not capable to igniting flammable vapour shall be permitted within a Control area or part of a building using or storing volatile flammable liquid. Control Areas of a building using or storing such flammable liquid shall be covered by exhaust ventilation system.
* (ii) Boiler rooms and areas containing heating plants shall be effectively segregated from the main occupancy.
* (iii) Adequate protection shall be taken against hazards associated with distribution and use of electricity and gas in accordance with the provisions of Chapters 2 and 8 of Part 8.
### **2.12.9 Occupancy I: Assembly**
* (i) All materials used for decorative purposes in buildings of Occupancy I shall be non-combustible. If fabrics and papers are used for decorative purposes, shall be treated with flame resistant chemicals/materials.
* (ii) Rooms and parts of a building containing high pressure boilers, refrigerating machinery, large transformer or other service equipment having explosion potential shall not be located on or adjacent to the defined exit route. Such rooms shall be effectively cut off from the rest of the building and connected to open air through approved ducts or openings.
* (iii) Rooms or parts of a building used for storage of combustible materials such as paints or other items shall be effectively cut off from main assembly building or protected by approved automatic sprinkler system. Such areas shall be away from staircases.
* (iv) Legitimate stages having such facilities as fly galleries, gridirons and rigging shall be covered by an automatic sprinkler system above and below such stage areas or spaces. Auxiliary spaces such as dressing rooms, store rooms, and workshops and the proscenium opening shall be effectively covered by fire resistant curtains capable of withstanding a lateral pressure of 4 kN/m2 . The curtain shall be equipped with self-closing emergency device and when closed shall be tight enough to prevent spread of smoke.
* (v) Legitimate stage roof above every theatre using movable scenery or motion picture screen constructed of highly combustible materials shall be fitted with ventilators in or above it. The ventilators shall be operable from the stage
floor manually or by fusible links or some approved automatic heat actuated device to give an opening to sky with an area of one-eighth the area of the stage.
* (vi) In theatres not protected by automatic fire sprinklers, the proscenium wall using movable scenery of decorations shall be provided with maximum of two openings to enter the stage and each opening shall not be of more than 2 m2 .
* (vii) Film projection apparatus shall be enclosed within fire resistant enclosures.
* (viii) Auditoriums of theatres and cinemas shall be installed with vents on roof having vent area equal to the floor area including balconies and galleries, boxes and tiers. Larger numbers of smaller vents shall be preferable over smaller number of larger vents.
### **2.12.10 Occupancy J: Hazardous**
* (i) Equipment and machinery in operations, igniting and/or emitting combustible volatile substances shall be installed in a standard environment as recommended in NFPA or equivalent standards.
* (ii) Rooms containing boiler or heating plant shall be effectively separated from the main occupancy.
### **2.12.11 Occupancy K: Garage**
As per safety requirement of NFPA or equivalent standard.
### **2.12.12 Occupancy L: Utility**
As per safety requirement of NFPA or equivalent standard.
### **2.12.13 Occupancy M: Miscellaneous Buildings**
As per safety requirement of NFPA or equivalent standard.
## **2.13 RELATED APPENDIX**
Appendix B Fire Protection Considerations for Venting in Industrial and Storage Building.
# Chapter 3: Means of Egress
Source: https://docs.sayed.app/bnbc/part-4-fire-protection/chapter-3-means-of-egress
## **3.1 scope**
The provisions of this Section shall control the design, construction and arrangement of building components to provide a reasonably safe means of egress. Any repair or alteration works within a building shall be prohibited unless the existing means of egress and fire protection system are continuously maintained or a continuous alternative exits and protection measures are taken to provide an equivalent degree of safety for the occupant and the workers for the total duration of such project.
## **3.2 Components of Means of Egress**
### 3.2.1
A means of egress is an evacuation system with the provisions of reentry for rescuers and fire fighters where a continuous and unobstructed way of exit travel shall be provided from any point within a building to a designated area of refuge for allowable delayed evacuation and ended up with the exit termination by reaching a street abutting building or plot or an safe area which is open to air and designated assemblies for evacuees.
The way of exit travel within a building form any point thereof along a means of egress shall consist of three parts: (1) the exit access, (2) the exit, and (3) the exit discharge
* (a) A way or path of evacuation from any point of an area affected due to fire incident leads to a protected entry to another separated area of a building shall be termed as exit access. Straight line distance between the remotest point of an area of incident and the entrance point of a separated area shall be measured and termed as a travel distance.
* (b) The exit is a component or a group of components start with a protected opening to evacuate an area of fire incidence and provides a safe entry to a separated area which is component of means of egress and subsequently leads to the exit discharge.
* (c) The outer edges or peripheral points of a building from where occupants shall evacuate the building envelope termed as Exit discharges which shall lead evacuees to the terminal points at a safe distance from thereof.
An area or any plot abutting street which is open to air and designated for systematic assemblies of evacuees to complete the process of egress system shall be termed as exit termination.
### 3.2.2
The parts of the means of egress consist of any of the following exit components:
* (a) A doorway, separated or refuge area like smoke and fire proof enclosure, compartment, corridor, passage, ramp, balcony, an exterior or open or interior fire stair, or any combination of these, leads orderly to the exit discharge which offer safety from fire or smoke from the area of incidence.
* (b) Horizontal exit shall provide a delayed egress by relocating the occupants from their initial location due to a fire incident to a separated area at same level of a same building or at the same level of adjoining or detached buildings connected through a fire door or a vestibule or a passage or corridors for relocation of evacuees. Receiving areas are capable to accommodate expected evacuees for certain time period, free from heat, smoke and aggressive fire, from the area of incidence and shall lead to exit discharges without returning the evacuees to their initial locations.
### 3.2.3
Generally lifts, escalators and moving walks shall not be regarded as components of means of egress. When they are designed and installed for safe operation during fire shall be included as components of means of egress.
### 3.2.4
Means of Escape: A way out of a building or structure that does not conform to the formation of means of egress but does provide a safe way out.
## **3.3 General Requirements**
### **3.3.1** Design considerations or assumptions:
* (a) Fire initiated from only one source in single space shall aggravate within a building or adjacent structures over a time period.
* (b) More than one space or source of fire at the same time shall not be considered.
* (c) All Construction Materials by qualities and quantities including surface finish, utilities, fabrications of movables and immovable, stored materials shall be approved types as per provisions of this Code.
* (d) Stability of structural elements or building itself shall be as per provisions of this Code.
* (e) Occupants, Rescuers and fire fighters life safety shall be the prime consideration thus egress system including relocation and fight in place or evacuation and reentry provisions shall be as per provisions of this Code.
* (f) Fire suppression and extinguishment arrangement for life safety and minimize property damages shall be performance based as per provisions of this Code.
* (g) Provisions of this Part shall be the minimum standard, in excess of these provisions shall not be prevented to design a egress system or to install advance and higher standard of detection and extinguishment equipment or both which shall be approved by the authorities having jurisdiction.
### 3.3.2
All buildings constructed for human occupancy or control areas or storages shall be provided with adequate exit facilities to permit safe and quick unaided egress of the occupants in the event of fire or other emergency.
### 3.3.3
Exits shall not be used for any other purpose at any time that would obstruct the intended use of those components during emergency.
### 3.3.4
Where corridors or passages are components of exits shall not be designed or used as components to supply or return air.
### 3.3.5
Preferences of levels of walking surfaces in the means of egress shall be more than 1 in 20. Ramps or stairway shall be used in case of changes in elevations of walking surfaces.
* (a) Abrupt changes not exceeding 130 mm but exceeding 60 mm shall be beveled 1 in 2.
* (b) Changes in elevation exceeding 130 mm shall be considered as a change in level.
* (c) A stairway in walking surface of the means of egress shall consist of minimum two steps and all of them shall be identical and shall have tread depth not less than 330 mm and height of risers shall not be exceeded more than 230 mm but shall comply tread and riser combination as per provision of this Code.
* (d) Changes in levels 530 mm or more in walking surfaces of the means of egress shall be achieved either by a ramp or by a stairway.
* (e) Presence and location of such steps or ramps in the walkways shall be readily apparent.
* (f) Other than ramp, a slope of walking surfaces along the direction of travel shall not be steeper than 1 in 20 and slope perpendicular to the travel direction shall not be exceeded 1 in 48.
* (g) Slope of ramps shall be complied with the accessibility where required as per provisions of this Code.
### 3.3.6
From the exit access all exits shall be clearly visible. Corridors and passages leading to the exit discharge shall be marked and signposted to guide the evacuees as per provisions of this Code. A space used in darkness having more than one exits shall be illuminated exits sign as per provision of this Code.
### 3.3.7
The owner or lessee of all new and existing buildings shall be responsible to provide the safety provisions for all occupants and rescuers and firefighters. If in any existing building, the exit facilities are deemed inadequate in view of the requirements of this Code, the authority having jurisdiction may order to comply with the provisions of this Code.
## **3.4 General Provisions of Exits**
### 3.4.1
All exits shall be easily discernible and accessible from the areas served by them.
### 3.4.2
Exit from any room or space shall not open into an adjoining or intervening room or area except where such adjoining room or area is an accessory to the area served, is not a hazardous occupancy. If hazardous or a control area, provide a direct exit to the outside of a building envelope or directly connect with the components of egress system.
### 3.4.3
No portion of Exits shall pass through a room that may be subject to lock with detachable key or be intervened by a door that may have detachable key operated lock and the door is locked when the building is occupied.
### 3.4.4
All entry points to the assembly occupancy shall serve as Exits and shall have the total capacity for at least one-half of the total occupant load. Provisions of exits other than entries shall have capacity to evacuate at least two-thirds of occupant from each level of assembly occupancy.
### 3.4.5
All exits shall be so located and arranged that they shall provide continuous and unobstructed means of egress up to the exit discharge.
## **3.5 Occupant Load**
Total occupant load means summation of all occupants of only one level at the pick hour occupancy where maximum occupants are present.
Occupant load shall be considered as per provisions of this Code to design each and every component of means of egress system shall be termed as design occupant load.
### **3.5.1 Design Occupant Load**
The design occupant load for which the component of means of egress is to be provided shall be the highest number computed as per the provisions of (a), (b) and (c) as stated below:
* (a) The actual number of occupants for whom the area served by the exits is designed;
* (b) Number of occupants shall be computed as prescribed in Table 4.3.1.
* (c) The number of occupants in any area shall be computed as per provisions of (a) or (b) as stated above and in all cases the higher value shall govern the design.
* (d) The computation of design occupant load shall be the summation of occupants of a space and the evacuees of other spaces whose are using the said space as for waiting or passing through in case of emergency to gain an access to a component of means of egress.
**Table 4.3.1: Occupant Load Factor**
| **No.** | **Occupancy** | **Unit of Floor Area in m****2** **per Occupant**\* |
| ------- | ---------------------------------------------------------------------- | -------------------------------------------------------------- |
| A | Residential | 18 gross |
| B | Educational: | |
| | Class room | 2 net |
| | Preschool | 3.5 net |
| C | Institutional | 12 gross |
| D | Health Care: | |
| | In patient areas | 15 gross |
| | Out-patient areas | 10 gross |
| I |
Assembly: | |
| | with fixed seats | Number of seats designed. |
| | with movable seats | 0.93 net |
| | standing space only | 0.37 net |
| | with table and chairs | 1.5 net |
| | Passengers that can be unloaded | |
| | simultaneously to a terminal or a
platform | 0.15 net |
| E | Business: Office Space | 3 gross |
| F |
Mercantile: | |
| | Retail sales Area, Ground floor
or Basement
All other floor | 2.3 net
4.6 net |
| G | Industrial | 10 gross |
| H | Storage | 20 net |
| K | Garages and open parking structures | 23 net |
| L | Utility | Actual occupant load |
| M | Miscellaneous Building | Actual occupant load |
* As per Sec 3.5.1(b) of this Chapter, design occupant load shall be calculated and any fraction shall be rounded to next higher integer value. Width of all components of egress system shall satisfy requirements of specified in the Table 4.3.2
### **3.5.2 Fixed Seats**
The occupant load for an assembly or educational area having fixed seats shall be determined by the seating capacity of the area. For fixed seats without dividing arms, the capacity shall be taken as one person for every 500 mm of seat.
### **3.5.3 Maximum Occupant Load**
The design occupant load, need not to be calculated more than one person per 0.3 m2 of usable floor space.
### **3.5.4 Mezzanine Floors**
The occupants of a mezzanine floor evacuating through other floors the occupant load shall be added to the receiving floors.
### **3.5.5 Roofs**
A Roof, an open air space used as assembly or refuge area, educational or other types of human occupancy shall be provided with exit facilities as per provisions of this Code.
## **3.6 Capacity of Exit Components**
### 3.6.1
The capacity of egress components shall be complied with the occupant load of the area served. The required width of each component shall be computed on the basis of the allotted width per occupant prescribed in Table 4.3.2, subject to the minimum widths
of such components specified in Sections 3.7 to 3.12 and the travel distances of such components as per provision of this Code.
**Table 4.3.2: Required Width per Occupant**
| Occupancy | | Without Sprinkler — Stairways | Without Sprinkler — Ramps & Corridors | Without Sprinkler — Doors | Sprinkled — Stairways | Sprinkled — Ramps & Corridors | Sprinkled — Doors |
| --------------------- | ------------------------------------------------------------------- | ----------------------------- | ------------------------------------- | ------------------------- | --------------------- | ----------------------------- | ----------------- |
| A, B, E, F1, F2, G, H | Residential, Educational, Business, Mercantile, Industrial, Storage | 8 | 5 | 4 | 5 | 4 | 4 |
| C1, C2 | Institutional | 8 | 5 | 4 | 5 | 5 | 4 |
| C3, C4, C5 | Institutional | 10 | 5 | 4 | 8 | 5 | 4 |
| D | Health Care | 25 | 18 | 10 | 15 | 12 | 10 |
| I, F3 | Assembly, Mercantile | 10 | 7 | 5 | 7 | 5 | 5 |
| J | Hazardous | 8 | 5 | 4 | 8 | 5 | 4 |
| K, L, M | | 8 | 5 | 4 | 5 | 4 | 4 |
All values are in mm per person. Width of the components of egress shall be divided by the value specified in this table to determine the maximum allowable occupant load served by them.
## **3.7 Corridors and Passageways**
### 3.7.1
Occupants commencing exit travel along a corridor or a passageway shall be lead to an exit discharge. Length of dead end corridors and passageways and branches thereof shall not be exceeded as per Sec 3.15.4 of this Chapter.
### 3.7.2
The required width of corridors and passageways shall be calculated on the basis of the occupant load in accordance with the provisions of this Code and shall not be less than as per Sec 3.15.4 of this Chapter.
### 3.7.3
The minimum ceiling height of the corridors and passageways used as a means of egress shall not be less than 2.4 m.
### 3.7.4
All exit corridors or passages shall have a fire resistance rating of 1 hour or more as per provisions of this Code.
### 3.7.5
Protective opening leads to an exit shall be fire doors or fire windows or a fire assembly having a fire resistance rating of at least 20 minutes or more as per provisions of this Code.
* (a) Certified Fire resistance rating of Doors shall be in accordance with ASTM E152 without the hose stream test.
* (b) Fire resistance rating of the fire door assembly has to perform as required 20, 30, 60, 90, 180 minutes or more shall be leveled A, B, C, D, E and F respectively.
* (c) Fire door assembly of any approved materials shall qualify through ASTM E152 without the hose stream test.
## **3.8 Assembly Seating and Waiting**
* (a) Assembly buildings primarily meant for theatrical, operatic performances or cinematic projection shall have the seats securely fastened to the floor with exceptions as permitted in this Code. All seats in balconies and galleries shall be securely fastened to the floor except boxes with level floor and less than 14 seats.
* (b) Seats not fixed to the floor shall be permitted in restaurants and such other places provided that 1.25 m2 of floor space is allotted for every seat excluding dancing floor and stage. Adequate aisles shall be maintained at all times to reach exits without obstruction when such occupancies are in use.
### 3.8.1
Assembly buildings which contain seats, tables, equipment or exhibitions or displays shall be provided with aisles, free of obstructions, leading to the exit.
### 3.8.2
Minimum clear widths of steeped aisles and other means of egress serving assembly seating shall be calculated on the basis of number of seats and in accordance with Table 4.3.3. Interpolation shall be permitted between the specific values shown thereof. The minimum clear width of steeped aisles as found by above calculation shall be modified in accordance with the conditions stated below:
* (i) If risers exceed 178 mm in height for steeped aisles the width of the steeped aisles as shown in the table shall be multiplied by factor *a* ,
* (ii) In the Table 4.3.3 values of steeped aisles not having a handrail within a 760 mm horizontal distance shall be 25 percent wider.
* (iii) In Table 4.3.3 values of width of ramps used for ascending and steeper than 1 in 10 slope shall be increased by 10 percent.
**Table 4.3.3: Capacity Factors for Assembly Seating**
| **Number of seats within a single assembly space.** | **Clear Width per Seat Served Steeped aisles (mm)** | **Clear Width per Seat Served Passageways, Ramps and Doorways (mm)** |
| --------------------------------------------------- | --------------------------------------------------- | -------------------------------------------------------------------- |
| ≤ 2,000 | 7.6\_a\_ | 5.6 |
| 5,000 | 5.1\_a\_ | 3.8 |
| 10,000 | 3.3\_a\_ | 2.5 |
| 15,000 | 2.4\_a\_ | 1.8 |
| 20,000 | 1.9\_a\_ | 1.4 |
| ≥25,000 | 1.5\_a\_ | 1.1 |
### 3.8.3
The minimum width of level or ramped aisles shall be as specified below:
* Seats on both sides of the aisle 1.0 m Seats on one side of the aisle 0.9 m
### 3.8.4
The minimum width of stepped aisles shall be as specified below:
* Seats on both sides of the aisle 1.2 m Seats on one side of the aisle 1.0 m
### 3.8.5
The minimum clear gap between rows, measured as the clear horizontal distance between the back of the row ahead and the nearest projection of the row behind shall be 300 mm. For chairs having automatic or self-rising seats, the measurement shall be made with the seats in the raised position, for non-automatic seats the measurement shall be taken with the seats in the down position.
### 3.8.6
For rows of seating served by an aisle or doorway at only one end of the row, the path of travel shall not exceed 10 m from any seat to the aisle or doorway. The minimum clear gap between rows shall be increased beyond 300 mm specified in Sec 3.8.6 by 15 mm for each seat in excess of 7, but the clear gap need not exceed 550 mm.
### 3.8.7
In any assembly occupancy spectators are allowed to wait in the lobby or similar space within the building until seats are available. Exits shall be provided for the waiting spaces on the basis of 0.28 m2 areas per person waiting space and one wheel chair space
for every 100 occupant. Such waiting occupant load shall be added with main assembly load for calculating exit size for the assembly as per provisions of this Code.
## **3.9 Doorways**
One surface of a door leaf which is exposed to a fire incident is the terminal point of exit access and other surface of that said door which is unexposed to that fire incident is the starting point of an exit. A door or an opening protective assembly is an obstruction for occupants to pass through from exit accesses to exits until and unless it is installed as per provisions of this Code.
### 3.9.1
Each occupant of a room or space shall have access to at least one exit door or exit access assembly. The occupant load per exit door and the travel distance up to that door shall not exceed the values specified in Table 4.3.4.
### 3.9.2
Where either the occupant load or the travel distance exceeds the values specified in Table 4.3.4 shall have multiple exit doors to comply the both.
### 3.9.3
The width of a door shall not be less than 1 m and the height shall be not less than 2 m. Exit doors shall be side swing or pivoted of side hinge type.
### 3.9.4
No sliding or hanging door shall be used as a means of exit. In pressurized areas and when occupant load is less than 10, restriction of Sec 3.9.3 may be exempted.
### 3.9.5
All exit access doors shall be of a side-swinging type. When the occupant load exceeds 50 or in a hazardous occupancy, the doors shall swing outward from the room or towards the direction of travel. Swinging of the door shall not constrict the width of the corridor narrower than 0.9 m measured at the most critical position.
### 3.9.6
Exit doorways shall not open directly on a flight of stairway. A clear area which more than the width of the door leaf as specified in the above Sec 3.9.5 shall be maintained immediately outside the doorway. The floor levels shall be same in the direction of travel as per provisions of this Code.
**Table 4.3.4: Maximum Occupant Load and Travel Distance for Spaces with One Exit Door**
| **No.** | **Occupancy** | **Maximum Design Occupant Load** | **Maximum Travel Distance (m)** |
| ------- | ------------- | -------------------------------- | ------------------------------- |
| A | Residential | | |
| C | Institutional | 12 | 23 |
| D | Health Care | | |
| B | Educational | | |
| I | Assembly | | |
| E | Business | 50 | 23 |
| F | Mercantile | | |
| G | Industrial | | |
| H | Storage | 30 | 30 |
| J | Hazardous | 5 | 8 |
### 3.9.7
Revolving doors shall not be used as a means of exit in assembly, educational or institutional buildings or in spaces with an occupant load of 200 or more. In all other cases revolving doors shall not constitute more than half of the total required exit door width and each revolving door with least diameter of 2.7 m shall be credited not more than 50 persons. Exit doors shall be installed in the same wall within proximity of 3m of Revolving doors and shall comply with the following:
#### 3.9.7.1
Revolving doors shall be positioned with a dispersal area at a distance of 3m or more from the foot or top of stairway or escalators or moving walks or lift lobbies.
#### 3.9.7.2
Revolving doors shall stop rotating and stand still in a book-fold position at a force not more than 800 N or when a force is applied not more than 578 N to a wing within 760 mm of outer edge or due to sudden power failure catch automatically released and ready to manual revaluation and that provide a path which shall have aggregate width minimum 910 mm.
#### 3.9.7.3
A manual control switch shall be installed in an approved location.
#### 3.9.7.4
Speed of revolving door shall not exceed the revolution per minute shown below:
| **Inside Diameter (m)** | **Manual-mode Speed limit (rpm)** | **Power-mode Speed limit (rpm)** |
| ----------------------- | --------------------------------- | -------------------------------- |
| 2 | 12 | 11 |
| 2.1 | 11 | 10 |
| 2.3 | 11 | 9 |
| 2.4 | 10 | 9 |
| 2.6 | 9 | 8 |
| 2.7 | 9 | 8 |
| 2.9 | 8 | 7 |
| 3 | 8 | 7 |
#### 3.9.7.5
All exit doors shall be operable without the using a detachable key from the side they serve to evacuate.
## **3.10 Stairways**
Change in level in elevations achieved by steps combination of identical risers and treads as per provisions of this Code shall be termed as Stairway irrespective of their locations. Stairways within an envelope shall be termed as Staircase. Exception: stepped aisles with in an assembly.
Width of Stairways shall be a length perpendicular to the direction of travel, a clear distance measured between inner edges of handrails or a clear distance between inner edges of a handrail of exposed side to its opposite and parallel surface measured at a height of inner edge of cross section of that handrail. In case of variation in width measurement the smallest value shall represent the width of a stairway. Required combination of dimensions for risers and treads given in Table 4.3.5.
Required guards and handrails shall continue for the full length of each flight of stairways. Inner turns of handrail of flights shall be at the landings and grasp ability of handrails shall be smooth and continuous, Handrail Brackets or balusters attached to the bottom surface of handrail shall not be considered to be obstructions to grasp ability. Gap between any surface and handrail shall be not less than 63.5 mm.
Stairways serving more than three storey building having capacity more than 10 occupants shall have visual enclosures to avoid any impediments to stair use by persons having fear of height, any arrangement intended to meet this requirement shall be at least 1070 mm in height.
### 3.10.1
The required width of exit stairways shall be computed in accordance with the provisions of Sec 3.6, but it shall not be less than the minimum widths specified in Tables 4.3.6 and 4.3.7
### 3.10.2
The least dimension of landings or platforms in exit stairways shall not be less than the required width of stairway and shall be leveled, except that the landing between two stair flights in a straight run shall not be required to be wider than 1.2 m in the direction of travel.
When two stair flights are not straight or nonparallel to each other, a turning in the path of travel direction occurred which is other than U turn. Landing width shall be the
required width of stairway and length of the common landing between such flights shall be one tread depth more lengthen when measured from both edges of stairway from both the flights.
**Table 4.3.5: Combination of Risers and Treads**
| Grade (%) | Angle of Flight — Deg | Angle of Flight — (mins) | Tread Depths (mm) | Risers (mm) | Available Headroom Clearance of Flight (mm) | Handrail or Guard Height (mm) | Maximum Number of Flights |
| --------- | --------------------- | ------------------------ | ----------------- | ----------- | ------------------------------------------- | ----------------------------- | ------------------------- |
| 31.25 | 17 | 21 | 406 | 127 | 2159 | 851 | 6 |
| 33.87 | 18 | 43 | 394 | 133 | 2184 | 851 | 6 |
| 37.28 | 20 | 27 | 375 | 140 | 2184 | 851 | 6 |
| 41.07 | 22 | 20 | 356 | 146 | 2184 | 851 | 6 |
| 44.44 | 23 | 58 | 343 | 152 | 2210 | 838 | Unlimited |
| 48.07 | 25 | 40 | 330 | 159 | 2210 | 838 | Unlimited |
| 53.06 | 27 | 57 | 311 | 165 | 2235 | 838 | Unlimited |
| 57.44 | 29 | 52 | 324 | 171 | 2235 | 838 | Unlimited |
| 63.63 | 32 | 28 | 279 | 178 | 2261 | 838 | Unlimited |
| 69.04 | 34 | 37 | 267 | 184 | 2286 | 838 | Unlimited |
| 75 | 36 | 52 | 254 | 190 | 2311 | 838 | Unlimited |
| 81.57 | 39 | 12 | 241 | 197 | 2362 | 851 | Unlimited |
| 88.88 | 41 | 38 | 229 | 203 | 2388 | 851 | Unlimited |
| 97.05 | 44 | 9 | 216 | 210 | 2438 | 851 | Unlimited |
| 103.02 | 45 | 51 | 210 | 216 | 2464 | 851 | Unlimited |
| 107.07 | 46 | 57 | 206 | 222 | 2489 | 864 | 10 |
| 112.5 | 48 | 22 | 203 | 229 | 2515 | 864 | 10 |
* Note: Allowable length of nosing at the outer edge of tread shall not be included in the tread depth measurement. The maximum rise of a single flight between landings shall not be exceeded 3658 mm and in case of large assembly maximum rise of a single flight between landings shall not be exceeded 2438 mm.
**Table 4.3.6: Minimum Width of Stairways in Egress System**
| **No.** | **Occupancy** | **Minimum Width of Each Stairway (mm)** |
| ---------- | --------------------------------------------- | --------------------------------------- |
| A | Residential: A1, A2 | As per Table 4.3.6 |
| | A3, A4, A5 | 1120 |
| B | Educational | |
| | Occupant load up to 130 | 1120 |
| | Occupant load more than 130 but not more 250 | 2235 |
| D | Hospital | |
| | Patient area | 2235 |
| | Staff area | 1120 |
| I | Assembly: I1, I2, I3, I4, I5 | As per provisions of this Code. |
| All others | | As per provisions of this Code. |
* Note: The required number of stairways shall be determined by dividing the calculated total widths of stairways as per sections 3.5, 3.6 and Table 4.3.2 of this Chapter by applicable minimum stair width as specified in this table and any fractions thereof shall be rounded up with the next higher integer. Unit width of stair and multiple even numbers shall be maintained as per provisions this Code.
**Table 4.3.7: Fire Escape Stairs**
| Element | Serving More than 10 Occupants | Serving 10 or Fewer Occupants |
| ------------------------------------------------------- | ---------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------- |
| Clear widths | 560 mm between handrails | 560 mm between handrails |
| Minimum horizontal dimension of any landing or platform | 560 mm | 560 mm |
| Maximum riser height | 230 mm | 230 mm |
| Minimum tread, exclusive of nosing | 250 mm | 250 mm |
| Tread construction | Solid, 13 mm diameter perforation permitted | Solid, 13 mm diameter perforation permitted |
| Winders | Not permitted | permitted subject to Sec 3.10.7 |
| Spiral | Not permitted | permitted subject to Sec 3.10.7 |
| Maximum height between landings | 3.70 m | 3.70 m |
| Headroom, minimum | 2.00 m | 2.00 m |
| Access to protected openings | Door or casement windows, 600 mm x 2000 mm or double-hung windows 70 mm x 900 mm clear opening | Window providing a clear opening of at least 500 mm in width, 600 mm in height, and 0.53 m2 in area |
| Level of access openings | Not over 300 mm above floor; steps if higher | Not over 300 mm above floor; steps if higher |
| Discharge to ground | Swinging stair section permitted if approved by authority having jurisdiction | Swinging stair section permitted if approved by authority having jurisdiction |
| Capacity, number of person | 13 mm per person if access by door; 25 mm per person if access by climbing over window sill | 10 |
Note: The maximum design occupant load for a Fire escape stair shall not be exceeded 50 occupants from any floor level.
### 3.10.3
The rise and tread dimensions in a stairway shall be identical and the headroom requirements shall conform to the provisions of this Code.
### 3.10.4
Handrails height on stair shall be not less than 860 mm and not more than 960 mm above the surface of the tread, measured vertically from the top of the rail to the outer edge of the tread. Peripheral diameter of circular cross section of a handrail shall not be less than 32 mm and not more than 50 mm. Any other shape with perimeter dimension of not less than 100 mm, but not more than 160 mm and with the largest crosssectional dimension not more than 55 mm shall be permitted provided that all edges are rounded to provide a radius of not less than 3 mm. Handrails shall be graspable along their entire length. Additional handrails that are lower or higher than main shall be permitted.
### 3.10.5
The height of guards shall not be less than 105 mm measured vertically from the top of the guards from the surface of adjacent area to be served by them. When blasters are used in the guards rail shall be used to create a pattern as such size that a sphere 100 mm in diameter shall not pass through any opening up to a height of 860 mm. Riser, tread and the bottom rail of guards formed a triangular opening shall not be of such size that a sphere 150 mm in diameter shall not pass through.
### 3.10.6
There shall be no variation in excess of 5 mm in depth of adjacent treads or in the height of adjacent risers, and the tolerance between the largest and smallest tread or between the largest and smallest riser is 10 mm in any flight.
### 3.10.7
Monumental stairs, Circular stairs, Curved stairs, Spirals and winders, stepped and rung ladders, alternate tread devices shall be permitted as per provisions of this Code.
#### 3.10.7.1
When the width of stairways exceeded 4475 mm termed as Monumental or Grand Stairway shall be permitted as per provisions of this Code.
#### 3.10.7.2
Curved stairs or circular stairs shall be permitted as a component of means of egress as per provisions of this Code provided that the depth of tread is not less than 280 mm at a point 300 mm from the narrower end of the tread and the smallest radius is not less than twice of stair widths and shall comply with the provisions of this Code.
#### 3.10.7.3
Spiral stairways shall be permitted where occupant load shall not more than five. For spiral stairways the following conditions shall be applicable:
* (a) The clear width of the stairs shall not be less than 660 mm.
* (b) The height of risers shall not exceed 240 mm.
* (c) Headroom shall be not less than 1980 mm.
* (d) Treads shall have a depth not less than 190 mm at a point 300 mm from the narrower edge.
* (e) All treads shall be identical.
#### 3.10.7.4
Winders shall be permitted in stairs where occupant load shall not be more than three.
* (a) Winders shall have a tread depth not less than 150 mm and a tread depth not less than 280 mm at a point 300 mm from the narrowest edge.
* (b) The clear width of the stairs shall not be less than 660 mm.
#### 3.10.7.5
Stepped ladders and Rung ladders shall be installed with pitch that exceeds 75 degrees as per standards of ANSI A14.3. The lowest rung of any ladder shall not be more than 300 mm above the level of the surface beneath it.
* (a) From towers and elevated platforms around machinery or similar spaces subject to occupancy load not to exceed three persons.
* (b) Open structure, observation towers or railroad signals that are designed for occupancy not more than three persons.
#### 3.10.7.6 Alternate tread device
The occupant load shall not exceed three and shall comply with the followings:
* (a) Handrail shall be provided on both sides of alternate tread device having clear width not less than 430 mm and not more than 610 mm
* (c) Headroom shall not less than 2000 mm and angle of the device shall be between 50 degrees and 68 degrees to horizontal.
* (c) The initial tread of the device shall begin at the same elevation as the platform, landing, or floor surfaces and the alternating treads shall not be laterally separated by a distance more than 50 mm.
* (d) Treads shall have projected depth not less than 150 mm and each tread providing 240 mm of depth, including overlapping of treads.
* (e) The height of the risers shall not exceed 240 mm.
### 3.10.8
Stairways shall have continuous guards on both side along the direction of travel and a continuous handrail shall be provided with inner edge guard. A stair of width more than 1120 mm but not more than 2235 mm shall have guards and handrails on both of the edges. Inner edge handrails shall be continuous and outer edge handrails shall be along the flights extended up to one tread depth on both the landings. A stair the width exceeds 2235 mm; intermediate handrails shall be installed with similar length of outer edge handrail. Single traffic lane shall be calculated 560 mm in the stairway and two traffic lanes shall be 1120 mm. Widths of stairs shall be multiple of two traffic lane other than width specified in the Table 4.3.6.
### 3.10.9
All exit stairways shall be constructed by materials that conform to the fire resistance requirements of the type of construction of the building, except that solid wooden handrails shall be permitted for all types of construction.
### 3.10.10
An exit stairway shall not be built around a lift shaft unless both of them are located in a smoke proof enclosure and made of a material with fire resistance rating required for the type of construction of smoke proof enclosure.
### 3.10.11
Exterior stairways used as fire stair shall not be considered as a component of means of egress, unless they lead directly to the ground or a refuge area, are separated from the building interior by fire resistive assemblies or walls and are constructed by noncombustible materials and free from smoke accumulation.
## **3.11 Ramps**
### 3.11.1
Ramp is a sloping surface steeper than 1 in 20 but not steeper than 1 in 8 used by walkers only. Slope of ramps to comply with accessibility requirement shall not be steeper than 1 in 12.
### 3.11.2
The minimum width of exit ramps shall not be less than that width required for corridors or passages.
### 3.11.3
The slope of an exit ramp shall not exceed 1 in 8, but for slopes steeper than 1 in 10 the ramp shall be surfaced with approved non-slip material or finished such as to effectively prevent slipping.
### 3.11.4
Guards and handrails shall be provided on both sides of ramps having slope steeper than 1 in 15.
### 3.11.5
Ramps shall be straight, in case of changes in the travel direction that shall be made at the level platforms or at the landings except that ramps having a slope steeper than 1 in 12 may be curved at any place.
### 3.11.6
Length of the sloping portion of ramps shall be at least 915 mm but not more than 9150 mm long between level platforms or landings.
### 3.11.7
Level platforms or landings shall be at least as wide as the ramps and shall be placed at the bottom, at intermediate levels where required, and at the top of all ramps. Level platform shall be provided on each side of openings into or from ramps having minimum length of 915 mm in the direction of travel and when a door swings on the minimum length of platform or landing shall be 1525 mm.
### 3.11.8
Doors on ramps shall not be opened on sloping surface shall be complied with the requirements of 3.9 of this Chapter.
### 3.11.9
Sloping or ramp driveway approaching basements or any parking structures shall not be credited as an exit ramp when slope is steeper than 1 in 8 and not complied
with Sec 3.11 of this Chapter. Exits requirement of such basements shall be achieved by stairways or fire lifts within smoke proof enclosure approached by a two doors smoke lock vestibule.
## **3.12 Horizontal Exits**
### 3.12.1
The connection between two separated areas of a building or connection between buildings at same level which the horizontal exit serves shall be provided with at least 2 hour fire resistance rated walls, or by an open air balcony or a bridge having protected openings.
### 3.12.2
The horizontal exits shall be protected from the area of incidence by self-closing fire door.
### 3.12.3
The width of a horizontal exit access door shall not be less than 1 m.
### 3.12.4
Changes in level in the elevation along the direction of the horizontal exit shall not be achieved by single step but by ramps which is not stepper than 1 in 12.
### 3.12.5
Where the horizontal exit serves for only one side, fire door shall swing in along the direction of travel. When horizontal exit serves both the side of separated area, the doors shall have two leaves and each leave dedicated to satisfy direction of travel from assigned area, or there shall be two independent doors assigned for two areas each of them serves only one area. When the building is occupied the doors installed in horizontal exit shall be operable at all times without the use of a detachable key.
### 3.12.6
Horizontal exit relocates occupants to an area which is either a public space or a space used by other occupants and shall be termed as a refuge area. The capacity of the refuge area shall be computed on the basis of net floor area excluding stairways, shafts and spaces allotted to occupants of the receiving end. The required capacity of a refuge area shall be 0.28 m2 per healthy occupant and 0.3 m2 per wheelchair or 2.8 m2 per patients retained in bed for delayed egress or an area equivalent to a passage or a corridor having width to comply the capacity of evacuees and connected with the components of exits up to exit discharge.
## **3.13 Smoke Proof Enclosure**
Any compartment or a room or a control area surrounded by barrier walls within a building structure shall be protected from smoke penetration during a fire incident occurred elsewhere in the building shall be termed as smoke proof enclosure.
A stairway with in an envelope shall be termed as Interior stairway or staircase. Any exterior side having opening of 50 percent or more in such a way that there shall be no smoke accumulation shall be termed as open stair.
### 3.13.1
An interior stairway conforming to Sec 3.10 and having entry from an exterior balcony or through a ventilated vestibule conform a smoke proof enclosure provided no direct opening or any aperture allowed on the walls of the stair from the building side.
### 3.13.2
All exit stairways mentioned above shall be protected by a smoke proof enclosure when serving occupants are located in a high rise building.
### 3.13.3
There shall be provision to access enclosed stairways through vestibule or an open balcony. The minimum width of a vestibule shall be equal to width of connected passages or corridors specified in section 3.7 in this Chapter and the minimum length of a vestibule in the direction of travel shall be 1.8 m.
### 3.13.4
The minimum fire resistance rating of the walls forming a smoke proof enclosure around stairway including the vestibule thereof shall be 4 hours and separated from the area of incidence having no openings other than a fire door for the entry to the vestibule. For fire rating of the door see Chapter 1 Part 3.
### 3.13.5
All doors in smoke proof enclosure and the vestibule shall be self-closing type or they shall be fitted with automatic closing devices actuated by the fire detection system.
### 3.13.6
The vestibule shall have adequate natural ventilation. Each vestibule shall have a minimum area of openings of 2 m2 divided into two in an exterior wall facing a courtyard, street or public way wider than 6 m. The location of one opening measuring 1.5 m2 shall be as high as possible and another shall be 0.5 m2 as low as possible.
### 3.13.7
If the enclosed staircase is windowless, mechanical ventilation shall be installed. If the vestibule is windowless, mechanical ventilation shall also be installed. In addition to ventilation a positive pressure of 50 Pa shall be maintained in the vestibule. This positive pressure must be developed within 30 seconds of the incident of fire. When the staircase and the vestibule are windowless emergency illumination shall be provided.
## **3.14 Number of Exits**
### 3.14.1
The number of exits shall be determined as per provisions of Sec 3.6, Tables 4.3.1, 4.3.2 and 4.3.8 of this Chapter and complying with maximum dead end passage or corridors and maximum travel distance.
### 3.14.2
Total required widths of exits shall be calculated as per provisions of the Tables 4.3.2 and 4.3.8 shall be divided and distributed at a distance not less than one-third of diagonal distance of space and the travel distance and the width of each exit shall comply with the provisions of this Code. The required number of exits in a space as specified below:
| Occupant Load | Minimum Exits |
| ---------------------------- | --------------- |
| Occupant load less than 50 | Minimum 1 exit |
| Occupant load 50 to 500 | Minimum 2 exits |
| Occupant load 501 to 1000 | Minimum 3 exits |
| Occupant load more than 1000 | Minimum 4 exits |
### 3.14.3
High rise buildings having a floor area larger than 500 m2 on each floor used as educational, institutional, assembly, industrial, storage or a mixed occupancy involving any of these or hazardous occupancy, shall have a minimum of two staircases. These staircases shall comply with the requirements as specified in Sec 3.13 of this Chapter.
### 3.14.4
Where two accessible means of egress are required, the exits serving such means of egress shall be located at a distance from one another not less than one-half the length of the maximum overall diagonal dimension of the building or area to be served.
## **3.15 Travel Path**
### 3.15.1
Travel path shall be measured along the center line of a natural and unobstructed path up to center of an exit access door opening. In case of a stairway exist in the travel path shall be measured along an inclined straight line through the center of outer edge of each tread of a stairway.
### 3.15.2
Occupant load and components of exits shall be arranged in such a manner that the travel path from any point in the area served shall not be exceeded as listed in the Table 4.3.8.
### 3.15.3
Unit width shall be 560 mm and fraction of unit width less than 280 mm shall not be credited. Where calculation of total required width give fractional result, next larger integral number of exit units or integral number plus one-half shall be used. Where changes in elevation exist, one-half or less unit of width shall not be permitted.
### 3.15.4
Capacity of exits shall be measured in unit of width of 560 mm and the number of occupants per unit width shall be determined by the occupancy group and type of exits as listed in Table 4.3.8.
### 3.15.5
Wherever more than one exit required in a room or in any floor they shall be placed as remote as possible from each other. As far as practicable, exits shall be arranged in such a manner to provide a refuge area or an exit discharge to the occupants irrespective of the direction of travel from any point in an area served.
## **3.16 Means of Exit Signs and Illumination**
### 3.16.1
All required means of exit or exit access in buildings or areas requiring more than one exit shall be signposted. The signs shall be clearly visible at all times, where necessary supplemented by directional signs. All exit doors shall be clearly marked for easy identification.
Exceptions: Building Occupancy type A.
#### 3.16.1.1
Location: Exit signs shall be installed at stair enclosure doors, horizontal exits and other required exits from the storey. When two or more exits are required from a room or area, exit signs shall be installed to clearly indicate the direction of egress.
Exceptions:
* (i) Main exterior exit doors which obviously and clearly are identifiable as exits need not be signed when approved by the Building Official.
* (ii) Exit signs are not required for buildings of occupancies A1, A2 and individual units of A3.
* (iii) No sign is needed for exits from rooms or areas with an occupant load of less than 50 for Occupancy type C.
**Table 4.3.8: Determination of Exit and Access Requirements.**
| Occupancy Group/Classification | | Maximum Travel Path (meter) — Unsprinklered | Maximum Travel Path (meter) — Full fire resistive or sprinklered | Capacity: Occupancy per unit width — Door openings: To outdoors at Grade | Capacity: Occupancy per unit width — Door openings: All other Exit and corridor doors | Capacity: Occupancy per unit width — Stairs, Escalators | Capacity: Occupancy per unit width — Ramp, Corridors, Exit passageways, Horizontal exit | Ramp, Passage, Corridors — Minimum width (mm) | Ramp, Passage, Corridors — Maximum Dead End (mm) |
| ------------------------------ | ------------- | ------------------------------------------- | ---------------------------------------------------------------- | ------------------------------------------------------------------------ | ------------------------------------------------------------------------------------- | ------------------------------------------------------- | --------------------------------------------------------------------------------------- | --------------------------------------------- | ------------------------------------------------ |
| A1, A2 | Residential | N.R. | N.R. | N.R. | N.R. | N.R. | N.R. | N.R. | N.R. |
| A3, | Residential | 45 | 60 | 50 | 40 | 30 | 50 | 36 | 12190 |
| A4,A5 | Residential | 45 | 60 | 50 | 40 | 30 | 50 | 36 | 12190 |
| B | Educational | 45 | 60 | 100 | 80 | 60 | 100 | 915 | 12190 |
| C1, C2 | Institutional | 38 | 53 | 50 | 40 | 30 | 50 | 915 | 12190 |
| C3, C4, C5 | Institutional | 38 | 53 | 30 | 30 | 15 | 30 | 2440 | 9150 |
| D | Health | 38 | 53 | 30 | 30 | 15 | 30 | 2440 | 9150 |
| E | Business | 60 | 90 | 100 | 80 | 60 | 100 | 1120 | 15240 |
| F | Mercantile | 45 | 60 | 100 | 80 | 60 | 100 | 915 | 15240 |
| G1 | Industrial | 60 | 120 | 100 | 80 | 60 | 100 | 1120 | 15240 |
| G2 | Industrial | 60 | 120 | 100 | 80 | 60 | 100 | 1120 | 15240 |
| H1 | Storage | 30 | 53 | 75 | 60 | 45 | 75 | 915 | 15240 |
| H2 | Storage | 38 | 45 | 75 | 60 | 45 | 75 | 915 | 15240 |
| I | Assembly | 45 | 60 | 100 | 80 | 60 | 100 | 1675 | 9150 |
| J | High Hazard | 15 | 45 | 50 | 40 | 30 | 50 | 915 | N.P. |
Notes:
1. In Hazardous occupancy (occupancy J) Travel Path should be performance based but shall not exceed 15240 mm.
2. N.P. = Not permitted
3. N.R. = No requirement, (except as provided in Table 4.3.5b)
4. Capacity of ramp shall be reduced by twenty five percent when slope is steeper than 1 in 10.
5. Corridors serving classroom area of an educational building. Other corridors shall have a minimum width of 1120 mm.
6. Applies to corridors to patient area. Staff corridors shall have a minimum width of 1120 mm.
#### 3.16.1.2
Graphics: The color and design of lettering, arrows and other symbols on exit signs shall be in high contrast with their background as per NFPA 170. Words on the signs shall be at least 150 mm high with a stroke of not less than 20 mm. For vernacular alphabet and numeric height shall be at least 150 mm with stroke not less than 20 mm.
#### 3.16.1.3
Illumination: Signs shall be internally or externally illuminated by two electric lamps or shall be of self-luminous type. When the luminance on the face of an exit sign is from an external source, it shall have an intensity of not less than 53.8 lux from either lamp. Internally illuminated signs shall provide equivalent luminance.
#### 3.16.1.4
Source of Power: Supply of power to one of the lamps for exit signs shall be provided by the premises wiring system. Power to the other lamp shall be from an on-site generator set which shall be installed in accordance with the provisions of this Code.
#### 3.16.1.5
Floor-level Exit Signs: For floor-level exit signs additional approved low-level exit signs which are externally or internally illuminated, or self-luminous, shall be provided in all interior exit corridors serving guest rooms of hotels in Occupancy A5. The bottom of the sign shall be 150 mm to 200 mm above the floor level. For exit doors, the sign shall be on the door or adjacent to the door with the closest edge of the sign within 100 mm of the door frame.
### 3.16.2
Amusement Building Exit Marking: Approved exit direction marking and exit signs shall be provided. Approved low-level exit signs and directional marking shall be located not more than 200 mm above parallel the walking surface and at the exit path.
### 3.16.3
All exit signs shall be illuminated while in use at night, or during dark periods within the area served, in accordance with the provisions of this Code.
### 3.16.4
The means of exit and exit access in buildings requiring more than one exit shall be equipped with artificial lighting. The lighting facilities shall satisfy the provisions of this Code.
# Chapter 4: Equipment and In-Built Facilities Standards
Source: https://docs.sayed.app/bnbc/part-4-fire-protection/chapter-4-equipment-and-in-built-facilities-standards
sign shall be on the door or adjacent to the door with the closest edge of the sign within 100 mm of the door frame.
### 3.16.2
Amusement Building Exit Marking: Approved exit direction marking and exit signs shall be provided. Approved low-level exit signs and directional marking shall be located not more than 200 mm above parallel the walking surface and at the exit path.
### 3.16.3
All exit signs shall be illuminated while in use at night, or during dark periods within the area served, in accordance with the provisions of this Code.
### 3.16.4
The means of exit and exit access in buildings requiring more than one exit shall be equipped with artificial lighting. The lighting facilities shall satisfy the provisions of this Code.
## **4.1 Scope**
The provisions of this chapter shall control standards of the design, installation and maintenance of equipment and in-built fixed, localized, portable facilities required for firefighting within a building and its premises. The regulations of this chapter shall be applicable for all buildings and the provisions stated herein shall not cover the firefighting requirements outside the building premises.
### 4.1.1
Extinguishing agents can be water, dry sand, ash, inert gas, dry chemical, and wet chemicals or mixed in nature of approved type. Agents will be selected as per the area have to extinguished.
### 4.1.2
The gaseous system shall be only used where water or foam cannot be used for fire extinguishing because of the special nature of the contents within the building or areas to be protected.
### 4.1.3
Fixed type fire protection system means there shall be a pipe circuit to cover full or part of a building and extinguishing agents supplied from a point. Localized fixed system means the system will cover a confined space with a self-extinguishing device fitted with a container ready to discharge automaticity. Portable type means the extinguishers can be hand carried in the site of incidents.
### **4.1.4 Fire Classification**
| Fire class A: | Fire involving common combustibles such as wood, paper, plastics,
clothes etc. |
| ------------- | ----------------------------------------------------------------------------------------- |
| Fire class B: | Fire involving flammable liquids and gases, such as gasoline, propane,
and solvents. |
| Fire class C: | Fire involving live electrical equipment such as computer, fax machine
etc. |
| Fire class D: | Fire involving combustible metals such as magnesium, lithium,
aluminum etc. |
| Fire class K: | Fire involving cooking media such as cooking oils and fats. |
## **4.2 Fixed Type Fire Hydrant System**
General area of application shall be Fire class A. Fixed type fire hydrant system comprises of, stand pipes and hose or reel pipes, sprinklers, drenchers or similar devices in appropriate combinations of these and capable of discharging water in an area which to be extinguish.
### **4.2.1 Water Quantity for Fire Protection**
The required flow rate and duration of water for sprinkler or stand pipe system use within the building according to their occupancy classification shall be in accordance with Table 4.4.1 and size of pipes shall be as per provisions of this Code or on the basis of the hydraulic design of the system to maintain flow rate and duration of water discharge.
### **4.2.2 Water Sources for Fire Protection**
Flow rate and duration of discharging water required for interior fire extinguishment of a building shall be supplied from one or any combination of the following sources.
**Table 4.4.1: Fire Protection Flow Requirements**\*
| **Building Type**\*\* | **Sprinkler System (litre/min.)** | **Standpipe and Hose System (litre/min.)** | **Duration in Minutes for Heights Up to 51 m** | **Duration in Minutes for Heights 51 m to 102 m** | **Duration in Minutes for Heights Above 102 m** |
| --------------------- | --------------------------------- | ------------------------------------------ | ---------------------------------------------- | ------------------------------------------------- | ----------------------------------------------- |
| Light hazard- I | 1000 | 1000 | 30 | 38 | 45 |
| Light hazard- II | 1900 | 1900 | 50 | 62 | 75 |
| Ordinary hazard- I | 2650 | 1900 | 75 | 95 | 112 |
| Ordinary hazard-II | 3200 | 1900 | 75 | 95 | 112 |
| Ordinary hazard-III | 4800 | 1900 | 75 | 95 | 112 |
| **Notes:** | | | | | |
* See also Sec 4.2.2.3.
* \*\* Values will be for one riser serving floor area of 1000 m2 .
* Light hazard-I : Occupancy groups, A1, A2, A3, E1 Light hazard-II : Occupancy groups, A4, A5, B, C, D,E2, E3, I2, I4, F1 Ordinary hazard-I : Occupancy groups, I1, I3, I5, F2, F3, G1 Ordinary hazard- II : Occupancy groups, G2 , H1 Ordinary hazard- III : Occupancy groups, H2 Extra hazard : Occupancy group J-pressure and flow requirement for this group shall be determined by Fire Department but shall not be less than required value for Ordinary hazard- III
#### 4.2.2.1 Direct connection to water main
For continuous water supply (public water supply system or private system) with sufficient quantity and pressure to feed and discharge firefighting equipment during peak demand period, direct connection of firefighting system to the water main may be adopted, Figure 4.4.1. In this case guidelines specified in NFPA 22 are to be followed.
![Typical diagram for standpipe and hose system connected directly to the water main]()
#### 4.2.2.2 Roof gravity tanks
Any elevated structure holding a water reservoir or water tank or in any level within a building and having downward supply pipelines shall be termed as gravity tank only when a water reservoir located on a roof of a building shall be termed as roof gravity tank.
For water supply system with inadequate quantity or pressure during peak demand period but with sufficient pressure to feed roof tank, a roof gravity tank may be provided. In that case any one of the following steps shall be followed.
* (a) If only the static height of the roof gravity tank is used to feed and discharge the firefighting equipment, the height of the roof gravity tank from the top floor must be sufficient to create minimum required pressure at the top floor hydrant point. The minimum pressure at hose outlet for standpipes supplying a 50 mm or larger hose shall be at least 300 kPa. This minimum pressure for standpipe system supplying first aid hose (38 mm nominal) shall be at least 200 kPa. This minimum pressure for combination of sprinkler and hose pipe system shall be 600 kPa. To maintain the above required pressure the vertical distance of the roof gravity tank from the top floor hydrant point shall be at 31 m, 20.5 m and 62 m respectively, Figure 4.4.2.
* (b) If the vertical distance between the roof gravity tank and the top floor hydrant point cannot be maintained for gaining required pressure and discharge, fire pump of required size and number shall be installed with standard manufacturer recommended suction and delivery connections, Figures 4.4.3 and 4.4.4.
![Typical diagram showing required static head of gravity roof tank with adequate domestic and fire reserve]()
#### 4.2.2.3 Storage tank
In absence of public water supply system, the building premises shall have individual water sources specified in Part 8. For water supply system, to feed and discharge by firefighting equipment, the building premises may have deep tube well with required flow, water wells, natural water sources or a ground (or underground) tank, roof top tank, swimming pools etc. The capacity of these facilities shall be sufficient to satisfy the flow requirement as specify in Table 4.4.1.
#### 4.2.2.4 Water supply test
After installation of the hydrant system, a flow test shall be conducted to verify the capacity of the discharge system such that the installation can fulfill the minimum capacity (flow and time) as specified in Table 4.4.1. This system shall be periodically inspected, maintained and tested in accordance with NFPA 25.
#### 4.2.2.5 Fire pump
The firefighting equipment shall be directly feed by automatic main fire pump. Centrifugal pump, turbine-type pump (submerged or with vertical shaft) or positive displacement pumps with adequate supply pressure and flow capacity shall be used for water supply during demand. Centrifugal pumps shall not be used where a static suction lift is required.
Once the pump starts, it shall run continuously until stopped manually. The pump shall be fully operational within 30 seconds after starting. There shall be provision for manual
starting where priming is necessary. Automatic priming equipment is necessary to ensure priming at all times. The fire pump shall not be used for other purpose.
Fire pumps shall have the rated capacities as shown in Table 4.4.2. The pump shall be rated at net pressure of 272 kPa or more as per requirement of the firefighting system demand. For pump installation procedure and fittings NFPA 20 shall be followed.
The pump shall be housed in a readily accessible position in a building of noncombustible construction. The pump shall be adequately protected against mechanical damage.
There shall be a provision for secondary fire pump which can be operated by a dedicated diesel engine or by an alternate power supply source with adequate control system and incompliance with safety operation during fire. Quality of the pump assembly shall comply with the specification of International Association of Fire.
![Typical diagram for gravity roof tank with adequate domestic and fire reserve with fire pump on the roof]()
### **4.2.3 Design Considerations for Standpipe and Hose System**
#### 4.2.3.1
The fire protection system shall be designed for their effective use either by amateur or trained firefighting personnel or both.
#### 4.2.3.2
All standpipes in standpipe system shall be sized so that they will provide a minimum flow specified in Table 4.4.1. In standpipe system with more than one standpipe, the supply piping shall be sized for the minimum flow specified in Table 4.4.1 for the first standpipe plus 1000 litre per minute for each additional standpipe. The total number of such additional standpipes shall not be more than 8. All standpipe risers shall be interconnected through check valves of equivalent size to prevent recirculation.
![Typical diagram for gravity roof tank with adequate domestic and fire reserve with fire pump at the ground level]()
#### 4.2.3.3
The minimum pressure for standpipes supplying a 50 mm or larger diameter hose shall be at least 300 kPa. For standpipe supplying first aid hose (38 mm nominal diameter) may have a minimum pressure of 200 kPa. The maximum pressure at any point of the system shall not exceed 2434 kPa, if the hose connection at 40 mm diameter outlet exceeds 700 kPa approved pressure regulating device shall be installed to maintain the above maximum limits.
#### 4.2.3.4
Diameter of the standpipe termed as size shall comply with flow and capacity requirement of the pump shown in Table 4.4.2 or hydraulically design to provide required flow and pressure at the topmost hydrant point.
**Table 4.4.2: Fire Pump Data**
| **Pump Rating (litre/min (gpm) Discharge)** | **Minimum Pipe Sizes Nominal (mm(inch))** |
| ------------------------------------------- | ----------------------------------------- |
| 946 (250) | 75 (3) |
| 1136 (300) | 100 (4) |
| 1514 (400) | 100 (4) |
| 1703 (450) | 125 (5) |
| 1892 (500) | 125 (5) |
| 2839 (750) | 150 (6) |
| 3785 (1000) | 150 (6) |
| 4731 (1250) | 200 (8) |
| 5677(1500) | 200(8) |
#### 4.2.3.5
The water supply required for combined system (for partial automatic sprinkler and Fire Department hose) shall be calculated in accordance with Table 4.4.1 plus an amount equal to the hydraulically calculated sprinkler demand.
#### 4.2.3.6
The system for firefighting purpose may be designed with automatic fire pump with water tank at the ground as shown in Figure 4.4.5.
#### 4.2.3.7
The water stored in storage tank for firefighting operation shall not be used for other purposes. Accordingly, separate water connections should be provided as shown in Figure 4.4.6.
![Typical diagram for fire protection with ground tank and automatic fire pump]()
![Typical diagram for storage tank (ground or overhead) with domestic and fire reserve]()
#### 4.2.3.8
The ground storage tank shall be easily accessible to fire engine of Fire Department. In absence of space available for fire engine, the cover slab of ground storage tank shall be designed to withstand a vehicular load of local fire engine.
#### 4.2.3.9
The standpipe shall be located such as intermediate stair landing, vestibules or nearby in noncombustible enclosure such that it will be able to provide hose stream to the most remote area of the floor served.
#### 4.2.3.10
The hose shall be connected to the standpipe within a height not more than 1.5 m from the finished floor level. The hose stations shall be easily accessible for inspection and testing.
#### 4.2.3.11
The hose connection to a standpipe for large stream shall be at least 100 mm nominal and that of small stream may be 63 mm or 50 mm on each point. The size of first aid hose shall be 38 mm nominal. The hose length shall not be more than 30 m.
#### 4.2.3.12
Different piping materials and fittings for standpipe system presented in Tables 4.4.3 and 4.4.4 shall conform to the standard or one of the standards cited against them. The standard requirements for other materials not provided in these tables shall be subject to the approval of the Authority.
**Table 4.4.3: Piping for Standpipe System**
| **Material** | **Standard** |
| ----------------------------------- | ------------------------------ |
| Copper Tube | ASTM B75, ASTM B88 |
| Copper and Copper-Alloy Tube | ASTM B251 |
| Steel Pipe | ASTM A55, ASTM A120, ASTM A135 |
| Wrought Steel or Iron | ANSI B36.10 |
| **Table 4.4.4: Standpipe Fittings** | |
| **Material** | **Standard** |
| -------------- | ------------------------------ |
| Cast Iron | ANSI 616.1, ANSI B16.4 |
| Copper | ANSI B16.18, ANSI B16.22 |
| Malleable Iron | ANSI B16.3 |
| Steel | ANSI B16.5, ANSI B16.9, ANSI |
| | B16.11, ANSI B16.25, ASTM A234 |
#### 4.2.3.13
The standpipe riser shall be supported at the top and at the lowest level. The riser shall also be provided with support at the alternate level in between top and bottom level of the standpipe riser. The support shall be of adequate strength to support the water-filled pipe load and an additional load of 110 kg.
#### 4.2.3.14
The horizontal standpipe shall have hangers with a spacing not more than 5 m. The hanger shall be able to carry a load of five times the weight of the water-filled pipe and an additional load of 110 kg.
#### 4.2.3.15
There shall be Siamese connection also termed as firemen connection to the standpipe or to the delivery pipe of the gravity roof storage tank. The location of Siamese connection shall be easily accessible from the street or means of access.
#### 4.2.3.16
The system shall be provided with adequate drainage piping to discharge under pressure. The drain pipe shall not discharge into sanitary sewer.
#### 4.2.3.17
All control valves shall be designed to withstand the pressure specified in Sec 4.2.3.3
### **4.2.4 Wet Riser**
A wet riser is a vertical pipe of not less than 100 mm internal diameter, kept permanently charged with water which is then immediately available for use on any floor in the building at which a hydrant or landing valve is provided. The riser is connected to a booster pump or town main of suitable capacity so that they are capable to supply four 13 mm jet at 2.5 bars at the highest outlets.
### **4.2.5 Down Comer**
A similar function to that of wet riser is performed by down comer which like a wet riser is constructed of vertical piping, with outlets at different levels, but is supplied with water from a tank in the roof through terrace pump, gate valve and non-return valve. It is also fitted with inlet connections at ground level and air release valve at roof level for being capable of charged with water by pumping from fire engines.
### **4.2.6 High Velocity Water Spraying Projector System**
This system applies water in the form of conical spray consisting of droplets of water traveling at high velocity. The three principles of extinguishments are employed, namely emulsification, cooling and dilution. While the water droplets are passing through the flame zone, some of the water is turned into steam, diluting the oxygen feeding the fire. Addition of water to the burning oil also cools it and reduces the rate of vaporization. In addition to this droplets of water traveling at high velocity bombard the surface of the oil to form an emulsion of oil and water that will not support combustion.
### **4.2.7 Water Mist Technology**
Fine water spray suppression system can extinguish fires using water and nitrogen from air. Nozzle is used to atomize water by nitrogen or other suitable media to generate mist or fog of finely controlled water droplets. The system operates at low pressure and produces droplets in a range of 80 to 200 microns. These droplets extinguish fire rapidly and efficiently even those involving highly volatile hydrocarbons. This system is an alternative to Halon and other gaseous system in many applications.
### **4.2.8 Drenchers**
Drenchers are used for the external protection of the building against exposure hazard, or radiant heat. Drencher heads are similar to sprinkler heads and may be sealed or unsealed. Drenchers are of three types, roof drenchers, wall drenchers, window drenchers.
### **4.2.9 Dry Riser System**
Dry riser stand pipe system shall be an equivalent alternative of wet riser stand pipe system. The water supply for an automatic or semi-automatic standpipe system shall be designed such that the system must be capable of supply the system during peak demand hour.
### **4.2.10 Design Consideration of Sprinkler System**
#### 4.2.10.1
A system of water pipes fitted with sprinkler heads as per manufacturers specification may be installed actuate automatically, control and extinguish a fire by the discharge of water.
#### 4.2.10.2
The pipe schedule sizing to supply different number of sprinklers for their different uses may be in accordance with Tables 4.4.5 and 4.4.6
#### 4.2.10.3
Each sprinkler shall serve a maximum ceiling area specified in Table 4.4.7 for different types of building according to their uses.
#### 4.2.10.4
Water supply piping and fittings for sprinkler system shall conform to the standard or one of the standards cited against them in accordance with Tables 4.4.4 and 4.4.8. The standard requirements for other pipe materials not provided in these tables shall be subject to the approval of the Authority.
#### 4.2.10.5
The sprinkler system shall be provided with adequate support or made flexible to prevent pipe breakage during earthquake.
#### 4.2.10.6
The hanger in sprinkler system shall be designed to carry a load equal to five times the weight of the water-filled pipe plus an addition load of 110 kg. The support shall be designed to support a load equal to the weight-filled pipe plus and additional load of 110 kg.
### **4.2.11 Connection**
#### 4.2.11.1
There shall be Siamese connection to the sprinkler system located outside the building and accessible to the fire department connection.
#### 4.2.11.2
All risers shall be connected through a gate valve with a main of size equal to that largest riser.
#### 4.2.11.3
The sprinkler system shall be provided with adequate drainage arrangement. The drain pipe shall not discharge into sanitary sewer.
#### 4.2.11.4
All control valves and fittings shall be able to withstand the pressure specified in Sec 4.2.3.3.
### **4.2.12 Inspection, Testing and Maintenance**
#### 4.2.12.1 Inspection
All piping and equipment shall be inspected for satisfactory supports in accordance with Sec 6.15 in Part 8 of this Code and protection from damage and corrosion. All outlets shall be free from obstruction.
**Table 4.4.5: Size of Water Supply Steel Pipe to Sprinklers**
| **Pipe Size mm**
**(inch) nominal** | **No. of**
**Sprinkler for**
**Light Hazard**\* | **No. of Sprinkler**
**for Ordinary**
\*\*Hazard \*\*\* | **No. of Sprinkler for**
\*\*Ordinary Extra Hazard \*\*\* |
| ---------------------------------------- | --------------------------------------------------------- | ----------------------------------------------------------------- | -------------------------------------------------------------- |
| 25(1) | 2 | 2 | 1 |
| 32(1¼) | 3 | 3 | 2 |
| 38(1½) | 5 | 5 | 5 |
| 50(2) | 10 | 10 | 8 |
| 63(1½) | 30 | 20 | 15 |
| 75(3) | 60 | 40 | 27 |
| 88(3½) | 100 | 65 | 40 |
| 100(4) | NL\*\* | 100 | 55 |
| 125(5) | - | 160 | 90 |
| 150(6) | - | 275 | 150 |
| 200(8) | - | 400\*\*\* | 225\*\*\* |
* Definitions of these terms are given in Table 4.4.1.
\*\* No limit.
\*\*\* One sprinkler system riser or combined system riser shall serve the floor area not more than 4850 m2 for light and ordinary hazardous occupancy and 2325 m2 for extra hazardous occupancy
**Table 4.4.6: Size of Water Supply Copper Pipe to Sprinklers**
| **Pipe Size**
**mm (inch)**
**nominal** | **No. of Sprinkler**
**Connection for Light**
**Hazard**\* | **No. of Sprinkler**
**Connection Ordinary**
\*\*Hazard \*\*\* | **No. of Sprinkler**
**Connection Ordinary**
\*\*Extra Hazard \*\*\* |
| ------------------------------------------------- | -------------------------------------------------------------------- | ------------------------------------------------------------------------ | ------------------------------------------------------------------------------ |
| 25(1) | 2 | 2 | 1 |
| 32(1¼) | 3 | 3 | 2 |
| 38(1½) | 5 | 5 | 5 |
| 50(2) | 12 | 12 | 8 |
| 63(1½) | 40 | 25 | 20 |
| 75(3) | 65 | 45 | 30 |
| 88(3½) | 115 | 75 | 45 |
| 100(4) | NL\*\* | 115 | 65 |
| 125(5) | - | 180 | 100 |
| 150(6) | - | 300 | 170 |
| 200(8) | - | \*\*\* | \*\*\* |
* Definition of these terms is given in Table 4.4.1.
* \*\* No limit.
* \*\*\* One sprinkler system riser or combined system riser shall serve the floor area not more than 4850 m2 for light and ordinary hazard occupancy and 2325 m2 for extra hazard occupancy
**Table 4.4.7: Ceiling Area for a Sprinkler**
| **Construction Type** | **Light Hazard Protected area ft² (m²)** | **Light Hazard Spacing (Max) ft (m)** | **Ordinary Hazard Protected area ft² (m²)** | **Ordinary Hazard Spacing (Max) ft (m)** | **Extra Hazard Protected area ft² (m²)** | **Extra Hazard Spacing (Max) ft (m)** |
| --------------------------------------------------------------------------- | ---------------------------------------- | ------------------------------------- | ------------------------------------------- | ---------------------------------------- | ---------------------------------------- | ------------------------------------- |
| Roof or Floor on Trusses,
Girders or Beam
With High Piling \*\*\* | 200 (18.6) | 15 (4.6) | 130 (12.1) | 15 (4.6) | 100 (9.3) | 12 (3.7) |
| Open Wood Joists
With High Piling \*\*\* | 225 (20.9) | 15 (4.6) | 130 (12.1) | 15 (4.6) | 100 (9.3) | 12 (3.7) |
| Other Type of
Construction
With High Piling \*\*\* | 168 (15.6) | 15 (4.6) | 130 (12.1) | 15 (4.6) | 100 (9.3) | 12 (3.7) |
* Maximum distance in m between sprinklers and between line of piping.
* * The definitions of these terms are given in Table 4.4.1.
* \*\* \* Storage facilities which permit closely piled materials over 4.5 m or materials on rack over 3.6 m.
**Table 4.4.8: Piping for Sprinkler System**
| **Material** | **Standard** |
| ----------------------- | ------------------------------------------ |
| Copper and Copper-Alloy | ASTM B32, ASTM B75, ASTM B88, ASTM B25, |
| | ANSI B36 |
| Steel | ASTM A53, ASTM A120, ASTM A135, ASTM A795 |
#### 4.2.12.2 Testing
Fire protection plumbing system or part thereof shall be tested and approved after installation by the Authority.
* (a) Testing of Standpipe System: The hydrant pipes shall be hydraulically tested to a pressure 1400 kPa or 150% of working pressure whichever is the higher for 2 hours without any leakage at any points. The system shall be able to maintain
above test pressures. The system shall also be tested for the required flow at the highest outlet.
* (b) Testing of Sprinkler System: This system shall be tested for at least 2 hours for a pressure of 1000 kPa or at 350 kPa in excess of normal working pressure when normal working pressure will be more than 650 kPa. The system shall be able to maintain above test pressures. The system shall also be tested for the required flow at the highest outlet.
* (c) Testing of Sprinkler System Pump: The pump used for sprinkler system firefighting purpose shall be tested by approved authority for their performance characteristics and this test report must be submitted at the time of supply of pump. The pump shall be retested or repaired to its original condition if their performance characteristics fall below more than 10 percent of the supplier's test characteristic curve or as specified for the fire protection water supply system.
#### 4.2.12.3 Maintenance
The system shall be maintained for safe operating conditions and tested at least once a year.
## **4.3 Fixed Installation Other Than Water**
Other than water there are different types of fixed installation. These are of mainly two types. (a) Centrally fixed, (b) locally fixed.
### **4.3.1 Centrally Fixed Installation Discharging Extinguishing Agent other than Water**
#### 4.3.1.1 General
This installation can be of two types, one for zone coverage and the other for total coverage. For these system pipe circuits and exhaust manifold are required and shall have special discharging Alarm distinctly different than fire alarm. These fixed installations can be of different types, such as (a) Foam installation, (b) Vaporizing liquid installation, (c) Dry powder installation. (d) Gaseous installation (e) Dry chemical installation (f) Wet chemical installation.
#### 4.3.1.2 Foam installation
Foam extinguishing system shall be of an approved type and shall be installed in accordance with the specification of the manufacturer. The foam extinguishing system is designed to discharge fire suppressive foam concentrates over the area to be protected.
* (a) There are different types of foam installation, such as (i) Pump operated mechanical foam installation, (ii) Self-contained pressurized installation, (iii) Pre-Mixed Foam installation, (iv) High Expansion Foam installation.
* (b) A foam extinguishing system shall be automatically actuated during a fire with provision of manual actuation.
* (c) Warning sign and discharge alarm system shall be provided with the foam extinguishing system, which shall be actuated during the use of the system.
* (d) The system provides protection of boiler rooms with its ancillary storage of furnace oils in basement and other areas where hazardous liquids are stored.
#### 4.3.1.3 Vaporizing liquid installation
Liquefied compressed Halogenated hydrocarbon is fed through distribution pipe works and specially designed discharged nozzles to the area need to be extinguished. Upon discharge the liquid immediately vaporized to form a heavy vapour which achieves very rapid extinction.
There are two types of Vaporizing liquid installation, such as total flooding system and Local application system. This system shall be installed in accordance with the specification of the manufacturer. Safe guards are necessary to prevent injury or death of personnel in area where the atmosphere may be made hazardous by the discharge.
#### 4.3.1.4 Dry powder installation
Dry powder of certain chemicals installation consist of pipe work and discharge nozzle and pressuring media. This installation can be operated automatically or manually. This can be designed for total coverage and for zone coverage.
Dry powder is a range of chemical agents available as extinguishing media. They are used on various flammable liquids where they are confined. This system shall be installed in accordance with the specification of the manufacturer.
#### 4.3.1.5 Gaseous installation
* (a) General: Gaseous extinguishing system shall be of an approved type and shall be installed as per provisions of this Code. The system supplies gas from a pressurized vessel through fixed pipes and nozzles.
* (b) The system is used where water or foam cannot be used for fire extinguishing because of the special nature of the contents within the building or areas to be protected.
* (c) The system shall be automatically actuated and shall be equipped with manual actuation devices as well.
* (d) Warning signs and discharge alarm shall be provided where persons are likely to be trapped in an area made hazardous due to discharge of extinguishing gases.
* (e) Halocarbon agents and inert gas system: Any approved Type of Halocarbon agents are chemicals in the liquid form at high pressure and vaporize readily leaving no residue. These are primarily to protect hazardous fire in enclosed room, vaults, machines, containers, storage tanks, engines, unattended computer server rooms, electrical appliances, liquid gas storage etc. Some example of these chemical is dichlorodifluoro ethane, chlorodifluoro methane. Inert gas system is also an alternative of Halocarbon agents. These are nitrogen and argon in pure form or in mixer at different proportion. These gases are identified as clean total folding fire suppression agents. They are stored in high pressure gas cylinders.
#### 4.3.1.6 Dry chemical extinguishing system
* (a) General: Dry chemical extinguishing system shall be of an approved type and shall be installed in accordance with the provisions of this Code and manufacture's instruction.
* (b) The system shall be automatically actuated during a fire and shall be equipped with manual actuation device as well.
* (c) Warning signs and discharge alarm shall be provided where persons are likely to be exposed to chemical discharge. Chemical agents of the system shall be nontoxic.
#### 4.3.1.7 Wet chemical extinguishing system
* (a) A wet chemical system is a solution of water and potassium carbonate or acetate based chemical which forms the extinguishing agent. The system shall be installed in accordance with the provisions of this Code and manufacturer's installation instruction.
* (b) The system shall be automatically actuated during a fire and shall be equipped with manual actuation device as well.
* (c) In case of wet chemical extinguishing system, label of the approved agent shall be affixed.
* (d) Warning signs and discharge alarm shall be provided where persons are likely to be exposed to wet chemical discharge.
### **4.3.2 Localized Fixed**
Containerized extinguishing agent are available in different shapes and size to be placed in different locations those are prone to fire hazard as for example at the top of cookers in the kitchen, electric connection box etc. Use of these containers shall be approved type and installation shall be as per specification of the manufacturer.
## **4.4 Portable Fire Extinguisher**
### 4.4.1
Portable fire extinguishers shall readily available in different type. These are portable fire extinguisher are of carbon dioxide types, dry chemical types, water types, and Halon types, film-forming type, foam types and Halon carbon type. For proper operation persons with adequate knowledge and familiar with their operation must be available.
### 4.4.2
In accordance with the occupancy hazard, specification of the manufacturer and guide line set by NFPA 10, the minimum number of portable fire extinguishers for different class of fire shall be ascertained. As for example where the floor area of a building is less than 279 m2 at least one fire extinguisher of the minimum size is recommended for Fire Class A.
### 4.4.3
Portable fire extinguishers shall be fully charged, operable at any time and conspicuously located where they will be readily accessible. Portable fire extinguishers shall not be obstructed or obscured from view. In large rooms, means shall be provided to indicate the extinguisher location.
### 4.4.4
Portable fire extinguishers shall be adequately protected from impact, vibration, and adverse environment and shall not be exposed to temperatures outside the listed temperature range shown on the fire extinguisher label.
### 4.4.5
Portable fire extinguishers mounted in cabinets or wall recesses shall be placed so that the fire extinguisher operating instructions face outward. The location of such fire extinguishers shall be marked conspicuously.
### 4.4.6
The owner or designated agent or occupant of a property in which fire portable extinguishers are located shall be responsible for inspection, maintenance, and recharging. The procedure for inspection and maintenance of fire extinguishers varies
considerably. Monthly "quick check" or inspection in order to follow the inspection procedure as outlined in NFPA 10 shall be done.
### 4.4.7
Maintenance, servicing and recharging shall be performed by trained persons having available the appropriate servicing manual(s), the proper types of tools, recharge materials, lubricants, and manufacturer's recommended replacement parts or parts specifically listed for use in the fire extinguisher. These extinguishers shall be maintained as per NFPA 10, at intervals of not more than one (1) year.
### 4.4.8
All rechargeable-type fire extinguishers shall be recharged after any use or as indicated by an inspection or when performing maintenance or as per the recommendations of the manufacturer.
### 4.4.9
For personal safety during approach with extinguishing equipment it shall be remembered that most fires produce toxic decomposition products of combustion and some materials can produce highly toxic gases. Fires can also consume available oxygen or produce dangerously high heat. All of these can affect the degree to which a fire can be safely extinguished.
### 4.4.10
All extinguishing agents other than clean agents shall be approved by the authorities having jurisdiction.
## **4.5 Rate of Water Flow For Fire Protection In Tall Building**
High rise building exceeding 80 meter height shall be termed as Tall Building. The quantity, sources and mode of water supply in tall building shall be in accordance with Sec 4.2. In high rise buildings fittings and equipment for firefighting may be subject to excessive pressure.
Pressure on firefighting equipment in Tall building shall be reduced by dividing the building into different zones. In this process the building shall be divided into different water supply zones so that the firefighting equipment will serve within their maximum allowable limit of pressure. Separate automatic fire pump or combination of tank and automatic pump shall be installed for supplying water to the firefighting equipment in each zone as per Figures 4.4.7 and 4.4.8.
## **4.6 Fire Detection and Alarm System**
### **4.6.1 Fire Detection Shall be Done by the Following Ways**
(a) Human surveillance:
Human surveillance shall be acceptable where the user and occupant are capable of maintaining surveillance for detecting fire and smoke when a person appointed and assigned to detect fire shall be termed as Fire watch.
(b) Automatic smoke or/and heat detection :
The installation of automatic fire and smoke detection system shall be a necessity when the size, arrangement and occupancy of a building become such that a fire itself cannot provide adequate warning to its occupants.
The automatic fire and smoke detection system shall include, spot or line type heat sensitive detectors and optical, ionized or chemical sensitive type of smoke detectors.
(c) Video surveillance :
Cameras capable of registering and transmitting real time images in to a monitoring device having display commonly termed as CCTV shall be installed systematically to cover an area for detecting any incision of smoke and fire. This CCTV will remain under either human surveillance or monitored by compatible software to transmit signal automatically to the fire alarm system and also to the authorized persons.
### **4.6.2 Fire Alarm System**
#### 4.6.2.1
In a fire incident, panic management shall be the prime concern for a successful relocation, delayed egress or evacuation of occupants from a building structure. Activation of alarm shall be sequential and compatible with all design scenarios. Means of egress system is so designed that all alarms of a building shall not be activated at a time. A general announcement of fire shall be done for the occupant or the word “Fire” shall be avoided but authorized persons responsible for evacuation shall be alerted through Password or Pass Phrase. As per design scenarios a systemic execution protocol shall be developed where a building shall be sub-divided into zones for installation alarms and for fight in place, relocation of occupants, delayed egress or immediate evacuation.
Alarm system can be of different types, such as audible alarm, visual alarm, vibration alarm, and display alarm.
* (a) Audible alarm: Ringer, bell, horn, chime and voice command via public address system (PA system) are the examples of audible alarm system.
* (b) Visual Alarm: A bright white light emitting device with specific intensity and cycle of emission is capable to draw attention of a person having limited hearing shall be termed as visual alarm. A visual alarm shall be installed where a person working alone in a room or a space having hearing limitations. In a public place or in any place more than two persons are present and one having normal hearing ability shall not require to install visual alarm.
* (c) Vibration Alarm: Alarm activated through vibration can be used for alarm.
* (d) Display Alarm: Textual, graphical or pictorial display on screens or monitors can be used as alarm.
![Typical diagram for fire protection in different water supply zones of a tall building with separate fire pump per zone]()
![Typical diagram for fire protection in different water supply zones of a tall building with intermediate tanks]()
#### 4.6.2.2
Each floor shall be separated as zone for the purpose of alarm annunciation.
#### 4.6.2.3
A floor is subdivided by fire or smoke barriers and allows relocation of occupants from area of incident to another area on the same floor each area shall be considered as a zone and annunciated separately for the purpose of alarm location.
#### 4.6.2.4
Notification zones shall be consistent with emergency response or evacuation plan for the protected premises. The boundaries of notification zones shall be coincident with building peripheral walls, fire or smoke compartment boundaries, floor separations or other fire safety subdivisions.
#### 4.6.2.5
If required by the authorities having jurisdiction, the alarm system be allowed the application of alarm signal to one or more zones at the same time, shall allow voice paging to the other zones or in any combination.
#### 4.6.2.6
Alarm annunciation at the fire command center shall be by means of audible and visible indicators.
#### 4.6.2.7
Activation of fire extinguishment system shall have a supervisory alarm. An automatic extinguishment system capable of discharging other than water extinguishing agents shall have dedicated and distinct alarm system and shall be actuated before discharging such agents.
## **4.7 Related Appendix**
Appendix C Detail Guidelines for Selection and Sitting of Fire Detection System
# Chapter 5: Requirements For Fire Detection and Extinguishing System
Source: https://docs.sayed.app/bnbc/part-4-fire-protection/chapter-5-requirements-for-fire-detection-and-extinguishing-system
## **5.1 Scope**
Installation of fire detection and firefighting equipment fixed centrally or localized or portable and their arrangement in the buildings shall be performance based. Construction type and occupancy classification of Buildings shall be as per provisions of this Code. Part 3 of this Code shall be determinant of construction type and the A-Z list for occupancy classification. Installation of fire detection and firefighting equipment shall comply with the Chapter 4 of Part 4 of this Code.
Intent of this Chapter is to reduce the probability of fire incident by confinement, extinguishment to reduce probability of injury or death from fire, structural failure due to fire and safety of building use.
Provisions of this Chapter shall be considered as minimum requirement and shall not be intended to prevent additional installation of higher standard of equipment.
### 5.1.1
Performance based fire protection system which includes “Passive” that is arrangement of building components and “Active” means detection, alarm, extinguishment devices and equipment which shall be incorporated in all buildings unless otherwise specified in this Code. Performance based design considerations shall be as follows:
* (a) The starting of a fire incident shall be a single source to evaluate the fire protection system.
* (b) The prime objective of a fire protection system to safe life and minimization of property damage shall be achieved by using required design scenarios and the performance criteria to be fulfilled. Each design scenario shall be challenging as realistic and the probability of occurrence is present in the building shall be reduced and protected.
* (c) Design scenario shall include but not limited to those specified in Sections 5.1.2 to 5.1.4 and shall be documented and demonstrated to the satisfaction of the authorities having jurisdiction.
* (d) Each design scenario used in the performance-based design shall be translated into input data specification as appropriate for calculation method or model.
* (e) Input data of any design scenario did not analyzed and explicitly addressed or incorporated shall be omitted from input data specifications, shall be identified by a sensitivity analysis of the consequences of the modification for such omissions shall be performed.
### **5.1.2 Design Scenario I**
Fire Class and Fire resistance rating shall be determined as per provision of this Code for the followings:
* (a) All surface finish materials.
* (b) Structural Members.
* (c) Joints of Structural Members.
* (d) All slabs.
* (e) Roof Slab.
* (f) Joints between Slabs.
* (g) All Exterior Walls.
* (h) All Interior Walls.
* (i) Partitions.
* (j) Suspended Ceiling.
Construction classification and the structural stability shall be concluded and documented.
### **5.1.3 Design Scenario II**
Occupancy specific design scenario representative of a typical fire shall explicitly specify the following:
* (a) Occupant activities.
* (b) Number and location of occupants.
* (c) Room size.
* (d) Number of Control Area.
* (e) Furnishings and contents.
* (f) Fuel Properties represented by Fire Class and ignition sources.
* (g) Ventilation conditions.
* (h) First item ignited and its location.
### **5.1.4 Design Scenario III**
* (a) The largest possible fuel load characteristic of the normal operation of the building shall be considered regarding a rapid developing fire in presence of occupants.
* (b) A slow-developing fire shielded from protection in the close proximity to a high occupancy area shall be considered a concern regarding a relatively small ignition source causing a significant fire.
* (c) A concealed space or suspended ceiling space adjacent to a large occupied room shall be considered a concern regarding a fire originating in a concealed space that does not have either detection system or suppression system and then spreading into the room within holding the greatest number of occupants.
* (d) An Ultrafast developing fire in the main exit access portion in a condition when interior doors are open but reduction in number of available of means of egress shall be considered.
* (e) A room normally unoccupied from where a fire starts that can potentially endanger a large number of occupants in a room or other area shall be considered.
* (f) The concern regarding exposure of fire outside of an area of incident started at a remote location either spreading from the area or bypassing barriers spread into another area and developed untenable condition thereof.
* (g) The reliability and the design performance shall be considered for fire detection and protection system in such a way that a fire originating in ordinary combustibles in a room with each passive or active fire protection system or fire protection feature independently rendered ineffective shall be considered individually being unreliable or becoming unavailable. This scenario shall not be considered for a room or a space or a building where fire detection and protection systems or any independent features are absent.
### 5.1.5
Fire class shall be determined for all movables in each room and all control areas in the building.
### **5.1.6 Fire Protection Plan**
A building or part thereof must have a fire protection plan for the following cases.
* (a) High rise building or building sections 33 m and above in heights.
* (b) Building or building sections classified in the occupancy groups G, H, J, K and M which are two or more storey in height with over 1858 m2 per gross floor area or are two or more in height with total area exceeding 4717 m2 gross floor area.
* (c) Building classified as A3 containing 30 or more dwelling units; A4 and A5 having gross floor area of the building more than 1200 m2 .
* (d) Part of a building used as mercantile, assembly, institutional or health care having gross floor area of the building over 930 m2 .
* (e) Alteration to a building or a portion thereof listed in Sections 5.1.6(a) to 5.1.6(d) above, if cost of alteration equivalent to one third cost of new construction of the same or more or involves changes in occupancy classification.
* (f) The plan shall include information where applicable building address, height in meter, occupancy classification, detail occupant load.
* (g) Key Plan shows all floors, exits, corridors, partitions serving as fire separations or compartments, locations and ratings of required enclosures, windowless stair with pressurization, exit discharge, locations of frontage space including street width of abutting plot.
* (h) Descriptions in narrative forms of safety systems and features where applicable, including:
* Communications systems
* Alarm system
* Detection systems
* Location of fire commend station
* Elevator recall
* Emergency lighting and power
* Extinguishing equipment
* Compartmentation
* Horizontal exits
* Mechanical ventilation and air conditioning
* Smoke control systems and equipment
* Furnishing type and materials
* Places of assembly
* Fire department access
* Other system, required or voluntary to be installed
* (i) A fire protection plan shall be signed by the same architect who is signing on the proposed drawings for building approval and any person responsible for the Fire protection design.
## **5.2 Specific Recommendations**
Specific recommendations applicable for buildings complied with the followings:
### 5.2.1
All building constructed monolithically as per provisions of this Code as an inherent full fire resistive construction type shall be termed as Type I-A.
### 5.2.2
All surface finishes shall be Class-I within the range of zero to twenty five flame spread index.
### 5.2.3
Any offsite construction, pre-stressed, pre-fabricated or steel structure encased with fire resistive assembly shall be termed as Modified Type I-A.
### 5.2.4
The following recommendations for fire protection system specified in Sections 5.3 to 5.14 are made based on construction type and surface finishes specified in Sections 5.2.1 and 5.2.2 respectively.
### 5.2.5
All buildings of any occupancy type and construction type as per provisions of this Code other than Sec 5.2.1 with all surface finish as per Sec 5.2.2 shall provide a performance based fire protection.
## **5.3 Occupancy A: Residential**
The residential buildings complied with Sections 5.2.1 and 5.2.2 shall provide the following active fire protection:
### **5.3.1 Occupancy A1 and A2: Single Family Dwelling and Two Families Dwelling**
* (a) For buildings having total floor area less than 500 m2 , fire detection and fixed firefighting arrangements is not required.
* (b) Buildings exceeding total floor area 500 m2 shall have manual alarm system and portable extinguishers provided in the escape stairs route or in lift lobby and as per provision of this Code.
### **5.3.2 Occupancy A3: Flats and Apartments**
* (a) Up to 33 m height fire detection and fixed firefighting arrangement shall not be required.
* (b) No protection is required within the dwelling units of high rise flats and apartments; manual alarm system and fixed hydrant system shall be provided in the landings of fire stairs or in the lift lobby as per the provisions of this Code.
### **5.3.3 Occupancy A4: Mess, Boarding House and Hostels**
* (a) For buildings up to 2 storey height, fire detection, fire alarm and fixed firefighting arrangements shall not be required.
* (b) Buildings having 3 stories and having floor area less than 300 m2 shall not require fire detection and fixed firefighting arrangements.
* (c) The floor area of 3 stories building having more than 300 m2 per floor and less than 33 m height having central corridor with rooms on both sides, manual fire alarm system shall be provided along with portable fire extinguishers. Instead of double loaded corridor a single loaded corridor having 3 m width shall not require any detection and fixed firefighting arrangements.
* (d) High rise boarding house, mess and hostels manually operated electric fire alarm system shall be provided along with hydrant system.
### **5.3.4 Occupancy A5: Hotels and Lodging Houses**
* (a) For buildings up to 2 storey height, fire detection, fire alarm and fixed firefighting arrangements is not required.
* (b) Buildings having 3 floors or above and having floor area less than 300 m2 shall not require fire detection and fixed firefighting arrangements.
* (c) The floor area of such building is more than 300 m2 per floor and low rise building having central corridor with rooms on both sides, manually operated fire alarm system shall be provided along with portable fire extinguishers. For low rise buildings with other configurations performance based firefighting system shall be required as per the provisions of this Code.
* (d) High rise hotels and lodging houses manually operated electric fire alarm system shall be provided along with hydrant system.
## **5.4 Occupancy B: Educational**
The educational buildings complied with Sections 5.2.1 and 5.2.2 shall be provided with the following active fire protection:
### 5.4.1
Low rise buildings with open corridor of 3m width fire detection and fixed firefighting arrangements shall not be required.
### 5.4.2
High rise building or building having central corridor with classrooms on both sides, manual fire alarm and hydrant systems shall be required as per provisions of this Code. Single loaded open corridor having width of 3 m or more shall have detection and manual alarm systems.
### 5.4.3
Where hydrants cannot be used to extinguish fire in those areas appropriate portable firefighting appliances shall be installed as per standard.
## **5.5 Occupancy C: Institution For Care**
The Institution for care buildings complied with Sections 5.2.1 and 5.2.2 shall be provided with the following active fire protection:
### **5.5.1 Occupancy C1: Institution for Care of Children:**
Fire detection and fixed firefighting arrangements shall not be required. Portable firefighting appliances shall be installed as per the provisions of this Code.
### **5.5.2 Occupancy C2: Custodial Institution for the Physically Capable adults:**
Fire detection and fixed firefighting arrangements shall not be required. Portable firefighting appliances shall be installed as per the provisions of this Code.
### 5.5.3 Occupancy C3, C4, C5: Custodial Institution for the Physically Incapable, Penal and mental institutions for children and Penal and mental institutions for adults:
Manually operated electric fire alarm system shall be installed. Portable firefighting appliances shall be installed as per the provisions of this Code.
## **5.6 Occupancy D: Health Care Facilities**
The Health care facilities buildings complied with Sections 5.2.1 and 5.2.2 shall be provided with the following active fire protection:
### 5.6.1 Occupancy D1: Normal and Emergency Medical Facilities:
* (a) Manually operated electric fire alarm system or automatic fire alarm system shall be installed in the duty room, so that the duty personnel receive the fire warning well in advance. Portable fire fighting appliances shall be installed as per the provisions of this Code.
* (b) For low rise health care facility buildings with more the 300 m2 per floor, performance based fire fighting system shall be required as per the provisions of this Code.
* (c) For high rise health care facility buildings, manually operated electric fire alarm system shall be provided along with hydrant system.
## **5.7 Occupancy E: Business**
The Business buildings complied with Sections 5.2.1 and 5.2.2 shall be provided with the following active fire protection:
| **No.** | **Buildings** | **Active Fire Protection** |
| ------- | ----------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| (i) | Office buildings up to 2 storey
high and 500 m2single effective
undivided space in a floor. | Portable fire extinguishers or hydrants. |
| (ii) | Office buildings more than 2
storey high or more than 500 m2
single effective undivided space
in a floor. | Manually operated electric fire alarm
system shall be provided along with
portable fire extinguishers or hydrants. |
| (iii) | Laboratories with precession
instruments. | Automatic
fire
alarm
system
and
performance based extinguishing system. |
| (iv) | Control areas of office buildings
dealing with flammable liquids. | Automatic foam or gaseous or dry chemical
fire extinguishing system required along
with portable fire extinguishers. |
| (v) | Solvent storage in a control area
of an office | Automatic
fire
alarm
system
and
performance based foam or gaseous or dry
chemical fire extinguishers or portable fire
extinguishers. |
| (vii) | Telecommunication, Internet
gateway equipment or
computer installation in an
unattended server room. | Automatic
fire
alarm
system
and
performance based fixed gaseous or fixed
vaporizing liquid extinguishers or portable
fire extinguishers. |
| (viii) | Electrical low tension
distribution panel room in a sub-
station. | Automatic
fire
alarm
system
and
performance based localized fixed gaseous
or
vaporizing
liquid
extinguisher
or
portable fire extinguishers. |
| (ix) | Space under one false ceiling
more than 500 m2 | Automatic fire alarm system shall be
installed for above and under the false
ceiling. |
| (x) | Essential Services (Occupancy E3) | Due to importance of services and functionality of the building of this occupancy classification during any national or local emergency situation thus the fire protection system design shall be performance based (Sec 5.1.1). |
| (xi) | High rise office buildings | Manually operated electric fire alarm system shall be provided along with hydrant system. |
## **5.8 Occupancy F: Mercantile**
The Mercantile buildings complied with Sections 5.2.1 and 5.2.2 shall be provided with the following active fire protections:
### **5.8.1 Occupancy F1: Small Shops and Markets**
| **No.** | **Mercantile** | **Active Fire Protection** |
| ------- | ---------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------- |
| (i) | Whole sale establishments,
transport booking
establishments. | Manual fire alarm system shall be provided
along with portable fire extinguishers or
hydrant. |
| (ii) | Other premises (other than
shops, stores, markets etc.) | Manual fire alarm system shall be provided
along with portable fire extinguishers or
hydrant. |
### **5.8.2 Occupancy F2: Large Shops and Markets**
| **No.** | **Mercantile** | **Active Fire Protection** |
| ------- | ------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------- |
| (i) | Shopping arcade with central
corridors open to sky | Manual fire alarm system and portable fire
extinguishers shall be provided or hydrant. |
| (ii) | Mercantile building under
covered roof with single effective
undivided space more than 500
m2on each floor | Manual fire alarm system and hydrant
system with performance based portable
fire extinguisher shall be installed. |
| (iii) | Underground mercantile
structure | Automatic fire alarm system, sprinklers and
standpipe with performance based portable
fire extinguisher shall be installed. |
### **5.8.3 Occupancy F3: Petrol and CNG Stations**
| **No.** | **Mercantile** | **Active Fire Protection** |
| ------- | ---------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------- |
| (i) | Petrol pump and CNG station,
automobile garages | Fixed automatic foam or gaseous or dry
chemical fire extinguishing system shall be
provided along with portable extinguisher. |
| (ii) | Aircraft hangars | Automatic foam or gaseous or dry chemical
fire extinguishing system shall be provided
along with portable extinguisher. |
## **5.9 Occupancy G: Industrial**
The Industrial buildings complied with Sections 5.2.1 and 5.2.2 shall be provided with the following active fire protection:
### **5.9.1 Occupancy G1: Low Hazard Industries**
Manually operated electric fire alarm system shall be installed with portable fire extinguishers or hydrants when occupant loads are not more than 150.
Where occupant loads are more than 150 active fire protections shall be performance based.
### **5.9.2 Occupancy G2: Moderate Hazard Industries**
Among the moderate hazard industries where large number of occupants are densely populated in a building, the active fire protections shall be performance based. Fire safety requirement for such type industry is elaborated as follows:
* (a) Where occupancy load is more than 150 per production area shall have minimum 9.5 m3 air volume per occupant.
* (b) There shall have direct exits from the ground floor. This exit doors shall be used by only the occupant of the ground floor.
* (c) Buildings less than 33 m in height shall have open stair and the interior stairs shall be protected by fire rated enclosures. Occupants located 33 m or above, all stair shall have smoke proof enclosures constructed as per provision of the Code.
* (d) All windows or openings on exterior walls passable by occupant located above 3 m in height shall be protected by grills and all these grills shall be designed as such that a part or a portion having minimum 0.6 m height and minimum 0.75 m width framed and the grill within the frame shall be side hinged or pivoted so that it can swing. This swing type operable portion must be always locked and in case of emergency the firefighters can open by breaking the lock for rescue operation.
* (e) The floor shall be constructed such that the travel path of the occupant shall not be exceeded as per Table 4.3.7 of this Code.
* (f) As per general requirements, all exit access doors shall be of a side-swinging type. Fulfilling the conditions laid down by NFPA 101, edition 2015, article 7.2.1.4 horizontal sliding or vertical-rolling security grills or door assemblies that are part of the required means of egress shall be permitted.
* (g) All raw materials, finished good and accessories shall be stored in control areas as per provision of part 3.
* (h) Density of storage materials per control area shall not be exceeded the provision of this Code.
* (i) During production that is feeding, checking for quality control rejects, waiting area for finishing, packing, cartooning etc. in every case dedicated area shall be defined as on process storages. The total volume of materials on process shall be such that in every four hour the material shall be used up and the finished goods shall be transferred to controlled area as finished goods store.
* (j) From each end every work station shall be connected with a passage. The width of the passage shall comply with the provision of this Code Chapter 3 Part 4.
* (k) Cargo lift and passenger lift shall have smoke proof lift lobby.
* (l) Occupant load in a single effective undivided space shall not exceed 600. In case of existing building if the occupant load of a single effective undivided space exceeds 600, the space shall be compartmented complying with the horizontal exit provision of the Code.
* (m) Where control areas and in process stores having materials may cause a fire classified as fire class A shall have hydrant system as per provision of this Code. In the utility occupancy areas fire extinguishing system shall be installed as per provision as specified for utilities of this Code.
* (n) If there any change of fire classification due to the working condition or raw materials than appropriate extinguishing system shall be installed as per provision of this Code.
* (o) Up to 750 m2 single effective undivided space in a floor shall be installed with manual fire alarm system with portable fire extinguishers or as an alternate hydrants system shall be installed as per provisions of this Code.
* (p) Above 750 m2 single effective undivided space in a floor shall be fitted with manual fire alarms system with hydrants shall be installed.
## **5.10 Occupancy H: Storage**
The Storage buildings complied with Sections 5.2.1 and 5.2.2 shall be provided with the following Active fire protection:
### **5.10.1 Occupancy H1: Low Fire Risk Storage**
Manually operated electric fire alarm system shall be installed. Depending on the type of materials to be stored, performance based fire protection shall be installed as per provision of this Code.
### **5.10.2 Occupancy H2: Moderate Fire Risk Storage**
Performance based fire protection system shall be installed as per provision of this Code.
## **5.11 Occupancy I: Assembly**
The Assembly buildings complied with Sections 5.2.1 and 5.2.2 shall be provided with the following Active fire protection:
### **5.11.1 Occupancy I1: Large Assembly with Fixed Seats**
All auditorium, corridor, green rooms and canteen attached to assembly buildings shall be fitted with manual fire alarm system and the performing stage should preferably be covered by an automatic sprinkler system. Portable firefighting appliances shall be installed as per specification of the manufacturer and provision of this Code.
### **5.11.2 Occupancy I2: Small Assembly with Fixed Seats**
Requirements specified in Sec 5.6.1 shall be complied.
### **5.11.3 Occupancy I3: Large Assembly without Fixed Seats**
Automatic fire alarm system shall be provided. Portable firefighting appliances shall be installed as per specification of the manufacturer and provision of this Code.
### **5.11.4 Occupancy I4: Small Assembly without Fixed Seats**
Requirements specified in Sec 5.6.3 shall be complied.
### **5.11.5 Occupancy I5: Sports Facilities**
Manually operated electric fire alarm system shall be provided. Portable firefighting appliances shall be installed as per specification of the manufacturer and provision of this Code.
## **5.12 Occupancy J: Hazardous**
The Hazardous buildings complied with Sections 5.2.1 and 5.2.2 shall be provided with the following Active fire protection:
All hazardous occupancies shall be installed with automatic fire alarm and automatic fixed firefighting gaseous or foam or dry chemical extinguishing system as compatible with class of fire shall be installed as per provision of this Code.
## **5.13 Occupancy K: Garages**
The parking buildings (garages) complied with Sections 5.2.1 and 5.2.2 shall provide the following fire protections:
* (a) Where both parking and repair operations are conducted in the same building, the entire building shall comply with the requirement stated in this Code for Occupancy G1.
* (b) Where the parking and repair sections are separated by not less than 1-hour fire-rated construction, the parking and repair sections shall be permitted to be treated separately.
* (c) In areas where repair operations are conducted, the requirement of Occupancy G1 shall be fulfilled.
* (d) The area used only for parking shall fulfill the requirement as laid down in chapter 42 of NFPA 101 edition 2015.
## **5.14 Occupancy L: Utilities**
Fire protection system shall be as stated in Sec 2.12 of this Code.
## **5.15 Occupancy M: Miscellaneous**
Performance based fire protection system shall be installed.
# Part IV: Fire Protection
Source: https://docs.sayed.app/bnbc/part-4-fire-protection/index
Means of egress, equipment standards, and fire detection and extinguishing systems.
Part IV covers precautionary requirements, means of egress, in-built facility standards, and fire detection and extinguishing systems by occupancy type.
General provisions for fire protection.
Precautionary fire safety requirements.
Requirements for exits and means of egress.
Standards for fire protection equipment and in-built facilities.
Fire detection and extinguishing system requirements by occupancy.
# Chapter 1: Scope and Definitions
Source: https://docs.sayed.app/bnbc/part-5-building-materials/chapter-1-scope-and-definitions
## **1.1 Scope**
This Part specifies the minimum requirements of materials to be complied with in buildings and works under the provisions of the Code.
For each of the building materials the applicable standard specifications and test methods are listed. All materials shall conform to these Standards.
The list of standards given in this Part of the Code would be augmented from time to time by amendments, revisions and additions of which the Authority shall take cognizance. The latest version of a specification shall, as far as practicable, be applied in order to fulfil the requirements of this Part.
In view of the limited number of Bangladesh Standards (BDS) for building materials available at the present time, a number of standards of other countries have been referenced in this Code as applicable standards. As more standards of BDS regarding building materials become available and adopted by amendment of this Code, they shall supplement and/or replace the relevant standards listed in this Part.
## **1.2 Terminology**
This Section provides an alphabetical list of the terms used in and applicable to this Part of the Code. In case of any conflict or contradiction between a definition given in this Section and that in Part 1, the meaning provided in this Part shall govern for interpretation of the provisions of this Part.
**ACTUAL DIMENSIONS**: Measured dimensions of a designated item.
**ADMIXTURE**: Material other than water, aggregate, or hydraulic cement used as an ingredient of concrete and added to concrete before or during its mixing to modify its properties.
**AGGREGATE**: Granular material, such as sand, gravel, crushed stone, crushed brick and iron blast-furnace slag, when used with a cementing medium that forms hydraulic cement concrete or mortar.
**AGGREGATE, LIGHT WEIGHT**: Aggregate with a dry, loose weight of 11.25 $\text{kN/m}^3$ or less.
| Item | Description |
| ------------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| CONCRETE | A mixture of Portlandcement or any other hydraulic cement,
fine aggregate, coarse aggregate and water, with or without
admixtures. |
| CONCRETE, PLAIN | Concrete that does not conform to the definition of reinforced
concrete. |
| CONCRETE,
PRECAST | Plain or reinforced concrete element cast separately before they
are fixed in position. |
| CONCRETE,
PRESTRESSED | Reinforced concrete in which internal stresses have been
introduced to reduce potential tensile stresses in concrete
resulting from loads. |
| CONCRETE,
REINFORCED | Concrete containing adequate reinforcement, prestressed or
non-prestressed, and designed on the assumption that the two
materials act together in resisting forces. |
| FIBRE BOARD | A fibre-felted, homogenous panel made from lignocellulosic
fibres (usually wood or cane) and having a unit weight between
1.6 $\text{kN/m}^3$and 5 $\text{kN/m}^3$. |
| HARD BOARD | A fibre-felted homogenous panel made of lignocellulosic fibres
consolidated under heat and pressure in a hot press to a density
of 4.9 $\text{kN/m}^3$or above. |
| MASONRY UNIT | Brick, tile, stone, glass-block or concrete-block used in
masonry constructions. |
| MASONRY UNIT,
GROUTED
HOLLOW | Form of grouted masonry construction in which certain
designated cells of hollow units are continuously filled with
grout. |
| MASONRY UNIT,
HOLLOW | A masonry unit whose net cross-sectional area in every plane
parallel to the bearing surface is less than 75 percent of the
gross cross-sectional area in the same plane. |
| MASONRY UNIT,
SOLID | A masonry unit whose net cross-sectional area in every plane
parallel to the bearing surface is 75 percent or more of the gross
cross-sectional area in the same plane. |
| NOMINAL
DIMENSIONS | Nominal dimensions of masonry units are equal to their
specified dimensions plus the thickness of the joint with which
the unit is laid. |
| PARTICLE BOARD | Amanufactured panel product consisting of particles of wood
or combinations of wood particles and wood fibres cemented
together with synthetic resins or other suitable bonding system
by an appropriate bonding process. |
| PLYWOOD | A built-up panel of laminated veneers. |
| REINFORCED
MASONRY | Form of masonry construction in which reinforcement acting in
conjunction with the masonry is used to resist designed forces. |
| REINFORCEMENT | Reinforcing bars, plain or deformed, excluding prestressing
tendons, bar and rod mats, welded smooth wire fabric and
welded deformed wire fabric used in concrete. |
| REINFORCEMENT,
DEFORMED | Deformed reinforcing bars, bar and rod mats, deformed wire,
welded smooth wire fabric and welded deformed wire fabric. |
| REINFORCEMENT,
PLAIN | Reinforcement that does not conform to definition of deformed
reinforcement. |
| REINFORCEMENT,
SPIRAL | Continuously wound reinforcement in the form of a cylindrical
helix. |
| STIRRUP | Reinforcement used to resist shear and torsion stresses in
structural member; typically bars, wires, or welded wire fabric
(smooth or deformed) bent into L, U or rectangular shapes and
located perpendicular to or at an angle to longitudinal
reinforcement. (The term "Stirrup" is usually applied to lateral
reinforcement in flexural members and the term "ties" to those
in compression members). |
| STRUCTURAL
GLUED
LAMINATED
TIMBER | Any member comprising an assembly of laminations of lumber
in which the grain of all laminations is approximately parallel
longitudinally in which the laminations are bonded with
adhesives. |
| TENDON | Steel element such as wire, cable, bar, rod or strand, or a bundle
of such elements, used to impart prestress to concrete. |
| TIE | A loop of reinforcing bar or wire enclosing longitudinal
reinforcement. |
| YIELD STRENGTH | The stress at which plastic deformation takes place under
constant or reduced load. |
# Chapter 2: Building Materials
Source: https://docs.sayed.app/bnbc/part-5-building-materials/chapter-2-building-materials
## **2.1 General**
Materials used for the construction of buildings shall conform to standard specifications listed in this Part of the Code. Any deviation from the type design or architectural detail from those specified in these standards may be accepted by the Building Official as long as the materials standards specified therein are conformed with.
### **2.1.1 New or Alternative Materials**
The provisions of this Part are not intended to prevent the use of any new and alternative materials. Any such material may be approved provided it is shown to be satisfactory for the purpose intended and at least equivalent of that required in this Part in quality, strength, effectiveness, fire resistivity, durability, safety, maintenance and compatibility.
Approval in writing shall be obtained by the owner or his agent before any new, alternative or equivalent materials are used. The Building Official shall base such approval on the principle set forth above and shall require that specified tests be made as per Sec 2.1.4 or sufficient evidence or proof be submitted, at the expense of the owner or his agent, to substantiate any claim for the proposed material.
### **2.1.2 Used Materials**
The provisions of this Part do not preclude the use of used or reclaimed materials provided such materials meet the applicable requirements as for new materials for their intended use.
### **2.1.3 Storage of Materials**
All building materials shall be stored at the building site(s) in such a way as to prevent deterioration or the loss or impairment of their structural and other essential properties (Part 7 of this Code).
### **2.1.4 Methods of Test**
Every test of material required in this Part, or by the Building Official, for the control of quality and for the fulfillment of design and specification requirements, shall be carried out in accordance with a standard method of test issued by the Bangladesh Standards and Testing Institution (BSTI). In the absence of Bangladesh Standards, the Building Official shall determine the test procedures. Laboratory tests shall be conducted by recognized laboratories acceptable to the Building Official.
If, in the opinion of the Building Official, there is insufficient evidence of compliance with any of the provisions of the Code or there is evidence that any material or construction does not conform to the requirements of this Code, the Building Official may require tests to be performed as proof of compliance. The cost of any such test shall be borne by the owner.
The manufacturer or supplier shall satisfy himself that the materials conform to the relevant standards and if requested shall furnish a certificate or guarantee to this effect.
## **2.2 Masonry**
### **2.2.1 Aggregates**
Aggregates for masonry shall conform to the standards listed as follows: ASTM C144 Aggregates for Masonry Mortar; ASTM C404 Aggregates for Masonry Grout; ASTM C331 Lightweight Aggregates for Concrete Masonry Units (the applicable Standards for masonry are listed at the end of this Section).
### **2.2.2 Cement**
Cement for masonry shall conform to the standards listed as follows: BDS EN 197-1: 2003 Cement Part-1 Composition, specifications and conformity criteria for common cements; or ASTM C150/C150M Portland Cement; ASTM C91 Masonry Cement; ASTM C595/C595M Blended Hydraulic Cements.
### **2.2.3 Lime**
Limes for masonry shall conform to the standards listed as follows: ASTM C5, Quicklime for Structural Purposes; ASTM C207, Hydrated Lime for Masonry Purposes.
### **2.2.4 Masonry Units**
* (a) Clay: Masonry units of clay (or shale) shall conform to the standards listed as follows: BDS 208: 2009, Common building clay bricks; BDS 1249:1989, Acid resistant bricks; BDS 1250: 1990, Burnt clay facing bricks; BDS 1263: 1990, Burnt clay hollow bricks for walls and partitions; BDS 1264 : 1990, Glossary of terms relating to structural clay products; BDS 1432: 1993, Burnt clay perforated building bricks; BDS 1803: 2008, Specification for hollow clay bricks and blocks; ASTM C34 Structural Clay Load-Bearing Wall Tile; ASTM C212 Structural Clay Facing Tile; ASTM C56 Structural Clay Non-Load-Bearing Tile; and IS 7556 Burnt clay jallies.
* (b) Concrete: Concrete masonry units shall conform to the standards listed as follows :
| Standard | Description |
| ------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS EN 771-3 | Specification for masonry units-Part: 3 Aggregate concrete
masonry units (dense and lightweight aggregates). |
| BDS EN 772-1 | Methods of test for masonry units-Part 1: Determination of
compressive strength. |
| BDS EN 772-2 | Methods of test for masonry units-Part 2: Determination of
percentage area of voids in masonry units (by paper
indentation). |
| BDS EN 772-6 | Methods of test for masonry units-Part 6: Determination of
bending tensile strength of aggregate concrete masonry units. |
| BDS EN 772-11 | Methods of test for masonry units-Part 11: Determination of
water absorption of aggregate concrete, autoclaved aerated
concrete, manufactured stone and natural stone masonry units
due to capillary action and the initial rate of water absorption
of clay masonry units. |
| BDS EN 772-13 | Methods of test for masonry units-Part 13: Determination of
net and gross dry density of masonry units (except for natural
stone). |
| BDS EN 772-14 | Methods of test for masonry units-Part 14: Determination of
moisture movement of aggregate concrete and manufactured
stone masonry units. |
| BDS EN 772-16 | Methods of test for masonry units-Part 16: Determination of
dimensions. |
| BDS EN 772-20 | Methods of test for masonry units-Part 20: Determination of
flatness of faces of masonry units. |
| BDS EN 1052-3 | Methods of test for masonry-Part 3: Determination of initial
shear strength BDS EN 1745: 2009 Masonry and masonry
products-Methods for determining design thermal values. |
| ASTM C55 | Concrete Building Bricks. |
| ASTM C90 | Specification for Load-Bearing Concrete Masonry Units. |
| ASTM C129 | Non-Load Bearing Units. |
* (c) Others
| Item | Description |
| -------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Material | Description |
| Calcium Silicate | Calcium Silicate Face Brick (Sand-Lime Brick) shall
conform to ASTM C73 Standard Specification. |
| Glazed Masonry Units | Glazed Masonry building units shall conform to the
standards listed as follows: ASTM C126, Ceramic-Glazed
Structural Clay Facing Tile, Facing Brick, and Solid
Masonry Units; or ASTM C744 Prefaced Concrete and
Calcium Silicate Masonry Units. |
| Glass Block | Glass block may be solid or hollow and contain inserts; all
mortar contact surfaces shall be treated to ensure adhesion
between mortar and glass. |
| Un-burnt Clay
Masonry Units | Masonry of un-burnt clay units including cement stabilized
and lime stabilized blocks shall not be used, in any building
more than one storey in height. |
| Architectural Terra
Cotta | All architectural terra cotta units shall be formed with a
strong homogeneous body of hard-burnt weather-resistant
clay which gives off a sharp metallic ring when struck. All
units shall be formed to engage securely with and anchor to
the structural frame or masonry wall. |
| Natural Stone | Natural stone for masonry shall be sound and free from loose
friable inclusions. Natural stone shall have the strength and
fire resistance required for the intended use. |
| Cast Stone | All cast stone shall be fabricated of concrete or other
approved materials of required strength, durability and fire
resistance for the intended use and shall be reinforced where
necessary. |
| AAC Masonry | AAC (Autoclaved Aerated Concrete) masonry units shall
conform to ASTM C1386 for the strength class specified. |
| Ceramic tile | Ceramic tile shall be as defined in, and shall conform to the
requirements of ANSI A137.1. |
| Second Hand Units | Second hand masonry units shall not be used unless the units
conform to the requirements for new units. The units shall be
of whole, sound material and be free from cracks and other
defects that would interfere with proper laying or use. All old
mortar shall be cleaned from the units before reuse. |
### **2.2.5 Mortar**
Mortar shall consist of a mixture of cementitious material and aggregates to which sufficient water and approved additives, if any, have been added to achieve a workable, plastic consistency. Cementitious materials for mortar shall be one or more of the following: lime, masonry cement, Portland cement and mortar cement. Mortar for masonry construction other than the installation of ceramic tile shall conform to the requirements of BDS 1303: 1990 Chemical resistant mortars; BDS 1304:1990 Methods of test for chemical resistant mortars; ASTM C270, Mortar for Unit Masonry.
### **2.2.6 Grout**
Grout shall consist of a mixture of cementitious materials and aggregates to which water has been added such that the mixture will flow without segregation of the constituents. Cementitious materials for grout shall be one or both of the following: Lime and Portland cement. Grout shall have a minimum compressive strength of 13 MPa. Grout used in reinforced and unreinforced masonry construction shall conform to the requirements of ASTM C476 Grout for Masonry.
### **2.2.7 Mortar for Ceramic Wall and Floor Tile**
Portland cement mortars for installing ceramic wall and floor tile shall comply with ANSI A 108.1-2005 listed in Sec 2.2.11 and be of the composition specified in Table 5.2.1.
#### 2.2.7.1 Dry-set leveling cement mortars
Premixed prepared leveling cement mortars, which require only the addition of water and are used in the installation of ceramic tile, shall comply with ANSI A118.1. The shear bond strength for tile set in such mortar shall be as required in accordance with ANSI A118.1. Tile set in dry-set Portland cement mortar shall be installed in accordance with ANSI A108.5.
#### 2.2.7.2 Latex-modified leveling cement mortar
Latex-modified leveling cement thin-set mortars in which latex is added to dry-set mortar as a replacement for all or Part of the gauging water that are used for the installation of ceramic tile shall comply with ANSI A118.4. Tile set in latex-modified leveling cement shall be installed in accordance with ANSI A108.5.
#### 2.2.7.3 Epoxy mortar
Ceramic tile set and grouted with chemical-resistant epoxy shall comply with ANSI A118.3. Tile set and grouted with epoxy shall be installed in accordance with ANSI A108.6.
#### 2.2.7.4 Furan mortar and grout
Chemical-resistant furan mortar and grout that are used to install ceramic tile shall comply with ANSI A118.5. Tile set and grouted with furan shall be installed in accordance with ANSI A108.8.
#### 2.2.7.5 Modified epoxy-emulsion mortar and grout
Modified epoxy-emulsion mortar and grout that are used to install ceramic tile shall comply with ANSI A118.8. Tile set and grouted with modified epoxy-emulsion mortar and grout shall be installed in accordance with ANSI A108.9.
#### 2.2.7.6 Organic adhesives
Water-resistant organic adhesives used for the installation of ceramic tile shall comply with ANSI A136.1. The shear bond strength after water immersion shall not be less than 275 kPa (40 psi) for Type I adhesive and not less than 138 kPa (20 psi) for Type II adhesive when tested in accordance with ANSI A136.1. Tile set in organic adhesives shall be installed in accordance with ANSI A108.4.
#### 2.2.7.7 Portland cement grouts
Portland cement grouts used for the installation of ceramic tile shall comply with ANSI A118.6. Portland cement grouts for tile work shall be installed in accordance with ANSI A108.10.
#### 2.2.7.8 Mortar for Autoclaved Aerated Concrete (AAC) masonry
Thin-bed mortar for AAC masonry shall comply with Article 2.1 C.1 of TMS 602/ACI 530.1/ASCE 6. Mortar used for the leveling courses of AAC masonry shall comply with Article 2.1 C.2 of TMS 602/ACI 530.1/ASCE 6.
### **2.2.8 Metal Ties and Anchors**
Metal ties and anchors shall conform to the standards listed as follows: ASTM A82/A82M, Wire Anchor and Ties; and ASTM A1008/A1008M, Sheet Metal Anchors and Ties.
**Table 5.2.1: Ceramic Tile Mortar Compositions**
| Item | Description | Description |
| -------- | ----------------------------- | ----------------------------------------------------------------------------------------------- |
| Walls | Scratch coat | 1 cement, 0.20 hydrated lime\*,
4 dry or 5 damp sand |
| | Setting bed and leveling coat | 1 cement, 0.50 hydrated lime,
5 damp sand to 1 cement,
1 hydrated lime; 7 damp sand |
| Floors | Setting bed | 1 cement; 0.10 hydrated lime;
5 dry or 6 damp sand; or 1
cement; 5 dry or 6 damp sand |
| Ceilings | Scratch coat and sand bed | 1 cement; 0.50 hydrated lime;
2.50 dry sand or 3 damp sand |
* Lime may be excluded from the mortar if trial mixes indicate that the desired workability and performance are achieved without lime.
### **2.2.9 Reinforcement**
Reinforcement in masonry shall conform to the standards listed as follows: ASTM A82/A82M, Cold Drawn Steel Wire for Concrete Reinforcement; ASTM A615/A615M, Deformed and Plain Billet Steel Bars; ASTM A996/A996M, Rail-Steel Deformed and Plain Bars; ASTM A996/A996M, Axle-Steel Deformed and Plain Bars; ASTM A706/A706M, Low-Alloy Steel Deformed Bars; ASTM A767/A767M, Zinc-Coated (Galvanized) Steel Bars; and ASTM A775/A775M, Epoxy-Coated Reinforcing Steel Bars.
### **2.2.10 Water**
Water used in mortar or grout shall be clean and free of deleterious amounts of acid, alkalis or organic material or other harmful substances.
### **2.2.11 Applicable Standards for Masonry**
The applicable standards for Masonry are listed below:
BDS EN 197-1 Cement Part-1 Composition, Specifications and Conformity Criteria for Common Cements.
BDS 208 Specification for Common Building Clay Bricks : Specifies the dimensions, quality and strength of common burnt clay bricks, methods of sampling, testing etc.
| Item | Description |
| ----------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS 238 | Fire Clay Refractory Bricks and Shapes for General Purposes: This
Standard specifies the requirements for fireclay refractory bricks
and shapes meant for general purpose; the products are classified in
four grades according to the duty for which they are suitable. |
| BDS 1249 | Acid Resistant Bricks: It specifies the requirements for acid-
resistant bricks, dimensions, tolerances, test etc. |
| BDS 1250 | Burnt Clay Facing Bricks: It specifies the dimensions, quality and
strength of burnt clay facing bricks used in building and other
structure, physical requirements etc. |
| BDS 1263 | Burnt Clay Hollow Bricks for Walls and Partitions: It covers the
dimensions, quality and strength for hollow bricks made from burnt
clay and having perforations through and at right angle to the
bearing surface tests. |
| BDS 1264 | Glossary of Terms Relating to Structural Clay Products: It covers
the definition of common terms applicable to structural clay
products, used in building and civil engineering works. |
| BDS 1432 | Burnt Clay Perforated Building Bricks: Specifies the requirements
in regard to dimensions, perforations, quality, strength and also for
quality of surface in case of special grade for facing bricks of
perforated burnt clay building bricks for use in walls and partitions. |
| BDS 1433 | Dimensions quantities in general construction work: Specifies the
various dimensional values in SI units used in general construction
work. |
| BDS 1803 | Specification for hollow clay bricks and blocks. |
| BDS EN 1338 | Concrete paving blocks-Requirements and test methods. |
| BDS EN 1339 | Concrete paving flags-Requirements and test methods. |
| BDS EN 1340 | Concrete kerb units-Requirements and test methods. |
| BDS EN 13369 | Common rules for precast concrete products. |
| BDS EN 771-3 | Specification for masonry units Part 3: Aggregate concrete masonry
units (dense and lightweight aggregates). |
| BDS EN 772-1 | Methods of test for masonry units Part 1: Determination of
compressive strength. |
| BDS EN 772-2 | Methods of test for masonry units Part 2: Determination of
percentage area of voids in masonry units (by paper indentation). |
| BDS EN 772-6 | Methods of test for masonry units Part 6: Determination of bending
tensile strength of aggregate concrete masonry units. |
| BDS EN 772-11 | Methods of test for masonry units Part 11: Determination of water
absorption of aggregate concrete, autoclaved aerated concrete,
manufactured stone and natural stone masonry units due to capillary
action and the initial rate of water absorption of clay masonry units. |
| BDS EN 772-13 | Methods of test for masonry units Part 13: Determination of net and
gross dry density of masonry units (except for natural stone). |
| BDS EN 772-14 | Methods of test for masonry units Part 14: Determination of
moisture movement of aggregate concrete and manufactured stone
masonry units. |
| BDS EN 772-16 | Methods of test for masonry units Part 16: Determination of
dimensions. |
| BDS EN 772-20 | Methods of test for masonry units Part 20: Determination of flatness
of faces of masonry units. |
| BDS EN 1052-3 | Methods of test for masonry Part 3: Determination of initial shear
strength. |
| BDS EN 1745 | Masonry and masonry products: Methods for determining design
thermal values. |
| ANSI A108.1A | Installation of Ceramic Tile in the Wet-Set Method, with Portland
Cement Mortar. |
| ANSI A108.1B | Installation of Ceramic Tile, Quarry Tile on a Cured Portland
Cement Mortar Setting Bed with Dry-set or Latex-Portland Mortar. |
| ANSI A108.1 | Specifications for the Installation of Ceramic Tile with Portland
Cement Mortar. |
| ASTM A82/
A82M | Specification for Steel Wire, Plain, for Concrete Reinforcement. |
| ASTM A1008/
A1008M | Standard Specification for Steel, Sheet, Cold-Rolled, Carbon,
Structural, High-Strength Low-Alloy, High-Strength Low-Alloy
with Improved Formability, Solution Hardened, and Bake
Hardenable. |
| ASTM
A615/A615M | Standard Specification for Deformed and Plain Carbon-Steel Bars
for Concrete Reinforcement. |
| ASTM
A996/A996M | Standard Specification for Rail-Steel and Axle-Steel Deformed Bars
for Concrete Reinforcement. |
| ASTM
A706/A706M | Standard Specification for Low-Alloy Steel Deformed and Plain
Bars for Concrete Reinforcement. |
| ASTM A183 | Standard Specification for Carbon Steel Track Bolts and Nuts. |
| ASTM
A775/A775M | Standard Specification for Epoxy-Coated Steel Reinforcing Bars. |
| ASTM C5 | Standard Specification for Quicklime for Structural Purposes. |
| ASTM C34 | Standard Specification for Structural Clay Load-Bearing Wall Tile. |
| ASTM C55 | Standard Specification for Concrete Building Brick. |
| ASTM C56 | Standard Specification for Structural Clay Non load bearing Tile. |
| ASTM C73 | Standard Specification for Calcium Silicate Brick (Sand-Lime
Brick). |
| ASTM C90 | Standard Specification for Load bearing Concrete Masonry Units. |
| ASTM C91 | Standard Specification for Masonry Cement. |
| ASTM C126 | Standard Specification for Ceramic Glazed Structural Clay Facing
Tile, Facing Brick, and Solid Masonry Units. |
| ASTM C129 | Standard Specification for Non-load bearing Concrete Masonry
Units. |
| ASTM C144 | Standard Specification for Aggregate for Masonry Mortar. |
| ASTM C90 | Standard Specification for Load bearing Concrete Masonry Units. |
| ASTM C150/
C150M | Standard Specification for Portland Cement. |
| ASTM C207 | Standard Specification for Hydrated Lime for Masonry Purposes. |
| ASTM C212 | Standard Specification for Structural Clay Facing Tile. |
| ASTM C270 | Standard Specification for Mortar for Unit Masonry. |
| ASTM C331 | Standard Specification for Lightweight Aggregates for Concrete
Masonry Units. |
| ASTM C404 | Standard Specification for Aggregates for Masonry Grout. |
| ASTM C476 | Standard Specification for Grout for Masonry. |
| ASTM
C595/C595M | Standard Specification for Blended Hydraulic Cements. |
| ASTM C744 | Standard Specification for Prefaced Concrete and Calcium Silicate
Masonry Units. |
## **2.3 Cement and Concrete**
### **2.3.1 General**
Materials used to produce concrete, and admixtures used for concrete shall comply with the requirements of this Section and those of Chapter 5 Part 6 of this Code.
### **2.3.2 Aggregates**
Concrete aggregates shall conform to the following standards:
BDS 243: 1963, Coarse and Fine Aggregates from Natural Sources for Concrete; ASTM C33/C33M Concrete Aggregates; ASTM C330/C330M Lightweight Aggregates for Structural Concrete; ASTM C637 Aggregates for Radiation-Shielding Concrete; ASTM C332 Lightweight Aggregate for Insulating Concrete; IS: 9142 Artificial lightweight aggregates for concrete masonry units.
#### 2.3.2.1 Special tests
Aggregates failing to meet the specifications listed in Sec 2.4.2 shall not be used unless it is shown by special test or actual service experience to produce concrete of adequate strength and durability and approved by the Building Official.
#### 2.3.2.2 Nominal size
Nominal maximum size of coarse aggregate shall not be larger than:
* (a) One-fifth of the narrowest dimension between sides of forms; or
* (b) One-third the depth of slabs; or
* (c) Three fourths the minimum clear spacing between individual reinforcing bars or wires, bundles of bars, or pre-stressing tendons or ducts.
**Exception:**
The above limitations regarding size of coarse aggregate may be waived if, in the judgment of the Engineer, workability and methods of consolidation are such that concrete can be placed without honeycomb or voids.
### **2.3.3 Cement**
Cement shall conform to the following standards: BDS EN 197-1:2003 Cement Part-1 Composition, specifications and conformity criteria for common cements, BDS 612 Sulphate resisting Portland cement-type A, ASTM C150/C150M Standard Specification for Portland Cement, BDS 232 Portland cement, ASTM C595/C595M Blended Hydraulic Cements, and to other such cements listed in ACI 318.
### **2.3.4 Water**
Water used in mixing concrete shall be clean and free from injurious amounts of oils, alkalies salts, organic materials or other substances that may be deleterious to concrete or reinforcement. Water shall conform to the following standards: BDS ISO 12439:2011 Mixing water for concrete.
#### 2.3.4.1 Chloride ions
Mixing water for pre-stressed concrete or for concrete that will contain aluminium embedment, including the portion of mixing water contributed in the form of free moisture on aggregates shall not contain deleterious amounts of chloride ion. The maximum water-soluble chloride ion concentration in concrete shall not exceed the limitations specified in Sec 5.5.3 Part 6.
#### 2.3.4.2 Potability
Nonpotable water shall not be used in concrete unless the following are satisfied:
* (a) Selection of concrete proportions shall be based on concrete mixes using water from such source.
* (b) Mortar test cubes made with non-potable mixing water shall have 7 days and 28 days strengths equal to at least 90 percent of strengths of similar specimens made with potable water.
### **2.3.5 Admixtures**
Admixtures to be used in concrete shall be subject to prior approval by the Building Official and shall comply with Sections 2.4.5.1 to 2.4.5.5.Admixtures shall conform following standards:
BDS EN 934-1 Admixtures for Concrete, Mortar and Grout-Part 1: Common Requirements.
BDS EN 934-2 Admixtures for Concrete, Mortar and Grout-Part 2: Concrete Admixtures Definitions, Requirements, Conformity, Marking and Labelling.
#### 2.3.5.1 Chloride
Calcium chloride or admixtures containing chloride from admixture ingredients shall not be used in prestressed concrete, concrete containing embedded aluminium in concrete cast against permanent galvanized metal forms, or in concrete exposed to severe or very severe sulphate-containing solutions (Sec 5.5.2.1 Part 6).
#### 2.3.5.2 Standards
Air-entraining admixtures shall conform to ASTM C260 Standard Specification for Airentraining Admixtures for Concrete. Water-reducing admixtures, retarding admixtures, accelerating admixtures, water-reducing and retarding admixtures, and water-reducing and accelerating admixtures shall conform to ASTM C494/C494M Chemical Admixtures for Concrete, or ASTM C1017/C1017M Chemical Admixtures for Use in Producing Flowing Concrete.
#### 2.3.5.3 Pozzolanas
Fly ash (Pulverized Fuel Ash) or other Pozzolanas used as admixtures shall conform to ASTM C618 Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolanas for Use in Concrete.
#### 2.3.5.4 Blast furnace slag
Ground granulated blast-furnace slag used as an admixture shall conform to ASTM C989 Standard Specification for Slag Cement for Use in Concrete and Mortars.
#### 2.3.5.5 Pigment for coloured concrete
Pigment for integrally coloured concrete shall conform to ASTM C979 Standard Specification for Pigments for Integrally Colored Concrete.
### **2.3.6 Metal Reinforcement**
Reinforcement and welding of reinforcement to be placed in concrete shall conform to the requirements of this Section.
* (a) Deformed Reinforcement: Deformed reinforcing bars shall conform to the following Standards; BDS ISO 6935-2:2010, Steel for the reinforcement of concrete-Part-2: Ribbed bars; Reinforcement conforming to the ASTM, Standards: A615/A615M Deformed and Plain Billet-Steel Bars; A616M, Rail-Steel Deformed and Plain Bars; A617M Axle-Steel Deformed and Plain Bars; A706M Low-Alloy Steel Deformed Bars; A767M Zinc Coated (Galvanized) Steel Bars; and A775M Epoxy-Coated Reinforcing Steel.
Deformed reinforcing bars with a specified yield strength exceeding 410 MPa may be used, provided $f_y$ shall be the stress corresponding to a strain of 0.35 percent and the bars otherwise conform to ASTM standards noted above. Fabricated deformed steel bar mats conforming to ASTM A184/A184M and deformed steel wire complying with ASTM A496/A496M may be used. Deformed wire for concrete reinforcement shall not be smaller than size D4 (nominal diameter: 5.72 mm), and for wire with a specified yield strength $f_y$ exceeding 410 MPa, $f_y$ shall be the stress corresponding to a strain of 0.35 percent.
Welded deformed steel wire fabric conforming to ASTM A497/A497M may be used; for a wire with specified yield strength $f_y$ exceeding 410 MPa, $f_y$ shall be the stress corresponding to a strain of 0.35 percent. Welded intersections shall not be spaced farther apart than 400 mm in direction of calculated stress, except for wire fabric used as stirrups.
* (b) Plain Reinforcement: Plain reinforcement shall conform to the following BDS and ASTM Standards. BDS ISO 6935-1:2010; ASTM A615/A615M; ASTM A996/A996M and ASTM A996/A996M. Steel welded wire, fabric plain reinforcement conforming to ASTM A185/A185M may be used, except that for wire with specified yield strength $f_y$ exceeding 410 MPa, $f_y$ shall be the stress corresponding to a strain of 0.35 percent. Welded intersections shall not be spaced farther apart than 300 mm in direction of calculated stress, except for wire fabric used as stirrups.
Smooth steel wire conforming to ASTM A182/A182M may be used in concrete; except that for a wire with specified yield strength $f_y$ exceeding 410 MPa, $f_y$ shall be the stress corresponding to a strain of 0.35 percent.
* (c) Cold-worked Steel Reinforcement: Cold-worked steel high strength bars shall conform to IS 1786 or BS 4461: 1978.
* (d) Pre-stressing Tendons: Wire, strands and bars for tendons in pre-stressed concrete shall conform to BDS: 240 Plain cold drawn steel wire; ASTM A416/A416M Steel Strand Uncoated Seven-Wire Stress Relieved; ASTM A421/A421M: Uncoated Stress Relieved Steel Wire; and ASTM A722/A722M: Uncoated High-Strength Steel Bar.
Wires, strands and bars not specifically listed in the above standards may be used, provided they conform to minimum requirements of these specifications and do not have properties that make them less satisfactory than those listed.
* (e) Structural Steel, Steel Pipe or Tubing: Structural steel used with reinforcing bars in composite compression members meeting the requirements of the Code shall conform to ASTM A36/A36M Structural Steel; ASTM A242/A242M High Strength Low-Alloy Structural Steel; ASTM A572/A572M High-Strength Low-Alloy Columbium-Vanadium Steel; and ASTM A588/A588M High-Strength Low-Alloy Structural Steel.
Steel pipe or tubing for composite compression members composed of a steel-encased concrete core meeting the requirements of this Code shall conform to ASTM A53/A53M Pipe, Steel, Black and Hot Dipped Zinc Coated Welded and Seamless; ASTM A500/A500M Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes; and ASTM A501 Hot-Formed Welded and Seamless Carbon Steel Structural Tubing.
### **2.3.7 Applicable Standards**
Materials used in concrete shall comply with the applicable standards listed below.
| Item | Description |
| --------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS 279 | Specification for Abrasion of Coarse Aggregates by Use of
Los Angeles Machine (under revision). |
| BDS 281 | Specification for Organic Impurities in Sands for Concrete
(under revision). |
| BDS 921 | Specification for Standard Sand for Testing of Cement. |
| BDS 240 | Specification for Plain Cold Drawn Steel Wire for Pre-
stressed Concrete. |
| BDS 243 | Specification for Coarse and Fine Aggregates from Natural
Sources for Concrete. |
| BDS ISO 1920-8 | Testing of Concrete-Part 8: Determination of Drying
Shrinkage of Concrete for Samples Prepared in the Field or
in the Laboratory. |
| BDS ISO 1920-9 | Testing of Concrete-Part 9: Determination of Creep of
Concrete Cylinders in Compression. |
| BDS ISO 1920-10 | Testing of Concrete-Part 10: Determination of Static
Modulus of Elasticity in Compression. |
| BDS ISO 22965-1 | Concrete-Part 1: Methods of Specifying and Guidance for
the Specifier. |
| BDS ISO 22965-2 | Concrete-Part 2: Specification of Constituent Materials,
Production of Concrete and Compliance of Concrete. |
| ASTM C31/C31M | Standard Practice for Making and Curing Concrete Test
Specimens in the Field. |
| ASTM C39/C39M | Standard Test Method for Compressive Strength of
Cylindrical Concrete Specimens. |
| ASTM C42/C42M | Standard Test Method for Obtaining and Testing Drilled
Cores and Sawed Beams of Concrete. |
| ASTM C78 | Standard Test Method for Flexural Strength of Concrete
(Using Simple Beam with Third-Point Loading) |
| ASTM C94/C94M | Standard Specification for Ready-Mixed Concrete. |
| ASTM C172 | Standard Practice for Sampling Freshly Mixed Concrete. |
| ASTM C192/C192M | Standard Practice for Making and Curing Concrete Test
Specimens in the Laboratory. |
| ASTM C317/C317M | Standard Specification for Gypsum Concrete. |
| ASTM C496/C496M | Standard Test Method for Splitting Tensile Strength of
Cylindrical Concrete Specimens. |
| ASTM C617 | Standard
Practice
for
Capping
Cylindrical
Concrete
Specimens. |
| ASTM C685/C685M | Standard Specification for Concrete Made by Volumetric
Batching and Continuous Mixing. |
| ASTM C989 | Standard Specification for Slag Cement for Use in Concrete
and Mortars. |
### **2.3.8 Concrete Pipe and Precast Sections**
Concrete pipes and precast sections shall conform to the Standards listed below:
| Item | Description |
| ----------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| BDS 1626 | Concrete pipes (with and without) reinforcement. |
| ASTM C14M | Standard Specification for Non-reinforced Concrete Sewer,
Storm Drain, and Culvert Pipe (Metric). |
| ASTM C76M | Standard Specification for Reinforced Concrete Culvert, Storm
Drain, and Sewer Pipe (Metric). |
| ASTM C361M | Standard Specification for Reinforced Concrete Low-Head
Pressure Pipe (Metric). |
| ASTM C444M | Standard Specification for Perforated Concrete Pipe (Metric). |
| ASTM C478M | Standard Specification for Precast Reinforced Concrete
Manhole Sections (Metric). |
| ASTM C507M | Standard Specification for Reinforced Concrete Elliptical
Culvert, Storm Drain, and Sewer Pipe (Metric). |
| ASTM C654M | Standard Specification for Porous Concrete Pipe (Metric). |
| ASTM C655M | Standard Specification for Reinforced Concrete D-Load
Culvert, Storm Drain, and Sewer Pipe (Metric). |
| ASTM C1433M | Standard Specification for Precast Reinforced Concrete
Monolithic Box Sections for Culverts, Storm Drains, and
Sewers (Metric). |
| ASTM C858 | Standard Specification for Underground Precast Concrete
Utility Structures. |
| ASTM C891 | Standard Practice for Installation of Underground Precast
Concrete Utility Structures. |
| ASTM C913 | Standard Specification for Precast Concrete Water and
Wastewater Structures. |
| ASTM C924M | Standard Practice for Testing Concrete Pipe Sewer Lines by
Low-Pressure Air Test Method (Metric). |
| IS 458 | Specification for precast concrete pipes with and without
reinforcement. |
| IS 784 | Specification for pre-stressed concrete pipes. |
| IS 1916 | Specification for steel cylinder pipe with concrete lining and
coating. |
| IS 3597 | Methods of test for concrete pipes. |
| IS 4350 | Specification for concrete porous pipes for under drainage. |
| IS 7319 | Specification for perforated concrete pipes. |
| IS 7322 | Specification for specials for steel cylinder reinforced concrete
pipes. |
## **2.4 Pre-Stressed Concrete**
### **2.4.1 Concrete for Pre-stressed Concrete**
Cement and concrete required for pre-stressed concrete are elaborately described in Sec 2.3 of this Part. BDS and other standards for concrete as a material are also contained in the same section.
### **2.4.2 Steel for Pre-stressed Concrete**
Steel and tendons for pre-stressed concrete along with the BDS and other standard requirements are included in Sec 2.8 of this Part.
Steel material for pre-stressed concrete shall also conform following Standards.
| Item | Description |
| -------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS ISO 6934-1 | Steel for the prestressing of concrete-Part 1: General
requirements. |
| BDS ISO 6934-2 | Steel for the prestressing of concrete-Part 2: Cold-drawn
wire. |
| BDS ISO 6934-3 | Steel for the prestressing of concrete-Part 3: Quenched and
tempered wire. |
| BDS ISO 6934-4 | Steel for the prestressing of concrete-Part 4: Strand. |
| BDS ISO 6934- 5 | Steel for the Prestressing of concrete-Part 5: Hot-rolled steel
bars with or without subsequent processing. |
| BDS ISO 6935
(Part-1) | Steel for the reinforcement of concrete-Part-1: Plain bars. |
| BDS ISO 6935
(Part-2) | Steel for the reinforcement of concrete-Part-2: Ribbed bars. |
| BDS ISO 6935
(Part-3) | Steel for the reinforcement of concrete-Part-3: Welded
fabric. Specifies technical requirements for factory made
sheets or rolls welded fabric manufacture from steel wires or
bars with diameters from 4 mm to 16 mm and designed for
reinforcement in ordinary concrete structured and for non-
prestressed reinforcement in prestressed concrete structures. |
| BDS ISO 10065 | Steel bars reinforcement of concrete bend and re-bend tests. |
| BDS ISO 15835-1 | Steel for the reinforcement of concrete-Reinforcement
couplers
for
mechanical
splices
of
bars-Part
1:
Requirements. |
| BDS ISO 15835-2 | Steel for the reinforcement of concrete-Reinforcement
couplers for mechanical splices of bars-Part 2: Test methods. |
| BDS ISO 10144 | Certification scheme for steel bars and wires for the
reinforcement of concrete structures. |
| BDS ISO 15630-1 | Steel for the reinforcement and Prestressing of concrete-Test
methods-Part 1: Reinforcing bars, wire rod and wire. |
| BDS ISO 15630-2 | Steel for the reinforcement and prestressing of concrete-Test
methods-Part 2: Welded fabric. |
| BDS ISO 15630-3 | Steel for the Reinforcement and prestressing of concrete-
Test methods-Part 3: Prestressing steel. |
| BDS ISO 16020 | Steel for the reinforcement and prestressing of concrete-
Vocabulary. |
## **2.5 Building Limes**
### **2.5.1 Types of Lime**
According to the degree of calcinations, slaking and setting actions and depending upon the nature and amount of foreign matters associated with, the limes are classified as: (i) High calcium, fat, rich, common or pure lime; (ii) Lean, meager or poor lime; and (iii) Hydraulic or water lime
### **2.5.2 Properties of Lime**
A good lime should slake readily in water, dissolve in soft water, free from fuel ashes and unburnt particles and have good setting power under water.
Building limes shall comply with the following ASTM standard specifications: ASTM C206 Finishing Hydrated Lime; ASTM C207 Hydrated Lime for Masonry Purposes; ASTM C141/C141M Hydraulic Hydrated Lime for Structural Purposes; ASTM C977 Quicklime and Hydrated Lime for Soil Stabilization; and ASTM C5 Quicklime for Structural Purposes.
The following Indian Standards may also be accepted for lime concrete and testing of building limes:
| Item | Description |
| -------- | -------------------------------------------------------------------------------------------- |
| IS712 | Specification for building limes. |
| IS1624 | Method of field testing of building lime. |
| IS 2686 | Specification for cinder aggregates for use in lime concrete. |
| IS 3068 | Specification for broken brick (burnt clay) coarse aggregates for
use in lime concrete. |
| IS 3115 | Specification for lime-based blocks. |
| IS 3182 | Specification for broken brick (burnt clay) fine aggregates for use
in lime mortar. |
| IS 4098 | Specification for lime-pozzolana mixture. |
| IS 4139 | Specification for sand-lime bricks. |
| IS 6932 | Method of tests for building limes. (Parts I to XI) |
| IS 10360 | Specification for lime-pozzolana concrete blocks for paving. |
| IS 10772 | Specification for quick setting lime pozzolana mixture. |
| IS 12894 | Specification for pulverized fuel ash lime bricks. |
## **2.6 Gypsum Based Materials and Plaster**
### **2.6.1 Gypsum Board**
Gypsum wallboard, gypsum sheathing, gypsum base for gypsum veneer plaster, exterior gypsum soffit board, pre-decorated gypsum board or water resistant gypsum backing board complying with the standards listed below.
### **2.6.2 Gypsum Plaster**
A mixture of calcined gypsum or calcined gypsum and lime and aggregate and other approved materials as specified in this Code.
### **2.6.3 Gypsum Veneer Plaster**
Gypsum plaster applied to an approved base in one or more coats normally not exceeding 1/4 inch (6.4 mm) in total thickness.
### **2.6.4 Cement Plaster**
A mixture of Portland or blended cement, Portland cement or blended cement and hydrated lime, masonry cement or plastic cement and aggregate and other approved materials as specified in this Code.
Gypsum building materials shall conform to the Standards listed below.
| Item | Description |
| ---------------------- | ----------------------------------------------------------------------------------------------- |
| ASTM C22/C22M | Standard Specification for Gypsum. |
| ASTM C28/C28M | Standard Specification for Gypsum Plasters. |
| ASTM C35 | Standard Specification for Inorganic Aggregates for Use in
Gypsum Plaster. |
| ASTM C59/C59M | Standard Specification for Gypsum Casting Plaster and
Gypsum Molding Plaster. |
| ASTM C317/
C317M | Standard Specification for Gypsum Concrete. |
| ASTM C471M | Standard Test Methods for Chemical Analysis of Gypsum and
Gypsum Products. |
| ASTM C472 | Standard Test Methods for Physical Testing of Gypsum,
Gypsum Plasters and Gypsum Concrete. |
| ASTM C473 | Standard Test Methods for Physical Testing of Gypsum Panel
Products. |
| ASTM C474 | Standard Test Methods for Joint Treatment Materials for
Gypsum Board Construction. |
| ASTM C587 | Standard Specification for Gypsum Veneer Plaster. |
| ASTM
C1396/C1396M | Standard Specification for Gypsum Board. |
| IS 2849-1983 | Specification for non-load bearing gypsum partition blocks
(solid and hollow types). |
## **2.7 Flooring Materials**
### **2.7.1 General**
Flooring materials are generally of two types; precast systems like tiles, bricks and cast in-situ.
### **2.7.2 Concrete/Terrazzo Tiles**
Concrete/Terrazzo tiles shall have good abrasion and impact resistance properties. Factors such as the type of cement and the type and grading of aggregate used, influence the resistance of such tiles to chemicals including cleaning agents. Terrazzo tiles shall have a wear layer after grinding at least 6 mm composed of graded marble chipping in white, tinted or grey Portland cement on a layer of fine concrete. They may be ground
after manufacture to expose the marble aggregate and subsequently grouted. Slip resisting grits may be incorporated. These tiles shall conform to BDS EN 13748-1:2008 Terrazzo tiles-Part 1: Terrazzo tiles for internal use; BDS EN 13748-2:2008 Terrazzo tiles-Part 2: Terrazzo tiles for external use; BDS 1262: 1990 Clay flooring tiles; BDS 1248: 1989 Ceramic unglazed vitreous acid resistant tiles or IS: 1237, Specification for cement concrete flooring tile.
### **2.7.3 Asphalt Tiles/Flooring**
Asphalt tiles/floorings are suitable for industrial flooring in areas where they will not be exposed to solvents, grease, oil, corrosive chemicals and excessive heat. Bitumen mastic for flooring shall conform to IS: 1195; IS: 8374 Bitumen Mastic, Anti-static and Electrically Conducting Grade and IS: 9510 Bitumen Mastic Acid Resisting Grade.
### **2.7.4 Mosaic Tiles**
Mosaic tiles of a variety of shapes and sizes may be used. Thickness of the wear layer is dependent on the sizes of marble chips but shall not be less than 6 mm thick. The tiles shall be wet cured for sufficient time before laying so that their surfaces are not damaged during grinding and polishing.
### **2.7.5 Clay Tile**
Clay floor tiles shall have sufficient strength and abrasion resistant characteristics to withstand the impact and abrasion they are likely to be subject to. When glazed earthenware tiles are used in flooring they shall conform to IS: 777 Glazed Earthenware Tiles.
### **2.7.6 Vinyl Tiles**
The vinyl tiles shall consist of a thoroughly blended composition of thermoplastic binder, asbestos fibre, fillers and pigments. The thermoplastic binder shall consist substantially of either or both of the following:
* (a) Vinyl chloride polymer
* (b) Vinyl chloride copolymers.
The polymeric material shall be compounded with suitable plasticizers and stabilizers. The tiles may be plain, patterned or mottled. The thickness shall not be less than 1.5 mm.
### **2.7.7 Rubber Tiles**
These tiles are composed of natural, synthetic or reclaimed rubber, or a combination of these, with reinforcing fibres, pigments, and fillers, vulcanized and molded under pressure. The tiles shall have excellent resilience and resistance to indentation, and good resistance to grease, alkali and abrasion. The thickness shall not be less than 2 mm.
### **2.7.8 Cast In-situ Floor Coverings**
* (a) Terrazzo: Terrazzo is a marble mosaic with Portland cement matrix and is generally composed of two parts marble chips to one part Portland cement. Color pigments may be added. The thickness of terrazzo topping may vary from 13 mm to 19 mm and may be applied to green concrete of the floor or bonded with neat Portland cement, or over a sand cushion placed on the concrete floor.
* (b) Concrete: A concrete topping may be applied to a concrete structural slab before or after the base slab has hardened. Integral toppings may generally be 25 mm to 40 mm thick; independent toppings about 25 mm to 50 mm thick. Aggregate sizes shall not exceed 6 mm.
### **2.7.9 Other Flooring Materials**
Other flooring materials i.e. bricks, natural stone, etc. showing satisfactory performance in similar situations may be allowed. Plastic flooring tile and ceramic unglazed vitreous acid resistant tiles, if used, shall conform to IS: 3464 and IS: 4357 respectively.
Flooring compositions complying with IS: 657, Materials for use in the manufacture of magnesium oxychloride flooring composition; and IS: 9197, Epoxy resin composition for floor topping may be allowed. Linoleum sheets and tiles shall conform to IS: 653.
Flooring materials shall also conform to the standards listed below.
* BDS 1248 Ceramic unglazed vitreous acid resistant tiles seat covers the requirements for ceramic unglazed vitreous acid resistant tiles used in lying of floors & lining of tanks subjected to corrosive conditions. Manufacture, Finish, Tests etc.
* BDS 1262 Clay flooring tiles.
Specifies the requirements for dimensions, quality & strength for clay flooring tiles & different types of tests.
| Item | Description |
| ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS ISO
10545 ‐ 1 | Ceramic tiles, Sampling and basis for acceptance.
Specifies rules for batching, sampling, inspection and acceptance/
rejection of ceramic tiles. |
| BDS ISO
10545 ‐ 2 | Ceramic tiles, Determination of dimensions and surface quality.
Specifies methods for determining the dimensional characteristics
(length, width, thickness, straightness of sides, rectangularity, and
surface flatness) and the surface of ceramic tiles. |
| BDS ISO
10545 ‐ 3 | Ceramic tiles, Determination of water absorption, apparent
porosity, apparent relative density and bulk density. |
| | Specifies methods for determining water absorption, apparent
porosity, apparent relative density and bulk density of ceramic
tiles. |
| BDS ISO
10545 ‐ 4 | Ceramic tiles, Determination of modulus of rupture and breaking
strength
Defines a test method for determining the modulus of rupture and
breaking strength of all ceramic tiles. |
| BDS ISO
10545 ‐ 5 | Ceramic tiles, Determination of impact resistance by measurement
of coefficient of restitution |
| | Specifies methods for determining the impact resistance of ceramic
tiles by measuring the coefficient of restitution. |
| BDS ISO 10545‐
6 |
Ceramic tiles, Determination of resistance to deep abrasion for
unglazed tiles. |
| BDS ISO
10545 ‐ 7 | Ceramic tiles, Determination of resistance to surface abrasion for
glazed tiles. |
| | Specifies a method for determining the resistance to surface
abrasion of all glazed ceramic tiles used for floor covering. |
| BDS ISO
10545 ‐ 8 | Ceramic tiles, Determination of linear thermal expansion |
| | Defines a test method for determining the coefficient of linear
thermal expansion of ceramic tiles. |
| BDS ISO
10545 ‐ 9 | Ceramic tiles, Determination of resistance to thermal shock. |
| | Defines a test method for determining the resistance to thermal
shock of all ceramic tiles under normal conditions of use. |
| BDS ISO Ceramic tiles, Determination of moisture expansion. 10545 ‐ 10 Specifies a method for determining the moisture expansion of all ceramic tiles. BDS ISO Ceramic tiles, Determination of crazing resistance for glazed tiles. 10545 ‐ 11 Defines a test method for determining the crazing resistance of all glazed ceramic tiles except when the crazing is an inherent decorative feature of the product. BDS ISO Ceramic tiles, Determination of frost resistance. 10545 ‐ 12 Specifies a method for determining the frost resistance of all ceramic tiles intended for use in freezing conditions in the presence of water. BDS ISO Ceramic tiles, Determination of chemical resistance. 10545 ‐ 13 Specifies a test method for determining the chemical resistance of all ceramic tiles at room temperature. The method is applicable to all types of ceramic tiles. BDS ISO Ceramic tiles, Determination of resistance to stains. 10545 ‐ 14 Specifies a method for determining the resistance to stains of the proper surface of ceramic tiles. BDS ISO Ceramic tiles, Determination of lead and cadmium given off by 10545 ‐ 15 glazed tiles. | |
Specifies a method for the determination of lead and cadmium given off by the glaze of ceramic tiles.
BDS ISO Ceramic tiles, Determination of small color differences. 10545 ‐ 16 Describes a method for utilizing color measuring instruments for quantifying the small color differences between plain colored glazed ceramic tiles, which are designed to be uniform and consistent color. It permits the specification of a maximum acceptable value which depends only on the closeness of match and not on the nature of the color difference.
| Item | Description |
| --------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS EN 490 | Concrete roofing tiles and fittings for roof covering and all
cladding-Product specifications. |
| BDS ISO 13006 | Ceramic tiles ‐ Definitions, classification, characteristics and
marking. |
| | This Standard defines terms and establishes classifications
characteristics and marking requirements for ceramic tiles of the
best commercial quality (first quality). |
| BDS EN 491 | Concrete roofing tiles and fittings for roof covering and wall
cladding-Test methods. |
| BDS EN 538 | Clay roofing tiles for discontinuous laying-Flexural strength test. |
| BDS EN
539 ‐ 1 | Clay roofing tiles for discontinuous laying. Determination of
physical characteristics-Part 1: Impermeability test. |
| BDS EN 1024 | Clay roofing tiles for discontinuous laying-Determination of
geometric characteristics. |
| BDS EN 1304 | Clay
roofing
tiles
and
fittings-Product
definitions
and
specifications. |
| BDS EN
13748 ‐ 1 | Terrazzo tiles-Part 1: Terrazzo tiles for internal use. |
| BDS EN
13748 ‐ 2 | Terrazzo tiles-Part 2: Terrazzo tiles for external use. |
## **2.8 Steel**
### **2.8.1 Reinforcing Steel**
Reinforcing steel shall comply with the requirements specified in Sec 2.4.6 in this Part.
### **2.8.2 Structural Steel**
Structural steel shall conform to Bangladesh Standards BDS 878: 1978, Specification for weld able structural steels; BDS 1355: 1992, Dimensions and properties of hot rolled steel beam, column, channel and angle sections. Where Bangladesh standards are not available, the relevant standards listed below shall be applicable.
BDS 1429 Light gauge steel sections.
BDS ISO 2566-1 Steel-Conversion of elongation values-Part 1: Carbon and low alloy steels.
| Item | Description |
| ----------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS ISO 2566-2 | Steel-Conversion of elongation values-Part 2: Austenitic steels. |
| BDS ISO 657-1 | Hot-rolled steel sections-Part 1: Equal-leg angles-Dimensions. |
| BDS ISO 657-2 | Hot-rolled
steel
sections-Part
2:
Unequal-leg
angles-
Dimensions. |
| BDS ISO 657-5 | Hot-rolled steel sections-Part V Equal-leg angles and unequal
leg angles-Tolerances for metric and inch series. |
| BDS ISO 657-11 | Hot-rolled steel sections-Part 11: Sloping flange channel
sections (Metric series)-Dimensions and sectional properties. |
| BDS ISO 657-15 | Hot-rolled steel sections-Part 15 Sloping flange beam sections
(Metric series)-Dimensions and sectional properties. |
| BDS ISO 657-16 | Hot-rolled steel sections-Part 16: Sloping flange column
sections (metric series)-Dimensions and sectional properties. |
| BDS ISO 657-18 | Hot-rolled steel sections-Part 18: L sections for shipbuilding
(metric series) 104-Dimensions, sectional properties and
tolerances. |
| BDS ISO 657-19 | Hot-rolled steel sections-Part 19: Bulb flats (metric series)-
Dimensions, sectional properties and tolerances. |
| BDS ISO 657-21 | Hot-rolled steel sections-Part 21 T-sections with equal depth
and flange width-Dimensions. |
| BDS ISO 10474 | Steel and steel products-Inspection documents. |
| BDS ISO 14284 | Steel and iron-Sampling and preparation of samples for the
determination of chemical composition. |
| BDS ISO 9769 | Steel and iron-Review of available methods of analysis. |
| BDS ISO 6929 | Steel products-Definition and classification. |
| BDS ISO 20723 | Structural steels-Surface condition of hot-rolled sections-
Delivery requirements. |
| BDS ISO 24314 | Structural steels-Structural steels for building with improved
seismic resistance-Technical delivery conditions. |
| BDS ISO 404 | Steel
and
steel
products-General
technical
delivery
requirements. |
| BDS ISO 1127 | Stainless steel tubes-Dimensions, tolerances and conventional
masses per unit length. |
| BDS ISO 4200 | Plain end steel tubes, welded and seamless-General tables of
dimensions and masses per unit length. |
| BDS ISO 6761 | Steel tubes-Preparation of ends of tubes and fittings for
welding. |
| ASTM A27/A27M | Standard Specification for Steel Castings, Carbon, for General
Application. |
| ASTM A36/A36M | Standard Specification for Carbon Structural Steel. |
| ASTM A48/A48M | Standard Specification for Gray Iron Castings. |
| ASTM A53/A53M | Standard Specification for Pipe, Steel, Black and Hot-Dipped,
Zinc-Coated, Welded and Seamless. |
| ASTM A148/A148M | Standard Specification for Steel Castings, High Strength, for
Structural Purposes. |
| ASTM A242/A242M | Standard Specification for High-Strength Low-Alloy Structural
Steel. |
| ASTM A252 | Standard Specification for Welded and Seamless Steel Pipe
Piles. |
| ASTM A283/A283M | Standard Specification for Low and Intermediate Tensile
Strength Carbon Steel Plates. |
| ASTM A307 | Standard Specification for Carbon Steel Bolts and Studs,
60,000 psi Tensile Strength. |
| ASTM A325 | Standard Specification for Structural Bolts, Steel, Heat Treated,
120/105 ksi Minimum Tensile Strength. |
| ASTM A325M | Standard Specification for Structural Bolts, Steel, Heat Treated
830 MPa Minimum Tensile Strength \[Metric]. |
| ASTM A336/A336M | Standard Specification for Alloy Steel Forgings for Pressure
and High-Temperature Parts. |
| ASTM A653/A653M | Standard
Specification
for
Steel
Sheet,
Zinc-Coated
(Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the
Hot-Dip Process. |
| ASTM A449 | Standard Specification for Hex Cap Screws, Bolts and Studs,
Steel, Heat Treated, 120/105/90 ksi Minimum Tensile Strength,
General Use. |
| ASTM A490 | Standard Specification for Structural Bolts, Alloy Steel, Heat
Treated, 150 ksi Minimum Tensile Strength. |
| ASTM A500/A500M | Standard Specification for Cold-Formed Welded and Seamless
Carbon Steel Structural Tubing in Rounds and Shapes. |
| ASTM A501 | Standard Specification for Hot-Formed Welded and Seamless
Carbon Steel Structural Tubing. |
| ASTM A514/A514M | Standard Specification for High-Yield-Strength, Quenched and
Tempered Alloy Steel Plate, Suitable for Welding. |
| ASTM A529/A529M | Standard Specification for High-Strength Carbon-Manganese
Steel of Structural Quality. |
| ASTM A563 | Standard Specification for Carbons and Alloy Steel Nuts. |
| ASTM A563M | Standard Specification for Carbon and Alloy Steel Nuts
\[Metric]. |
| ASTM A1011/A1011M | Standard Specification for Steel, Sheet and Strip, Hot-Rolled, Carbon, Structural, High-Strength Low-Alloy, High-Strength
Low-Alloy with Improved Formability, and Ultra-High
Strength. |
| ASTM A572/A572M | Standard
Specification
for
High-Strength
Low-Alloy
Columbium-Vanadium Structural Steel. |
| ASTM A588/A588M | Standard Specification for High-Strength Low-Alloy Structural
Steel, up to 50 ksi \[345 MPa] Minimum Yield Point, with
Atmospheric Corrosion Resistance. |
| ASTM A606/A606M | Standard Specification for Steel, Sheet and Strip, High-
Strength, Low-Alloy, Hot-Rolled and Cold-Rolled, with
Improved Atmospheric Corrosion Resistance. |
| ASTM A1008/A1008M | Standard Specification for Steel, Sheet, Cold-Rolled, Carbon, Structural, High-Strength Low-Alloy, High-Strength Low-
Alloy with Improved Formability, Solution Hardened, and Bake
Harden able. |
| ASTM A618/A618M | Standard Specification for Hot-Formed Welded and Seamless
High-Strength Low-Alloy Structural Tubing. |
| ASTM A666 | Standard
Specification
for
Annealed
or
Cold-Worked
Austenitic Stainless Steel Sheet, Strip, Plate, and Flat Bar. |
| ASTM A668/A668M | Standard Specification for Steel Forgings, Carbon and Alloy,
for General Industrial Use. |
| ASTM A690/A690M | Standard Specification for High-Strength Low-Alloy Nickel,
Copper, Phosphorus Steel H-Piles and Sheet Piling with
Atmospheric Corrosion Resistance for Use in Marine
Environments. |
| ASTM A852/A852M | Standard Specification for Quenched and Tempered Low-Alloy
Structural Steel Plate with 70 ksi \[485 MPa] Minimum Yield
Strength to 4 in. \[100 mm] Thick. |
### **2.8.3 Steel Plate, Sheet and Strips**
These shall conform to the following standards.
| Item | Description |
| -------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS 868 : 1978 | Code of practice for galvanized corrugated sheet roof and wall
coverings. |
| BDS 1122: 1985 | Specification for hot-dip galvanized steel sheet and coil. |
| BDS ISO 9328-1 | Steel flat products for pressure purposes-Technical delivery
conditions-Part 1: general requirements. |
| BDS ISO 9328-2 | Steel flat products for pressure purposes-Technical delivery
conditions-Part 2: Non-alloy and alloy steels with specified
elevated temperature properties. |
| BDS ISO 9328-3 | Steel flat products for pressure purposes-Technical delivery
conditions -Part 3: Weldable fine grain steels, normalized. |
| BDS ISO 9328-4 | Steel flat products for pressure purposes-Technical delivery
conditions-Part 4: Nickel-alloy steels with specified low
temperature properties. |
| BDS ISO 9328-5 | Steel flat products for pressure purposes-Technical delivery
conditions-Part 5: Weldable fine grain steels, thermo
mechanically rolled. |
| BDS ISO 9328-6 | Steel flat products for pressure purposes-Technical delivery
conditions-Part 6: Weldable fine grain steels, quenched and
tempered. |
| BDS ISO 9328-7 | Steel flat products for pressure purposes-Technical delivery
conditions-Part 7: Stainless steels. |
| BDS ISO 4995 | Hot-rolled steel sheet of structural quality. |
| BDS ISO 7452 | Hot-rolled structural steel plates-Tolerances on dimensions
and shape. |
| BDS ISO 7778 | Steel plate with specified through-Thickness characteristics. |
| BDS ISO 7788 | Steel-Surface finish of hot-rolled plates and wide flats-
Delivery requirements. |
| BDS ISO 9034 | Hot-rolled
structural
steel
wide
flats-Tolerances
on
dimensions and shape. |
| BDS ISO 9364 | Continuous hot-dip aluminum/zinc coated steel sheet of
commercial, drawing and structural qualities. |
| BDS ISO 16160 | Continuously hot-rolled steel sheet products-Dimensional and
shape tolerances. |
| BDS ISO16162 | Continuously cold-rolled steel sheet products-Dimensional
and shape tolerances. |
| BDS ISO 16163 | Continuously hot-dipped coated steel sheet products-
Dimensional and shape tolerances. |
| IS 412 | Specification for expanded metal steel sheets for general
purposes. |
| IS 1079 | Specification for hot rolled carbon steel sheet and strip. |
| IS 4030 | Specification for cold-rolled carbon steel strip for general
engineering purposes. |
| IS 7226 | Specification for cold-rolled medium, high carbon and low-
alloy steel strip for general engineering purposes. |
| IS 3502 | Specification for steel chequered plates. |
| ASTM
A109/A109M | Standard Specification for Steel, Strip, Carbon (0.25
Maximum Percent), Cold-Rolled. |
| ASTM A123/A123M | Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products. |
| ASTM A167 | Standard Specification for Stainless and Heat-Resisting
Chromium-Nickel Steel Plate, Sheet, and Strip. |
| ASTM A176 | Standard Specification for Stainless and Heat-Resisting
Chromium Steel Plate, Sheet, and Strip. |
| ASTM A240/A240M | Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and
for General Applications. |
| ASTM A263 | Standard Specification for Stainless Chromium Steel-Clad
Plate. |
| ASTM A264 | Specification for Stainless Chromium-Nickel Steel-Clad Plate. |
| ASTM
A285/A285M | Standard Specification for Pressure Vessel Plates, Carbon
Steel, Low- and Intermediate-Tensile Strength. |
| ASTM
A328/A328M | Standard Specification for Steel Sheet Piling. |
| ASTM A1008/A1008M | Standard Specification for Steel, Sheet, Cold-Rolled, Carbon, Structural, High-Strength Low-Alloy, High-Strength Low-
Alloy with Improved Formability, Solution Hardened, and
Bake Harden able. |
| ASTM A414/A414M | Standard Specification for Steel, Sheet, Carbon, and High-Strength, Low-Alloy for Pressure Vessels. |
| ASTM A424/A424M | Standard Specification for Steel, Sheet, for Porcelain Enameling. |
| ASTM A929/A929M | Standard Specification for Steel Sheet, Metallic-Coated by the Hot-Dip Process for Corrugated Steel Pipe. |
| ASTM A463/A463M | Standard Specification for Steel Sheet, Aluminum-Coated, by the Hot-Dip Process. |
| ASTM
A480/A480M | Standard Specification for General Requirements for Flat-
Rolled Stainless and Heat-Resisting Steel Plate, Sheet, and
Strip. |
| ASTM A505 | Standard Specification for Steel, Sheet and Strip, Alloy, Hot-
Rolled and Cold-Rolled, General Requirements for. |
| ASTM A506 | Standard Specification for Alloy and Structural Alloy Steel,
Sheet and Strip, Hot-Rolled and Cold-Rolled. |
| ASTM A507 | Standard Specification for Drawing Alloy Steel, Sheet and
Strip, Hot-Rolled and Cold-Rolled. |
| ASTM
A568/A568M | Standard Specification for Steel, Sheet, Carbon, Structural,
and High-Strength, Low-Alloy, Hot-Rolled and Cold-Rolled,
General Requirements for. |
| ASTM
A577/A577M | Standard
Specification
for
Ultrasonic
Angle-Beam
Examination of Steel Plates. |
| ASTM
A578/A578M | Standard
Specification
for
Straight-Beam
Ultrasonic
Examination of Rolled Steel Plates for Special Applications. |
| ASTM
A879/A879M | Standard Specification for Steel Sheet, Zinc Coated by the
Electrolytic Process for Applications Requiring Designation
of the Coating Mass on Each Surface. |
| ASTM
A599/A599M | Standard Specification for Tin Mill Products, Electrolytic Tin-
Coated, Cold-Rolled Sheet. |
| ASTM
A606/A606M | Standard Specification for Steel, Sheet and Strip, High-
Strength, Low-Alloy, Hot-Rolled and Cold-Rolled, with
Improved Atmospheric Corrosion Resistance. |
| ASTM
A635/A635M | Standard Specification for Steel, Sheet and Strip, Heavy-
Thickness Coils, Hot-Rolled, Alloy, Carbon, Structural, High-
Strength Low-Alloy, and High-Strength Low-Alloy with
Improved Formability, General Requirements for. |
| ASTM
A653/A653M | Standard
Specification
for
Steel
Sheet,
Zinc-Coated
(Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by
the Hot-Dip Process. |
| ASTM A666 | Standard Specification for Annealed or Cold-Worked
Austenitic Stainless Steel Sheet, Strip, Plate, and Flat Bar. |
| ASTM
A690/A690M | Standard Specification for High-Strength Low-Alloy Nickel,
Copper, Phosphorus Steel H-Piles and Sheet Piling with
Atmospheric Corrosion Resistance for Use in Marine
Environments. |
| ASTM A775/A775M | Standard Specification for Epoxy-Coated Steel Reinforcing Bars. |
| ASTM A792/A792M | Standard Specification for Steel Sheet, 55 % Aluminum-Zinc Alloy-Coated by the Hot-Dip Process. |
| ASTM A857/A857M | Standard Specification for Steel Sheet Piling, Cold Formed, Light Gage. |
| ASTM A875/A875M | Standard Specification for Steel Sheet, Zinc-5% Aluminum Alloy-Coated by the Hot-Dip Process. |
### **2.8.4 Steel Pipe, Tube and Fittings**
These items shall conform to the following Standards:
| Item | Description |
| -------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| BDS ISO 49 | Malleable cast iron fittings threaded to ISO 7-1. |
| BDS ISO 3419 | Non-alloy and alloy steel butt-welding fittings. |
| BDS ISO 3545-3 | Steel tubes and fittings-Symbols for use in specifications-Part
3: Tubular fittings with circular cross-section. |
| BDS ISO 4144 | Pipe work-Stainless steel fittings threaded in accordance with
ISO 7-1. |
| BDS ISO 4145 | Non-alloy steel fittings threaded to ISO 7-1. |
| BDS ISO 5251 | Stainless steel butt-welding fittings. |
| ASTM A53/A53M | Standard Specification for Pipe, Steel, Black and Hot-Dipped,
Zinc-Coated, Welded and Seamless. |
| ASTM A105/A105M | Standard Specification for Carbon Steel Forgings for Piping Applications. |
| ASTM A106/A106M | Standard Specification for Seamless Carbon Steel Pipe for High-Temperature Service. |
| ASTM A134 | Standard Specification for Pipe, Steel, Electric-Fusion (Arc)-
Welded (Sizes NPS 16 and Over). |
| ASTM A139/A139M | Standard Specification for Electric-Fusion (Arc)-Welded Steel Pipe (NPS 4 and Over). |
| ASTM A181/A181M | Standard Specification for Carbon Steel Forgings, for General-Purpose Piping. |
| ASTM A182/A182M | Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and
Parts for High-Temperature Service. |
| ASTM A234/A234M | Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature
Service. |
| ASTM A252 | Standard Specification for Welded and Seamless Steel Pipe
Piles. |
| ASTM A254 | Standard Specification for Copper-Brazed Steel Tubing. |
| ASTM A268/A268M | Standard Specification for Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing for General Service. |
| ASTM A269 | Standard Specification for Seamless and Welded Austenitic
Stainless Steel Tubing for General Service. |
| ASTM A270 | Standard Specification for Seamless and Welded Austenitic
Stainless Steel Sanitary Tubing. |
| ASTM A312/A312M | Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes. |
| ASTM A333/A333M | Standard Specification for Seamless and Welded Steel Pipe for Low-Temperature Service. |
| ASTM A334/A334M | Standard Specification for Seamless and Welded Carbon and Alloy-Steel Tubes for Low-Temperature Service. |
| ASTM A403/A403M | Standard Specification for Wrought Austenitic Stainless Steel Piping Fittings. |
| ASTM A420/A420M | Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Low-Temperature Service. |
| ASTM A423/A423M | Standard Specification for Seamless and Electric-Welded Low-Alloy Steel Tubes. |
| ASTM
A450/A450M | Standard Specification for General Requirements for Carbon
and Low Alloy Steel Tubes. |
| ASTM A500/A500M | Standard Specification for Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes. |
| ASTM A50 | Standard Specification for Hot-Formed Welded and Seamless
Carbon Steel Structural Tubing. |
| ASTM A522/A522M | Standard Specification for Forged or Rolled 8 and 9% Nickel Alloy Steel Flanges, Fittings, Valves, and Parts for Low-
Temperature Service. |
| ASTM A524 | Standard Specification for Seamless Carbon Steel Pipe for
Atmospheric and Lower Temperatures. |
| ASTM
A530/A530M | Standard
Specification
for
General
Requirements
for
Specialized Carbon and Alloy Steel Pipe. |
| ASTM
A589/A589M | Standard Specification for Seamless and Welded Carbon Steel
Water-Well Pipe. |
| ASTM
A618/A618M | Standard Specification for Hot-Formed Welded and Seamless
High-Strength Low-Alloy Structural Tubing. |
| ASTM A632 | Standard Specification for Seamless and Welded Austenitic
Stainless Steel Tubing (Small-Diameter) for General Service. |
| ASTM
A707/A707M | Standard Specification for Forged Carbon and Alloy Steel
Flanges for Low-Temperature Service. |
| ASTM A733 | Standard Specification for Welded and Seamless Carbon Steel
and Austenitic Stainless Steel Pipe Nipples. |
| ASTM A778 | Standard Specification for Welded, Un-annealed Austenitic
Stainless Steel Tubular Products. |
| ASTM A807/A807M | Standard Practice for Installing Corrugated Steel Structural Plate Pipe for Sewers and Other Applications. |
| ASTM A865/A865M | Standard Specification for Threaded Couplings, Steel, Black or Zinc-Coated (Galvanized) Welded or Seamless, for Use in
Steel Pipe Joints. |
### **2.8.5 Steel Bars, Wire and Wire Rods**
These shall conform to the following Standards.
| Item | Description |
| --------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS ISO 1035-1 | Hot-rolled steel bars-Part 1: Dimensions of round bars. |
| BDS ISO 1035-2 | Hot-rolled steel bars-Part 2: Dimensions of square bars. |
| BDS ISO 1035-3 | Hot-rolled steel bars-Part 3: Dimensions of flat bars. |
| BDS ISO 1035-4 | Hot-rolled steel bars-Part 4: Tolerances. |
| BDS ISO 4951-1 | High yield strength steel bars and sections-Part 1: General
delivery requirements. |
| BDS ISO 4951-2 | High yield strength steel bars and sections-Part 2: Delivery
conditions for normalized, normalized rolled and as-rolled
steels. |
| BDS ISO 4951-3 | High yield strength steel bars and sections-Part 3: Delivery
conditions for thermo mechanically-rolled steels. |
| ASTM A29/A29M | Standard Specification for Steel Bars, Carbon and Alloy, Hot-
Wrought, General Requirements for. |
| ASTM A49 | Standard Specification for Heat-Treated Carbon Steel Joint
Bars, Micro alloyed Joint Bars, and Forged Carbon Steel
Compromise Joint Bars. |
| ASTM A108 | Standard Specification for Steel Bar, Carbon and Alloy, Cold-
Finished. |
| ASTM A116 | Standard Specification for Metallic-Coated, Steel Woven Wire
Fence Fabric. |
| ASTM A185/A185M | Standard Specification for Steel Welded Wire Reinforcement,
Plain, for Concrete. |
| ASTM A227/A227M | Standard Specification for Steel Wire, Cold-Drawn for
Mechanical Springs. |
| ASTM A228/A228M | Standard Specification for Steel Wire, Music Spring Quality. |
| ASTM A229/A229M | Standard Specification for Steel Wire, Oil-Tempered for
Mechanical Springs. |
| ASTM A276 | Standard Specification for Stainless Steel Bars and Shapes. |
| ASTM A311/A311M | Standard Specification for Cold-Drawn, Stress-Relieved
Carbon
Steel
Bars
Subject
to
Mechanical
Property
Requirements. |
| ASTM A322 | Standard Specification for Steel Bars, Alloy, Standard Grades. |
| ASTM A108 | Standard Specification for Steel Bar, Carbon and Alloy, Cold-
Finished. |
| ASTM A368 | Standard Specification for Stainless Steel Wire Strand. |
| ASTM A434 | Standard Specification for Steel Bars, Alloy, Hot-Wrought or
Cold-Finished, Quenched and Tempered. |
| ASTM A475 | Standard Specification for Zinc-Coated Steel Wire Strand. |
| ASTM A478 | Standard Specification for Chromium-Nickel Stainless Steel
Weaving and Knitting Wire. |
| ASTM A479/A479M | Standard Specification for Stainless Steel Bars and Shapes for
Use in Boilers and Other Pressure Vessels. |
| ASTM A492 | Standard Specification for Stainless Steel Rope Wire. |
| ASTM A499 | Standard Specification for Steel Bars and Shapes, Carbon
Rolled from “T” Rails. |
| ASTM A510 | Standard Specification for General Requirements for Wire
Rods and Coarse Round Wire, Carbon Steel. |
| ASTM A575 | Standard Specification for Steel Bars, Carbon, Merchant
Quality, M-Grades. |
| ASTM A576 | Standard Specification for Steel Bars, Carbon, Hot-Wrought,
Special Quality. |
| ASTM A580/A580M | Standard Specification for Stainless Steel Wire. |
| ASTM A586 | Standard Specification for Zinc-Coated Parallel and Helical
Steel Wire Structural Strand. |
| ASTM A603 | Standard Specification for Zinc-Coated Steel Structural Wire
Rope. |
| ASTM A627 | Standard Test Methods for Tool-Resisting Steel Bars, Flats,
and Shapes for Detention and Correctional Facilities. |
| ASTM A663/A663M | Standard Specification for Steel Bars, Carbon, Merchant
Quality, Mechanical Properties. |
| ASTM A666 | Standard Specification for Annealed or Cold-Worked
Austenitic Stainless Steel Sheet, Strip, Plate, and Flat Bar. |
| ASTM A706/A706M | Standard Specification for Low-Alloy Steel Deformed and
Plain Bars for Concrete Reinforcement. |
| ASTM A764 | Standard Specification for Metallic Coated Carbon Steel Wire,
Coated at Size and Drawn to Size for Mechanical Springs. |
| ASTM C933 | Standard Specification for Welded Wire Lath. |
### **2.8.6 Steel Fasteners**
Steel fasteners shall conform to the following Standards:
| Item | Description |
| --------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS 1373 | Slotted countersunk flat head tapping screws. |
| BDS 1374 | Slotted raised counter. |
| BDS 1375 | Fasteners hexagon products widths across flats. |
| BDS 1405 | Bolts, screws, nuts and accessories terminology and
nomenclature. |
| BDS 1406 | Hexagon nuts style 2 products grades A and B. |
| BDS 1407 | Hexagon nuts style 3 products grades A and B. |
| BDS 1408 | General purpose screw threads general plan. |
| BDS 1409 | General purpose screw threads selected sizes for screws, bolts
and nuts. |
| BDS 1410 | Thread run-outs for fasteners thread of BDS 1408: 1995 and
BDS 1409: 1993. |
| BDS 1411 | Tapping screws thread. |
| BDS 1412 | Thread undercuts of external metric thread fasteners. |
| BDS 1413 | Head configuration and gauging of countersunk head screws. |
| BDS 1428 | Fasteners-bolts,
screws,
studs
and
nuts-symbols
and
designations of dimensions. |
| ASTM A31 | Standard Specification for Steel Rivets and Bars for Rivets,
Pressure Vessels. |
| ASTM A183 | Standard Specification for Carbon Steel Track Bolts and Nuts. |
| ASTM A193/A193M | Standard Specification for Alloy-Steel and Stainless Steel
Bolting Materials for High Temperature or High Pressure
Service and Other Special Purpose Applications. |
| ASTM A194/A194M | Standard Specification for Carbon and Alloy Steel Nuts for
Bolts for High Pressure or High Temperature Service, or
Both. |
| ASTM A307 | Standard Specification for Carbon Steel Bolts and Studs,
60000 psi Tensile Strength. |
| ASTM A320/A320M | Standard Specification for Alloy-Steel and Stainless Steel
Bolting Materials for Low-Temperature Service. |
| ASTM A325 | Standard Specification for Structural Bolts, Steel, Heat
Treated, 120/105 ksi Minimum Tensile Strength. |
| ASTM A354 | Standard Specification for Quenched and Tempered Alloy
Steel Bolts, Studs, and Other Externally Threaded Fasteners. |
| ASTM A437/A437M | Standard Specification for Stainless and Alloy-Steel Turbine-
Type Bolting Specially Heat Treated for High-Temperature
Service. |
| ASTM A449 | Standard Specification for Hex Cap Screws, Bolts and Studs, Steel, Heat Treated, 120/105/90 ksi Minimum Tensile
Strength, General Use. |
| ASTM A489 | Standard Specification for Carbon Steel Lifting Eyes. |
| ASTM A490 | Standard Specification for Structural Bolts, Alloy Steel, Heat
Treated, 150 ksi Minimum Tensile Strength. |
| ASTM A502 | Standard Specification for Rivets, Steel, Structural. |
| ASTM A540/A540M | Standard Specification for Alloy-Steel Bolting for Special
Applications. |
| ASTM A563 | Standard Specification for Carbons and Alloy Steel Nuts. |
| ASTM A574 | Standard Specification for Alloy Steel Socket-Head Cap
Screws. |
| ASTM C514 | Standard Specification for Nails for the Application of
Gypsum Board. |
| ASTM C954 | Standard Specification for Steel Drill Screws for the
Application of Gypsum Panel Products or Metal Plaster Bases
to Steel Studs from 0.033 in. (0.84 mm) to 0.112 in. (2.84
mm) in Thickness. |
| ASTM C955 | Standard Specification for Load-Bearing (Transverse and
Axial) Steel Studs, Runners (Tracks), and Bracing or Bridging
for Screw Application of Gypsum Panel Products and Metal
Plaster Bases. |
| ASTM C1002 | Standard Specification for Steel Self-Piercing Tapping Screws
for the Application of Gypsum Panel Products or Metal
Plaster Bases to Wood Studs or Steel Studs. |
| ASTM F436 | Standard Specification for Hardened Steel Washers. |
| ASTM F593 | Standard Specification for Stainless Steel Bolts, Hex Cap
Screws, and Studs. |
| ASTM F594 | Standard Specification for Stainless Steel Nuts. |
| ASTM F844 | Standard Specification for Washers, Steel, Plain (Flat),
Unhardened for General Use. |
| ASTM F959 | Standard Specification for Compressible-Washer-Type Direct
Tension Indicators for Use with Structural Fasteners. |
### **2.8.7 Welding Electrodes and Wires**
Welding electrodes and wires shall conform to the following Standards:
| Item | Description |
| ----------- | --------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS 239 | Specification for soft solder. |
| BDS 1442-1 | Filler rods and wire for gas shielded arc-welding-ferric steel. |
| BDS 1442-2 | Filler rods and wire for gas shielded arc-welding-austenitic
stainless steel. |
| BDS 1442-3 | Filler rods and wires for gas shielded arc welding-copper and
copper alloy. |
| BDS 1442-4 | Filler rods and wires for gas shielded arc welding-aluminum and
aluminum alloy and magnesium alloys. |
| BDS 1442-5 | Filler rods and wires for gas shielded arc welding-nickel and
nickel alloys. |
| IS 814 | Specification for covered electrodes for manual metal arc
welding of carbon and carbon manganese steel. |
| IS 815 | Classification and coding of covered electrodes for metal arc
welding of structural steels. |
| IS 1278 | Specification for filler rods and wires for gas welding. |
| IS 1395 | Specification for low and medium alloy steel covered electrodes
for manual metal arc welding. |
| IS 3613 | Acceptance tests for wire flux combinations for submerged-arc
welding of structural steel. |
| IS 4972 | Specification for resistance spot-welding electrodes. |
| IS 6419 | Specification for welding rods and bare electrodes for gas
shielded arc welding of structural steel. |
| IS 6560 | Specification for molybdenum and chromium-molybdenum low
alloy steel welding rods and bare electrodes for gas shielded arc
welding. |
| IS 7280 | Specification for base wire electrodes for submerged-arc
welding of structural steels. |
| IS 8363 | Specification for bare wire electrodes for electro slag welding of
steels. |
| ISO 9453 | Soft solder alloys-chemical compositions and forms. |
| ISO 9454 | Soft soldering fluxes-classification and requirements. |
| | Part 1: Classification, labeling and packaging. |
| ISO 9455-1 | Soft soldering fluxes- test methods. |
| | Part 1: Determination of non-volatile matter, gravimetric method. |
| ISO 9455-8 | Soft soldering fluxes-test methods. |
| | Part 8: Determination of zinc content. |
| ISO 9455-11 | Soft soldering fluxes-test methods. |
| | Part 11: Solubility of flux residues. |
| ISO 9455-14 | Soft soldering fluxes-test methods. |
| | Part 14: Assessment of tackiness of flux residues. |
## **2.9 Timber & Wood Products**
### **2.9.1 Timber Types and Properties**
Timber types for the structural purpose with their engineering characteristics are contained in Table 6.11.1 Part 6 of this Code. Details of the uses of timber in structures or elements of structures including terminology, material requirements, and moisture content preferred cut sizes of sawn timbers, grading, permissible defects, suitability in respect of durability and treatability, design criteria, and details of joints are also given in Chapter 11 Part 6. Timber and timber constructions shall satisfy the requirements of that Chapter and conform to the following Standards:
| Item | Description |
| -------- | ----------------------------------------------------------------------------------------------------------------- |
| BDS 142 | Specification for wood doors. |
| BDS 173 | Specification for wood windows. |
| BDS 230 | Glossary of terms applicable to timber, plywood and joinery. |
| BDS 803 | Trade names and abbreviated symbols for timber species. |
| BDS 819 | Code of practice for preservation of timber. |
| BDS 820 | Recommendation for maximum permissible moisture content of
timber used for different purposes in Bangladesh. |
| BDS 857 | Specification for grading rules for logs and sawn timbers. |
| BDS 1090 | Methods of test for plywood. |
| BDS 1256 | Classification of commercial timber. |
| BDS 1311 | Key for identification of commercial timber. |
### **2.9.2 Plywood**
A wood structural panel comprised of plies of wood veneer arranged in cross-aligned layers. The plies are bonded with waterproof adhesive that cures on application of heat and pressure.
Plywood shall conform to the following Standards:
* BDS 799 Specification for plywood for general purposes. BDS 1158 Specification for veneered decorative plywood.
For sampling and testing of plywood, the following Standards are applicable:
* BDS 1087 Specification for method of sampling of plywood. BDS 1090 Methods of test of plywood. IS 4990 Specification for plywood for concrete shattering work. IS 5509 Specification for fire retardant plywood. IS 5539 Specification for Preservative Treated Plywood.
### **2.9.3 Particle Boards and Fibre Boards**
A panel primarily composed of cellulosic materials (usually wood), generally in the form of discrete pieces or particles, as distinguished from fibers. The cellulosic material is combined with synthetic resin or other suitable bonding system by a process in which the inter-particle bond is created by the bonding system under heat and pressure.
Fiber boards are fibrous, homogeneous panel made from lingo-cellulosic fibers (usually wood or cane) and having a density of less than 497 kg per cubic meter but more than 160 kg per cubic meter.
These materials shall conform to the following standards:
BDS 619 Specification for particle board (medium density).
| Item | Description |
| ----------------------------------------------------------------------- | ----------------------------------------------------------------- |
| BDS 620 | Specification for hardboard. |
| BDS EN 316 | Wood fiberboards-Definition, classification and symbols. |
| ISO 820 | Particle boards-Definition and classification. |
| ISO 821 | Particle boards-Determination of dimensions of test pieces. |
| ISO 822 | Particle boards-Determination of density. |
| ISO 823 | Particle boards-Determination of moisture content. |
| ISO 766 | Fibre building boards-Determination of dimensions of test pieces. |
| ISO 767 | Fibre building boards-Determination of moisture content. |
| ISO 768 | Fibre building boards-Determination of bending strength. |
| ISO 769 | Fibre building boards-Hard and medium boards-determination of. |
| Water Absorption and of Swelling in Thickness after Immersion in Water; | |
| Item | Description |
| ----------------------------------------------------------------------------- | --------------------------------------------------------- |
| ISO 818 | Fibre building boards-Definition-Classification. |
| ISO 819 | Fibre building boards-Determination of density. |
| ISO 2695 | Fibre building boards-Hard and medium boards for general. |
| Purposes-Quality Specifications-Appearance, Shape and Dimensional Tolerances; | |
* ISO 2696 Fibre building boards-Hard and medium boards-Quality.
Specifications- Water Absorption and Swelling in Thickness;
| Item | Description |
| -------------------- | ------------------------------------------------------------------ |
| ISO 3340 | Fibre building boards-Determination of sand content. |
| ISO 3346 | Fibre building boards-Determination of surface finish (roughness). |
| ISO 3729 | Fibre building boards-Determination of surface stability. |
| ISO/TR 7469 | Dimensional stability of hardboards. |
| Wood based Laminates | |
Laminated boards having a core of strips, each not exceeding 7 mm in thickness, glued together face to face to form a slab which in turn is glued between two or more veneers, with the direction of the grain of the core strips running at right angles to that of the adjacent outer veneers.
Wood based laminates shall conform to the following Standards:
IS 3513 Specification for resin treated compressed wood laminates (compregs). Part 3 For general purposes. IS 3513 Specification for resin treated compressed wood laminates (compregs). Part 4 Sampling and Tests.
IS 9307 Methods of tests for wood-based structural sandwich construction. (Parts I to VIII) Part I Flexure test. Part II Edgewise compression test. Part III Flatwise compression test. Part IV Shear test. Part V Flatwise tension test. Part VI Flexure creep test. Part VII Cantilever vibration test. Part VIII Weathering test.
### **2.9.4 Adhesives and Glues**
Adhesives and glues are used to join two or more parts so as to form a single unit. Adhesives shall conform to the following Standards:
IS 848 Specification for synthetic resign adhesives for plywood (phenolic and aminoplastic). IS 849 Specification for cold setting case in glue for wood. IS 851 Specification for synthetic resin adhesives for construction work (nonstructural) in wood.
| Item | Description |
| ------- | ----------------------------------------------------------------------------------------------------------------- |
| IS 852 | Specification for animal glue for general wood-working purposes. |
| IS 4835 | Specification for polyvinyl acetate dispersion-based adhesives for
wood. |
| IS 9188 | Specification for adhesive for structural laminated wood products for
use under exterior exposure condition. |
## **2.10 Doors, Windows and Ventilators**
### **2.10.1 Wooden Doors, Windows and Ventilators**
These shall conform to the following Standards:
| Item | Description |
| -------- | ----------------------------------------------------------------------------------------------------------------- |
| BDS 142 | Specification for wood door. |
| BDS 173 | Specification for wood windows. |
| BDS 820 | Recommendation for maximum permissible moisture content of
timber used for different purposes in Bangladesh. |
| BDS 1504 | Timber door window and ventilator frames |
| IS 1003 | Specification for timber panelled and glazed shutters. |
| | Part 1- 2003 Door shutters. |
| | Part 2- 1994 Window and ventilator shutters. |
| IS 1826 | Specification for venetian blinds for windows. |
| IS 2191 | Specification for wooden flush door shutters (cellular and hollow
core type). |
| | Part 1 Plywood face panels. |
| | Part 2 Particle board face panels and hardboard face panels. |
| IS 2202 | Specification for wooden flush door shutters (solid core type). |
| | Part 1 Plywood face panels. |
| | Part 2 Particle board face panels and hardboard face panels. |
| IS 4020 | Method of tests for door shutters. |
| | (Part 1): 1998 General. |
| | (Part 2): 1998 Measurement of dimensions and squareness. |
| | (Part 3): 1998 Measurement of general flatness. |
| | (Part 4): 1998 Local planeness test. |
| | (Part 5): 1998 Impact indentation test. |
| | (Part 6): 1998 Flexure test. |
| | (Part 7): 1998 Edge loading test. |
| | (Part 8): 1998 Shock resistance test. |
| | (Part 9): 1998 Buckling resistance test. |
| | (Part 10):1998 Slamming test. |
| | (Part 11):1998 Misuse test. |
| | (Part 12):1998 Varying humidity test. |
| | (Part 13):1998 End immersion test. |
| | (Part 14):1998 Knife test. |
| | (Part 15):1998 Glue adhesion test. |
| | (Part 16):1998 Screw withdrawal resistance test. |
| IS 4021 | Specification for timber door, window and ventilator frames. |
| IS 4962 | Specification for wooden side sliding doors. |
| IS 6198 | Specification for ledged, braced and battened timber shutters. |
### **2.10.2 Metal Doors, Windows Frames and Ventilators**
These shall conform to the following Standards:
| Item | Description |
| -------- | ------------------------------------------------------------------------------------ |
| BDS 1270 | Specification for strong room door |
| BDS 1273 | Specification for vault doors. |
| IS 1038 | Specification for steel doors, windows and ventilators. |
| IS 1361 | Specification for steel windows for industrial buildings. |
| IS 1948 | Specification for aluminum doors, windows and ventilators. |
| IS 1949 | Specification for aluminum windows for industrial buildings. |
| IS 4351 | Specification for steel door frames. |
| IS 6248 | Specification for metal rolling shutters and rolling grills. |
| IS 7452 | Specification for hot rolled steel sections for doors, windows and
ventilators. |
| IS 10451 | Specification for steel sliding shutters (top hung type). |
| IS 10521 | Specification for collapsible gates. |
### **2.10.3 Plastic Doors and Windows**
These shall conform to the following Standards:
|BDS EN 477|Unplasticized polyvinylchloride (PVC-U) profiles for the
fabrication of windows and doors-Determination of the
resistance to impact of main profiles by falling mass.|
|BDS EN 478|Unplasticized polyvinylchloride (PVC-U) profiles for the
fabrication of windows and doors-Determination of appearance
after exposure at $150^\circ\text{C}$.|
|BDS EN 479|Unplasticized polyvinylchloride (PVC-U) profiles for the
fabrication of windows and doors-Determination of heat
reversion.|
|BDS EN 513|Unplasticized polyvinylchloride (PVC-U) profiles for the
fabrication of windows and doors-Determination of the
resistance to artificial weathering.|
|BDS EN 514|Unplasticized polyvinylchloride (PVC-U) profiles for the
fabrication of windows and doors-Determination of the strength
of welded corners and T-joints.|
|BDS EN 12608|Unplasticized polyvinylchloride (PVC-U) profiles for the
fabrication of windows and doors-Classification, requirements
and test methods.|
|BDS ISO 1163-1|Plastics-Unplasticized polyvinylchloride (PVC-U) molding and
extrusion materials-Part 1: Designation system and basis for
specifications.|
|BDS ISO 1163-2|Plastics-Unplasticized polyvinylchloride (PVC-U) molding and
extrusion materials-Part 2: Preparation of test specimens and
determination of properties.|
|IS 14856|Specification for glass fibre reinforced (GRP) panel type door
shutters for internal use.|
|IS 15380|Specification for molded raised high density fibre (HDF) panel
doors.|
## **2.11 Aluminium and Aluminium Alloys**
Aluminum used for structural purposes in buildings and structures shall comply with AA ASM 35 and AA ADM 1.
Aluminium and Aluminium Alloys shall also conform to the following Standards:
| Item | Description |
| --------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS EN 755-9 | Aluminum and aluminum alloys-Extruded rod/bar, tube and
profiles-Part 9: Profiles, tolerances on dimensions and form. |
| BDS EN 755-2 | Aluminum and aluminum alloys-Extruded rod/bar, tube and
profiles-Part 2: Mechanical properties. |
| BDS EN 755-1 | Aluminum and aluminum alloys-Extruded rod/bar, tube and
profiles-Part 1: Technical conditions for inspection and
delivery. |
| BDS EN 755-3 | Aluminum and aluminum alloys-Extruded rod/bar, tube and
profiles-Part 3: Round bars, tolerances on dimensions and
form. |
| BDS EN 755-4 | Aluminum and aluminum alloys-Extruded rod/bar, tube and
profiles-Part 4: Square bars, tolerances on dimensions and
form. |
| BDS EN 755-5 | Aluminum and aluminum alloys-Extruded rod/bar, tube and
profiles-Part 5: Rectangular bars, tolerances on dimensions and
form. |
| BDS EN 755-6 | Aluminum and aluminum alloys-Extruded rod/bar, tube and
profiles-Part 6: Hexagonal bars, tolerances on dimensions and
form. |
| BDS EN 755-7 | Aluminum and aluminum alloys-Extruded rod/bar, tube and
profiles-Part 7: Seamless tubes, tolerances on dimensions and
form. |
| BDS EN 755-8 | Aluminum and aluminum alloys-Extruded rod/bar, tube and
profiles-Part 8: Porthole tubes, tolerances on dimensions and
form. |
| BDS EN 12020-1 | Aluminum and aluminum alloys-Extruded precision profiles in
alloys EN AW-6060 and EN AW-6063- Part 1: Technical
conditions for inspection and delivery. |
| BDS EN 12020-2 | Aluminum and aluminum alloys-Extruded precision profiles in
alloys EN AW-6060 and EN AW-6063-Part 2: Tolerances on
dimensions and form. |
| BDS EN 515 | Aluminum and aluminum alloys-Wrought products-Temper
designations. |
| ASTM B26/B26M | Standard Specification for Aluminum-Alloy Sand Castings. |
| ASTM B85/B85M | Standard Specification for Aluminum-Alloy Die Castings. |
| ASTM B108/B108M | Standard Specification for Aluminum-Alloy Permanent Mold
Castings. |
| ASTM B209 | Standard Specification for Aluminum and Aluminum-Alloy
Sheet and Plate. |
| ASTM B210 | Standard Specification for Aluminum and Aluminum-Alloy
Drawn Seamless Tubes. |
| ASTM B211 | Standard Specification for Aluminum and Aluminum-Alloy
Bar, Rod, and Wire. |
| ASTM B221 | Standard Specification for Aluminum and Aluminum-Alloy
Extruded Bars, Rods, Wire, Profiles, and Tubes. |
| ASTM B241/B241M | Standard Specification for Aluminum and Aluminum-Alloy
Seamless Pipe and Seamless Extruded Tube. |
| ASTM B308/B308M | Standard Specification for Aluminum-Alloy 6061-T6 Standard
Structural Profiles. |
| ASTM B313/B313M | Standard Specification for Aluminum and Aluminum-Alloy
Round Welded Tubes. |
| ASTM B316/B316M | Standard Specification for Aluminum and Aluminum-Alloy
Rivet and Cold-Heading Wire and Rods. |
| ASTM B429/B429M | Standard
Specification
for
Aluminum-Alloy
Extruded
Structural Pipe and Tube. |
| ASTM B483/B483M | Standard Specification for Aluminum and Aluminum-Alloy
Drawn Tube and Pipe for General Purpose Applications. |
| ASTM B547/B547M | Standard Specification for Aluminum and Aluminum-Alloy
Formed and Arc-Welded Round Tube. |
| ASTM B632/B632M | Standard Specification for Aluminum-Alloy Rolled Tread
Plate. |
| ASTM B745/B745M | Standard Specification for Corrugated Aluminum Pipe for
Sewers and Drains. |
| ASTM E34 | Standard Test Methods for Chemical Analysis of Aluminum
and Aluminum-Base Alloys. |
## **2.12 Builders Hardware**
The applicable Standards are listed below:
* BDS 113 Specification for latches and locks for doors in buildings. IS 204 Specification for tower bolts. Part 1 Ferrous metals. Part 2 Nonferrous metals.
* IS 205 Specification for nonferrous metal butt hinges. IS 206 Specification for tee and strap hinges. IS 208 Specification for door handles. IS 281 Specification for mild steel sliding door bolts for use with padlock. IS 362 Specification for parliament hinges. IS 363 Specification for hasps and staples. IS 364 Specification for fanlight catch. IS 452 Specification for door springs, rat-tail type. IS 453 Specification for double acting spring hinges. IS 729 Specification for drawer locks, cupboard locks and box locks. IS 1019 Specification for rim latches. IS 1341 Specification for steel butt hinges.
| Item | Description |
| -------- | --------------------------------------------------------------------------------------------------- |
| IS 1823 | Specification for floor door stoppers. |
| IS 1837 | Specification for fanlight pivots. |
| IS 2209 | Specification for mortise locks (vertical type). |
| IS 2681 | Specification for nonferrous metal sliding door bolts for use with
padlocks. |
| IS 3564 | Specification for door closers (hydraulically regulated). |
| IS 3818 | Specification for continuous (piano) hinges. |
| IS 3828 | Specification for ventilator chains. |
| IS 3843 | Specification for steel back-flap hinges. |
| IS 3847 | Specification for mortise night latches. |
| IS 4621 | Specification for indicating bolts for use in public baths and lavatories. |
| IS 4948 | Specification for welded steel wire fabric for general use. |
| IS 4992 | Specification for door handles for mortise locks (vertical type). |
| IS 5187 | Specification for flush bolts. |
| IS 5899 | Specification for bathroom latches. |
| IS 5930 | Specification for mortise latch (vertical type). |
| IS 6315 | Specification for floor springs (hydraulically regulated) for heavy doors. |
| IS 6318 | Specification for plastic window stays and fasteners. |
| IS 6343 | Specification for door closers (pneumatically regulated) for light doors
weighing up to 40 kg. |
| IS 6602 | Specification for ventilator poles. |
| IS 6607 | Specification for rebated mortise locks (vertical type). |
| IS 7196 | Specification for hold fast. |
| IS 7197 | Specification for double action floor springs (without oil check) for heavy
doors. |
| IS 7534 | Specification for sliding locking bolts for use with padlocks. |
| IS 7540 | Specification for mortise dead locks. |
| IS 8756 | Specification for ball catches for use in wooden almirah. |
| IS 8760 | Specification for mortise sliding door locks, with lever mechanism. |
| IS 9106 | Specification for rising butt hinges. |
| IS 9131 | Specification for rim locks. |
| IS 9460 | Specification flush drop handle for drawer. |
| IS 9899 | Specification for hat, coat and wardrobe hooks. |
| IS 10019 | Specification for steel window stays and fasteners. |
| IS 10090 | Specification for numerical. |
| IS 10342 | Specification for curtain rail system. |
| IS 12817 | Specification for stainless steel butt hinges. |
| IS 12867 | Specification for PVC hand rails covers. |
| IS 14912 | Specification for door closers concealed type (hydraulically regulated) |
## **2.13 Roof Coverings**
### **2.13.1 Scope**
The provisions of this Section shall govern the materials used for roof coverings.
### **2.13.2 Compatibility of Materials**
All roofs and roof coverings shall be of materials that are compatible with each other and with the building or structure to which the materials are applied.
### **2.13.3 Material Specifications and Physical Characteristics**
All materials to be used in the construction of roofs and roof coverings shall conform to the applicable standards listed in this Section. In the absence of applicable standards or when materials are of questionable suitability, testing by an approved testing agency may be required by the building official to determine the character, quality and limitations of use of the materials.
### **2.13.4 Weather Protection**
All roofs shall be covered with approved roof coverings properly secured to the building or structure to resist wind and rain. Roof coverings shall be designed, installed and maintained in accordance with approved manufacturer's recommendations such that the roof covering shall serve to protect the building or structure.
### **2.13.5 Wind Resistance**
All roofs and roof coverings shall be secured in place to the building or structure to withstand the wind loads.
### **2.13.6 Structural and Construction Loads**
The structural roof components shall be capable of supporting the roof covering system and the material and equipment loads that will be encountered during installation of the roof covering system.
### **2.13.7 Impact Resistance**
Roof coverings shall resist impact damage based on the results of tests conducted in accordance with ASTM D4272 or ASTM D3746.
### **2.13.8 Metal-Sheet Roof Coverings**
Metal-sheet roof coverings installed over structural framing and decking shall comply with BDS 868, Galvanized corrugated sheet roof and wall coverings; BDS 1122, Hot-dip galvanized steel sheet and coil; ASTM A755/A755M or ASTM B101. Metal-sheet roof coverings shall be installed in accordance with approved manufacturer's installation instructions.
### **2.13.9 Interlocking Clay or Cement Tile**
Interlocking clay or cement tile shall be installed only over solid sheathing or spaced structural sheathing boards. Interlocking clay or cement tile shall not be installed on roof slopes below one unit vertical in three units horizontal (1:3). Horizontal battens shall be required on roof slopes over one unit vertical in two units horizontal (1:2). Single layer underlayment is required over solid sheathing on all roof slopes. Reinforced underlayment shall be required when spaced sheathing is used. Regardless of roof slope, the first three tile courses and all tiles within 900 mm of roof edges, tiles at changes in roof slope or changes in slope direction, shall be fastened to the roof. For the field of the roof, fastening is not required on roof slopes below one unit vertical in two units horizontal (1:2). Every other tile course shall be fastened on roof slopes 1:2 to less than
1:1; and every tile shall be fastened on roof slopes 1:1 and over. Tile overlap shall be in accordance with approved manufacturer's installation instructions.
### **2.13.10 Non-interlocking Clay or Cement Tile**
Non-interlocking clay or cement tile shall not be installed on roof slopes below one unit vertical in five units horizontal (1:5). Double layer underlayment is required on roof slopes below one unit vertical in four units horizontal (1:4). Single layer underlayment is required on all other roof slopes. Non-interlocking clay or cement tile shall be secured to the roof with two fasteners per tile. The minimum tile overlap shall be 75 mm.
### **2.13.11 Roof Insulation**
Rigid combustible roof insulation shall be permitted, provided the insulation is covered with approved roof coverings directly applied thereto. In-situ lime concrete may be used on flat roofs of buildings. Minimum compacted thickness of such a layer shall be 75 mm and have adequate slope for drainage. The materials used in lime concrete shall conform to the standards specified in Sec 2.5 of this Part.
### **2.13.12 Recovering and Replacement of Roof Coverings**
New roof coverings shall not be installed without first removing existing roof coverings when the existing roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering is not acceptable as a base for additional roofing.
### **2.13.13 Reuse of Materials**
Existing slate, clay or cement tile shall be permitted for reuse, except that damaged, cracked or broken slate or tile shall not be reused. Existing vent flashings, metal edgings, drain outlets, collars and metal counter flashings shall not be reused where rusted, damaged or deteriorated. Aggregate surfacing materials shall not be reused.
### **2.13.14 Applicable Standards**
The applicable Standards for materials used in roofs and roof coverings are listed below:
| Item | Description |
| --------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS 868 | Code of practice for galvanized corrugated sheet roof and wall
coverings. |
| BDS 1122 | Specification for hot-dip galvanized steel and coil. |
| BDS EN 490 | Concrete roofing tiles and fittings for roof covering and all
cladding-Product specifications. |
| BDS EN 491 | Concrete roofing tiles and fittings for roof covering and wall
cladding-Test methods. |
| BDS EN 538 | Clay roofing tiles for discontinuous laying-Flexural strength
test. |
| BDS EN 539-l | Clay roofing tiles for discontinuous laying Determination of
physical characteristics-Part 1: Impermeability test. |
| BDS EN 1024 | Clay roofing tiles for discontinuous laying-Determination of
geometric characteristics. |
| BDS EN 1304 | Clay roofing tiles and fittings-Product definitions and
specifications. |
| ASTM A755/A755M | Standard Specification for Steel Sheet, Metallic Coated by the Hot-Dip Process and Pre-painted by the Coil-Coating Process
for Exterior Exposed Building Products. |
| ASTM B101 | Standard Specification for Lead-Coated Copper Sheet and Strip
for Building Construction. |
| ASTM C406 | Standard Specification for Roofing Slate. |
| ASTM C836/C836M | Standard Specification for High Solids Content, Cold Liquid-Applied Elastomeric Waterproofing Membrane for Use with
Separate Wearing Course. |
| ASTM C1029 | Standard Specification for Spray-Applied Rigid Cellular
Polyurethane Thermal Insulation. |
| ASTM D225 | Standard Specification for Asphalt Shingles (Organic Felt)
Surfaced With Mineral Granules. |
| ASTM
D226/D226M | Standard Specification for Asphalt-Saturated Organic Felt Used
in Roofing and Waterproofing. |
| ASTM D227 | Standard Specification for Coal-Tar-Saturated Organic Felt
Used in Roofing and Waterproofing. |
| ASTM D312 | Standard Specification for Asphalt Used in Roofing. |
| ASTM D450 | Standard Specification for Coal-Tar Pitch Used in Roofing,
Damp proofing, and Waterproofing. |
| ASTM D1227 | Standard Specification for Emulsified Asphalt Used as a
Protective Coating for Roofing. |
| ASTM D1863 | Standard Specification for Mineral Aggregate Used on Built-Up Roofs. |
| ASTM D2178 | Standard Specification for Asphalt Glass Felt Used in Roofing
and Waterproofing. |
| ASTM D2626 | Standard Specification for Asphalt-Saturated and Coated
Organic Felt Base Sheet Used in Roofing. |
| ASTM D2898 | Standard Practice for Accelerated Weathering of Fire-Retardant-
Treated Wood for Fire Testing. |
| ASTM D3161 | Standard Test Method for Wind-Resistance of Asphalt Shingles
(Fan-Induced Method). |
| ASTM D3747 | Standard Specification for Emulsified Asphalt Adhesive for
Adhering Roof Insulation. |
| ASTM D3909 | Standard Specification for Asphalt Roll Roofing (Glass Felt)
Surfaced With Mineral Granules. |
| ASTM D4272 | Standard Test Method for Total Energy Impact of Plastic Films
By Dart Drop. |
| ASTM
D4434/D4434M | Standard Specification for Poly (Vinyl Chloride) Sheet Roofing. |
| ASTM D4601 | Standard Specification for Asphalt-Coated Glass Fiber Base
Sheet Used in Roofing. |
| ASTM D4637 | Standard Specification for EPDM Sheet Used In Single-Ply
Roof Membrane. |
| ASTM
D4897/D4897M | Standard Specification for Asphalt-Coated Glass-Fiber Venting
Base Sheet Used in Roofing. |
| ASTM D6380 | Standard Specification for Asphalt Roll Roofing (Organic Felt). |
| ASTM E108 | Standard Test Methods for Fire Tests of Roof Coverings. |
| ASTM G90 | Standard
Practice
for
Performing
Accelerated
Outdoor
Weathering of Nonmetallic Materials Using Concentrated
Natural Sunlight. |
| ASTM G154 | Standard Practice for Operating Fluorescent Light Apparatus for
UV Exposure of Nonmetallic Materials. |
| ASTM G155 | Standard Practice for Operating Xenon Arc Light Apparatus for
Exposure of Non-Metallic Materials. |
| CGSB (Canadian General Standards
Board) 37-GP-56M-80 | Membrane, modified bituminous, prefabricated, and reinforced
for roofing. |
| FM 447-86 | Approval standard for class I roof coverings. |
| FM ( Factory Manual) 4450-89 | Standard laboratories department approved standard for class I insulated steel deck roofs. |
| RMA (Rubber Manufacturer
Association, USA) RP-4-88 | Wind design guide for ballasted single-ply roofing systems. |
| SPRI (Single Ply Roofing Institute,
USA) -86 | Wind design guide for ballasted single-ply roofing systems. |
## **2.14 Paints and Varnishes**
### **2.14.1 Water Based Paints and Pigments**
Water based paints shall conform to the following Standards:
BDS 500 Specification for distemper dry. BDS 1097 Specification for plastic emulsion paint. Part 1 for Interior use. Part 2 for Exterior use. IS 427 Specification for distemper, dry, color as required. IS 428 Specification for distemper, washable. IS 5410 Specification for cement paint, color as required. IS 5411 Specification for plastic emulsion paint. Part 1: For interior use. Part 2: For exterior use
### **2.14.2 Ready Mixed Paints, Enamels and Powder Coatings**
Ready mixed paints and enamels shall conform to the following Standards:
| Item | Description |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS 13 | Specification for ready mixed paints, varnish, lacquers and related
products. |
| BDS 14 | Specification for black bituminous paint, brushing for general purposes. |
| BDS 397 | Specification for ready mixed paint, brushing, red oxide zinc chrome,
priming. |
| BDS 398 | Specification for ready mixed paint, spraying, red oxide zinc chrome,
priming. |
| BDS 399 | Specification for aluminum paint, spraying for general purposes, in dual
container. |
| BDS 400 | Specification for aluminum paint, brushing, for general purposes in dual
container. |
| BDS 401 | Specification for varnish, finishing, exterior, type-I, (synthetic). |
| BDS 402 | Specification for ready mixed paint, brushing, finishing, semi-gloss, for
general purposes. |
| BDS 499 | Specification for ready mixed paints, brushing, for road marking (white,
yellow and black). |
| BDS 616 | Specification for enamel, brushing, exterior (i) undercoating, (ii)
finishing, color as required. |
| BDS 617 | Specification for enamel, brushing, interior (i) undercoating, (ii)
finishing, color as required. |
| BDS 926 | Specification for ready mixed paint, brushing, petrol resisting, air
drying, for exterior painting of containers, color as required. |
| BDS 927 | Specification for ready mixed paint, brushing, petrol resisting, air
drying, for interior painting of tanks and containers, red oxide (color
unspecified). |
| BDS 928 | Specification for ready mixed paint, brushing, acid resisting, for
protection against acid fumes, color as required. |
| BDS 973 | Specification for specification and methods of test for linseed stand oil
for paints and varnishes. |
| BDS 974 Specification and methods of test for raw tung oils for paints and varnishes. BDS 1005 Specification for ready mixed paint, brushing, finishing, stoving, enamel, color as required. BDS 1141 Specification for ready mixed aluminum priming paints for woodwork. BDS 1151 Specification for pavement marking paints. IS 101 Methods of sampling and test for paints, varnishes and related products: (Part l/Sec 1): Test on liquid paints (general and physical), Section 1 Sampling. (Part l/Sec 2): Test on liquid paints (general and physical), Section 2 Preliminary examination and preparation of samples for testing. (Part l/Sec 3): Test on liquid paints (general and physical), Section 3 Preparation of panels. (Part l/Sec 4): Test on liquid paints (general and physical), Section 4 Brushing test. (Part l/Sec 5): Test on liquid paints (general and physical), Section 5 Consistency. (Part l/Sec 6): Test on liquid paints (general and physical), Section 6 Flash point. (Part l/Sec 7): Test on liquid paints (general and physical), Section 7 Mass per 10 Iitres. (Part 2/Sec 1): Test on liquid paints (chemical examination), Section 1 Water content. (Part 2/Sec 2): Test on liquid paints (chemical examination), Section 2 Volatile matter. (Part 3/Sec 1): Tests on paint film formation, Section 1 Drying time. (Part 3/Sec 2): Tests on paint film formation, Section 2 Film thickness. (Part 3/Sec 4): Tests on paint film formation, Section 4 Finish. (Part 3/Sec 5): Tests on paint film formation, Section 5 Fineness of | |
grind (Part 4/Sec 1): Optical test, Section 1 Opacity. (Part 4/Sec 2): Optical test, Section 2 Color. (Part 4/Sec 3): Optical test, Section 3 Light fastness test. (Part 4/Sec 4): Optical test, Section 4 Gloss. (Part 5/Sec 1): Mechanical test on paint films, Section 1 Hardness tests. (Part 5/Sec 2): Mechanical test on paint films, Section 2 Flexibility and adhesion.
(Part 5/Sec 3): Mechanical test on paint films, Section 3 Impact resistance.
(Part 5/Sec 4): Mechanical test on paint films, Section”4 Print free test.
(Part 6/Sec 1): Durability tests, Section 1 Resistance to humidity under conditions of condensation.
(Part 6/Sec 2): Durability tests, Section 2 Keeping properties.
(Part 6/Sec 3): Durability tests, Section 3 Moisture vapour permeability.
(Part 6/Sec 4): Durability tests, Section 4 Degradation of coatings (pictorial aids for evaluation).
(Part 6/Sec 5): Durability tests, Section 5 Accelerated weathering test.
(Part 7/Sec 1): Environmental tests on paint films, Section 1 Resistance to water. (Part 7/Sec 2): Environmental tests on paint films, Section 2 Resistance to liquids. (Part 7/Sec 3): Environmental tests on paint films, Section 3 Resistance to heat. (Part 7/Sec 4): Environmental tests on paint films, Section 4 Resistance to bleeding of pigments. (Part 8/Sec 1): Tests for pigments and other solids, Section 1 Residue on sieve.
(Part 8/Sec 2): Tests for pigments and other solids, Section 2 Pigments and nonvolatile matter. (Part 8/Sec 3): Tests for pigments and other solids, Section 3 Ash content. (Part 8/Sec 4): Tests for pigments and other solids, Section 4 Phthalic anhydride. (Part 8/Sec 5): Tests for pigments and other solids, Section 5 Lead restriction test. (Part 8/Sec 6): Tests for pigments and other solids, Section 6 Volume solids.
* (Part 9/Sec 1): Tests for lacquers and varnish, Section 1 Acid value. (Part 9/Sec 2): Tests for lacquers and varnish, Section 2 Rosin test.
* IS 104 Specification for ready mixed paint, brushing, zinc chrome, priming. IS 109 Specification for ready mixed paint, brushing, priming, plaster to Indian Standard colors No. 361 and 631.
* IS 123 Specification for ready mixed paint, brushing, finishing, semi-gloss, for general purposes, to Indian Standard colors No. 445, 446, 448, 449, 451 and 473; and red oxide (color unspecified).
* IS 133 Specification for enamel, interior (a) undercoating, (b) finishing. IS 137 Specification for ready mixed paint, brushing, matt or egg-shell flat, finishing, interior, to Indian Standard color, as required.
* IS 158 Specification for ready mixed paint, brushing, bituminous, black, leadfree, acid, alkali, and heat resisting.
* IS 168 Specification for ready mixed paint, air-drying semi-glossy/matt, for general purposes.
* IS 341 Specification for black Japan, Types A, B and C. IS 2074 Specification for ready mixed paint, air drying red oxide-zinc chrome, priming.
* IS 2075 Specification for ready mixed paint, stoving, red oxide-zinc chrome, priming.
| Item | Description |
| -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| IS 2339 | Specification for aluminum paint for general purposes, in dual
container. |
| IS 2932 | Specification for enamel, synthetic, exterior, (a) undercoating, (b)
finishing. |
| IS 2933 | Specification for enamel, exterior, (a) undercoating, (b) finishing. |
| IS 3536 | Specification for ready mixed ‘paint, brushing, wood primer. |
| IS 3537 | Specification for ready mixed paint, finishing, interior for general
purposes, to Indian Standard colors No. 101, 216, 217, 219, 275, 281,
352, 353, 358 to 361, 363, 364, 388, 410, 442, 444, 628, 631, 632, 634,
693, 697, white and black. |
| IS 3539 | Specification for ready mixed paint, undercoating, for use under oil
finishes, to Indian Standard colors, as required. |
| IS 3585 | Specification for ready mixed paint, aluminum, brushing, priming,
water resistant, for wood work. |
| IS 3678 | Specification for ready mixed paint, thick white, for lettering. |
| IS 8662 | Specification for enamel, synthetic, exterior, (a) undercoating,
(b) finishing, for railway coaches. |
| IS 9862 | Specification for ready mixed paint, brushing, bituminous black lead
free, acid, alkali, water and chlorine resisting. |
| IS 11883 | Specification for ready mixed paint, brushing, red oxide, priming for
metals. |
| IS 13183 | Specification for aluminum paints, heat resistant. |
| IS 13213 | Specification for polyurethane full gloss enamel (two pack). |
| IS 13607 | Specification for ready mixed paint, finishing, general purposes,
synthetic. |
| IS 13871 | Specification for powder coatings. |
### **2.14.3 Thinners and Solvents**
These shall conform to the following Standards:
IS 324 Specification for ordinary denatured spirit. IS 82 Methods of sampling and test for thinners and solvents for paints.
| Item | Description |
| -------- | ----------------------------------------------------------------------------------- |
| IS 324 | Specification for ordinary denatured spirit. |
| IS 533 | Specification for gum spirit of turpentine (oil of turpentine). |
| IS 14314 | Specification for thinner general purposes for synthetic paints and
varnishes. |
### **2.14.4 Varnishes and Lacquers**
These materials shall conform to the following Standards:
* BDS 401 Specification for varnish, finishing, exterior, type-I, (synthetic). BDS 1064 Specification for varnish, stoving. BDS 1065 Specification for varnish, acid resisting. BDS 1066 Specification for varnish, finishing, interior. IS 337 Specification for varnish, finishing, interior. IS 347 Specification for varnish, shellac for general purposes. IS 348 Specification for french polish. IS 524 Specification for varnish, finishing, exterior, synthetic. IS 525 Specification for varnish, finishing, exterior and general purposes. IS 642 Specification for varnish medium for aluminum paint.
## **2.15 Sanitary Appliances and Water Fittings**
### **2.15.1 Sanitary Appliances**
Sanitary appliances shall conform to the following Standards:
* ASHRAE 90A Energy conservation in new building design. ASHRAE 90B Energy Conservation in New Building Design. AWWA C700 Cold-Water Meters-Displacement type, bronze main case. AWWA C701 Cold-Water Meters-Turbine type, for customer service. AWWA C702 Cold-Water Meters-Compound type. BDS 1162 Ceramic wash basin and pedestal, ceramic wash basin and pedestals dimension, design & construction, type, permissible deviation
| Item | Description |
| -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| BDS 1163 | Specification for Vitreous Sanitary Appliances,
Part-1, General requirements. |
| | Part-2, Specific requirements for water closets;
Part-3, Specification requirements for urinal (bowl type).
Part-4, Specific requirements for foot rest. |
| | Part-5, Specific requirements for integrated squatting pans. |
| BDS 1361 | Faucets. |
| BDS 1593 | Plastic sanitary squatting pan. |
| BS 1125 | Specification for WC flushing cisterns (including dual flash
cisterns and flush pipes). |
| BS 1244 | Metal Sink for domestic purposes. |
| BS 1254 | Specification for C seats (plastics). |
| BS 1329 | Specification for metal hand rinse basins. |
| BS 1876 | Specification for automatic flushing cistern for urinals. |
### **2.15.2 Pipes and Pipe Fittings for Water Supply and Sanitation**
Pipes and pipe fittings for water supply and sanitation shall comply with the following Standards:
|BDS 1111|Centrifugally cast (spun) iron pressure pipes for water, gas and
sewage.|
|BDS 1356|Specification for ferrules for water services.|
|BDS 1357|Specification for washers with fittings for water service.|
|BDS 1361|Faucets.|
||This standard specifies the technical requirements of various
types of Faucets.|
|BDS 1562|Solvent cements for polyvinylchloride (PVC) plastic pipe and
fitting.|
|BDS 1593|Plastic sanitary squatting pan.
Pan lays down the requirement for material, dimension physical
requirements and testing for power flush type injection molded
high density polyethylene (HDPE) or polypropylene (PP)
squatting pan.|
|BDS EN 1254‐2|Copper and copper alloys ‐ Plumbing fittings-Part 2: Fittings with
compression ends for use with copper tubes.|
|BDS EN 1717|Protection against pollution of potable water in water installations
and general requirements of devices to prevent pollution by
backflow.|
|BDS EN 14506|Devices to prevent pollution by backflow of potable water-
Automatic diverter-Family H, type C.|
|BDS ISO 3419|Non-alloy and alloy steel butt-welding fittings.|
|BDS ISO 5251|Stainless steel butt-welding fittings.|
|BDS ISO 6761|Steel tubes-Preparation of ends of tubes and fittings for welding.|
|BDS ISO 3822-1|Acoustics: Laboratory tests on noise emission from appliances
and equipment used in water supply installations-Part 1: Method
of measurement.|
|BDS ISO 3822 ‐2|Acoustics: Laboratory tests on noise emission from appliances
and equipment used in water supply installations-Part 2:
Mounting and operating conditions for draw‐off taps and mixing
valves.|
|BDS ISO 3822 ‐4|Acoustics: Laboratory tests on noise emission from appliances
and equipment used in water supply installations-Part 4:
Mounting and operating conditions for special appliances.|
|BDS ISO 161-1|Thermoplastics pipes for the conveyance of fluids Nominal
outside diameters and Nominal Pressures- Part 1: Metric series.|
|BDS ISO 161-2|Thermoplastics pipes for the conveyance of fluids- Nominal
outside diameters and Nominal Pressures- Part 2: Inch-based
series.|
|BDS ISO 265-1|Pipes and fittings of plastics materials- fittings for domestic and
industrial waste pipes- Basic dimensions: Metric series- Part 1:
Un-plasticized Poly (Vinyl chloride) (PVC-U).|
|BDS ISO 1167-1|Thermoplastics pipes fittings and assemblies for the conveyance
of fluids-Determination of the resistance to internal pressure- Part
1: General method.|
|BDS ISO 1167-2|Thermoplastics pipes fittings and assemblies for the conveyance
of fluids- Determination of the resistance to internal pressure-
Part 2: Preparation of pipe test pieces.|
|BDS ISO 1746|Rubber or Plastics hoses and tubing-bending tests.|
|BDS ISO 2505|Thermoplastics pipes- Longitudinal reversion-Test method and
parameters.|
|BDS ISO 2507-2|Thermoplastics pipes and fittings-Vista softening temperature-
Part 2: Test conditions for Un-plasticized polyvinylchloride
(PVC-U) or chlorinated polyvinylchloride (PVC-C) pipes and
fittings and for high impact resistance polyvinylchloride (PVC-
HI) pipes.|
|BDS ISO 3114|Unplasticized polyvinylchloride (PVC) pipes for potable water
supply-Extractability of lead and tin- Test method.|
|BDS ISO 3126|Plastics piping systems-Plastics components- Determination of
dimensions.|
|BDS ISO 3127|Thermoplastics pipes-Determination of resistance to external
blows-round-the-clock method.|
|BDS ISO 3501|Assembled joints between fittings and polyethylene (PE) pressure
pipes-Test of resistance to pull-out.|
|BDS ISO 3503|Assembled joints between fittings and polyethylene (PE) pressure
pipes-Test of leak proofness under internal pressure when
subjected to bending.|
|BDS ISO 3633|Plastics piping systems for soil and waste discharge (low and high
temperature) inside buildings-Specifications.|
|BDS ISO 6964|Polyolefin pipes and fittings-Determination of carbon black
content by calcinations and pyrolysis-Test method and basic
specification.|
|BDS ISO 4065|Thermoplastics pipes- Universal wall thickness table.|
|BDS ISO /TR
4191|Unplasticized polyvinylchloride (PVC-U) pipes for water supply-
Recommended practice for laying.|
|BDS ISO 4422-1|Pipes and fittings made of unplasticized polyvinylchloride (PVC-
U) for water supply-Specifications-Part 1: General.|
|BDS ISO 4422-2|Pipes and fittings made of unplasticized polyvinylchloride (PVC-
U) for water supply-Specifications-Part 2: Pipes (with or without
integral sockets).|
|BDS ISO 4422-3|Pipes and fittings made of unplasticized polyvinylchloride (PVC-
U) for water supply- Specifications-Part 3: Fittings and joints.|
|BDS ISO 4422-4|Pipes and fittings made of unplasticized polyvinylchloride (PVC-
U) for water supply- Specifications- Part 4: Valves and ancillary
equipment.|
|BDS ISO 4422-5|Pipes and fittings made of unplasticized polyvinylchloride (PVC-
U) for water supply- Specifications- Part 5: Fitness for purpose of
the system.|
|BDS ISO 4433-3|Thermoplastics
pipes-
Resistance
to
liquid
chemicals-
Classification-Part 3: Unplasticized polyvinylchloride (PVC-U),
high- impact polyvinylchloride (PVC-HI) and chlorinated
polyvinylchloride (PVC -C) pipes.|
|BDS ISO 4435|Plastic piping systems for non- pressure underground drainage
and sewerage- Unplasticized polyvinylchloride (PVC-U).|
|BDS ISO 4439|Unplasticized polyvinylchloride (PVC) pipes and fittings-
Determination and specification of density.|
|BDS ISO 6259-1|Thermoplastics pipes-Determination of tensile properties-Part 1:
General test method.|
|BDS ISO 6259-2|Thermoplastics pipes-Determination of tensile properties- Part 2:
Pipes made of unplasticized polyvinylchloride (PVC-U),
Chlorinated
polyvinylchloride
(PVC-C),
and
high-impact
polyvinylchloride (PVC-HI).|
|BDS ISO 6992|Unplasticized polyvinylchloride (PVC-U) pipes for drinking
water supply-Extractability of cadmium and mercury occurring as
impurities.|
|BDS ISO 9624|Thermoplastics
pipes
for
fluids
under
pressure-Mating
dimensions of flange adapters and loose backing flanges.|
|BDS ISO 11413|Plastics pipes and fittings-Preparation of test piece assemblies
between a polyethylene (PE) pipe and an electro fusion fitting
BDS ISO 11414, Plastics pipes and fittings-Preparation of
polyethylene (PE) pipe/pipe or pipe/fitting test piece assemblies
by butt fusion.|
|BDS ISO 12176-2|Plastics pipes and fittings-Equipment for fusion jointing
polyethylene systems-Part 2: Electro fusion|
|BDS ISO 12176-3|Plastics pipes and fittings-Equipment for fusion jointing
polyethylene systems-Part 3: Operator’s badge.|
|BDS ISO 12176-4|Plastics pipes and fittings-Equipment for fusion jointing
polyethylene systems-Part 4: Traceability coding.|
|BDS ISO 13479|Polyolefin pipes for the conveyance of fluids-Determination of
resistance to crack propagation-Test method for slow crack
growth on notched pipes (notch test).|
|BDS ISO 13761|Plastics pipes and fittings-Pressure reduction factors for
polyethylene pipeline systems for use at temperatures above
20°C.|
|BDS ISO 13951|Plastics piping systems-Test method for the resistance of
polyolefin pipe/pipe or pipe/fitting assemblies to tensile loading.|
|BDS ISO 13953|Polyethylene (PE) pipes and fittings-Determination of the tensile
strength and failure mode of test pieces from a butt-fused joint.|
|BDS ISO 13954|Plastics pipes and fittings-Peel de-cohesion test for polyethylene (PE) electro fusion assemblies of nominal outside diameter
greater than or equal to 90 mm.|
|BDS ISO 13955|Plastics pipes and fittings-Crushing de-cohesion test for
polyethylene (PE) electro fusion assemblies.|
|BDS ISO 13957|Plastics pipes and fittings-Polyethylene (PE) tapping tees-Test
method for impact resistance.|
|BDS ISO 14236|Plastics pipes and fittings-Mechanical-joint compression fittings
for use with polyethylene pressure pipes in water supply systems.|
|BDS ISO 18553|Method for the assessment of the degree of pigment or carbon
black dispersion in polyolefin pipes, fittings and compounds.|
|BDS ISO 18553|Method for the assessment of the degree of pigment or carbon
black dispersion in polyolefin pipes, fittings and compounds
Amendment 1:2010.|
|BDS ISO 4427-1|Plastics piping systems-Polyethylene (PE) pipes and fittings for
water supply-Part 1: General.|
|BDS ISO 4427-2|Plastics piping systems-Polyethylene (PE) pipes and fittings for
water supply-Part 2: Pipes.|
|BDS ISO 4427-3|Plastics piping systems-Polyethylene (PE) pipes and fittings for
water supply-Part 3: Fittings.|
|BDS ISO 4427-5|Plastics piping systems-Polyethylene (PE) pipes and fittings for
water supply-Part 5: Fitness for purpose of the system.|
|BDS ISO 4427-1|Plastics piping systems-Polyethylene (PE) pipes and fittings for
water
supply-Part
1:
General
Technical
corrigendum
1: 2010.|
|BDS ISO 3458|Assembled joints between fittings and polyethylene (PE) pressure
pipes-Test of leak proofness under internal pressure.|
|BDS ISO 3459|Polyethylene
(PE)
pressure
pipes-Joints
assembled
with
mechanical fittings-Internal under pressure test method and
requirement.|
|ASTM A53/A53M|Standard Specification for Pipe, Steel, Black and Hot-Dipped,
Zinc-Coated, Welded and Seamless.|
|ASTM A74|Standard Specification for Cast Iron Soil Pipe and Fittings.|
|ASTM A377|Standard Index of Specifications for Ductile-Iron Pressure Pipe.|
|ASTM B42|Standard Specification for Seamless Copper Pipe, Standard Sizes.|
|ASTM B43|Standard Specification for Seamless Red Brass Pipe, Standard
Sizes.|
|ASTM B75|Standard Specification for Seamless Copper Tube.|
|ASTM B88|Standard Specification for Seamless Copper Water Tube.|
|ASTM B251|Standard Specification for General Requirements for Wrought
Seamless Copper and Copper-Alloy Tube.|
|ASTM B302|Standard Specification for Thread-less Copper Pipe, Standard
Sizes.|
|ASTM B306|Standard Specification for Copper Drainage Tube (DWV).|
|ASTM B429/B429M|Standard Specification for Aluminum-Alloy Extruded Structural Pipe and Tube.|
|ASTM B447|Standard Specification for Welded Copper Tube.|
|ASTM B745/B745M|Standard Specification for Corrugated Aluminum Pipe for Sewers and Drains.|
|ASTM C14|Standard Specification for Non-reinforced Concrete Sewer, Storm
Drain, and Culvert Pipe.|
|ASTM C76|Standard Specification for Reinforced Concrete Culvert, Storm
Drain, and Sewer Pipe.|
|ASTM C654|Standard Specification for Porous Concrete Pipe.|
|ASTM C700|Standard Specification for Vitrified Clay Pipe, Extra Strength,
Standard Strength, and Perforated.|
|ASTM D1527|Standard
Specification
for
Acrylonitrile-Butadiene-Styrene
(ABS) Plastic Pipe, Schedules 40 and 80.|
|ASTM D1785|Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic
Pipe, Schedules 40, 80, and 120.|
|ASTM D2239|Standard Specification for Polyethylene (PE) Plastic Pipe (SIDR-
PR) Based on Controlled Inside Diameter.|
|ASTM D2241|Standard Specification for Poly(Vinyl Chloride) (PVC) Pressure-
Rated Pipe (SDR Series).|
|ASTM D2321|Standard Practice for Underground Installation of Thermoplastic
Pipe for Sewers and Other Gravity-Flow Applications ASTM
D2464 Standard Specification for Threaded Polyvinyl Chloride
(PVC) Plastic Pipe Fittings, Schedule 80.|
|ASTM D2466|Standard Specification for Polyvinyl Chloride (PVC) Plastic Pipe
Fittings, Schedule 40ASTM D2467 Standard Specification for
Poly(Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 80.|
|ASTM D2609|Standard Specification for Plastic Insert Fittings for Polyethylene
(PE) Plastic Pipe.|
|ASTM D2661|Standard
Specification
for
Acrylonitrile-Butadiene-Styrene
(ABS) Schedule 40 Plastic Drain, Waste, and Vent Pipe and
Fittings.|
||Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic|
|ASTM D2665|Drain, Waste, and Vent Pipe and Fittings.|
|ASTM D2672|Standard Specification for Joints for IPS PVC Pipe Using Solvent
Cement.|
|ASTM D2729|Standard Specification for Poly(Vinyl Chloride) (PVC) Sewer
Pipe and Fittings.|
|ASTM D2737|Standard Specification for Polyethylene (PE) Plastic Tubing.|
|ASTM D2751|Standard
Specification
for
Acrylonitrile-Butadiene-Styrene
(ABS) Sewer Pipe and Fittings.|
|ASTM D2846/D2846M|Standard Specification for Chlorinated Poly(Vinyl Chloride) (CPVC) Plastic Hot- and Cold-Water Distribution Systems.|
|ASTM D2949|Standard Specification for 3.25-in. Outside Diameter Poly(Vinyl Chloride) (PVC) Plastic Drain, Waste, and Vent Pipe and
Fittings.|
|ASTM D3034|Standard Specification for Type PSM Poly(Vinyl Chloride)
(PVC) Sewer Pipe and Fittings.|
|ASTM F405|Standard Specification for Corrugated Polyethylene (PE) Pipe
and Fittings.|
|ASTM F409|Standard Specification for Thermoplastic Accessible and
Replaceable Plastic Tube and Tubular Fittings.|
|ASTM F437|Standard Specification for Threaded Chlorinated Poly(Vinyl
Chloride) (CPVC) Plastic Pipe Fittings, Schedule 80.|
|ASTM F438|Standard Specification for Socket-Type Chlorinated Poly(Vinyl
Chloride) (CPVC) Plastic Pipe Fittings, Schedule 40.|
|ASTM B209|Standard Specification for Aluminum and Aluminum-Alloy Sheet
and Plate.|
|ASTM F441/F441M|Standard Specification for Chlorinated Poly(Vinyl Chloride) (CPVC) Plastic Pipe, Schedules 40 and 80.|
|ASTM
F442/F442M|Standard Specification for Chlorinated Poly(Vinyl Chloride)
(CPVC) Plastic Pipe (SDR-PR).|
|ASTM F628|Standard
Specification
for
Acrylonitrile-Butadiene-Styrene
(ABS) Schedule 40 Plastic Drain, Waste, and Vent Pipe With a
Cellular Core.|
|ASTM F891|Standard Specification for Coextruded Poly(Vinyl Chloride)
(PVC) Plastic Pipe With a Cellular Core.|
|IS 404 (Part-I)|Specification for lead pipes Part I for other than chemical
purpose.|
|ISO 2531|Ductile Iron pipes, fittings and accessories for pressure pipelines.|
|ASME/ANSI
B16.3|Malleable iron threaded fittings: Classes 150 and 300.|
|ASME/ANSI B16.485|Cast Iron threaded fittings.|
|ASME/ANSI B16.9|Factory made wrought steel butt welding fittings.|
|ASME/ANSI B16.11|Forged Steel Fittings, Socket-Welding and Threaded.|
|ASME/ABSI B16.12|Cast-Iron Threaded Drainage Fittings;|
|ASME/ANSI
B16.15|Cast Copper Alloy Threaded Fittings: Classes 125 and 250.|
|ASME/ANSI
B16.18|Cast Copper Alloy Solder Joint Pressure Fittings.|
|ASME/ANSI
B16.22|Wrought Copper and Copper Alloy Solder Joint Pressure Fittings.|
|ASME/ANSI B16.23|Cast Copper Alloy Solder Joint Drainage Fittings (DWV).|
|ASME/ANSI
B16.28|Wrought Steel Butt welding Short radius Elbows and Returns.|
|ASME/ANSI B16.29|Wrought Copper and Wrought Copper Alloy Solder Joint Fittings for solvent Drainage Systems.|
|ASME/ANSI B16.32|Cast Copper Alloy Solder Joint Fittings for Solvent Drainage Systems.|
|AWWA C110|Standard for Grey Iron and Ductile Iron Fittings, 76 mm to 1220
mm (3 in. through 48 inches), for Water and Other Liquids.|
### **2.15.3 Joints and Connections Between Pipes and Fittings**
Applicable standards for joints and connections between pipes and fittings are listed below:
| Item | Description |
| ----------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS EN 681-1 | Elastomeric seals-Materials requirements for pipe joint seals used
in water and drainage applications-Part 1: Vulcanized rubber. |
| BDS EN 681-2 | Elastomeric seals-Materials requirements for pipe joint seals used
in water and drainage applications-Part 2: Thermoplastic
elastomers. |
| ASTM B42 | Standard Specification for Seamless Copper Pipe, Standard Sizes. |
| ASTM C425 | Standard Specification for Compression Joints for Vitrified Clay
Pipe and Fittings. |
| ASTM C443 | Standard Specification for Joints for Concrete Pipe and
Manholes, Using Rubber Gaskets. |
| ASTM C564 | Standard Specification for Rubber Gaskets for Cast Iron Soil Pipe
and Fittings. |
| ASTM D2235 | Standard Specification for Solvent Cement for Acrylonitrile-
Butadiene-Styrene (ABS) Plastic Pipe and Fittings. |
| ASTM D2564 | Standard Specification for Solvent Cements for Poly(Vinyl
Chloride) (PVC) Plastic Piping Systems. |
| ASTM D2657 | Standard Practice for Heat Fusion Joining of Polyolefin Pipe and
Fittings. |
| ASTM D2661 | Standard
Specification
for
Acrylonitrile-Butadiene-Styrene
(ABS) Schedule 40 Plastic Drain, Waste, and Vent Pipe and
Fittings. |
| ASTM D2846/D2846M | Standard Specification for Chlorinated Poly(Vinyl Chloride) (CPVC) Plastic Hot- and Cold-Water Distribution Systems. |
| ASTM D2855 | Standard Practice for Making Solvent-Cemented Joints with
Poly(Vinyl Chloride) (PVC) Pipe and Fittings. |
| ASTM D3139 | Standard Specification for Joints for Plastic Pressure Pipes Using
Flexible Elastomeric Seals. |
| ASTM D3212 | Standard Specification for Joints for Drain and Sewer Plastic
Pipes Using Flexible Elastomeric Seals. |
| ASTM F402 | Standard Practice for Safe Handling of Solvent Cements,
Primers, and Cleaners Used for Joining Thermoplastic Pipe and
Fittings. |
| ASTM F493 | Standard Specification for Solvent Cements for Chlorinated
Poly(Vinyl Chloride) (CPVC) Plastic Pipe and Fittings. |
| ASTM F628 | Standard
Specification
for
Acrylonitrile-Butadiene-Styrene
(ABS) Schedule 40 Plastic Drain, Waste, and Vent Pipe With a
Cellular Core. |
| ASTM F656 | Standard Specification for Primers for Use in Solvent
Cement Joints of Poly(Vinyl Chloride) (PVC) Plastic Pipe and
Fittings. |
| ASME/ANSI B1.20.1 | Pillar taps used in water supply. |
### **2.15.4 Taps and Valves**
Taps and valves shall conform to the following Standards:
| Item | Description |
| ------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BDS 987 | Sand cast brass screw‐down bib taps and stop taps for water
services. |
| | It covers the requirements regarding materials, dimensions,
constructions, workmanship, finish and testing of tapes for water
services. |
| BDS 1507 | Bib taps used in water supply. |
| BDS 1508 | Stop taps used in water supply specifies the requirements,
dimensions construction, materials and test methods of stop taps
used in water supply. |
| BDS 1509 | Pillar taps used in water supply. |
| BDS EN 200 | Sanitary tapware-Single taps and combination taps for water
supply systems of type 1 and type 2-General technical
specification. |
| BDS EN 246 | Sanitary
tapware-General
specifications
for
flow
rate
regulators. |
| BDS EN 248 | Sanitary tapware-General specification for electrodeposited
coatings of Ni‐Cr. |
| BDS EN 1112 | Sanitary tapware ‐ Shower outlets for sanitary tapware for water
supply systems of type 1 and type 2-General technical
specification. |
| BDS EN 1113 | Sanitary tapware-Shower hoses for sanitary tapware for water
supply systems of type 1 and type 2-General technical
specification. |
| BS 1212 (3 Parts) | Specification for Float Operated Valves (excluding floats). |
| BS 1010 | Specification for draw-off taps and stop valves for water
services. |
| BS 1968 | Specification for floats for ball valves (copper). |
| BS 5433 | Specification for underground stop valves for water services
(copper). |
| BS 2456 | Specification for floats for ball valves (plastic) for cold and hot
water. |
| BS 1415 ( 2 parts) | Mixing valves (manually operated). |
| BS 5163 | Specification for predominantly key-operated cast iron wedge
gate valve for water works. |
| BS 3377 | Specification for boilers for use with domestic solid mineral fuel
appliances. |
| BS 843 | Specification for thermal storage electric water heaters. |
| BS 855 | Specification for welded steel boilers for central heating and
indirect hot water supply. |
## **2.16 Miscellaneous Materials**
### **2.16.1 Ferrocement**
Details including material requirements are given in Chapter 12 Part 6.
### **2.16.2 Plastics**
Plastics may be used in buildings or structures as light transmitting materials such as glazing, skylights, lighting lenses, luminous ceilings, roof panels, signs and similar purposes. Foam plastics are also used in buildings.
Applicants for approval of a plastic material shall furnish all necessary technical data required by the Building Official. The data shall include chemical composition; applicable physical, mechanical and thermal properties such as fire resistance, flammability and flame spread; weather resistance; electrical properties; products of combustion; and coefficient of expansion.
The requirements for light transmitting plastics, including roof panels and foam plastics are given below.
#### 2.16.2.1 Light Transmitting Plastics
An approved light transmitting plastic shall be any thermoplastic, thermosetting or reinforced thermosetting plastic material which has a self-ignition temperature of $343^\circ\text{C}$ or greater when tested in accordance with, Test Method for Ignition Properties of Plastics; a smoke density rating not greater than 450 when tested in the manner intended for use in accordance with ASTM E84 Test Method for Surface Burning Characteristics of Building Materials; or not greater than 75 when tested in the thickness intended for use in accordance with ASTM D2843 Test Method for Density of Smoke from the Burning or Decomposition of Plastics; and which conforms to one of the following combustibility classifications:
Class C1 : Plastic materials which have a burning extent of 25 mm or less when tested at a nominal thickness of 1.5 mm, or in the thickness intended for use, in accordance with ASTM D635 Test Method for Rate of Burning and/or Extent and Time of Burning of Self-Supporting Plastics in Horizontal Position; or
Class C2: Plastic materials which have a burning rate of 63 mm/min or less when tested at a nominal thickness of 1.5 mm, or in the thickness intended for use, in accordance with ASTM D635.
#### 2.16.2.2 Foam Plastics
All foam plastics and foam plastic cores of manufactured assemblies shall have a flame spread rating of not more than 75 and shall have a smoke developed rating of not more than 450 when tested in the maximum thickness intended for use in accordance with ASTM E84.
All foam plastics, unless otherwise indicated in this Section, shall be separated from the interior of a building by an approved thermal barrier of 13 mm gypsum wall board or equivalent thermal barrier material which will limit the average temperature rise of the unexposed surface to not more than $121^\circ\text{C}$ after 15 minutes of fire exposure complying with the standard time-temperature curve of ASTM E119 Test Methods for Fire Tests of Building Construction and Materials. The thermal barrier shall be installed in such a manner that it will stay in place for a minimum of 15 minutes under the same testing conditions. The thermal barrier is not required when the foam plastic is protected by a 25 mm minimum thickness of masonry or concrete.
#### 2.16.2.3 Applicable Standards
A list of applicable Standards for plastics is given below:
| Item | Description |
| ---------- | ------------------------------------------------------------------------------------------------------------------------ |
| BDS 885 | Method for measuring viscosity number and K-value of PVC
resins. |
| BDS 886 | Method for direct measuring the specific gravity of plastics. |
| BDS 887 | Method for measuring deformation under heat of flexible rigid PVC
compounds. |
| BDS 888 | Method for measuring temperature of deflection under load. |
| BDS 889 | Method for measuring the Vicat Softening Temperature (VST) of
thermoplastics. |
| BDS 890 | Method for measuring the water absorption at room temperature and
boiling water absorption of plastics. |
| BDS 891 | Method for measuring the flexural modulus of plastics. |
| BDS 892 | Method for measuring the resistance to tear propagation of flexible
plastics, film or sheeting. |
| ASTM D543 | Standard Practices for Evaluating the Resistance of Plastics to
Chemical Reagents. |
| ASTM D635 | Standard Test Method for Rate of Burning and/or Extent and Time
of Burning of Plastics in a Horizontal Position. |
| ASTM D638 | Standard Test Method for Tensile Properties of Plastics. |
| ASTM D695 | Standard Test Method for Compressive Properties of Rigid Plastics. |
| ASTM D882 | Standard Test Method for Tensile Properties of Thin Plastic
Sheeting. |
| ASTM D1003 | Standard Test Method for Haze and Luminous Transmittance of
Transparent Plastics. |
| ASTM D1044 | Standard Test Method for Resistance of Transparent Plastics to
Surface Abrasion. |
| ASTM D1204 | Standard Test Method for Linear Dimensional Changes of Non-rigid Thermoplastic Sheeting or Film at Elevated Temperature. |
| ASTM D1593 | Standard Specification for Non-rigid Vinyl Chloride Plastic Film
and Sheeting. |
| ASTM D2103 | Standard Specification for Polyethylene Film and Sheeting. |
| ASTM D2126 | Standard Test Method for Response of Rigid Cellular Plastics to
Thermal and Humid Aging. |
| ASTM D2842 | Standard Test Method for Water Absorption of Rigid Cellular
Plastics. |
| ASTM D2843 | Standard Test Method for Density of Smoke from the Burning or
Decomposition of Plastics. |
| ASTM D3294 | Standard Specification for PTFE Resin Molded Sheet and Molded
Basic Shapes. |
| ASTM D3678 | Standard Specification for Rigid Poly(Vinyl Chloride) (PVC)
Interior-Profile Extrusions. |
| ASTM D3679 | Standard Specification for Rigid Poly(Vinyl Chloride) (PVC)
Siding. |
| ASTM D3841 | Standard Specification for Glass-Fiber-Reinforced Polyester Plastic
Panels. |
| ASTM D4802 | Standard Specification for Poly(Methyl Methacrylate) Acrylic
Plastic Sheet. |
| ASTM E84 | Standard Test Method for Surface Burning Characteristics of
Building Materials. |
| ASTM E119 | Standard Test Methods for Fire Tests of Building Construction and
Materials. |
### **2.16.3 Ballies and Wood Poles**
Ballies of Sal/Gazari, Sundari and Garjan are used in building construction. These shall be free from rots, knots and sap, and straight and uniform in size. These should conform to the following Standards:
| Item | Description |
| -------- | ----------------------------------------------------------------------------------------------- |
| BDS 809 | Specification for wood poles for overhead power and telecommunication lines. |
| ASTM D25 | Standard Specification for Round Timber Piles. |
| IS 3337 | Specification for Ballies for general purposes. |
| IS 1900 | Method of testing wood poles. |
| IS 6711 | Code of practice for maintenance of wood poles for overhead power and telecommunications lines. |
### **2.16.4 Bamboos**
The following standards shall be applicable for bamboos used for structural and nonstructural purposes:
IS 1902 Code of Practice for Preservation of Bamboo and Cane for Nonstructural Purposes; IS 6874 Method of Tests for Round Bamboos. IS 8242 Methods of Tests for Split Bamboo. IS 8295 Specification for Bamboo Chicks, Part I Fine. IS 9096 Code of Practice for Preservation of Bamboos for Structural Purposes.
### **2.16.5 Fillers, Stoppers and Putties**
These shall conform to the following standards:
* IS 110 Specification for ready mixed paint, brushing, grey filler, for enamels, for use over primers.
* IS 345 Specification for wood filler, transparent, liquid. IS 419 Specification for putty for use on window frames. IS 421 Specification for jointing paste, for bedding moldings on coaching stock.
* IS 423 Specification for plastic wood, for joiners' filler. IS 424 Specification for plastic asphalt. IS 3709 Specification for mastic cement for bedding of metal windows.
IS 7164 Specification for Stopper.
### **2.16.6 Wire Ropes and Wire Products**
These materials shall conform to the following standards:
| Item | Description |
| ---------- | -------------------------------------------------------------------------------------------------------------------- |
| ASTM A116 | Standard Specification for Zinc-Coated (Galvanized) Steel Woven
Wire Fence Fabric. |
| ASTM A121 | Standard Specification for Metallic-Coated Carbon Steel Barbed
Wire. |
| ASTM A368 | Standard Specification for Stainless Steel Wire Strand. |
| ASTM A392 | Standard Specification for Zinc-Coated Steel Chain-Link Fence
Fabric. |
| ASTM A475 | Standard Specification for Zinc-Coated Steel Wire Strand. |
| ASTM A492 | Standard Specification for Stainless Steel Rope Wire. |
| ASTM A510 | Standard Specification for General Requirements for Wire Rods and
Coarse Round Wire, Carbon Steel. |
| ASTM A586 | Standard Specification for Zinc-Coated Parallel and Helical Steel
Wire Structural Strand. |
| ASTM A603 | Standard Specification for Zinc-Coated Steel Structural Wire Rope. |
| ASTM A817 | Standard Specification for Metallic-Coated Steel Wire for Chain-
Link Fence Fabric. and Marcelled Tension Wire. |
| ASTM A824 | Standard Specification for Metallic-Coated Steel Marcelled Tension
Wire for Use With Chain Link Fence. |
| ASTM F1183 | Standard Specification for Aluminum Alloy Chain Link Fence
Fabric. |
| IS 2365 | Specification for Steel Wire Suspension Ropes for Lifts, Elevators
and Hoists. |
### **2.16.7 Waterproofing and Damp-proofing Materials**
Waterproofing and damp-proofing materials shall conform to the following standards:
| Item | Description |
| -------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| ASTM D41 | Standard Specification for Asphalt Primer Used in Roofing, Damp
proofing, and Waterproofing. |
| ASTM D43 | Standard Specification for Coal Tar Primer Used in Roofing,
Damp proofing, and Waterproofing. |
| ASTM D146 | Standard Test Methods for Sampling and Testing Bitumen-Saturated
Felts
and
Woven
Fabrics
for
Roofing
and
Waterproofing. |
| ASTM D173 | Standard Specification for Bitumen-Saturated Cotton Fabrics Used
in Roofing and Waterproofing. |
| ASTM D6380 | Standard Specification for Asphalt Roll Roofing (Organic Felt). |
| ASTM
D226/D226M | Standard Specification for Asphalt-Saturated Organic Felt Used in
Roofing and Waterproofing. |
| ASTM D227 | Standard Specification for Coal-Tar-Saturated Organic Felt Used
in Roofing and Waterproofing. |
| ASTM D449 | Standard Specification for Asphalt Used in Damp proofing and
Waterproofing. |
| ASTM D450 | Standard Specification for Coal-Tar Pitch Used in Roofing, Damp
proofing, and Waterproofing. |
| ASTM D1327 | Standard Specification for Bitumen-Saturated Woven Burlap
Fabrics Used in Roofing and Waterproofing. |
| ASTM D1668 | Standard Specification for Glass Fabrics (Woven and Treated) for
Roofing and Waterproofing. |
| ASTM D2178 | Standard Specification for Asphalt Glass Felt Used in Roofing and
Waterproofing. |
| ASTM D2626 | Standard Specification for Asphalt-Saturated and Coated Organic
Felt Base Sheet Used in Roofing. |
| ASTM D3468 | Standard
Specification
for
Liquid-Applied
Neoprene
and Chloro-sulfonated
Polyethylene
Used
in
Roofing
and
Waterproofing. |
### **2.16.8 Glazed Tiles and Tile-setting Mortars**
Glazed tiles shall conform to the following standards:
| Item | Description |
| ----------- | ------------------------------------------------------------------------------------------------------------------ |
| BDS 1301 | Specification for glazed earthenware wall tiles. |
| ASTM C126 | Standard Specification for Ceramic Glazed Structural Clay Facing
Tile, Facing Brick, and Solid Masonry Units. |
| ANSI A137.1 | Specification for Ceramic Tile. |
| BS 6431 | Ceramic floor and wall tiles (Part 1 to 23). |
#### 2.16.8.1 Mortars for Ceramic Wall and Floor Tile
* (a) Portland Cement Mortars: Portland cement mortars for installing ceramic wall and floor tile shall comply with ANSI A108.1 and be of the compositions indicated in Table 5.2.1.
* (b) Dry-set Portland Cement Mortars: Premixed prepared Portland cement mortars, which require only the addition of water and which are used in the installation of ceramic tile, shall comply with ANSI A 118.1. The shear bond strength for tile set in such mortar shall be as required in accordance with that standard. Tile set in dry-set Portland cement mortar shall be installed in accordance with ANSI A 108.5.
* (c) Electrically Conductive Dry-Set Mortars: Premixed prepared Portland cement mortars, which require only the addition of water and which comply with ANSI A118.2, shall be used in the installation of electrically conductive ceramic tile. Tile set in electrically conductive dry-set mortar shall be installed in accordance with ANSI A 108.7.
* (d) Latex-modified Portland Cement Mortars: Latex-modified Portland cement thin set mortars in which Lalex is added to dry-set mortar as a replacement for all or part of the gauging water which are used for the installation of ceramic tile shall comply with ANSI A 118.4. Tile set in latex-modified Portland cement mortar shall be installed in accordance with ANSI A 108.5.
* (e) Epoxy Mortar: Chemical-resistant epoxy for setting and grouting ceramic tile shall comply with ANSI A 118.3-2009. Tile set and grouted with epoxy shall be installed in accordance with ANSI A 108.6.
* (f) Furan Mortar and Grout: Chemical resistant furan mortar and grout which are used to install ceramic tile shall comply with ANSI A 118.5. Tile set and grouted with furan shall be installed in accordance with ANSI A 108.8.
* (g) Modified Epoxy-Emulsion Mortar and Grout: Modified epoxy-emulsion mortar and grout which are used to install ceramic tile shall comply with
ANSI A 118.8. Tile set and grouted with modified epoxy-emulsion mortar and grout shall be installed in accordance with ANSI A 108.9.
* (h) Organic Adhesives: Water-resistant organic adhesives used for the installation of ceramic tile shall comply with ANSI A 136.1. The shear bond strength after water immersion shall not be less than 0.25 $\text{kN/mm}^2$ for Type I adhesive, and not less than 0.13 $\text{kN/mm}^2$ for Type II adhesive when tested in accordance with ANSI A 136.1. Tile set in organic adhesive shall be installed in accordance with ANSI A 108.4.
* (i) Portland Cement Grouts: Portland cement grouts used for the installation of ceramic tile shall comply with ANSI A 118.6. Portland cement grouts for tile work shall be installed in accordance with ANSI A 108.10.
#### 2.16.8.2 Applicable Standards
A list of applicable Standards for tiles, mortars and adhesives is given below:
| Item | Description |
| ---------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------ |
| BDS 1301 | Specification for Glazed Earthenware Wall Tiles. |
| ASTM C126 | Standard Specification for Ceramic Glazed Structural Clay
Facing Tile, Facing Brick, and Solid Masonry Units. |
| ANSI A108.1 | Specification for the Installation of Ceramic Tile with Portland
Cement Mortar. |
| ANSI A108.4 | Installation of Ceramic Tile with Organic Adhesives or Water
Cleanable Tile Setting Epoxy Adhesive. |
| ANSI A108.5 | Installation of Ceramic Tile with Dry-Set Portland Cement
Mortar or Latex-Portland Cement Mortar. |
| ANSI A108.6 | Installation of Ceramic Tile with Chemical Resistant, Water
Cleanable Tile Setting and Grouting Epoxy. |
| ANSI A108.7 | Specification for Electrically Conductive Ceramic Tile Installed
with Conductive Dry-Set Portland Cement Mortar. |
| ANSI A108.8 | Installation of Ceramic Tile with Chemical Resistant Furan
Mortar and Grout. |
| ANSI A108.9 | Installation of Ceramic Tile with Modified Epoxy Emulsion
Mortar/Grout. |
| ANSI A108.10 | Installation of Grout in Tile work. |
| ANSI A118.1
ANSI A118.2 | Specification for Dry-Set Portland Cement Mortar.
Specifications for Conductive Dry-set Portland Cement Mortar. |
| ANSI A118.3 | Specifications for Chemical Resistant Water Cleanable Tile
Setting and Grouting Epoxy and Water Cleanable Tile Setting
Epoxy Adhesive. |
| ANSI A118.4 | Specifications Furan Latex-Portland Cement Mortar. |
| ANSI A118.5 | Specifications for Chemical Resistant Furan. |
| ANSI A118.6 | Specifications for Ceramic Tile Grouts. |
| ANSI A118.8 | Specifications for Modified Epoxy Emulsion Mortar/Grout. |
| ANSI A136.1 | Organic Adhesives for Installation of Ceramic Tile. |
| ANSI A137.1 | Specifications for Ceramic Tile. |
| BS 6431 | Floor and wall tiles. |
| BS 6431 Part 1 | Specification for classification and making, including definitions
and characteristics. |
| BS 6431 Part 2 | Specification for struded ceramic tiles with low water absorption
(E\< 3%) Group A1. |
| BS 6431 Part 3 | Extruded ceramic tiles with a water absorption of 3% \< 6%.
Group A 11a. |
| BS 6431 Part 3
Sec 3.1 | Specification for general products. |
| BS 6431 Part 3
Sec 3.2 | Specification for products Terre Cuite, Cotto, Baldosion Catalan. |
| BS 6431 Part 4 | Extruded Ceramic Tiles with a Water Absorption of 6% \10%. Group A11b. |
| BS 6431 Part 4 | Specification for General Products. |
| BS 6431 Part 4
Sec 4.2 | Specification for Specific Products (Terre Cuite, Cotto,
Baldosion Catalan). |
| BS 6431 Part 5 | Specification for extruded ceramic tiles with a water absorption
of E>10%, Group A111. |
| BS 6431 Part 6 | Specification for dust-pre-stressed ceramic tiles with a low-water
absorption (E\<3%) Group B1. |
| BS 6431 Part 7 | Specification for dust-pre-stressed ceramic tiles with a water
absorption of 3% \absorption of 6% \< E ≤10%. Group B11b; |
| BS 6431 Part 9 | Specification for dust-pre-stressed ceramic tiles with a water
absorption of E >10%. Group B111. |
| BS 6431 Part 10 | Method for determination of dimensions and surface quality. |
| BS 6431 Part 11 | Method for determination of water absorption. |
| BS 6431 Part 12 | Method for determination of modulus of. |
| BS 6431 Part 13 | Method for determination of scratch hardness of surface
according to Mhos. |
| BS 6431 Part 14 | Method for determination of resistance to abrasion of unglazed
tiles. |
| BS 6431 Part 15 | Method for determination of linear thermal expansion. |
| BS 6431 Part 16 | Method for determination of resistance to thermal shock. |
| BS 6431 Part 17 | Method for determination of crazing resistance-glazed tiles. |
| BS 6431 Part 18 | Method for determination of chemical resistance-unglazed
tiles. |
| BS 6431 Part 19 | Method for determination of chemical resistance-glazed
tiles. |
| BS 6431 Part 20 | Method for determination of resistance to surface abrasion-
glazed tiles. |
| BS 6431 Part 23 | Specification for sampling and basis for acceptance. |
### **2.16.9 Refractories**
Refractories shall conform to the following Standards:
| Item | Description |
| ---------- | -------------------------------------------------------------------------------------------------------------------------- |
| BDS 1493 | Glossary of terms used in refractory. |
| BDS 1494 | Dimension of refractory bricks. |
| BDS 1495 | High aluminum refractory bricks. |
| ISO 528 | Refractory products-determination of pyrometric cone equivalent
(refractoriness). |
| ISO 1109 | Refractory products-classification of dense shaped refractory
products. |
| ISO 1146 | Pyrometric reference cones for laboratory use-specification. |
| ISO 1893 | Refractory products-determination of refractoriness-under-load
(differential with rising temperature). |
| ISO 1927 | Prepared unshaped refractory materials (dense and insulating)
classification. |
| ISO 2245 | Shaped insulating refractory products-classification. |
| ISO 2477 | Shaped
insulating
refractory
products-determination
of
permanent change in dimensions on heating. |
| ISO 2478 | Dense shaped refractory products-determination of permanent
change in dimensions on heating. |
| ISO 3187 | Refractory products-determination of creep in compression. |
| ISO 5013 | Refractory products-determination of modulus of rupture at
elevated temperatures. |
| ISO 5014 | Refractory products-determination of modulus of rupture at
ambient temperature. |
| ISO 5016 | Shaped insulating refractory products-determination of bulk
density and true porosity. |
| ISO 5017 | Dense shaped refractory products-determination of bulk density,
apparent porosity and true porosity. |
| ISO 5018 | Refractory materials-determination of true density. |
| ISO 5019-1 | Refractory bricks-dimensions-Part 1: Rectangular bricks. |
| ISO 5019-2 | Refractory bricks-dimensions-Part 2: Arch bricks; |
| ISO 5019-3 | Refractory bricks-dimensions-Part 3: Rectangular checker bricks
for regenerative furnace. |
| ISO 5419-4 | Refractory bricks-dimensions-Part 4: Dome bricks for electric
arc furnace roofs. |
| ISO 5015-6 | Refractory bricks-dimensions-Part 6: Basic bricks for oxygen
steel making converters. |
| ISO 5022 | Shaped refractory products-sampling and acceptance testing. |
| ISO 5417 | Refractory bricks for use in rotary kilns-dimensions. |
| ISO 8656 | Refractory products-sampling of raw materials and unshaped
products- Part 1: Sampling scheme. |
| ISO 8840 | Refractory materials-determination of bulk density of granular
materials (grain density). |
| ISO 8890 | Dense shaped refractory products-determination of resistance to
sulfuric acid. |
| ISO 8894-1 | Refractory materials-determination of thermal conductivity- Part
1: Hot-wire method (cross-array). |
| ISO 8894-2 | Refractory materials-determination of thermal conductivity- Part
2: Hot-wire method (parallel). |
| ISO 8895 | Shaped Insulating refractory products-determination of cold
crushing strength. |
| ISO 9205 | Refractory bricks for use in rotary kilns-hot-face identification
marking. |
| ISO 10080 | Refractory products-classification of dense, shaped acid-resisting
products. |
| ISO 10081 | Basic refractory products-classification- Part I: Products
containing less than 7% residual carbon. |
### **2.16.10 Thermal Insulating Materials**
Thermal insulation may be in the following physical forms:
* Loose fill dry granules or nodules poured or below in place;
* Flexible or semi rigid blankets and bolts of wool like material;
* Rigid boards and blocks;
* Membrane reflective insulation;
* Spray applied mineral fibre or insulating concrete;
* Poured in plain-insulating concrete;
* Foamed in place-polyurethane;
* Gypsum plaster.
Thermal insulating materials shall conform to the Standards listed below:
| Item | Description |
| --------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------- |
| ASTM C167 | Standard Test Methods for Thickness and Density of Blanket or Batt
Thermal Insulations. |
| ASTM C177 | Standard Test Method for Steady-State Heat Flux Measurements
and Thermal Transmission Properties by Means of the Guarded-
Hot-Plate Apparatus. |
| ASTM C195 | Standard Specification for Mineral Fiber Thermal Insulating
Cement. |
| ASTM C196 | Standard Specification for Expanded or Exfoliated Vermiculite
Thermal Insulating Cement |
| ASTM C208 | Standard Specification for Cellulosic Fiber Insulating Board. |
| ASTM C209 | Standard Test Methods for Cellulosic Fiber Insulating Board. |
| ASTM C1363 | Standard Test Method for Thermal Performance of Building
Materials and Envelope Assemblies by Means of a Hot Box
Apparatus. |
| ASTM C240 | Standard Test Methods of Testing Cellular Glass Insulation Block. |
| ASTM C335 | Standard Test Method for Steady-State Heat Transfer Properties of
Pipe Insulation. |
| ASTM C411 | Standard Test Method for Hot-Surface Performance of High-
Temperature Thermal Insulation. |
| ASTM C449 | Standard Specification for Mineral Fiber Hydraulic-Setting Thermal
Insulating and Finishing Cement. |
| ASTM C516 | Standard Specification for Vermiculite Loose Fill Thermal
Insulation. |
| ASTM C518 | Standard Test Method for Steady-State Thermal Transmission
Properties by Means of the Heat Flow Meter Apparatus. |
| ASTM C520 | Standard Test Methods for Density of Granular Loose Fill
Insulations. |
| ASTM C533 | Standard Specification for Calcium Silicate Block and Pipe Thermal
Insulation. |
| ASTM C534/C534M | Standard Specification for Preformed Flexible Elastomeric Cellular Thermal Insulation in Sheet and Tubular Form. |
| ASTM C547 | Standard Specification for Mineral Fiber Pipe Insulation. |
| ASTM C549 | Standard Specification for Perlite Loose Fill Insulation. |
| ASTM C552 | Standard Specification for Cellular Glass Thermal Insulation. |
| ASTM C553 | Standard Specification for Mineral Fiber Blanket Thermal Insulation
for Commercial and Industrial Applications. |
| ASTM C578 | Standard Specification for Rigid, Cellular Polystyrene Thermal
Insulation. |
| ASTM C591 | Standard Specification for Un-faced Preformed Rigid Cellular
Polyisocyanurate Thermal Insulation. |
| ASTM C592 | Standard Specification for Mineral Fiber Blanket Insulation and
Blanket-Type Pipe Insulation (Metal-Mesh Covered) (Industrial
Type). |
| ASTM C610 | Standard Specification for Molded Expanded Perlite Block and Pipe
Thermal Insulation. |
| ASTM C612 | Standard Specification for Mineral Fiber Block and Board Thermal
Insulation. |
| ASTM C665 | Standard
Specification
for
Mineral-Fiber
Blanket
Thermal
Insulation for Light Frame Construction and Manufactured Housing. |
| ASTM C726 | Standard Specification for Mineral Fiber Roof Insulation Board. |
| ASTM C728 | Standard Specification for Perlite Thermal Insulation Board. |
| ASTM C739 | Standard Specification for Cellulosic Fiber Loose-Fill Thermal
Insulation. |
| ASTM C764 | Standard Specification for Mineral Fiber Loose-Fill Thermal
Insulation. |
| ASTM C916 | Standard Specification for Adhesives for Duct Thermal Insulation. |
| ASTM C991 | Standard Specification for Flexible Fibrous Glass Insulation for
Metal Buildings. |
| ASTM C1014 | Standard Specification for Spray-Applied Mineral Fiber Thermal
and Sound Absorbing Insulation. |
| ASTM C1029 | Standard
Specification
for
Spray-Applied
Rigid
Cellular
Polyurethane Thermal Insulation. |
| ASTM C1071 | Standard Specification for Fibrous Glass Duct Lining Insulation
(Thermal and Sound Absorbing Material). |
### **2.16.11 Screw Threads and Rivets**
These shall conform to the following standards:
| Item | Description |
| -------- | -------------------------------------------------------------------------------------------- |
| IS 554 | Dimensions for pipe threads where pressure tight joints are required
on the threads. |
| IS 1929 | Specification for hot forged steel rivets for hot closing (12 to 36 mm
diameter). |
| IS 2155 | Specification for cold-forged solid steel rivets for hot closing (6 to 16
mm diameter). |
| IS 2643 | Dimensions for pipe threads for fastening purposes. |
| | Part I-Basic profile and dimensions. |
| | Part II-Tolerances. |
| | Part III-Limits of sizes. |
| IS 2907 | Specification for non-ferrous rivets (1.6 mm to 10 mm). |
| IS 2998 | Specification for cold forged steel rivets for cold closing (1 to 16 mm
diameter). |
| IS 10102 | Technical supply conditions for rivets. |
### **2.16.12 Sealants**
Sealants shall conform to the following Standards:
|ASTM C509|Standard Specification for Elastomeric Cellular Preformed Gasket
and Sealing Material.|
|ASTM C542|Standard Specification for Lock-Strip Gaskets.|
|ASTM C564|Standard Specification for Rubber Gaskets for Cast Iron Soil Pipe
and Fittings.|
|ASTM C716|Standard Specification for Installing Lock-Strip Gaskets and Infill
Glazing Materials.|
|ASTM C719|Standard Test Method for Adhesion and Cohesion of Elastomeric
Joint Sealants Under Cyclic Movement (Hockman Cycle).|
|ASTM C1193|Standard Guide for Use of Joint Sealants.|
|ASTM C794|Standard Test Method for Adhesion-in-Peel of Elastomeric Joint
Sealants.|
|ASTM C834|Standard Specification for Latex Sealants.|
|ASTM C864|Standard Specification for Dense Elastomeric Compression Seal
Gaskets, Setting Blocks, and Spacers.|
|ASTM C919|Standard Practice for Use of Sealants in Acoustical Applications.|
|ASTM C920|Standard Specification for Elastomeric Joint Sealants.|
|ASTM C1193|Standard Guide for Use of Joint Sealants.|
|ASTM D2628|Standard Specification for Preformed Polychloroprene Elastomeric
Joint Seals for Concrete Pavements.|
|ASTM D6690|Standard Specification for Joint and Crack Sealants, Hot Applied,
for Concrete and Asphalt Pavements.|
|ASTM D3406|Standard Specification for Joint Sealant, Hot-Applied, Elastomeric-
Type, for Portland Cement Concrete Pavements.|
|ASTM D3667|Standard Specification for Rubber Seals Used in Flat-Plate Solar
Collectors.|
|ASTM D3771|Standard Specification for Rubber Seals Used in Concentrating
Solar Collectors.|
|ASTM D3832|Standard Specification for Rubber Seals Contacting Liquids in Solar
Energy Systems.|
|ISO 3934|Rubber building gaskets-materials in preformed solid vulcanizates
used for sealing glazing and panels-specification.|
|ISO 4633|Rubber seals-joint rings for water supply, drainage and sewerage
pipelines-specifications for materials|
|ISO 4635|Rubber, vulcanized-preformed compression seals for use between
concrete motorway paving sections-specifications for material.|
|ISO 5892|Rubber Building Gaskets-Materials for Preformed Solid Vulcanized
Structural Gaskets-Specification;|
|ISO 6447|Rubber seals-joint rings used for gas supply pipes and fittings-
specification for material.|
|ISO 9331|Rubber seals joint rings for hot water supply pipelines up to $110^\circ\text{C}$
specifications for the material.|
### **2.16.13 Joints and Jointing Products**
Joints and jointing products shall conform to the following Standards:
| Item | Description |
| --------- | ------------------------------------------------------------------------------------------------------------------------------------ |
| ISO 2444 | Joints in buildings-vocabulary. |
| ISO 3867 | Agglomerated cork-material of expansion joints for construction and
building test-methods. |
| ISO 3869 | Agglomerated cork-filler material of expansion joints for construction
and buildings -characteristics, sampling and packing. |
| ISO 3934 | Rubber building gaskets-materials in preformed solid vulcanizates
used for sealing glazing and panels-specification. |
| ISO 4633 | Rubber seals-joint rings for water supply, drainage and sewerage
pipelines-specification for materials. |
| ISO 4635 | Rubber, vulcanized-preformed compression seals for use between
concrete motor way paving sections-specification for material. |
| ISO 5892 | Rubber building gaskets-materials for preformed solid vulcanized
structural gaskets-specification. |
| ISO 6447 | Rubber seals-joint rings used for gas supply pipes and fittings-
specification for material. |
| ISO 6589 | Joints in building-laboratory method of test for air permeability of
joints. |
| ISO 7389 | Building construction-jointing products-determination of elastic
recovery. |
| ISO 7390 | Building construction-jointing products-determination of resistance to
flow. |
| ISO 7727 | Joints in building-principles for jointing of building components-
accommodation of dimensional deviations during construction. |
| ISO 8339 | Building construction-jointing products-sealants-determination of
tensile properties. |
| ISO 8340 | Building construction-jointing products-sealants-determination of
tensile properties at maintained extension. |
| ISO 8394 | Building construction-jointing products-determination of extrudability
of one-component sealants. |
| ISO 9046 | Building construction-sealants-determination of adhesion/ cohesion
properties at constant temperature. |
| ISO 9047 | Building construction-sealants-determination of adhesion/ cohesion
properties at variable temperatures. |
| ISO 9631 | Rubber seals-joint rings for hot water supply pipelines up to $110^\circ\text{C}$
specifications for the material. |
| ISO 10563 | Building construction-sealants for joints-determination of change in
mass and volume. |
| ISO 10590 | Building construction-sealants-determination of adhesion/cohesion
properties at maintained extension after immersion in water. |
| ISO 10591 | Building construction-sealants-determination of adhesion/cohesion
properties after immersion in water. |
### **2.16.14 Glass and Glazing**
The applicable Standards for glass and glazing are listed below:
| Item | Description |
| ----------- | --------------------------------------------------------------------------------------------------------------- |
| ASTM C1036 | Standard Specification for Flat Glass. |
| ASTM C1048 | Standard Specification for Heat-Treated Flat Glass-Kind HS, Kind
FT Coated and Uncoated Glass. |
| ANSI Z 97.1 | Safety Performance Specifications and Methods of Tests for Transport Safety Glazing Materials Used in Building. |
| CPSC 16 CFR | Safety Standard for Architectural Glazing Materials. Part 1201A. |
## **2.17 Cgi Sheet Roofing and Walling**
Galvanized corrugated steel sheets conforming to BDS 868, Galvanized Corrugated Sheet Roof and Wall Coverings, may be used over structural framing for construction of roofs and walls. Requirements for various roofing materials including CGI sheet have been specified in Sec 2.13 above.
# Part V: Building Materials
Source: https://docs.sayed.app/bnbc/part-5-building-materials/index
Scope, definitions, and standards for building materials.
Part V sets scope and definitions for building materials, and lists the standards materials must conform to.
Scope and defined terms for this Part.
Standards for masonry, concrete, steel, timber, and other building materials.
# Chapter 1: Definitions and General Requirements
Source: https://docs.sayed.app/bnbc/part-6-structural-design/chapter-1-definitions-and-general-requirements
**Part VI Chapter 1 Definitions and General Requirements**
## **1.1 Introduction**
### **1.1.1 Scope**
The definitions providing meanings of different terms and general requirements for the structural design of buildings, structures, and components thereof are specified in this Chapter. These requirements shall apply to all buildings and structures or their components regulated by this Code. All anticipated loads required for structural design shall be determined in accordance with the provisions of Chapter 2. Design parameters required for the structural design of foundation elements shall conform to the provisions of Chapter 3. Design of structural members using various construction materials shall comply with the relevant provisions of Chapters 4 to 13. The FPS equivalents of the empirical expressions used throughout Part 6 are listed in Appendix A.
This Code shall govern in all matters pertaining to design, construction, and material properties wherever this Code is in conflict with requirements contained in other standards referenced in this Code. However, in special cases where the design of a structure or its components cannot be covered by the provisions of this Code, other relevant internationally accepted codes referred in this Code may be used.
### **1.1.2 Definitions**
The following definitions shall provide the meaning of certain terms used in this Chapter.
| BASE SHEAR | Total design lateral force or shear at the base of a
structure. |
| ------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BASIC WIND
SPEED | Three-second gust speed at 10 m above the mean ground
level in terrain Exposure-B defined in Sec 2.4.6 and
associated with an annual probability of occurrence of
0.02. |
| BEARING WALL
SYSTEM | A structural system without a complete vertical load
carrying space frame. |
| BRACED FRAME | An essentially vertical truss system of the concentric or
eccentric type which is provided to resist lateral forces. |
| BUILDING FRAME
SYSTEM | An essentially complete space frame which provides
support for loads. |
| CONCENTRIC
BRACED FRAME
(CBF) | A steel braced frame designed in conformance with Sec
10.20.13 or Sec 10.20.14. |
| COLLECTOR | A member or element used to transfer lateral forces from
a portion of a structure to the vertical elements of the
lateral force resisting elements. |
| DEAD LOAD | The load due to the weight of all permanent structural and
nonstructural components of a building or a structure,
such as walls, floors, roofs and fixed service equipment. |
| DIAPHRAGM | A horizontal or nearly horizontal system acting to transmit
lateral forces to the vertical resisting elements. The term
"diaphragm" includes horizontal bracing systems. |
| DUAL SYSTEM | A combination of Moment Resisting Frames and Shear
Walls or Braced Frames to resist lateral loads designed in
accordance with the criteria of Sec 1.3.2.4. |
| ECCENTRIC
BRACED FRAME
(EBF) | A steel braced frame designed in conformance with Sec
10.20.15. |
| HORIZONTAL
BRACING SYSTEM | A horizontal truss system that serves the same function as
a floor or roof diaphragm. |
| INTERMEDIATE
MOMENT FRAME
(IMF) | A concrete moment resisting frame designed in
accordancewith Sec 8.3.10. |
| LIVE LOAD | The load superimposed by the use and occupancy of a
building. |
| MOMENT
RESISTING FRAME |
A frame in which members and joints are capable of
resisting forces primarily by flexure. |
| ORDINARY
MOMENT FRAME
(OMF) | A moment resisting frame not meeting special detailing
requirements for ductile behaviour. |
| PRIMARY
FRAMING SYSTEM |
That part of the structural system assigned to resist lateral
forces. |
| SHEAR WALL | A wall designed to resist lateral forces parallel to the
plane of the wall (sometimes referred to as a vertical
diaphragm or a structural wall). |
| SLENDER
BUILDINGS AND
STRUCTURES | Buildings and structures having a height exceeding five
times the least horizontal dimension, or having a
fundamental natural frequency less than 1 Hz. For those
cases where the horizontal dimensions vary with height,
the least horizontal dimension at mid height shall be used. |
| SOFT STOREY | A soft storey is one in which the lateral stiffness is less
than 70 percent of that in the storey above or less than 80
percent of the average stiffness of the three storeys above. |
| SPACE FRAME | A three-dimensional structural system without bearing
walls composed of members interconnected so as to
function as a complete self-contained unit with or without
the aid of horizontal diaphragms or floor bracing systems. |
| SPECIAL MOMENT
FRAME (SMF) | A moment resisting frame specially detailed to provide
ductile behaviour complying with the requirements of
Chapter 8 or 10 for concrete or steel frames respectively. |
| SPECIAL
STRUCTURAL
SYSTEM | A structural system not listed in Table 6.1.3 and specially
designed to carry the lateral loads. (See Sec 1.3.2.5). |
| STOREY | The space between any two floor levels including the roof
of a building. Storey-x is the storey below level x. |
| STOREY SHEAR, | The summation of design lateral forces above the storey
under consideration. |
| STRENGTH | The usable capacity of an element or a member to resist
the load as prescribed in these provisions. |
| TERRAIN | The ground surface roughness condition when considering
the size and arrangement of obstructions to the wind. |
| THREE-SECOND | The highest average wind speed over a 3 second duration |
| GUST SPEED | at a height of 10 m. The three-second gust speed is
derived using Durst's model in terms of the mean wind
speed and turbulence intensity. |
| TOWER | A tall, slim vertical structure. |
| VERTICAL LOAD-
CARRYING FRAME |
A space frame designed to carry all vertical gravity loads. |
| WEAK STOREY | Storey in which the lateral strength is less than 80 percent
of that of the storey above. |
### **1.1.3 Symbols and Notation**
The following symbols and notation shall apply to the provisions of this Chapter:
* $D$ = Dead load on a member including self-weight and weight of components, materials and permanent equipment supported by the member
* $E$ = Earthquake load
* $F_i$ = Lateral force applied at level $-i$ of a building
* $h$ = Height of a building or a structure above ground level in metres
* $h_i, h_n, h_x$ = Height in metres above ground level to level $-i$, $-n$ or $-x$ respectively
* level $-i$ = $i^{th}$ level of a structure above the base; $i$ = 1 designates the first level above the base
* level $-n$ = Upper most level of a structure
* level $-x$ = $x^{th}$ level of a structure above the base; $x$ = 1 designates the first level above the base.
* $L$ = Live load due to intended use or occupancy
* $l$ = Span of a member or component.
* $M_x$ = Overturning moment at level $-x$
* $V$ = Total design lateral force or shear at the base
* $V_x$ = Storey shear at storey level $-x$
* $R$ = Response modification or reduction coefficient for structural system given in Table 6.2.19 for seismic design.
* $T$ = Fundamental period of vibration in seconds
* $W$ = Load due to wind pressure.
* $W'$ = Weight of an element or component
* $Z$ = Seismic zone coefficient given in Figure 6.2.24 or Table 6.2.14 or Table 6.2.15
* $\Delta$ = Storey lateral drift.
## **1.2 Basic Considerations**
### **1.2.1 General**
All buildings and structures shall be designed and constructed in conformance with the provisions of this Section. The buildings and portions thereof shall support all loads including dead load specified in this Chapter and elsewhere in this Code. Impact, fatigue and self-straining forces shall be considered where these forces occur.
### **1.2.2 Buildings and Structures**
A structure shall ordinarily be described as an assemblage of framing members and components arranged to support both gravity and lateral forces. Structures may be classified as building and non-building structures. Structures that enclose a space and are used for various occupancies shall be called buildings or building structures. Structures other than buildings, such as water tanks, bridges, communication towers, chimneys etc., shall be called non-building structures. When used in conjunction with the word building(s), the word structure(s) shall mean non-building structures, e.g. 'buildings and structures' or 'buildings or structures'. Otherwise the word 'structures' shall include both buildings and non-building structures.
### **1.2.3 Building and Structure Occupancy Categories**
Buildings and other structures shall be classified, based on the nature of occupancy, according to Table 6.1.1 for the purposes of applying flood, surge, wind and earthquake provisions. The occupancy categories range from I to IV, where Occupancy Category I represents buildings and other structures with a low hazard to human life in the event of failure and Occupancy Category IV represents essential facilities. Each building or other structure shall be assigned to the highest applicable occupancy category or categories. Assignment of the same structure to multiple occupancy categories based on use and the type of load condition being evaluated (e.g., wind or seismic) shall be permissible.
When buildings or other structures have multiple uses (occupancies), the relationship between the uses of various parts of the building or other structure and the independence of the structural systems for those various parts shall be examined. The classification for each independent structural system of a multiple-use building or other structure shall be that of the highest usage group in any part of the building or other structure that is dependent on that basic structural system.
**Table 6.1.1: Occupancy Category of Buildings and other Structures for Flood, Surge, Wind and Earthquake Loads.**
| Nature of Occupancy | Occupancy Category |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------ |
| Buildings and other structures that represent a low hazard to human life in the event of failure, including, but not limited to:
- Agricultural facilities
- Certain temporary facilities
- Minor storage facilities | I |
| All buildings and other structures except those listed in Occupancy Categories I, III and IV | II |
| Buildings and other structures that represent a substantial hazard to human life in the event of failure, including, but not limited to:
- Buildings and other structures where more than 300 people congregate in one area
- Buildings and other structures with day care facilities with a capacity greater than 150
- Buildings and other structures with elementary school or secondary school facilities with a capacity greater than 250
- Buildings and other structures with a capacity greater than 500 for colleges or adult education facilities
- Healthcare facilities with a capacity of 50 or more resident patients, but not having surgery or emergency treatment facilities
- Jails and detention facilities
Buildings and other structures, not included in Occupancy Category IV, with potential to cause a substantial economic impact and/or mass disruption of day-to-day civilian life in the event of failure, including, but not limited to:
- Power generating stations*a*
- Water treatment facilities
- Sewage treatment facilities
- Telecommunication centers
Buildings and other structures not included in Occupancy Category IV (including, but not limited to, facilities that manufacture, process, handle, store, use, or dispose of such substances as hazardous fuels, hazardous chemicals, hazardous waste, or explosives) containing sufficient quantities of toxic or explosive substances to be dangerous to the public if released. | III |
| Buildings and other structures designated as essential facilities, including, but not limited to:
- Hospitals and other healthcare facilities having surgery or emergency treatment facilities
- Fire, rescue, ambulance, and police stations and emergency vehicle garages
- Designated earthquake, hurricane, or other emergency shelters
- Designated emergency preparedness, communication, and operation centers and other facilities required for emergency response
- Power generating stations and other public utility facilities required in an emergency
- Ancillary structures (including, but not limited to, communication towers, fuel storage tanks, cooling towers, electrical substation structures, fire water storage tanks or other structures housing or supporting water, or other fire-suppression material or equipment) required for operation of Occupancy Category IV structures during an emergency
- Aviation control towers, air traffic control centers, and emergency aircraft hangars
- Community water storage facilities and pump structures required to maintain water pressure for fire suppression
- Buildings and other structures having critical national defense functions
Buildings and other structures (including, but not limited to, facilities that manufacture, process, handle, store, use, or dispose of such substances as hazardous fuels, hazardous chemicals, or hazardous waste) containing highly toxic substances where the quantity of the material exceeds a threshold quantity established by the authority having jurisdiction. | IV |
*a* Cogeneration power plants that do not supply power on the national grid shall be designated Occupancy Category II
### **1.2.4 Safety**
Buildings, structures and components thereof, shall be designed and constructed to support all loads, including dead loads, without exceeding the allowable stresses or specified strengths (under applicable factored loads) for the materials of construction in the structural members and connections.
### **1.2.5 Serviceability**
Structural framing systems and components shall be designed with adequate stiffness to have deflections, vibration, or any other deformations within the serviceability limit of building or structure. The deflections of structural members shall not exceed the more restrictive of the limitations provided in Chapters 2 through 13 or that permitted by Table 6.1.2 or the notes that follow. For wind and earthquake loading, story drift and sway shall be limited in accordance with the provisions of Sec 1.5.6. In checking the serviceability, the load combinations and provisions of Sec 2.7.5 shall be followed.
**Table 6.1.2: Deflection Limits****a, b, c, h** **(Except earthquake load)**
| Construction | $L$ | $W^f$ | $D^g + L^d$ |
| -------------------------------------- | ------- | ------- | ----------- |
| Roof members:*e* | | | |
| Supporting plaster ceiling | $l/360$ | $l/360$ | $l/240$ |
| Supporting non-plaster ceiling | $l/240$ | $l/240$ | $l/180$ |
| Not supporting ceiling | $l/180$ | $l/180$ | $l/120$ |
| Floor members | $l/360$ | — | $l/240$ |
| Exterior walls and interior partitions | | | |
| With brittle finishes | — | $l/240$ | — |
| With flexible finishes | — | $l/120$ | — |
| Farm buildings | — | — | $l/180$ |
| Greenhouses | — | — | $l/120$ |
Where, $l$, $L$, $W$ and $D$ stands for span of the member under consideration, live load, wind load and dead load respectively.
Notes:
* *a.* For structural roofing and siding made of formed metal sheets, the total load deflection shall not exceed $l/60$. For secondary roof structural members supporting formed metal roofing, the live load deflection shall not exceed $l/150$. For secondary wall members supporting formed metal siding, the design wind load deflection shall not exceed $l/90$. For roofs, this exception only applies when the metal sheets have no roof covering.
* *b.* Interior partitions not exceeding 2 m in height and flexible, folding and portable partitions are not governed by the provisions of this Section.
* *c.* For cantilever members, $l$ shall be taken as twice the length of the cantilever.
* *d.* For wood structural members having a moisture content of less than 16% at time of installation and used under dry conditions, the deflection resulting from $L + 0.5D$ is permitted to be substituted for the deflection resulting from $L + D$.
* *e.* The above deflections do not ensure against ponding. Roofs that do not have sufficient slope or camber to assure adequate drainage shall be investigated for ponding. See Sec 1.6.5 for rain and ponding requirements.
* *f.* The wind load is permitted to be taken as 0.7 times the “component and cladding” loads for the purpose of determining deflection limits herein.
* *g.* Deflection due to dead load shall include both instantaneous and long term effects.
* *h.* For aluminum structural members or aluminum panels used in skylights and sloped glazing framing, roofs or walls of sunroom additions or patio covers, not supporting edge of glass or aluminum sandwich panels, the total load deflection shall not exceed $l/60$. For continuous aluminum structural members supporting edge of glass, the total load deflection shall not exceed $l/175$ for each glass lite or $l/60$ for the entire length of the member, whichever is more stringent. For aluminum sandwich panels used in roofs or walls of sunroom additions or patio covers, the total load deflection shall not exceed $l/120$.
### **1.2.6 Rationality**
Structural systems and components thereof shall be analyzed, designed and constructed based on rational methods which shall include, but not be limited to the provisions of Sec 1.2.7.
### **1.2.7 Analysis**
Analysis of the structural systems shall be made for determining the load effects on the resisting elements and connections, based on well-established principles of mechanics taking equilibrium, geometric compatibility and both short and long term properties of the construction materials into account and incorporating the following:
#### 1.2.7.1 Mathematical model
A mathematical model of the physical structure shall represent the spatial distribution of stiffness and other properties of the structure which is adequate to provide a complete load path capable of transferring all loads and forces from their points of origin to the load-resisting elements for obtaining various load effects. For dynamic analysis, mathematical model shall also incorporate the appropriately distributed mass and damping properties of the structure adequate for the determination of the significant features of its dynamic response. All buildings and structures shall be thus analyzed preferably using a three dimensional computerized model incorporating these features of mathematical model. It is essential to use three dimensional computer model to represent a structure having irregular plan configuration as mentioned in Sec 1.3.4.2 and having rigid or semirigid floor and roof diaphragms. Requirements for two-dimensional model and three dimensional models for earthquake analysis are described in Sections 2.5.11 to 2.5.14.
#### 1.2.7.2 Loads and forces
All prescribed loads and forces to be supported by the structural systems shall be determined in accordance with the applicable provisions of this Chapter and Chapter 2. Loads shall be applied on the mathematical model specified in Sec. 1.2.7.1 at appropriate spatial locations and along desired directions.
#### 1.2.7.3 Soil-structure interaction
Soil-structure interaction effects, where required, shall be included in the analysis by appropriately including the properly substantiated properties of soil into the mathematical model specified in Sec. 1.2.7.1 above.
### **1.2.8 Distribution of Horizontal Shear**
The total lateral force shall be distributed to the various elements of the lateral forceresisting system in proportion to their rigidities considering the rigidity of the horizontal bracing systems or diaphragms.
### **1.2.9 Horizontal Torsional Moments**
Structural systems and components shall be designed to sustain additional forces resulting from torsion due to eccentricity between the centre of application of the lateral forces and the centre of rigidity of the lateral force resisting system. Forces shall not be decreased due to torsional effects. For accidental torsion effects on seismic forces, requirements shall conform to Sec 2.5.7.6.
### **1.2.10 Stability Against Overturning and Sliding**
Every building or structure shall be designed to resist the overturning and sliding effects caused by the lateral forces specified in this Chapter.
### **1.2.11 Anchorage**
Anchorage of the roof to wall and columns, and of walls and columns to foundations, shall be provided to resist the uplift and sliding forces resulting from the application of the prescribed loads. Additional requirements for masonry or concrete walls shall be those given in Sec 1.7.3.6.
### **1.2.12 General Structural Integrity**
Buildings and structural systems shall possess general structural integrity that is the ability to sustain local damage caused due to misuse or accidental overloading, with the structure as a whole remaining stable and not being damaged to an extent disproportionate to the original local damage.
### **1.2.13 Proportioning of Structural Elements**
Structural elements, components and connections shall be proportioned and detailed based on the design methods provided in the subsequent Chapters for various materials of construction, such as reinforced concrete, masonry, steel etc. to resist various load effects obtained from a rational analysis of the structural system.
### **1.2.14 Walls and Framing**
Walls and structural framing shall be erected true to plumb in accordance with the design. Interior walls, permanent partitions and temporary partitions exceeding 1.8 m of height shall be designed to resist all loads to which they are subjected. If not otherwise specified elsewhere in this Code, walls shall be designed for a minimum load of 0.25 kN/m2 applied perpendicular to the wall surfaces. The deflection of such walls under a load of 0.25 kN/m2 shall not exceed $\frac{1}{240}$ of the span for walls with brittle finishes and $\frac{1}{120}$ of the span for walls with flexible finishes. However, flexible, folding or portable partitions shall not be required to meet the above load and deflection criteria, but shall be anchored to the supporting structure.
### **1.2.15 Additions to Existing Structures**
When an existing building or structure is extended or otherwise altered, all portions thereof affected by such cause shall be strengthened, if necessary, to comply with the safety and serviceability requirements provided in Sections 1.2.4 and 1.2.5 respectively.
### **1.2.16 Phased Construction**
When a building or structure is planned or anticipated to undergo phased construction, structural members therein shall be investigated and designed for any additional stresses arising due to such construction.
### **1.2.17 Load Combinations and Stress Increase**
Every building, structure, foundation or components thereof shall be designed to sustain, within the allowable stress or specified strength (under factored load), the most unfavourable effects resulting from various combinations of loads specified in Sec 2.7. Except otherwise permitted or restricted by any other Sections of this Code, maximum increase in the allowable stress shall be 33% when allowable or working stress method of design is followed. For soil stresses due to foundation loads, load combinations and stress increase specified in Sec 2.7.2 for allowable stress design method shall be used.
## **1.3 Structural Systems**
### **1.3.1 General**
Every structure shall have one of the basic structural systems specified in Sec 1.3.2 or a combination thereof. The structural configuration shall be as specified in Sec 1.3.4 with the limitations imposed in Sec 2.5.5.4.
### **1.3.2 Basic Structural Systems**
Structural systems for buildings and other structures shall be designated as one of the types A to G listed in Table 6.1.3. Each type is again classified as shown in the Table by the types of vertical elements used to resist lateral forces. A brief description of different structural systems are presented in following sub-sections.
#### 1.3.2.1 Bearing wall system
A structural system having bearing walls/bracing systems without a complete vertical load carrying frame to support gravity loads. Resistance to lateral loads is provided by shear walls or braced frames.
#### 1.3.2.2 Building frame system
A structural system with an essentially complete space frame providing support for gravity loads. Resistance to lateral loads is provided by shear walls or braced frames separately.
#### 1.3.2.3 Moment resisting frame system
A structural system with an essentially complete space frame providing support for gravity loads. Moment resisting frames also provide resistance to lateral load primarily by flexural action of members, and may be classified as one of the following types:
* (a) Special Moment Frames (SMF)
* (b) Intermediate Moment Frames (IMF)
* (c) Ordinary Moment Frames (OMF).
The framing system, IMF and SMF shall have special detailing to provide ductile behaviour conforming to the provisions of Sections 8.3 and 10.20 of Part 6 for concrete and steel structures respectively. OMF need not conform to these special ductility requirements of Chapter 8 or 10.
**Table 6.1.3: Basic Structural Systems**
* A. BEARING WALL SYSTEMS (no frame)
1. Special reinforced concrete shear walls
2. Ordinary reinforced concrete shear walls
3. Ordinary reinforced masonry shear walls
4. Ordinary plain masonry shear walls
* B. BUILDING FRAME SYSTEMS (with bracing or shear wall)
1. Steel eccentrically braced frames, moment resisting connections at columns away from links
2. Steel eccentrically braced frames, non-moment-resisting, connections at columns away from links
3. Special steel concentrically braced frames
4. Ordinary steel concentrically braced frames
5. Special reinforced concrete shear walls
6. Ordinary reinforced concrete shear walls
7. Ordinary reinforced masonry shear walls
8. Ordinary plain masonry shear walls
* C. MOMENT RESISTING FRAME SYSTEMS (no shear wall)
1. Special steel moment frames
2. Intermediate steel moment frames
3. Ordinary steel moment frames
4. Special reinforced concrete moment frames
5. Intermediate reinforced concrete moment frames
6. Ordinary reinforced concrete moment frames
* D. DUAL SYSTEMS: SPECIAL MOMENT FRAMES CAPABLE OF RESISTING AT LEAST 25% OF PRESCRIBED SEISMIC FORCES (with bracing or shear wall)
1. Steel eccentrically braced frames
2. Special steel concentrically braced frames
3. Special reinforced concrete shear walls
4. Ordinary reinforced concrete shear walls
* E. DUAL SYSTEMS: INTERMEDIATE MOMENT FRAMES CAPABLE OF RESISTING AT LEAST 25% OF PRESCRIBED SEISMIC FORCES (with bracing or shear wall)
1. Special steel concentrically braced **f** rames
2. Special reinforced concrete shear walls
3. Ordinary reinforced masonry shear walls
4. Ordinary reinforced concrete shear walls
* F. DUAL SHEAR WALL-FRAME SYSTEM: ORDINARY REINFORCED CONCRETE MOMENT FRAMES AND ORDINARY REINFORCED CONCRETE SHEAR WALLS
* G. STEEL SYSTEMS NOT SPECIFICALLY DETAILED FOR SEISMIC RESISTANCE
#### 1.3.2.4 Dual system
A structural system having a combination of the following framing systems:
* (a) Moment resisting frames (SMF, IMF or steel OMF), and
* (b) Shear walls or braced frames.
The two systems specified in (a) and (b) above shall be designed to resist the total lateral force in proportion to their relative rigidities considering the interaction of the dual system at all levels. However, the moment resisting frames shall be capable of resisting at least 25% of the applicable total seismic lateral force, even when wind or any other lateral force governs the design.
#### 1.3.2.5 Special structural system
A structural system not defined above nor listed in Table 6.1.3 and specially designed to carry the lateral loads, such as tube-in-tube, bundled tube, etc.
#### 1.3.2.6 Non-building structural system
A structural system used for purposes other than in buildings and conforming to Sections 1.5.4.8, 1.5.4.9, 2.4 and 2.5 of Part 6.
### **1.3.3 Combination of Structural Systems**
When different structural systems of Sec 1.3.2 are combined for incorporation into the same structure, design of the combined seismic force resisting system shall conform to the provisions of Sec 2.5.5.5.
### **1.3.4 Structural Configurations**
Based on the structural configuration, each structure shall be designated as a regular or irregular structure as defined below:
#### 1.3.4.1 Regular structures
Regular structures have no significant physical discontinuities or irregularities in plan or vertical configuration or in their lateral force resisting systems. Typical features causing irregularity are described in Sec 1.3.4.2.
#### 1.3.4.2 Irregular structures
Irregular structures have either vertical irregularity or plan irregularity or both in their structural configurations or lateral force resisting systems.
##### 1.3.4.2.1 Vertical irregularity
Structures having one or more of the irregular features listed in Table 6.1.4 shall be designated as having a vertical irregularity.
##### 1.3.4.2.2 Plan irregularity
Structures having one or more of the irregular features listed in Table 6.1.5 shall be designated as having a plan irregularity.
**Table 6.1.4: Vertical Irregularities of Structures**
| **Vertical** | **Definition** | **Reference** |
| --------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------- |
| **Irregularity**
**Type** | | **Section** |
| I | **a. Stiffness Irregularity (Soft Storey):**
Soft storey is one in which the lateral stiffness is less than 70
percent of that in the storey above or less than 80 percent of
the average stiffness of the three storeys above.
**b. Stiffness Irregularity (Extreme Soft Storey):**
Extreme soft storey irregularity is defined to exist where there
is a story in which the lateral stiffness is less than 60% of that
in the story above or less than 70% of the average stiffness of
the three stories above. | 1.7.3.8,
2.5.5 to
2.5.14
and
2.5.17 |
| II | **Mass Irregularity:**
Mass irregularity shall be considered to exist where the effective
mass of any storey is more than 150 percent of the effective
mass of an adjacent storey. A roof which is lighter than the floor
below need not be considered. | 2.5.5 to
2.5.14 |
| III | **Vertical Geometric Irregularity:**
Vertical geometric irregularity shall be considered to exist
where horizontal dimension of the lateral force-resisting system
in any storey is more than 130 percent of that in an adjacent
storey, one-storey penthouses need not be considered. | 2.5.5 to
2.5.14 |
| IV | **In-Plane Discontinuity in Vertical Lateral Force-Resisting**
**Element:**
An in-plane offset of the lateral load-resisting elements greater
than the length of those elements. | 1.7.3.8,
2.5.5 to
2.5.14 |
| Va | **Discontinuity in Capacity (Weak Storey):**
A weak storey is one in which the storey strength is less than 80
percent of that in the storey above. The storey strength is the
total strength of all seismic-resisting elements sharing the storey
shear for the direction under consideration. | 2.5.5 to
2.5.14
and
2.5.17 |
| Vb | **Extreme Discontinuity in Capacity (Very Weak Storey):**
A very weak storey is one in which the storey strength is less
than 65 percent of that in the storey above. | 2.5.5 to
2.5.14
and
2.5.17 |
| **Table 6.1.5: Plan (Horizontal) Irregularities of Structures** | | |
| **Plan** | **Definition** | **Reference** |
| ------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------- |
| **Irregularity**
**Type** | | **Section** |
| I | **Torsional Irregularity (to be considered when diaphragms**
**are not flexible):**
a. Torsional irregularity shall be considered to exist when the
maximum storey drift, computed including accidental
torsion, at one end of the structure is more than 1.2 times
the average of the storey drifts at the two ends of the
structure.
b. Extreme Torsional Irregularity is defined to exist where the
maximum story drift, computed including accidental
torsion, at one end of the structure transverse to an axis is
more than 1.4 times the average of the story drifts at the
two ends of the structure. Extreme torsional irregularity
requirements in the reference sections apply only to
structures in which the diaphragms are rigid or semirigid. |
1.7.3.8,
2.5.5 to
2.5.14 |
| II | **Reentrant Corners:**
Plan configurations of a structure and its lateral force-resisting
system contain reentrant corners, where both projections of the
structure beyond a reentrant corner are greater than 15 percent
of the plan dimension of the structure in the given direction. |
1.7.3.8,
2.5.5 to
2.5.14 |
| III | **Diaphragm Discontinuity:**
Diaphragms with abrupt discontinuities or variations in
stiffness, including those having cutout or open areas greater
than 50 percent of the gross enclosed area of the diaphragm, or
changes in effective diaphragm stiffness of more than 50
percent from one storey to the next. |
1.7.3.8,
2.5.5 to
2.5.14 |
| IV | **Out-of-plane Offsets:**
Discontinuities in a lateral force path, such as out-of-plane
offsets of the vertical elements. |
1.7.3.8,
2.5.5 to
2.5.14 |
| V | **Nonparallel Systems:**
The vertical lateral load-resisting elements are not parallel to or
symmetric about the major orthogonal axes of the lateral force-
resisting system. |
2.5.5 to
2.5.15 |
## **1.4 Design For Gravity Loads**
### **1.4.1 General**
Design of buildings and components thereof for gravity loads shall conform to the requirements of this Section. Gravity loads, such as dead load and live loads applied at the floors or roof of a building shall be determined in accordance with the provisions of Chapter 2 of this Part.
### **1.4.2 Floor Design**
Floor slabs and decks shall be designed for the full dead and live loads as specified in Sections 2.2 and 2.3 respectively. Floor supporting elements such as beams, joists, columns etc. shall be designed for the full dead load and the appropriately reduced live loads set forth by the provisions of Sec 2.3.13. Design of floor elements shall also conform to the following provisions:
* (a) Uniformly Distributed Loads: Where uniform floor loads are involved, consideration may be limited to full dead load on all spans in combination with full live load on adjacent spans and on alternate spans to determine the most unfavourable effect of stresses in the member concerned.
* (b) Concentrated Loads: Provision shall be made in designing floors for a concentrated load as set forth in Sec 2.3.5 applied at a location wherever this load acting upon an otherwise unloaded floor would produce stresses greater than those caused by the uniform load required therefore.
* (c) Partition Loads: Loads due to permanent partitions shall be treated as a dead load applied over the floor as a uniform line load having intensity equal to the weight per metre run of the partitions as specified in Sec 2.2.5. Loads for light movable partitions shall be determined in accordance with the provisions of Sec 2.3.6.
* (d) Design of Members: Floor members, such as slabs or decks, beams, joists etc. shall be designed to sustain the worst effect of the dead plus live loads or any other load combinations as specified in Sec 2.7. Where floors are used as diaphragms to transmit lateral loads between various resisting elements, those loads shall be determined following the provisions of Sec 1.7.3.8. Detailed design of the floor elements shall be performed using the procedures provided in Chapters 4 to 13 of Part 6 for various construction materials.
* (e) Floors and associated structural members shall have adequate strength and stiffness to prevent undesirable vibration due to human activity (e.g walking, dancing, jumping, sporting activities etc.) or vibration caused by machines which causes discomfort to the occupants and which is detrimental to the safety, integrity and durability of the structure.
### **1.4.3 Roof Design**
Roofs and their supporting elements shall be designed to sustain, within their allowable stresses or specified strength limits, all dead loads and live loads as set out by the provisions of Sections 2.2 and 2.3 respectively. Design of roof members shall also conform to the following requirements:
* (a) Application of Loads: When uniformly distributed loads are considered for the design of continuous structural members, load including full dead loads on all spans in combination with full live loads on adjacent spans and on alternate span, shall be investigated to determine the worst effects of loading. Concentrated roof live loads and special roof live loads, where applicable, shall also be considered in design.
* (b) Unbalanced Loading: Effects due to unbalanced loads shall be considered in the design of roof members and connections where such loading will result in more critical stresses. Trusses and arches shall be designed to resist the stresses caused by uniform live loads on one half of the span if such loading results in reverse stresses, or stresses greater in any portion than the stresses produced by this unit live load when applied upon the entire span.
* (c) Rain Loads: Roofs, where ponding of rain water is anticipated due to blockage of roof drains, excessive deflection or insufficient slopes, shall be designed to support such loads. Loads on roofs due to rain shall be determined in accordance with the provisions of Sec 2.6.2. In addition to the dead load of the roof, either the roof live load or the rain load, whichever is of higher intensity, shall be considered in design.
### **1.4.4 Reduction of Live Loads**
The design live loads specified in Sec 2.3, may be reduced to appropriate values as permitted by the provisions of Sections 2.3.13 and 2.3.14.
### **1.4.5 Posting of Live Loads**
In every building, of which the floors or parts thereof have a design live load of 3.5 kN/m2 or more, and which are used as library stack room, file room, parking garage, machine or plant room, or used for industrial or storage purposes, the owner of the building shall ensure that the live loads for which such space has been designed, are posted on durable metal plates as shown in Figure 6.1.1, securely affixed in a conspicuous place in each space to which they relate. If such plates are lost, removed, or defaced, owner shall be responsible to have them replaced.
### **1.4.6 Restrictions on Loading**
The building owner shall ensure that the live load for which a floor or roof is or has been designed, will not be exceeded during its use.
![Sample live load sign showing floor load capacity plate format and mounting details]()
### **1.4.7 Special Considerations**
In the absence of actual dead and live load data, the minimum values of these loads shall be those specified in Sections 2.2 and 2.3. In addition, special consideration shall be given to the following aspects of loading and due allowances shall be made in design if occurrence of such loading is anticipated after construction of a building:
* (a) Increase in Dead Load: Actual thickness of the concrete slabs or other members may become larger than the designed thickness due to movements or deflections of the formwork during construction.
* (b) Future Installations: Changes in the numbers, types and positions of partitions and other installations may increase actual load on the floors of a building.
* (c) Occupancy Changes: Increase in live loads due to changes of occupancy involving loads heavier than that being designed for.
### **1.4.8 Deflection and Camber**
Structural systems and members thereof shall be designed to have adequate stiffness to limit deflections. The deflections of structural members shall not exceed the more restrictive of the limitations of Chapters 2 to 13 of this Part or that permitted by Table 6.1.2.or provisions of Sec 1.2.5 of this Chapter. In calculating deflections due to gravity loads, long term effects (e.g. creep, shrinkage or stress relaxation) should also be considered.
## **1.5 Design For Lateral Loads**
### **1.5.1 General**
Every building, structure or portions thereof shall be designed to resist the lateral load effects, such as those due to wind or earthquake forces, in compliance with the requirements prescribed in this Section.
### **1.5.2 Selection of Lateral Force for Design**
Any of the lateral loads prescribed in Chapter 2, considered either alone or in combination with other forces, whichever produces the most critical effect, shall govern the design. However, the structural detailing requirements shall comply with those prescribed in Sec 1.7 of this Chapter. When a dual structural system is used to resist lateral loads, design shall also conform to Sec 1.3.2.4 of this Chapter.
### **1.5.3 Design for Wind Load**
Design of buildings and their components to resist wind induced forces shall comply with the following requirements:
#### 1.5.3.1 Direction of wind
Structural design for wind forces shall be based on assumption that wind may blow from any horizontal direction.
#### 1.5.3.2 Design considerations
Design wind load on the primary framing systems and components of a building or structure shall be determined on the basis of the procedures provided in Sec 2.4 Chapter 2 Part 6 considering the basic wind speed, shape and size of the building, and the terrain exposure condition of the site. For slender buildings and structures, dynamic response characteristics, such as fundamental natural frequency, shall be determined to estimate gust response coefficient. Load effects, such as forces, moments, and deflections etc. on various components of building due to wind shall be determined from static analysis of the structure as specified in Sec 1.2.7.1 of this Chapter.
#### 1.5.3.3 Shielding effect
Reductions in wind pressure on buildings and structures due to apparent direct shielding effects of the up wind obstructions, such as man-made constructions or natural terrain features, shall not be permitted.
#### 1.5.3.4 Dynamic effects
Dynamic wind forces such as that from along-wind vibrations caused by the dynamic wind-structure interaction effects, as set forth by the provisions of Sec 2.4.8 Chapter 2 Part 6, shall be considered in the design of regular shaped slender buildings. For other dynamic effects such as cross-wind or torsional responses as may be experienced by buildings or structures having unusual geometrical shapes (i.e. vertical or plan irregularities listed in Tables 6.1.4 and 6.1.5), response characteristics, or site locations, structural design shall be made based on the information obtained either from other reliable references or from wind-tunnel test specified in Sec 1.5.3.5 below, complying with the other requirements of this Section.
#### 1.5.3.5 Wind tunnel test
Properly conducted wind-tunnel tests shall be required for those buildings or structures having unusual geometric shapes, response characteristics, or site locations for which cross-wind response such as vortex shedding, galloping etc. warrant special consideration, and for which no reliable literature for the determination of such effects is available. This test is also recommended for those buildings or structures for which more accurate wind-loading information is desired than those given in this Section and in Sec 2.4. Tests for the determination of mean and fluctuating components of forces and pressures shall be considered to be properly conducted only if the following requirements are satisfied:
* (a) The natural wind has been modelled to account for the variation of wind speed with height,
* (b) The intensity of the longitudinal components of turbulence has been taken into consideration in the model,
* (c) The geometric scale of the structural model is not more than three times the geometric scale of the longitudinal component of turbulence,
* (d) The response characteristics of the wind tunnel instrumentation are consistent with the measurements to be made, and
* (e) The Reynolds number is taken into consideration when determining forces and pressures on the structural elements.
Tests for the purpose of determining the dynamic response of a structure shall be considered to be properly conducted only if requirements (a) through (e) above are fulfilled and, in addition, the structural model is scaled with due consideration to length, distribution of mass, stiffness and damping of the structure.
#### 1.5.3.6 Wind loads during construction
Buildings, structures and portions thereof under construction, and construction structures such as formwork, staging etc. shall be provided with adequate temporary bracings or other lateral supports to resist the wind load on them during the erection and construction phase.
#### 1.5.3.7 Masonry construction in high-wind regions
Design and construction of masonry structures in high-wind regions shall conform to the requirements of relevant Sections of Chapter 7 Part 6.
#### 1.5.3.8 Height limits
Unless otherwise specified elsewhere in this Code, no height limits shall be imposed, in general, on the design and construction of buildings or structures to resist wind induced forces.
### **1.5.4 Design for Earthquake Forces**
Design of structures and components thereof to resist the effects of earthquake forces shall comply with the requirements of this Section.
#### 1.5.4.1 Basic design consideration
For the purpose of earthquake resistant design, each structure shall be placed in one of the seismic zones as given in Sec 2.5.4.2 and assigned with a structure importance category as set forth in Sec 2.5.5.1. The seismic forces on structures shall be determined considering seismic zoning, site soil characteristics, structure importance, structural systems and configurations, height and dynamic properties of the structure as provided in Sec 2.5. The structural system and configuration types for a building or a structure shall be determined in accordance with the provisions of Sec 2.5.5.4. Other seismic design requirements shall be those specified in this Section.
#### 1.5.4.2 Requirements for directional effects
The directions of application of seismic forces used in the design shall be those which will produce the most critical load effects. Earthquake forces act in both principal directions of the building simultaneously. Design provisions for considering earthquake component in orthogonal directions have been provided in Sec 2.5.13.1.
#### 1.5.4.3 Structural system and configuration requirements
Seismic design provisions impose the following limitations on the use of structural systems and configurations:
* (a) The structural system used shall satisfy requirements of the Seismic Design Category (defined in Sec. 2.5.5.2) and height limitations given in Sec 2.5.5.4.
* (b) Structures assigned to Seismic Design Category D having vertical irregularity Type Vb of Table 6.1.4 shall not be permitted. Structures with such vertical irregularity may be permitted for Seismic Design Category B or C but shall not be over two stories or 9 m in height.
* (c) Structures having irregular features described in Table 1.3.2 or Table 1.3.3 shall be designed in compliance with the additional requirements of the Sections referenced in these Tables.
* (d) Special Structural Systems defined in Sec 1.3.2.5 may be permitted if it can be demonstrated by analytical and test data to be equivalent, with regard to dynamic characteristics, lateral force resistance and energy absorption, to one of the structural systems listed in Table 6.2.19, for obtaining an equivalent R and Cd value for seismic design.
#### 1.5.4.4 Methods of analysis
Earthquake forces and their effects on various structural elements shall be determined by using either a static analysis method or a dynamic analysis method whichever is applicable based on the limitations set forth in Sections 2.5.5 to 2.5.12 and conforming to Sec 1.2.7.
#### 1.5.4.5 Minimum design seismic force
The minimum design seismic forces shall be those determined in accordance with the Sections 2.5.5 to 2.5.14 whichever is applicable.
#### 1.5.4.6 Distribution of seismic forces
The total lateral seismic forces and moments shall be distributed among various resisting elements at any level and along the vertical direction of a building or structure in accordance with the provisions of Sections 2.5.5 to 2.5.12 as appropriate.
#### 1.5.4.7 Vertical components of seismic forces
Design provisions for considering vertical component of earthquake ground motion is given in Sec 2.5.13.2
#### 1.5.4.8 Height limits
Height limitations for different structural systems are given in Table 6.2.19 of Sec 2.5.3.4 Chapter 2 Part 6 of this Code as a function of seismic design category.
#### 1.5.4.9 Non-building structures
Seismic lateral force on non-building structures shall be determined in accordance with the provisions of ASCE 7: Minimum Design Loads for Buildings and other Structures. However, provisions of ASCE 7 may be simplified, consistent with the provisions of Sec 2.5 Part 6 of this Code. Other design requirements shall be those provided in this Chapter.
### **1.5.5 Overturning Requirements**
Every structure shall be designed to resist the overturning effects caused by wind or earthquake forces specified in Sections 2.4 and 2.5 respectively as well other lateral forces like earth pressure, tidal surge etc. The overturning moment $M_x$ at any storey level-$x$ of a building shall be determined as:
$$
M_x = \sum_{i=1}^{n} F_i(h_i - h_x) \tag{6.1.1}
$$
Where,
$h_i, h_x, h_n$ = Height in metres at level-$i$, -$x$ or -$n$ respectively.
$F_i$ = Lateral force applied at level-$i$, $i$ = 1 to $n$.
At any level, the increment of overturning moment shall be distributed to the various resisting elements in the same manner as the distribution of horizontal shear prescribed in Sec 2.5.7.5. Overturning effects on every element shall be carried down to the foundation level.
### **1.5.6 Drift and Building Separation**
#### 1.5.6.1 Storey drift limitation
Storey drift is the horizontal displacement of one level of a building or structure relative to the level above or below due to the design gravity (dead and live loads) or lateral forces (e.g. wind and earthquake loads). Calculated storey drift shall include both translational and torsional deflections and conform to the following requirements:
* (a) Storey drift, $\Delta$, for loads other than earthquake loads, shall be limited as follows:
$\Delta \leq 0.005h$ for $T < 0.7$ second
$\Delta \leq 0.004h$ for $T \geq 0.7$ second
$\Delta \leq 0.0025h$ for unreinforced masonry structures.
Where, $h$ = height of floor. The period $T$ used in this calculation shall be the same as that used for determining the base shear in Sec 2.5.7.2.
* (b) The drift limits set out in (a) above may be exceeded where it can be demonstrated that greater drift can be tolerated by both structural and nonstructural elements without affecting life safety.
* (c) For earthquake loads, the story drift, $\Delta$ shall be limited in accordance with the limits set forth in Sec 2.5.14.1
#### 1.5.6.2 Sway limitation
The overall sway (horizontal deflection) at the top level of the building or structure due to wind loading shall not exceed $\frac{1}{500}$ times the total height of the building above ground, in accordance with Sec 2.7.5.
### **1.5.7 Building Separation**
All components of a structure shall be designed and constructed to act as an integral unit unless they are separated structurally by a distance sufficient to avoid contact under the most unfavorable condition of deflections due to lateral loads. For seismic loads, design guidelines are given in Sec 2.5.14.3.
### **1.5.8 P-Delta Effects**
The resulting member forces and moments and the storey drifts induced by P-Delta effects need not be considered when the stability coefficient ($\theta$) remains within 0.10. This coefficient (described in Sec 2.5.7.9) may be evaluated for any storey as the product of the total vertical dead and live loads above the storey and the lateral drift in that storey divided by the product of the storey shear in that storey and the height of that storey.
### **1.5.9 Uplift Effects**
Uplift effects caused due to lateral loads shall be considered in design. When allowable (working) stress method is used for design, dead loads used to reduce uplift shall be multiplied by a factor of 0.85.
## **1.6 Design For Miscellaneous Loads**
### **1.6.1 General**
Buildings, structures and components thereof, when subject to loads other than dead, live, wind and earthquake loads, shall be designed in accordance with the provisions of this Section. Miscellaneous loads, such as those due to temperature, rain, flood and surge etc. on buildings or structures, shall be determined in accordance with Sec
2.6. Structural members subject to miscellaneous loads, not specified in Sec 2.6 shall be designed using well established methods given in any reliable references, and complying with the other requirements of this Code.
### **1.6.2 Self-Straining Forces**
Self-straining forces such as those arising due to assumed differential settlements of foundations and from restrained dimensional changes due to temperature, moisture, shrinkage, creep, and similar effects, shall be taken into consideration in the design of structural members.
### **1.6.3 Stress Reversal and Fatigue**
Structural members and joints shall be investigated and designed against possible stress reversals caused due to various construction loads. Where required, allowance shall be made in the design to account for the effects of fatigue. The allowable stress may be appropriately reduced to account for such effects in the structural members.
### **1.6.4 Flood, Tidal/Storm Surge and Tsunami**
Buildings, structures and components thereof shall be designed, constructed and anchored to resist flotation, collapse or any permanent movement due to loads including flood, tidal/Storm surge and tsunami, when applicable. Structural members shall be designed to resist both hydrostatic and significant hydrodynamic loads and effects of buoyancy resulting from flood or surge. Flood and surge loads on buildings and structures shall be determined in accordance with Sec 2.6.3. Load combination including flood and surge loads shall conform to Sec 2.7. Design of foundations to sustain these load effects shall conform to the provisions of Sec 1.8.
Stability against overturning and sliding caused due to wind and flood or surge loads simultaneously shall be investigated, and such effects shall be resisted with a minimum factor of safety of 1.5, considering dead load only.
### **1.6.5 Rain Loads**
Roofs of the buildings and structures as well as their other components which may have the capability of retaining rainwater shall be designed for adequate gravity load induced by ponding. Roofs and such other components shall be analysed and designed for load due to ponding caused by accidental blockage of drainage system complying with Sec. 2.6.2.
### **1.6.6 Other Loads**
Buildings and structures and their components shall be analyzed and designed for stresses caused by the following effects:
* (a) Temperature Effects (Sec 2.6.4).
* (b) Soil and Hydrostatic Pressure (Sec 2.6.5).
* (c) Impacts and Collisions
* (d) Explosions (Sec 2.6.6).
* (e) Fire
* (f) Vertical Forces on Air Raid Shelters (Sec 2.6.7).
* (g) Loads on Helicopter Landing Areas (Sec 2.6.8).
* (h) Erection and Construction Loads (Sec 2.6.9).
* (i) Moving Loads for Crane Movements
* (j) Creep and Shrinkage
* (k) Dynamic Loads due to Vibrations
* (l) Construction Loads
Design of buildings and structures shall include loading and stresses caused by the above effects in accordance with the provisions set forth in Chapter 2.
## **1.7 Detailed Design Requirements**
### **1.7.1 General**
All structural framing systems shall comply with the requirements of this Section. Only the elements of the designated lateral force resisting systems can be used to resist design lateral forces specified in Chapter 2. The individual components shall be designed to resist the prescribed forces acting on them. Design of components shall also comply with the specific requirements for the materials contained in Chapters 4 to 13. In addition, such framing systems and components shall comply with the design requirements provided in this Section.
### **1.7.2 Structural Framing Systems**
The basic structural systems are defined in Sec 1.3.2 and shown in Table 6.1.3, and each type is subdivided by the types of framing elements used to resist the lateral forces. The structural system used shall satisfy requirements of seismic design category and height limitations indicated in Table 6.2.19. Special framing requirements are given in the following Sections in addition to those provided in Chapters 4 to 13.
### **1.7.3 Detailing Requirements for Combinations of Structural Systems**
For components common to different structural systems, a more restrictive detailing shall be provided.
#### 1.7.3.1 Connections to resist seismic forces
Connections which resist prescribed seismic forces shall be designed in accordance with the seismic design requirements provided in Chapters 4 to 13. Detailed sketches for these connections shall be given in the structural drawings.
#### 1.7.3.2 Deformation compatibility
All framing elements not required by design to be part of the lateral force resisting system, shall be investigated and shown to be adequate for vertical load carrying capacity when subjected to lateral displacements resulting from the seismic lateral forces. For designs using working stress methods, this capacity may be determined using an allowable stress increase of 30 percent. Geometric non-linear ($P$-$\Delta$) effects on such elements shall be accounted for.
* (a) Adjoining Rigid Elements : Moment resisting frames may be enclosed or adjoined by more rigid elements which would tend to prevent a space frame from resisting lateral forces where it can be shown that the action or failure of the more rigid elements will not impair the vertical and lateral load resisting ability of the space frame.
* (b) Exterior Elements : Exterior nonbearing, non-shear wall panels or elements which are attached to or enclose the exterior of a structure, shall be designed to resist the forces according to Sec. 2.5.15 of Chapter 2, if seismic forces are present, and shall accommodate movements of the structure resulting from lateral forces or temperature changes. Such elements shall be supported by structural members or by mechanical connections and fasteners joining them to structural members in accordance with the following provisions:
* (i) Connections and panel joints shall allow for a relative movement between storeys of not less than two times the storey drift caused by wind forces or design seismic forces, or 12 mm, whichever is greater.
* (ii) Connections to permit movement in the plane of the panel for storey drift shall be either sliding connections using slotted or oversized holes, connections which permit movement by bending of steel, or other connections providing equivalent sliding and ductility capacity.
* (iii) Bodies of connections shall have sufficient ductility and rotation capability to preclude any fracture of the anchoring elements or brittle failures at or near welding.
* (iv) Bodies of the connection shall be designed for 1.33 times the seismic force determined by Sec. 2.5.15 of Chapter 2, or equivalent.
* (v) All fasteners in the connection system, such as bolts, inserts, welds, dowels etc. shall be designed for 4 times the forces determined by Sec. 2.5.15 of Chapter 2 or equivalent.
* (vi) Fasteners embedded in concrete shall be attached to, or hooked around reinforcing steel, or otherwise terminated so as to transfer forces to the reinforcing steel effectively.
#### 1.7.3.3 Ties and continuity
All parts of a structure shall be interconnected. These connections shall be capable of transmitting the prescribed lateral force to the lateral force resisting system. Individual members, including those not part of the seismic force–resisting system, shall be provided with adequate strength to resist the shears, axial forces, and moments determined in accordance with this Code. Connections shall develop the strength of the connected members and shall be capable of transmitting the seismic force $(F_p)$ induced by the parts being connected.
#### 1.7.3.4 Collector elements
Collector elements shall be provided which are capable of transferring the lateral forces originating in other portions of the structure to the element providing the resistance to those forces.
#### 1.7.3.5 Concrete frames
When concrete frames are provided by design to be part of the lateral force resisting system, they shall conform to the provisions of Chapter 8 of this Part.
#### 1.7.3.6 Anchorage of concrete and masonry structural walls
The concrete and masonry structural walls shall be anchored to supporting construction. The anchorage shall provide a positive direct connection between the wall and floor or roof and shall be capable of resisting the horizontal forces specified in Sections 2.4.11 and 2.5.15, or a minimum force of 4.09 kN/m of wall. Walls shall be designed to resist bending between anchors where the anchor spacing exceeds 1.2 m. In masonry walls of hollow units or cavity walls, anchors shall be embedded in a reinforced grouted structural element of the wall. Deformations of the floor and roof diaphragms shall be considered in the design of the supported walls and the anchorage forces in the diaphragms shall be determined in accordance with Sec 1.7.3.9 below.
#### 1.7.3.7 Boundary members
Specially detailed boundary members shall be considered for shear walls and shear wall elements whenever their design is governed by flexure.
#### 1.7.3.8 Floor and roof diaphragms
Deflection in the plane of the diaphragm shall not exceed the permissible deflection of the attached elements. Permissible deflection shall be that deflection which will permit the attached element to maintain its structural integrity under the individual loading and continue to support the prescribed loads. Design of diaphragms shall also comply with the following requirements.
* (a) Diaphragm Forces: Diaphragms shall be designed to resist the seismic forces given in Sec 2.5 or for similar non-seismic lateral forces, whichever is greater.
* (b) Diaphragm Ties: Diaphragms supporting concrete or masonry walls shall have continuous ties, or struts between the diaphragm chords to distribute the anchorage forces specified in Sec 1.7.3.6 above. Added chords may be provided to form sub-diaphragms to transmit the anchorage forces to the main cross ties.
* (c) Wood Diaphragms: Where wood diaphragms are used to laterally support concrete or masonry walls, the anchorage shall conform to Sec 1.7.3.6 above. In seismic Zones 2, 3 and 4 the following requirements shall also apply:
* (i) Anchorage shall not be accomplished by use of toe nails or nails subject to withdrawal, nor shall wood ledgers or framing be used in cross-grain bending or cross-grain tension.
* (ii) The continuous ties required by paragraph (b) above, shall be in addition to the diaphragm sheathing.
* (d) Structures having irregularities
* (i) For structures assigned to Seismic Design Category D and having a plan irregularity of Type I, II, III, or IV in Table 6.1.5 or a vertical structural irregularity of Type IV in Table 6.1.4, the design forces determined from Sec 2.5.7 shall be increased 25 percent for connections of diaphragms to vertical elements and to collectors and for connections of collectors to the vertical elements. Collectors and their connections also shall be designed for these increased forces unless they are designed for the load combinations with over strength factor.
* (ii) For structures having a plan irregularity of Type II in Table 6.1.5, diaphragm chords and collectors shall be designed considering independent movement of any projecting wings of the structure. Each of these diaphragm elements shall be designed for the more severe of the following cases:
* Motion of the projecting wings in the same direction.
* Motion of the projecting wings in opposing directions.
**Exception:**
This requirement may be deemed to be satisfied if the procedures of Sec 2.5.8 when seismic forces are present, in conjunction with a three dimensional model, have been used to determine the lateral seismic forces for design.
#### 1.7.3.9 Framing below the base
When structural framings continue below the base, the following requirements shall be satisfied.
* (a) **Framing between the Base and the Foundation:** The strength and stiffness of the framing between the base and the foundation shall not be less than that of the superstructure. The special detailing requirements of Sec 8.3 or Sec 10.20, as appropriate for reinforced concrete or steel, shall apply to columns supporting discontinuous lateral force resisting elements and to SMF, IMF, and EBF system elements below the base that are required to transmit forces resulting from lateral loads to foundation.
* (b) **Foundations :** The foundation shall be capable of transmitting the design base shear and the overturning forces from the superstructure into the supporting soil, but the short term dynamic nature of the loads may be taken into account in establishing the soil properties. Sec 1.8 below prescribes the additional requirements for specific types of foundation construction.
## **1.8 Foundation Design Requirements**
### **1.8.1 General**
The design and construction of foundation, foundation components and connection between the foundation and superstructure shall conform to the requirements of this Section and applicable provisions of Chapter 3 and other portions of this Code.
### **1.8.2 Soil Capacities**
The bearing capacity of the soil, or the capacity of the soil-foundation system including footing, pile, pier or caisson and the soil, shall be sufficient to support the structure with all prescribed loads, considering the settlement of the structure. For piles, this refers to pile capacity as determined by pile-soil friction and bearing which may be determined in accordance with the provisions of Chapter 3. For the load combination including earthquake, the soil capacity shall be sufficient to resist loads at acceptable strains considering both the short time loading and the dynamic properties of the soil. The stress and settlement of soil under applied loads shall be determined based on established methods of Soil Mechanics.
### **1.8.3 Superstructure-to-Foundation Connection**
The connection of superstructure elements to the foundation shall be adequate to transmit to the foundation the forces for which the elements are required to be designed.
### **1.8.4 Foundation-Soil Interface**
For regular buildings the base overturning moments for the entire structure or for any one of its lateral force-resisting elements, shall not exceed two-thirds of the dead load resisting moment. The weight of the earth superimposed over footings may be used to calculate the dead load resisting moment.
### **1.8.5 Special Requirements for Footings, Piles and Caissons in Seismic Zones 2, 3 and 4**
#### 1.8.5.1 Piles and caissons
Piles and caissons shall be designed for flexure whenever the top of such members is anticipated to be laterally displaced by earthquake motions. The criteria and detailing requirements of Sec 8.3 for concrete and Sec 10.20 for steel shall apply for a length of such members equal to 120 percent of the flexural length.
#### 1.8.5.2 Footing interconnection
* (a) Footings and pile caps shall be completely interconnected by strut ties or other equivalent means to restrain their lateral movements in any orthogonal direction.
* (b) The strut ties or other equivalent means as specified in (a) above, shall be capable of resisting in tension or compression a force not less than 10% of the larger footing or column load unless it can be demonstrated that equivalent restraint can be provided by frictional and passive soil resistance or by other established means.
### **1.8.6 Retaining wall design**
Retaining walls shall be designed to resist the lateral pressure of the retained material, under drained or undrained conditions and including surcharge, in accordance with established engineering practice. For such walls, the minimum factor of safety against base overturning and sliding due to applied earth pressure shall be 1.5.
## **1.9 Design and Construction Review**
Every building or structure designed shall have its design documents prepared in accordance with the provisions of Sec 1.9.1. The minimum requirements for design review and construction observation shall be those set forth under Sections 1.9.2 and 1.9.3 respectively.
### **1.9.1 Design Document**
The design documents shall be prepared and signed by the Engineer responsible for the structural design of any building or structure intended for construction. The design documents shall include a design report, material specifications and a set of structural drawings, which shall be prepared in compliance with Sections 1.9.2 and 1.9.3 below for submittal to the concerned authority. For the purpose of this provision, the concerned authority shall be either persons from the government approval agency for the construction, or the owner of the building or the structure, or one of his representatives.
### **1.9.2 Design Report**
The design report shall contain the description of the structural design with basic design information as provided below, so that any other structural design engineer will be able to independently verify the design parameters and the member sizes using these basic information. The design report shall include, but not be limited to, the following:
* (a) Mention of this Code including relevant Part, Chapter and Section.
* (b) Name of other referenced standards, and the specific portions, stating chapter, section etc. of these Code and standards including any specialist report used for the structural design.
* (c) Methods used for the calculation of all applied loads along with basic load coefficients and other basic information including any assumption or judgment made under special circumstances.
* (d) A drawing of the complete mathematical model prepared in accordance with Sec 1.2.7.1 to represent the structure and showing on it the values, locations and directions of all applied loads, and location of the lateral load resisting systems such as shear walls, braced frames etc.
* (e) Methods of structural analysis, and results of the analysis such as shear, moment, axial force etc., used for proportioning various structural members and joints including foundation members.
* (f) Methods of structural design including types and strength of the materials of construction used for proportioning the structural members.
* (g) Reference of the soil report or any other documents used in the design of the structure, foundation or components thereof.
* (h) Statement supporting the validity of the above design documents with date and signature of the engineer responsible for the structural design.
* (i) When computer programs are used, to any extent, to aid in the analysis or design of the structure, the following items, in addition to items (a) to (g) above, shall be required to be included in the design report:
* (i) A sketch of the mathematical model used to represent the structure in the computer generated analysis.
* (ii) The computer output containing the date of processing, program identification, identification of structures being analysed, all input data, units and final results. The computer input data shall be clearly distinguished from those computed in the program.
* (iii) A program description containing the information necessary to verify the input data and interpret the results to determine the nature and extent of the analysis and to check whether the computations comply with the provisions of this Code.
* (iv) The first sheet of each computer run shall be signed by the engineer responsible for the structural design.
### **1.9.3 Structural Drawings and Material Specifications**
The structural drawings shall include, but not be limited to, the following:
* (a) The first sheet shall contain :
* (i) Identification of the project to which the building or the structure, or portion thereof belongs,
* (ii) Reference to the design report specified in Sec 1.9.2 above,
* (iii) Date of completion of design, and
* (iv) Identification and signature with date of the engineer responsible for the structural design.
* (b) The second sheet shall contain detail material specifications showing:
* (i) Specified compressive strength of concrete at stated ages or stages of construction for which each part of structure is designed.
* (ii) Specified strength or grade of reinforcement
* (iii) Specified strength of prestressing tendons or wires
* (iv) Specified strength or grade of steel
* (v) Specified strengths for bolts, welds etc.
* (vi) Specified strength of masonry, timber, bamboo, ferrocement
* (vii) Minimum concrete compressive strength at time of post-tensioning
* (viii) Stressing sequence for post-tensioning tendons
* (ix) General notes indicating clear cover, development lengths of reinforcements, or any other design parameter relevant to the member or connection details provided in drawings to be followed, as applicable, and
* (x) Identification and signature with date of the Engineer responsible for the structural design.
* (c) Drawing sheets, other than the first two, shall include structural details of the elements of the structure clearly showing all sizes, cross-sections and relative locations, connections, reinforcements, laps, stiffeners, welding types, lengths and locations etc. whichever is applicable for a particular construction. Floor levels, column centres and offset etc., shall be dimensioned. Camber of trusses and beams, if required, shall be shown on drawings. For bolt connected members, connection types such as slip, critical, tension or bearing type, shall be indicated on the drawing.
* (d) Drawings shall be prepared to a scale large enough to show the information clearly and the scales shall be marked on the drawing sheets. If any variation from the design specifications provided in sheet two occurs, the drawing sheet shall be provided additionally with the design specifications including material types and strength, clear cover and development lengths of reinforcements, or any other design parameter relevant to the member or connection details provided in that drawing sheet. Each drawing sheet shall also contain the signature with date of the engineer responsible for the structural design.
### **1.9.4 Design Review**
The design documents specified in Sec 1.9.1 shall be available for review when required by the concerned authority. Review shall be accomplished by an independent structural engineer qualified for this task and appointed by the concerned authority. Design review shall be performed through independent calculations, based on the information provided in the design documents prepared and signed by the original structural design engineer, to verify the design parameters including applied loads, methods of analysis and design, and final design dimensions and other details of the structural elements. The reviewing engineer shall also check the sufficiency and appropriateness of the supplied structural drawings for construction.
### **1.9.5 Construction Observation**
Construction observation shall be performed by a responsible person who will be a competent professional appointed by the owner of the building or the structure. Construction observation shall include, but not be limited to, the following:
* (a) Specification of an appropriate testing and inspection schedule prepared and signed with date by the responsible person;
* (b) Review of testing and inspection reports; and
* (c) Regular site visit to verify the general compliance of the construction work with the structural drawings and specifications provided in Sec 1.9.3 above.
# Chapter 10: Steel Structures
Source: https://docs.sayed.app/bnbc/part-6-structural-design/chapter-10-steel-structures
## **10.1 General Provisions for Structural Steel Buildings and Structures**
This Section states the scope of the Specification, summarizes referenced Specification, code, and standard documents, and provide requirements for materials and contract documents.
### **10.1.1 Scope**
The specification contained in Chapter 10 Part 6 of this Code sets forth criteria for the design, fabrication, and erection of structural steel buildings and other structures, where other steel-structures are defined as those structures designed, fabricated, and erected in a manner similar to steel-buildings, with building-like vertical and lateral load resisting elements. Where conditions are not covered by this specification, designs are permitted to be based on tests or analysis, subject to the approval of the authority having jurisdiction. Alternate methods of analysis and design shall be permitted, provided such alternate methods or criteria are acceptable to the authority having jurisdiction.
#### 10.1.1.1 Low-seismic applications
When the seismic response modification coefficient, *R* (as specified in Chapter 2 Part 6) is taken equal to or less than 3, the design, fabrication, and erection of structural-steel-framed buildings and other steel-structures shall comply with this specification except that such structures need not to comply with the specifications set forth in Sec 10.20 Seismic Provisions.
#### 10.1.1.2 High-seismic applications
When the seismic response modification coefficient, *R* (as specified in Chapter 2 Part 6) is taken greater than 3, the design, fabrication and erection of structural-steel-framed buildings and other structures shall comply with the requirements in the Sec 10.20 Seismic Provisions, in addition to the provisions of other sections (whichever applicable) this specification.
### **10.1.2 Symbols, Glossary and Referenced Specifications, Codes and Standards**
#### 10.1.2.1 Symbols
The Section or Table number in the right-hand column refers to where the symbol is first used.
| **Symbol** | **Meaning** | **Section** |
| ------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------- |
| *A* | Column cross-sectional area, mm2 | 10.10.10.6 |
| *A* | Total cross-sectional area of member, mm2 | 10.5.7.2 |
| *ABM* | Cross-sectional area of the base metal, mm2 | 10.10.2.4 |
| $A_b$ | Nominal unthreaded body area of bolt or threaded part, mm2 | 10.10.3.6 |
| $A_b$ | Cross-sectional area of a horizontal boundary element (HBE),
mm2 | 10.20.17.2.1 |
| $A_{bi}$ | Cross-sectional area of the overlapping branch, mm2 | 10.11.2.3 |
| $A_{bj}$ | Cross-sectional area of the overlapped branch, mm2 | 10.11.2.3 |
| $A_c$ | Cross-sectional area of a vertical boundary element
(VBE),mm2 | 10.20.17.2.1 |
| $A_D$ | Area of an upset rod based on the major thread diameter, mm2 | Table 6.10.10 |
| $A_e$ | Effective net area, mm2 | 10.4.2 |
| $A_{eff}$ | Summation of the effective areas of the cross section based on
the reduced effective width, $b_e$, mm2 | 10.5.7.2 |
| $A_f$ | Flange area, mm2 | 10.20.8 |
| $A_{fc}$ | Area of compression flange | 10.7.3.1 |
| $A_{fg}$ | Gross tension flange area, mm2 | 10.6.13.1 |
| $A_{fn}$ | Net tension flange area, mm2 | 10.6.13.1 |
| $A_{ft}$ | Area of tension flange, mm2 | 10.7.3.1 |
| $A_g$ | Gross area of member, mm2 | 10.2.3.13 |
| $A_g$ | Gross area of section based on design wall thickness, mm2 | 10.7.6 |
| $A_g$ | Chord gross area, mm2 | 10.11.2.2 |
| $A_g$ | Gross area, mm2 | 10.20.9 |
| $A_{gv}$ | Gross area subject to shear, mm2 | 10.10.4.3 |
| $A_n$ | Net area of member, mm2 | 10.2.3.13 |
| $A_{nt}$ | Net area subject to tension, mm2 | 10.10.4.3 |
| $A_{nv}$ | Net area subject to shear, mm2 | 10.10.4.2 |
| $A_{pb}$ | Projected bearing area, mm2 | 10.10.7 |
| $A_{sc}$ | Area of the yielding segment of steel core, mm2 | 10.20.16 |
| $A_{sf}$ | Shear area on the failure path, mm2 | 10.4.5.1 |
| $A_{st}$ | Stiffener area, mm2 | 10.7.3.3 |
| $A_{st}$ | Area of link stiffener, mm2 | 10.20.15 |
| $A_t$ | Net tensile area, mm2 | 10.17.4 |
| $A_w$ | Web area, the overall depth times the web thickness,,
mm2 | 10.7.2.1 |
| $A_w$ | Effective area of the weld, mm2 | 10.10.2.4 |
| $A_w$ | Link web area, mm2 | 10.20.15 |
| $A_{wi}$ | Effective area of weld throat of anythweld element, mm2 | 10.10.2.4 |
| $A_1$ | Area of steel concentrically bearing on a concrete support, mm2 | 10.10.8 |
| $A_2$ | Maximum area of the portion of the supporting surface that is
geometrically similar to and concentric with the loaded area,
mm2. | 10.10.8 |
| $B$ | Factor for lateral-torsional buckling in tees and double angles | 10.6.9.2 |
| $B$ | Overall width of rectangular HSS member, measured 90oto the
plane of connection, mm. | 10.11.1.1,
Table 6.10.2 |
| $B$ | Overall width of rectangular HSS main member, measured 90o
to the plane of the connection,mm. | 10.11.2.1,
10.11.3.1 |
| $B_b$ | Overall width of rectangular HSS branch member, measured
90oto the plane of the connection, mm. | 10.11.2.1,
10.11.3.1 |
| $B_{bi}$ | Overall branch width of the overlapping branch | 10.11.2.3 |
| $B_{bj}$ | Overall branch width of the overlapped branch | 10.11.2.3 |
| $B_p$ | Width of plate, measure 90oto the plane of the connection, mm. | 10.11.1.1 |
| $B_p$ | Width of plate, transverse to the axis of the main member,mm. | 10.11.2.3 |
| , | Factors used in determiningfor combined bending and
axial forces when first-order analysis is employed | 10.3.2.1 |
| $C$ | HSS torsional constant | 10.8.3.1 |
| $C_a$ | Ratio of required strength to available strength | Table 6.10.8 |
| $C_b$ | Lateral-torsional buckling modification factor for nonuniform
moment diagrams when both ends of the unsupported segment
are braced | 10.6.1 |
| $C_d$ | Coefficient relating relative brace stiffness and curvature | 10.19.3.1,
10.20.9 |
| $C_d$ | Deflection amplification factor | P.2 |
| $C_f$ | Constant based on stress category, given in Table 6.10.14 | 10.17.3 |
| $C_m$ | Coefficient assuming no lateral translation of the frame | 10.3.2.1 |
| $C_p$ | Ponding flexibility coefficient for primary member in a flat roof | 10.16.1 |
| $C_r$ | Coefficient for web sidesway buckling | 10.10.10.4 |
| $C_r$ | Parameter used for determining the approximate fundamental
period | P.2 |
| $C_s$ | Ponding flexibility coefficient for secondary member in a flat
roof | 10.16.1 |
| $C_v$ | Web shear coefficient | 10.7.2.1 |
| $C_w$ | Warping constant, mm6 | 10.5.4 |
| $D$ | Nominal dead load | 10.16.2 |
| $D$ | Dead load due to the weight of the structural elements and
permanent features on the building, N. | 10.20.9 |
| $D$ | Outside diameter of round HSS, mm. | Table 6.10.8 |
| $D$ | Outside diameter of round HSS member, mm. | Table 6.10.1 |
| $D$ | Outside diameter of round HSS member, mm. | 10.11.1.1 |
| $D$ | Outside diameter of round HSS main member, mm. | 10.11.2.1 |
| $D$ | Outside diameter of round HSS main member, mm. | 10.11.3.1 |
| $D$ | Outside diameter, mm. | 10.5.7.2 |
| $D$ | Chord diameter, mm. | 10.11.2.2 |
| $D_b$ | Outside diameter of round HSS branch member,mm. | 10.11.2.1 |
| $D_b$ | Outside diameter of round HSS branch member,mm. | 10.11.3.1 |
| $D_s$ | Factor used in Eq. 6.10.144, dependent on the type of
transverse stiffeners used in a plate girder | 10.7.3.3 |
| $D_u$ | In slip-critical connections, a multiplier that reflects the ratio of the mean installed bolt pretension to the specified minimum bolt pretension | 10.10.3.8 |
| *E* | Earthquake load | 10.20.4 |
| *E* | Effect of horizontal and vertical earthquake-induced loads | 10.20.9 |
| *E* | Modulus of elasticity of steel, $E$ = 200,000 MPa | 10.20.8 |
| $E$ | Eccentricity in a truss connection, positive being away from
the branches, mm. | 10.11.2.1 |
| $E$ | Modulus of elasticity of steel = 200000 MPa | Table 6.10.1 |
| $E_c$ | Modulus of elasticity of concrete, MPa. | 10.18.2.3 |
| $E_{cm}$ | Modulus of elasticity of concrete at elevated temperature, MPa | |
| *EI* | Flexural elastic stiffness of the chord members of special
segment, (N-mm2) | 10.20.12 |
| $E_m$ | Modulus of elasticity of steel at elevated temperature, MPa. | 10.18.2.3 |
| $F_a$ | Available axial stress at the point of consideration, MPa. | 10.8.2 |
| $F_{BM}$ | Nominal strength of the base metal per unit area, MPa. | 10.10.2.4 |
| $F_{BW}$ | Available flexural stress at the point of consideration about the
major axis, MPa. | 10.8.2 |
| $F_{bz}$ | Available flexural stress at the point of consideration about the
minor axis, MPa. | 10.8.2 |
| $F_c$ | Available stress, MPa. | 10.11.2.2 |
| $F_{cr}$ | Critical stress, MPa. | 10.5.3 |
| $F_{cr}$ | Buckling stress for the section as determined by analysis, MPa. | 10.6.12.2 |
| $F_{cry}$ | Critical stress about the minor axis, MPa. | 10.5.4 |
| $F_{crz}$ | Critical torsional buckling stress, MPa. | 10.5.4 |
| $F_e$ | Elastic critical buckling stress, MPa. | 10.3.1.3 |
| $F_{ex}$ | Elastic flexural buckling stress about the major axis, MPa. | 10.5.4 |
| $F_{EXX}$ | Electrode classification number, MPa. | 10.10.2.4 |
| $F_{ey}$ | Elastic flexural buckling stress about the minor axis, MPa. | 10.5.4 |
| $F_{ez}$ | Elastic torsional buckling stress, MPa. | 10.5.4 |
| $F_L$ | A calculated stress used in the calculation of nominal flexural
strength, MPa. | Table 6.10.1 |
| $F_n$ | Nominal torsional strength | 10.8.3.3 |
| $F_n$ | Nominal tensile stress $F_{nt}$, or shear stress, $F_{nv}$, from Table
6.10.10, MPa. | 10.10.3.6 |
| $F_{nt}$ | Nominal tensile stress from Table 6.10.10, MPa. | 10.10.3.7 |
| $F_{nt}'$ | Nominal tensile stress modified to include the effects of
shearing stress, MPa. | 10.10.3.7 |
| $F_{nv}$ | Nominal shear stress from Table 6.10.10, MPa. | 10.10.3.7 |
| $F_{SR}$ | Design stress range, MPa. | 10.17.3 |
| $F_{TH}$ | Threshold fatigue stress range, maximum stress range for
indefinite design life from Table 6.10.14, MPa. | 10.17.1 |
| $F_u$ | Specified minimum tensile strength of the type of steel being
used, MPa. | 10.4.2 |
| $F_u$ | Specified minimum tensile strength of the connected material,
MPa. | 10.10.3.10 |
| $F_u$ | Specified minimum tensile strength of HSS material, MPa. | 10.11.1.1 |
| $F_u$ | Specified minimum tensile strength of HSS material, MPa. | 10.11.2.1 |
| $F_u$ | Ultimate strength of HSS member, MPa. | 10.11.3.1 |
| $F_u$ | Specified minimum tensile strength, MPa. | 10.20.6 |
| $F_{um}$ | Specified minimum tensile strength of the type of steel being
used at elevated temperature, MPa. | 10.18.2 |
| $F_w$ | Nominal strength of the weld metal per unit area, MPa. | 10.10.2.4 |
| $F_{wi}$ | Nominal stress in any $i^{th}$ weld element, MPa. | 10.10.2.4 |
| $F_{wix}$ | x component of stress $F_{wi}$, MPa. | 10.10.2.4 |
| $F_{wiy}$ | y component of stress $F_{wi}$, MPa. | 10.10.2.4 |
| $F_y$ | Specified minimum yield stress of the type of steel being
used, MPa. As used in this Specification, “yield stress” | 10.20.6,
Table 6.10.1 |
| $F_y$ | denotes either the specified minimum yield point (for those
steels that have a yield point) or specified yield strength (for
those steels that do not have a yield point | |
| $F_y$ | Specified minimum yield stress of the compression flange, MPa. | 10.15.3 |
| $F_y$ | Specified minimum yield stress of the column web, MPa. | 10.10.10.6 |
| $F_y$ | Specified minimum yield stress of HSS member material, MPa. | 10.11.1.1 |
| $F_y$ | Specified minimum yield stress of HSS main member material,
MPa. | 10.11.2.1 |
| $F_y$ | Specified minimum yield stress of HSS main member, MPa. | 10.11.3.1 |
| $F_{yb}$ | Specified minimum yield stress of HSS branch member
material, MPa. | 10.11.2.1 |
| $F_{yb}$ | Specified minimum yield stress of HSS branch member, MPa. | 10.11.3.1 |
| $F_{yb}$ | $F_y$ of a beam, MPa. | 10.20.9 |
| $F_{yc}$ | $F_y$ of a column, MPa. | 10.20.9 |
| $F_{ybi}$ | Specified minimum yield stress of the overlapping branch
material, MPa. | 10.11.2.3 |
| $F_{yf}$ | Specified minimum yield stress of the flange, MPa. | 10.10.10.1 |
| $F_{ym}$ | Specified minimum yield stress of the type of steel used at
elevated temperature, MPa. | 10.18.2 |
| $F_{yp}$ | Specified minimum yield stress of plate, MPa. | 10.11.1.1 |
| $F_{ysc}$ | Specified minimum yield stress of the steel core, or actual yield
stress of the steel core as determined from a coupon test, MPa. | 10.20.16 |
| $F_{yst}$ | Specified minimum yield stress of the stiffener material, MPa. | 10.7.3.3 |
| $F_{yw}$ | Specified minimum yield stress of the web, MPa. | 10.10.10.2 |
| $G$ | Shear modulus of elasticity of steel = 77 200 MPa. | 10.5.4 |
| $G$ | Gap between toes of branch members in a gapped K-
connection, neglecting welds, mm. | 10.11.2.1 |
| $H$ | Flexural constant | 10.5.4 |
| $H$ | Overall height of rectangular HSS member, measured in the
plane of connection, mm. | 10.11.1.1 |
| $H$ | Overall height of rectangular HSS main member, measured in
plane of connection, mm. | 10.11.2.1 |
| $H$ | Overall height of rectangular HSS main member, measured in
plane of connection, mm. | 10.11.3.1 |
| $H$ | Overall height of rectangular HSS member, measured in the
plane of connection, mm. | Table 6.10.2 |
| $H$ | The load length parameter, applicable only to rectangular | 10.11.2.1 |
| $H$ | HSS; the ratio of the length of contact of the branch with the
chord in the plane of the connection to the chord width = $N/B$, where, $N = H_b/\sin\theta$ | |
| $H$ | Height of story, which may be taken as the distance between | 10.20.8 |
| $H$ | the centerline of floor framing at each of the levels above and
below, or the distance between the top of floor slabs at each of
the levels above and below, mm | |
| $H_b$ | Overall height of rectangular HSS branch member, measured
in the plane of the connection, mm. | 10.11.3.1 |
| $H_b$ | Overall height of rectangular HSS branch member, measured
in the plane of the connection, mm. | 10.11.2.1 |
| $H_{bi}$ | Overall depth of the overlapping branch | 10.11.2.3 |
| $\Sigma H$ | Story shear produced by the lateral forces used to compute $\Delta_H$,
N. | 10.3.2.1 |
| $I$ | Moment of inertia in the place of bending, mm4. | 10.3.2.1 |
| $I$ | Moment of inertia about the axis of bending, mm4. | 10.14.3 |
| $I$ | Moment of inertia, mm4 | 10.20.12 |
| $I_c$ | Moment of inertia of a vertical boundary element (VBE) taken
perpendicular to the direction of the web plate line, mm4 | 10.20.17 |
| $I_d$ | Moment of inertia of the steel deck supported on secondary
members, mm4 | 10.16.1 |
| $I_p$ | Moment of inertia of primary members, mm4 | 10.16.1 |
| $I_s$ | Moment of inertia of secondary members, mm4 | 10.16.1 |
| $I_x, I_y$ | Moment of inertia about the principal axes, mm4 | 10.5.4 |
| $I_y$ | Out-of-plane moment of inertia, mm4 | 10.19.2 |
| $I_z$ | Minor principal axis moment of inertia, mm4 | 10.6.10.2 |
| $I_{yc}$ | Moment of inertia about y-axis referred to the compression | 10.6.1 |
| $I_{yc}$ | flange, or if reverse curvature bending referred to smaller
flange, mm4 | |
| $J$ | Torsional constant, mm4 | 10.5.4 |
| $K$ | Effective length factor determined in accordance with Sec 10.3 | 10.3.1.2 |
| $K$ | Effective length factor for prismatic member | 10.20.13 |
| $K_z$ | Effective length factor for torsional buckling | 10.5.4 |
| $K_1$ | Effective length factor in plane of bending, calculated based on
the assumption of no lateral translation set equal to 1.0 unless
analysis indicates a smaller value to be used. | 10.3.2.1 |
| $K_2$ | Effective length factor in the plane of bending, calculated based
on a sidesway buckling analysis | 10.3.2.1 |
| $L$ | Story height, mm. | 10.3.2.1 |
| $L$ | Laterally unbraced length of a member, mm. | 10.5.2 |
| $L$ | Length of member between work points at truss chord
centerlines,mm. | 10.5.5 |
| $L$ | Length of the member, mm. | 10.8.3 |
| $L$ | Actual length of end-loaded weld, mm. | 10.10.2.2 |
| $L$ | Nominal occupancy live load | 10.18.1.4 |
| $L$ | Span length, mm. | 10.19.2 |
| $L$ | Span length of the truss, mm. | 10.20.12 |
| $L$ | Distance between VBE centerlines, mm | 10.20.17 |
| $L_b$ | Distance between braces, mm. | 10.19.2 |
| $L_b$ | Length between points that are either braced against lateral | 10.6.2, |
| $L_b$ | displacement of compression flange or braced against twist of
the cross section, mm. | 10.20.13 |
| $L_c$ | Distance between plastic hinge locations, mm | 10.20.9 |
| $L_c$ | Clear distance, in the direction of the force, between the edge | 10.10.3.10 |
| $L_c$ | of the hole and the edge of the adjacent hole or edge of the
material,mm. | |
| $L_c$ | Link length, mm | 10.20.15 |
| $L_{cf}$ | Clear distance between VBE flanges, mm | 10.20.17 |
| $L_e$ | Total effective weld length of groove and fillet welds to
rectangular HSS,mm. | 10.11.2.3 |
| $L_p$ | Limiting laterally unbraced length for the limit state of
yielding, mm. | 10.6.2.2 |
| $L_p$ | Column spacing in direction of girder, m | 10.16 |
| $L_p$ | Limiting laterally unbraced length for full plastic flexural
strength, uniform moment case,mm. | 10.20.12 |
| $L_{pd}$ | Limiting laterally unbraced length for plastic analysis, mm. | 10.15.7 |
| $L_{pd}$ | Limiting laterally unbraced length for plastic analysis, mm | 10.20.13 |
| $L_q$ | Maximum unbraced length for $M_r$ (the required flexural
strength),mm. | 10.19.2 |
| $L_r$ | Limiting laterally unbraced length for limit state of inelastic
lateral-torsional buckling, mm. | 10.6.2.2 |
| $L_s$ | Column spacing perpendicular to direction of girder, m | 10.16.1 |
| $L_s$ | Length of the special segment, mm | 10.20.12 |
| $L_v$ | Distance from maximum to zero shear force,mm. | 10.7.6 |
| $M_A$ | Absolute value of moment at quarter point of the unbraced
segment, N-mm. | 10.6.1 |
| $M_a$ | Required flexural strength in chord, using ASD load
combinations, N-mm. | 10.11.2.2 |
| $M_a$ | Required flexural strength, using ASD load combinations,
N-mm. | 10.20.9 |
| $M_{av}$ | Additional moment due to shear amplification from the
location of plastic hinge to the column centerline based on ASD
load combinations, N-mm. | 10.20.9 |
| $M_B$ | Absolute value of moment at centerline of the unbraced
segment, N-mm. | 10.6.1 |
| $M_{br}$ | Required bracing moment,N-mm. | 10.19.2 |
| $M_C$ | Absolute value of moment at three-quarter point of unbraced
segment, N-mm. | 10.6.1 |
| $M_{C(x,y)}$ | Available flexural strength determined in accordance with Sec
10.6,N-mm. | 10.8.1.1 |
| $M_{Cx}$ | Available flexural-torsional strength for strong axis flexure
determined in accordance with Sec 10.6,N-mm. | 10.8.1.3 |
| $M_e$ | Elastic lateral-torsional buckling moment, N-mm. | 10.6.10.2 |
| $M_{lt}$ | First-order moment under LRFD or ASD load combinations
caused by lateral translation of the frame only, N-mm. | 10.3.2.1 |
| $M_{max}$ | Absolute value of maximum moment in the unbraced
segment,N-mm. | 10.6.1 |
| $M_n$ | Nominal flexural strength, N-mm. | 10.6.1 |
| $M_n$ | Nominal flexural strength, N-mm. | 10.20.11 |
| $M_{nc}$ | Nominal flexural strength of the chord member of special
segment, N-mm. | 10.20.12 |
| $M_{nt}$ | First-order moment using LRFD or ASD load combinations
assuming there is no lateral translation of the frame, N-mm. | 10.3.2.1 |
| $M_p$ | Plastic bending moment,N-mm. | Table 6.10.1 |
| $M_p$ | Nominal plastic flexural strength, N-mm. | Table 6.10.8 |
| $M_{pa}$ | Nominal plastic flexural strength modified by axial load, N-
mm. | 10.20.15 |
| $M_{pb}$ | Nominal plastic flexural strength of the beam, N-mm. | 10.20.9 |
| $M_{pc}$ | Nominal plastic flexural strength of the column, N-mm. | 10.20.8 |
| $M_{p,exp}$ | Expected plastic moment, N-mm. | 10.20.9 |
| $M_r$ | Required second-order flexural strength under LRFD or ASD
load combinations, N-mm. | 10.3.2.1 |
| $M_r$ | Required flexural strength using LRFD or ASD load
combinations,N-mm. | 10.8.1 |
| $M_r$ | Required flexural strength in chord, N-mm. | 10.11.2.2 |
| $M_r$ | Expected flexural strength, N-mm. | 10.20.9 |
| $M_{r-ip}$ | Required in-plane flexural strength in branch,N-mm. | 10.11.3.2 |
| $M_{r-op}$ | Required out-of-plane flexural strength in branch,N-mm. | 10.11.3.2 |
| $M_u$ | Required flexural strength, using LRFD load combinations, N-
mm. | 10.20.9 |
| $M_u$ | Required flexural strength in chord, using LRFD load
combinations,N-mm. | 10.11.2.2 |
| $M_{uv}$ | Additional moment due to shear amplification from the location of plastic hinge to the column centerline based on LRFD load combinations, N-mm. | 10.20.9 |
| $M_{u,exp}$ | Expected required flexural strength, N-mm. | 10.20.15 |
| $M_y$ | Yield moment about the axis of bending, N-mm. | Table 6.10.1 |
| $M_1$ | Smaller moment, calculated from a first-order analysis, at the
ends of that portion of the member unbraced in the plane of
bending under consideration, N-mm. | 10.3.2.1 |
| $M_2$ | Larger moment, calculated from a first-order analysis, at the ends of that portion of the member unbraced in the plane of bending under consideration, N-mm. | 10.3.2.1 |
| $N$ | Length of bearing (not less than\_k\_for end beam reactions),mm. | 10.10.10.2 |
| $N$ | Bearing length of the load, measured parallel to the axis of the | 10.11.1.1 |
| $N$ | HSS member, (or measured across the width of the HSS in the
case of the loaded cap plates), mm. | |
| $N$ | Number of stress range fluctuations in design life | 10.17.3 |
| $N_b$ | Number of bolts carrying the Applied tension | 10.10.3.9 |
| $N_i$ | Additional lateral load | 10.3.2.2 |
| $N_i$ | Notional lateral load Applied at level $i$, N. | 10.14.3 |
| $N_s$ | Number of slip planes | 10.10.3.8 |
| $O_v$ | Overlap connection coefficient | 10.11.2.2 |
| $P$ | Pitch, mm per thread | 10.17.4 |
| $P_a$ | Required axial strength of a column using ASD load
combinations, N. | 10.20.8 |
| $P_{ac}$ | Required compressive strength using ASD load combinations,
N. | 10.20.9 |
| $P_b$ | Required strength of lateral brace at ends of the link, N. | 10.20.15 |
| $P_{br}$ | Required brace strength, N. | 10.19.2 |
| $P_c$ | Available axial compressive strength, N. | 10.8.1.1 |
| $P_c$ | Available tensile strength, N. | 10.8.1.2 |
| $P_c$ | Available axial strength of a column, N. | 10.20.9 |
| $P_{co}$ | Available compressive strength out of the plane of bending, N. | 10.8.1.3 |
| $P_{e1},P_{e2}$ | Elastic critical buckling load for braced and unbraced frame,
respectively, N. | 10.3.2.1 |
| $P_{eL}$ | Euler buckling load, evaluated in the plane of bending, N. | 10.14.3 |
| $P_{l(t,c)}$ | First-order axial force using LRFD or ASD load combinations
as a result of lateral translation of the frame only (tension or
compression, N. | 10.3.2.1 |
| $P_{n(t,c)}$ | First-order axial force using LRFD or ASD load combinations, | 10.3.2.1 |
| $P_{n(t,c)}$ | assuming there is no lateral translation of the frame (tension or
compression, N. | |
| $P_n$ | Nominal axial strength, N. | 10.4.2 |
| $P_n$ | Nominal axial strength of a column, N. | 10.20.8 |
| $P_{nc}$ | Nominal axial compressive strength of diagonal members of
the special segment, N. | 10.20.12 |
| $P_{nt}$ | Nominal axial tensile strength of diagonal members of special
segment, N. | 10.20.12 |
| $P_{rc}$ | Required compressive strength using ASD or LRFD load
combinations, N. | 10.20.9 |
| $P_r$ | Required second-order axial strength using LRFD or ASD load
combinations, N. | 10.3.2.1 |
| $P_r$ | Required axial compressive strength using LRFD or ASD load
combinations, N. | 10.3.2.2 |
| $P_r$ | Required tensile strength using LRFD or ASD load
combinations, N. | 10.8.1.2 |
| $P_r$ | Required strength, N. | 10.10.10.6 |
| $P_r$ | Required axial strength in chord, N. | 10.11.2.2 |
| $P_r$ | Required axial strength in branch, N. | 10.11.3.2 |
| $P_r$ | Required compressive strength, N. | 10.20.15 |
| $P_u$ | Required axial strength in compression, N. | 10.15.4 |
| $P_u$ | Required axial strength of a column or a link in LRFD load
combinations, N. | 10.20.8 |
| $P_{uc}$ | Required
compressive
strength
using
LRFD
load
combinations, N. | 10.20.9 |
| $P_y$ | Member yield strength, N. | 10.3.2.2 |
| $P_y$ | Nominal axial yield strength of a member, equal to $F_yA_g$, N. | Table 6.10.8 |
| $P_{ysc}$ | Axial yield strength of steel core, N. | 10.20.16 |
| $Q$ | Full reduction factor for slender compression elements | 10.5.7 |
| $Q_a$ | Reduction factor for slender stiffened compression elements | 10.5.7.2 |
| $Q_b$ | Maximum unbalanced vertical load effect applied to a beam by
the braces, N. | 10.20.13 |
| $Q_1$ | Axial forces and moments generated by at least 1.25 times the
expected nominal shear strength of the link | 10.20.15 |
| $Q_f$ | Chord-stress interaction parameter | 10.11.2.2 |
| $Q_s$ | Reduction factor for slender unstiffened compression elements | 10.5.7.1 |
| *R* | Seismic response modification coefficient | 10.20.1 |
| $R$ | Seismic response modification coefficient | 10.1.1.1 |
| $R$ | Nominal load due to rainwater or snow, exclusive of the
ponding contribution, MPa. | 10.16.2 |
| $R_a$ | Required strength (ASD) | 10.2.3.4 |
| $R_{FIL}$ | Reduction factor for joints using a pair of transverse fillet welds
only | 10.17.3 |
| $R_m$ | Factor in Eq. 6.10.8 dependent on type of system | 10.3.2.1 |
| $R_m$ | Cross-section monosymmetry parameter | 10.6.1 |
| $R_n$ | Nominal strength, N. | 10.2.3.3 |
| $R_n$ | Nominal strength, N. | 10.20.6 |
| $R_n$ | Nominal slip resistance, N. | 10.10.3.8 |
| $R_{pc}$ | Web plastification factor | 10.6.4.1 |
| $R_{PJP}$ | Reduction factor for reinforced or unreinforced transverse
partial-joint-penetration (PJP) groove welds | 10.17.3 |
| $R_{pt}$ | Web plastification factor corresponding to the tension flange
yielding limit state | 10.6.4.4 |
| $R_t$ | Ratio of the expected tensile strength to the specified minimum | 10.20.6 |
| $R_t$ | tensile strength $F_u$, as related to overstrength in material yield
stress $R_y$ | |
| $R_u$ | Required strength (LRFD) | 10.2.3.3 |
| $R_u$ | Required strength | 10.20.9 |
| $R_v$ | Panel zone nominal shear strength | 10.20.9 |
| $R_{wl}$ | Total nominal strength of longitudinally loaded fillet welds, as
determined in accordance with Table 6.10.8 | 10.10.2.4 |
| $R_{wt}$ | Total nominal strength of transversely loaded fillet welds, as | 10.10.2.4 |
| $R_{wt}$ | determined in accordance with Table 6.10.8 without the
alternate in Sec 10.10.2.4 (a) | |
| $R_y$ | Ratio of the expected yield stress to the specified minimum
yield stress, % | 10.20.6 |
| $S$ | Elastic section modulus of round HSS, mm3 | 10.6.8.2 |
| $S$ | Lowest elastic section modulus relative to the axis of bending,
mm3 | 10.6.12 |
| $S$ | Chord elastic section modulus, mm3 | 10.11.2.2 |
| $S$ | Spacing of secondary members, m | 10.16.1 |
| $S_c$ | Elastic section modulus to toe in compression relative to axis
of bending, mm3. | 10.6.10.3 |
| $S_{eff}$ | Effective section modulus about major axis, mm3 | 10.6.7.2 |
| $S_{xt}, S_{xc}$ | Elastic section modulus referred tension and compression
flanges, respectively, mm3 | Table 6.10.1 |
| $S_x, S_y$ | Elastic section modulus taken about the principal axes, mm3 | 10.6.2.2, F6 |
| $S_y$ | For channels, taken as the minimum section modulus | 10.6.6 |
| $T$ | Nominal forces and deformations due to design-basis fire
defined in Sec 4.2.1 | 10.18.1.4 |
| $T_a$ | Tension force due to ASD load combinations, kN. | 10.10.3.9 |
| $T_b$ | Minimum fastener tension given in Table 6.10.9, kN. | 10.10.3.8 |
| $T_c$ | Available torsional strength, N-mm. | 10.8.3.2 |
| $T_n$ | Nominal torsional strength, N-mm. | 10.8.3.1 |
| $T_r$ | Required torsional strength, N-mm. | 10.8.3.2 |
| $T_u$ | Tension force due to LRFD load combinations, kN. | 10.10.3.9 |
| $U$ | Shear lag factor | 10.4.3.3 |
| $U$ | Utilization ratio | 10.11.2.2 |
| $U_{bs}$ | Reduction coefficient, used in calculating block shear rupture
strength | 10.10.4.3 |
| $U_p$ | Stress index | 10.16.2 |
| $U_s$ | Stress index | 10.16.2 |
| $V_a$ | Required shear strength using ASD load combinations, N. | 10.20.9 |
| $V_c$ | Available shear strength, N. | 10.7.3.3 |
| $V_n$ | Nominal shear strength, N. | 10.7.1 |
| $V_n$ | Nominal shear strength of a member, N. | 10.20.15 |
| $V_p$ | Nominal shear strength of an active link, N. | Table 6.10.8 |
| $V_{pa}$ | Nominal shear strength of an active link modified by axial load
magnitude, N. | 10.20.15 |
| $V_{ne}$ | Expected vertical shear strength of the special segment, N. | 10.20.12 |
| $V_r$ | Required shear strength at the location of the stiffener, N. | 10.7.3.3 |
| $V_r$ | Required shear strength using LRFD or ASD load
combinations, N. | 10.8.3.2 |
| $V_u$ | Required shear strength using LRFD load combinations, N. | 10.20.10 |
| $Y_i$ | Gravity load from the LRFD load combination or 1.6 times
the ASD load combination Applied at level $i$, N. | 10.3.2.2 |
| $Y_t$ | Hole reduction coefficient, N. | 10.6.13.1 |
| $Z$ | Plastic section modulus about the axis of bending, mm3 | 10.6.7.1 |
| *Z* | Plastic section modulus of a member, mm3. | 10.20.9 |
| $Z_b$ | Branch plastic section modulus about the correct axis of
bending, mm3 | 10.11.3.3 |
| $Z_b$ | Plastic section modulus of the beam, mm3. | 10.20.9 |
| $Z_c$ | Plastic section modulus of the column, mm3. | 10.20.9 |
| $Z_x$ | Plastic section modulus $x$-axis, mm3. | 10.20.8 |
| $Z_{RBS}$ | Minimum plastic section modulus at the reduced beam section,
mm3. | 10.20.9 |
| $Z_{x,y}$ | Plastic section modulus about the principal axes, mm3 | 10.6.2, F6.1 |
| $a$ | Shortest distance from edge of pin hole to edge of member
measured parallel to direction of force, mm. | 10.4.5.1 |
| $a$ | Distance between connectors in a built-up member, mm. | 10.5.6.1 |
| $a$ | Clear distance between transverse stiffeners,mm. | 10.6.13.2 |
| $a$ | Half the length of the non-welded root face in the direction of
the thickness of the tension-loaded plate, mm. | 10.17.3 |
| *a* | Angle that diagonal members make with the horizontal | 10.20.12 |
| $a_w$ | Ratio of two times the web area in compression due to
Application of major axis bending moment alone to the area of
the compression flange components | 10.6.4.2 |
| $b$ | Width of unstiffened compression element; for flanges of
I-shaped members and tees, the width $b$ is half the full-flange
width, $b_f$; for legs of angles and flanges of channels and zees,
the width $b$ is the full nominal dimension; for plates, the width
$b$ is the distance from free edge to the first row of fasteners or
line of welds, or the distance between adjacent lines of fasteners
or lines of welds; for rectangular HSS, width $b$ is the clear
distance between the webs less the inside corner radius on each
side, mm. | 10.2.4.1,
10.2.4.2 |
| $b$ | Full width of longest angle leg, mm. | 10.5.7.1 |
| $b$ | Outside width of leg in compression, mm. | 10.6.10.3 |
| $b$ | Width of the angle leg resisting the shear force, mm. | 10.7.4 |
| *b* | Width of compression element as defined in Specification Sec
10.2.4.1, mm. | Table 6.10.8 |
| $b_{cf}$ | Width of column flange, mm. | 10.10.10.6 |
| $b_{cf}$ | Width of column flange, mm. | 10.20.9 |
| $b_e$ | Reduced effective width,mm. | 10.5.7.2 |
| $b_{eff}$ | Effective edge distance; the distance from the edge of the hole to the edge of the part measured in the direction normal to the applied force, mm. | 10.4.5.1 |
| $b_{eoi}$ | Effective width of the branch face welded to the chord | 10.11.2.3 |
| $b_{eov}$ | Effective width of the branch face welded to the overlapped
brace. | 10.11.2.3 |
| $b_f$ | Flange width, mm. | 10.2.4.1 |
| $b_f$ | Flange width, mm. | 10.20.9 |
| $b_{fc}$ | Compression flange width, mm. | 10.6.4.2 |
| $b_{ft}$ | Width of tension flange, mm. | 10.7.3.1 |
| $b_l$ | Longer leg of angle, mm. | 10.5.5 |
| $b_s$ | Shorter leg of angle, mm. | 10.5.5 |
| $b_s$ | Stiffener width for one-sided stiffeners, mm. | 10.19.2 |
| $d$ | Full nominal depth of section, mm. | 10.2.4.1 |
| $d$ | Pin diameter,mm. | 10.4.5.1 |
| $d$ | Full nominal depth of tee, mm. | 10.5.7.1 |
| $d$ | Depth of rectangular bar, mm. | 10.6.11.2 |
| $d$ | Nominal fastener diameter, mm. | 10.10.3.3 |
| $d$ | Diameter, mm. | 10.10.7 |
| $d$ | Roller diameter,mm. | 10.10.7 |
| *d* | Nominal fastener diameter, mm. | 10.20.7 |
| *d* | Overall beam depth, mm. | 10.20.15 |
| $d_b$ | Beam depth,mm. | 10.10.10.6 |
| $d_b$ | Nominal diameter (body or shank diameter), mm. | 10.17.4 |
| $d_c$ | Column depth, mm. | 10.10.10.6 |
| $d_c$ | Overall column depth, mm. | 10.20.9 |
| $d_z$ | Overall panel zone depth between continuity plates, mm. | 10.20.9 |
| $e$ | Eccentricity in a truss connection, positive being away from
the branches, mm. | 10.11.2.1 |
| *e* | EBF link length, mm. | 10.20.15 |
| $f_a$ | Required axial stress at point of consideration of LRFD or ASD
load combinations, MPa. | 10.8.2 |
| $f_{b(w,z)}$ | Required flexural stress at the point of consideration (major
axis, minor axis) using LRFD or ASD load combinations, MPa. | 10.8.2 |
| $f_{cm}'$ | Specified minimum compressive strength of concrete at
elevated temperatures, MPa. | 10.18.2 |
| $f_o$ | Stress due to D + R (the nominal dead load + the nominal load | 10.16.2 |
| $f_o$ | due to rainwater or snow exclusive of the ponding contribution,
MPa. | |
| $f_v$ | Required shear strength per unit area, MPa. | 10.10.3.7 |
| $g$ | Transverse center-to-center spacing (gage) between fastener
gage lines, mm. | 10.2.3.13 |
| $g$ | Gap between toes of branch members in a gapped K-
connection, neglecting welds, mm. | 10.11.2.1 |
| $h$ | Clear distance between flanges less the fillet or corner radius
for rolled shapes; for built-up sections, the distance between
adjacent lines of fasteners or the clear distance between
flanges when welds are used; for tees, the overall depth; for
rectangular HSS, the clear distance between the flanges less
the inside corner radius on each side, mm. | 10.2.4.2,
Table 6.10.8 |
| $h$ | Distance between centroids of individual components
perpendicular to the member axis of buckling,mm. | 10.5.6.1 |
| *h* | Distance between horizontal boundary element centerlines,
mm. | 10.20.17 |
| $h_c$ | Twice the distance from the centroid to the following: the inside face of the compression flange less the fillet or corner radius, for rolled shapes; the nearest line of fasteners at the compression flange or the inside faces of the compression flange when welds are used, for built-up sections, mm. | 10.2.4.2 |
| $h_o$ | Distance between flange centroids, mm. | 10.6.2.2 |
| $h_o$ | Distance between flange centroids, mm | 10.20.9 |
| $h_p$ | Twice the distance from plastic neutral axis to the nearest line | 10.2.4.2 |
| $h_p$ | of fasteners at the compression flange or inside face of
compression flange when welds are used, mm | |
| $h_{sc}$ | Hole factor | 10.10.3.8 |
| $j$ | Factor defined by Eq. 6.10.141 for minimum moment of inertia
for a transverse stiffener | 10.7.2.2 |
| $k$ | Distance from outer face of flange to the web toe of fillet, mm. | 10.10.10.2 |
| $k$ | Outside corner radius of HSS, which is permitted to be taken as
1.5$t$ if unknown, mm. | 10.11.1.3 |
| $k_c$ | Coefficient for slender unstiffened elements, mm. | Table 6.10.1 |
| $k_s$ | Slip-critical combined tension and shear coefficient | 10.10.3.9 |
| $k_v$ | Web plate buckling coefficient | 10.7.2.1 |
| $l$ | Largest laterally unbraced length along either flange at the point
of load, mm. | 10.10.10.4 |
| $l$ | Length of bearing,mm. | 10.10.7 |
| $l$ | Length of connection in the direction of loading,mm. | Table 6.10.2 |
| *l* | Unbraced length between stitches of built-up bracing
members,mm. | 10.20.13 |
| *l* | Unbraced length of compression or bracing member, mm. | 10.20.13 |
| $n$ | Number of nodal braced points within the span | 10.19.2 |
| $n$ | Threads per mm. | 10.17.4 |
| $p$ | Ratio of element $i$ deformation to its deformation at maximum
stress | 10.10.2.4 |
| $p$ | Projected length of the overlapping branch on the chord | 10.11.2.2 |
| $q$ | Overlap length measured along the connecting face of the chord
beneath the two branches | 10.11.2.2 |
| $r$ | Governing radius of gyration, mm. | 10.5.2 |
| *r* | Governing radius of gyration, mm. | 10.20.13 |
| $r_{crit}$ | Distance from instantaneous center of rotation to weld
element with minimum $\Delta_u/r_i$ ratio, mm. | 10.10.2.4 |
| $r_i$ | Minimum radius of gyration of individual component in a built-
up member, mm. | 10.5.6.1 |
| $r_{ib}$ | Radius of gyration of individual component relative to its
centroidal axis parallel to member axis of buckling, mm. | 10.5.6.1 |
| $\bar{r}_o$ | Polar radius of gyration about the shear center,mm. | 10.5.4 |
| $r_t$ | Radius of gyration of the flange components in flexural
compression plus one-third of the web area in compression due
to application of major axis bending moment alone | 10.6.4.2 |
| $r_{ts}$ | Effective radius of gyration used in the determination of $L_r$ for | 10.6.2.2 |
| $r_{ts}$ | the lateral-torsional buckling limit state for major axis bending
of doubly symmetric compact I-shaped members and channels | |
| $r_x$ | Radius of gyration about geometric axis parallel to connected
leg, mm. | 10.5.5 |
| $r_y$ | Radius of gyration about y-axis, mm. | 10.5.4 |
| $r_y$ | Radius of gyration about $y$-axis, mm. | 10.20.9 |
| $r_z$ | Radius of gyration for the minor principal axis, mm. | 10.5.5 |
| $s$ | Longitudinal center-to-center spacing (pitch) of any two
consecutive holes, mm. | 10.2.3.13 |
| $t$ | Thickness of element, mm. | 10.2.4.2 |
| *t* | Thickness of element, mm. | Table 6.10.8 |
| $t$ | Wall thickness, mm. | 10.5.7.2 |
| $t$ | Angle leg thickness, mm. | 10.6.10.2 |
| $t$ | Width of rectangular bar parallel to axis of bending, mm. | 10.6.11.2 |
| $t$ | Thickness of connected material, mm. | 10.10.3.10 |
| $t$ | Thickness of plate, mm. | 10.4.5.1 |
| $t$ | Design wall thickness for HSS equal to 0.93 times the nominal wall thickness for ERW HSS and equal to the nominal wall thickness for SAW HSS, mm. | 10.2.3.12 |
| $t$ | Total thickness of fillers, mm. | 10.10.5 |
| *t* | Thickness of connected part, mm. | 10.20.7 |
| *t* | Thickness of column web or doubler plate, mm. | 10.20.9 |
| $t$ | Design wall thickness of HSS main member, mm. | 10.11.3.1 |
| $t$ | Design wall thickness of HSS main member, mm. | 10.11.2.1 |
| $t$ | Design wall thickness of HSS member, mm. | 10.11.1.1 |
| $t_b$ | Design wall thickness of HSS branch member, mm. | 10.11.2.1 |
| $t_b$ | Design wall thickness of HSS branch member, mm. | 10.11.3.1 |
| $t_{bf}$ | Thickness of beam flange, mm. | 10.20.9 |
| $t_{bj}$ | Thickness of the overlapped branch,mm. | 10.11.2.3 |
| $t_{cf}$ | Thickness of the column flange,mm. | 10.10.10.6 |
| $t_{cf}$ | Thickness of column flange, mm. | 10.20.9 |
| $t_f$ | Thickness of the loaded flange, mm. | 10.10.10.1 |
| $t_f$ | Thickness of flange, mm. | 10.20.17 |
| $t_{fc}$ | Compression flange thickness, mm. | 10.6.4.2 |
| $t_p$ | Thickness of plate, mm. | 10.11.1.1 |
| $t_p$ | Thickness of the attached transverse plate, mm. | 10.11.2.3 |
| $t_p$ | Thickness of tension loaded plate, mm. | 10.17.3 |
| $t_p$ | Thickness of panel zone including doubler plates, mm. | 10.20.9 |
| $t_s$ | Web stiffener thickness, mm. | 10.19.2 |
| $t_w$ | Web thickness, mm. | Table 6.10.1 |
| $t_w$ | Thickness of web, mm. | Table6.10.8 |
| $t_w$ | Thickness of element, mm. | 10.5.7.1 |
| $t_w$ | Column web thickness, mm. | 10.10.10.6 |
| $t_w$ | Beam web thickness, mm. | 10.19.3 |
| $w$ | Width of cover plate, mm. | 10.6.13.3 |
| $w$ | Weld leg size, mm. | 10.10.2.2 |
| $w$ | Plate width, mm. | Table 6.10.2 |
| $w$ | Leg size of the reinforcing or contouring fillet, if any, in the
direction of the thickness of the tension-loaded plate, mm. | 10.17.3 |
| $w_z$ | Width of panel zone between column flanges, mm. | 10.20.9 |
| *x* | Parameter used for determining the approximate fundamental
period | Appendix P.2 |
| $x_o,y_o$ | Coordinates of the shear center with respect to the centroid,
mm. | 10.5.4 |
| $\bar{x}$ | Connection eccentricity,mm. | Table 6.10.2 |
| $y$ | Subscript relating symbol to weak axis | |
| $z$ | Subscript relating symbol to minor principal axis bending | |
| $Z_b$ | Minimum plastic section modulus at the reduced beam section,
mm3 | 10.20.9 |
| $\alpha$ | Factor used in Eq. 6.10.2.2 | 10.3.2.1 |
| $\alpha$ | Separation ratio for built-up compression members $=h/(2r_{ib})$ | 10.5.6.1 |
| $\alpha$ | Angle of diagonal members with the horizontal | 10.20.12 |
| $\alpha$ | Angle of web yielding in radians, as measured relative to the
vertical | 10.20.17 |
| $\beta$ | Reduction factor given by Eq. 6.10.159 | 10.10.2.2 |
| $\beta$ | The width ratio; the ratio of branch diameter to chord diameter | 10.11.2.1, |
| $\beta$ | $= D_b/D$ for round HSS; the ratio of overall branch width to
chord width $= B_b/B$ for rectangular HSS | 10.11.3.1 |
| $\beta$ | Compression strength adjustment factor | 10.20.16 |
| $\beta_T$ | Brace stiffness requirement excluding web distortion,
N-mm/radian. | 10.19.2 |
| $\beta_{br}$ | Required brace stiffness | 10.19.2 |
| $\beta_{eff}$ | Effective width ratio; the sum of the perimeters of the two
branch members in a K-connection divided by eight times the
chord width | 10.11.2.1 |
| $\beta_{eop}$ | Effective outside punching parameter | 10.11.2.3 |
| $\beta_{sec}$ | Web distortional stiffness, including the effect of web
transverse stiffeners, if any, N-mm/radian. | 10.19.2 |
| $\beta_w$ | Section property for unequal leg angles, positive for short legs
in compression and negative for long legs in compression | 10.6.10.2 |
| $\Delta$ | First-order interstory drift due to the design loads,mm. | 10.3.2.2 |
| $\Delta$ | Design story drift | 10.20.15 |
| $\Delta_b$ | Deformation quantity used to control loading of test specimen
(total brace end rotation for the sub-assemblage test specimen;
total brace axial deformation for the brace test specimen) | Appendix R.2 |
| $\Delta_{bm}$ | Value of deformation quantity, $\Delta_b$, corresponding to the
design story drift | Appendix R.6 |
| $\Delta_{by}$ | Value of deformation quantity, $\Delta_b$, at first significant yield of
test specimen | Appendix R.6 |
| $\Delta_h$ | First-order interstory drift due to lateral forces,mm. | 10.3.2.1 |
| $\Delta_i$ | Deformation of weld elements at intermediate stress levels,
linearly proportioned to the critical deformation based on
distance from instantaneous center of rotation, $r_i$, mm. | 10.10.2.4 |
| $\Delta_m$ | Deformation of weld element at maximum stress,mm. | 10.10.2.4 |
| $\Delta_u$ | Deformation of weld element at ultimate stress (fracture),
usually in element furthest from instantaneous center of
rotation, mm. | 10.10.2.4 |
| $\delta$ | Deformation quantity used to control loading of test specimen | Appendix Q.6 |
| $\delta_y$ | Value of deformation quantity $\delta$ at first significant yield of test
specimen | Appendix Q.6 |
| $\rho'$ | Ratio of required axial force $P_u$ to required shear strength $V_u$
of a link | 10.20.15 |
| $\gamma$ | The chord slenderness ratio; the ratio of one-half the diameter
to the wall thickness $=D/(2t)$ for round HSS; the ratio of one-
half the width to wall thickness $=B/(2t)$ for rectangular HSS | 10.11.2.1,
10.11.3.1 |
| $\xi$ | The gap ratio; the ratio of the gap between the branches of a
gapped K-connection to the width of the chord = g/ B for
rectangular HSS | 10.11.2.1 |
| $\eta$ | The load length parameter, applicable only to rectangular
HSS; the ratio of the length of contact of the branch with the
chord in the plane of the connection to the chord width
$=N/B$, where $N = H_b/\sin\theta$ | 10.11.2.1,
10.11.3.1 |
| $\lambda$ | Slenderness parameter | 10.6.3 |
| $\lambda_p$ | Limiting slenderness parameter for compact element | 10.2.4 |
| $\lambda_{pf}$ | Limiting slenderness parameter for compact flange | 10.6.3 |
| $\lambda_{pw}$ | Limiting slenderness parameter for compact web | 10.6.4 |
| $\lambda_r$ | Limiting slenderness parameter for noncompact element | 10.2.4 |
| $\lambda_{rf}$ | Limiting slenderness parameter for noncompact flange | 10.6.3 |
| $\lambda_{rw}$ | Limiting slenderness parameter for noncompact web | 10.6.4 |
| $\lambda_p,\lambda_{ps}$ | Limiting slenderness parameter for compact element | 10.20.8 |
| $\mu$ | Mean slip coefficient for class A or B surfaces, as Applicable,
or as established by tests | 10.10.3.8 |
| $\phi$ | Resistance factor | 10.2.3.3 |
| $\phi$ | Resistance factor | 10.20.6 |
| $\phi_b$ | Resistance factor for flexure | 10.6.1 |
| $\phi_b$ | Resistance factor for flexure | 10.20.8 |
| $\phi_c$ | Resistance factor for compression | 10.5.1 |
| $\phi_c$ | Resistance factor for compression | 10.20.8 |
| $\phi_{sf}$ | Resistance factor for shear on the failure path | 10.4.5.1 |
| $\phi_T$ | Resistance factor for torsion | 10.8.3.1 |
| $\phi_t$ | Resistance factor for tension | 10.4.2 |
| $\phi_v$ | Resistance factor for shear | 10.7.1 |
| $\phi_v$ | Resistance factor for shear strength of panel zone of beam-
to-column connections | 10.20.9 |
| $\phi_v$ | Resistance factor for shear | 10.20.15 |
| $\phi_{total}$ | Link rotation angle | Appendix Q.2 |
| $\Omega$ | Safety factor | 10.2.3.4 |
| $\Omega$ | Safety factor | 10.20.6 |
| $\Omega_b$ | Safety factor for flexure | 10.6.1 |
| $\Omega_b$ | Safety factor for flexure = 1.67 | 10.20.8 |
| $\Omega_c$ | Safety factor for compression | 10.5.1 |
| $\Omega_c$ | Safety factor for compression = 1.67 | 10.20.8 |
| $\Omega_{sf}$ | Safety factor for shear on the failure path | 10.4.5.1 |
| $\Omega_T$ | Safety factor for torsion | 10.8.3.1 |
| $\Omega_t$ | Safety factor for tension | 10.4.2 |
| $\Omega_v$ | Safety factor for shear | 10.7.1 |
| $\Omega_v$ | Safety factor for shear strength of panel zone of beam-to-
column connections | 10.20.9 |
| $\Omega_o$ | Horizontal seismic overstrength factor | 10.20.4 |
| $\theta$ | Angle of loading measured from the weld longitudinal axis,
degrees | 10.10.2.4 |
| $\theta$ | Acute angle between the branch and chord, degrees | 10.11.2.1 |
| $\theta$ | Acute angle between the branch and chord, degrees | 10.11.3.1 |
| $\theta$ | Interstory drift angle, radians | Appendix Q.3 |
| $\omega$ | Strain hardening adjustment factor | 10.20.16 |
| $\varepsilon_{cu}$ | Strain corresponding to compressive strength of concrete, $f_c'$ | 10.18.2 |
| $\tau_b$ | Parameter for reduced flexural stiffness using the direct
analysis method | 10.14.3 |
| Σ∗ | Moment at beam and column centerline determined by
projecting the sum of the nominal column plastic moment
strength, reduced by the axial stressH/, from the top and
bottom of the beam moment connection | 10.20.9 |
| Σ∗ | Moment at the intersection of the beam and column centerlines
determined by projecting the beam maximum developed
moments from the column face. Maximum developed
moments shall be determined from test results | 10.20.9 |
#### 10.1.2.2 **Definitions**
| ACTIVE FIRE PROTECTION | Building materials and systems that are activated by
a fire to mitigate adverse effects or to notify people
to take some action to mitigate adverse effects. |
| ------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| ADJUSTED BRACE STRENGTH | Strength of a brace in a buckling-restrained braced
frame at deformations corresponding to 2.0 times
the design story drift. |
| ALLOWABLE STRENGTH\* | Nominal strength divided by the safety factor,
J/Ω. |
| ALLOWABLE STRESS | Allowable strength divided by the appropriate
section property, such as section modulus or cross-
section area. |
| AMPLIFICATION FACTOR | Multiplier of the results of first-order analysis to
reflect second-order effects. |
| AMPLIFIED SEISMIC LOAD | Horizontal component of earthquake load
multiplied byΩF, whereand the horizontal
component ofare specified in the Code. |
| APPLICABLE BUILDING
CODE | Building Code under which the structure is
designed. |
| ASD(ALLOWABLE STRENGTH
DESIGN) | Method of proportioning structural components
such that the allowable strength equals or exceeds
the required strength of the component under the
action of the ASD load combinations. |
| ASD LOAD COMBINATION | Load combination in the Code intended for
allowable strength design (allowable stress design). |
| AUTHORITY HAVING
JURISDICTION | Organization, political subdivision, office or
individual charged with the responsibility of
administering and enforcing the provisions of the
Code. |
| AVAILABLE STRENGTH\* | Design
strength
or
allowable
strength,
as
appropriate. |
| AVAILABLE STRESS\* | Design stress or allowable stress, as appropriate. |
| AVERAGE RIB WIDTH | Average width of the rib of a corrugation in a
formed steel deck. |
| AUTHORITY HAVING
JURISDICTION (AHJ) | Organization, political subdivision, office or
individual charged with the responsibility of
administering and enforcing the provisions of this
Code. |
| BATTEN PLATE | Plate rigidly connected to two parallel components
of a built-up column or beam designed to transmit
shear between the components. |
| BEAM | Structural member that has the primary function of
resisting
bending
moments.
Beam-column.
Structural member that resists both axial force and
bending moment. Bearing. In a bolted connection,
limit state of shear forces transmitted by the bolt to
the connection elements. |
| BEARING (LOCAL
COMPRESSIVE YIELDING) | Limit state of local compressive yielding due to the
action of a member bearing against another
member or surface. |
| BEARING-TYPE CONNECTION | Bolted connection where shear forces are
transmitted by the bolt bearing against the
connection elements. |
| BLOCK SHEAR RUPTURE | In a connection, limit state of tension fracture along
one path and shear yielding or shear fracture along
another path. |
| BRACED FRAME | An essentially vertical truss system that provides
resistance to lateral forces and provides stability for
the structural system. |
| BRANCH FACE | Wall of HSS branch member. |
| BRANCH MEMBER | For HSS connections, member that terminates at a
chord member or main member. |
| BUCKLING | Limit state of sudden change in the geometry of a
structure or any of its elements under a critical
loading condition. |
| BUCKLING STRENGTH | Nominal strength for buckling or instability limit
states. |
| BUCKLING-RESTRAINED
BRACED FRAME (BRBF) | Diagonally
braced
frame
safisfying
the
requirements of Section16 in which all members of
the bracing system are subjected primarily to axial
forces and in which the limit state of compression
buckling of braces is precluded at forces and
deformations corresponding to 2.0 times the design
story drift. |
| BUCKLING-RESTRAINING
SYSTEM | System of restraints that limits buckling of the steel
core in BRBF. This system includes the casing on
the steel core and structural elements adjoining its
connections. The buckling-restraining system is
intended to permit the transverse expansion and
longitudinal contraction of the steel core for
deformations corresponding to 2.0 times the design
story drift. |
| BUILT-UP MEMBER, CROSS-
SECTION, SECTION, SHAPE | Member, cross-section, section or shape fabricated
from structural steel elements that are welded or
bolted together. |
| CAMBER | Curvature fabricated into a beam or truss so as to
compensate for deflection induced by loads. |
| CASING | Element that resists forces transverse to the axis of
the brace there by restraining buckling of the core.
The casing requires a means of delivering this force
to the remainder of the buckling-restraining system.
The casing resists little or no force in the axis of the
brace. |
| CHARPY V-NOTCH IMPACT
TEST | Standard dynamic test measuring notch toughness
of a specimen. |
| CHORD MEMBER | For HSS, primary member that extends through a
truss connection. |
| CLADDING | Exterior covering of structure. |
| COLD-FORMED STEEL
STRUCTURAL MEMBER | Shape manufactured by press-braking blanks
sheared from sheets, cut lengths of coils or plates,
or by roll forming cold-or hot-rolled coils or sheets;
both forming operations being performed at
ambient room temperature, that is, without manifest
addition of heat such as would be required for hot
forming. |
| COLUMN | Structural member that has the primary function of
resisting axial force. |
| COLUMN BASE | Assemblage of plates, connectors, bolts, and rods at
the base of a column used to transmit forces |
| | between
the
steel
superstructure
and
the
foundation. |
| COMBINED SYSTEM | Structure comprised of two or more lateral load-
resisting systems of different type. |
| COMPACT SECTION | Section capable of developing a fully plastic stress
distribution and possessing a rotation capacity of
approximately three before the onset of local
buckling. |
| COMPARTMENTATION | The enclosure of a building space with elements that
have a specific fire endurance. |
| COMPLETE-JOINT-
PENETRATION GROOVE
WELD (CJP) | Groove weld in which weld metal extends through
the joint thickness, except as permitted for HSS
connections. |
| COMPOSITE | Condition in which steel and concrete elements and
members work as a unit in the distribution of
internal forces. |
| CONCRETE CRUSHING | Limit state of compressive failure in concrete
having reached the ultimate strain. |
| CONCRETE HAUNCH | Section of solid concrete that results from stopping
the deck on each side of the girder in a composite
floor system constructed using a formed steel deck. |
| CONCRETE-ENCASED BEAM | Beam totally encased in concrete cast integrally
with the slab. |
| CONNECTION | Combination of structural elements and joints used
to transmit forces between two or more members. |
| CONVECTIVE HEAT | The transfer of thermal energy from a point of |
| TRANSFER | higher temperature to a point of lower temperature
through the motion of an intervening medium. |
| CONTINUITY PLATES | Column stiffeners at the top and bottom of the panel
zone; also known as transverse stiffeners. |
| CONTRACTOR | Fabricator or erector, as applicable. |
| COPE | Cutout made in a structural member to remove a
flange and conform to the shape of an intersecting
member. |
| COVER PLATE | Plate welded or bolted to the flange of a member to
increase cross-sectional area, section modulus or
moment of inertia. |
| CROSS CONNECTION | HSS connection in which forces in branch members
or connecting elements transverse to the main
member are primarily equilibrated by forces in
other branch members or connecting elements on
the opposite side of the main member. |
| DEMANDCRITICAL WELD | Weld so designated by these Provisions. |
| DESIGNEARTHQUAKE | The earthquake represented by the design response
spectrum as specified in the Code. |
| DESIGNSTORYDRIFT | Amplified story drift (drift under the design
earthquake, including the effects of inelastic
action), determined as specified in the Code. |
| DESIGN-BASIS FIRE | A set of conditions that define the development of
a fire and the spread of combustion products
throughout a building or portion thereof. |
| DESIGN LOAD\* | Applied load determined in accordance with either
LRFD
load
combinations
or
ASD
load
combinations, whichever is applicable. |
| DESIGN STRENGTH\* | Resistance factor multiplied by the nominal
strength,\{J. |
| DESIGN STRESS RANGE | Magnitude of change in stress due to the repeated
application and removal of service live loads. For
locations subject to stress reversal it is the algebraic
difference of the peak stresses. |
| DESIGN STRESS\* | Design strength divided by the appropriate section
property, such as section modulus or cross section
area. |
| DESIGN WALL THICKNESS | HSS wall thickness assumed in the determination
of section properties. |
| DIAGONAL BRACING | Inclined structural member carrying primarily axial
force in a braced frame. |
| DIAGONAL STIFFENER | Web stiffener at column panel zone oriented
diagonally to the flanges, on one or both sides of
the web. |
| DIAPHRAGM PLATE | Plate possessing in-plane shear stiffness and
strength, used to transfer forces to the supporting
elements. |
| DIAPHRAGM | Roof, floor or other membrane or bracing system
that transfers in-plane forces to the lateral force
resisting system. |
| DIRECT ANALYSIS METHOD | Design method for stability that captures the effects
of residual stresses and initial out-of-plumbness of
frames by reducing stiffness and applying notional
loads in a second-order analysis. |
| DIRECT BOND INTERACTION | Mechanism by which force is transferred between
steel and concrete in a composite section by bond
stress. |
| DISTORTIONAL FAILURE | Limit state of an HSS truss connection based on
distortion of a rectangular HSS chord member into
a rhomboidal shape. |
| DISTORTIONAL STIFFNESS | Out-of-plane flexural stiffness of web. |
| DOUBLE CURVATURE | Deformed shape of a beam with one or more
inflection points within the span. |
| DOUBLE-CONCENTRATED
FORCES | Two equal and opposite forces that form a couple
on the same side of the loaded member. |
| DOUBLER | Plate added to, and parallel with, a beam or column
web to increase resistance to concentrated forces. |
| DRIFT | Lateral deflection of structure. |
| DUAL SYSTEM | Structural system with the following features (1) an
essentially complete space frame that provides
support for gravity loads; (2) resistance to lateral
load provided by moment frames (SMF, IMF or
OMF) that are capable of resisting atleast 25 percent
of the base shear, and concrete or steel shearwalls,
or steel braced frames (EBF,S CBF or OCBF); and
(3) each system designed to resist the total lateral
load in proportion to its relative rigidity. |
| DUCTILE LIMIT STATE | Ductile limit states include member and connection
yielding, bearing deformation at bolt holes, as well
as buckling of members that conform to the width-
thickness limitations of Table 6.10.18. Fracture of a
member or of a connection, or buckling of a
connection element, is not a ductile limit state. |
| ECCENTRICALLY BRACED
FRAME (EBF) | Diagonally braced frame meeting there quirements
of Section 15 that has at least one end of each
bracing member connected to a beam a short
distance from another beam-to-brace connection or
a beam-to-column connection. |
| EFFECTIVE LENGTH
FACTOR, K | Ratio between the effective length and the unbraced
length of the member. |
| EFFECTIVE LENGTH | Length of an otherwise identical column with the
same strength when analyzed with pinned end
conditions. |
| EFFECTIVE NET AREA | Net area modified to account for the effect of shear
lag. |
| EFFECTIVE SECTION
MODULUS | Section modulus reduced to account for buckling of
slender compression elements. |
| EFFECTIVE WIDTH | Reduced width of a plate or slab with an assumed
uniform stress distribution which produces the
same effect on the behavior of a structural member
as the actual plate or slab width with its nonuniform
stress distribution. |
| ELASTIC ANALYSIS | Structural analysis based on the assumption that the
structure returns to its original geometry on
removal of the load. |
| ELEVATED TEMPERATURES | Heating conditions experienced by building
elements or structures as a result of fire, which are
in excess of the anticipated ambient conditions. |
| ENCASED COMPOSITE
COLUMN | Composite column consisting of a structural
concrete column and one or more embedded steel
shapes. |
| END PANEL | Web panel with an adjacent panel on one side only. |
| ENGINEER OF RECORD | Engineer having authority or license from
government approved Authority to sign and seal
engineering and contract documents. |
| END RETURN | Length of fillet weld that continues around a corner
in the same plane. Engineer of record. Licensed
professional responsible for sealing the contract
documents. Expansion rocker. Support with curved
surface on which a member bears that can tilt to
accommodate expansion. |
| EXPANSION ROLLER | Round steel bar on which a member bears that can
roll to accommodate expansion. |
| EXEMPTED COLUMN | Column not meeting the requirements of Eq.
6.10.300 for SMF. |
| EXPECTED TENSILE | Tensile strength of a member, equal to the specified |
| STRENGTH \* |
minimum tensile strength, , multiplied byJ. |
| EXPECTED YIELD STRENGTH | Yield strength in tension of a member, equal to the
expected yield stress multiplied by. |
| EXPECTED YIELD STRESS | Yield stress of the material, equal to the specified
minimum yield stress, %,multiplied byJ%. |
| EYEBAR | Pin-connected
tension
member
of
uniform
thickness, with forged or thermally cut head of
greater width than the body, proportioned to
provide approximately equal strength in the head
and body. |
| FACTORED LOAD | Product of a load factor and the nominal load.
Fastener. Generic term for bolts, rivets, or other
connecting devices. |
| FATIGUE | Limit state of crack initiation and growth resulting
from repeated application of live loads. |
| FAYING SURFACE | Contact
surface
of
connection
elements
transmitting a shear force. |
| FILLED COMPOSITE COLUMN | Composite column consisting of a shell of HSS or
pipe filled with structural concrete. |
| FILLER METAL | Metal or alloy to be added in making a welded joint.
Filler. Plate used to build up the thickness of one
component. Fillet weld reinforcement. Fillet welds
added to groove welds. |
| FILLET WELD | Weld of generally triangular cross section made
between intersecting surfaces of elements. |
| FIRE | Destructive burning, as manifested by any or all of
the following: light, flame, heat, or smoke. |
| FIRE BARRIER | Element of construction formed of fire-resisting
materials and tested in accordance with ASTM
Standard E119, or other approved standard fire
resistance test, to demonstrate compliance with the
Building Code. |
| FIRE ENDURANCE | A measure of the elapsed time during which a
material or assembly continues to exhibit fire
resistance. |
| FIRE RESISTANCE | That property of assemblies that prevents or retards
the pas- sage of excessive heat, hot gases or flames
under conditions of use and enables them to
continue to perform a stipulated function. |
| FIRE RESISTANCE RATING | The period of time a building element, component
or assembly maintains the ability to contain a fire,
continues to perform a given structural function, or
both, as determined by test or methods based on
tests. |
| FIRST-ORDER ANALYSIS | Structural analysis in which equilibrium conditions
are formulated on the undeformed structure;
second-order effects are neglected. |
| FITTED BEARING STIFFENER | Stiffener used at a support or concentrated load that
fits tightly against one or both flanges of a beam so
as to transmit load through bearing. |
| FLASHOVER | The rapid transition to a state of total surface
involvement in a fire of combustible materials
within an enclosure. |
| FLARE BEVEL GROOVE
WELD | Weld in a groove formed by a member with a
curved surface in contact with a planar member. |
| FLARE V-GROOVE WELD | Weld in a groove formed by two members with
curved surfaces. |
| FLAT WIDTH | Nominal width of rectangular HSS minus twice the
outside corner radius. In absence of knowledge of
the corner radius, the flat width may be taken as the
total section width minus three times the thickness. |
| FLEXURAL BUCKLING | Buckling mode in which a compression member
deflects laterally without twist or change in cross-
sectional shape. |
| FLEXURAL-TORSIONAL
BUCKLING | Buckling mode in which a compression member
bends and twists simultaneously without change in
cross-sectional shape. |
| FORCE | Resultant of distribution of stress over a prescribed
area. |
| FORMED SECTION | See cold-formed steel structural member. |
| FORMED STEEL DECK | In composite construction, steel cold formed into a
decking profile used as a permanent concrete form. |
| FULLY RESTRAINED
MOMENT CONNECTION | Connection capable of transferring moment with
negligible rotation between connected members. |
| GAGE | Transverse center-to-center spacing of fasteners. |
| GAP CONNECTION | HSS truss connection with a gap or space on the
chord face between intersecting branch members. |
| GENERAL COLLAPSE | Limit state of chord plastification of opposing sides |
| | of a round HSSchord member at a cross-
connection. |
| GEOMETRIC AXIS | Axis parallel to web, flange or angle leg. |
| GIRDER FILLER | Narrow piece of sheet steel used as a fill between
edge of a deck sheet and flange of a girder in a
composite floor system constructed using a formed
steel deck. |
| GIRDER | See Beam. |
| GIRT | Horizontal structural member that supports wall
panels and is primarily subjected to bending under
horizontal loads, such as wind load. |
| GOUGE | Relatively smooth surface groove or cavity
resulting from plastic deformation or removal of
material. |
| GRAVITY AXIS | Axis through the center of gravity of a member
along its length. |
| GRAVITY FRAME | Portion of the framing system not included in the
lateral load resisting system. |
| GRAVITY LOAD | Load, such as that produced by dead and live loads,
acting in the downward direction. |
| GRIP (OF BOLT) | Thickness of material through which a bolt passes. |
| GROOVE WELD | Weld in a groove between connection elements.
See also AWS D1.1. |
| GUSSET PLATE | Plate element connecting truss members or a strut
or brace to a beam or column. |
| HEAT FLUX | Radiant energy per unit surface area. |
| HEAT RELEASE RATE | The rate at which thermal energy is generated by a
burning material. |
| HORIZONTAL SHEAR | Force at the interface between steel and concrete
surfaces in a composite beam. |
| HSS | Square, rectangular or round hollow structural steel
section produced in accordance with a pipe or
tubing product specification. |
| INELASTIC ANALYSIS | Structural analysis that takes into account inelastic
material behavior, including plastic analysis. |
| IN-PLANE INSTABILITY | Limit state of a beam-column bent about its major
axis while lateral buckling or lateral-torsional
buckling is prevented by lateral bracing. |
| INSTABILITY | Limit state reached in the loading of a structural
component, frame or structure in which a slight
disturbance in the loads or geometry produces large
displacements. |
| INTERMEDIATE MOMENT
FRAME (IMF) | Moment frame system that meets the requirements
of Sec 10.20.10. |
| INTERSTORY DRIFT ANGLE | Interstory displacement divided by story height,
radians. |
| INVERTED-V-BRACED FRAME | See V-braced frame. |
| JOINT ECCENTRICITY | For HSS truss connection, perpendicular distance
from chord member center of gravity to intersection
of branch member work points. |
| JOINT | Area where two or more ends, surfaces, or edges
are attached. Categorized by type of fastener or
weld used and method of force transfer. |
| K-AREA | The\_k-area\_is the region of the web that extends
from the tangent point of the web and the flange-
web fillet (AISC “*k*” dimension) a distance of 38
mm in to the web beyond the “*k*” dimension. |
| K-BRACED FRAME | A bracing configuration in which braces connect to
a column at a location with no diaphragm or other
out-of-plane support. |
| K-CONNECTION | HSS connection in which forces in branch members
or connecting elements transverse to the main
member are primarily equilibrated by forces in
other branch members or connecting elements on
the same side of the main member. |
| KSI | Kip per square inch, a US customary unit of stress. |
| LOWEST ANTICIPATED
SERVICE TEMPERATURE
(LAST) | The lowest1-hour average temperature with a
100-year mean recurrence interval. |
| LRFD (LOAD AND
RESISTANCE FACTOR
DESIGN) | Method of proportioning structural components
such that the design strength equals or exceeds the
required strength of the component under the action
of the LRFD load combinations. |
| LRFD LOAD COMBINATION | Load combination in the Code intended for strength
design (load and resistance factor design). |
| LACING | Plate, angle or other steel shape, in a lattice
configuration, that connects two steel shapes
together. |
| LAP JOINT | Joint
between
two
overlapping
connection
elements in parallel planes. |
| LATERAL BRACING | Diagonal bracing, shear walls or equivalent means
for providing in-plane lateral stability. |
| LATERAL BRACING MEMBER | Member that is designed to inhibit lateral buckling
or lateral- torsional buckling of primary framing
members. |
| LATERAL LOAD RESISTING
SYSTEM | Structural system designed to resist lateral loads
and provide stability for the structure as a whole. |
| LATERAL LOAD | Load that produced by wind or earthquake effects,
acting in a lateral direction. |
| LATERAL-TORSIONAL
BUCKLING | Buckling mode of a flexural member involving
deflection normal to the plane of bending occurring
simultaneously with twist about shear center of the
cross-section. |
| LEANING COLUMN | Column designed to carry gravity loads only, with
connections that are not intended to provide
resistance to lateral loads. |
| LENGTH EFFECTS | Consideration of the reduction in strength of a
member based on its unbraced length. |
| LIMIT STATE | Condition in which a structure or component
becomes unfit for service and is judged either to be
no longer useful for its intended function
(serviceability limit state) or to have reached its
ultimate load-carrying capacity (strength limit
state). |
| LINK | In EBF, the segment of a beam that is located
between the ends of two diagonal braces or between
the end of a diagonal brace and a column. The
length of the link is defined as the clear distance
between the end soft wodiagonal braces or between
the diagonal brace and the column face. |
| LINK INTERMEDIATE WEB
STIFFENERS | Vertical web stiffeners placed within the link in
EBF. |
| LINK ROTATION ANGLE | Inelastic angle between the link and the beam
outside of the link when the total story drift is equal
to the design story drift. |
| LINK SHEAR DESIGN
STRENGTH | Lesser of the available shear strength of the link
developed from the moment or shear strength of the
link. |
| LOAD | Force or other action that results from the weight of
building materials, occupants and their possessions,
environmental effects, differential movement, or
restrained dimensional changes. |
| LOAD EFFECT | Forces, stresses and deformations produced in a
structural component by the applied loads. |
| LOAD FACTOR | Factor that accounts for deviations of the nominal
load from the actual load, for uncertainties in the
analysis that transforms the load into a load effect
and for the probability that more than one extreme
load will occur simultaneously. |
| LOCAL BENDING\*\* | Limit state of large deformation of a flange under a
concentrated tensile force. |
| LOCAL BUCKLING\*\* | Limit state of buckling of a compression element
within a cross section. |
| LOCAL CRIPPLING\*\* | Limit state of local failure of web plate in the
immediate vicinity of a concentrated load or
reaction. |
| LOCAL YIELDING\*\* | Yielding that occurs in a local area of an element. |
| LRFD (LOAD AND
RESISTANCE FACTOR
DESIGN) | Method of proportioning structural components
such that the design strength equals or exceeds the
required strength of the component under the action
of the LRFD load combinations. |
| LRFD LOAD COMBINATION | Load combination in the Code intended for strength
design (load and resistance factor design. |
| MAIN MEMBER | For HSS connections, chord member, column or
other HSS member to which branch members or
other connecting elements are attached. |
| MEASURED FLEXURAL
RESISTANCE | Bending moment measured in a beam at the face of
the column, for a beam-to-column test specimen
tested in accordance with Appendix S. |
| MECHANISM | Structural system that includes a sufficient
number of real hinges, plastic hinges or both, so
as to be able to articulate in one or more rigid body
modes. |
# Chapter 2: Loads on Buildings and Structures
Source: https://docs.sayed.app/bnbc/part-6-structural-design/chapter-2-loads-on-buildings-and-structures
## **2.1 Introduction**
### **2.1.1 Scope**
This Chapter specifies the minimum design forces including dead load, live load, wind and earthquake loads, miscellaneous loads and their various combinations. These loads shall be applicable for the design of buildings and structures in conformance with the general design requirements provided in Chapter 1.
### **2.1.2 Limitations**
Provisions of this Chapter shall generally be applied to majority of buildings and other structures covered in this Code subject to normally expected loading conditions. For those buildings and structures having unusual geometrical shapes, response characteristics or site locations, or for those subject to special loading including tornadoes, special dynamic or hydrodynamic loads etc., site-specific or case-specific data or analysis may be required to determine the design loads on them. In such cases, and all other cases for which loads are not specified in this Chapter, loading information may be obtained from reliable references or specialist advice may be sought. However, such loads shall be applied in compliance with the provisions of other Parts or Sections of this Code.
### **2.1.3 Terminology**
The following definitions apply only to the provisions of this Chapter:
ALLOWABLE A method for proportioning structural members such that STRESS DESIGN the maximum stresses due to service loads obtained from an METHOD (ASD) elastic analysis does not exceed a specified allowable value. This is also called Working Stress Design Method (WSD). APPROVED Acceptable to the authority having jurisdiction. BASE The level at which the earthquake motions are considered to be imparted to the structures or the level at which the structure as a dynamic vibrator is supported. BASE SHEAR Total design lateral force or shear due to earthquake at the base of a structure.
| BASIC WIND
SPEEDV\_ | Three-second gust speed at 10 m above the ground in
Exposure B (Sec 2.4.6.3) having a return period of 50 years. |
| --------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| BEARING WALL
SYSTEM | A structural system without a complete vertical load
carrying space frame. |
| BRACED FRAME | An essentially vertical truss system of the concentric or
eccentric type provided to resist lateral forces. |
| BUILDING,
ENCLOSED | A building that does not comply with the requirements for
open or partially enclosed buildings. |
| BUILDING | Cladding, roofing, exterior walls, glazing, door assemblies, |
| ENVELOPE | window assemblies, skylight assemblies, and other
components enclosing the building. |
| BUILDING, LOW-
RISE | Enclosed or partially enclosed buildings that comply with
the following conditions
1. Mean roof height\_h\_less than or equal to 18.3 m.
2. Mean roof height\_h\_does not exceed least horizontal
dimension. |
| BUILDING, OPEN | A building having each wall at least 80 percent open. This
condition is expressed for each wall by the equation≥
0.8 where,
= total area of openings in a wall that receives positive
external pressure (m2).
= the gross area of that wall in whichis identified
(m2). |
| BUILDING,
PARTIALLY | A building that complies with both of the following
conditions: |
| ENCLOSED | 1. The total area of openings in a wall that receives positive
external pressure exceeds the sum of the areas of openings
in the balance of the building envelope (walls and roof) by
more than 10 percent.
2. The total area of openings in a wall that receives positive
external pressure exceeds 0.37 m2or 1 percent of the area of
that wall, whichever is smaller, and the percentage of
openings in the balance of the building envelope does not
exceed 20 percent. |
| | These conditions are expressed by the following equations:
1.> 1.10
2.> 0.37mor > 0.01, whichever is smaller, and
/≤0.20
Where,,are as defined for open building
= the sum of the areas of openings in the building
envelope (walls and roof) not including, in m2.
= the sum of the gross surface areas of the building
envelope (walls and roof) not including, in m2. |
| BUILDING,
SIMPLE
DIAPHRAGM | A building in which both windward and leeward wind loads
are transmitted through floor and roof diaphragms to the
same vertical MWFRS (e.g., no structural separations). |
| BUILDING
FRAME SYSTEM |
An essentially complete space frame which provides
support for gravity loads. |
| BUILDING OR
OTHER
STRUCTURE,
FLEXIBLE | Slender buildings or other structures that have a
fundamental natural frequency less than 1 Hz. |
| BUILDING OR
OTHER
STRUCTURE,
REGULAR
SHAPED | A building or other structure having no unusual geometrical
irregularity in spatial form. |
| BUILDING OR
OTHER
STRUCTURES,
RIGID | A building or other structure whose fundamental frequency
is greater than or equal to 1 Hz. |
| CAPACITY
CURVE | A plot of the total applied lateral force,, versus the lateral
displacement of the control point,, as determined in a
nonlinear static analysis. |
| COMPONENTS
AND CLADDING | Elements of the building envelope that do not qualify as
part of the MWFRS. |
| CONTROL POINT |
A point used to index the lateral displacement of the
structure in a nonlinear static analysis. |
| CRITICAL
DAMPING | Amount of damping beyond which the free vibration will
not be oscillatory. |
| CYCLONE
PRONE REGIONS |
Areas vulnerable to cyclones; in Bangladesh these areas
include the Sundarbans, southern parts of Barisal and
Patuakhali, Hatia, Bhola, eastern parts of Chittagong and
Cox’s Bazar |
| DAMPING | The effect of inherent energy dissipation mechanisms in a
structure (due to sliding, friction, etc.) that results in
reduction of effect of vibration, expressed as a percentage
of the critical damping for the structure. |
| DESIGN | Smoothened idealized plot of maximum acceleration of a |
| ACCELERATION
RESPONSE
SPECTRUM | single degree of freedom structure as a function of structure
period for design earthquake ground motion. |
| DESIGN
EARTHQUAKE | The earthquake ground motion considered (for normal
design) as two-thirds of the corresponding Maximum
Considered Earthquake (MCE). |
| DESIGN FORCE, | *F* Equivalent static force to be used in the determination of
wind loads for open buildings and other structures. |
| DESIGN
PRESSUREp\_ | Equivalent static pressure to be used in the determination of
wind loads for buildings. |
| DESIGN
STRENGTH | The product of the nominal strength and a resistance factor. |
| DIAPHRAGM | A horizontal or nearly horizontal system of structures acting
to transmit lateral forces to the vertical resisting elements.
The term "diaphragm" includes reinforced concrete floor
slabs as well as horizontal bracing systems. |
| DUAL SYSTEM | A combination of a Special or Intermediate Moment
Resisting Frame and Shear Walls or Braced Frames
designed in accordance with the criteria of Sec 1.3.2.4 |
| DUCTILITY | Capacity of a structure, or its members to undergo large
inelastic deformations without significant loss of strength or
stiffness. |
| EAVE HEIGHTh\_ | The distance from the ground surface adjacent to the
building to the roof eave line at a particular wall. If the
height of the eave varies along the wall, the average height
shall be used. |
| ECCENTRIC
BRACED FRAME
(EBF) |
A steel braced frame designed in conformance with Sec
10.20.15. |
| EFFECTIVE
WIND AREAA\_ | The area used to determine\_GCp\_. For component and
cladding elements, the effective wind area as mentioned in
Sec 2.4.11 is the span length multiplied by an effective
width that need not be less than one-third the span length.
For cladding fasteners, the effective wind area shall not be
greater than the area that is tributary to an individual
fastener. |
| EPICENTRE | The point on the surface of earth vertically above the focus
(point of origin) of the earthquake. |
| ESCARPMENT | Also known as scarp, with respect to topographic effects in
Sec 2.4.7, a cliff or steep slope generally separating two
levels or gently sloping areas (see Figure 6.2.4). |
| ESSENTIAL | Buildings and structures which are necessary to remain |
| FACILITIES | functional during an emergency or a post disaster period. |
| FACTORED
LOAD | The product of the nominal load and a load factor. |
| FLEXIBLE
DIAPHRAGM | A floor or roof diaphragm shall be considered flexible, for
purposes of this provision, when the maximum lateral
deformation of the diaphragm is more than two times the
average storey drift of the associated storey. This may be
determined by comparing the computed midpoint in-plane
deflection of the diaphragm under lateral load with the
storey drift of adjoining vertical resisting elements under
equivalent tributary lateral load. |
| FLEXIBLE | An element or system whose deformation under lateral load |
| ELEMENT OR
SYSTEM | is significantly larger than adjoining parts of the system. |
| FREE ROOF | Roof (monoslope, pitched, or troughed) in an open building
with no enclosing walls underneath the roof surface. |
| GLAZING | Glass or transparent or translucent plastic sheet used in
windows, doors, skylights, or curtain walls. |
| GLAZING,
IMPACT
RESISTANT | Glazing that has been shown by testing in accordance with
ASTM E1886 and ASTM E1996 or other approved test
methods to withstand the impact of wind-borne missiles
likely to be generated in wind-borne debris regions during
design winds. |
| HILL | With respect to topographic effects in Sec 2.4.7, a land
surface characterized by strong relief in any horizontal
direction (Figure 6.2.4). |
| HORIZONTAL
BRACING
SYSTEM | A horizontal truss system that serves the same function as a
floor or roof diaphragm. |
| IMPACT
RESISTANT
COVERING | A covering designed to protect glazing, which has been
shown by testing in accordance with ASTM E1886 and
ASTM E1996 or other approved test methods to withstand
the impact of wind-borne debris missiles likely to be
generated in wind-borne debris regions during design
winds. |
| IMPORTANCE
FACTOR, WIND
LOAD | A factor that accounts for the degree of hazard to human
life and damage to property. |
| IMPORTANCE
FACTOR,
EARTHQUAKE
LOAD | It is a factor used to increase the design seismic forces for
structures of importance. |
| INTENSITY OF
EARTHQUAKE | It is a measure of the amount of ground shaking at a
particular site due to an earthquake |
| INTERMEDIATE
MOMENT
FRAME (IMF) | A concrete or steel frame designed in accordance with Sec
8.3.10 or Sec 10.20.10 respectively. |
| LIMIT STATE | A condition in which a structure or component becomes
unfit for service and is judged either to be no longer useful
for its intended function (serviceability limit state) or to be
unsafe (strength limit state). |
| LIQUEFACTION | State in saturated cohesionless soil wherein the effective
shear strength is reduced to negligible value due to pore
water pressure generated by earthquake vibrations, when
the pore water pressure approaches the total confining
pressure. In this condition, the soil tends to behave like a
liquid. |
| LOAD EFFECTS | Forces, moments, deformations and other effects produced
in structural members and components by the applied loads. |
| LOAD FACTOR | A factor that accounts for unavoidable deviations of the
actual load from the nominal value and for uncertainties in
the analysis that transforms the load into a load effect. |
| LOADS | Forces or other actions that arise on structural systems from
the weight of all permanent constructions, occupants and
their
possessions,
environmental
effects,
differential
settlement, and restrained dimensional changes. Permanent
loads are those loads in which variations in time are rare or
of small magnitude. All other loads are variable loads. |
| MAGNITUDE OF
EARTHQUAKE | The magnitude of earthquake is a number, which is a
measure of energy released in an earthquake. |
| MAIN WIND-
FORCE
RESISTING
SYSTEM
(MWFRS) | An assemblage of structural elements assigned to provide
support and stability for the overall structure. The system
generally receives wind loading from more than one
surface. |
| MAXIMUM
CONSIDERED
EARTHQUAKE
(MCE) | The most severe earthquake ground motion considered by
this Code. |
| MEAN ROOF
HEIGHTh\_ | The average of the roof eave height and the height to the
highest point on the roof surface, except that, for roof
angles of less than or equal to 10o, the mean roof height
shall be the roof heave height. |
| MODAL MASS | Part of the total seismic mass of the structure that is
effective in mode k of vibration. |
| MODAL
PARTICIPATION
FACTOR | Amount by which mode k contributes to the overall
vibration of the structure under horizontal and vertical
earthquake ground motions. |
| MODAL SHAPE
COEFFICIENT | When a system is vibrating in a normal mode, at any
particular instant of time, the vibration amplitude of mass
expressed as a ratio of the vibration amplitude of one of
the masses of the system, is known as modal shape
coefficient |
| MOMENT
RESISTING
FRAME | A frame in which members and joints are capable of
resisting lateral forces primarily by flexure. Moment
resisting frames are classified as ordinary moment frames
(OMF), intermediate moment frames (IMF) and special
moment frames (SMF). |
| NOMINAL
LOADS | The magnitudes of the loads such as dead, live, wind,
earthquake etc. specified in Sections 2.2 to 2.6 of this
Chapter. |
| NOMINAL
STRENGTH | The capacity of a structure or component to resist the
effects of loads, as determined by computations using
specified material strengths and dimensions and formulas
derived from accepted principles of structural mechanics or
by field tests or laboratory tests of scaled models, allowing
for modelling effects and differences between laboratory
and field conditions. |
| NUMBER OF
STOREYS (n) | Number of storeys of a building is the number of levels
above the base. This excludes the basement storeys, where
basement walls are connected with ground floor deck or
fitted between the building columns. But, it includes the
basement storeys, when they are not so connected. |
| OPENINGS | Apertures or holes in the building envelope that allow air to
flow through the building envelope and that are designed as
“open” during design winds as defined by these provisions. |
| ORDINARY
MOMENT
FRAME (OMF) | A moment resisting frame not meeting special detailing
requirements for ductile behaviour. |
| PERIOD OF
BUILDING | Fundamental period (for 1st mode) of vibration of building
for lateral motion in direction considered. |
| P-DELTA EFFEC | T
It is the secondary effect on shears and moments of frame
members due to action of the vertical loads due to the
lateral displacement of building resulting from seismic
forces. |
| RATIONAL
ANALYSIS | An analysis based on established methods or theories using
mathematical formulae and actual or appropriately assumed
data. |
| RECOGNIZED
LITERATURE | Published research findings and technical papers that are
approved. |
| RESISTANCE
FACTOR | A factor that accounts for unavoidable deviations of the
actual strength from the nominal value and the manner and
consequences of failure. This is also known as strength
reduction factor. |
| RESPONSE
REDUCTION
FACTOR | It is the factor by which the actual base shear force that
would develop if the structure behaved truly elastic during
earthquake, is reduced to obtain design base shear. This
reduction is allowed to account for the beneficial effects of
inelastic deformation (resulting in energy dissipation) that
can occur in a structure during a major earthquake, still
ensuring acceptable response of the structure. |
| RIDGE | With respect to topographic effects in Sec 2.4.7, an
elongated crest of a hill characterized by strong relief in two
directions (Figure 6.2.4). |
| SEISMIC DESIGN
CATEGORY |
A classification assigned to a structure based on its
importance factor and the severity of the design earthquake
ground motion at the site. |
| SEISMIC-FORCE-
RESISTING
SYSTEM | That part of the structural system that has been considered
in the design to provide the required resistance to the
seismic forces. |
| SHEAR WALL | A wall designed to resist lateral forces acting in its plane
(sometimes referred to as a vertical diaphragm or a
structural wall). |
| SITE CLASS | Site is classified based on soil properties of upper 30 m. |
| SITE-SPECIFIC
DATA | Data obtained either from measurements taken at a site or
from substantiated field information required specifically
for the structure concerned. |
| SOFT STOREY | Storey in which the lateral stiffness is less than 70 percent
of the stiffness of the storey above or less than 80 percent of
the average lateral stiffness of the three storeys above. |
| SPACE FRAME | A three-dimensional structural system without bearing walls
composed of members interconnected so as to function as a
complete self-contained unit with or without the aid of
horizontal diaphragms or floor bracing systems. |
| SPECIAL | A moment resisting frame specially detailed to provide |
| MOMENT | ductile behaviour complying with the seismic requirements |
| FRAME (SMF) | provided in Chapters 8 and 10 for concrete and steel frames
respectively. |
| STOREY | The space between consecutive floor levels. Storey-x is the
storey below level-x. |
| STOREY DRIFT | The horizontal deflection at the top of the story relative to
bottom of the storey. |
| STOREY SHEAR | The total horizontal shear force at a particular storey (level). |
| STRENGTH | The usable capacity of an element or a member to resist the
load as prescribed in these provisions. |
| STRENGTH
DESIGN
METHOD | A method of proportioning structural members using load
factors and resistance factors satisfying both the applicable
limit state conditions. This is also known as Load Factor
Design Method (LFD) or Ultimate Strength Design Method
(USD). |
| TARGET
DISPLACEMENT | An estimate of the maximum expected displacement of the
control point calculated for the design earthquake ground
motion in nonlinear static analysis. |
| VERTICAL LOAD-
CARRYING
FRAME | A space frame designed to carry all vertical gravity loads. |
| WEAK STOREY | Storey in which the lateral strength is less than 80 percent
of that of the storey above. |
| WIND-BORNE | Areas within cyclone prone regions located: |
| DEBRIS
REGIONS | 1. Within 1.6 km of the coastal mean high water line
where the basic wind speed is equal to or greater than
180 km/h or |
| | 2. In areas where the basic wind speed is equal to or
greater than 200 km/h. |
| WORKING
STRESS DESIGN
METHOD (WSD) | See ALLOWABLE STRESS DESIGN METHOD. |
### **2.1.4 Symbols and Notation**
The following symbols and notation apply only to the provisions of this Chapter:
* $A$ = Effective wind area, in m2
* $A_f$ = Area of open buildings and other structures either normal to the wind direction or projected on a plane normal to the wind direction, in m2.
* $A_g$ = Gross area of that wall in which $A_o$ is identified, in m2.
* $A_{gi}$ = Sum of gross surface areas of the building envelope (walls and roof) not including $A_g$, in m2
* $A_o$ = Total area of openings in a wall that receives positive external pressure, in m2.
* $A_{oi}$ = Sum of the areas of openings in the building envelope (walls and roof) not including $A_o$, in m2
* $A_{og}$ = Total area of openings in the building envelope in m2
* $A_s$ = Gross area of the solid freestanding wall or solid sign, in m2
* $A_x$ = Torsion amplification factor at level-$x$.
* $B$ = Horizontal dimension of building measured normal to wind direction, in m.
* $C_d$ = Deflection amplification factor.
* $C_f$ = Force coefficient to be used in determination of wind loads for other structures
* $C_N$ = Net pressure coefficient to be used in determination of wind loads for open buildings
* $C_p$ = External pressure coefficient to be used in determination of wind loads for buildings
* $C_s$ = Normalized acceleration response spectrum.
* $C_t$ = Numerical coefficient to determine building period
* $D$ = Diameter of a circular structure or member in m (as used in Sec 2.4).
* $D$ = Dead loads, or related internal moments and forces, Dead load consists of: a) weight of the member itself, b) weight of all materials of construction incorporated into the building to be permanently supported by the member, including built-in partitions, c) weight of permanent equipment (as used in Sec 2.7).
| $D'$ | = | Depth of protruding elements such as ribs and spoilers in m. |
| ----------------- | - | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| $E$ | = | Total load effects of earthquake that include both horizontal and
vertical, or related internal moments and forces. The horizontal
seismic load effect shall include system overstrength factor, $\Omega_o$, if
applicable. For specific definition of the earthquake load effect, $E$,
see Sec 2.5. |
| $E_h$ | = | Horizontal seismic load effect when the effect of system overstrength
factor, $\Omega_o$, is not included. |
| $E_{mh}$ | = | Horizontal seismic load effect when the effect of system overstrength
factor, $\Omega_o$, is included. |
| $E_v$ | = | Vertical effect of seismic load. |
| $F$ | = | Design wind force for other structures, in N (as used in Sec 2.4). |
| $F$ | = | Loads due to weight and pressures of fluids with well-defined
densities and controllable maximum heights or related internal
moments and forces (as used in Sec 2.7). |
| $F_a$ | = | Loads due to flood or tidal surge or related internal moments and
forces. |
| $F_i, F_n, F_x$ | = | Design lateral force applied to level-$i$, -$n$, or -$x$ respectively. |
| $F_c$ | = | Lateral forces on an element or component or on equipment supports. |
| $G$ | = | Gust effect factor |
| $G_f$ | = | Gust effect factor for MWFRSs of flexible buildings and other
structures |
| $GC_p$ | = | Product of external pressure coefficient and gust effect factor to be
used in determination of wind loads for buildings |
| $GC_{pf}$ | = | Product of the equivalent external pressure coefficient and gust-
effect factor to be used in determination of wind loads for MWFRS
of low-rise buildings |
| $GC_{pi}$ | = | Product of internal pressure coefficient and gust effect factor to be
used in determination of wind loads for buildings |
| $GC_{pn}$ | = | Combined net pressure coefficient for a parapet |
| $H$ | = | Height of hill or escarpment in Figure 6.2.4 in m. |
| $H$ | = | Loads due to weight and pressure of soil, water in soil, or other
materials, or related internal moments and forces (as used in Sec 2.7) |
| $I$ | = | Importance factor |
| $I_z$ | = | Intensity of turbulence from Eq. 6.2.7 |
| $K_1, K_2, K_3$ | = | Multipliers in Figure 6.2.4 to obtain $K_{zt}$ |
| $K_d$ | = | Wind directionality factor in Table 6.2.12 |
| $K_h$ | = | Velocity pressure exposure coefficient evaluated at height $z=h$ |
| $K_z$ | = | Velocity pressure exposure coefficient evaluated at height $z$ |
| $K_{zt}$ | = | Topographic factor as defined in Sec 2.4.7 |
| $L$ | = | Horizontal dimension of a building measured parallel to the wind
direction, in m (as used in Sec 2.4) |
| $L$ | = | Live loads due to intended use and occupancy, including loads due to
movable objects and movable partitions and loads temporarily
supported by the structure during maintenance, or related internal
moments and forces, $L$ includes any permissible reduction. If
resistance to impact loads is taken into account in design, such
effects shall be included with the live load $L$. (as used in Sec 2.7). |
| $L_h$ | = | Distance upwind of crest of hill or escarpment in Figure 6.2.4 to
where the difference in ground elevation is half the height of hill or
escarpment, in m. |
| $L_r$ | = | Roof live loads, or related internal moments and forces. (as used in
Sec 2.7) |
| $L_r$ | = | Horizontal dimension of return corner for a solid freestanding wall or
solid sign from Figure 6.2.20, in m. (as used in Sec 2.4) |
| $L_{\bar z}$ | = | Integral length scale of turbulence, in m. |
| *Level-i* | = | Floor level of the structure referred to by the subscript $i$, e.g., $i=1$
designates the first level above the base. |
| *Level-n* | = | Uppermost level in the main portion of the structure. |
| $M_x$ | = | Overturning moment at level-$x$ |
| $N_1$ | = | Reduced frequency from Eq. 6.2.14 |
| $N_i$ | = | Standard Penetration Number of soil layer $i$ |
| $P_{net}$ | = | Net design wind pressure from Eq. 6.2.4, in N/m2 |
| $P_{net30}$ | = | Net design wind pressure for Exposure A at $h$ = 9.1 m and $I$ = 1.0
from Figure 6.2.3, in N/m2. |
| $P_p$ | = | Combined net pressure on a parapet from Eq. 6.2.22, in N/m2. |
| $P_s$ | = | Net design wind pressure from Eq. 6.2.3, in N/m2. |
| $P_{s30}$ | = | Simplified design wind pressure for Exposure A at $h$ = 9.1 m and $I$ =
1.0 from Figure 6.2.2, in N/m2. |
| $P_x$ | = | Total vertical design load at level-$x$ |
| $P_w$ | = | Wind pressure acting on windward face in Figure 6.2.9, in N/m2. |
| $Q$ | = | Background response factor from Eq. 6.2.8 |
| $R$ | = | Resonant response factor from Eq. 6.2.12 |
| $R$ | = | Response reduction factor for structural systems. (as used in Sec 2.5) |
| $R$ | = | Rain load, or related internal moments and forces. (as used in Sec
2.7) |
| $R_B, R_h, R_L$ | = | Values from Eq. 6.2.15 |
| $R_i$ | = | Reduction factor from Eq. 6.2.18 |
| $R_n$ | = | Value from Eq. 6.2.13 |
| $S$ | = | Soil factor. |
| $S_a$ | = | Design Spectral Acceleration (in units of g) |
| $S_{ui}$ | = | Undrained shear strength of cohesive layer $i$ |
| $T$ | = | Fundamental period of vibration of structure, in seconds, of the
structure in the direction under consideration. (as used in Sec 2.5) |
| $T$ | = | Self-straining forces and cumulative effect of temperature, creep,
shrinkage, differential settlement, and shrinkage-compensating
concrete, or combinations thereof, or related internal moments and
forces. (as used in Sec 2.7) |
| $T_e$ | = | Effective fundamental period of the structure in the direction under
consideration, as determined for nonlinear static analysis |
| $V$ | = | Basic wind speed obtained from Figure 6.2.1 or Table 6.2.8, in m/s.
The basic wind speed corresponds to a 3-s gust speed at 10 m above
ground in Exposure Category B having an annual probability of
occurrence of 0.02. |
| $V$ | = | Total design base shear calculated by equivalent static analysis. (as
used in Sec 2.5) |
| $V_i$ | = | Unpartitioned internal volume m3 |
| $\bar V_{\bar z}$ | = | mean hourly wind speed at height $\bar z$, m/s. |
| $V_1$ | = | Total applied lateral force at the first increment of lateral load in
nonlinear static analysis. |
| $V_y$ | = | Effective yield strength determined from a bilinear curve fitted to the
capacity curve |
| $V_{rs}$ | = | Total design base shear calculated by response spectrum analysis |
| $V_{th}$ | = | Total design base shear calculated by time history analysis |
| $V_{si}$ | = | Shear wave velocity of soil layer $i$ |
| $V_x$ | = | Design storey shear in storey $x$ |
| $W$ | = | Width of building in Figures 6.2.12, 6.2.14(a) and 6.2.14(b), and
width of span in Figures 6.2.13 and 6.2.15 in m. |
| $W$ | = | Total seismic weight of building. (as used in Sec 2.5) |
| $W$ | = | Wind load, or related internal moments and forces. (as used in Sec
2.7) |
| $X$ | = | Distance to center of pressure from windward edge in Figure 6.2.18,
in m. |
| $Z$ | = | Seismic zone coefficient. |
| $a$ | = | Width of pressure coefficient zone, in m. |
| $b$ | = | Mean hourly wind speed factor in Eq. 6.2.16 from Table 6.2.10 |
| $\hat b$ | = | 3-s gust speed factor from Table 6.2.10 |
| $c$ | = | Turbulence intensity factor in Eq. 6.2.7 from Table 6.2.10 |
| $e_{ai}$ | = | Accidental eccentricity of floor mass at level-$i$ |
| $g$ | = | Acceleration due to gravity. |
| $g_Q$ | = | Peak factor for background response in Equations 6.2.6 and 6.2.10 |
| $g_R$ | = | Peak factor for resonant response in Eq. 6.2.10 |
| $g_V$ | = | Peak factor for wind response in Equations 6.2.6 and 6.2.10 |
| $h$ | = | Mean roof height of a building or height of other structure, except
that eave height shall be used for roof angle $\theta$ of less than or equal to
10°, in m. |
| $h_e$ | = | Roof eave height at a particular wall, or the average height if the
eave varies along the wall |
| $h_i, h_n, h_x$ | = | Height in metres above the base to level $i$, -$n$ or -$x$ respectively |
| $h_{sx}$ | = | Storey Height of storey $x$ (below level-$x$) |
| $l$ | = | Integral length scale factor from Table 6.2.10 in m. |
| $n_1$ | = | Building natural frequency, Hz |
| $p$ | = | Design pressure to be used in determination of wind loads for
buildings, in N/m2 |
| $p_L$ | = | Wind pressure acting on leeward face in Figure 6.2.9, in N/m2 |
| $q$ | = | Velocity pressure, in N/m2. |
| $q_h$ | = | Velocity pressure evaluated at height $z=h$, in N/m2 |
| $q_i$ | = | Velocity pressure for internal pressure determination, in N/m2. |
| $q_p$ | = | Velocity pressure at top of parapet, in N/m2. |
| $q_z$ | = | Velocity pressure evaluated at height z above ground, in N/m2. |
| $r$ | = | Rise-to-span ratio for arched roofs. |
| $s$ | = | Vertical dimension of the solid freestanding wall or solid sign from
Figure 6.2.20, in m. |
| $w_i, w_x$ | = | Portion of $W$ which is assigned to level $i$ and $x$ respectively |
| $x$ | = | Distance upwind or downwind of crest in Figure 6.2.4, in m. |
| $z$ | = | Height above ground level, in m. |
| $\bar z$ | = | Equivalent height of structure, in m. |
| $z_g$ | = | Nominal height of the atmospheric boundary layer used in this
standard. Values appear in Table 6.2.10 |
| $z_{min}$ | = | Exposure constant from Table 6.2.10 |
| $\Delta_a$ | = | Maximum allowable storey drift |
| $\Delta_x$ | = | Design storey drift of storey $x$ |
| $\in$ | = | Ratio of solid area to gross area for solid freestanding wall, solid
sign, open sign, face of a trussed tower, or lattice structure |
| $\bar\in$ | = | Integral length scale power law exponent in Eq. 6.2.9 from Table
6.2.10 |
| $\Omega_o$ | = | Horizontal seismic overstrength factor from Table 6.2.19 |
| $\alpha$ | = | 3-s gust-speed power law exponent from Table 6.2.10 |
| $\hat\alpha$ | = | Reciprocal of $a$ from Table 6.2.10 |
| $\bar\alpha$ | = | Mean hourly wind-speed power law exponent in Eq. 6.2.16 from
Table 6.2.10 |
| $\beta$ | = | Damping ratio, percent critical for buildings or other structures |
| $\delta_i$ | = | Horizontal displacement at level-i relative to the base due to applied
lateral forces. |
| $\delta_j$ | = | The displacement of the control point at load increment $j$. |
| $\delta_T$ | = | The target displacement of the control point. |
| $\delta_1$ | = | The displacement of the control point at the first increment of lateral
load. |
| $\delta_y$ | = | The effective yield displacement of the control point determined
from a bilinear curve fitted to the capacity curve |
| $\eta$ | = | Value used in Eq. 6.2.15 (see Sec 2.4.8.2) |
| $\eta$ | = | Damping correction factor |
| $\theta$ | = | Angle of plane of roof from horizontal, in degrees. (as used in Sec
2.4) |
| $\theta$ | = | Stability coefficient to assess P-delta effects. (as used in Sec 2.5) |
| $\lambda$ | = | Adjustment factor for building height and exposure from Figures
6.2.2 and 6.2.3 |
| $\nu$ | = | Height-to-width ratio for solid sign |
| $\xi$ | = | Viscous damping ratio of the structure |
| $\phi_{ik}$ | = | Modal shape coefficient at level $i$ for mode $k$ |
## **2.2 Dead Loads**
### **2.2.1 General**
The minimum design dead load for buildings and portions thereof shall be determined in accordance with the provisions of this Section. In addition, design of the overall structure and its primary load-resisting systems shall conform to the general design provisions given in Chapter 1.
### **2.2.2 Definition**
Dead Load is the vertical load due to the weight of permanent structural and nonstructural components and attachments of a building such as walls, floors, ceilings, permanent partitions and fixed service equipment etc.
### **2.2.3 Assessment of Dead Load**
Dead load for a structural member shall be assessed based on the forces due to:
* weight of the member itself,
* weight of all materials of construction incorporated into the building to be supported permanently by the member,
* weight of permanent partitions,
* weight of fixed service equipment, and
* net effect of prestressing.
### **2.2.4 Weight of Materials and Constructions**
In estimating dead loads, the actual weights of materials and constructions shall be used, provided that in the absence of definite information, the weights given in Tables 6.2.1 and 6.2.2 shall be assumed for the purposes of design.
**Table 6.2.1: Unit Weight of Basic Materials**
| **Material** | **Unit Weight**
**(kN/m****3****)** | **Material** | **Unit Weight**
**(kN/m****3****)** |
| --------------------------------------------- | --------------------------------------------------- | --------------- | --------------------------------------------------- |
| Aluminium | 27.0 | Granite, Basalt | 26.4 |
| Asphalt | 21.2 | Iron - cast | 70.7 |
| Brass | 83.6 | - wrought | 75.4 |
| Bronze | 87.7 | Lead | 111.0 |
| Brick | 18.9 | Limestone | 24.5 |
| Cement | 14.7 | Marble | 26.4 |
| Coal, loose | 8.8 | Sand, dry | 15.7 |
| Concrete -stone aggregate
(unreinforced) | 22.8\* | Sandstone | 22.6 |
| -brick aggregate
(unreinforced) |
20.4\* | Slate | 28.3 |
| Copper | 86.4 | Steel | 77.0 |
| Cork, normal | 1.7 | Stainless Steel | 78.75 |
| Cork, compressed | 3.7 | Timber | 5.9-11.0 |
| Glass, window (soda-lime) | 25.5 | Zinc | 70.0 |
* for reinforced concrete, add 0.63 kN/m3 for each 1% by volume of main reinforcement
**Table 6.2.2: Weight of Construction Materials.**
| **Material/Component/Member**
| **Weight per** | **Material/Component/Member** | **Weight per** |
| ------------------------------------------- | ---------------------------------------------------------------------- | -------------------------------------------------- | --------------------------------------------------------------------- |
| | **Unit Area**
**(kN/m****2****)** | | **Unit Area**
**(kN/m****2****)** |
| **Floor** | | **Walls and Partitions** | |
| Asphalt, 25 mm thick | 0.526 | Acrylic resin sheet, flat, per | 0.012 |
| Clay tiling, 13 mm thick | 0.268 | mm thickness | |
| Concrete slab (stone aggregate)\*: | | Asbestos cement sheeting: | |
| solid, 100 mm thick | 2.360 | 4.5 mm thick | 0.072 |
| solid, 150 mm thick | 3.540 | 6.0 mm thick | 0.106 |
| Galvanized steel floor deck (excl. | 0.147- | Brick masonry work, excl. | |
| topping) | 0.383 | plaster: | |
| Magnesium oxychloride: | | burnt clay, per 100 mm | 1.910 |
| normal (sawdust filler), 25 mm | 0.345 | thickness | |
| thick | | sand-lime, per 100 mm | 1.980 |
| heavy
duty
(mineral
filler), | 0.527 | thickness | |
| 25 mm thick | | Concrete (stone aggregate)\*: | |
| Terrazzo paving 16 mm thick | 0.431 | 100 mm thick | 2.360 |
| **Material/Component/Member**
| **Weight per**
**Unit Area**
**(kN/m****2****)** | **Material/Component/Member** | **Weight per**
**Unit Area**
**(kN/m****2****)** |
| **Roof** | | 150 mm thick | 3.540 |
| Acrylic resin sheet, corrugated: | | 250 mm thick | 5.900 |
| 3 mm thick, standard corrugations | 0.043 | Fibre insulation board, per
| 0.034 |
| 3 mm thick, deep corrugations | 0.062 | 10 mm thickness | |
| Aluminium, corrugated sheeting: | | Fibrous plaster board, per
| 0.092 |
| (incl. lap and fastenings) | | 10 mm thickness
| |
| 1.2 mm thick | 0.048 | Glass, per 10 mm thickness
| 0.269
|
| 0.8 mm thick | 0.028 | Hardboard, per 10 mm
thickness | 0.961 |
| 0.6 mm thick | 0.024 | | |
| Aluminium sheet(plain):
| | Particle or flake board, per
10 mm thickness | 0.075 |
| 1.2 mm thick | 0.033 | Plaster board, per 10 mm | 0.092 |
| 1.0 mm thick
| 0.024
|
thickness | |
| 0.8 mm thick | 0.019 | Plywood, per 10 mm | 0.061 |
| Bituminous felt (5 ply) and gravel | 0.431 | thickness | |
| Slates: | | **Ceiling** | |
| 4.7 mm thick | 0.335 | Fibrous plaster, 10 mm thick | 0.081 |
| 9.5 mm thick | 0.671 | Cement plaster, 13 mm thick | 0.287 |
| Steel sheet, flat galvanized: | | Suspended metal lath and
| 0.480 |
| 1.00 mm thick | 0.082 | plaster | |
| 0.80 mm thick | 0.067 | (two faced incl. studding) | |
| 0.60 mm thick | 0.053 | **Miscellaneous** | |
| Steel, galvanized std. corrugated | | Felt (insulating), per 10 mm
| 0.019 |
| sheeting: | | thickness | |
| (incl. lap and fastenings) | | Plaster: | |
| 1.0 mm thick | 0.120 | Cement plaster, per 10
| 0.230 |
| 0.8 mm thick | 0.096 | mm thickness | |
| 0.6 mm thick | 0.077 | Lime plaster, per 10 mm
| 0.191 |
| Tiles : | | thickness
| |
| terra-cotta tiles (French pattern)
| 0.575
| PVC sheet, per 10 mm
thickness | 0.153 |
| concrete , 25 mm thick | 0.527 | Rubber avin er 10 mm | |
| clay tiles | 0.6-0.9 | pg, p
thickness | 0.151 |
| | | Terra-cotta Hollow Block
Masonry: | |
| | | 75 mm thick | 0.671 |
| | | 100 mm thick | 0.995 |
| | | 150 mm thick | 1.388 |
* For brick aggregate, 90% of the listed values may be used.
### **2.2.5 Weight of Permanent Partitions**
When partition walls are indicated on the plans, their weight shall be considered as dead load acting as concentrated line loads in their actual positions on the floor. The loads due to anticipated partition walls, which are not indicated on the plans, shall be treated as live loads and determined in accordance with Sec 2.3.6.
### **2.2.6 Weight of Fixed Service Equipment**
Weights of fixed service equipment and other permanent machinery, such as electrical feeders and other machinery, heating, ventilating and air-conditioning systems, lifts and escalators, plumbing stacks and risers etc. shall be included as dead load whenever such equipment are supported by structural members.
### **2.2.7 Additional Loads**
In evaluating the final dead loads on a structural member for design purposes, allowances shall be made for additional loads resulting from the (i) difference between the prescribed and the actual weights of the members and construction materials; (ii) inclusion of future installations; (iii) changes in occupancy or use of buildings; and (iv) inclusion of structural and non-structural members not covered in Sections 2.2.2 and 2.2.3.
## **2.3 Live Loads**
### **2.3.1 General**
The live loads used for the structural design of floors, roof and the supporting members shall be the greatest applied loads arising from the intended use or occupancy of the building, or from the stacking of materials and the use of equipment and propping during construction, but shall not be less than the minimum design live loads set out by the provisions of this Section. For the design of structural members for forces including live loads, requirements of the relevant Sections of Chapter 1 shall also be fulfilled.
### **2.3.2 Definition**
Live load is the load superimposed by the use or occupancy of the building not including the environmental loads such as wind load, rain load, earthquake load or dead load.
### **2.3.3 Minimum Floor Live Loads**
The minimum floor live loads shall be the greatest actual imposed loads resulting from the intended use or occupancy of the floor, and shall not be less than the uniformly distributed load patterns specified in Sec 2.3.4 or the concentrated loads specified in Sec 2.3.5 whichever produces the most critical effect. The live loads shall be assumed to act vertically upon the area projected on a horizontal plane.
### **2.3.4 Uniformly Distributed Loads**
The uniformly distributed live load shall not be less than the values listed in Table 6.2.3, reduced as may be specified in Sec 2.3.13, applied uniformly over the entire area of the floor, or any portion thereof to produce the most adverse effects in the member concerned.
### **2.3.5 Concentrated Loads**
The concentrated load to be applied non-concurrently with the uniformly distributed load given in Sec 2.3.4, shall not be less than that listed in Table 6.2.3. Unless otherwise specified in Table 6.2.3 or in the following paragraph, the concentrated load shall be applied over an area of 300 mm × 300 mm and shall be located so as to produce the maximum stress conditions in the structural members.
In areas where vehicles are used or stored, such as car parking garages, ramps, repair shops etc., provision shall be made for concentrated loads consisting of two or more loads spaced nominally 1.5 m on centres in absence of the uniform live loads. Each load shall be 40 percent of the gross weight of the maximum size vehicle to be accommodated and applied over an area of 750 mm × 750 mm. For the storage of private or pleasure-type vehicles without repair or fuelling, floors shall be investigated in the absence of the uniform live load, for a minimum concentrated wheel load of 9 kN spaced 1.5 m on centres, applied over an area of 750 mm × 750 mm. The uniform live loads for these cases are provided in Table 6.2.3. The condition of concentrated or uniform live load producing the greater stresses shall govern.
**Table 6.2.3: Minimum Uniformly Distributed and Concentrated Live Loads*****a***
| **Occupancy or Use** | **Uniform** | **Concentrated** |
| ----------------------------------------------------------------------------------------------- | ----------------------------------------- | ------------------------------------------------ |
| | **kN/m****2** | **kN** |
| Apartments (see Residential) | | |
| Access floor systems | | |
| Office use | 2.40 | 9.0 |
| Computer use | 4.80 | 9.0 |
| Armories and drill rooms | 7.20 | -- |
| **Occupancy or Use** | **Uniform**
**kN/m****2** | **Concentrated**
**kN** |
| Assembly areas and theaters | | |
| Fixed seats (fastened to floor) | 2.90 | -- |
| Lobbies | 4.80 | -- |
| Movable seats | 4.80 | -- |
| Platforms (assembly) | 4.80 | -- |
| Stage floors | 7.20 | -- |
| Balconies (exterior) | 4.80 | -- |
| On one- and two-family residences only, and not
exceeding 19.3m2 | 2.90 | -- |
| Bowling alleys, poolrooms, and similar recreational areas | 3.60 | -- |
| Catwalks for maintenance access | 2.00 | 1.33 |
| Corridors | | |
| First floor | 4.80 | -- |
| Other floors, same as occupancy served except as indicated | | |
| Dance halls and ballrooms | 4.80 | -- |
| Decks (patio and roof) | Same as a
for the typ
acco | rea served, or
e of occupancy
mmodated |
| Dining rooms and restaurants | 4.80 | -- |
| Dwellings (see\_Residential\_) | -- | |
| Elevator machine roomgrating (on area of 2,580mm2 ) | -- | 1.33 |
| Finish light floor plateconstruction(on area of 645mm2) | -- | 0.90 |
| Fire escapes | 4.80 | -- |
| On single-family dwellings only | 2.00 | -- |
| Fixed ladders | See S | ec 2.3.11 |
| Garages (passenger vehicles only), Trucks and buses | 2 | .0*b,c* |
| Grandstands | See\_Stadiu\_
*Bl* | \_ms and arenas
*eachers* |
| Gymnasiums—main floors and balconies | 4.80 | -- |
| Handrails, guardrails, and grab bars | See S | ec 2.3.11 |
| Hospitals | | |
| Operating rooms, laboratories | 2.90 | 4.50 |
| Patient rooms | 2.00 | 4.50 |
| Corridors above first floor | 3.80 | 4.50 |
| | **kN/m****2** | **kN** |
| Hotels | See\_R\_ | *esidential* |
| Libraries | | |
| Reading rooms | 2.90 | 4.50 |
| Stack rooms | 7.20*d* | 4.50 |
| Corridors above first floor | 3.80 | 4.50 |
| Manufacturing\* | | |
| Light | 4.00 | 6.00 |
| Medium | 6.00 | 9.00 |
| Heavy | 12.00 | 13.40 |
| Garments manufacturing floor except stacking or storage
area | 4.00e | -- |
| Stacking or storage area of garments manufacturing
industry | 6.00*f* | 10.00*f* |
| Marquees | 3.60 | -- |
| OfficeBuildings | | |
| File and computer rooms shall be designed for
heavier loads based on anticipated occupancy | | |
| Lobbies andfirst-floorcorridors | 4.80 | 9.00 |
| Offices | 2.40 | 9.00 |
| Corridors above first floor | 3.80 | 9.00 |
| Penal Institutions | | |
| Cell blocks | 2.00 | -- |
| Corridors | 4.80 | -- |
| Residential | | |
| Dwellings (one- and two-family) | | |
| Uninhabitable attics without storage | 0.50 | -- |
| Uninhabitable attics with storage | 1.00 | -- |
| Habitable attics and sleeping areas | 1.50 | -- |
| All other areas except stairs and balconies | 2.00 | -- |
| Hotels and multifamily houses | | |
| Private rooms and corridors serving them | 2.00 | -- |
| Public rooms and corridors serving them | 4.80 | -- |
| Reviewing stands, grandstands, and bleachers | 4.80*g* | -- |
| **Occupancy or Use** | **Uniform**
**kN/m****2** | **Concentrated**
**kN** |
| Roofs | | |
| Ordinary flat roof | 1.00*h* | -- |
| Pitched and curved roofs | See T | able 6.2.4 |
| Roofs used for promenade purposes | 2.90 | -- |
| Roofs used for roof gardens or assembly purposes | 4.80 | -- |
| Roofs used for other special purposes | See N | ote*i* below |
| Awnings and canopies | | |
| Fabric construction supported by a lightweight rigid
skeleton structure | 0.24
(nonredu-
ceable) | -- |
| All other construction | 1.00 | -- |
| Primary roof members exposed to a work floor | | |
| Single panel point of lower chord of roof trusses or | -- | 9.00 |
| any
point along primary
structural members | | |
| supporting
roofs
over
manufacturing,
storage | | |
| warehouses, and repairgarages | | |
| All other occupancies | -- | 1.33 |
| All roof surfaces subject to maintenance workers | -- | 1.33 |
| Schools | | |
| Classrooms | 2.00 | 4.50 |
| Corridors above first floor | 3.80 | 4.50 |
| First-floor corridors | 4.80 | 4.50 |
| Scuttles, skylight ribs, and accessible ceilings | | 0.90 |
| Sidewalks, vehicular driveways, and yards subject to
trucking | 12.00*j* | 35.60*k* |
| Stadiums and arenas | | |
| Bleachers | 4.80
*g* | -- |
| Fixed seats (fastened to floor) | 2.90
*g* | -- |
| Stairs and exit ways | 4.80 | See Note*l* |
| One- and two-family residences only | 2.00 | below
-- |
| **Occupancy or Use** | **Uniform**
**kN/m****2** | **Concentrated**
**kN** |
| ---------------------------------------------------------------------------------------- | ----------------------------------------- | ---------------------------- |
| Storage areas above ceilings | 1.00 | -- |
| Storage warehouses (shall be designed for
heavier loads if required for anticipated | | |
| storage) | | |
| Light | 6.00 | -- |
| Heavy | 12.00 | -- |
| Stores | | |
| Retail | | |
| First floor | 4.80 | 4.50 |
| Upper floors | 3.60 | 4.50 |
| Wholesale, all floors | 6.00 | 4.50 |
| Vehicle barriers | See S | ec 2.3.11 |
| Walkways and elevated platforms (other than exit ways) | 2.90 | -- |
| Yards and terraces, pedestrian | 4.80 | -- |
| Notes: | | |
* *a* It must be ensured that the average weight of equipment, machinery, raw materials and products that may occupy the floor is less than the specified value in the Table. In case the weight exceeds the specified values in the Table, actual maximum probable weight acting in the actual manner shall be used in the analysis and design.
* *b* Floors in garages or portions of a building used for the storage of motor vehicles shall be designed for the uniformly distributed live loads of Table 6.2.3 or the following concentrated load: (1) for garages restricted to passenger vehicles accommodating not more than nine passengers, 13.35 kN acting on an area of 114 mm by 114 mm footprint of a jack; and (2) for mechanical parking structures without slab or deck that are used for storing passenger car only, 10 kN per wheel.
* *c* Garages accommodating trucks and buses shall be designed in accordance with an approved method, which contains provisions for truck and bus loadings.
* *d* The loading applies to stack room floors that support non-mobile, double-faced library book stacks subject to the following limitations: (1) The nominal book stack unit height shall not exceed 2290 mm; (2) the nominal shelf depth shall not exceed 300 mm for each face; (3) parallel rows of double-faced book stacks shall be separated by aisles not less than 900 mm wide.
* *e* Subject to the provisions of reduction of live load as per Sec 2.3.13
* *f* Uniformly distributed and concentrated load provisions are applicable for a maximum floor height of 3.5 m. In case of higher floor height, the load(s) must be proportionally increased.
* *g* In addition to the vertical live loads, the design shall include horizontal swaying forces applied to each row of the seats as follows: 0.350 kN per linear meter of seat applied in a direction parallel to each row of seats and 0.15 kN per linear meter of seat applied in a direction perpendicular to each row of seats. The parallel and perpendicular horizontal swaying forces need not be applied simultaneously.
* *h* Where uniform roof live loads are reduced to less than 1.0 kN/m2 in accordance with Sec 2.3.14.1 and are applied to the design of structural members arranged so as to create continuity, the reduced roof live load shall be applied to adjacent spans or to alternate spans, whichever produces the greatest unfavorable effect.
* *i* Roofs used for other special purposes shall be designed for appropriate loads as approved by the authority having jurisdiction.
* *j* Other uniform loads in accordance with an approved method, which contains provisions for truck loadings, shall also be considered where appropriate.
* *k* The concentrated wheel load shall be applied on an area of 114 mm by 114 mm footprint of a jack.
* *l* Minimum concentrated load on stair treads (on area of 2,580 mm2 ) is 1.33 kN.
* The loading in industrial buildings varies considerably and so the loadings under the terms ‘light,’ ‘medium’ and ‘heavy’ are introduced in order to allow for which the relevant floor is designed. It is however important to assess the actual loads to ensure that they are not in excess of the stipulated load, in case where they are in excess, the design shall be based on the actual loadings.
### **2.3.6 Provision for Partition Walls**
When partitions, not indicated on the plans, are anticipated to be placed on the floors, their weight shall be included as an additional live load acting as concentrated line loads in an arrangement producing the most severe effect on the floor, unless it can be shown that a more favourable arrangement of the partitions shall prevail during the future use of the floor.
In the case of light partitions, wherein the total weight per metre run is not greater than 5.5 kN, a uniformly distributed live load may be applied on the floor in lieu of the concentrated line loads specified above. Such uniform live load per square metre shall be at least 33% of the weight per metre run of the partitions, subject to a minimum of 1.2 kN/m2 .
### **2.3.7 More than One Occupancy**
Where an area of a floor is intended for two or more occupancies at different times, the value to be used from Table 6.2.3 shall be the greatest value for any of the occupancies concerned.
### **2.3.8 Minimum Roof Live Loads**
Roof live loads shall be assumed to act vertically over the area projected by the roof or any portion of it upon a horizontal plane, and shall be determined as specified in Table 6.2.4.
**Table 6.2.4: Minimum Roof Live Loads(****1** **)**
| **Typ** | **e and Slope of Roof** | **Distributed**
**Load, kN/m****2**
**Concentrated**
**Load, kN** |
| ------- | -------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------- |
| I | Flat roof (slope = 0) | See Table 6.2.3 |
| II | (A) Pitched or sloped roof (0 \< slope \< 1/3) | 1.0
0.9 |
| | (B) Arched roof or dome (rise \< 1/8 span) | |
| III | (A) Pitched or sloped roof (1/3 ≤ slope \< 1.0) | 0.8
0.9 |
| | (B) Arched roof or dome (1/8 ≤ rise \< 3/8 span) | |
| IV | (A) Pitched or sloped roof (slope ≥ 1.0)
(B) Arched roof or dome (rise ≥ 3/8 span) | 0.6
0.9 |
| V | Greenhouse, and agriculture buildings | 0.5
0.9 |
| VI | Canopies and awnings, except those with cloth
covers | Same as given in I to IV
above based on the type
and slope. |
* Note: **(1)** Greater of this load and rain load as specified in Sec 2.6.2 shall be taken as the design live load for roof. The distributed load shall be applied over the area of the roof projected upon a horizontal plane and shall not be applied simultaneously with the concentrated load. The concentrated load shall be assumed to act upon a 300 mm × 300 mm area and need not be considered for roofs capable of laterally distributing the load, e.g. reinforced concrete slabs.
### **2.3.9 Loads not Specified**
Live loads, not specified for uses or occupancies in Sections 2.3.3, 2.3.4 and 2.3.5, shall be determined from loads resulting from:
* (a) weight of the probable assembly of persons;
* (b) weight of the probable accumulation of equipment and furniture, and
* (c) weight of the probable storage of materials.
### **2.3.10 Partial Loading and Other Loading Arrangements**
The full intensity of the appropriately reduced live load applied only to a portion of the length or area of a structure or member shall be considered, if it produces a more unfavourable effect than the same intensity applied over the full length or area of the structure or member.
Where uniformly distributed live loads are used in the design of continuous members and their supports, consideration shall be given to full dead load on all spans in combination with full live loads on adjacent spans and on alternate spans whichever produces a more unfavourable effect.
### **2.3.11 Other Live Loads**
Live loads on miscellaneous structures and components, such as handrails and supporting members, parapets and balustrades, ceilings, skylights and supports, and the like, shall be determined from the analysis of the actual loads on them, but shall not be less than those given in Table 6.2.5.
### **2.3.12 Impact and Dynamic Loads**
The live loads specified in Sec 2.3.3 shall be assumed to include allowances for impacts arising from normal uses only. However, forces imposed by unusual vibrations and impacts resulting from the operation of installed machinery and equipment shall be determined separately and treated as additional live loads. Live loads due to vibration or impact shall be determined by dynamic analysis of the supporting member or structure including foundations, or from the recommended values supplied by the manufacture of the particular equipment or machinery. In absence of definite information, values listed in Table 6.2.6 for some common equipment, shall be used for design purposes.
**Table 6.2.5: Miscellaneous Live Loads**
| **Structural Member or Component** | **Live Load****(1)**
**(kN/m)** |
| -------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------- |
| **A. Handrails, parapets and supports:** | |
| (a) Light access stairs, gangways etc. | |
| (i) width ≤ 0.6 m | 0.25 |
| (ii) width > 0.6 m | 0.35 |
| (b) Staircases other than in (a) above, ramps, balconies: | |
| (i) Single dwelling and private | 0.35 |
| (ii) Staircases in residential buildings | 0.35 |
| (iii) Balconies or portion thereof, stands etc. having fixed seats
within 0.55 m of the barrier | 1.5 |
| (iv) Public assembly buildings including theatres, cinemas,
assembly halls, stadiums, mosques, churches, schools etc. | 3.0 |
| (v) Buildings and occupancies other than (i) to (iv) above | 0.75 |
| **B. Vehicle barriers for car parks and ramps:** | |
| (a) For vehicles having gross mass ≤ 2500 kg | 100(2) |
| --------------------------------------------- | ---------------------- |
| (b) For vehicles having gross mass > 2500 kg | 165(2) |
| (c) For ramps of car parks etc. | see note(3) |
* Notes: (1) These loads shall be applied non-concurrently along horizontal and vertical directions, except as specified in note (2) below.
* (2) These loads shall be applied only in the horizontal direction, uniformly distributed over any length of 1.5 m of a barrier and shall be considered to act at bumper height. For case 2(a) bumper height may be taken as 375 mm above floor level.
* (3) Barriers to access ramps of car parks shall be designed for horizontal forces equal to 50% of those given in 2(a) and 2(b) applied at a level of 610 mm above the ramp. Barriers to straight exit ramps exceeding 20 m in length shall be designed for horizontal forces equal to twice the values given in 2(a) and 2(b).
**Table 6.2.6: Minimum Live Loads on Supports and Connections of Equipment due to Impact****(1)**
*Additional load due to impact as percentage of static load including self-weight*
| **Equipment or Machinery** | **Vertical** | **Horizontal** |
| ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 1. Lifts, hoists and related
operating machinery | 100% | Not applicable |
| 2. Light machinery (shaft or
motor driven) | 20% | Not applicable |
| 3. Reciprocating machinery, or
power driven units. | 50% | Not applicable |
| 4. Hangers supporting floors and
balconies | 33% | Not applicable |
| 5. Cranes : | | |
| (a) Electric overhead
cranes | 25% of
maximum
wheel load | (i) Transverse to the rail :
20% of the weight of trolley
and lifted load only, applied
one-half at the top of each rail
(ii) Along the rail :
10% of maximum wheel load
applied at the top of each rail |
| (b) Manually operated
cranes | 50% of the
values in (a)
above | 50% of the values in (a) above |
| (c) Cab-operated travelling
cranes | 25% | Not applicable |
| (1) All these loads shall be increased if so recommended by the manufacturer. For machinery and equipment not listed, impact loads shall be those recommended by the manufacturers, or determined by dynamic analysis. | | |
### **2.3.13 Reduction of Live Loads**
Except for roof uniform live loads, all other minimum uniformly distributed live loads, *Lo* in Table 6.2.3, may be reduced according to the following provisions.
#### 2.3.13.1 General
Subject to the limitations of Sections 2.3.13.2 to 2.3.13.5, members for which a value of $K_{LL}A_T$ is 37.16 m2 or more are permitted to be designed for a reduced live load in accordance with the following formula:
$$
L = L_o\left(0.25 + \frac{4.57}{\sqrt{K_{LL}A_T}}\right) \tag{6.2.1}
$$
Where, *L* = reduced design live load per m2 of area supported by the member; *L0* = unreduced design live load per m2 of area supported by the member (Table 6.2.3); *KLL* = live load element factor (Table 6.2.7); *AT* = tributary area in m2 , *L* shall not be less than 0.50 *L0* for members supporting one floor and *L* shall not be less than 0.40 *L0* for members supporting two or more floors.
**Table 6.2.7: Live Load Element Factor,** $K_{LL}$
| **Element** | $K_{LL}$\* |
| ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------- |
| Interior columns | 4 |
| Exterior columns without cantilever slabs | 4 |
| Edge columns with cantilever slabs | 3 |
| Corner columns with cantilever slabs | 2 |
| Edge beams without cantilever slabs | 2 |
| Interior beams | 2 |
| All other members not identified including: Edge beams with cantilever slabs, Cantilever beams, One-way slabs, Two-way slabs, Members without provisions for continuous shear transfer normal to their span | 1 |
* \*In lieu of the preceding values, $K_{LL}$ is permitted to be calculated.
#### 2.3.13.2 Heavy live loads
Live loads that exceed 4.80 kN/m2 shall not be reduced.
Exception: Live loads for members supporting two or more floors may be reduced by 20 percent.
#### 2.3.13.3 Passenger car garages
The live loads shall not be reduced in passenger car garages.
Exception: Live loads for members supporting two or more floors may be reduced by 20 percent.
#### 2.3.13.4 Special occupancies
* (a) Live loads of 4.80 kN/m2 or less shall not be reduced in public assembly occupancies.
* (b) There shall be no reduction of live loads for cyclone shelters.
#### 2.3.13.5 Limitations on one-way slabs
The tributary area, *AT* , for one-way slabs shall not exceed an area defined by the slab span times a width normal to the span of 1.5 times the slab span.
### **2.3.14 Reduction in Roof Live Loads**
The minimum uniformly distributed roof live loads, *Lo* in Table 6.2.3, are permitted to be reduced according to the following provisions.
#### 2.3.14.1 Flat, pitched, and curved roofs.
Ordinary flat, pitched, and curved roofs are permitted to be designed for a reduced roof live load, as specified in Eq. 6.2.2 or other controlling combinations of loads, as discussed later in this Chapter, whichever produces the greater load. In structures
such as greenhouses, where special scaffolding is used as a work surface for workmen and materials during maintenance and repair operations, a lower roof load than specified in Eq. 6.2.2 shall not be used unless approved by the authority having jurisdiction. On such structures, the minimum roof live load shall be 0.60 kN/m2 .
$$
L_r = L_oR_1R_2 \text{ } (0.60 \leq L_r \leq 1.00) \tag{6.2.2}
$$
Where,
* $L_r =$ reduced roof live load per m2 of horizontal projection in kN/m2
The reduction factors $R_1$ and $R_2$ shall be determined as follows:
$R_1 = 1$ for $A_t \leq 18.58$ m2
$= 1.2 - 0.011A_t$ for $18.58$ m2 $< A_t < 55.74$ m2
$= 0.6$ for $A_t \geq 55.74$ m2
* $A_t =$ tributary area in m2 supported by any structural member and
$R_2 = 1$ for $F \leq 4$
$= 1.2 - 0.05F$ for $4 < F < 12$
$= 0.6$ for $F \geq 12$
For a pitched roof, $F = 0.12 \times$ slope, with slope expressed in percentage points and, for an arch or dome, $F =$ rise-to-span ratio multiplied by 32.
#### 2.3.14.2 Special purpose roofs.
Roofs that have an occupancy function, such as roof gardens, assembly purposes, or other special purposes are permitted to have their uniformly distributed live load reduced in accordance with the requirements of Sec 2.3.13.
## **2.4 Wind Loads**
### **2.4.1 General**
Scope: Buildings and other structures, including the Main Wind-Force Resisting System (MWFRS) and all components and cladding thereof, shall be designed and constructed to resist wind loads as specified herein.
Allowed Procedures: The design wind loads for buildings and other structures, including the MWFRS and component and cladding elements thereof, shall be determined using one of the following procedures:
* Method 1: Simplified Procedure as specified in Sec 2.4.2 for buildings and structures meeting the requirements specified therein;
* Method 2: Analytical Procedure as specified in Sec 2.4.3 for buildings and structures meeting the requirements specified therein;
* Method 3: Wind Tunnel Procedure as specified in Sec 2.4.16.
Wind Pressures Acting on opposite faces of each building surface. In the calculation of design wind loads for the MWFRS and for components and cladding for buildings, the algebraic sum of the pressures acting on opposite faces of each building surface shall be taken into account.
**Minimum Design Wind Loading**
The design wind load, determined by any one of the procedures specified in Sec 2.4.1, shall be not less than specified in this Section.
Main Wind-Force Resisting System: The wind load to be used in the design of the MWFRS for an enclosed or partially enclosed building or other structure shall not be less than 0.5 kN/m2 multiplied by the area of the building or structure projected onto a vertical plane normal to the assumed wind direction. The design wind force for open buildings and other structures shall be not less than 0.5 kN/m2 multiplied by the area .
Components and Cladding **:** The design wind pressure for components and cladding of buildings shall not be less than a net pressure of 0.5 kN/m2 acting in either direction normal to the surface.
### **2.4.2 Method 1: Simplified Procedure**
#### 2.4.2.1 Scope
A building whose design wind loads are determined in accordance with this Section shall meet all the conditions of Sec 2.4.2.2 or Sec 2.4.2.3. If a building qualifies only under Sec 2.4.2.3 for design of its components and cladding, then its MWFRS shall be designed by Method 2 or Method 3.
Limitations on Wind Speeds: Variation of basic wind speeds with direction shall not be permitted unless substantiated by any established analytical method or wind tunnel testing.
#### 2.4.2.2 Main wind-force resisting systems
For the design of MWFRSs the building must meet all of the following conditions:
* (1) The building is a simple diaphragm building as defined in Sec 2.1.3.
* (2) The building is a low-rise building as defined in Sec 2.1.3.
* (3) The building is enclosed as defined in Sec 2.1.3 and conforms to the windborne debris provisions of Sec 2.4.9.3.
* (4) The building is a regular-shaped building or structure as defined in Sec 2.1.3.
* (5) The building is not classified as a flexible building as defined in Sec 2.1.3.
* (6) The building does not have response characteristics making it subject to a cross wind loading, vortex shedding, instability due to galloping or flutter; and does not have a site location for which channeling effects or buffeting in the wake of upwind obstructions warrant special consideration.
* (7) The building has an approximately symmetrical cross-section in each direction with either a flat roof or a gable or hip roof with g ≤45 .
* (8) The building is exempted from torsional load cases as indicated in Note 5 of Figure 6.2.10, or the torsional load cases defined in Note 5 do not control the design of any of the MWFRSs of the building.
#### 2.4.2.3 Components and cladding
For the design of components and cladding the building must meet all the following conditions:
* (1) The mean roof height ℎ must be less than or equal to 18.3 m (ℎ≤18.3 m).
* (2) The building is enclosed as defined in Sec 2.1.3 and conforms to windborne debris provisions of Sec 2.4.9.3.
* (3) The building is a regular-shaped building or structure as defined in Sec 2.1.3.
* (4) The building does not have response characteristics making it subject to across-wind loading, vortex shedding, instability due to galloping or flutter; and does not have a site location for which channeling effects or buffeting in the wake of upwind obstructions warrant special consideration.
* (5) The building has either a flat roof, a gable roof with g ≤45 , or a hip roof with g ≤27 .
#### 2.4.2.4 Design procedure
* (1) The basic wind speed shall be determined in accordance with Sec 2.4.4. The wind shall be assumed to come from any horizontal direction.
* (2) An importance factor . shall be determined in accordance with Sec 2.4.5.
* (3) An exposure category shall be determined in accordance with Sec 2.4.6.3.
* (4) A height and exposure adjustment coefficient, h shall be determined from Figure 6.2.2.
##### 2.4.2.4.1 Main wind-force resisting system
Simplified design wind pressures, $p_s$, for the MWFRSs of low-rise simple diaphragm buildings represent the net pressures (sum of internal and external) to be applied to the horizontal and vertical projections of building surfaces as shown in Figure 6.2.2. For the horizontal pressures (zones A, B, C, D), $p_s$ is the combination of the windward and leeward net pressures. $p_s$ shall be determined by the following equation:
$$
p_s = \lambda K_{zt}Ip_{s30} \tag{6.2.3}
$$
Where,
$\lambda$ = adjustment factor for building height and exposure from Figure 6.2.2
$K_{zt}$ = topographic factor as defined in Sec 2.4.7 evaluated at mean roof height, $h$
$I$ = importance factor as defined in Sec 2.4.5
$p_{s30} =$ simplified design wind pressure for Exposure A, at $h = 9.1$ m, and for $I = 1.0$, refer to Figure 6-2 of ASCE 7-05.
Minimum Pressures: The load effects of the design wind pressures from this Section shall not be less than the minimum load case from Sec 2.4.2.1 assuming the pressures, $p_s$, for zones A, B, C, and D all equal to + 0.5 kN/m2 , while assuming zones E, F, G, and H all equal to zero kN/m2 .
##### 2.4.2.4.2 Components and cladding
Net design wind pressures, $p_{net}$, for the components and cladding of buildings designed using Method 1 represent the net pressures (sum of internal and external) to be applied normal to each building surface as shown in Figure 6.2.3. $p_{net}$ shall be determined by the following equation:
$$
p_{net} = \lambda K_{zt}Ip_{net30} \tag{6.2.4}
$$
Where,
$\lambda$ = adjustment factor for building height and exposure from Figure 6.2.3
$K_{zt}$ = topographic factor as defined in Sec 2.4.7 evaluated at mean roof height, h
$I$ = importance factor as defined in Sec 2.4.5
$p_{net30} =$ net design wind pressure for Exposure A, at $h = 9.1$ m, and for $I = 1.0$, refer to Figure 6-3 of ASCE 7-05.
Minimum Pressures: The positive design wind pressures, $p_{net}$, from this Section shall not be less than +0.5 kN/m2 , and the negative design wind pressures, $p_{net}$, from this Section shall not be less than −0.5 kN/m2 .
##### 2.4.2.4.3 Air permeable cladding
Design wind loads determined from Figure 6.2.3 shall be used for all air permeable cladding unless approved test data or the recognized literature demonstrate lower loads for the type of air permeable cladding being considered.
### 2.4.3 Method 2: Analytical Procedure
#### 2.4.3.1 Scopes and limitations
A building or other structure whose design wind loads are determined in accordance with this Section shall meet all of the following conditions:
* (1) The building or other structure is a regular-shaped building or structure as defined in Sec 2.1.3.
* (2) The building or other structure does not have response characteristics making it subject to across-wind loading, vortex shedding, instability due to galloping or flutter; or does not have a site location for which channeling effects or buffeting in the wake of upwind obstructions warrant special consideration.
The provisions of this Section take into consideration of the load magnification effect caused by gusts in resonance with along-wind vibrations of flexible buildings or other structures. Buildings or other structures not meeting the requirements of Sec 2.4.2, or having unusual shapes or response characteristics shall be designed using recognized literature documenting such wind load effects or shall use the wind tunnel procedure specified in Sec 2.4.16.
#### 2.4.3.2 Shielding
There shall be no reductions in velocity pressure due to apparent shielding afforded by buildings and other structures or terrain features.
#### 2.4.3.3 Air permeable cladding
Design wind loads determined from Sec 2.4.3 shall be used for air permeable cladding unless approved test data or recognized literature demonstrate lower loads for the type of air permeable cladding being considered.
#### 2.4.3.4 Design procedure
* (1) The basic wind speed and wind directionality factor 0 shall be determined in accordance with Sec 2.4.4.
* (2) An importance factor . shall be determined in accordance with Sec 2.4.5.
* (3) An exposure category or exposure categories and velocity pressure exposure coefficient 0/ or 03, as applicable, shall be determined for each wind direction in accordance with Sec 2.4.6.
* (4) A topographic factor $K_{zt}$ shall be determined in accordance with Sec 2.4.7.
* (5) A gust effect factor , or ,, as applicable, shall be determined in accordance with Sec 2.4.8.
* (6) An enclosure classification shall be determined in accordance with Sec 2.4.9.
* (7) Internal pressure coefficient ,! shall be determined in accordance with Sec 2.4.10.1.
* (8) External pressure coefficients ! or ,!, or force coefficients , as applicable, shall be determined in accordance with Sections 2.4.10.2 or 2.4.10.3, respectively.
* (9) Velocity pressure X/ or X3, as applicable, shall be determined in accordance with Sec 2.4.9.5.
* (10) Design wind load ; or & shall be determined in accordance with Sec 2.4.11.
### 2.4.4 Basic Wind Speed
The basic wind speed, used in the determination of design wind loads on buildings and other structures shall be as given in Figure 6.2.1 except as provided in Sec 2.4.4.1. The wind shall be assumed to come from any horizontal direction.
#### 2.4.4.1 Special wind regions
The basic wind speed shall be increased where records or experience indicate that the wind speeds are higher than those reflected in Figure 6.2.1. Mountainous terrain, gorges, and special regions shall be examined for unusual wind conditions. The authority having jurisdiction shall, if necessary, adjust the values given in Figure 6.2.1 to account for higher local wind speeds. Such adjustment shall be based on adequate meteorological information and other necessary data.
#### 2.4.4.2 Limitation
Tornadoes have not been considered in developing the basic wind-speed distributions.
#### 2.4.4.3 Wind directionality factor
The wind directionality factor, 0 shall be determined from Table 6.2.12. This factor shall only be applied when used in conjunction with load combinations specified in this Chapter.
![Basic wind speed (V, m/s) map of Bangladesh]()
Figure 6.2.1 Basic wind speed (V, m/s) map of Bangladesh
### 2.4.5 Importance Factor
An importance factor, . for the building or other structure shall be determined from Table 6.2.9 based on building and structure categories listed in Sec 1.2.4.
### **2.4.6 Exposure**
For each wind direction considered, the upwind exposure category shall be based on ground surface roughness that is determined from natural topography, vegetation, and constructed facilities.
#### 2.4.6.1 Wind directions and sectors
For each selected wind direction at which the wind loads are to be evaluated, the exposure of the building or structure shall be determined for the two upwind sectors extending 45o either side of the selected wind direction.
The exposures in these two sectors shall be determined in accordance with Sections 2.4.6.2 and 2.4.6.3 and the exposure resulting in the highest wind loads shall be used to represent the winds from that direction.
#### 2.4.6.2 Surface roughness categories
A ground surface roughness within each 45o sector shall be determined for a distance upwind of the site as defined in Sec 2.4.6.3 from the categories defined in the following text, for the purpose of assigning an exposure category as defined in Sec 2.4.6.3.
Surface Roughness A: Urban and suburban areas, wooded areas, or other terrain with numerous closely spaced obstructions having the size of single-family dwellings or larger.
Surface Roughness B: Open terrain with scattered obstructions having heights generally less than 9.1 m. This category includes flat open country, grasslands, and all water surfaces in cyclone prone regions.
Surface Roughness C: Flat, unobstructed areas and water surfaces outside cyclone prone regions. This category includes smooth mud flats and salt flats.
#### 2.4.6.3 Exposure categories
Exposure A: Exposure A shall apply where the ground surface roughness condition, as defined by Surface Roughness A, prevails in the upwind direction for a distance of at least 792 m or 20 times the height of the building, whichever is greater.
Exception: For buildings whose mean roof height is less than or equal to 9.1 m, the upwind distance may be reduced to 457 m.
Exposure B: Exposure B shall apply for all cases where Exposures A or C do not apply.
Exposure C: Exposure C shall apply where the ground surface roughness, as defined by Surface Roughness C, prevails in the upwind direction for a distance greater than 1,524 m or 20 times the building height, whichever is greater. Exposure C shall extend into downwind areas of Surface Roughness A or B for a distance of 200 m or 20 times the height of the building, whichever is greater.
For a site located in the transition zone between exposure categories, the category resulting in the largest wind forces shall be used.
Exception: An intermediate exposure between the preceding categories is permitted in a transition zone provided that it is determined by a rational analysis method defined in the recognized literature.
#### 2.4.6.4 Exposure category for main wind-force resisting system
Buildings and Other Structures: For each wind direction considered, wind loads for the design of the MWFRS determined from Figure 6.2.6 shall be based on the exposure categories defined in Sec 2.4.6.3.
Low-Rise Buildings: Wind loads for the design of the MWFRSs for low-rise buildings shall be determined using a velocity pressure X3 based on the exposure resulting in the highest wind loads for any wind direction at the site where external pressure coefficients ,! given in Figure 6.2.10 are used.
#### 2.4.6.5 Exposure category for components and cladding
Components and cladding design pressures for all buildings and other structures shall be based on the exposure resulting in the highest wind loads for any direction at the site.
#### 2.4.6.6 Velocity pressure exposure coefficient
Based on the exposure category determined in Sec 2.4.6.3, a velocity pressure exposure coefficient $K_z$ or $K_h$, as applicable, shall be determined from Table 6.2.11. For a site located in a transition zone between exposure categories that is near to a change in ground surface roughness, intermediate values of $K_z$ or $K_h$ between those shown in Table 6.2.11, are permitted, provided that they are determined by a rational analysis method defined in the recognized literature.
### 2.4.7 **Topographic** Effects
#### 2.4.7.1 Wind speed-up over hills, ridges and escarpments
Wind speed-up effects at isolated hills, ridges, and escarpments constituting abrupt changes in the general topography located in any exposure category shall be included in the design when buildings and other site conditions and locations of structures meet all of the following conditions:
* (i) The hill, ridge, or escarpment is isolated and unobstructed upwind by other similar topographic features of comparable height for 100 times the height of the topographic feature (100 H) or 3.22 km, whichever is less. This distance shall be measured horizontally from the point at which the height H of the hill, ridge, or escarpment is determined.
* (ii) The hill, ridge, or escarpment protrudes above the height of upwind terrain features within a 3.22 km radius in any quadrant by a factor of two or more.
* (iii)The structure is located as shown in Figure 6.2.4 in the upper one-half of a hill or ridge or near the crest of an escarpment.
* (iv) $H/L_h \geq 0.2$
* (v) $H$ is greater than or equal to 4.5 m for Exposures B and C and 18.3 m for Exposure A.
#### 2.4.7.2 Topographic factor
The wind speed-up effect shall be included in the calculation of design wind loads by using the factor $K_{zt}$:
$$
K_{zt} = (1 + K_1K_2K_3)^2 \tag{6.2.5}
$$
Where, $K_1$, $K_2$, and $K_3$ are given in Figure 6.2.4. If site conditions and locations of structures do not meet all the conditions specified in Sec 2.4.7.1 then $K_{zt}$ = 1.0.
### 2.4.8 Gust Effect Factor
#### 2.4.8.1 Rigid structures
For rigid structures as defined in Sec 2.1.3, the gust-effect factor shall be taken as 0.85 or calculated by the formula:
$$
G = 0.925\frac{1+1.7g_QI_{\bar z}Q}{1+1.7g_vI_{\bar z}} \tag{6.2.6}
$$
$$
I_{\bar z} = c\left(\frac{10}{\bar z}\right)^{1/6} \tag{6.2.7}
$$
Where, $I_{\bar z}=$ the intensity of turbulence at height $\bar z$ where $\bar z =$ the equivalent height of the structure defined as 0.6h, but not less than $z_{min}$ for all building heights $h$. $z_{min}$ and c are listed for each exposure in Table 6.2.10; $g_Q$ and the value of $g_v$ shall be taken as 3.4. The background response Q is given by
$$
Q = \sqrt{\frac{1}{1+0.63\left(\frac{B+h}{L_{\bar z}}\right)^{0.63}}} \tag{6.2.8}
$$
Where, B, h are defined in Sec 2.1.4; and $L_{\bar{z}} =$ the integral length scale of turbulence at the equivalent height given by
$$
L_{\bar z} = l\left(\frac{\bar z}{10}\right)^{\bar\in} \tag{6.2.9}
$$
In which l and $\bar\in$ are constants listed in Table 6.2.10.
#### 2.4.8.2 Flexible or dynamically sensitive structures
For flexible or dynamically sensitive structures as defined in Sec 2.1.3 (natural period greater than 1.0 second), the gust-effect factor shall be calculated by
$$
G_f = 0.925\left(\frac{1+1.7I_{\bar z}\sqrt{g_Q^2Q^2+g_R^2R^2}}{1+1.7g_vI_{\bar z}}\right) \tag{6.2.10}
$$
The value of both $g_Q$ and $g_v$ shall be taken as 3.4 and $g_R$ is given by
$$
g_R = \sqrt{2\ln(3600n_1)} + \frac{0.577}{\sqrt{2\ln(3600n_1)}} \tag{6.2.11}
$$
$R$, the resonant response factor, is given by
$$
R = \sqrt{\frac{1}{\beta}R_nR_hR_B(0.53 + 0.47R_L)} \tag{6.2.12}
$$
$$
R_n = \frac{7.47N_1}{(1+10.3N_1)^{5/3}} \tag{6.2.13}
$$
$$
N_1 = \frac{n_1L_{\bar z}}{\bar V_{\bar z}} \tag{6.2.14}
$$
$$
R_\ell = \frac{1}{\eta} - \frac{1}{2\eta^2}(1-e^{-2\eta}) \text{ for } \eta > 0 \tag{6.2.15a}
$$
$$
R_\ell = 1 \text{ for } \eta = 0 \tag{6.2.15b}
$$
Where, the subscript $\ell$ in Eq. 6.2.15 shall be taken as $h, B$, and $L$, respectively, where $h, B$, and $L$ are defined in Sec 2.1.4.
$n_1 =$ building natural frequency
$R_\ell = R_h$ setting $\eta = 4.6n_1h/\bar V_{\bar z}$
$R_\ell = R_B$ setting $\eta = 4.6n_1B/\bar V_{\bar z}$
$R_\ell = R_L$ setting $\eta = 15.4n_1L/\bar V_{\bar z}$
$\beta =$ damping ratio, percent of critical
$\bar V_{\bar z}=$ mean hourly wind speed at height $\bar z$ determined from Eq. 6.2.16.
$$
\bar V_{\bar z} = \bar b\left(\frac{\bar z}{10}\right)^{\bar\alpha}V \tag{6.2.16}
$$
#### 2.4.8.3 Rational analysis
In lieu of the procedure defined in Sections 2.4.8.1 and 2.4.8.2, determination of the gust-effect factor by any rational analysis defined in the recognized literature is permitted.
#### 2.4.8.4 Limitations
Where combined gust-effect factors and pressure coefficients $(GC_p, GC_{pi}, GC_{pn})$ are given in figures and tables, the gust-effect factor shall not be determined separately.
### 2.4.9 Enclosure Classifications
#### 2.4.9.1 General
For the purpose of determining internal pressure coefficients, all buildings shall be classified as enclosed, partially enclosed, or open as defined in Sec 2.1.3.
#### 2.4.9.2 Openings
A determination shall be made of the amount of openings in the building envelope to determine the enclosure classification as defined in Sec 2.4.9.3.
#### 2.4.9.3 Wind-borne debris
Glazing in buildings located in wind-borne debris regions shall be protected with an impact-resistant covering or be impact-resistant glazing according to the requirements specified in ASTM E1886 and ASTM E1996 or other approved test methods and performance criteria. The levels of impact resistance shall be a function of Missile Levels and Wind Zones specified in ASTM E1886 and ASTM E1996.
Exceptions:
* (i) Glazing in Category II, III, or IV buildings located over 18.3 m above the ground and over 9.2 m above aggregate surface roofs located within 458 m of the building shall be permitted to be unprotected.
* (ii) Glazing in Category I buildings shall be permitted to be unprotected.
#### 2.4.9.4 Multiple classifications
If a building by definition complies with both the “open” and “partially enclosed” definitions, it shall be classified as an “open” building. A building that does not comply with either the “open” or “partially enclosed” definitions shall be classified as an “enclosed” building.
#### 2.4.9.5 Velocity pressure
Velocity pressure, $q_z$ evaluated at height $z$ shall be calculated by the following equation:
$$
q_z = 0.000613K_zK_{zt}K_dV^2I \text{; (kN/m}^2\text{), } V \text{ in m/s} \tag{6.2.17}
$$
Where $K_d$ is the wind directionality factor, $K_z$ is the velocity pressure exposure coefficient defined in Sec 2.4.6.6, $K_{zt}$ is the topographic factor defined in Sec 2.4.7.2, and $q_h$ is the velocity pressure calculated using Eq. 6.2.17 at mean roof height $h$. The numerical coefficient 0.000613 shall be used except where sufficient climatic data are available to justify the selection of a different value of this factor for a design application.
### **2.4.10 Pressure And Force Coefficients**
#### 2.4.10.1 Internal pressure coefficients
Internal Pressure Coefficient. Internal pressure coefficients, $GC_{pi}$ shall be determined from Figure 6.2.5 based on building enclosure classifications determined from Sec 2.4.9.
Reduction Factor for Large Volume Buildings, $R_i$: For a partially enclosed building containing a single, unpartitioned large volume, the internal pressure coefficient, $GC_{pi}$ shall be multiplied by the following reduction factor, $R_i$:
$$
R_i = 1.0 \text{ or, } R_i = 0.5\left(1 + \frac{1}{\sqrt{1+\frac{V_i}{6951A_{og}}}}\right) \leq 1.0 \tag{6.2.18}
$$
Where, $A_{og}$ = total area of openings in the building envelope (walls and roof, in m2)
$V_i$ = unpartitioned internal volume, in m3
Where, 5 total area of openings in the building envelope (walls and roof, in m2 )
#### 2.4.10.2 External pressure coefficients
Main Wind-Force Resisting Systems: External pressure coefficients for MWFRSs $C_p$ are given in Figures 6.2.6 to 6.2.8. Combined gust effect factor and external pressure coefficients, $GC_{pf}$ are given in Figure 6.2.10 for low-rise buildings. The pressure coefficient values and gust effect factor in Figure 6.2.10 shall not be separated.
Components and Cladding : Combined gust effect factor and external pressure coefficients for components and cladding $GC_p$ are given in Figures 6.2.11 to 6.2.17. The pressure coefficient values and gust-effect factor shall not be separated.
#### 2.4.10.3 Force coefficients
Force coefficients $C_f$ are given in Figures 6.2.20 to 6.2.23.
#### 2.4.10.4 Roof overhangs
Main Wind-Force Resisting System: Roof overhangs shall be designed for a positive pressure on the bottom surface of windward roof overhangs corresponding to $C_p = 0.8$ in combination with the pressures determined from using Figures 6.2.6 and 6.2.10.
Components and Cladding: For all buildings, roof overhangs shall be designed for pressures determined from pressure coefficients given in Figure 6.2.11.
#### 2.4.10.5 Parapets
Main Wind-Force Resisting System: The pressure coefficients for the effect of parapets on the MWFRS loads are given in Sec 2.4.12.2.
Components and Cladding: The pressure coefficients for the design of parapet component and cladding elements are taken from the wall and roof pressure coefficients as specified in Sec 2.4.12.3.
### **2.4.11 Design Wind Loads on Enclosed and Partially Enclosed Buildings**
#### 2.4.11.1 General
Sign Convention: Positive pressure acts toward the surface and negative pressure acts away from the surface.
Critical Load Condition: Values of external and internal pressures shall be combined algebraically to determine the most critical load.
Tributary Areas Greater than 65 m2 : Component and cladding elements with tributary areas greater than 65 m2 shall be permitted to be designed using the provisions for MWFRSs.
#### 2.4.11.2 Main wind-force resisting systems
Rigid Buildings of All Heights: Design wind pressures for the MWFRS of buildings of all heights shall be determined by the following equation:
$$
p = qGC_p - q_i(GC_{pi}) \text{ (kN/m}^2\text{)} \tag{6.2.19}
$$
Where,
$q = q_z$ for windward walls evaluated at height $z$ above the ground
$q = q_h$ for leeward walls, side walls, and roofs, evaluated at height $h$
* $q_i = q_h$ for windward walls, side walls, leeward walls, and roofs of enclosed buildings and for negative internal pressure evaluation in partially enclosed buildings.
$q_i = q_z$ for positive internal pressure evaluation in partially enclosed buildings where height $z$ is defined as the level of the highest opening in the building that could affect the positive internal pressure. For buildings sited in wind-borne debris regions, glazing that is not impact resistant or protected with an impact resistant covering, shall be treated as an opening in accordance with Sec 2.4.9.3. For positive internal pressure evaluation, $q_i$ may conservatively be evaluated at height $h$ ($q_i = q_h$)
$G =$ gust effect factor from Sec 2.4.8
* $C_p =$ external pressure coefficient from Figures 6.2.6 or 6.2.8
$GC_{pi} =$ internal pressure coefficient from Figure 6.2.5
$q_h$ and $q_z$ shall be evaluated using exposure defined in Sec 2.4.6.3. Pressure shall be applied simultaneously on windward and leeward walls and on roof surfaces as defined in Figures 6.2.6 and 6.2.8.
Low-Rise Building: Alternatively, design wind pressures for the MWFRS of lowrise buildings shall be determined by the following equation:
$$
p = q_h\left[(GC_{pf}) - (GC_{pi})\right] \text{ (kN/m}^2\text{)} \tag{6.2.20}
$$
Where,
$q_h =$ velocity pressure evaluated at mean roof height h using exposure defined in Sec 2.4.6.3
$GC_{pf} =$ external pressure coefficient from Figure 6.2.10
$GC_{pi} =$ internal pressure coefficient from Figure 6.2.5
Flexible Buildings: Design wind pressures for the MWFRS of flexible buildings shall be determined from the following equation:
$$
p = qG_fC_p - q_i(GC_{pi}) \text{ (kN/m}^2\text{)} \tag{6.2.21}
$$
Where, $q$, $q_i$, $C_p$, and $GC_{pi}$ are as defined in Sec 2.4.11.2 and $G_f =$ gust effect factor is defined as in Sec 2.4.8.
Parapets: The design wind pressure for the effect of parapets on MWFRSs of rigid, low-rise, or flexible buildings with flat, gable, or hip roofs shall be determined by the following equation:
$$
p_p = q_pGC_{pn} \text{ (kN/m}^2\text{)} \tag{6.2.22}
$$
Where,
* $p_p =$ Combined net pressure on the parapet due to the combination of the net pressures from the front and back parapet surfaces. Plus (and minus) signs signify net pressure acting toward (and away from) the front (exterior) side of the parapet
* $q_p =$ Velocity pressure evaluated at the top of the parapet
$GC_{pn} =$ Combined net pressure coefficient
\= +1.5 for windward parapet
\= −1.0 for leeward parapet
#### 2.4.11.3 Design wind load cases
The MWFRS of buildings of all heights, whose wind loads have been determined under the provisions of Sec 2.4.11.2, shall be designed for the wind load cases as defined in Figure 6.2.9. The eccentricity $e$ for rigid structures shall be measured from the geometric center of the building face and shall be considered for each principal axis $(e_x, e_y)$. The eccentricity $e$ for flexible structures shall be determined from the following equation and shall be considered for each principal axis $(e_x, e_y)$:
$$
e = \frac{e_Q+1.7I_{\bar z}\sqrt{(g_QQe_Q)^2+(g_RRe_R)^2}}{1+1.7I_{\bar z}\sqrt{(g_QQ)^2+(g_RR)^2}} \tag{6.2.23}
$$
Where,
$e_Q =$ Eccentricity e as determined for rigid structures in Figure 6.2.9
$e_R =$ Distance between the elastic shear center and center of mass of each floor
$I_{\bar z}, g_Q, Q, g_R, R$ shall be as defined in Sec 2.1.4
The sign of the eccentricity $e$ shall be plus or minus, whichever causes the more severe load effect.
Exception: One-story buildings with h less than or equal to 9.1 m, buildings two stories or less framed with light-frame construction, and buildings two stories or less designed with flexible diaphragms need only be designed for Load Case 1 and Load Case 3 in Figure 6.2.9.
#### 2.4.11.4 Components and cladding.
Low-Rise Buildings and Buildings with ℎ≤18.3 m: Design wind pressures on component and cladding elements of low-rise buildings and buildings with ℎ≤ 18.3 m shall be determined from the following equation:
$$
p = q_h\left[(GC_p) - (GC_{pi})\right] \text{ (kN/m}^2\text{)} \tag{6.2.24}
$$
Where,
$q_h =$ Velocity pressure evaluated at mean roof height ℎ using exposure defined in Sec 2.4.6.5
$GC_p =$ External pressure coefficients given in Figures 6.2.11 to 6.2.16
$GC_{pi} =$ Internal pressure coefficient given in Figure 6.2.5
Buildings with ℎ> 18.3 m: Design wind pressures on components and cladding for all buildings with ℎ> 18.3 m shall be determined from the following equation:
$$
p = q(GC_p) - q_i(GC_{pi}) \text{ (kN/m}^2\text{)} \tag{6.2.25}
$$
Where,
$q = q_z$ for windward walls calculated at height 4 above the ground
$q = q_h$ for leeward walls, side walls, and roofs, evaluated at height ℎ
$q_i = q_h$ for windward walls, side walls, leeward walls, and roofs of enclosed buildings and for negative internal pressure evaluation in partially enclosed buildings
$q_i = q_z$ for positive internal pressure evaluation in partially enclosed buildings where height 4 is defined as the level of the highest opening in the building that could affect the positive internal pressure. For buildings sited in wind-borne debris regions, glazing that is not impact resistant or protected with an impact-resistant covering, shall be treated as an opening in accordance with Sec 2.4.9.3. For positive internal pressure evaluation, qi may conservatively be evaluated at height ℎ ($q_i = q_h$)
$(GC_p) =$ external pressure coefficient from Figure 6.2.17.
$(GC_{pi}) =$ internal pressure coefficient given in Figure 6.2.5. $q_h$ and $q_z$ shall be evaluated using exposure defined in Sec 2.4.6.3.
#### 2.4.11.5 Alternative design wind pressures for components and cladding in buildings with 18.3 m \< ℎ\< 27.4 m.
Alternative to the requirements of Sec 2.4.11.2, the design of components and cladding for buildings with a mean roof height greater than 18.3 m and less than 27.4 m values from Figures 6.2.11 to 6.2.17 shall be used only if the height to width ratio is one or less (except as permitted by Notes of Figure 6.2.17) and Eq. 6.2.24 is used.
Parapets: The design wind pressure on the components and cladding elements of parapets shall be designed by the following equation:
$$
p = q_p(GC_p - GC_{pi}) \tag{6.2.26}
$$
Where,
X! 5 Velocity pressure evaluated at the top of the parapet
,! 5 External pressure coefficient from Figures 6.2.11 to 6.2.17
,! 5 Internal pressure coefficient from Figure 6.2.5, based on the porosity of the parapet envelope.
Two load cases shall be considered. Load Case A shall consist of applying the applicable positive wall pressure from Figures 6.2.11 or 6.2.17 to the front surface of the parapet while applying the applicable negative edge or corner zone roof pressure from Figures 6.2.11 to 6.2.17 to the back surface. Load Case B shall consist of applying the applicable positive wall pressure from Figures 6.2.11 or 6.2.17 to the back of the parapet surface, and applying the applicable negative wall pressure from Figures 6.2.11 or 6.2.17 to the front surface. Edge and corner zones shall be arranged as shown in Figures 6.2.11 to 6.2.17. ,! shall be determined for appropriate roof angle and effective wind area from Figures 6.2.11 to 6.2.17. If internal pressure is present, both load cases should be evaluated under positive and negative internal pressure.
### **2.4.12 Design Wind Loads on Open Buildings with Monoslope, Pitched, or Troughed Roofs**
#### 2.4.12.1 General
Sign Convention: Plus and minus signs signify pressure acting toward and away from the top surface of the roof, respectively.
Critical Load Condition: Net pressure coefficients CN include contributions from top and bottom surfaces. All load cases shown for each roof angle shall be investigated.
#### 2.4.12.2 Main wind-force resisting systems
The net design pressure for the MWFRSs of monoslope, pitched, or troughed roofs shall be determined by the following equation:
Where,
* X3 5 Velocity pressure evaluated at mean roof height h using the exposure as defined in Sec 2.4.6.3 that results in the highest wind loads for any wind direction at the site
* , 5 Gust effect factor from Sec 2.4.8
* 5 Net pressure coefficient determined from Figures 6.2.18(a) to 6.2.18(d).
For free roofs with an angle of plane of roof from horizontal g less than or equal to 5o and containing fascia panels, the fascia panel shall be considered an inverted parapet. The contribution of loads on the fascia to the MWFRS loads shall be determined using Sec 2.4.11.5 with X! equal to X3 .
#### 2.4.12.3 Component and cladding elements
The net design wind pressure for component and cladding elements of monoslope, pitched, and troughed roofs shall be determined by the following equation:
Where,
* X3 5 Velocity pressure evaluated at mean roof height ℎ using the exposure as defined in Sec 2.4.6.3 that results in the highest wind loads for any wind direction at the site
* , 5 Gust-effect factor from Sec 2.4.8
* 5 Net pressure coefficient determined from Figures 6.2.19(a) to 6.2.19(c).
### **2.4.13 Design Wind Loads on Solid Free Standing Walls and Solid Signs**
The design wind force for solid freestanding walls and solid signs shall be determined by the following formula:
Where,
* X3 5 Velocity pressure evaluated at height ℎ (Figure 6.2.20) using exposure defined in Sec2.4.6.3
* , 5 Gust-effect factor from Sec 2.4.8
* 5 Net force coefficient from Figure 6.2.20
* 5 Gross area of the solid freestanding wall or solid sign, in m2
### **2.4.14 Design Wind Loads on Other Structures**
The design wind force for other structures shall be determined by the following equation:
$$
F = q_zGC_fA_f \text{ (kN)} \tag{6.2.30}
$$
Where,
* $q_z$ = Velocity pressure evaluated at height $z$ of the centroid of area $A_f$ using exposure as in Sec 2.4.6.3
* $G$ = Gust-effect factor from Sec 2.4.8
* $C_f$ = Force coefficients from Figures 6.2.21 to 6.2.23.
* $A_f$ = Projected area normal to the wind except where $C_f$ is specified for the actual surface area, m2
### **2.4.15 Rooftop Structures and Equipment for Buildings with h ≤ 18.3 m**
The force on rooftop structures and equipment with $A_f$ less than $(0.1Bh)$ located on buildings with $h \le 18.3$ m shall be determined from Eq. 6.2.30, increased by a factor of 1.9. The factor shall be permitted to be reduced linearly from 1.9 to 1.0 as the value of $A_f$ is increased from $(0.1Bh)$ to $(Bh)$.
### 2.4.16 Method 3 - Wind Tunnel Procedure
#### 2.4.16.1 Scope
Wind tunnel tests shall be used where required by Sec 2.4.3.1. Wind tunnel testing shall be permitted in lieu of Methods 1 and 2 for any building or structure.
#### 2.4.16.2 Test conditions
Wind tunnel tests, or similar tests employing fluids other than air, used for the determination of design wind loads for any building or other structure, shall be conducted in accordance with this Section. Tests for the determination of mean and fluctuating forces and pressures shall meet all of the following conditions:
* (i) Natural atmospheric boundary layer has been modeled to account for the variation of wind speed with height.
* (ii) The relevant macro- (integral) length and micro-length scales of the longitudinal component of atmospheric turbulence are modeled to approximately the same scale as that used to model the building or structure.
* (iii) The modeled building or other structure and surrounding structures and topography are geometrically similar to their full-scale counterparts, except that, for low-rise buildings meeting the requirements of Sec 2.4.3.1, tests shall be permitted for the modeled building in a single exposure site as in Sec 2.4.6.
* (iv) The projected area of the modeled building or other structure and surroundings is less than 8 percent of the test section cross-sectional area unless correction is made for blockage.
* (v) The longitudinal pressure gradient in the wind tunnel test section is accounted for.
* (vi) Reynolds number effects on pressures and forces are minimized.
* (vii) Response characteristics of the wind tunnel instrumentation are consistent with the required measurements.
### 2.4.17 Dynamic Response
Tests for the purpose of determining the dynamic response of a building or other structure shall be in accordance with Sec 2.4.16.2. The structural model and associated analysis shall account for mass distribution, stiffness, and damping.
**Enclosed Buildings: Walls & Roofs**
Notes:
1. Pressures shown are applied to the horizontal and vertical projections, for exposure A, at *h* =9.1m *, I* =1.0, and *Kzt* = 1.0. Adjust to other conditions using Equation 6.2.3.
2. The load patterns shown shall be applied to each corner of the building in turn as the reference corner. (See Figure 6.2.10)
3. For the design of the longitudinal MWFRS use θ = 0°, and locate the zone E/F, G/H boundary at the mid-length of the building.
4. Load cases 1 and 2 must be checked for 25° \< θ ≤ 45°. Load case 2 at 25° is provided only for interpolation between 25° to 30°.
5. Plus and minus signs signify pressures acting toward and away from the projected surfaces, respectively.
6. For roof slopes other than those shown, linear interpolation is permitted.
7. The total horizontal load shall not be less than that determined by assuming *ps* = 0 in zones B & D.
8. The zone pressures represent the following:
* Horizontal pressure zones – Sum of the windward and leeward net (sum of internal and external) pressures on vertical projection of:
* *A* - End zone of wall *C* - Interior zone of wall
* *B* - End zone of roof *D* - Interior zone of roof
* Vertical pressure zones – Net (sum of internal and external) pressures on horizontal projection of:
* *E* - End zone of windward roof *G* - Interior zone of windward roof
*F* - End zone of leeward roof *H* - Interior zone of leeward roof
9. Where zone E or G falls on a roof overhang on the windward side of the building, use EOH and GOH for the pressure on the horizontal projection of the overhang. Overhangs on the leeward and side edges shall have the basic zone pressure applied.
10. Notation:
*a* : 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension or 0.9 m.
*h* : Mean roof height, in feet (meters), except that eave height shall be used for roof angles \<10°.
*θ:* Angle of plane of roof from horizontal, in degrees.
| **Adjustment Factor for Bu** | **ilding Height an** | \*\*d Exposure,\*\*λ | |
| ---------------------------- | -------------------- | -------------------- | ----- |
| **Mean roof height (m)** | | **Exposure** | |
| | **A** | **B** | **C** |
| 4.6 | 1.00 | 1.21 | 1.47 |
| 6.0 | 1.00 | 1.29 | 1.55 |
| 7.6 | 1.00 | 1.35 | 1.61 |
| 9.1 | 1.00 | 1.40 | 1.66 |
| 10.7 | 1.05 | 1.45 | 1.70 |
| 12.2 | 1.09 | 1.49 | 1.74 |
| 13.7 | 1.12 | 1.53 | 1.78 |
| 15.2 | 1.16 | 1.56 | 1.81 |
| 16.8 | 1.19 | 1.59 | 1.84 |
| 18.3 | 1.22 | 1.62 | 1.87 |
![Design wind pressure for main wind force resisting system - Method 1 (h ≤ 18.3 m)]()
**Figure 6.2.2 Design wind pressure for main wind force resisting system- Method 1 (** ***h* ≤ 18.3 m)**
**Enclosed Buildings: Walls & Roofs**
**Notes:**
1. Pressures shown are applied normal to the surface, for exposure A, at *h* = 9.1m, *I* = 1.0, and *Kzt* = 1.0. Adjust to other conditions using Equation 6.2.4.
2. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively. 3. For hip roofs with θ ≤ 25°, Zone 3 shall be treated as Zone 2.
3. For effective wind areas between those given, value may be interpolated, otherwise use the value associated with the lower effective wind area. 5. Notation:
* *a* : 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension or 0.9 m.
* *h* : Mean roof height, in feet (meters), except that eave height shall be used for roof angles \<10°. *θ* : Angle of plane of roof from horizontal, in degrees.
| | | **Roof Overha**
**(E**
| **ng Net**
**xposure** | **Design**
**A at\*\*\*\**h*** | **Wind Pr**
**= 9.1 m**
| **essure,**
**with\*\*\*\**l*=**
| ***Pnet30* (kN/m****2****)**
**1.0)**
| | |
| --------- | -------- | ------------------------------------- | --------------------------- | ----------------------------------- | ---------------------------------- | ------------------------------------------- | ------------------------------------------------------------ | --------- | --------- |
| **Roof** | **Zone** | **Effective** | | | **Basic** | **Wind S** | **peed V(m/s)** | | |
| **Pitch** | | **Wind area (m****2****)** | **40.23** | **44.7** | **49.17** | **53.64** | **58.11 62.58** | **67.05** | **75.99** |
| | **2** | 0.930 | -1.005 | -1.239 | -1.502 | -1.785 | -2.096 -2.431 | -2.790 | -3.584 |
| | **2** | 1.860 | -0.986 | -1.220 | -1.473 | -1.756 | -2.058 -2.388 | -2.742 | -3.522 |
| **rees** | **2** | 4.648 | -0.962 | -1.191 | -1.440 | -1.713 | -2.010 -2.330 | -2.675 | -3.436 |
| **7 deg** | **2** | 9.296 | -0.947 | -1.168 | -1.412 | -1.680 | -1.971 -2.287 | -2.627 | -3.373 |
| **0 to** | **3** | 0.930 | -1.656 | -2.043 | -2.470 | -2.943 | -3.450 -4.005 | -4.594 | -5.905 |
| **Roof** | **3** | 1.860 | -1.297 | -1.603 | -1.938 | -2.311 | -2.708 -3.144 | -3.609 | -4.632 |
| | **3** | 4.648 | -0.828 | -1.024 | -1.240 | -1.474 | -1.727 -2.005 | -2.302 | -2.957 |
| | **3** | 9.296 | -0.479 | -0.584 | -0.708 | -0.842 | -0.986 -1.144 | -1.311 | -1.684 |
![Design wind pressure for components and cladding - Method 1 (h ≤ 18.3 m)]()
**Figure 6.2.3 Design wind pressure for components and cladding - Method 1 (** ***h* ≤ 18.3 m)**
| | **Ro**
| **of Overha**
**(Ex**
| **ng Net**
**posure** | **Design**
**A at\*\*\*\**h*** | **Wind**
**= 9.1**
| **Pressu**
**m with**
| **re,\*\*\*\**Pnet3***
***l*= 1.0)**
| ***0* (kN/**
| **m****2****)** | |
| ---------- | ------------ | ---------------------------------------------- | -------------------------- | ----------------------------------- | ----------------------------- | -------------------------------- | ------------------------------------------------ | ------------------- | -------------------------- | --------- |
| **Roof** | **Zone** | **Effective** | | | **Basic** | **Wind** | **Speed V** | **(m/s)** | | |
| **Pitch** | | **Wind area**
**(m****2****)** | **40.23** | **44.7** | **49.17** | **53.64** | **58.11** | **62.58** | **67.05** | **75.99** |
| | **2** | 0.930 | -1.302 | -1.603 | -1.943 | -2.311 | -2.713 | -3.144 | -3.613 | -4.637 |
| | **2** | 1.860 | -1.302 | -1.603 | -1.943 | -2.311 | -2.713 | -3.144 | -3.613 | -4.637 |
| **egrees** | **2** | 4.648 | -1.302 | -1.603 | -1.943 | -2.311 | -2.713 | -3.144 | -3.613 | -4.637 |
| **27 d** | **2** | 9.296 | -1.302 | -1.603 | -1.943 | -2.311 | -2.713 | -3.144 | -3.613 | -4.637 |
| **> 7 to** | **3** | 0.930 | -2.187 | -2.699 | -3.268 | -3.885 | -4.560 | -5.292 | -6.072 | -7.800 |
| **Roof** | **3** | 1.860 | -1.971 | -2.436 | -2.948 | -3.507 | -4.115 | -4.775 | -5.479 | -7.039 |
| | **3** | 4.648 | -1.689 | -2.086 | -2.526 | -3.005 | -3.526 | -4.091 | -4.694 | -6.034 |
| | **3** | 9.296 | -1.479 | -1.823 | -2.206 | -2.627 | -3.082 | -3.574 | -4.106 | -5.268 |
| | **2** | 0.930 | -1.182 | -1.460 | -1.766 | -2.101 | -2.464 | -2.861 | -3.282 | -4.216 |
| **s** | **2** | 1.860 | -1.148 | -1.416 | -1.713 | -2.038 | -2.393 | -2.775 | -3.182 | -4.091 |
| **egree** | **2** | 4.648 | -1.101 | -1.359 | -1.641 | -1.952 | -2.292 | -2.660 | -3.052 | -3.924 |
| **45 d** | **2** | 9.296 | -1.062 | -1.311 | -1.587 | -1.890 | -2.220 | -2.574 | -2.952 | -3.795 |
| **27 to** | **3** | 0.930 | -1.182 | -1.460 | -1.766 | -2.101 | -2.464 | -2.861 | -3.283 | -4.216 |
| **oof >** | **3** | 1.860 | -1.148 | -1.416 | -1.713 | -2.038 | -2.393 | -2.775 | -3.182 | -4.091 |
| **R** | **3** | 4.648 | -1.101 | -1.359 | -1.641 | -1.952 | -2.292 | -2.660 | -3.053 | -3.923 |
| | **3** | 9.296 | -1.062 | -1.311 | -1.589 | -1.890 | -2.220 | -2.574 | -2.952 | -3.795 |
| **Adjustment Factor for Bu** | **ilding Height an** | \*\*d Exposure,\*\*λ | |
| ---------------------------- | -------------------- | -------------------- | ----- |
| **Mean roof height (m)** | | **Exposure** | |
| | **A** | **B** | **C** |
| 4.6 | 1.00 | 1.21 | 1.47 |
| 6.1 | 1.00 | 1.29 | 1.55 |
| 7.6 | 1.00 | 1.35 | 1.61 |
| 9.15 | 1.00 | 1.40 | 1.66 |
| 10.7 | 1.05 | 1.45 | 1.70 |
| 12.2 | 1.09 | 1.49 | 1.74 |
| 13.7 | 1.12 | 1.53 | 1.78 |
| 15.2 | 1.16 | 1.56 | 1.81 |
| 16.8 | 1.19 | 1.59 | 1.84 |
| 18.3 | 1.22 | 1.62 | 1.87 |
**Unit Conversion – 1.0 ft =0.3048 m; 1.0 ft****2**\*\* = 0.0929 m\*\***2****; 1.0 psf = 0.0479 kN/m****2**
![Design wind pressure for components and cladding - Method 1 Contd (h ≤ 18.3 m)]()
**Figure 6.2.3 (Contd.) Design wind pressure for components and cladding-Method 1 (** ***h* ≤ 18.3 m)**
| | | | **Topogra**
| **phic M**
| **ultiplier**
| **s for Ex**
| **posure**
| **B**
| | |
| ---------- | ---------------------- | ------------------------ | -------------------------------------- | ---------------- | ------------------------ | ------------------------------------- | ---------------- | ---------------------- | ------------------------ | -------------------------------------- |
| ***H/Lh*** | ***K*** | ***1* Multipl** | **er** | ***x/Lh*** | ***K2* Mul** | **tiplier** | ***z/Lh*** | | ***3* Multipl** | **ier** |
| | **2-D**
**Ridge** | **2-D**
**Escarp.** | **3-D**
**Axisym.**
**Hill** | | **2-D**
**Escarp.** | **All**
**Other**
**Cases** | | **2-D**
**Ridge** | **2-D**
**Escarp.** | **3-D**
**Axisym.**
**Hill** |
| 0.20 | 0.29 | 0.17 | 0.21 | 0.00 | 1.00 | 1.00 | 0.00 | 1.00 | 1.00 | 1.00 |
| 0.25 | 0.36 | 0.21 | 0.26 | 0.50 | 0.88 | 0.67 | 0.10 | 0.74 | 0.78 | 0.67 |
| 0.30 | 0.43 | 0.26 | 0.32 | 1.00 | 0.75 | 0.33 | 0.20 | 0.55 | 0.61 | 0.45 |
| 0.35 | 0.51 | 0.30 | 0.37 | 1.50 | 0.63 | 0.00 | 0.30 | 0.41 | 0.47 | 0.30 |
| 0.40 | 0.58 | 0.34 | 0.42 | 2.00 | 0.50 | 0.00 | 0.40 | 0.30 | 0.37 | 0.20 |
| 0.45 | 0.65 | 0.38 | 0.47 | 2.50 | 0.38 | 0.00 | 0.50 | 0.22 | 0.29 | 0.14 |
| 0.50 | 0.72 | 0.43 | 0.53 | 3.00 | 0.25 | 0.00 | 0.60 | 0.17 | 0.22 | 0.09 |
| | | | | 3.50 | 0.13 | 0.00 | 0.70 | 0.12 | 0.17 | 0.06 |
| | | | | 4.00 | 0.00 | 0.00 | 0.80 | 0.09 | 0.14 | 0.04 |
| | | | | | | | 0.90 | 0.07 | 0.11 | 0.03 |
| | | | | | | | 1.00 | 0.05 | 0.08 | 0.02 |
| | | | | | | | 1.50 | 0.01 | 0.02 | 0.00 |
| | | | | | | | 2.00 | 0.00 | 0.00 | 0.00 |
| Notes: | | | | | | | | | | |
1. For values of *H/Lh* , *x/Lh* and *z/Lh* other than those shown, linear interpolation is permitted. 2. For *H/Lh* > 0.5, assume *H/Lh* = 0.5 for evaluating *K* 1 and substitute *2H* for *Lh* for evaluating *K* 2 and *K* 3.
2. Multipliers are based on the assumption that wind approaches the hill or escarpment along the direction of maximum slope.
3. Notation:
*H* : Height of hill or escarpment relative to the upwind terrain, in meters. *Lh* : Distance upwind of crest to where the difference in ground elevation is half the height of hill or escarpment, in meters.
* *K1* : Factor to account for shape of topographic feature and maximum speed-up effect.
* *K2* : Factor to account for reduction in speed-up with distance upwind or downwind of crest.
* *K3* : Factor to account for reduction in speed-up with height above local terrain. *x* : Distance (upwind or downwind) from the crest to the building site, in meters.
*z* : Height above local ground level, in meters. *W* : Horizontal attenuation factor. *γ* : Height attenuation factor Equation: 0PÒë//B /" 5 (1 + 0Á 1 0 02 ) ; K1 determined from Table below; 0 5 ¸1 − êB||Á¹ ; 02 5
| **Parame** | **ters for Spee** | **d-Up Over H** | **ills and Esca** | **rpme** | **nts** | |
| ------------------------------------ | ------------------- | ------------------- | ----------------- | -------- | ---------------------------- | ------------------------------------ |
| **Hill Shape** | | **\_K1/(H/Lh) \_** | | ***γ*** | ***μ*** | |
| | \*\*Exposure A \*\* | \*\*Exposure B \*\* | **Exposure C** | | **Upwind of**
**crest** |
**Downwind**
**of Crest** |
| 2-dimensional ridges | 1.30 | 1.45 | 1.55 | 3 | 1.5 | 1.5 |
| (or valleys with negative | | | | | | |
| *H\_in\_K1/(H/Lh*) | | | | | | |
| 2-dimensional | 0.75 | 0.85 | 0.95 | 2.5 | 1.5 | 4 |
| escarpments | | | | | | |
| 3-dimensional
axisym.
Hill | 0.95 | 1.05 | 1.15 | 4 | 1.5 | 1.5 |
![Topographic factor, Kzt - Method 2]()
**Figure 6.2.4 Topographic factor,** ***Kzt* - Method 2**
**Enclosed, Partially Enclosed, and Open Buildings: Walls & Roofs**
| **Enclosure Classification** | ***GCpi*** | Notes: |
| ---------------------------- | ---------------- | ---------------------------------------------------------------------------------------------------------------------------- |
| Open Building | 0.00 | 1. Plus and minus signs signify pressures acting
|
| Partially Enclosed Building | +0.55
-0.55 | toward and away from the internal surfaces,
respectively.
2. Values of\_GCpi\_shall be used with\_qz\_or\_qh \_as |
| Enclosed Building | +0.18 | specified in Sec 2.4.11. |
| | -0.18 | 3. Two cases shall be considered to determine the |
| | | critical load requirements for the appropriate |
| | | condition: |
| | | (i) a positive value of\_GCpi \_applied to all internal
surfaces |
| | | (ii) a negative value of\_GCpi \_applied to all internal
surfaces. |
![Internal pressure coefficient, GCpi main wind force resisting system component and cladding - Method 2 (All Heights)]()
**Figure 6.2.5 Internal pressure coefficient, GCpi main wind force resisting system component and cladding - Method 2 (All Heights)**
![External Pressure Coefficients, Cp main wind force resisting system - Method 2 (All Heights)]()
**Figure 6.2.6 External Pressure Coefficients, Cp main wind force resisting system - Method 2 (All Heights)**
| **Wind**
| | **Roo** | **f Press** | **ure Co**
**Win** | **efficie**
**dward** | **nts,\*\*\*\**Cp***
| **, for u** | **se with** | ***qh*** | | **Leewa** | **rd** |
| ------------------------------- | ------ | ------------------- | ---------------------- | ----------------------- | -------------------------- | -------------------------- | --------------- | ---------------- | --------------- | ------------- | ------------------ | ----------------- |
| **Direction** | | | **A**
| **ngle, θ**
| **(degr**
| **ees)**
| | | | **Ang**
| **le, θ (d**
| **egrees)**
|
| | *h/L* | 10 | 15 | 20 | 25 | 30 | 35 | 45 | >60# | 10 | 15 | >20 |
| Normal
To ridge for
| \<0.25 | -0.7
-0.18 | -0.5
0.0\* | -0.3
0.2 | -0.2
0.3 | -0.2
0.3 | 0.0\*
0.4 | 0.4 | 0.01θ | -0.3 | -0.5 | -0.6 |
| θ>100 | 0.5 | -0.9
-0.18 | -0.7
-0.18 | -0.4
0.0\* | -0.3
0.2 | -0.2
0.2 | -0.2
0.3 | 0.0\*
0.4 | 0.01θ | -0.5 | -0.5 | -0.6 |
| | >1.0 | -1.3\*\*
-0.18 | -1.0
-0.18 | -0.7
-0.18 | -0.5
0.0\* | -0.3
0.2 | -0.2
0.2 | 0.0\*
0.3 | 0.01θ | -0.7 | -0.6 | -0.6 |
| Normal
To ridge for | | Horizo
from W | ntal dist
indward | ance
edge | *C* | *p* | \* Val
pur | ue is
poses | provid | ed fo | r inter | polation |
| θ \<10oand
| | 0 | to\_h/2\_ | | -0.9, | -0.18 | \*\* Va
| lue can
| be redu
| ced li
| nearly w
| ith area
|
| Parallel to
ridge for all | \<0.5 | *h* | */2\_to\_h* | | -0.9, | -0.18 | ove | r whic | it is app | licabl | e as foll | ows |
| θ | | *h* | to\_2 h\_ | | -0.5, | -0.18 | | | | | | |
| | | | > 2h | | -0.3, | -0.18 | | | | | | |
| | | | | | \*\* | | | Area ( | m2) | R | eductio | n Factor |
| | >1.0 | | to\_h/2\_ | | -1.3 | ,-0.18 | | \<9. | 3 | | 1. | 0 |
| | | | | | | | | 23. | 2 | | 0. | 9 |
| | | | >*h/2* | | -0.7, | -0.18 | | >92 | .9 | | 0. | 8 |
| **Notes:** | | | | | | | | | | | | |
1. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
2. Linear interpolation is permitted for values of *L/B, h/L* and θ other than shown. Interpolation shall only be carried out between values of the same sign. Where no value of the same sign is given, assume 0.0 for interpolation purposes.
3. Where two values of *Cp* are listed, this indicates that the windward roof slope is subjected to either positive or negative pressures and the roof structure shall be designed for both conditions. Interpolation for intermediate ratios of *h/L* in this case shall only be carried out between C *p* values of like sign. 4. For monoslope roofs, entire roof surface is either a windward or leeward surface. 5. For flexible buildings use appropriate *Gf* as determined by Sec 2.4.8. 6. Refer to Figure 6.2.7 for domes and Figure 6.2.8 for arched roofs. 7. Notation: *B* : Horizontal dimension of building, in meter, measured normal to wind direction. *L* : Horizontal dimension of building, in meter, measured parallel to wind direction. *h* : Mean roof height in meters, except that eave height shall be used for e 10 degrees. *z* : Height above ground, in meters. *G* : Gust effect factor. *q* z, *qh* : Velocity pressure, in N/m2 , evaluated at respective height. θ: Angle of plane of roof from horizontal, in degrees. 8. For mansard roofs, the top horizontal surface and leeward inclined surface shall be treated as leeward surfaces from the table 9. Except for MWFRS's at the roof consisting of moment resisting frames, the total horizontal shear shall not be less than that determined by neglecting wind forces on roof surfaces. #For roof slopes greater than 80°, use *Cp* = 0.8
![External pressure coefficients, Cp main wind force resisting system - Method 2 Contd (All Heights)]()
**Figure 6.2.6 (Contd.) External pressure coefficients,** ***Cp* main wind force resisting system - Method 2 (All Heights)**
**Enclosed, Partially Enclosed Buildings and Structures: Domed Roofs**
Notes:
1. Two load cases shall be considered:
* Case A. Cp values between A and B and between B and C shall be determined by linear interpolation along arcs on the dome parallel to the wind direction;
* Case B. Cp shall be the constant value of A for θ ≤ 25 degrees, and shall be determined by linear interpolation from 25 degrees to B and from B to C.
2. Values denote Cp to be used with $q_h$ where (hD + f) is the height at the top of the dome.
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Cp is constant on the dome surface for arcs of circles perpendicular to the wind direction; for example, the arc passing through B-B-B and all arcs parallel to B-B-B.
5. For values of hD/D between those listed on the graph curves, linear interpolation shall be permitted.
6. θ50 degrees on dome springline, θ590 degrees at dome center top point. f is measured from springline to top.
7. The total horizontal shear shall not be less than that determined by neglecting wind forces roof surfaces.
8. For f/D values less than 0.05, use Figure 6.2.6.
![External pressure coefficients, Cp main wind force resisting system - Method 2 (All Heights)]()
**Figure 6.2.7 External pressure coefficients, Cp main wind force resisting system - Method 2 (All Heights)**
**Enclosed, Partially Enclosed Buildings and Structures: Arched Roofs**
| **Condition** | **Rise-to-span** | | ***Cp*** | |
| ------------------------------------- | --------------------- | ----------------------------- | ------------------------ | ---------------------------- |
| | **ratio,\*\*\*\**r*** | **Windward**
**quarter** | **Center**
**half** | **Leeward**
**quarter** |
| | 0 \<*r*\< 0.2 | -0.9 | -0.7 -*r* | -0.5 |
| Roof on elevated
structure | 0.2 ≤*r*\< 0.3\* | l.5\_r\_- 0.3 | -0.7 -*r* | -0.5 |
| | 0.3 ≤*r*≤ 0.6 | 2.75\_r\_- 0.7 | -0.7 -*r* | -0.5 |
| Roof springing from
ground level | 0 \<*r*≤ 0.6 | 1.4\_r\_ | -0.7 -*r* | -0.5 |
| **Notes:** | | | | |
* When the rise-to-span ratio is 0.2 ≤ *r* ≤ 0.3, alternate coefficients given by (6 *r* - 2.1) shall also be used for the windward quarter.
1. Values listed are for the determination of average load on main wind force resisting systems.
2. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
3. For wind directed parallel to the axis of the arch, use pressure coefficients from Figure 6.2.6 with wind directed parallel to ridge.
4. For components and cladding: (1) At roof perimeter, use the external pressure coefficients in Figure 6.2.11 with *e* based on spring-line slope and (2) for remaining roof areas, use external pressure coefficients of this Table multiplied by 0.87.
![External pressure coefficients, Cp main wind force resisting system component and cladding - Method 2 (All Heights)]()
**Figure 6.2.8 External pressure coefficients, Cp main wind force resisting system component and cladding - Method 2 (All Heights)**
* Case 1. Full design wind pressure acting on the projected area perpendicular to each principal axis of the structure, considered separately along each principal axis.
* Case 2. Three quarters of the design wind pressure acting on the projected area perpendicular to each principal axis of the structure in conjunction with a torsional moment as shown, considered separately for each principal axis.
* Case 3. Wind loading as defined in Case 1, but considered to act simultaneously at 75% of the specified value.
* Case 4. Wind loading as defined in Case 2, but considered to act simultaneously at 75% of the specified value.
**Notes:**
1. Design wind pressures for windward and leeward faces shall be determined in accordance with the provisions of Sec 2.4.11 as applicable for building of all heights.
2. Diagrams show plan views of building. 3. Notation: *Pwx, PwY:* Windward face design pressure acting in the *x, y* principal axis, respectively.
*PLX, PLY:* Leeward face design pressure acting in the *x, y* principal axis, respectively.
*e* ( *ex, ey* ): Eccentricity for the *x, y* principal axis of the structure, respectively. *MT* : Torsional moment per unit height acting about a vertical axis of the building.
![Design wind load cases for main wind force resisting system - Method 2 (All Heights)]()
**Figure 6.2.9 Design wind load cases for main wind force resisting system-Method 2 (All Heights)**
![External pressure coefficients, GCpf for main wind force resisting system - Method 2 (h ≤ 18.3 m)]()
**Figure 6.2.10 External pressure coefficients, GCpf for main wind force resisting system- Method 2 (h ≤ 18.3 m)**
**Enclosed, Partially Enclosed Buildings: Low-rise Walls & Roofs**
| **Roof**
**Angle θ**
| | | | | **Bu** | **ilding S** | **urface** | | | |
| ------------------------------- | ----- | ----- | ----- | ----- | ------ | ------------ | ---------- | ------ | ------ | ------ |
| **(degrees)** | **1** | **2** | **3** | **4** | **5** | **6** | **1E** | **2E** | **3E** | **4E** |
| 0-5 | 0.40 | -0.69 | -0.37 | -0.29 | -0.45 | -0.45 | 0.61 | -1.07 | -0.53 | -0.43 |
| 20 | 0.53 | -0.69 | -0.48 | -0.43 | -0.45 | -0.45 | 0.80 | -1.07 | -0.69 | -0.64 |
| 30-45 | 0.56 | 0.21 | -0.43 | -0.37 | -0.45 | -0.45 | 0.69 | 0.27 | -0.53 | -0.48 |
| 90 | 0.56 | 0.56 | -0.37 | -0.37 | -0.45 | -0.45 | 0.69 | 0.69 | -0.48 | -0.48 |
| Notes: | | | | | | | | | | |
1. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
2. For values of θ other than those shown, linear interpolation is permitted.
3. The building must be designed for all wind directions using the 8 loading patterns shown. The load patterns are applied to each building corner in turn as the Reference Corner.
4. Combinations of external and internal pressures (see Figure 6.2.5) shall be evaluated as required to obtain the most severe loadings.
5. For the torsional load cases shown below, the pressures in zones designated with a “T” (1T, 2T, 3T, 4T) shall be 25% of the full design wind pressures (zones 1, 2, 3, 4). Exception: One story buildings with h less than or equal to 9.1m, buildings two stories or less framed with light frame construction, and buildings two stories or less designed with flexible diaphragms need not be designed for the torsional load cases.
* Torsional loading shall apply to all eight basic load patterns using the figures below applied at each reference corner.
6. Except for moment-resisting frames, the total horizontal shear shall not be less than that determined by neglecting wind forces on roof surfaces.
7. For the design of the MWFRS providing lateral resistance in a direction parallel to a ridge line or for flat roofs, use θ 5 0° and locate the zone 2/3 boundary at the mid-length of the building.
8. The roof pressure coefficient GCpf, when negative in Zone 2 or 2E, shall be applied in Zone 2/2E for a distance from the edge of roof equal to 0.5 times the horizontal dimension of the building parallel to the direction of the MWFRS being designed or 2.5 times the eave height, he, at the windward wall, whichever is less; the remainder of Zone 2/2E extending to the ridge line shall use the pressure coefficient GCpf for Zone 3/3E.
9. Notation:
* a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension or 0.9 m. h: Mean roof height, in meters, except that eave height shall be used for θ ≤ 10°. θ: Angle of plane of roof from horizontal, in degrees.
![External pressure coefficients, GCpf for main wind force resisting system - Method 2 Contd (h ≤ 18.3 m)]()
**Figure 6.2.10 (Contd.) External pressure coefficients, GCpf for main wind force resisting system - Method 2 (h ≤ 18.3 m)**
**Enclosed, Partially Enclosed Buildings: Walls**
**Notes:**
1. Vertical scale denotes *GCP* to be used with *qh.*
2. Horizontal scale denotes effective wind area, in square meters.
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. Values of *GCP* for walls shall be reduced by 10% when θ ≤ 100 .
6. Notation:
* *a:* 10 percent of least horizontal dimension or *0.4h* , whichever is smaller, but not less than either 4% of least horizontal dimension or 0.9m.
* *h:* Mean roof height, in meters, except that eave height shall be used for θ ≤ 100 . θ: Angle of plane of roof from horizontal, in degrees.
![External pressure coefficients, GCp for components and cladding – Method 2 - Walls (h ≤ 18.3 m)]()
**Figure 6.2.11(a) External pressure coefficients, GCp for components and cladding–Method 2 (h ≤ 18.3 m)**
1. Vertical scale denotes *GCP* to be used with *qh.*
2. Horizontal scale denotes effective wind area, in square meters.
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. If a parapet equal to or higher than 0.9 m is provided around the perimeter of the roof with θ ≤ 70 , the negative values of *GCp* in Zone 3 shall be equal to those for Zone 2 and positive values of *GCP* in Zones 2 and 4 shall be set equal to those for wall Zones 4 and 5 respectively in Figure 6.2.11(a).
6. Values of *GCP* for roof overhangs include pressure contributions from both upper and lower surfaces.
7. Notation:
* *a:* 10 percent of least horizontal dimension or *0.4h* , whichever is smaller, but not less than either 4% of least horizontal dimension or 0.9 m.
* *h:* Eave height shall be used for θ ≤ 100 .
* θ: Angle of plane of roof from horizontal, in degrees.
![External pressure coefficients, GCp for components and cladding – Method 2 - Gable Roofs θ ≤ 7° (h ≤ 18.3 m)]()
**Figure 6.2.11(b) External pressure coefficients, GCp for components and cladding– Method 2 (h ≤ 18.3 m)**
**Enclosed, Partially Enclosed Buildings: Gable/Hip Roofs 7****0** **\< θ ≤ 27****0**
Notes:
1. Vertical scale denotes GCP to be used with *q h*
2. Horizontal scale denotes effective wind area, in square feet (square meters).
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. Values of GCP for roof overhangs include pressure contributions from both upper and lower surfaces.
6. For hip roofs with 70 \< θ ≤ 270 , edge/ridge strips and pressure coefficients for ridges of gabled roofs shall apply on each hip.
7. For hip roofs with 70 \< θ ≤ 250 , Zone 3 shall be treated as Zone 2.
8. Notation:
* a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension or 0.9 m.
* h: Mean roof height, in meters, except that eave height shall be used for θ ≤ 100 .
θ: Angle of plane of roof from horizontal, in degrees.
![External pressure coefficients, GCp for components and cladding – Method 2 - Gable/Hip Roofs 7° < θ ≤ 27°]()
**Figure 6.2.11(c) External pressure coefficients, GCp for components and cladding–Method 2**
**(h ≤ 18.3 m)**
1. Vertical scale denotes GCP to be used with qh. 2. Horizontal scale denotes effective wind area, in square feet (square meters).
2. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
3. Each component shall be designed for maximum positive and negative pressures.
4. Values of GCP for roof overhangs include pressure contributions from both upper and lower surfaces.
5. Notation: a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension or 0.9m.
h: Mean roof height, in meters. θ: Angle of plane of roof from horizontal, in degrees.
![External pressure coefficients, GCp for components and cladding – Method 2 - Gable Roofs 27° < θ ≤ 45° (h ≤ 18.3 m)]()
**Figure 6.2.11(d) External pressure coefficients, GCp for components and cladding–Method 2 (h ≤ 18.3 m)**
Notes:
On the lower level of flat, stepped roofs shown in Figure 6.2.12, the zone designations and pressure coefficients shown in Figure 6.2.11(b) shall apply, except that at the roof-upper wall intersection(s), Zone 3 shall be treated as Zone 2 and Zone 2 shall be treated as Zone 1. Positive values of GCp equal to those for walls in Figure 6.2.11(a) shall apply on the cross-hatched areas shown in Figure 6.2.12.
Notation:
b: 1.5h1 in Figure 6.2.12, but not greater than 30.5 m.
h: Mean roof height, in meters.
hi: h1 or h2 in Figure 6.2.12; h 5 h1 + h2; h1≥ 3.1 m; hi/h 5 0.3 to 0.7.
W: Building width in Figure 6.2.12.
Wi: W1or W2 or W3 in Figure 6.2.12. W5 W1 + W2or W1 + W2 + W3; Wi/W5 0.25 to 0.75.
e: Angle of plane of roof from horizontal, in degrees.
![External pressure coefficients, GCp for components and cladding – Method 2 - Stepped Roofs (h ≤ 18.3 m)]()
**Figure 6.2.12 External pressure coefficients, GCp for components and cladding–Method 2 (h ≤ 18.3 m)**
**Enclosed, Partially Enclosed Buildings: Multispan Gable Roofs**
**Notes:**
1. Vertical scale denotes *GCP* to be used with *qh.*
2. Horizontal scale denotes effective wind area, in square meters.
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. For θ ≤ 100 Values of *GCP* from Figure 6.2.11 shall be used. 6. Notation:
* *a:* 10 percent of least horizontal dimension or 0.4 *h* , whichever is smaller, but not less than either 4% of least horizontal dimension or 0.9 m.
* *h:* Mean roof height, in feet (meters), except that eave height shall be used for *θ* ≤ 100 .
*W* : Building module width, in meters.
* θ: Angle of plane of roof from horizontal, in degrees.
![External pressure coefficients, GCp for components and cladding – Method 2 - Multispan Gable Roofs (h ≤ 18.3 m)]()
**Figure 6.2.13 External pressure coefficients, GCp for components and cladding–Method 2 (h ≤ 18.3 m)**
**Enclosed, Partially Enclosed Buildings: Monoslope Roofs 3****0** **\<** ***θ* ≤ 10****0z**
Notes:
1. Vertical scale denotes GCP to be used with qh.
2. Horizontal scale denotes effective wind area A, in square meters.
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. For θ ≤ 30° Values of GCP from Figure 6.2.11(b) shall be used.
6. Notation:
* a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension or 0.9 m.
* h: Eave height shall be used for θ ≤ 100 .
* W: Building width, in meters.
θ: Angle of plane of roof from horizontal, in degrees.
![External pressure coefficients, GCp for components and cladding – Method 2 - Monoslope Roofs 3° < θ ≤ 10° (h ≤ 18.3 m)]()
**Figure 6.2.14(a) External pressure coefficients, GCp for components and cladding– Method 2 (h ≤ 18.3 m)**
**Enclosed, Partially Enclosed Buildings: Monoslope Roofs 10****0** **\<** ***θ* ≤ 30****0**
Notes:
1. Vertical scale denotes GCP to be used with qh
2. Horizontal scale denotes effective wind area A, in square feet (square meters).
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. Notation:
* a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension or 0.9 m.
* h: Mean roof height in meters.
* W: Building width, in meters.
* θ: Angle of plane of roof from horizontal, in degrees.
![External pressure coefficients, GCp for components and cladding – Method 2 - Monoslope Roofs 10° < θ ≤ 30° (h ≤ 18.3 m)]()
**Figure 6.2.14(b) External pressure coefficients, GCp for components and cladding– Method 2 (h ≤ 18.3 m)**
**Enclosed, Partially Enclosed Buildings: Sawtooth Roofs**
1. Vertical scale denotes GCP to be used with qh.
2. Horizontal scale denotes effective wind area A, in square feet (square meters).
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. For θ≤100 Values of GCP from Figure 6.2.11 shall be used.
6. Notation:
* a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension or 0.9 m.
* h: Mean roof height in meters except that eave height shall be used for θ≤ 100 . W: Building width, in meters.
* θ: Angle of plane of roof from horizontal, in degrees.
![External pressure coefficients, GCp for components and cladding – Method 2 - Sawtooth Roofs (h ≤ 18.3 m)]()
**Figure 6.2.15 External pressure coefficients, GCp for components and cladding– Method 2 (h ≤ 18.3 m)**
**Enclosed, Partially Enclosed Buildings: Domed Roofs**
| **External Pressure Coefficients for Domes w** | **ith a circular Base** | |
| ---------------------------------------------- | ----------------------- | ---------------------- |
| θ d
**Negative Pressures** | **Positive Pressures** | **Positive Pressures** |
| , egrees
0 – 90 | 0 – 60 | 61 – 90 |
| GCp
-0.9 | +0.9 | +0.5 |
| **Notes:** | | |
1. Values denote Cp to be used with q(hD+f) where hD+f is the height at the top of the dome.
2. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
3. Each component shall be designed for maximum positive and negative pressures.
4. Values apply to θ ≤ hDD ≤ 0.5, 0.2≤ f/D ≤0.5.
5. θ 50o on dome springline, θ 5 90o at dome center top point. f is measured from springline to top.
![External pressure coefficients, GCp for components and cladding – Method 2 - Domed Roofs (All heights)]()
**Figure 6.2.16 External pressure coefficients, GCp for components and cladding – Method 2 (All heights)**
*1.* Vertical scale denotes *GCp* to be used with appropriate *qz* or *qh.*
* 2.Horizontal scale denotes effective wind area \_A in square feet (square meters).
* 3.Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
*4.* Use *qz* with positive values of *GCp* and *qh* with negative values of *GCp*
* 5.Each component shall be designed for maximum positive and negative pressures.
* 6.Coefficients are for roofs with angle θ≤10°. For other roof angles and geometry, use *GCp* values from Figure 6.2.11 and attendant *qh* based on exposure defined in Sec 2.4.6.
* 7.If a parapet equal to or higher than 0.9 m is provided around the perimeter of the roof with θ≤10° Zone 3 shall be treated as Zone 2.
* 8.Notation:
*a:* 10 percent of least horizontal dimension, but not less than 0.9 m.
* *h:* Mean roof height, in meters, except that eave height shall be used for θ≤10o .
* *z:* height above ground, in (meters).
θ: Angle of plane of roof from horizontal, in degrees.
![External pressure coefficients, GCp for components and cladding – Method 2 - Walls & Roofs (All heights)]()
**Figure 6.2.17 External pressure coefficients, GCp for components and cladding – Method 2 (h ≤ 18.3 m)**
**Open Buildings: Monoslope free roofs (** ***q*** **\< 45** ° **,** γ **= 0** ° **, 180** ° **)**
| **Roof** | **Load** | **Wi** | **nd Dire** | **ction, **γ**=** | **0**° | Win | d Direc | tion, γ= | 180° |
| ---------------- | -------- | --------------------- | -------------------- | ----------------------- | ----------------------- | -------------- | ----------- | ---------------- | --------------- |
| **Angle**
θ | **Case** | **Clear**
**Fl** | **Wind**
**ow** | **Obstr**
**Wind** | **ucted**
**Flow** | Clear
Flo | Wind
w | Obstruct
Fl | ed Wind
ow |
| | | **CNW** | **CNL** | **CNW** | **CNL** | CNW | CNL | CNW | CNL |
| 0° | A | 1.2 | 0.3 | -0.5 | -1.2 | 1.2 | 0.3 | -0.5 | -1.2 |
| | B | -1.1 | -0.1 | -1.1 | -0.6 | -1.1 | -0.1 | -1.1 | -0.6 |
| 75° | A | -0.6 | -1 | -1 | -1.5 | 0.9 | 1.5 | -0.2 | -1.2 |
| . | B | -1.4 | 0 | -1.7 | -0.8 | 1.6 | 0.3 | 0.8 | -0.3 |
| 15° | A | -0.3 | -1.3 | -1.1 | -1.5 | 1.3 | 1.6 | 0.4 | -1.1 |
| | B | -1.9 | 0 | -2.1 | -0.6 | 1.8 | 0.6 | 1.2 | -0.3 |
| 225° | A | -1.5 | -1.6 | -1.5 | -1.7 | 1.7 | 1.8 | 0.5 | -1 |
| . | B | -2.4 | -0.3 | -2.3 | -0.9 | 2.2 | 0.7 | 1.3 | 0 |
| 30° | A | -1.8 | -1.8 | -1.5 | -1.8 | 2.1 | 2.1 | 0.6 | -1 |
| | B | -2.5 | -0.6 | -2.3 | -1.1 | 2.6 | 1 | 1.6 | 0.1 |
| ° | A | -1.8 | -1.8 | -1.5 | -1.8 | 2.1 | 2.2 | 0.7 | -0.9 |
| 37.5 | B | -2.4 | -0.6 | -2.2 | -1.1 | 2.7 | 1.1 | 1.9 | 0.3 |
| ° | A | -1.6 | -1.8 | -1.3 | -1.8 | 2.2 | 2.5 | 0.8 | -0.9 |
| 45 | B | -2.3 | -0.7 | -1.9 | -1.2 | 2.6 | 1.4 | 2.1 | 0.4 |
| **Notes:** | | | | | | | | | |
1. *CNW* and *CNL* denote net pressures (contributions from top and bottom surfaces) for windward and leeward half of roof surfaces, respectively.
2. Clear wind flow denotes relatively unobstructed wind flow with blockage less than or equal to 50%. Obstructed wind flow denotes objects below roof inhibiting wind flow (>50% blockage).
3. For values of e between 7.5° and 45°, linear interpolation is permitted. For values of e less than 7.5°, use Monoslope roof load coefficients.
4. Plus and minus signs signify pressures acting towards and away from the top roof surface, respectively.
5. All load cases shown for each roof angle shall be investigated.
6. Notation:
L : horizontal dimension of roof, measured in the along wind direction, m
* h : mean roof height, m γ : direction of wind, degrees θ : angle of plane of roof from horizontal, degrees
![Net pressure coefficient, CN for main wind force resisting system - Monoslope free roofs (0.25 ≤ h/L ≤ 1.0)]()
**Figure 6.2.18(a) Net pressure coefficient,** ***CN* for main wind force resisting system (0.25\<** ***h/L*** **\< 1.0)**
**Open Buildings: Pitched Free Roofs (** θ **≤ 45****o** **,** ***γ* = 0****o** **, 180****o** **)**
| Roof | Load | | Wind Directi | on,ð 5 0o, 180 | o |
| --------------- | ---- | -------- | ------------ | ------------------------- | ------------ |
| Angle,θ | Case | Clear Wi | nd Flow | Obstructed | Wind Flow |
| | | CNW | CNL | CNW | CNL |
| 75o | A | 1.1 | -0.3 | -1.6 | -1 |
| . | B | 0.2 | -1.2 | -0.9 | -1.7 |
| 15o | A | 1.1 | -0.4 | -1.2 | -1 |
| | B | 0.1 | -1.1 | -0.6 | -1.6 |
| 225o | A | 1.1 | 0.1 | -1.2 | -1.2 |
| . | B | -0.1 | -0.8 | -0.8 | -1.7 |
| 30o | A | 1.3 | 0.3 | -0.7 | -0.7 |
| | B | -0.1 | -0.9 | -0.2 | -1.1 |
| 375o | A | 1.3 | 0.6 | -0.6 | -0.6 |
| . | B | -0.2 | -0.6 | -0.3 | -0.9 |
| 45o | A | 1.1 | 0.9 | -0.5 | -0.5 |
| | B | -0.3 | -0.5 | -0.3 | -0.7 |
| Notes: | | | | | |
1. CNW and CNL denote net pressures (contributions from top and bottom surfaces) for windward and leeward half of roof surfaces, respectively.
2. Clear wind flow denotes relatively unobstructed wind flow with blockage less than or equal to 50%. Obstructed wind flow denotes objects below roof inhibiting wind flow (>50% blockage).
3. For values of θ between 7.5° and 45°, linear interpolation is permitted. For values of θ less than 7.5°, use monoslope roof load coefficients.
4. Plus and minus signs signify pressures acting towards and away from the top roof surface, respectively.
5. All load cases shown for each roof angle shall be investigated.
6. Notation:
L : horizontal dimension of roof, measured in the along wind direction, m
* h : mean roof height, m
γ : direction of wind, degrees
* : angle of plane of roof from horizontal, degrees
![Net pressure coefficient, CN for main wind force resisting system - Pitched free roofs (0.25 ≤ h/L ≤ 1.0)]()
**Figure 6.2.18(b) Net pressure coefficient,** ***CN* for main wind force resisting system (0.25\<** ***h/L*** **\< 1.0)**
| **Roof** | **Load** | | **Wind Direc** | **tion, γ=0****o,****180****o** | |
| --------------- | -------- | ------------ | -------------- | ----------------------------------------------------- | ------------- |
| \*\*Angle,\*\*θ | **Case** | **Clear Wi** | **nd Flow** | **Obstructed** | **Wind Flow** |
| | | ***CNW*** | ***CNL*** | ***CNW*** | ***CNL*** |
| 75o | A | -1.1 | 0.3 | -1.6 | -0.5 |
| . | B | -0.2 | 1.2 | -0.9 | -0.8 |
| 15o | A | -1.1 | 0.4 | -1.2 | -0.5 |
| | B | 0.1 | 1.1 | -0.6 | -0.8 |
| 225o | A | -1.1 | -0.1 | -1.2 | -0.6 |
| . | B | -0.1 | 0.8 | -0.8 | -0.8 |
| 30o | A | -1.3 | -0.3 | -1.4 | -0.4 |
| | B | -0.1 | 0.9 | -0.2 | -0.5 |
| 375o | A | -1.3 | -0.6 | -1.4 | -0.3 |
| . | B | 0.2 | 0.6 | -0.3 | -0.4 |
| 45o | A | -1.1 | -0.9 | -1.2 | -0.3 |
| | B | 0.3 | 0.5 | -0.3 | -0.4 |
* Notes: 1. CNW and CNL denote net pressures (contributions from top and bottom surfaces) for windward and leeward half of roof surfaces, respectively.
2. Clear wind flow denotes relatively unobstructed wind flow with blockage less than or equal to 50%. Obstructed wind flow denotes objects below roof inhibiting wind flow (>50% blockage).
3. For values of θ between 7.5° and 45°, linear interpolation is permitted. For values of θ less than 7.5°, use monoslope roof load coefficients.
4. Plus and minus signs signify pressures acting towards and away from the top roof surface, respectively.
5. All load cases shown for each roof angle shall be investigated.
6. Notation:
* L : horizontal dimension of roof, measured in the along wind direction, m
* h : mean roof height, m
* γ : direction of wind, degrees θ : angle of plane of roof from horizontal, degrees
![Net pressure coefficient, CN for main wind force resisting system - Troughed free roofs (0.25 ≤ h/L ≤ 1.0)]()
**Figure 6.2.18(c) Net pressure coefficient,** ***CN* for main wind force resisting system (0.25\<** ***h/L*** **\< 1.0)**
| **Horizontal**
**Distance from** | **Roof**
**Angle**θ | **Load Case** | **Clear**
**Wind Flow** | **Obstructed**
**Wind Flow** |
| ------------------------------------- | ------------------------ | ------------- | ---------------------------- | --------------------------------- |
| \*\*Windward Edge \*\* | | | ***CN*** | ***CN*** |
| *h* | All Shapes | A | -0.8 | -1.2 |
| ≤ | θ≤ 45o | B | 0.8 | 0.5 |
| >*h* *2h* | All Shapes | A | -0.6 | -0.9 |
| , ≤ | θ≤ 45o | B | 0.5 | 0.5 |
| >*2h* | All Shapes | A | -0.3 | -0.6 |
| | θ≤ 45o | B | 0.3 | 0.3 |
| Notes: | | | | |
1. CN denotes net pressures (contributions from top and bottom surfaces).
2. Clear wind flow denotes relatively unobstructed wind flow with blockage less than or equal to 50%. Obstructed wind flow denotes objects below roof inhibiting wind flow (>50% blockage).
3. Plus and minus signs signify pressures acting towards and away from the top roof surface, respectively.
4. All load cases shown for each roof angle shall be investigated.
5. For monoslope roofs with theta less than 5 degrees, CN values shown apply also for cases where gamma 5 0 degrees and 0.05 less than or equal to h/L less than or equal to 0.25. See Figure 6.2.18(a) for other h/L values.
6. Notation:
* L : horizontal dimension of roof, measured in the along wind direction, m
* h : mean roof height, m
y : direction of wind, degrees
* : angle of plane of roof from horizontal, degrees
![Net pressure coefficient, CN for main wind force resisting system - Troughed free roofs Contd (0.25 ≤ h/L ≤ 1.0)]()
**Figure 6.2.18(d) Net pressure coefficient,** ***CN* for main wind force resisting system (0.25\<** ***h/L*** **\< 1.0)**
**Open Buildings: Monoslope Free Roofs (** θ **\< 45** ° **)**
| **Roof**
**Angle**
θ | **Effective**
**Wind Area** | | **Cle** | **ar Wi** | **nd Flo** | **w** | ***C*** | ***N*** | **Obstr** | **ucted** | **Wind** | **Flow** | |
| ------------------------------ | ------------------------------------------- | ------- | ------- | --------- | ---------- | ------- | ------- | ------- | --------- | --------- | -------- | -------- | ------- |
| | | **Zon** | **e 3** | **Zon** | **e 2** | **Zon** | **e 1** | **Zon** | **e 3** | **Zon** | **e 2** | **Zon** | **e 1** |
| ° | \< *a**2* | 2.4 | -3.3 | 1.8 | -1.7 | 1.2 | -1.1 | 1 | -3.6 | 0.8 | -1.8 | 0.5 | -1.2 |
| 0 | >*a**2*,\<4.0\_a\_*2* | 1.8 | -1.7 | 1.8 | -1.7 | 1.2 | -1.1 | 0.8 | -1.8 | 0.8 | -1.8 | 0.5 | -1.2 |
| | >4.0\_a\_*2* | 1.2 | -1.1 | 1.2 | -1.1 | 1.2 | -1.1 | 0.5 | -1.2 | 0.5 | -1.2 | 0.5 | -1.2 |
| | \<*a**2* | 3.2 | -4.2 | 2.4 | -2.1 | 1.6 | -1.4 | 1.6 | -5.1 | 0.5 | -2.6 | 0.8 | -1.7 |
| 7.5° | >*a**2*,\<4.0\_a\_*2* | 2.4 | -2.1 | 2.4 | -2.1 | 1.6 | -1.4 | 1.2 | -2.6 | 1.2 | -2.6 | 0.8 | -1.7 |
| | >4.0\_a\_*2* | 1.6 | -1.4 | 1.6 | -1.4 | 1.6 | -1.4 | 0.8 | -1.7 | 0.8 | -1.7 | 0.8 | -1.7 |
| | \<*a**2* | 3.6 | -3.8 | 2.7 | -2.9 | 1.8 | -1.9 | 2.4 | -4.2 | 1.8 | -3.2 | 1.2 | -2.1 |
| 15° | >*a**2*,\<4.0\_a\_*2* | 2.7 | -2.9 | 2.7 | -2.9 | 1.8 | -1.9 | 1.8 | -3.2 | 1.8 | -3.2 | 1.2 | -2.1 |
| | >4.0\_a\_*2* | 1.8 | -1.9 | 1.8 | -1.9 | 1.8 | -1.9 | 1.2 | -2.1 | 1.2 | -2.1 | 1.2 | -2.3 |
| | \<*a**2* | 5.2 | -5 | 3.9 | -3.8 | 2.6 | -2.5 | 3.2 | -4.6 | 2.4 | -3.5 | 1.6 | -2.3 |
| 30° | >*a**2*,\<4.0\_a\_*2* | 3.9 | -3.8 | 3.9 | -3.8 | 2.6 | -2.5 | 2.4 | -3.5 | 2.4 | -3.5 | 1.6 | -2.3 |
| | >4.0\_a\_*2* | 2.6 | -2.5 | 2.6 | -2.5 | 2.6 | -2.5 | 1.6 | -2.3 | 1.6 | -2.3 | 1.6 | -2.3 |
| | \<*a**2* | 5.2 | -4.6 | 3.9 | -3.5 | 2.6 | -2.3 | 4.2 | -3.8 | 3.2 | -2.9 | 2.1 | -1.9 |
| 45° | >*a**2*,\<4.0\_a\_*2* | 3.9 | -3.5 | 3.9 | -3.5 | 2.6 | -2.3 | 3.2 | -2.9 | 3.2 | -2.9 | 2.1 | -1.9 |
| | >4.0\_a\_*2* | 2.6 | -2.3 | 2.6 | -2.3 | 2.6 | -2.3 | 2.1 | -1.9 | 2.1 | -1.9 | 2.1 | -1.9 |
| Notes: | | | | | | | | | | | | | |
1. CNdenotes net pressures (contributions from top and bottom surfaces).
2. Clear wind flow denotes relatively unobstructed wind flow with blockage less than or equal to 50% wind flow denotes objects below roof inhibiting wind flow (>50% blockage).
3. For values of e other than those shown, linear interpolation is permitted.
4. Plus and minus signs signify pressures acting towards and away from the top roof surface, respectively.
5. Components and cladding elements shall be designed for positive and negative pressure coefficients shown.
6. Notation:
* : 10% of least horizontal dimension or 0.4h, whichever is smaller but not less than
* 4% of least horizontal dimension or 0.9 m h : mean roof height, m L : horizontal dimension of building, measured in along wind direction, m θ: angle of plane of roof from horizontal, degrees
![Net pressure coefficient, CN for components and cladding - Monoslope free roofs θ ≤ 7.5° (0.25 ≤ h/L ≤ 1.0)]()
**Figure 6.2.19(a) Net pressure coefficient,** ***CN* for components and cladding (0.25\<** ***h/L*** **\< 1.0)**
![Net pressure coefficient, CN for components and cladding - Monoslope free roofs 7.5° < θ ≤ 45° (0.25 ≤ h/L ≤ 1.0)]()
Figure 6.2.19(b) Net pressure coefficient, CN for components and cladding (0.25\< h/L \< 1.0)
![Net pressure coefficient, CN for components and cladding - Troughed free roofs θ ≤ 45° (0.25 ≤ h/L ≤ 1.0)]()
**Figure 6.2.19(c) Net pressure coefficient,** ***CN* for components and cladding (0.25\<** ***h/L*** **\< 1.0)**
**Notes:**
1. The term "signs" in notes below also applies to "freestanding walls".
2. Signs with openings comprising less than 30% of the gross area are classified as solid signs. Force coefficients for solid signs with openings shall be permitted to be multiplied by the reduction factor (1 - (1 - ε)1.5 ).
3. To allow for both normal and oblique wind directions, the following cases shall be considered:
For s/h \< 1:
* CASE A: resultant force acts normal to the face of the sign through the geometric center.
CASE B: resultant force acts normal to the face of the sign at a distance from the geometric center toward the windward edge equal to 0.2 times the average width of the sign.
For B/s ≥ 2, CASE C must also be considered:
CASE C: resultant forces act normal to the face of the sign through the geometric centers of each region.
For s/h 5 1:
The same cases as above except that the vertical locations of the resultant forces occur at a distance above the geometric center equal to 0.05 times the average height of the sign.
4. For CASE C where s/h > 0.8, force coefficients shall be multiplied by the reduction factor (1.8 - s/h). 5. Linear interpolation is permitted for values of s/h, B/s and Lr/s other than shown. 6. Notation: B: horizontal dimension of sign, in meters; h : height of the sign, in meters; s: vertical dimension of the sign, in meters; ε: ratio of solid area to gross area; Lr: horizontal dimension of return corner, in meters
![Force Coefficient, Cf for solid freestanding walls and solid signs - Method 2 (All heights)]()
**Figure 6.2.20 Force Coefficient, Cf for other structures - Method 2 (All heights)**
**Chimneys, Tanks, Rooftop Equipment, & Similar Structures**
| Cross-Section | Type of Surface | | h/D | |
| -------------------------------------------------------------- | --------------------------- | --- | --- | --- |
| | | 1 | 7 | 25 |
| Square (wind normal to face) | All | 1.3 | 1.4 | 2.0 |
| Square (wind along diagomal) | All | 1.0 | 1.1 | 1.5 |
| Hexagonal or octagonal | All | 1.0 | 1.2 | 1.4 |
| Round | Moderately smooth | 0.5 | 0.6 | 0.7 |
| #tX/
> 5.3, # in m, | Rough (D’/D50.02) | 0.7 | 0.8 | 0.9 |
| X/in N m
⁄ | Very rough
(D’/D50.08) | 0.8 | 1.0 | 0.2 |
| Round
#tX/
≤5.3, # in m,
X/in N m
⁄ | All | 0.7 | 0.8 | 1.2 |
| Notes: | | | | |
1. The design wind force shall be calculated based on the area of the structure projected on a plane normal to the wind direction. The force shall be assumed to act parallel to the wind direction.
2. Linear interpolation is permitted for h/D values other than shown.
3. Notation:
* D : diameter of circular cross-section and least horizontal dimension of square, hexagonal or octagonal cross-section at elevation under consideration, in meters;
* D’: depth of protruding element such as ribs and spoilers, in meters;
* H: height of structure, meters and
* qz: velocity pressure evaluated at height z above ground, in N/m2
![Force coefficient, Cf for chimneys, tanks, rooftop equipment - Method 2 (All heights)]()
**Figure 6.2.21 Force coefficient, Cf for other structures - Method 2 (All heights)**
| **Open Signs & Latt** | **ice Frameworks** | | |
| --------------------- | ------------------ | ----------------- | ----------------- |
| ∈ | Flat-Sided Members | Rounded | Members |
| | | D/t
≤ 0.05 | D/t
> 0.05 |
| \<0.1 | 2.0 | 1.2 | 0.8 |
| 0.1 to 0.29 | 1.8 | 1.3 | 0.9 |
| 0.3 to 0.7 | 1.6 | 1.5 | 1.1 |
* Notes: 1. Signs with openings comprising 30% or more of the gross area are classified as open signs.
* 2. The calculation of the design wind forces shall be based on the area of all exposed members and elements projected on a plane normal to the wind direction. Forces shall be assumed to act parallel to the wind.
* 3. The area Af consistent with these force coefficients is the solid area projected normal the wind direction.
* 4. Notation: ∈ : ratio of solid area to gross area; D: diameter of a typical round number, in meters qz: velocity pressure evaluated at height z above ground in N/m2 .
![Force coefficient, Cf for open signs and lattice frameworks - Method 2 (All heights)]()
**Figure 6.2.22 Force coefficient, Cf for other structures - Method 2 (All heights)**
**Table 6.2.8: Basic Wind Speeds,** ***V* , for Selected Locations in Bangladesh**
| **Location** | **Basic Wind** | **Location** | **Basic Wind** |
| ---------------------------------- | -------------- | ------------------- | -------------- |
| | **Speed(m/s)** | | **Speed(m/s)** |
| Angarpota | 47.8 | Lalmonirhat | 63.7 |
| Bagerhat | 77.5 | Madaripur | 68.1 |
| Bandarban | 62.5 | Magura | 65.0 |
| Barguna | 80.0 | Manikganj | 58.2 |
| Barisal | 78.7 | Meherpur | 58.2 |
| Bhola | 69.5 | Maheshkhali | 80.0 |
| Bogra | 61.9 | Moulvibazar | 53.0 |
| Brahmanbaria | 56.7 | Munshiganj | 57.1 |
| Chandpur | 50.6 | Mymensingh | 67.4 |
| Chapai Nawabganj | 41.4 | Naogaon | 55.2 |
| Chittagong | 80.0 | Narail | 68.6 |
| Chuadanga | 61.9 | Narayanganj | 61.1 |
| Comilla | 61.4 | Narsinghdi | 59.7 |
| Cox’s Bazar | 80.0 | Natore | 61.9 |
| Dahagram | 47.8 | Netrokona | 65.6 |
| Dhaka | 65.7 | Nilphamari | 44.7 |
| Dinajpur | 41.4 | Noakhali | 57.1 |
| Faridpur | 63.1 | Pabna | 63.1 |
| Feni | 64.1 | Panchagarh | 41.4 |
| Gaibandha | 65.6 | Patuakhali | 80.0 |
| Gazipur | 66.5 | Pirojpur | 80.0 |
| Gopalganj | 74.5 | Rajbari | 59.1 |
| Habiganj | 54.2 | Rajshahi | 49.2 |
| Hatiya | 80.0 | Rangamati | 56.7 |
| Ishurdi | 69.5 | Rangpur | 65.3 |
| Joypurhat | 56.7 | Satkhira | 57.6 |
| Jamalpur | 56.7 | Shariatpur | 61.9 |
| Jessore | 64.1 | Sherpur | 62.5 |
| Jhalakati | 80.0 | Sirajganj | 50.6 |
| Jhenaidah | 65.0 | Srimangal | 50.6 |
| Khagrachhari | 56.7 | St. Martin’s Island | 80.0 |
| Khulna | 73.3 | Sunamganj | 61.1 |
| Kutubdia | 80.0 | Sylhet | 61.1 |
| Kishoreganj | 64.7 | Sandwip | 80.0 |
| Kurigram | 65.6 | Tangail | 50.6 |
| Kushtia | 66.9 | Teknaf | 80.0 |
| Lakshmipur | 51.2 | Thakurgaon | 41.4 |
| **Open Structures: Trussed Tower** | | | |
| Tower Cross Section | Cf |
| ------------------- | --------------------------- |
| Square | 4.0∈2- 5.9∈+ 4.0 |
| Triangle | 3.4∈2- 4.7∈+ 3.4 |
| Notes: | |
1. For all wind directions considered, the area Af consistent with the specified force coefficients shall be the solid area of a tower face projected on the plane of that face for the tower segment under consideration.
2. The specified force coefficients are for towers with structural angles or similar flat-sided members.
3. For towers containing rounded members, it is acceptable to multiply the specified force coefficients by the following factor when determining wind forces on such members: 0.51 ∈2 + 0.57 ≤ 1.0
4. Wind forces shall be applied in the directions resulting in maximum member forces and reactions. For towers with square cross-sections, wind forces shall be multiplied by the following factor when the wind is directed along a tower diagonal:
1 + 0.75 ∈ ≤ 1.2
5. Wind forces on tower appurtenances such as ladders, conduits, lights, elevators, etc., shall be calculated using appropriate force coefficients for these elements.
6. Notation: ∈ : ratio of solid area to gross area of one tower face for the segment under consideration.
![Force coefficient, Cf for trussed towers - Method 2 (All heights)]()
**Figure 6.2.23 Force coefficient, Cf for other structures - Method 2 (All heights)**
Table 6.2.9: Importance Factor, I (Wind Loads)
| Occupancy Category1 | Non-Cyclone Prone | Cyclone Prone Regions with |
| -------------------------------------------------------------------------------- | ------------------------- | -------------------------- |
| or | Regions and Cyclone Prone | V > 44 m/s |
| Importance Class | Regions with | |
| | V 5 38-44 m/s | |
| I | 0.87 | 0.77 |
| II | 1.0 | 1.00 |
| III | 1.15 | 1.15 |
| IV | 1.15 | 1.15 |
| 1 The building and structure classification categories are listed in Table 6.1.1 | | |
Table 6.2.10: Terrain Exposure Constants
| Exposure | $\alpha$ | $z_g$ (m) | $\hat{\alpha}$ | $\hat{b}$ | $\bar{\alpha}$ | $\bar{b}$ | c | $\ell$ (m) | $\bar{\epsilon}$ | $z_{min}$ (m)\* |
| ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------- | --------- | -------------- | --------- | -------------- | --------- | ---- | ---------- | ---------------- | --------------- |
| A | 7.0 | 365.76 | 1/7 | 0.84 | 1/4.0 | 0.45 | 0.30 | 97.54 | 1/3.0 | 9.14 |
| B | 9.5 | 274.32 | 1/9.5 | 1.00 | 1/6.5 | 0.65 | 0.20 | 152.4 | 1/5.0 | 4.57 |
| C | 11.5 | 213.36 | 1/11.5 | 1.07 | 1/9.0 | 0.80 | 0.15 | 198.12 | 1/8.0 | 2.13 |
| \*$z_{min}$ = Minimum height used to ensure that the equivalent height $z$ is greater of $0.6h$ or $z_{min}$. For buildings with $h \leq z_{min}$, $\bar{z}$ shall be taken as $z_{min}$. | | | | | | | | | | |
Table 6.2.11: Velocity Pressure Exposure Coefficients, K\_z and K\_h
| Height above | | Exposur | e(Note 1) | |
| --------------- | ------ | ------- | ---------- | ---------- |
| ground level, z | | A | B | C |
| (m) | Case 1 | Case 2 | Case 1 & 2 | Case 1 & 2 |
| 0-4.6 | 0.70 | 0.57 | 0.85 | 1.03 |
| 6.1 | 0.70 | 0.62 | 0.90 | 1.08 |
| 7.6 | 0.70 | 0.66 | 0.94 | 1.12 |
| 9.1 | 0.70 | 0.70 | 0.98 | 1.16 |
| 12.2 | 0.76 | 0.76 | 1.04 | 1.22 |
| 15.2 | 0.81 | 0.81 | 1.09 | 1.27 |
| 18 | 0.85 | 0.85 | 1.13 | 1.31 |
| 21.3 | 0.89 | 0.89 | 1.17 | 1.34 |
| 24.4 | 0.93 | 0.93 | 1.21 | 1.38 |
| 27.41 | 0.96 | 0.96 | 1.24 | 1.40 |
| 30.5 | 0.99 | 0.99 | 1.26 | 1.43 |
| 36.6 | 1.04 | 1.04 | 1.31 | 1.48 |
| 42.7 | 1.09 | 1.09 | 1.36 | 1.52 |
| 48.8 | 1.13 | 1.13 | 1.39 | 1.55 |
| 54.9 | 1.17 | 1.17 | 1.43 | 1.58 |
| 61.0 | 1.20 | 1.20 | 1.46 | 1.61 |
| 76.2 | 1.28 | 1.28 | 1.53 | 1.68 |
| 91.4 | 1.35 | 1.35 | 1.59 | 1.73 |
| 106.7 | 1.41 | 1.41 | 1.64 | 1.78 |
| 121.9 | 1.47 | 1.47 | 1.69 | 1.82 |
| 137.2 | 1.52 | 1.52 | 1.73 | 1.86 |
| 152.4 | 1.56 | 1.56 | 1.77 | 1.89 |
| Notes: | | | | |
1. Case 1:
* (a) All components and cladding.
* (b) Main wind force resisting system in low-rise buildings designed using Figure 6.2.10.
Case 2:
* (a) All main wind force resisting systems in buildings except those in lowrise buildings designed using Figure 6.2.10.
* (b) All main wind force resisting systems in other structures.
2. The velocity pressure exposure coefficient $K_z$ may be determined from the following formula:
For 4.57 m ≤ z ≤ $z_g$: $K_z = 2.01(z/z_g)^{2/\alpha}$
For z \< 4.57 m: $K_z = 2.01(4.57/z_g)^{2/\alpha}$
Note: z shall not be taken less than 9.1 m for Case 1 in exposure A.
3. $\alpha$ and $z_g$ are tabulated in Table 6.2.10.
4. Linear interpolation for intermediate values of height z is acceptable.
5. Exposure categories are defined in Sec 2.4.6.3.
Table 6.2.12: Wind Directionality Factor, $K_d$
| Structure Type | Directionality
Factor
$K_d$\* | Structure Type | Directionality
Factor
$K_d$\* |
| ---------------------------------------------------- | ---------------------------------------- | -------------------------------------------------------- | ---------------------------------------- |
| Buildings | | Solid Signs | 0.85 |
| Main Wind Force
Resisting System | 0.85 | Open Signs and Lattice
Framework | 0.85 |
| Components and
Cladding
Arched Roofs
| 0.85
0.85 | Trussed Towers
Triangular, square,
rectangular | 0.85 |
| Chimneys, Tanks, and
Similar Structures | | All other cross section | 0.95 |
| Square | 0.90 | | |
| Hexagonal | 0.95 | | |
| Round | 0.95 | | |
* Directionality Factor 0 has been calibrated with combinations of loads specified in Sec 2.7. This factor shall only be applied when used in conjunction with load combinations specified in Sections 2.7.2 and 2.7.3.
## 2.5 Earthquake Loads
### 2.5.1 General
Minimum design earthquake forces for buildings, structures or components thereof shall be determined in accordance with the provisions of Sec 2.5. Some definitions and symbols relevant for earthquake resistant design for buildings are provided in Sections 2.1.3 and 2.1.4. Section 2.5.2 presents basic earthquake resistant design concepts. Section 2.5.3 describes procedures for soil investigations, while Sec 2.5.4 describes procedures for determining earthquake ground motion for design. Section 2.5.5 describes different types of buildings and structural systems which possess different earthquake resistant characteristics. Static analysis procedures for design are described in Sections 2.5.6, 2.5.7 and 2.5.12. Dynamic analysis procedures are dealt with in Sections 2.5.8 to 2.5.11. Section 2.5.13 presents how seismic effects are accounted in the design and combination of earthquake loading effects in different directions and with other loading effects. Section 2.5.14 deals with allowable drift and deformation limits. Section 2.5.15 addresses design of non-structural components in buildings. Section 2.5.16 presents design considerations for buildings with seismic isolation systems. Design for soft storey condition in buildings is addressed in Sec 2.5.17.
### 2.5.2 Earthquake Resistant Design – Basic Concepts
#### 2.5.2.1 General principles
The purpose of earthquake resistant design provisions in this Code is to provide guidelines for the design and construction of new structures subject to earthquake ground motions in order to minimize the risk to life for all structures, to increase the expected performance of higher occupancy structures as compared to ordinary structures, and to improve the capability of essential structures to function after an earthquake. It is not economically feasible to design and construct buildings without any damage for a major earthquake event. The intent is therefore to allow inelastic deformation and structural damage at preferred locations in the structure without endangering structural integrity and to prevent structural collapse during a major earthquake.
The seismic zoning map (Fig. 6.2.24) divides the country into four seismic zones with different expected levels of intensity of ground motion. Each seismic zone has a zone coefficient which provides expected peak ground acceleration values on rock/firm soil corresponding to the maximum considered earthquake (MCE). The design basis earthquake is taken as 2/3 of the maximum considered earthquake.
The effects of the earthquake ground motion on the structure is expressed in terms of an idealized elastic design acceleration response spectrum, which depends on (a) seismic zone coefficient and local soil conditions defining ground motion and (b) importance factor and response reduction factor representing building considerations. The earthquake forces acting on the structure is reduced using the response modification/reduction factor R in order to take advantage of the inelastic energy dissipation due to inherent ductility and redundancy in the structure as well as material over-strength. The importance factor I increases design forces for important structures. The provisions of this Code for ductility and detailing need to be satisfied even for structures and members for which load combinations that do not contain the earthquake effect indicate larger demands than combinations including earthquake. The elastic deformations calculated under these reduced design forces are multiplied by the deflection amplification factor, to estimate the deformations likely to result from the design earthquake.
The seismic design guidelines presented in this Section are based on the assumption that the soil supporting the structure will not liquefy, settle or slide due to loss of strength during the earthquake. Reinforced and prestressed concrete members shall be suitably designed to ensure that premature failure due to shear or bond does not occur. Ductile detailing of reinforced concrete members is of prime importance. In steel structures, members and their connections should be so proportioned that high ductility is obtained, avoiding premature failure due to elastic or inelastic buckling of any type.
The building structure shall include complete lateral and vertical force-resisting systems capable of providing adequate strength, stiffness, and energy dissipation capacity to withstand the design ground motions within the prescribed limits of deformation and strength demand. The design ground motions shall be assumed to occur along any horizontal direction of a building structure. The adequacy of the structural systems shall be demonstrated through the construction of a mathematical model and evaluation of this model for the effects of design ground motions.
#### 2.5.2.2 Characteristics of Earthquake Resistant Buildings
The desirable characteristics of earthquake resistant buildings are described below:
Structural Simplicity, Uniformity and Symmetry:
Structural simplicity, uniformity and plan symmetry is characterized by an even distribution of mass and structural elements which allows short and direct transmission of the inertia forces created in the distributed masses of the building to its foundation. A building configuration with symmetrical layout of
structural elements of the lateral force resisting system, and well-distributed inplan, is desirable. Uniformity along the height of the building is also important, since it tends to eliminate the occurrence of sensitive zones where concentrations of stress or large ductility demands might cause premature collapse.
Some basic guidelines are given below:
* (i) With respect to the lateral stiffness and mass distribution, the building structure shall be approximately symmetrical in plan with respect to two orthogonal axes.
* (ii) Both the lateral stiffness and the mass of the individual storeys shall remain constant or reduce gradually, without abrupt changes, from the base to the top of a particular building.
* (iii)All structural elements of the lateral load resisting systems, such as cores, structural walls, or frames shall run without interruption from the foundations to the top of the building.
* (iv)An irregular building may be subdivided into dynamically independent regular units well separated against pounding of the individual units to achieve uniformity.
* (v) The length to breadth ratio (h 5 6'/6)) of the building in plan shall not be higher than 4, where 6' and 6) are respectively the larger and smaller in plan dimension of the building, measured in orthogonal directions.
**Structural Redundancy:**
A high degree of redundancy accompanied by redistribution capacity through ductility is desirable, enabling a more widely spread energy dissipation across the entire structure and an increased total dissipated energy. The use of evenly distributed structural elements increases redundancy. Structural systems of higher static indeterminacy may result in higher response reduction factor R.
**Horizontal Bi-directional Resistance and Stiffness:**
Horizontal earthquake motion is a bi-directional phenomenon and thus the building structure needs to resist horizontal action in any direction. The structural elements of lateral force resisting system should be arranged in an orthogonal (in plan) pattern, ensuring similar resistance and stiffness characteristics in both main directions. The stiffness characteristics of the structure should also limit the development of excessive displacements that might lead to either instabilities due to second order effects or excessive damages.
**Torsional Resistance and Stiffness**
Besides lateral resistance and stiffness, building structures should possess adequate torsional resistance and stiffness in order to limit the development of torsional motions which tend to stress the different structural elements in a non-uniform way. In this respect, arrangements in which the main elements resisting the seismic action are distributed close to the periphery of the building present clear advantages.
**Diaphragm Behaviour**
In buildings, floors (including the roof) act as horizontal diaphragms that collect and transmit the inertia forces to the vertical structural systems and ensure that those systems act together in resisting the horizontal seismic action. Floor systems and the roof should be provided with in-plane stiffness and resistance and with effective connection to the vertical structural systems. Particular care should be taken in cases of non-compact or very elongated in-plan shapes and in cases of large floor openings, especially if the latter are located in the vicinity of the main vertical structural elements, thus hindering such effective connection between the vertical and horizontal structure. The in-plane stiffness of the floors shall be sufficiently large in comparison with the lateral stiffness of the vertical structural elements, so that the deformation of the floor shall have a small effect on the distribution of the forces among the vertical structural elements.
**Foundation**
The design and construction of the foundation and of its connection to the superstructure shall ensure that the whole building is subjected to a uniform seismic excitation. For buildings with individual foundation elements (footings or piles), the use of a foundation slab or tie-beams between these elements in both main directions is recommended, as described in Chapter 3.
### 2.5.3 Investigation and Assessment of Site Conditions
#### 2.5.3.1 Site investigation
Appropriate site investigations should be carried out to identify the ground conditions influencing the seismic action.
The ground conditions at the building site should normally be free from risks of ground rupture, slope instability and permanent settlements caused by liquefaction or densification during an earthquake. The possibility of such phenomena should be investigated in accordance with standard procedures described in Chapter 3 of this Part.
The intent of the site investigation is to classify the Site into one of types SA, SB, SC, SD, SE, S1 and S2 as defined in Sec 2.5.3.2. Such classification is based on site profile and evaluated soil properties (shear wave velocity, Standard Penetration Resistance, undrained shear strength, soil type). The site class is used to determine the effect of local soil conditions on the earthquake ground motion.
For sites representing special soil type S1 or S2, site specific special studies for the ground motion should be done. Soil type S1, having very low shear wave velocity and low material damping, can produce anomalous seismic site amplification and soil-structure interaction effects. For S2 soils, possibility of soil failure should be studied.
For a structure belonging to Seismic Design Category C or D (Sec 2.5.5.2), site investigation should also include determination of soil parameters for the assessment of the following:
* (a) Slope instability.
* (b) Potential for Liquefaction and loss of soil strength.
* (c) Differential settlement.
* (d) Surface displacement due to faulting or lateral spreading.
* (e) Lateral pressures on basement walls and retaining walls due to earthquake ground motion.
Liquefaction potential and possible consequences should be evaluated for design earthquake ground motions consistent with peak ground accelerations. Any Settlement due to densification of loose granular soils under design earthquake motion should be studied. The occurrence and consequences of geologic hazards such as slope instability or surface faulting should also be considered. The dynamic lateral earth pressure on basement walls and retaining walls during earthquake ground shaking is to be considered as an earthquake load for use in design load combinations
#### 2.5.3.2 Site classification
Site will be classified as type SA, SB, SC, SD, SE, S1 and S2 based on the provisions of this Section. Classification will be done in accordance with Table 6.2.13 based on the soil properties of upper 30 meters of the site profile. Average soil properties will be determined as given in the following equations:
Where,
* 5 Number of soil layers in upper 30 m
* 5 Thickness of layer
* 5 Shear wave velocity of layer
* : 5 Field (uncorrected) Standard Penetration Value for layer
m 5 Number of cohesive soil layers in upper 30 m
* * 5 Thickness of cohesive layer
* ZD 5 Undrained shear strength of cohesive layer
The site profile up to a depth of 30 m is divided into n number of distinct soil or rock layers. Where some of the layers are cohesive, m is the number of cohesive layers. Hence ∑)1 5 30 m, while ∑l1 + \< 30 m if m \< \* in other words if there are both cohesionless and cohesive layers. The standard penetration value N as directly measured in the field without correction will be used.
The site classification should be done using average shear wave velocity F if this can be estimated, otherwise the value of :\_ may be used.
Table 6.2.13: Site Classification Based on Soil Properties
| Site | Description of soil | Average Soil | Properties in top | 30 meters |
| ----- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------- | ----------------------------------------- | ------------------------------------------------ |
| Class | profile up to 30
meters depth | Shear wave
velocity,\_ (m/s) | SPT Value,\_
(blows/30cm) | Undrained shear
strength,\_(kPa) |
| SA | Rock or other rock-like
geological formation,
including at most 5 m of
weaker material at the
surface. | > 800 | -- | -- |
| SB | Deposits of very dense
sand, gravel, or very stiff
clay, at least several tens
of metres in thickness,
characterised by a
gradual increase of
mechanical properties
with depth. | 360 – 800 | > 50 | > 250 |
| Class |
profile up to 30
meters depth | Shear wave
velocity,\_ (m/s) | SPT Value,\_
(blows/30cm) | Undrained shear
strength,\_(kPa) |
| SC | Deep deposits of dense
or medium dense sand,
gravel or stiff clay with
thickness from several
tens to many hundreds
of metres. | 180 – 360 | 15 - 50 | 70 - 250 |
| SD | Deposits of loose-to-
medium cohesionless
soil (with or without
some soft cohesive
layers), or of
predominantly soft-to-
firm cohesive soil. | \< 180 | \< 15 | \< 70 |
| SE | A soil profile consisting
of a surface alluvium
layer with Vsvalues of
type SC or SD and
thickness varying
between about 5 m and
20 m, underlain by
stiffer material with Vs>
800 m/s. | -- | -- | -- |
| S1 | Deposits consisting, or
containing a layer at
least 10 m thick, of soft
clays/silts with a high
plasticity index (PI >
40) and high water
content | \< 100
(indicative) | -- | 10 - 20 |
| S2 | Deposits of liquefiable
soils, of sensitive clays,
or any other soil profile
not included in types SA
to SE or S1 | -- | -- | -- |
### 2.5.4 Earthquake Ground Motion
#### 2.5.4.1 Regional seismicity
Bangladesh can be affected by moderate to strong earthquake events due to its proximity to the collision boundary of the Northeast moving Indian plate and Eurasian Plate. Strong historical earthquakes with magnitude greater than 7.0 have affected parts of Bangladesh in the last 150 years, some of them had their epicenters within the country. A brief description of the local geology, tectonic features and earthquake occurrence in the region is given in Appendix B.
#### 2.5.4.2 Seismic zoning
The intent of the seismic zoning map is to give an indication of the Maximum Considered Earthquake (MCE) motion at different parts of the country. In probabilistic terms, the MCE motion may be considered to correspond to having a 2% probability of exceedance within a period of 50 years. The country has been divided into four seismic zones with different levels of ground motion. Table 6.2.14 includes a description of the four seismic zones. Figure 6.2.24 presents a map of Bangladesh showing the boundaries of the four zones. Each zone has a seismic zone coefficient (Z) which represents the maximum considered peak ground acceleration (PGA) on very stiff soil/rock (site class SA) in units of g (acceleration due to gravity). The zone coefficients (Z) of the four zones are: Z50.12 (Zone 1), Z50.20 (Zone 2), Z50.28 (Zone 3) and Z50.36 (Zone 4). Table 6.2.15 lists zone coefficients for some important towns of Bangladesh. The most severe earthquake prone zone, Zone 4 is in the northeast which includes Sylhet and has a maximum PGA value of 0.36g. Dhaka city falls in the moderate seismic intensity zone with Z50.2, while Chittagong city falls in a severe intensity zone with Z50.28.
#### 2.5.4.3 Design response spectrum
The earthquake ground motion for which the building has to be designed is represented by the design response spectrum. Both static and dynamic analysis methods are based on this response spectrum. This spectrum represents the spectral acceleration for which the building has to be designed as a function of the building period, taking into account the ground motion intensity. The spectrum is based on elastic analysis but in order to account for energy dissipation due to inelastic deformation and benefits of structural redundancy, the spectral accelerations are reduced by the response modification factor R. For important structures, the spectral accelerations are increased by the importance factor I. The design basis earthquake (DBE) ground motion is
selected at a ground shaking level that is 2/3 of the maximum considered earthquake (MCE) ground motion. The effect of local soil conditions on the response spectrum is incorporated in the normalized acceleration response spectrum Cs. The spectral acceleration for the design earthquake is given by the following equation:
$$
S_a = \frac{2}{3}\frac{ZI}{R}C_s \tag{6.2.34}
$$
Where,
* $S_a =$ Design spectral acceleration (in units of $g$) which shall not be less than $0.67\beta ZIS$
* $\beta =$ Coefficient used to calculate lower bound for $S_a$. Recommended value for $\beta$ is 0.11
* $Z =$ Seismic zone coefficient, as defined in Sec 2.5.4.2
* $I =$ Structure importance factor, as defined in Sec 2.5.5.1
* $R =$ Response reduction factor which depends on the type of structural system given in Table 6.2.19. The ratio $\frac{I}{R}$ cannot be greater than one.
* $C_s =$ Normalized acceleration response spectrum, which is a function of structure (building) period and soil type (site class) as defined by Equations 6.2.35a to 6.2.35d.
$$
C_s = S\left(1+\frac{T}{T_B}(2.5\eta-1)\right) \text{ for } 0 \leq T \leq T_B \tag{6.2.35a}
$$
$$
C_s = 2.5S\eta \text{ for } T_B \leq T \leq T_C \tag{6.2.35b}
$$
$$
C_s = 2.5S\eta\left(\frac{T_C}{T}\right) \text{ for } T_C \leq T \leq T_D \tag{6.2.35c}
$$
$$
C_s = 2.5S\eta\left(\frac{T_CT_D}{T^2}\right) \text{ for } T_D \leq T \leq 4 \text{ sec} \tag{6.2.35d}
$$
$C_s$ depends on S and values of TB, TC and TD, (Figure 6.2.25) which are all functions of the site class. Constant Cs value between periods TB and TC represents constant spectral acceleration.
* S 5 Soil factor which depends on site class and is given in Table 6.2.16
* T 5 Structure (building) period as defined in Sec 2.5.7.2
* TB 5 Lower limit of the period of the constant spectral acceleration branch given in Table 6.2.16 as a function of site class.
* TC 5 Upper limit of the period of the constant spectral acceleration branch given in Table 6.2.16 as a function of site class
* TD 5 Lower limit of the period of the constant spectral displacement branch given in Table 6.2.16 as a function of site class
* $\eta$ = Damping correction factor as a function of damping with a reference value of $\eta = 1$ for 5% viscous damping. It is given by the following expression:
$$
\eta = \sqrt{10/(5 + \xi)} \geq 0.55 \tag{6.2.36}
$$
Where, $\xi$ is the viscous damping ratio of the structure, expressed as a percentage of critical damping. The value of $\eta$ cannot be smaller than 0.55.
The anticipated (design basis earthquake) peak ground acceleration (PGA) for rock or very stiff soil (site class SA) is $\frac{2}{3}Z$. However, for design, the ground motion is modified through the use of response reduction factor R and importance factor I, resulting in $PGA_{rock} = \frac{2}{3}\left(\frac{ZI}{R}\right)$. Figure 6.2.26 shows the normalized acceleration response spectrum Cs for 5% damping, which may be defined as the 5% damped spectral acceleration (obtained by Eq. 6.2.34) normalized with respect to $PGA_{rock}$. This Figure demonstrates the significant influence of site class on the response spectrum.
**Design Spectrum for Elastic Analysis**
For site classes SA to SE, the design acceleration response spectrum for elastic analysis methods is obtained using Eq. 6.2.34 to compute Sa (in units of g) as a function of period T. The design acceleration response spectrum represents the expected ground motion (Design Basis Earthquake) divided by the factor R/I.
**Design Spectrum for Inelastic Analysis**
For inelastic analysis methods, the anticipated ground motion (Design Basis Earthquake) is directly used. Corresponding real design acceleration response spectrum is used, which is obtained by using R51 and I51 in Eq. 6.2.34. The ‘real design acceleration response spectrum’ is equal to ‘design acceleration response spectrum’ multiplied by R/I.
**Site-Specific Design Spectrum**
For site class S1 and S2, site-specific studies are needed to obtain design response spectrum. For important projects, site-specific studies may also be carried out to determine spectrum instead of using Eq. 6.2.34. The objective of such site-specific ground-motion analysis is to determine ground motions for local seismic and site conditions with higher confidence than is possible using simplified equations.
![Seismic zoning map of Bangladesh]()
Figure 6.2.24 Seismic zoning map of Bangladesh
Table 6.2.14: Description of Seismic Zones
| Seismic
Zone | Location | Seismic
Intensity | Seismic Zone
Coefficient,Z |
| --------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------- | -------------------------------- |
| 1 | Southwestern part including Barisal, Khulna,
Jessore, Rajshahi | Low | 0.12 |
| 2 | Lower Central and Northwestern part including
Noakhali, Dhaka, Pabna, Dinajpur, as well as
Southwestern corner including Sundarbans | Moderate | 0.20 |
| 3 | Upper Central and Northwestern part including
Brahmanbaria, Sirajganj, Rangpur | Severe | 0.28 |
| 4 | Northeastern part including Sylhet,
Mymensingh, Kurigram | Very Severe | 0.36 |
| Table 6.2.15: Seismic Zone Coefficient Z for Some Important Towns of Bangladesh | | | |
| Town | Z | Town | Z | Town | Z | Town | Z |
| --------------- | ---- | ----------- | ---- | ----------- | ---- | ---------- | ---- |
| Bagerhat | 0.12 | Gaibandha | 0.28 | Magura | 0.12 | Patuakhali | 0.12 |
| Bandarban | 0.28 | Gazipur | 0.20 | Manikganj | 0.20 | Pirojpur | 0.12 |
| Barguna | 0.12 | Gopalganj | 0.12 | Maulvibazar | 0.36 | Rajbari | 0.20 |
| Barisal | 0.12 | Habiganj | 0.36 | Meherpur | 0.12 | Rajshahi | 0.12 |
| Bhola | 0.12 | Jaipurhat | 0.20 | Mongla | 0.12 | Rangamati | 0.28 |
| Bogra | 0.28 | Jamalpur | 0.36 | Munshiganj | 0.20 | Rangpur | 0.28 |
| Brahmanbaria | 0.28 | Jessore | 0.12 | Mymensingh | 0.36 | Satkhira | 0.12 |
| Chandpur | 0.20 | Jhalokati | 0.12 | Narail | 0.12 | Shariatpur | 0.20 |
| Chapainababganj | 0.12 | Jhenaidah | 0.12 | Narayanganj | 0.20 | Sherpur | 0.36 |
| Chittagong | 0.28 | Khagrachari | 0.28 | Narsingdi | 0.28 | Sirajganj | 0.28 |
| Chuadanga | 0.12 | Khulna | 0.12 | Natore | 0.20 | Srimangal | 0.36 |
| Comilla | 0.20 | Kishoreganj | 0.36 | Naogaon | 0.20 | Sunamganj | 0.36 |
| Cox's Bazar | 0.28 | Kurigram | 0.36 | Netrakona | 0.36 | Sylhet | 0.36 |
| Dhaka | 0.20 | Kushtia | 0.20 | Nilphamari | 0.12 | Tangail | 0.28 |
| Dinajpur | 0.20 | Lakshmipur | 0.20 | Noakhali | 0.20 | Thakurgaon | 0.20 |
| Faridpur | 0.20 | Lalmanirhat | 0.28 | Pabna | 0.20 | | |
| Feni | 0.20 | Madaripur | 0.20 | Panchagarh | 0.20 | | |
![Typical shape of the elastic response spectrum coefficient Cs]()
Figure 6.2.25 Typical shape of the elastic response spectrum coefficient Cs
Table 6.2.16: Site Dependent Soil Factor and Other Parameters Defining Elastic Response Spectrum
| Soil type | S | TB(s) | TC (s) | TD (s) |
| --------- | ---- | ----- | ------ | ------ |
| SA | 1.0 | 0.15 | 0.40 | 2.0 |
| SB | 1.2 | 0.15 | 0.50 | 2.0 |
| SC | 1.15 | 0.20 | 0.60 | 2.0 |
| SD | 1.35 | 0.20 | 0.80 | 2.0 |
| SE | 1.4 | 0.15 | 0.50 | 2.0 |
![Normalized design acceleration response spectrum for different site classes]()
Figure 6.2.26 Normalized design acceleration response spectrum for different site classes.
### 2.5.5 Building Categories
#### 2.5.5.1 Importance factor
Buildings are classified in four occupancy categories in Chapter 1 (Table 6.1.1), depending on the consequences of collapse for human life, on their importance for public safety and civil protection in the immediate post-earthquake period, and on the social and economic consequences of collapse. Depending on occupancy category, buildings may be designed for higher seismic forces using importance factor greater than one. Table 6.2.17 defines different occupancy categories and corresponding importance factor.
Table 6.2.17: Importance Factors for Buildings and Structures for Earthquake design
| OccupancyCategory | Importance factor I |
| ----------------- | ------------------- |
| I, II | 1.00 |
| III | 1.25 |
| IV | 1.50 |
#### 2.5.5.2 Seismic design category
Buildings shall be assigned a seismic design category among B, C or D based on seismic zone, local site conditions and importance class of building, as given in Table 6.2.18. Seismic design category D has the most stringent seismic design detailing, while seismic design category B has the least seismic design detailing requirements.
Table 6.2.18: Seismic Design Category of Buildings
| Site
Class | Occupa
Zone 1 | ncyCate
Zone 2 | goryI, II
Zone 3 | and III
Zone 4 | Oc
Zone 1 | cupancy
Zone 2 | Category
Zone 3 | IV
Zone 4 |
| --------------- | ------------------ | ------------------- | --------------------- | ------------------- | -------------- | -------------------- | -------------------- | -------------- |
| SA | B | C | C | D | C | D | D | D |
| SB | B | C | D | D | C | D | D | D |
| SC | B | C | D | D | C | D | D | D |
| SD | C | D | D | D | D | D | D | D |
| SE, S1, S2 | D | D | D | D | D | D | D | D |
#### 2.5.5.3 Building irregularity
Buildings with irregularity in plan or elevation suffer much more damage in earthquakes than buildings with regular configuration. A building may be considered as irregular, if at least one of the conditions given below are applicable:
##### 2.5.5.3.1
Plan irregularity: Following are the different types of irregularities that may exist in the plan of a building.
* (i) Torsion irregularity
To be considered for rigid floor diaphragms, when the maximum storey drift ($\Delta_{max}$) as shown in Figure 6.2.27(a), computed including accidental torsion, at one end of the structure is more than 1.2 times the average $\left(\Delta_{avg} = \dfrac{\Delta_{max} + \Delta_{min}}{2}\right)$ of the storey drifts at the two ends of the structure. If $\Delta_{max} > 1.4\Delta_{avg}$ then the irregularity is termed as extreme torsional irregularity.
* (ii) Re-entrant corners
Both projections of the structure beyond a re-entrant comer \[Figure 6.2.27(b)] are greater than 15 percent of its plan dimension in the given direction.
* (iii) Diaphragm Discontinuity
Diaphragms with abrupt discontinuities or variations in stiffness, including those having cut-out \[Figure 6.2.27(c)] or open areas greater than 50 percent of the gross enclosed diaphragm area, or changes in effective diaphragm stiffness of more than 50 percent from one storey to the next.
* (iv) Out- of-Plane Offsets
Discontinuities in a lateral force resistance path, such as out-of-plane offsets of vertical elements, as shown in Figure 6.2.27(d).
* (v) Non-parallel Systems
The vertical elements resisting the lateral force are not parallel to or symmetric \[Figure 6.2.27(e)] about the major orthogonal axes of the lateral force resisting elements.
##### 2.5.5.3.2
Vertical Irregularity: Following are different types of irregularities that may exist along vertical elevations of a building.
* (i) Stiffness Irregularity - Soft Storey
A soft storey is one in which the lateral stiffness is less than 70% of that in the storey above or less than 80% of the average lateral stiffness of the three storeys above irregularity \[Figure 6.2.28(a)]. An extreme soft storey is defined where its lateral stiffness is less than 60% of that in the storey above or less than 70% of the average lateral stiffness of the three storeys above.
* (ii) Mass Irregularity
The seismic weight of any storey is more than twice of that of its adjacent storeys \[Figure 6.2.28(b)]. This irregularity need not be considered in case of roofs.
* (iii) Vertical Geometric Irregularity
* This irregularity exists for buildings with setbacks with dimensions given in Figure \[6.2.28(c)].
* (iv) Vertical In-Plane Discontinuity in Vertical Elements Resisting Lateral Force
An in-plane offset of the lateral force resisting elements greater than the length of those elements \[Figure 6.2.28(d)].
* (v) Discontinuity in Capacity - Weak Storey
A weak storey is one in which the storey lateral strength is less than 80% of that in the storey above. The storey lateral strength is the total strength of all seismic force resisting elements sharing the storey shear in the considered direction \[Figure 6.2.28(e)]. An extreme weak storey is one where the storey lateral strength is less than 65% of that in the storey above.
#### 2.5.5.4 Type of structural systems
The basic lateral and vertical seismic force–resisting system shall conform to one of the types A to G indicated in Table 6.2.19. Each type is again subdivided by the types of vertical elements used to resist lateral seismic forces. A combination of systems may also be permitted as stated in Sec 2.5.5.5.
The structural system to be used shall be in accordance with the seismic design category indicated in Table 6.2.18. Structural systems that are not permitted for a certain seismic design category are indicated by “NP”. Structural systems that do not have any height restriction are indicated by “NL”. Where there is height limit, the maximum height in meters is given.
The response reduction factor, R, and the deflection amplification factor, indicated in Table 6.2.19 shall be used in determining the design base shear and design story drift. The selected seismic force-resisting system shall be designed and detailed in accordance with the specific requirements for the system.
Seismic force resisting systems that are not given in Table 6.2.19 may be permitted if substantial analytical and test data are submitted that establish the dynamic characteristics and demonstrate the lateral force resistance and energy dissipation capacity to be equivalent to the structural systems listed in Table 6.2.19 for equivalent response modification coefficient, R, and deflection amplification factor, values.
![Different types of plan irregularities of buildings: (a) Torsional Irregularity, (b) Re-entrant corners, (c) Diaphragm discontinuity, (d) Out-of-plane offsets of shear wall, (e) Non-parallel systems of shear wall]()
(a) Torsional Irregularity
(b) Re-entrant corners (A/L>0.15)
(c) Diaphragm discontinuity
(d) Out- of-plane offsets of shear wall
(e) Non-parallel systems of shear wall
Figure 6.2.27 Different types of plan irregularities of buildings
![Different types of vertical irregularities of buildings: (a) Soft storey, (b) Mass irregularity, (c) Vertical geometric irregularity, (d) Vertical In-Plane Discontinuity, (e) Weak storey]()
(a) Soft storey
(b) Mass irregularity
(c) Vertical geometric irregularity (setback structures )
* (d) Vertical In-Plane Discontinuity in Vertical (e) Weak storey Elements Resisting Lateral Force
Figure 6.2.28 Different types of vertical irregularities of buildings
Table 6.2.19: Response Reduction Factor, Deflection Amplification Factor and Height Limitations for Different Structural Systems
| **Seismic Force–Resisting System**
A. BEARING WALL SYSTEMS
(no frame) | **Response**
**Reduction**
**Factor,\*\*\*\**R*** | **System**
**Overstrength**
\*\*Factor,\*\*Ω | **Deflection**
**Amplification**
**Factor,**" | **Seismic**
**Design**
**Category**
**B**
**He** | **Seismic**
**Design**
**Category**
**C**
**ight limit** |
**Seismic**
**Design**
**Category**
**D**
**(m)** |
| --------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------- | ------------------------------------------------------ | ------------------------------------------------------- | -------------------------------------------------------------------- | ---------------------------------------------------------------------------- | --------------------------------------------------------------------------- |
| 1. Special reinforced
concrete shear walls | 5 | 2.5 | 5 | NL | NL | 50 |
| 2. Ordinary reinforced
concrete shear walls | 4 | 2.5 | 4 | NL | NL | NP |
| 3. Ordinary reinforced
masonry shear walls | 2 | 2.5 | 1.75 | NL | 50 | NP |
| 4. Ordinary plain masonry
shear walls | 1.5 | 2.5 | 1.25 | 18 | NP | NP |
| **Seismic Force–Resisting System** | **Response**
**Reduction**
**Factor,\*\*\*\**R*** | **System**
**Overstrength**
\*\*Factor,\*\*Ω | **Deflection**
**Amplification**
**Factor,**" | **Seismic**
**Design**
**Category**
**B** | **Seismic**
**Design**
**Category**
**C** |
**Seismic**
**Design**
**Category**
**D** |
| | | | | **He** | **ight limit** | **(m)** |
| B. BUILDING FRAME SYSTEMS
(with bracingor shear wall) | | | | | | |
| 1. Steel eccentrically braced
frames, moment resisting
connections at columns
away from links | 8 | 2 | 4 | NL | NL | 50 |
| 2. Steel eccentrically braced
frames, non-moment-
resisting, connections at
columns away from links | 7 | 2 | 4 | NL | NL | 50 |
| 3. Special steel concentrically
braced frames | 6 | 2 | 5 | NL | NL | 50 |
| 4. Ordinary steel
concentrically braced
frames | 3.25 | 2 | 3.25 | NL | NL | 11 |
| 5. Special reinforced concrete
shear walls | 6 | 2.5 | 5 | NL | NL | 50 |
| 6. Ordinary reinforced
concrete shear walls | 5 | 2.5 | 4.25 | NL | NL | NP |
| 7. Ordinary reinforced
masonry shear walls | 2 | 2.5 | 2 | NL | 50 | NP |
| 8. Ordinary plain masonry
shear walls | 1.5 | 2.5 | 1.25 | 18 | NP | NP |
| C. MOMENT RESISTING
FRAME SYSTEMS (no
shear wall) | | | | | | |
| 1. Special steel moment
frames | 8 | 3 | 5.5 | NL | NL | NL |
| 2. Intermediate steel moment
frames | 4.5 | 3 | 4 | NL | NL | 35 |
| 3. Ordinary steel moment
frames | 3.5 | 3 | 3 | NL | NL | NP |
| **Seismic Force–Resisting System** | **Response**
**Reduction**
**Factor,\*\*\*\**R*** | **System**
**Overstrength**
\*\*Factor,\*\*Ω | **Deflection**
**Amplification**
**Factor,**" | **Seismic**
**Design**
**Category**
**B**
**He** | **Seismic**
**Design**
**Category**
**C**
**ight limit** |
**Seismic**
**Design**
**Category**
**D**
**(m)** |
| 4. Special reinforced concrete
moment frames | 8 | 3 | 5.5 | NL | NL | NL |
| 5. Intermediate reinforced
concrete moment frames | 5 | 3 | 4.5 | NL | NL | NP |
| 5. Ordinary reinforced
concrete moment frames | 3 | 3 | 2.5 | NL | NP | NP |
| D. DUAL SYSTEMS: SPECIAL
MOMENT FRAMES
CAPABLE OF RESISTING AT
LEAST 25% OF
PRESCRIBED SEISMIC
FORCES
(with bracing or shear wall) | | | | | | |
| 1. Steel eccentrically braced
frames | 8 | 2.5 | 4 | NL | NL | NL |
| 2. Special steel concentrically
braced frames | 7 | 2.5 | 5.5 | NL | NL | NL |
| 3. Special reinforced concrete
shear walls | 7 | 2.5 | 5.5 | NL | NL | NL |
| 4. Ordinary reinforced
concrete shear walls | 6 | 2.5 | 5 | NL | NL | NP |
| E. DUAL SYSTEMS:
INTERMEDIATE MOMENT
FRAMES CAPABLE OF
RESISTING AT LEAST 25%
OF PRESCRIBED SEISMIC
FORCES
(with bracing or shear wall) | | | | | | |
| 1. Special steel concentrically
bracedframes | 6 | 2.5 | 5 | NL | NL | 11 |
| 2. Special reinforced concrete
shear walls | 6.5 | 2.5 | 5 | NL | NL | 50 |
| 3. Ordinary reinforced
masonry shear walls | 3 | 3 | 3 | NL | 50 | NP |
| 4. Ordinary reinforced
concrete shear walls | 5.5 | 2.5 | 4.5 | NL | NL | NP |
| F. DUAL SHEAR WALL-
FRAME SYSTEM:
ORDINARY REINFORCED
CONCRETE MOMENT
FRAMES AND ORDINARY
REINFORCED CONCRETE
SHEAR WALLS | 4.5 | 2.5 | 4 | NL | NP | NP |
| G. STEEL SYSTEMS NOT
SPECIFICALLY
DETAILED FOR SEISMIC
RESISTANCE | 3 | 3 | 3 | NL | NL | NP |
| Notes: | | | | | | |
1. Seismic design category, NL 5 No height restriction, NP 5 Not permitted. Number represents maximum allowable height (m).
2. Dual Systems include buildings which consist of both moment resisting frame and shear walls (or braced frame) where both systems resist the total design forces in proportion to their lateral stiffness.
3. See Sec. 10.20 of Chapter 10 of this Part for additional values of R and " and height limits for some other types of steel structures not covered in this Table.
4. Where data specific to a structure type is not available in this Table, reference may be made to Table 12.2-1 of ASCE 7-05.
#### 2.5.5.5 Combination of structural systems
##### 2.5.5.5.1
Combinations of Structural Systems in Different Directions: Different seismic force–resisting systems are permitted to be used to resist seismic forces along each of the two orthogonal axes of the structure. Where different systems are used, the respective R and coefficients shall apply to each system, including the limitations on system use contained in Table 6.2.19.
##### 2.5.5.5.2
Combinations of Structural Systems in the Same Direction: Where different seismic force–resisting systems are used in combination to resist seismic forces in the same direction of structural response, other than those combinations considered as dual systems, the more stringent system limitation contained in Table 6.2.19 shall apply. The value of R used for design in that direction shall not be greater than the least value of R for any of the systems utilized in that direction. The deflection amplification factor, in the direction under consideration at any story shall not be less than the largest value of this factor for the R factor used in the same direction being considered.
#### 2.5.5.6 Provisions for Using System Overstrength Factor, Ω
##### 2.5.5.6.1 Combinations of Elements Supporting Discontinuous Walls or Frames.
Columns, beams, trusses, or slabs supporting discontinuous walls or frames of structures having horizontal irregularity Type IV of Table 6.1.5 or vertical irregularity Type IV of Table 6.1.4 shall have the design strength to resist the maximum axial force that can develop in accordance with the load combinations with overstrength factor of Section 2.5.13.4. The connections of such discontinuous elements to the supporting members shall be adequate to transmit the forces for which the discontinuous elements were required to be designed.
##### 2.5.5.6.2 Increase in Forces Due to Irregularities for Seismic Design Category D.
For structures assigned to Seismic Design Category D and having a horizontal structural irregularity of Type I.a, I.b, II, III, or IV in Table 6.1.5 or a vertical structural irregularity of Type IV in Table 6.1.4, the design forces determined from Section 2.5.7 shall be increased 25 percent for connections of diaphragms to vertical elements and to collectors and for connections of collectors to the vertical elements. Collectors and their connections also shall be designed for these increased forces unless they are designed for the load combinations with overstrength factor of Section 2.5.5.4, in accordance with Section 2.5.13.4.
##### 2.5.5.6.3 Collector Elements Requiring Load Combinations with Overstrength Factor for Seismic Design Categories C through D.
In structures assigned to Seismic Design Category C or D, collector elements, splices, and their connections to resisting elements shall resist the load combinations with overstrength of Section 2.5.13.4.
##### 2.5.5.6.4 Batter Piles.
Batter piles and their connections shall be capable of resisting forces and moments from the load combinations with overstrength factor of Section 2.5.13.4. Where vertical and batter piles act jointly to resist foundation forces as a group, these forces shall be distributed to the individual piles in accordance with their relative horizontal and vertical rigidities and the geometric distribution of the piles within the group.
### 2.5.6 Static Analysis Procedure
Although analysis of buildings subjected to dynamic earthquake loads should theoretically require dynamic analysis procedures, for certain type of building structures subjected to earthquake shaking, simplified static analysis procedures may also provide reasonably good results. The equivalent static force method is such a procedure for determining the seismic lateral forces acting on the structure. This type of analysis may be applied to buildings whose seismic response is not significantly affected by contributions from modes higher than the fundamental mode in each direction. This requirement is deemed to be satisfied in buildings which fulfill the following two conditions:
* (a) The building period in the two main horizontal directions is smaller than both 4TC (TC is defined in Sec 2.5.4.3) and 2 seconds.
* (b) The building does not possess irregularity in elevation as defined in Sec 2.5.5.3.
### 2.5.7 Equivalent Static Analysis
The evaluation of the seismic loads starts with the calculation of the design base shear which is derived from the design response spectrum presented in Sec 2.5.4.3. This Section presents different computations relevant to the equivalent static analysis procedure.
#### 2.5.7.1 Design base shear
The seismic design base shear force in a given direction shall be determined from the following relation:
$$
V = S_aW \tag{6.2.37}
$$
Where,
* $S_a =$ Lateral seismic force coefficient calculated using Eq. 6.2.34 (Sec 2.5.4.3). It is the design spectral acceleration (in units of g) corresponding to the building period $T$ (computed as per Sec 2.5.7.2).
* $W =$ Total seismic weight of the building defined in Sec 2.5.7.3
Alternatively, for buildings with natural period less than or equal to 2.0 sec., the seismic design base shear can be calculated using ASCE 7-02 with seismic design parameters as given in Appendix C. However, the minimum value of $S_a$ should not be less than 0.044 $S_{DS}I$. The values of $S_{DS}$ are provided in Table 6.C.4 of Appendix C.
#### 2.5.7.2 Building period
The fundamental period T of the building in the horizontal direction under consideration shall be determined using the following guidelines:
* (a) Structural dynamics procedures (such as Rayleigh method or modal eigenvalue analysis), using structural properties and deformation characteristics of resisting elements, may be used to determine the fundamental period T of the building in the direction under consideration. This period shall not exceed the approximate fundamental period determined by Eq. 6.2.38 by more than 40 percent.
* (b) The building period T (in sec) may be approximated by the following formula:
$$
T = C_t(h_n)^m \tag{6.2.38}
$$
Where,
* $h_n =$ Height of building in metres from foundation or from top of rigid basement. This excludes the basement storeys, where basement walls are connected with the ground floor deck or fitted between the building columns. But it includes the basement storeys, when they are not so connected. $C_t$ and $m$ are obtained from Table 6.2.20
* (c) For masonry or concrete shear wall structures, the approximate fundamental period, T (in sec) may be determined as follows:
$$
T = \frac{0.0062}{\sqrt{C_w}}h_n \tag{6.2.39}
$$
$$
C_w = \frac{100}{A_B}\sum_{i=1}^{x}\left(\frac{h_n}{h_i}\right)^2\frac{A_i}{\left[1+0.83\left(\frac{h_i}{D_i}\right)^2\right]} \tag{6.2.40}
$$
Where,
* *AB* = area of base of structure *hi* = height of shear wall “i”
* *Ai* = web area of shear wall “i” *Di* = length of shear wall “i”
* *x* = number of shear walls in the building effective in resisting lateral forces in the direction under consideration.
Table 6.2.20: Values for Coefficients to Estimate Approximate Period
| Structure type | Ct | m | | | | |
| -------------------------------- | ------ | ---- | ---------------------------------- | ----------------------------- | -------------------------------------- | ------------- |
| Concrete moment-resisting frames | 0.0466 | 0.9 | Note:
resisting | Consid
fram | er
mo
es as fra | ment
mes |
| Steel moment-resisting frames | 0.0724 | 0.8 | which
seismic | resist
force | 100%
and are | of
not |
| Eccentrically braced steel frame | 0.0731 | 0.75 | enclosed
compone | or
nts th | adjoined
at are m | by
ore |
| All other structural systems | 0.0488 | 0.75 | rigid an
frames
under se | d will
from
ismic f | prevent
deflec
orces. | the
ting |
#### 2.5.7.3 Seismic weight
Seismic weight, W, is the total dead load of a building or a structure, including partition walls, and applicable portions of other imposed loads listed below:
* (a) For live load up to and including 3 kN/m2 , a minimum of 25 percent of the live load shall be applicable.
* (b) For live load above 3 kN/m2 , a minimum of 50 percent of the live load shall be applicable.
* (c) Total weight (100 percent) of permanent heavy equipment or retained liquid or any imposed load sustained in nature shall be included.
Where the probable imposed loads (mass) at the time of earthquake are more correctly assessed, the designer may go for higher percentage of live load.
#### 2.5.7.4 Vertical distribution of lateral forces
In the absence of a more rigorous procedure, the total seismic lateral force at the base level, in other words the base shear V, shall be considered as the sum of lateral forces $F_x$ induced at different floor levels, these forces may be calculated as:
$$
F_x = V\frac{w_xh_x^k}{\sum_{i=1}^{n}w_ih_i^k} \tag{6.2.41}
$$
Where,
$F_x =$ Part of base shear force induced at level x
$w_i$ and $w_x =$ Part of the total effective seismic weight of the structure
(W) assigned to level i or x
$h_i$ and $h_x =$ the height from the base to level i or x
$k = 1$ For structure period ≤ 0.5s
$= 2$ for structure period ≥ 2.5s
$=$ linear interpolation between 1 and 2 for other periods.
n 5 number of stories
#### 2.5.7.5 Storey shear and its horizontal distribution
The design storey shear $V_x$, at any storey $x$ is the sum of the forces $F_x$ in that storey and all other stories above it, given by Eq. 6.2.42:
$$
V_x = \sum_{i=x}^{n}F_i \tag{6.2.42}
$$
Where, $F_i =$ Portion of base shear induced at level i, as determined by Eq. 6.2.41.
If the floor diaphragms can be considered to be infinitely rigid in the horizontal plane, the shear shall be distributed to the various elements of the lateral force resisting system in proportion to their relative lateral stiffness. For flexible diaphragms, the distribution of forces to the vertical elements shall account for the position and distribution of the masses supported.
Allowance shall also be made for the increased shear arising due to horizontal torsional moment as specified in Sec 2.5.7.6
#### 2.5.7.6 Horizontal torsional moments
Design shall accommodate increase in storey shear forces resulting from probable horizontal torsional moments on rigid floor diaphragms. Computation of such moments shall be as follows:
##### 2.5.7.6.1
In-built torsional effects: When there is in-built eccentricity between centre of mass and centre of rigidity (lateral resistance) at floor levels, rigid diaphragms at each level will be subject to torsional moment $M_t$.
##### 2.5.7.6.2
Accidental torsional effects: In order to account for uncertainties in the location of masses and in the spatial variation of the seismic motion, accidental torsional effects need to be always considered. The accidental moment $M_{ta}$ is determined assuming the storey mass to be displaced from the calculated centre of mass a distance equal to 5 percent of the building dimension at that level perpendicular to the direction of the force under consideration. The accidental torsional moment $M_{tai}$ at level $i$ is given as:
$$
M_{tai} = e_{ai}F_i \tag{6.2.43}
$$
Where,
*eai* = accidental eccentricity of floor mass at level i applied in the same direction at all floors $= \pm 0.05L_i$
$L_i =$ floor dimension perpendicular to the direction of seismic force considered.
Where torsional irregularity exists (Sec 2.5.5.3.1) for Seismic Design Category C or D, the irregularity effects shall be accounted for by increasing the accidental torsion $M_{ta}$ at each level by a torsional amplification factor, $A_x$ as illustrated in Figure 6.2.29 determined from the following equation:
$$
A_x = \left[\frac{\delta_{max}}{1.2\delta_{avg}}\right]^2 \leq 3.0 \tag{6.2.44}
$$
Where,
$\delta_{max} =$ Maximum displacement at level-x computed assuming $A_x = 1$.
$\delta_{avg} =$ Average displacements at extreme points of the building at level-x computed assuming $A_x = 1$.
The accidental torsional moment need not be amplified for structures of lightframe construction. Also the torsional amplification factor ($A_x$) should not exceed 3.0.
##### 2.5.7.6.3
Design for torsional effects: The torsional design moment at a given storey shall be equal to the accidental torsional moment $M_{ta}$ plus the inbuilt torsional moment $M_t$ (if any). Where earthquake forces are applied concurrently in two orthogonal directions, the required 5 percent displacement of the center of mass (for accidental torsion) need not be applied in both of the orthogonal directions at the same time, but shall be applied in only one direction that produces the greater effect.
![Torsional amplification factor Ax for plan irregularity]()
Figure 6.2.29 Torsional amplification factor Ax for plan irregularity.
#### 2.5.7.7 Deflection and storey drift
The deflections ($\delta_x$) of level $x$ at the center of the mass shall be determined in accordance with the following equation:
$$
\delta_x = \frac{C_d\delta_{xe}}{I} \tag{6.2.45}
$$
Where,
$C_d =$ Deflection amplification factor given in Table 6.2.19
$\delta_{xe} =$ Deflection determined by an elastic analysis
$I =$ Importance factor defined in Table 6.2.17
The design storey drift at storey $x$ shall be computed as the difference of the deflections at the centers of mass at the top and bottom of the story under consideration:
$$
\Delta_x = \delta_x - \delta_{x-1} \tag{6.2.46}
$$
#### 2.5.7.8 Overturning effects
The structure shall be designed to resist overturning effects caused by the seismic forces determined in Sec 2.5.7.4. At any story, the increment of overturning moment in the story under consideration shall be distributed to the various vertical force resisting elements in the same proportion as the distribution of the horizontal shears to those elements. The overturning moments at level $x$, $M_x$ shall be determined as follows:
$$
M_x = \sum_{i=x}^{n}F_i(h_i-h_x) \tag{6.2.47}
$$
Where,
$F_i =$ Portion of the seismic base shear, $V$ induced at level $i$
$h_i, h_x =$ Height from the base to level $i$ or $x$.
The foundations of structures, except inverted pendulum-type structures, shall be permitted to be designed for three-fourths of the foundation overturning design moment, $M_o$ determined using above equation.
#### 2.5.7.9 P-delta effects
The P-delta effects on story shears and moments, the resulting member forces and moments, and the story drifts induced by these effects are not required to be considered if the stability coefficient (θ) determined by the following equation is not more than 0.10:
$$
\theta = \frac{P_x\Delta}{V_xh_{sx}C_d} \tag{6.2.48}
$$
Where,
* $P_x =$ Total vertical design load at and above level $x$; where computing $P_x$, no individual load factor need exceed 1.0
* $\Delta =$ Design story drift occurring simultaneously with $V_x$
* $V_x =$ Storey shear force acting between levels $x$ and $x-1$
* $h_{sx} =$ Storey height below level $x$
* $C_d =$ Deflection amplification factor given in Table 6.2.19
The stability coefficient $\theta$ shall not exceed $\theta_{max}$ determined as follows:
$$
\theta_{max} = \frac{0.5}{\beta C_d} \leq 0.25 \tag{6.2.49}
$$
Where, $\beta$ is the ratio of shear demand to shear capacity for the story between levels $x$ and $x-1$. This ratio is permitted to be conservatively taken as 1.0.
Where, the stability coefficient $\theta$ is greater than 0.10 but less than or equal to $\theta_{max}$, the incremental factor related to P-delta effects on displacements and member forces shall be determined by rational analysis. Alternatively, it is permitted to multiply displacements and member forces by $\frac{1}{(1-\theta)}$.
Where, $\theta$ is greater than $\theta_{max}$, the structure is potentially unstable and shall be redesigned.
Where, the P-delta effect is included in an automated analysis, Eq. 6.2.49 shall still be satisfied, however, the value of $\theta$ computed from Eq. 6.2.48 using the results of the P-delta analysis is permitted to be divided by (1 + $\theta$) before checking Eq. 6.2.49.
### 2.5.8 Dynamic Analysis Methods
Dynamic analysis method involves applying principles of structural dynamics to compute the response of the structure to applied dynamic (earthquake) loads.
#### 2.5.8.1 Requirement for dynamic analysis
Dynamic analysis should be performed to obtain the design seismic force, and its distribution to different levels along the height of the building and to the various lateral load resisting elements, for the following buildings:
* (a) Regular buildings with height greater than 40 m in Zones 2, 3, 4 and greater than 90 m in Zone 1.
* (b) Irregular buildings (as defined in Sec 2.5.5.3) with height greater than 12 m in Zones 2, 3, 4 and greater than 40 m in Zone 1.
For irregular buildings, smaller than 40 m in height in Zone 1, dynamic analysis, even though not mandatory, is recommended.
#### 2.5.8.2 Methods of analysis
Dynamic analysis may be carried out through the following two methods:
* (i) Response Spectrum Analysis method is a linear elastic analysis method using modal analysis procedures, where the structure is subjected to spectral accelerations corresponding to a design acceleration response spectrum. The design earthquake ground motion in this case is represented by its response spectrum.
* (ii) Time History Analysis method is a numerical integration procedure where design ground motion time histories (acceleration record) are applied at the base of the structure. Time history analysis procedures can be two types: linear and non-linear.
### 2.5.9 Response Spectrum Analysis (RSA)
A response spectrum analysis shall consist of the analysis of a linear mathematical model of the structure to determine the maximum accelerations, forces, and displacements resulting from the dynamic response to ground shaking represented by the design acceleration response spectrum (presented in Sec 2.5.4.3). Response spectrum analysis is also called a modal analysis procedure because it considers different modes of vibration of the structure and combines effects of different modes.
#### 2.5.9.1 Modeling (RSA)
A mathematical model of the structure shall be constructed that represents the spatial distribution of mass and stiffness throughout the structure. For regular structures with independent orthogonal seismic-force-resisting systems, independent two-dimensional models are permitted to be constructed to represent each system. For irregular structures or structures without independent orthogonal systems, a three-dimensional model incorporating a minimum of three dynamic degrees of freedom consisting of translation in two orthogonal plan directions and torsional rotation about the vertical axis shall be included at each level of the structure. Where the diaphragms are not rigid compared to the vertical elements of the lateral-force-resisting system, the model should include representation of the diaphragm’s flexibility and such additional dynamic degrees of freedom as are required to account for the participation of the diaphragm in the structure’s dynamic response. The structure shall be considered to be fixed at the base or, alternatively, it shall be permitted to use realistic assumptions with regard to the stiffness of foundations. In addition, the model shall comply with the following:
* (a) Stiffness properties of concrete and masonry elements shall consider the effects of cracked sections
* (b) The contribution of panel zone deformations to overall story drift shall be included for steel moment frame resisting systems.
#### 2.5.9.2 Number of modes (RSA)
An analysis shall be conducted using the masses and elastic stiffnesses of the seismic-force-resisting system to determine the natural modes of vibration for the structure including the period of each mode, the modal shape vector k, the modal participation factor P and modal mass M. The analysis shall include a sufficient number of modes to obtain a combined modal mass participation of at least 90 percent of the actual mass in each of two orthogonal directions.
#### 2.5.9.3 Modal story shears and moments (RSA)
For each mode, the story shears, story overturning moments, and the shear forces and overturning moments in vertical elements of the structural system at each level due to the seismic forces shall be computed. The peak lateral force $F_{ik}$ induced at level $i$ in mode $k$ is given by:
$$
F_{ik} = A_k \phi_{ik} P_k W_i \tag{6.2.50}
$$
Where,
* $A_k$ = Design horizontal spectral acceleration corresponding to period of vibration $T_k$ of mode $k$ obtained from design response spectrum (Sec 2.5.4.3)
$\phi_{ik}$ = Modal shape coefficient at level $i$ in mode $k$
* $P_k$ = Modal participation factor of mode $k$
* $W_i$ = Weight of floor $i$.
#### 2.5.9.4 Structure response (RSA)
In the response spectrum analysis method, the base shear $V_{rs}$; each of the story shear, moment, and drift quantities; and the deflection at each level shall be determined by combining their modal values. The combination shall be carried out by taking the square root of the sum of the squares (SRSS) of each of the modal values or by the complete quadratic combination (CQC) technique. The complete quadratic combination shall be used where closely spaced periods in the translational and torsional modes result in cross-correlation of the modes.
The distribution of horizontal shear shall be in accordance with the requirements of Sec 2.5.7.5. It should be noted that amplification of accidental torsion as per Sec 2.5.7.6 is not required where accidental torsional effects are included in the dynamic analysis model by offsetting the centre of mass in each story by the required amount.
A base shear, $V$ shall also be calculated using the equivalent static force procedure in Sec 2.5.7. Where the base shear, $V_{rs}$ is less than 85 percent of $V$, all the forces but not the drifts obtained by response spectrum analysis shall be multiplied by the ratio $\dfrac{0.85V}{V_{rs}}$.
The displacements and drifts obtained by response spectrum analysis shall be multiplied by $C_d/I$ to obtain design displacements and drifts, as done in equivalent static analysis procedure (Sec 2.5.7.7). The P-delta effects shall be determined in accordance with Sec 2.5.7.9.
### 2.5.10 Linear Time History Analysis (LTHA)
A linear time history analysis (LTHA) shall consist of an analysis of a linear mathematical model of the structure to determine its response, through direct numerical integration of the differential equations of motion, to a number of ground motion acceleration time histories compatible with the design response spectrum for the site. The analysis shall be performed in accordance with the provisions of this Section. For the purposes of analysis, the structure shall be permitted to be considered to be fixed at the base or, alternatively, it shall be permitted to use realistic assumptions with regard to the stiffness of foundations. The acceleration time history (ground motion) is applied at the base of the structure. The advantage of this procedure is that the time dependent behavior of the structural response is obtained.
#### 2.5.10.1 Modeling (LTHA)
Mathematical models shall conform to the requirements of modeling described in Sec 2.5.9.1.
#### 2.5.10.2 Ground motion (LTHA)
At least three appropriate ground motions (acceleration time history) shall be used in the analysis. Ground motion shall conform to the requirements of this Section.
Two-dimensional analysis: Where two-dimensional analyses are performed, each ground motion shall consist of a horizontal acceleration time history selected from an actual recorded event. Appropriate acceleration histories shall be obtained from records of events having magnitudes, fault distance, and source mechanisms that are consistent with those that control the maximum considered earthquake. Where the required number of appropriate ground motion records are not available, appropriate simulated ground motion time histories shall be used to make up the total number required. The ground motions shall be scaled such that for each period between 0.2T and 1.5T (where T is the natural period of the structure in the fundamental mode for the direction considered) the average of the five-percent-damped response spectra for the each acceleration time history is not less than the corresponding ordinate of the design acceleration response spectrum, determined in accordance with Sec 2.5.4.3.
Three-dimensional analysis: Where three-dimensional analysis is performed, ground motions shall consist of pairs of appropriate horizontal ground motion acceleration time histories (in two orthogonal horizontal directions) that shall be selected and scaled from individual recorded events. Appropriate ground motions shall be selected from events having magnitudes, fault distance, and source mechanisms that are consistent with those that control the maximum considered earthquake. Where the required number of recorded ground motion pairs are not available, appropriate simulated ground motion pairs shall be used to make up the total number required. For each pair of horizontal ground motion components, an SRSS spectrum shall be constructed by taking the square root of the sum of the squares of the five-percent-damped response spectra for the components (where an identical scale factor is applied to both components of a pair). Each pair of motions shall be scaled such that for each period between 0.2T and 1.5T (where T is the natural period of the fundamental mode of the structure) the average of the SRSS spectra from all horizontal component pairs is not less than 1.3 times the corresponding ordinate of the design response spectrum, determined in accordance with Sec 2.5.4.3.
#### 2.5.10.3 Structure response (LTHA)
For each scaled acceleration time history, the maximum values of base shear and other structure response quantities shall be obtained from the time history analysis. For three dimensional analysis, orthogonal pair of scaled motions are applied simultaneously. A base shear, $V$, shall also be calculated using the equivalent static force procedure described in Sec 2.5.7.1. Where the maximum base shear, $V_{th}$ computed by linear time history analysis, is less than $V$, all response quantities (storey shear, moments, drifts, floor deflections, member forces etc) obtained by time history analysis shall be increased by multiplying with the ratio, $\dfrac{V}{V_{th}}$. If number of earthquake records (or pairs) used in the analysis is less than seven, the maximum structural response obtained corresponding to different earthquake records shall be considered as the design value. If the number is at least seven, then the average of maximum structural responses for different earthquake records shall be considered as the design value.
The displacements and drifts obtained as mentioned above shall be multiplied +, by µ to obtain design displacements and drifts, as done in equivalent static analysis procedure (Sec 2.5.7.7).
### 2.5.11 Non-Linear Time History Analysis (NTHA)
Nonlinear time history analysis (NTHA) shall consist of analysis of a mathematical model of the structure which incorporates the nonlinear hysteretic behavior of the structure’s components to determine its response, through methods of numerical integration, to ground acceleration time histories compatible with the design response spectrum for the site. The analysis shall be performed in accordance with the requirements of this Section. For the purposes of analysis, the structure shall be permitted to be considered to be fixed at the base or, alternatively, it shall be permitted to use realistic assumptions with regard to the stiffness of foundations. The acceleration time history (ground motion) is applied at the base of the structure. The advantage of this procedure is that actual time dependent behavior of the structural response considering inelastic deformations in the structure can be obtained.
#### 2.5.11.1 Modeling (NTHA)
A mathematical model of the structure shall be constructed that represents the spatial distribution of mass throughout the structure. The hysteretic behavior of elements shall be modeled consistent with suitable laboratory test data and shall account for all significant yielding, strength degradation, stiffness degradation, and hysteretic pinching indicated by such test data. Strength of elements shall be based on expected values considering material over-strength, strain hardening, and hysteretic strength degradation. As a minimum, a bilinear force deformation relationship should be used at the element level. In reinforced concrete and masonry buildings, the elastic stiffness should correspond to that of cracked sections. Linear properties, consistent with the provisions of Chapter 5 shall be permitted to be used for those elements demonstrated by the analysis to remain within their linear range of response. The structure shall be assumed to have a fixed base or, alternatively, it shall be permitted to use realistic assumptions with regard to the stiffness and load carrying characteristics of the foundations consistent with site-specific soils data and rational principles of engineering mechanics.
For regular structures with independent orthogonal seismic-force-resisting systems, independent two dimensional models shall be permitted to be constructed to represent each system. For structures having plan irregularity or structures without independent orthogonal systems, a three-dimensional model incorporating a minimum of three dynamic degrees of freedom consisting of
translation in two orthogonal plan directions and torsional rotation about the vertical axis at each level of the structure shall be used. Where the diaphragms are not rigid compared to the vertical elements of the lateral-force-resisting system, the model shall include representation of the diaphragm’s flexibility and such additional dynamic degrees of freedom as are required to account for the participation of the diaphragm in the structure’s dynamic response.
#### 2.5.11.2 Ground motion (NTHA)
The actual time-dependent inelastic deformation of the structure is modeled. For inelastic analysis method, the real design acceleration response spectrum (Sec 2.5.4.3) is obtained using Eq. 6.2.34 with R51 and I51. The real design acceleration response spectrum is the true representation of the expected ground motion (design basis earthquake) including local soil effects and corresponds to a peak ground acceleration (PGA) value of KC. 2
At least three appropriate acceleration time histories shall be used in the analysis. Ground motion shall conform to the requirements of this Section.
**Two-dimensional analysis**
Where two-dimensional analyses are performed, each ground motion shall consist of a horizontal acceleration time history selected from an actual recorded event. Appropriate acceleration histories shall be obtained from records of events having magnitudes, fault distance, and source mechanisms that are consistent with those that control the maximum considered earthquake. Where the required number of appropriate ground motion records are not available, appropriate simulated ground motion time histories shall be used to make up the total number required. The ground motions shall be scaled such that for each period between 0.2T and 1.5T (where T is the natural period of the structure in the fundamental mode for the direction considered) the average of the five-percent-damped response spectra for each acceleration time history is not less than the corresponding ordinate of the real design acceleration response spectrum, as defined here.
**Three-dimensional analysis**
Where three-dimensional analysis is performed, ground motions shall consist of pairs of appropriate horizontal ground motion acceleration time histories (in two orthogonal horizontal directions) that shall be selected and scaled from individual recorded events. Appropriate ground motions shall be selected from
events having magnitudes, fault distance, and source mechanisms that are consistent with those that control the maximum considered earthquake. Where the required number of recorded ground motion pairs are not available, appropriate simulated ground motion pairs shall be used to make up the total number required. For each pair of horizontal ground motion components, an SRSS spectrum shall be constructed by taking the square root of the sum of the squares of the five-percent-damped response spectra for the components (where an identical scale factor is applied to both components of a pair). Each pair of motions shall be scaled such that for each period between 0.2T and 1.5T (where T is the natural period of the fundamental mode of the structure) the average of the SRSS spectra from all horizontal component pairs is not less than 1.3 times the corresponding ordinate of the real design acceleration response spectrum.
#### 2.5.11.3 Structure response (NTHA)
For each scaled acceleration time history, the maximum values of base shear and other structure response quantities shall be obtained from the nonlinear time history analysis. For three dimensional analysis, orthogonal pair of scaled motions are applied simultaneously. If number of earthquake records (or pairs) used in the analysis is less than seven, the maximum structural response obtained corresponding to different earthquake records shall be considered as the design value. If the number is at least seven, then the average of maximum structural responses for different earthquake records shall be considered as the design value. Since real expected earthquake motion input and model incorporating real nonlinear behavior of the structure is used, the results as obtained are directly used (no scaling as in LTHA or RSA is required) for interpretation and design.
#### 2.5.11.4 Structure member design (NTHA)
The adequacy of individual members and their connections to withstand the design deformations predicted by the analyses shall be evaluated based on laboratory test data for similar components. The effects of gravity and other loads on member deformation capacity shall be considered in these evaluations. Member deformation shall not exceed two thirds of the smaller of: the value that results in loss of ability to carry gravity loads or the value at which member strength has deteriorated to less than 67 percent of peak strength.
#### 2.5.11.5 Design review (NTHA)
Special care and expertise is needed in the use of nonlinear dynamic analysis based design. Checking of the design by competent third party is recommended. A review of the design of the seismic-force-resisting system and the supporting structural analyses shall be performed by an independent team consisting of design professionals with experience in seismic analysis methods and the theory and application of nonlinear seismic analysis and structural behavior under extreme cyclic loads. The design review shall include the following: (i) Review of development of ground motion time histories (ii) Review of acceptance criteria (including laboratory test data) used to demonstrate the adequacy of structural elements and systems to withstand the calculated force and deformation demands (iii) Review of structural design.
### 2.5.12 Non-Linear Static Analysis (NSA)
Nonlinear static analysis (NSA), also popularly known as pushover analysis, is a simplified method of directly evaluating nonlinear response of structures to strong earthquake ground shaking. It is an alternative to the more complex nonlinear time history analysis (NTHA). The building is subjected to monotonically increasing static horizontal loads under constant gravity load.
#### 2.5.12.1 Modeling (NSA)
A mathematical model of the structure shall be constructed to represent the spatial distribution of mass and stiffness of the structural system considering the effects of element nonlinearity for deformation levels that exceed the proportional limit. P-Delta effects shall also be included in the analysis.
For regular structures with independent orthogonal seismic-force-resisting systems, independent two-dimensional models may be used to represent each system. For structures having plan irregularities or structures without independent orthogonal systems, a three-dimensional model incorporating a minimum of three degrees of freedom for each level of the structure, consisting of translation in two orthogonal plan directions and torsional rotation about the vertical axis, shall be used. Where the diaphragms are not rigid compared to the vertical elements of the seismic-force-resisting system, the model should include representation of the diaphragm flexibility.
Unless analysis indicates that an element remains elastic, a nonlinear force deformation model shall be used to represent the stiffness of the element before onset of yield, the yield strength, and the stiffness properties of the element after yield at various levels of deformation. Strengths of elements shall not
exceed expected values considering material over-strength and strain hardening. The properties of elements and components after yielding shall account for strength and stiffness degradation due to softening, buckling, or fracture as indicated by principles of mechanics or test data.
A control point shall be selected for the model. For normal buildings, the control point shall be at the center of mass of the highest level (roof) of the structure.
#### 2.5.12.2 Analysis procedure (NSA)
The lateral forces shall be applied at the center of mass of each level and shall be proportional to the distribution obtained from a modal analysis for the fundamental mode of response in the direction under consideration. The lateral loads shall be increased incrementally in a monotonic manner.
At the $j^{th}$ increment of lateral loading, the total lateral force applied to the model shall be characterized by the term $V_j$. The incremental increases in applied lateral force should be in steps that are sufficiently small to permit significant changes in individual element behavior (such as yielding, buckling or failure) to be detected. The first increment in lateral loading shall result in linear elastic behavior. At each loading step, the total applied lateral force, $V_j$ the lateral displacement of the control point, $\delta_j$ and the forces and deformations in each element shall be recorded. The analysis shall be continued until the displacement of the control point is at least 150 percent of the target displacement determined in accordance with Sec.2.5.12.3. The structure shall be designed so that the total applied lateral force does not decrease in any load increment for control point displacements less than or equal to 125 percent of the target displacement.
#### 2.5.12.3 Effective period and target displacement (NSA)
A bilinear curve shall be fitted to the capacity curve, such that the first segment of the bilinear curve coincides with the capacity curve at 60 percent of the effective yield strength, the second segment coincides with the capacity curve at the target displacement, and the area under the bilinear curve equals the area under the capacity curve, between the origin and the target displacement. The effective yield strength, $V_y$ corresponds to the total applied lateral force at the intersection of the two line segments. The effective yield displacement, $\delta_y$ corresponds to the control point displacement at the intersection of the two line segments. The effective fundamental period, $T_e$ of the structure in the direction under consideration shall be determined using Eq. 6.2.51 as follows:
$$
T_e = T_1\sqrt{\frac{V_1/\delta_1}{V_y/\delta_y}} \tag{6.2.51}
$$
Where, $V_1$, $\delta_1$, and $T_1$ are determined for the first increment of lateral load. The target displacement of the control point, $\delta_T$ shall be determined as follows:
$$
\delta_T = C_0C_1S_a\left(\frac{T_e}{2\pi}\right)^2g \tag{6.2.52}
$$
Where, the spectral acceleration, $S_a$, is determined at the effective fundamental period, $T_e$, using Eq. 6.2.34, $g$ is the acceleration due to gravity. The coefficient $C_o$ shall be calculated as :
$$
C_o = \frac{\sum\limits_{i=1}^{n} w_i\phi_i}{\sum\limits_{i=1}^{n} w_i\phi_i^2} \tag{6.2.53}
$$
Where,
$w_i$ = the portion of the seismic weight, W, at level i, and
$\phi_i$ = the amplitude of the shape vector at level i.
Where the effective fundamental period, $T_e$, is greater than $T_C$ (defined in Sec. 2.5.4.3), the coefficient $C_1$ shall be taken as 1.0. Otherwise, the value of the coefficient $C_1$ shall be calculated as follows:
$$
C_1 = \frac{1}{R_d}\left(1 + \frac{(R_d-1)T_s}{T_e}\right) \tag{6.2.54}
$$
Where, $R_d$ is given as follows:
$$
R_d = \frac{S_a}{V_y/W} \tag{6.2.55}
$$
#### 2.5.12.4 Structure member design (NSA)
For each nonlinear static analysis the design response parameters, including the individual member forces and member deformations shall be taken as the values obtained from the analysis at the step at which the target displacement is reached.
The adequacy of individual members and their connections to withstand the member forces and member deformations shall be evaluated based on laboratory test data for similar components. The effects of gravity and other loads on member deformation capacity shall be considered in these evaluations. The deformation of a member supporting gravity loads shall not exceed (i) twothirds of the deformation that results in loss of ability to support gravity loads, and (ii) two-thirds of the deformation at which the member strength has deteriorated to less than 70 percent of the peak strength of the component model. The deformation of a member not required for gravity load support shall not exceed two-thirds of the value at which member strength has deteriorated to less than 70 percent of the peak strength of the component model.
#### 2.5.12.5 Design review (NSA)
Checking of the design by competent third party is recommended. An independent team composed of at least two members with experience in seismic analysis methods and the theory and application of nonlinear seismic analysis and structural behavior under earthquake loading, shall perform a review of the design of the seismic force resisting system and the supporting structural analyses. The design review shall include (i) review of any sitespecific seismic criteria (if developed) employed in the analysis (ii) review of the determination of the target displacement and effective yield strength of the structure (iii) review of adequacy of structural elements and systems to withstand the calculated force and deformation demands, together with laboratory and other data (iv) review of structural design.
### 2.5.13 Earthquake Load Effects and Load Combinations
The seismic load effect, E, shall be determined in accordance with the following:
1. For use in load combination 5 in Section 2.7.3 or load combination 5 and 6 in Section 2.7.2, E shall be determined in accordance with the following equation,
E 5 Eh + Ev
2. For use in load combination 7 in Section 2.7.3 or load combination 8 in Section 2.7.2, E shall be determined in accordance with following equation, E 5 Eh − Ev
Where,
E 5 total seismic load effect
Eh 5 effect of horizontal seismic forces as defined in Sections 2.5.7 or 2.5.9
Ev 5 effect of vertical seismic forces as defined in Section 2.5.13.2
#### 2.5.13.1 Horizontal earthquake loading, Eh
The horizontal seismic load effect, Eh, shall be taken as the horizontal load effects of seismic base shear V (Sec 2.5.7 or 2.5.9) or component forces Fc (Sec 2.5.15).
The directions of application of horizontal seismic forces for design shall be those which will produce the most critical load effects. Earthquake forces act in both principal directions of the building simultaneously. In order to account for that,
* (a) For structures of Seismic Design Category B, the design horizontal seismic forces are permitted to be applied independently in each of two orthogonal directions and orthogonal interaction effects are permitted to be neglected
* (b) Structures of Seismic Design Category C and D shall, as a minimum, conform to the requirements of (a) for Seismic Design Category B and in addition the requirements of this Section. The structure of Seismic Design Category C with plan irregularity type V and Seismic Design Category D shall be designed for 100% of the horizontal seismic forces in one principal direction combined with 30% of the horizontal seismic forces in the orthogonal direction. Possible combinations are:
* “±100% in x-direction ±30% in y-direction” or
“±30% in x-direction ±100% in y-direction”
The combination which produces most unfavourable effect for the particular action effect shall be considered. This approach may be applied to equivalent static analysis, response spectrum analysis and linear time history analysis procedure.
* (c) Where three-dimensional analysis of a spatial structure model is performed as in 3D time history analysis, simultaneous application of accelerations in two directions shall be considered where the ground motions shall satisfy the conditions stated in Sections 2.5.10.2 or 2.5.11.2.
#### 2.5.13.2 Vertical earthquake loading, Ev
The maximum vertical ground acceleration shall be taken as 50 percent of the expected horizontal peak ground acceleration (PGA). The vertical seismic load effect %¼ may be determined as:
%¼ 5 0.50(L3)#
(6.2.56)
Where,
* L3 5 expected horizontal peak ground acceleration (in g) for design 5 (2/3)KC
* # 5 effect of dead load, S 5 site dependent soil factor (see Table 6.2.16).
#### 2.5.13.3 Combination of earthquake loading with other loadings
When earthquake effect is included in the analysis and design of a building or structure, the provisions set forth in Sec 2.7 shall be followed to combine earthquake load effects, both horizontal and vertical, with other loading effects to obtain design forces etc.
#### 2.5.13.4 Seismic Load Effect Including Overstrength Factor
Where specifically required, conditions requiring overstrength factor, Ωo, applications shall be determined in accordance with the following,
1. For use in load combination 5 in Section 2.7.3 or load combinations 5 and 6 in Section 2.7.2, E shall be taken equal to Em as determined in accordance with the following equation,
Em 5 Emh+ Ev
2. For use in load combination 7 in Section 2.7.3 or load combination 8 in Section 2.7.2, E shall be taken equal to Em as determined in accordance with the following equation,
Em 5 Emh − Ev
where
Em 5 total seismic load effect including overstrength factor
* Emh 5 effect of horizontal seismic forces as defined in Sections 2.5.7 or 2.5.9 including structural overstrength.
* Ev 5 effect of vertical seismic forces as defined in Section 2.5.13.2
The horizontal seismic load effect with overstrength factor, Emh, shall be determined in accordance with the following equation:
Emh 5 ΩoEh
Where, Ωo is the system overstrength factor as defined in Table 6.2.19. Like Eh, directional combinations as defined in Sec. 2.5.13.1.(b) is also applicable for calculating Emh. The value of Emh need not exceed the maximum force that can develop in the structure or element as determined by a rational, plastic mechanism analysis or nonlinear response analysis (static or dynamic) utilizing realistic expected values of material strengths.
#### 2.5.13.5 Allowable Stress Increase for Load Combinations with Overstrength
Where allowable stress design methodologies are used with the seismic load effect defined in Section 2.5.13.4 applied in load combinations 5, 6, or 8 of Section 2.7.2, allowable stresses are permitted to be determined using an allowable stress increase of 1.2. This increase shall not be combined with increases in allowable stresses or load combination reductions otherwise permitted elsewhere by this standard.
#### 2.5.13.6 Minimum Upward Force for Horizontal Cantilevers for Seismic Design Category D
In structures assigned to Seismic Design Category D, horizontal cantilever structural components shall be designed for a minimum net upward force of 0.2 times the dead load in addition to the applicable load combinations of Section 2.7.
### 2.5.14 Drift and Deformation
#### 2.5.14.1 Storey drift limit
The design storey drift (Δ) of each storey, as determined in Sections 2.5.7, 2.5.9 or 2.5.10 shall not exceed the allowable storey drift (Δa) as obtained from Table 6.2.21 for any story.
For structures with significant torsional deflections, the maximum drift shall include torsional effects. For structures assigned to Seismic Design Category C or D having torsional irregularity, the design storey drift, shall be computed as the largest difference of the deflections along any of the edges of the structure at the top and bottom of the storey under consideration. For seismic force–resisting systems comprised solely of moment frames in Seismic Design Categories D, the allowable storey drift for such linear elastic analysis procedures shall not exceed Δ'/. where . is termed as a structural redundancy factor. The value of redundancy factor . may be considered as 1.0 with exception of structures of very low level of redundancy where . may be considered as 1.3.
For nonlinear time history analysis (NTHA), the storey drift obtained (Sec 2.5.11) shall not exceed 1.25 times the storey drift limit specified above for linear elastic analysis procedures.
#### 2.5.14.2 Diaphragm deflection
The deflection in the plane of the diaphragm, as determined by engineering analysis, shall not exceed the permissible deflection of the attached elements. Permissible deflection shall be that deflection that will permit the attached element to maintain its structural integrity under the individual loading and continue to support the prescribed loads.
Table 6.2.21: Allowable Storey Drift Limit ( /ú )
| Structure | Occ | upancy Categ | ory |
| ------------------------------------------------------------------------------------------------------------------------------- | -------- | ------------ | ------ |
| | I and II | III | IV |
| Structures, other than masonry shear | | | |
| wall structures, 4 stories or less with
interior walls, partitions, ceilings and
exterior wall systems that have been | 0.025ℎ | 0.020ℎ | 0.015ℎ |
| designed to accommodate the story | | | |
| drifts. | | | |
| Masonry cantilever shear wall structures | 0.010ℎ | 0.010ℎ | 0.010ℎ |
| Other masonry shear wall structures | 0.007ℎ | 0.007ℎ | 0.007ℎ |
| All other structures | 0.020ℎ | 0.015ℎ | 0.010ℎ |
| Notes: | | | |
* 1.ℎis the story height below Level .
* 2.There shall be no drift limit for single-story structures with interior walls, partitions, ceilings, and exterior wall systems that have been designed to accommodate the storey drifts.
* 3.Structures in which the basic structural system consists of masonry shear walls designed as vertical elements cantilevered from their base or foundation support which are so constructed that moment transfer between shear walls (coupling) is negligible.
* 4.Occupancy categories are defined in Table 6.1.1
#### 2.5.14.3 Separation between adjacent structures
Buildings shall be protected from earthquake-induced pounding from adjacent structures or between structurally independent units of the same building maintaining safe distance between such structures as follows:
* (i) for buildings, or structurally independent units, that do not belong to the same property, the distance from the property line to the potential points of impact shall not be less than the computed maximum horizontal displacement (Sec 2.5.7.7) of the building at the corresponding level.
* (ii) for buildings, or structurally independent units, belonging to the same property, if the distance between them is not less than the square root of the sum of the squares (SRSS) of the computed maximum horizontal displacements (Sec 2.5.7.7) of the two buildings or units at the corresponding level.
* (iii) if the floor elevations of the building or independent unit under design are the same as those of the adjacent building or unit, the above referred minimum distance may be reduced by a factor of 0.7
#### 2.5.14.4 Special deformation requirement for seismic design category D
For structures assigned to Seismic Design Category D, every structural component not included in the seismic force–resisting system in the direction under consideration shall be designed to be adequate for the gravity load effects and the seismic forces resulting from displacement to the design story drift (Δ) as determined in accordance with Sec 2.5.7.7. Even where elements of the structure are not intended to resist seismic forces, their protection may be important. Where determining the moments and shears induced in components that are not included in the seismic force–resisting system in the direction under consideration, the stiffening effects of adjoining rigid structural and nonstructural elements shall be considered and a rational value of member and restraint stiffness shall be used.
### 2.5.15 Seismic Design For Nonstructural Components
This Section establishes minimum design criteria for nonstructural components that are permanently attached to structures and for their supports and attachments. The following components are exempt from the requirements of this Section.
* (1) Architectural components in Seismic Design Category B, other than parapets supported by bearing walls or shear walls, where the component importance factor, .+ is equal to 1.0.
* (2) Mechanical and electrical components in Seismic Design Category B.
* (3) Mechanical and electrical components in Seismic Design Category C where the importance factor, .+ is equal to 1.0.
* (4) Mechanical and electrical components in Seismic Design Category D where the component importance factor, .+ is equal to 1.0 and either (a) flexible connections between the components and associated ductwork, piping, and conduit are provided, or (b) components are mounted at 1.2 m or less above a floor level and weigh 1780 N or less.
* (5) Mechanical and electrical components in Seismic Design Category C or D where the component importance factor, .+ is equal to 1.0 and (a) flexible connections between the components and associated ductwork, piping, and conduit are provided, and (b) the components weigh 89 N or less or, for distribution systems, which weigh 73 N/m or less.
Where the individual weight of supported components and non-building structures with periods greater than 0.06 seconds exceeds 25 percent of the total seismic weight W, the structure shall be designed considering interaction effects between the structure and the supported components.
Testing shall be permitted to be used in lieu of analysis methods outlined in this Chapter to determine the seismic capacity of components and their supports and attachments.
#### 2.5.15.1 Component importance factor
All components shall be assigned a component importance factor. The component importance factor, .+ shall be taken as 1.5 if any of the following conditions apply:
* (1) The component is required to function after an earthquake,
* (2) The component contains hazardous materials, or
* (3) The component is in or attached to a occupancy category IV building and it is needed for continued operation of the facility.
All other components shall be assigned a component importance factor, .+ equal to 1.0.
#### 2.5.15.2 Component force transfer
Components shall be attached such that the component forces are transferred to the structure. Component attachments that are intended to resist seismic forces shall be bolted, welded, or otherwise positively fastened without consideration of frictional resistance produced by the effects of gravity. A continuous load path of sufficient strength and stiffness between the component and the supporting structure shall be verified. Local elements of the supporting structure shall be designed for the component forces where such forces control the design of the elements or their connections. In this instance, the component forces shall be those determined in Sec 2.5.15.3, except that modifications to &! and @! due to anchorage conditions need not be considered. The design documents shall include sufficient information concerning the attachments to verify compliance with the requirements of these Provisions.
#### 2.5.15.3 Seismic design force
The seismic design force, Fc, applied in the horizontal direction shall be centered at the component’s center of gravity and distributed relative to the component's mass distribution and shall be determined as follows:
Where,
0.75L3I+.+ ≤&+ ≤1.5L3I+.+
a+ 5 component amplification factor which varies from 1.0 to 2.5 (Table 6.2.22 or Table 6.2.23).
L3 5 expected horizontal peak ground acceleration (in g) for design 5 0.67ZS
I+ 5 weight of component
@+ 5 component response reduction factor which varies from 1.0 to 12.0 (Table 6.2.22 or Table 6.2.23)
4 5 height above the base of the point of attachment of the component, but z shall not be taken less than 0 and the value of 4/ℎ need not exceed 1.0
h 5 roof height of structure above the base
The force &+ shall be independently applied in at least two orthogonal horizontal directions in combination with service loads associated with the component. In addition, the component shall also be designed for a concurrent vertical force of ± 0.5ahWc.
Where non-seismic loads on nonstructural components exceed &+ such loads shall govern the strength design, but the seismic detailing requirements and limitations shall apply.
#### 2.5.15.4 Seismic relative displacements
The relative seismic displacement, #+ for two connection points on the same structure A, one at a height ℎ and other at height ℎH, for use in component design shall be determined as follows:
shall not exceed #+ ' given by:
Where,
* w 5 Deflection at level x of structure A
* Hw 5 Deflection at level y of structure A
* ∆'w 5 Allowable story drift for structure A
* *hx* = Height (above base) of level x to which upper connection point is attached.
* *hy* = Height (above base) of level y to which lower connection point is attached.
* *hsx* = Story height used in the definition of the allowable drift Δa
For two connection points on separate structures, A and B, or separate structural systems, one at level x and the other at level y, Dc shall be determined as follows:
Dc shall not exceed Dc max given by:
Where,
* HA = Deflection at level y of structure B
* ∆'A = Allowable story drift for structure B
The effects of relative seismic relative displacements shall be considered in combination with displacements caused by other loads as appropriate.
### **2.5.16 Design For Seismically Isolated Buildings**
Buildings that use special seismic isolation systems for protection against earthquakes shall be called seismically isolated or base isolated buildings. Seismically isolated structure and every portion thereof shall be designed and constructed in accordance with the requirements of provisions presented in this Section.
#### 2.5.16.1 General requirements for isolation system
The isolation system to be used in seismically isolated structures shall satisfy the following requirements:
* (1) Design of isolation system shall consider variations in seismic isolator material properties over the projected life of structure including changes due to ageing, contamination, exposure to moisture, loadings, temperature, creep, fatigue, etc.
* (2) Isolated structures shall resist design wind loads at all levels above the isolation interface. At the isolation interface, a wind restraint system shall be provided to limit lateral displacement in the isolation system to a value equal to that required between floors of the structure above the isolation interface.
* (3) The fire resistance rating for the isolation system shall be consistent with the requirements of columns, walls, or other such elements in the same area of the structure.
* (4) The isolation system shall be configured to produce a lateral restoring force such that the lateral force at the total design displacement is at least 0.025 W greater than the lateral force at 50% of the total design displacement.
* (5) The isolation system shall not be configured to include a displacement restraint that limits lateral displacement due to the maximum considered earthquake to less than the total maximum displacement unless it is demonstrated by analysis that such engagement of restraint does not result in unsatisfactory performance of the structure.
* (6) Each element of the isolation system shall be designed to be stable under the design vertical load when subjected to a horizontal displacement equal to the total maximum displacement.
* (7) The factor of safety against global structural overturning at the isolation interface shall not be less than 1.0 for required load combinations. All gravity and seismic loading conditions shall be investigated. Seismic forces for overturning calculations shall be based on the maximum considered earthquake and the vertical restoring force shall be based on the seismic weight above the isolation interface.
* (8) Local uplift of individual units of isolation system is permitted if the resulting deflections do not cause overstress or instability of the isolator units or other elements of the structure.
* (9) Access for inspection and replacement of all components of the isolation system shall be provided.
* (10) The designer of the isolation system shall establish a quality control testing program for isolator units. Each isolator unit before installation shall be tested under specified vertical and horizontal loads.
* (11) After completion of construction, a design professional shall complete a final series of inspections or observations of structure separation areas and components that cross the isolation interface. Such inspections and observations shall confirm that existing conditions allow free and unhindered displacement of the structure to maximum design levels and that all components that cross the isolation interface as installed are able to accommodate the stipulated displacements.
* (12) The designer of the isolation system shall establish a periodic monitoring, inspection, and maintenance program for such system.
* (13) Remodeling, repair, or retrofitting at the isolation interface, including that of components that cross the isolation interface, shall be performed under the direction of a design professional experienced in seismic isolation systems.
Table 6.2.22: Coefficients ø0 and 10 for Architectural Components
| Architectural Component or Element | ø0a | 10 |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------- | --------------------- |
| Interior Nonstructural Walls and Partitions | | |
| Plain (unreinforced) masonry walls | 1.0 | 1.5 |
| All other walls and partitions | 1.0 | 2.5 |
| Cantilever Elements (Unbraced or braced to structural frame below its | 2.5 | 2.5 |
| center of mass) Parapets and cantilever interior nonstructural walls | | |
| Chimneys and stacks where laterally braced or supported by the structural
frame | 2.5 | 2.5 |
| Cantilever Elements (Braced to structural frame above its center of mass)
Parapets
Chimneys and Stacks
Exterior Nonstructural Walls | 1.0
1.0
1.0 | 2.5
2.5
2.5 |
| Exterior Nonstructural Wall Elements and Connections | | |
| Wall Element | 1.0 | 2.5 |
| Body of wall panel connections | 1.0 | 2.5 |
| Fasteners of the connecting system | 1.25 | 1.0 |
| Veneer | | |
| Limited deformability elements and attachments | 1.0 | 2.5 |
| Low deformability elements and attachments | 1.0 | 1.5 |
| Penthouses (except where framed by an extension of the building frame) | 2.5 | 3.5 |
| Ceilings | | |
| All | 1.0 | 2.5 |
| Cabinets | | |
| Storage cabinets and laboratory equipment | 1.0 | 2.5 |
| Access Floors | | |
| Special access floors | 1.0 | 2.5 |
| All other | 1.0 | 1.5 |
| Appendages and Ornamentations | 2.5 | 2.5 |
| Signs and Billboards | 2.5 | 2.5 |
| Other Rigid Components | | |
| High deformability elements and attachments | 1.0 | 3.5 |
| Limited deformability elements and attachments | 1.0 | 2.5 |
| Low deformability materials and attachments | 1.0 | 1.5 |
| Other Flexible Components | | |
| High deformability elements and attachments | 2.5 | 3.5 |
| Limited deformability elements and attachments | 2.5 | 2.5 |
| Low deformability materials and attachments | 2.5 | 1.5 |
| a A lower value for αc is permitted where justified by detailed dynamic analysis. The value for αc shall not be less than 1.0. The value of αc equal to 1.0 is for rigid components and rigidly attached components. The value of αc equal to 2.5 is for flexible components and flexibly attached components. | | |
**Table 6.2.23: Coefficients a\_p and R\_p for Mechanical and Electrical Components**
| **Mechanical and Electrical Components** | ø0***a*** | 10 |
| --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------- | ---- |
| Air-side HVAC, fans, air handlers, air conditioning units, cabinet heaters, air
distribution boxes,and othermechanical components constructed of sheet metal
framing. | 2.5 | 6.0 |
| Wet-side HVAC, boilers, furnaces, atmospheric tanks and bins, chillers, water
heaters, heat exchangers, evaporators, air separators, manufacturing or process
equipment, and other mechanical components constructed of high-deformability
materials. | 1.0 | 2.5 |
| Engines, turbines, pumps, compressors, and pressure vessels not supported on
skirts and not within the scope of Chapter 15. | 1.0 | 2.5 |
| Skirt-supported pressure vessels | 2.5 | 2.5 |
| Elevator and escalator components. | 1.0 | 2.5 |
| Generators, batteries, inverters, motors, transformers, and other electrical
components constructed of high deformability materials. | 1.0 | 2.5 |
| Motor control centers, panel boards, switch gear, instrumentation cabinets, and
other componentsconstructed ofsheet metal framing. | 2.5 | 6.0 |
| Communication equipment, computers, instrumentation, and controls. | 1.0 | 2.5 |
| Roof-mounted chimneys, stacks, cooling and electrical towers laterally braced
below their center of mass. | 2.5 | 3.0 |
| Roof-mounted chimneys, stacks, cooling and electrical towers laterally braced
above their center of mass. | 1.0 | 2.5 |
| Lighting fixtures. | 1.0 | 1.5 |
| Other mechanical or electrical components. | 1.0 | 1.5 |
| **Vibration Isolated Components and Systems*****b*** | | |
| Components and systems isolated using neoprene elements and neoprene
isolated floors with built-in or separate elastomeric snubbing devices or resilient
perimeter stops. | 2.5 | 2.5 |
| Spring isolated components and systems and vibration isolated floors closely
restrained using built-in or separate elastomeric snubbing devices or resilient
perimeter stops. | 2.5 | 2.0 |
| Internally isolated components and systems. | 2.5 | 2.0 |
| Suspended vibration isolated equipment including in-line duct devices and
suspended internally isolated components. | 2.5 | 2.5 |
| Air-side HVAC, fans, air handlers, air conditioning units, cabinet heaters, air
distribution boxes, and other mechanical components constructed of sheet metal
framing. | 2.5 | 6.0 |
| Wet-side HVAC, boilers, furnaces, atmospheric tanks and bins, chillers, water
heaters, heat exchangers, evaporators, air separators, manufacturing or process
equipment, and other mechanical components constructed of high-
deformability materials. | 1.0 | 2.5 |
| Engines, turbines, pumps, compressors, and pressure vessels not supported on
skirts and not within the scope of Chapter 15. | 1.0 | 2.5 |
| Skirt-supported pressure vessels | 2.5 | 2.5 |
| **Distribution Systems** | | |
| Piping in accordance with ASME B31, including in-line components with joints
made by welding or brazing. | 2.5 | 12.0 |
| Piping in accordance with ASME B31, including in-line components,
constructed of high or limited deformability materials, with joints made by
threading, bonding, compression couplings, or grooved couplings. | 2.5 | 6.0 |
| Piping and tubing not in accordance with ASME B31, including in-line
components, constructed of high-deformability materials, with joints made by
welding or brazing. | 2.5 | 9.0 |
| Piping and tubing not in accordance with ASME B31, including in-line
components, constructed of high- or limited-deformability materials, with joints
made by threading, bonding, compression couplings, or grooved couplings. | 2.5 | 4.5 |
| Piping and tubing constructed of low-deformability materials, such as cast iron,
glass, and non-ductile plastics. | 2.5 | 3.0 |
| Ductwork, including in-line components, constructed of high-deformability
materials, with joints made by welding or brazing. | 2.5 | 9.0 |
| Ductwork, including in-line components, constructed of high- or limited-
deformability materials with joints made by means other than welding or
brazing. | 2.5 | 6.0 |
| Ductwork, including in-line components, constructed of low-deformability
materials, such as cast iron, glass, and non-ductile plastics. | 2.5 | 3.0 |
| Electrical conduit, bus ducts, rigidly mounted cable trays, and plumbing. | 1.0 | 2.5 |
| Manufacturing or process conveyors (non-personnel). | 2.5 | 3.0 |
| Suspended cable trays. | 2.5 | 6.0 |
> *a* A lower value for αc is permitted where justified by detailed dynamic analysis. The value for αc shall not be less than 1.0. The value of αc equal to 1.0 is for rigid components and rigidly attached components. The value of αc equal to 2.5 is for flexible components and flexibly attached components.
* *b* Components mounted on vibration isolators shall have a bumper restraint or snubber in each horizontal direction. The design force shall be taken as 2 *Fc* if the nominal clearance (air gap) between the equipment support frame and restraint is greater than 6 mm. If the nominal clearance specified on the construction documents is not greater than 6 mm, the design force may be taken as *Fc* .
#### 2.5.16.2 Equivalent static analysis
The equivalent static analysis procedure is permitted to be used for design of a seismically isolated structure provided that:
* (1) The structure is located on Site Class SA, SB, SC, SD or SE site;
* (2) The structure above the isolation interface is not more than four stories or 20 m in height
* (3) Effective period of the isolated structure at the maximum displacement, TM, is less than or equal to 3.0 sec.
* (4) The effective period of the isolated structure at the design displacement, TD, is greater than three times the elastic, fixed-base period of the structure above the isolation system as determined in Sec. 2.5.7.2
* (5) The structure above the isolation system is of regular configuration; and
* (6) The isolation system meets all of the following criteria:
* (a) The effective stiffness of the isolation system at the design displacement is greater than one third of the effective stiffness at 20 percent of the design displacement,
* (b) The isolation system is capable of producing a restoring force as specified in Sec. 2.5.16.1,
* (c) The isolation system does not limit maximum considered earthquake displacement to less than the total maximum displacement.
Where the equivalent lateral force procedure is used to design seismically isolated structures, the requirements of this Section shall apply.
##### 2.5.16.2.1
Displacement of isolation system: The isolation system shall be designed and constructed to withstand minimum lateral earthquake displacements that act in the direction of each of the main horizontal axes of the structure and such displacements shall be calculated as follows:
$$
D_D = \frac{S_ag}{4\pi^2}\left(\frac{T_D^2}{B_D}\right) \tag{6.2.62}
$$
Where,
* *Sa* = Design spectral acceleration (in units of *g* ), calculated using Eq. 6.2.34 for period *TD* and assuming \_R=1, I=1 η *=1* (Sec 2.5.4.3) for the design basis earthquake (DBE).
* *g* = acceleration due to gravity
* *BD* = damping coefficient related to the effective damping βD of the isolation system at the design displacement, as set forth in Table 6.2.24.
* *TD* = effective period of seismically isolated structure at the design displacement in the direction under consideration, as prescribed by Eq. 6.2.63:
$$
T_D = 2\pi\sqrt{\frac{W}{k_{D min}g}} \tag{6.2.63}
$$
Where,
* *W* = seismic weight above the isolation interface
*kDmin* = minimum effective stiffness of the isolation system at the design displacement in the horizontal direction under consideration.
**Table 6.2.24: Damping Coefficient,** ***BD* or** ***BM***
| **Effective Damping,\*\*\*\*\_βD or βM \_*****a, b******(%)*** | ***BD or BM*** |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------- |
| ≤ 2 | 0.8 |
| 5 | 1.0 |
| 10 | 1.2 |
| 20 | 1.5 |
| 30 | 1.7 |
| 40 | 1.9 |
| ≥ 50 | 2.0 |
| *a* The damping coefficient shall be based on the effective damping of the isolation system *b* The damping coefficient shall be based on linear interpolation for effective damping values other than those given. | |
The maximum displacement of the isolation system, DM, in the most critical direction of horizontal response shall be calculated in accordance with the following formula:
$$
D_M = \frac{S_{aM}g}{4\pi^2}\left(\frac{T_M^2}{B_M}\right) \tag{6.2.64}
$$
Where:
* *SaM* = Maximum spectral acceleration (in units of *g* ), calculated using Eq. 6.2.34 for period *TD* and assuming \_R=1, I=1 η *=1* (Sec 2.5.4.3) for the maximum considered earthquake (MCE).
* *BM* = numerical coefficient related to the effective damping βM of the isolation system at the maximum displacement, as set forth in Table 6.2.24.
* *TM* = effective period of seismic-isolated structure at the maximum displacement in the direction under consideration as prescribed by:
$$
T_M = 2\pi\sqrt{\frac{W}{k_{M min}g}} \tag{6.2.65}
$$
Where,
$k_{Mmin}$ = minimum effective stiffness of the isolation system at the maximum displacement in the horizontal direction under consideration.
The total design displacement, DTD, and the total maximum displacement, DTM, of elements of the isolation system shall include additional displacement due to inherent and accidental torsion calculated considering the spatial distribution of the lateral stiffness of the isolation system and the most disadvantageous location of eccentric mass.
##### 2.5.16.2.2
Lateral seismic forces: The structure above the isolation system shall be designed and constructed to withstand a minimum lateral force, Vs, using all of the appropriate provisions for a non-isolated structure. The importance factor for all isolated structures shall be considered as 1.0, also the response reduction factor *RI* considered here (for computing design seismic forces) is in the range of 1.0 to 2.0. Vs shall be determined in accordance with Eq. 6.2.66 as follows:
$$
V_s = \frac{k_{D max}D_D}{R_I} \tag{6.2.66}
$$
Where,
* $k_{Dmax}$ = maximum effective stiffness of the isolation system at the design displacement in the horizontal direction under consideration.
* $D_D$ = design displacement at the center of rigidity of the isolation system in the direction under consideration as prescribed by Eq. 6.2.62.
* $R_I$ = response reduction factor related to the type of seismic-force-resisting system above the isolation system. RI shall be based on the type of seismic-force-resisting system used for the structure above the isolation
* system and shall be taken as the lesser of $\frac{3}{8}R$ (Table 6.2.19) or 2.0, but
* need not be taken less than 1.0.
In no case shall Vs be taken less than the following:
* (1) The lateral force required by Sec 2.5.7 for a fixed-base structure of the same weight, W, and a period equal to the isolated period, TD;
* (2) The base shear corresponding to the factored design wind load; and
* (3) The lateral force required to fully activate the isolation system (e.g., the yield level of a softening system, the ultimate capacity of a sacrificial wind-restraint system, or the break-away friction level of a sliding system) multiplied by 1.5.
The isolation system, the foundation, and all structural elements below the isolation system shall be designed and constructed to withstand a minimum lateral force, $V_b$ using all of the appropriate provisions for a non-isolated structure. $V_b$ shall be determined in accordance with Eq. 6.2.67 as follows:
$$
V_b = k_{Dmax}D_D \tag{6.2.67}
$$
In all cases, $V_b$ shall not be taken less than the maximum force in the isolation system at any displacement up to and including the design displacement.
##### 2.5.16.2.3
Vertical distribution of lateral forces: The total lateral force shall be distributed over the height of the structure above the isolation interface in accordance with Eq. 6.2.68 as follows:
$$
F_x = V_s\frac{w_xh_x}{\sum\limits_{i=1}^{n} w_ih_i} \tag{6.2.68}
$$
Where:
* $F_x$ = Total seismic lateral design force on elements above the isolation system.
* $h_i$, $h_x$ = Height above the base, to Level i or Level x, respectively.
* $w_i$, $w_x$ = Portion of W that is located at or assigned to Level i or Level x, respectively.
At each Level x the force, $F_x$ shall be applied over the area of the structure in accordance with the distribution of mass at the level. Stresses in each structural element shall be determined by applying the lateral forces, $F_x$ at all levels above the base to an analytical model.
##### 2.5.16.2.4
Storey drift: The storey drift shall be calculated as in Sec 2.5.7.7 except that Cd for the isolated structure shall be taken equal to RI and importance factor equal to 1.0. The maximum storey drift of the structure above the isolation system shall not exceed 0.015hsx.
#### 2.5.16.3 Dynamic analysis
Response spectrum analysis may be conducted if the behavior of the isolation system can be considered as equivalent linear. Otherwise, non-linear time history analysis shall be used where the true non-linear behaviour of the isolation system can be modeled. The mathematical models of the isolated structure including the isolation system shall be along guidelines given in Sections 2.5.9.1 and 2.5.11.1, and other requirements given in Sec 2.5.16.
The isolation system shall be modeled using deformational characteristics developed and verified by testing. The structure model shall account for: (i) spatial distribution of isolator units; (ii) consideration of translation in both horizontal directions, and torsion of the structure above the isolation interface considering the most disadvantageous location of eccentric mass; (iii) overturning/uplift forces on individual isolator units; and (iv) effects of vertical load, bilateral load, and the rate of loading if the force-deflection properties of the isolation system are dependent on such attributes.
A linear elastic model of the isolated structure (above isolation system) may be used provided that: (i) stiffness properties assumed for the nonlinear components of the isolation system are based on the maximum effective stiffness of the isolation system, and (ii) all elements of the seismic-force-resisting system of the structure above the isolation system behave linearly.
##### 2.5.16.3.1
Response Spectrum Analysis: Response spectrum analysis shall be performed using a modal damping value for the fundamental mode in the direction of interest not greater than the effective damping of the isolation system or 30 percent of critical, whichever is less. Modal damping values for higher modes shall be selected consistent with those that would be appropriate for response spectrum analysis of the structure above the isolation system assuming a fixed base.
Response spectrum analysis used to determine the total design displacement and the total maximum displacement shall include simultaneous excitation of the model by 100 percent of the ground motion in the critical direction and 30 percent of the ground motion in the perpendicular, horizontal direction. The design basis earthquake shall be used for the design displacement, while the maximum considered earthquake shall be used for the maximum displacement. The maximum displacement of the isolation system shall be calculated as the vectorial sum of the two orthogonal displacements.
For the design displacement, structures that do not require site-specific ground motion evaluation, shall be analyzed using the design acceleration response spectrum in accordance with Sec 2.5.4.3. The maximum design spectrum to be used for the maximum considered earthquake shall not be less than 1.5 times the design acceleration response spectrum.
The response spectrum procedure is based on an equivalent linear model, where the effective stiffness and effective damping is a function of the displacement, this formulation is thus an iterative process. The effective stiffness must be estimated, based on assumed displacement, and then adjusted till obtained displacement agree with assumed displacement.
The design shear at any story shall not be less than the story shear resulting from application of the story forces calculated using Eq. 6.2.68 with a value of equal to the base shear obtained from the response spectrum analysis in the direction of interest.
##### 2.5.16.3.2
Nonlinear Time History Analysis: Where a time history analysis procedure is performed, not fewer than three appropriate ground motions shall be used in the analysis as described below.
Ground motions shall consist of pairs of appropriate horizontal ground motion acceleration components that shall be selected and scaled from individual recorded events. Appropriate ground motions shall be selected from events having magnitudes, fault distance, and source mechanisms that are consistent with those that control the maximum considered earthquake. If required number of recorded ground motion pairs are not available, appropriate simulated ground motion pairs shall be used to make up the total number required. For each pair of horizontal groundmotion components, a square root of the sum of the squares (SRSS) spectrum shall be constructed by taking the SRSS of the 5 percent damped response spectra for the scaled components (where an identical scale factor is applied to both components of a pair). Each pair of motions shall be scaled such that for each period between 0.5TD and 1.25TM (where TD and TM are defined in Sec 2.5.16.2.1) the average of the SRSS spectra from all horizontal component pairs does not fall below 1.3 times the corresponding ordinate of the design response spectrum (Sec 2.5.16.4), by more than 10 percent.
Each pair of ground motion components shall be applied simultaneously to the model considering the most disadvantageous location of eccentric mass. The maximum displacement of the isolation system shall be calculated from the vectorial sum of the two orthogonal displacements at each time step.
The parameters of interest shall be calculated for each ground motion used for the time history analysis. If at least seven ground motions are used for the time history analysis, the average value of the response parameter of interest is permitted to be used for design. If fewer than seven ground motions are analyzed, the maximum value of the response parameter of interest shall be used for design.
##### 2.5.16.3.3
Storey drift: Maximum story drift corresponding to the design lateral force including displacement due to vertical deformation of the isolation system shall not exceed the following limits:
1. The maximum story drift of the structure above the isolation system calculated by response spectrum analysis shall not exceed 0.015 *ℎ* .
2. The maximum story drift of the structure above the isolation system calculated by nonlinear time history analysis shall not exceed 0.020 *ℎ* .
The storey drift shall be calculated as in Sec 2.5.7.7 except that *Cd* for the isolated structure shall be taken equal to *RI* and importance factor equal to 1.0.
#### 2.5.16.4 Testing
The deformation characteristics and damping values of the isolation system used in the design and analysis of seismically isolated structures shall be based on test results of isolator units. The tests are for establishing and validating the design properties of the isolation system and shall not be considered as satisfying the manufacturing quality control tests.
The following sequence of tests shall be performed on isolator units for the prescribed number of cycles at a vertical load equal to the average dead load plus one-half the effects due to live load on all isolator units of a common type and size:
* (1) Twenty fully reversed cycles of loading at a lateral force corresponding to the wind design force.
* (2) Three fully reversed cycles of loading at each of the following increments of the total design displacement-0.25DD, 0.5DD, 1.0DD, and 1.0DM where DD and DM are as determined in Sec 2.5.16.2.1.
* (3) Three fully reversed cycles of loading at the total maximum displacement, 1.0DTM.
* (4) Not less than ten fully reversed cycles of loading at 1.0 times the total design displacement, 1.0DTD.
For each cycle of each test, the force-deflection and hysteretic behavior of each isolator unit shall be recorded. The effective stiffness is obtained as the secant value of stiffness at design displacement while the effective damping is determined from the area of hysteretic loop at the design displacement.
#### 2.5.16.5 Design review
A design review of the isolation system and related test programs shall be performed by an independent team of design professionals experienced in seismic analysis methods and the application of seismic isolation. Isolation system design review shall include, but need not be limited to, the following:
* (1) Review of site-specific seismic criteria including the development of sitespecific spectra and ground motion time histories and all other design criteria developed specifically for the project;
* (2) Review of the preliminary design including the determination of the total design displacement of the isolation system and the lateral force design level;
* (3) Overview and observation of prototype (isolator unit) testing
* (4) Review of the final design of the entire structural system and all supporting analyses; and
* (5) Review of the isolation system quality control testing program.
### **2.5.17 Buildings with Soft Storey**
Buildings with possible soft storey action at ground level for providing open parking spaces belong to structures with major vertical irregularity \[Figure 6.2.28(a)]. Special arrangement is needed to increase the lateral strength and stiffness of the soft/open storey. The following two approaches may be considered:
* (1) Dynamic analysis of such building may be carried out incorporating the strength and stiffness of infill walls and inelastic deformations in the members, particularly those in the soft storey, and the members designed accordingly.
* (2) Alternatively, when system overstrength factor, Ωo, is not included in determining seismic load effects, the following design criteria are to be adopted after carrying out the earthquake analysis, neglecting the effect of infill walls in other storeys. Structural elements (e.g columns and beams) of the soft storey are to be designed for 2.5 times the storey shears and moments calculated under seismic loads neglecting effect of infill walls. Shear walls placed symmetrically in both directions of the building as far away from the centre of the building as feasible are to be designed exclusively for 1.5 times the lateral shear force calculated before.
### **2.5.18 Non-Building Structures**
Calculation of seismic design forces on non-building structures (e.g. chimney, selfsupported overhead water/fluid tank, silo, trussed tower, storage tank, cooling tower, monument and other structures not covered in Sec 2.5) shall be in accordance with "Chapter 15: Seismic Design Requirements for Non-Building Structures, Minimum Design Loads for Buildings and Other Structures, ASCE Standard ASCE/SEI 7-05" complying with the requirements of Sec 2.5 of this Code.
## **2.6 Miscellaneous Loads**
### **2.6.1 General**
The procedures and limitations for the determination of selected miscellaneous loads are provided in this Section. Loads that are not specified in this Section or elsewhere in this Chapter, may be determined based on information from reliable references or specialist advice may be sought.
### **2.6.2 Rain Loads**
Rain loads shall be determined in accordance with the following provisions.
#### 2.6.2.1 Blocked drains
Each portion of a roof shall be designed to sustain the load from all rainwater that could be accumulated on it if the primary drainage system for that portion is undersized or blocked. Ponding instability shall be considered in this situation.
#### 2.6.2.2 Controlled drainage
Roofs equipped with controlled drainage provisions shall be designed to sustain all rainwater loads on them to the elevation of the secondary drainage system plus 0.25 kN/m2 . Ponding instability shall be considered in this situation.
### **2.6.3 Loads Due to Flood and Surge**
For the determination of flood and surge loads on a structural member, consideration shall be given to both hydrostatic and hydrodynamic effects. Required loading shall be determined in accordance with the established principles of mechanics based on site specific criteria and in compliance with the following provisions of this Section. For essential facilities like cyclone and flood shelters and for hazardous facilities specified in Table 6.1.1, values of maximum flood elevation, surge height, wind velocities etc., required for the determination of flood and surge load, shall be taken corresponding to 100-year return period. For structures other than essential and hazardous facilities, these values shall be based on 50-year return period.
#### 2.6.3.1 Flood loads on structures at inland areas
For structures sited at inland areas subject to flood, loads due to flood shall be determined considering hydrostatic effects which shall be calculated based on the flood elevation of 50-year return period. For river-side structures such as that under Exposure C specified in Sec 2.4.6.3, hydrodynamic forces, arising due to approaching wind-generated waves shall also be determined in addition to the hydrostatic load on them. In this case, the amplitude of such wind-induced water waves shall be obtained from site-specific data.
#### 2.6.3.2 Flood and surge loads on structures at coastal areas
Coastal area of Bangladesh has been delineated as Risk Area (RA) and High Risk Area (HRA) based on the possible extend of the inland intrusion of the cyclone storm surge as shown in Figure 6.2.30. To be classified as coastal RISK AREA, the principal source of flooding must be sea tides, storm surge, and not riverine flood. The RA extends from the coast line to an inland limit up to which surge water can reach. The HRA includes a strip of land within the RA. It extends from the coast line up to the limit where the depth of storm surge inundation may exceed 1m.Entire area of the off-shore islands except the Maheshkhali area is included in the HRA. A part of Maheshkhali is covered by hills and therefore free from inundation. However, the western and northern parts of Maheshkhali are of low elevation and risk inundation. For structures sited in coastal areas (Risk Areas), the hydrostatic and hydrodynamic loads shall be determined as follows:
##### 2.6.3.2.1 Hydrostatic Loads
The hydrostatic loads on structural elements and foundations shall be determined based on the maximum static height of water, *Hm* , produced by floods or surges as given by the relation:
$$
H_m = max(h_s, h_f) \tag{6.2.69}
$$
$$
h_f = y_T - y_g \tag{6.2.70}
$$
Where,
* $h_s$ = Maximum surge height as specified in (i) below.
* $y_T$ = Elevation of the extreme surface water level corresponding to a *T* -year return period specified in (ii) below, meters
* $y_g$ = Elevation of ground level at site, meters.
![Coastal risk areas (RA) and high risk areas (HRA) of Bangladesh]()
Figure 6.2.30 Coastal risk areas (RA) and high risk areas (HRA) of Bangladesh
* (i) Maximum Surge Height, *hs* : The maximum surge height, *hs* , associated with cyclones, shall be that corresponding to a 50-year or a 100-year return period as may be applicable, based on site specific analysis. In the absence of a more rigorous site specific analysis, the following relation may be used:
$$
h_s = h_T - (x-1)k \tag{6.2.71}
$$
Where, *hT* = design surge height corresponding to a return period of *T* -years at sea coast, in metres, given in Table 6.2.25.
* *x* = distance of the structure site measured from the spring tide highwater limit on the sea coast, in km; *x* = 1, if *x* \<1.
* *k* = rate of decrease in surge height in meter/km; the value of *k* may be taken as 0.5 for Chittagong-Cox's Bazar-Teknaf coast and as 0.33 for other coastal areas.
* (ii) Extreme Surface Water Level, $y_T$: The elevation of the extreme surface water level, $y_T$ for a site, which may not be associated with a cyclonic storm surge, shall be that obtained from a site specific analysis corresponding to a 50-year or a 100-year return period. Values of $y_T$ are given in Table 6.2.26 for selected coastal locations which may be used in the absence of any site specific data.
Hydrostatic loads caused by a depth of water to the level of the $H_m$ shall be applied over all surfaces involved, both above and below ground level, except that for surfaces exposed to free water, the design depth $H_m$ shall be increased by 0.30 m. Reduced uplift and lateral loads on surfaces of enclosed spaces below the $H_m$ shall apply only if provision is made for entry and exit of floodwater.
**Table 6.2.25: Design Surge Heights at the Sea Coast,** ***hT***\*\*\*\*\*
| **Coastal Region** | **Surge Height at th**
**(m)** | **e Sea Coast,\*\*\*\**hT*** |
| ---------------------------------------------- | ----------------------------------- | ----------------------------------- |
| | ***T*= 50-year****(1)** | ***T*= 100-year****(2)** |
| Teknaf to Cox's Bazar | 4.5 | 5.8 |
| Chakaria to Anwara, and Maheshkhali-Kutubdia | 7.1 | 8.6 |
| Islands | | |
| Chittagong to Noakhali | 7.9 | 9.6 |
| Sandwip, Hatiya and all islands in this region | 7.9 | 9.6 |
| Bhola to Barguna | 6.2 | 7.7 |
| Sarankhola to Shyamnagar | 5.3 | 6.4 |
| **Notes:** | | |
* Values prepared from information obtained from Annex-D3, MCSP.
* (1) These values may be used in the absence of site specific data for structures other than essential facilities listed in Table 6.1.1.
* (2) These values may be used in the absence of site specific data for essential facilities listed in Table 6.1.1.
**Table 6.2.26: Extreme Surface Water Levels above PWD Datum,** ***yT***\*\*\*\*\* **at Coastal Areas during Monsoon**
| **Coas** | **tal Area** | \*\**yT* \*\* | **(m)** |
| ---------------------------- | ------------ | ---------------------------------- | ----------------------------------- |
| **Location** | **Thana** | **T = 50 years****(1)** | **T = 100 years****(2)** |
| Teknaf | Teknaf | 2.33 | 2.44 |
| Cox's Bazar | Cox's Bazar | 3.84 | 3.88 |
| Shaflapur | Moheshkhali | 4.67 | 4.87 |
| Lemsikhali | Kutubdia | 4.95 | 5.19 |
| Banigram | Patiya | 5.05 | 5.24 |
| Chittagong | Bandar | 4.72 | 4.88 |
| Patenga | Bandar | 4.08 | 4.16 |
| Sonapur | Sonagazi | 7.02 | 7.11 |
| Sandwip | Sandwip | 6.09 | 6.2 |
| Companyganj | Companyganj | 7.53 | 7.94 |
| Hatiya | Hatiya | 5.55 | 5.76 |
| Daulatkhan | Daulatkhan | 4.62 | 4.72 |
| Dashmina | Dashmina | 3.60 | 3.73 |
| Galachipa | Galachipa | 3.79 | 3.92 |
| Patuakhali | Patuakhali | 2.87 | 3.03 |
| Khepupara | Kalapara | 2.93 | 3.02 |
| Bamna | Bamna | 3.32 | 3.37 |
| Patharghata | Patharghata | 3.65 | 3.84 |
| Raenda | Sarankhola | 3.66 | 3.75 |
| Chardouni | Patharghata | 4.41 | 4.66 |
| Mongla | Mongla port | 3.23 | 3.36 |
| Kobodak (river
estuary) | Shyamnagar | 3.51 | 3.87 |
| Kaikhali | Shyamnagar | 3.94 | 4.12 |
| **Notes:** | | | |
* Values prepared from information obtained from Annex -D3, MCSP
* (1) These values may be used in the absence of site specific data for structures in Structure Occupancy Category IV listed Table 6.1.1.
* (2) These values may be used in the absence of site specific data for structures in Structure Occupancy Categories I, II and III listed in Table 6.1.1.
##### 2.6.3.2.2 Hydrodynamic loads
The hydrodynamic load applied on a structural element due to wind-induced local waves of water, shall be determined by a rational analysis using an established method of fluid mechanics and based on site specific data. In the absence of a sitespecific data the amplitude of the local wave, to be used in the rational analysis, shall be taken as $h_w = \dfrac{h_s}{4} \geq 1$ m, where, *hs* is given in Sec 2.6.3.2.1. Such forces shall be calculated based on 50-year or 100-year return period of flood or surge. The corresponding wind velocities shall be 80 m/s or 90 m/s (3-sec gust) respectively.
Exception:
Where water velocities do not exceed 3.0 m/s, dynamic effects of moving water shall be permitted to be converted into equivalent hydrostatic loads by increasing *Hm* for design purposes by an equivalent surcharge depth, *dh* , on the headwater side and above the ground level only, equal to
$$
d_h = \frac{aV^2}{2g} \tag{6.2.72}
$$
Where,
*V* = average velocity of water in m/s
*g* = acceleration due to gravity, 9.81 m/s2
*a* = coefficient of drag or shape factor (not less than 1.25)
In absence of more authentic site specific data, the velocity of water, *V* , may be estimated such that $d_s \leq V \leq \sqrt{gd_s}$ where *g* is the acceleration due to gravity and *ds* is defined in Sec 2.6.3.4. Selection of the correct value of drag-coefficient *a* in Eq. 6.2.72 will depend upon the shape and roughness of the object exposed to flood flow, as well as the flow condition. As a general rule, the smoother and more streamlined the object, the lower the drag coefficient (shape factor). Drag coefficients for elements common in buildings and structures (round or square piles, columns, and rectangular shapes) will range from approximately 1.0 to 2.0, depending upon flow
conditions. However, given the uncertainty surrounding flow conditions at a particular site, it is recommended that a minimum value of 1.25 be used. Fluid mechanics texts should be consulted for more information on when to apply drag coefficients above 1.25.
The equivalent surcharge depth, *dh* , shall be added to the design depth *Hm* and the resultant hydrostatic pressures applied to, and uniformly distributed across, the vertical projected area of the building or structure that is perpendicular to the flow. Surfaces parallel to the flow or surfaces wetted by the tail water shall be subject to the hydrostatic pressures for depths to the *Hm* only.
#### 2.6.3.3 Breakaway walls
Walls and partitions required to break away, including their connections to the structure, shall be designed for the largest of the following loads acting perpendicular to the plane of the wall:
* (i) The wind load specified in Sec. 2.4.
* (ii) The earthquake load specified in Sec. 2.5.
* (iii) 0.50 kN/m2 pressure.
The loading at which breakaway walls are intended to collapse shall not exceed 1.0 kN/m2 unless the design meets the following conditions:
* (i) Breakaway wall collapse is designed to result from a flood load less than that which occurs during the base flood.
* (ii) The supporting foundation and the elevated portion of the building shall be designed against collapse, permanent lateral displacement, and other structural damage due to the effects of flood loads in combination with other loads as specified elsewhere in this Chapter.
#### 2.6.3.4 Wave loads
Wave loads shall be determined by one of the following three methods: (1) by using the analytical procedures outlined in this Section, (2) by more advanced numerical modeling procedures, or (3) by laboratory test procedures (physical modeling).
Wave loads are those loads that result from water waves propagating over the water surface and striking a building or other structure. Design and construction of buildings and other structures subject to wave loads shall account for the following loads: a) waves breaking on any portion of the building or structure; b) uplift forces caused by shoaling waves beneath a building or structure, or portion thereof; c) wave runup striking any portion of the building or structure; d) wave-induced drag and
inertia forces; and e) wave-induced scour at the base of a building or structure, or its foundation. Nonbreaking and broken wave loads shall be calculated using the procedures described in Sections 2.6.3.2.1 and 2.6.3.2.2 that show how to calculate hydrostatic and hydrodynamic loads.
Breaking wave loads shall be calculated using the procedures described in Sections 2.6.3.4.1 to 2.6.3.4.4. Breaking wave heights used in the procedures described in these Sections shall be calculated for using Equations 6.2.73 and 6.2.74.
$$
H_b = 0.78d_s \tag{6.2.73}
$$
Where,
$H_b$ = breaking wave height in meter.
$d_s$ = local still water depth in meter.
The local still water depth shall be calculated using Eq. 6.2.74 unless more advanced procedures or laboratory tests permitted by this Section are used.
$$
d_s = 0.65H_m \tag{6.2.74}
$$
##### 2.6.3.4.1 Breaking wave loads on vertical pilings and columns
The net force resulting from a breaking wave acting on a rigid vertical pile or column shall be assumed to act at the still water elevation and shall be calculated by the following:
$$
F_D = 0.5\gamma_wC_DDH_b^2 \tag{6.2.75}
$$
Where,
* $F_D$ = net wave force, in kN.
* $\gamma_w$ = unit weight of water, in kN/m3 = 9.80 kN/m3 for fresh water and 10.05 kN/m3 or salt water.
* $C_D$ = coefficient of drag for breaking waves, = 1.75 for round piles or columns, and = 2.25 for square piles or columns.
* $D$ = pile or column diameter, in meter for circular sections, or for a square pile or column, 1.4 times the width of the pile or column in meter.
* $H_b$ = breaking wave height, in meter.
##### 2.6.3.4.2 Breaking wave loads on vertical walls
Maximum pressures and net forces resulting from a normally incident breaking wave (depth-limited in size, with $H_b = 0.78d_s$ acting on a rigid vertical wall shall be calculated by the following:
$$
P_{max} = C_p\gamma_wd_s + 1.2\gamma_wd_s \tag{6.2.76}
$$
$$
F_t = 1.1C_p\gamma_wd_s^2 + 2.4\gamma_wd_s^2 \tag{6.2.77}
$$
Where,
* $P_{max}$ = maximum combined dynamic $(C_p\gamma_wd_s)$ and static $(1.2\gamma_wd_s)$ wave pressures, also referred to as shock pressures in kN/m2 .
* $F_t$ = net breaking wave force per unit length of structure, also referred to as shock, impulse, or wave impact force in kN/m, acting near the still water elevation.
* $C_p$ = dynamic pressure coefficient. It shall be taken as 1.6, 2.8, 3.2 or 3.5 for building occupancy categories I, II, III or IV respectively.
* $\gamma_w$ = unit weight of water, in kN/m3 = 9.80 kN/m3 for fresh water and 10.05 kN/m3 for salt water
* $d_s$ = still water depth in meter at base of building or other structure where the wave breaks.
This procedure assumes the vertical wall causes a reflected or standing wave against the water ward side of the wall with the crest of the wave at a height of 1.2 above the still water level. Thus, the dynamic static and total pressure distributions against the wall are as shown in Figure 6.2.31.
This procedure also assumes the space behind the vertical wall is dry, with no fluid balancing the static component of the wave force on the outside of the wall. If free water exists behind the wall, a portion of the hydrostatic component of the wave pressure and force disappears (Figure 6.2.32) and the net force shall be computed by Eq. 6.2.78 (the maximum combined wave pressure is still computed with Eq. 6.2.76).
$$
F_t = 1.1C_p\gamma_wd_s^2 + 1.9\gamma_wd_s^2 \tag{6.2.78}
$$
Where,
* $F_t$ = net breaking wave force per unit length of structure, also referred to as shock, impulse, or wave impact force in kN/m, acting near the still water elevation.
* $C_p$ = dynamic pressure coefficient. It shall be taken as 1.6, 2.8, 3.2 or 3.5 for building occupancy categories I, II, III or IV respectively.
* $\gamma_w$ = unit weight of water, in kN/m3 = 9.80 kN/m3 for fresh water and 10.05 kN/m3 for salt water
* $d_s$ = still water depth in meter at base of building or other structure where the wave breaks.
##### 2.6.3.4.3 Breaking wave loads on nonvertical walls
Breaking wave forces given by Equations 6.2.77 and 6.2.78 shall be modified in instances where the walls or surfaces upon which the breaking waves act are nonvertical. The horizontal component of breaking wave force shall be given by
$$
F_{nv} = F_t\sin^2\alpha \tag{6.2.79}
$$
Where,
* $F_{nv}$ = horizontal component of breaking wave force in kN/m.
* $F_t$ = net breaking wave force acting on a vertical surface in kN/m.
* $\alpha$ = vertical angle between nonvertical surface and the horizontal.
##### 2.6.3.4.4 Breaking Wave Loads from Obliquely Incident Waves.
Breaking wave forces given by Equations 6.2.77 and 6.2.78 shall be modified in instances where waves are obliquely incident. Breaking wave forces from nonnormally incident waves shall be given by
$$
F_{oi} = F_t\sin^2\alpha \tag{6.2.80}
$$
Where,
* $F_{oi}$ = horizontal component of obliquely incident breaking wave force in kN/m.
* $F_t$ = net breaking wave force (normally incident waves) acting on a vertical surface in kN/m.
* $\alpha$ = horizontal angle between the direction of wave approach and the vertical surface.
#### 2.6.3.5 Impact loads
Impact loads are those that result from debris, ice, and any object transported by floodwaters striking against buildings and structures, or parts thereof. Impact loads shall be determined using a rational approach as concentrated loads acting horizontally at the most critical location at or below $H_m$ (Eq. 6.2.69). Eq. 6.2.81 provides a rational approach for calculating the magnitude of the impact load.
$$
F = \frac{\pi WV_bC_IC_OC_DC_BR_{max}}{2g\Delta t} \tag{6.2.81}
$$
Where,
* $F$ = impact force in N
* $W$ = debris weight in N, to be taken equal to 4448 N unless more specific data is available.
* $V_b$ = velocity of the debris, m/s, assumed equal to the velocity of water *V* defined in Sec. 2.6.3.2.2.
* $g$ = acceleration due to gravity, 9.81 m/s2
$\Delta t$ = duration of impact, which may be taken as 0.03 second
* $C_I$ = importance co-efficient = 0.6, 1.0, 1.2 or 1.3 for building occupancy categories I, II, III or IV respectively
* $C_O$ = orientation co-efficient = 0.8
* $C_D$ = depth co-efficient, to be taken equal to 0.0 for water depth 0.3m or less and equal to 1.0 for water depth 1.5m or more. Linear interpolation shall be made for intermediate water depth values.
* $C_B$ = blockage co-efficient, to be taken equal to 0.0 for upstream flow channel width 1.5m or less and equal to 1.0 for upstream flow channel width 9.1 m or more. Linear interpolation shall be made for intermediate values of upstream flow channel width. The upstream shall extend 30.0 m from the building.
* $R_{max}$ = maximum response ratio for impulsive load (half sine wave type) to be obtained from Table 6.2.27.
### **2.6.4 Temperature Effects**
Temperature effects, if significant, shall be considered in the design of structures or components thereof in accordance with the provision of this Section. In determining the temperature effects on a structure, the following provisions shall be considered:
* (a) The temperatures indicated, shall be the air temperature in the shade. The range of the variation in temperature for a building site shall be taken into consideration.
* (b) Effects of the variation of temperature within the material of a structural element shall be accounted for by one of the following methods.
* (i) Relieve the stresses by providing adequate numbers of expansion or contraction joints,
* (ii) Design the structural element to sustain additional stresses due to temperature effects.
* (c) when the method b(ii) above is considered to be applicable, the structural analysis shall take into account the following :
* (i) The variation in temperature within the material of the structural element, exposure condition of the element and the rate at which the material absorb or radiate heat.
* (ii) The warping or any other distortion caused due to temperature changes and temperature gradient in the structural element.
* (d) When it can be demonstrated by established principle of mechanics or by any other means that neglecting some or all of the effects of temperature, does not affect the safety and serviceability of the structure, the temperature effect can be considered insignificant and need not be considered in design.
![Normally incident breaking wave pressures against a vertical wall (space behind vertical wall is dry)]()
**Figure 6.2.31 Normally incident breaking wave pressures against a vertical wall (space behind vertical wall is dry)**
![Normally incident breaking wave pressures against a vertical wall (still water level equal on both sides of wall)]()
**Figure 6.2.32 Normally incident breaking wave pressures against a vertical wall (still water level equal on both sides of wall)**
**Table 6.2.27: Values of response ratio,** $R_{max}$ **, for impulsive loads**
| Ratio of impulse duration | @' | Ratio of impulse duration | @' |
| ------------------------- | --- | ------------------------- | --- |
| (∆±) to natural period | | (∆±) to natural period | |
| (Sec. 2.5) of structure | | (Sec. 2.5) of structure | |
| 0 | 0 | 0.8 | 1.8 |
| 0.1 | 0.4 | 0.9 | 1.8 |
| 0.2 | 0.8 | 1 | 1.7 |
| 0.3 | 1.1 | 1.1 | 1.7 |
| 0.4 | 1.4 | 1.2 | 1.6 |
| 0.5 | 1.5 | 1.3 | 1.6 |
| 0.6 | 1.7 | ≥1.4 | 1.5 |
| 0.7 | 1.8 | | |
### **2.6.5 Soil and Hydrostatic Pressure**
For structures or portions thereof, lying below ground level, loads due to soil and hydrostatic pressure shall be determined in accordance with the provisions of this Section and applied in addition to all other applicable loads.
#### 2.6.5.1 Pressure on basement wall:
In the design of basement walls and similar vertical or nearly vertical structures below grade, provision shall be made for the lateral pressure of adjacent soil. Allowance shall be made for possible surcharge due to fixed or moving loads. When a portion or the whole of the adjacent soil is below the surrounding water table, computations shall be based on the submerged unit weight of soil, plus full hydrostatic pressure.
#### 2.6.5.2 Uplift on floors:
In the design of basement floors and similar horizontal or nearly horizontal construction below grade, the upward pressure of water, if any, shall be taken as the full hydrostatic pressure applied over the entire area. The hydrostatic head shall be measured from the underside of the construction.
### **2.6.6 Loads due to Explosions**
Loads on buildings or portions thereof, shall be assessed in accordance with the provisions of this Section.
#### 2.6.6.1 Explosion effects in closed rooms
* (a) Determination of Loads and Response: Internal overpressure developed from an internal explosion such as that due to leaks in gas pipes, evaporation of volatile liquids, internal dust explosion etc., in rooms of sizes comparable to residential rooms and with ventilation areas consisting of window glass breaking at a pressure of 4 kN/m2 (3-4 mm machine made glass) may be calculated from the following method :
* (i) The overpressure, X; provided in Figure 6.2.33(a) shall be assumed to depend on a factor ;/=, where, ; is the total window area in m2 and = is the volume in m3 of the room considered,
* (ii) The internal pressure shall be assumed to act simultaneously upon all walls and floors in one closed room, and
* (iii) The action X; obtained from Figure 6.2.33(a) may be taken as static action.
When a time dependent response is required, an impulsive force function similar to that shown in Figure 6.2.33(b) shall be used in a dynamic analysis, where *t* 1 is the time from the start of combustion until maximum pressure is reached and *t* 2 is the time from maximum pressure to the end of combustion. For *t* 1 and *t* 2 the most unfavourable values shall be chosen in relation to the dynamic properties of the structures. However, the values shall be chosen within the intervals as given in Figure 6.2.33(b).
The pressure may be applied solely in one room or in more than one room at the same time. In the latter case, all rooms are incorporated in the volume *v* . Only windows or other similarly weak and light weight structural elements may be taken as ventilation areas even though certain limited structural parts break at pressures less than *qo.*
* (b) Limitations : Procedure for determining explosion loads given in (a) above shall have the following limitations:
* (i) Values of *qo* given in Figure 6.2.33(a) are based on tests with gas explosions in room corresponding to ordinary residential flats, and may be applied to considerably different conditions with caution after appropriate adjustment of the values based on more accurate information.
* (ii) Figures 6.2.33(a) and 6.2.33(b) shall be taken as guides only, and probability of occurrence of an explosion shall be checked in each case using appropriate values.
![Magnitude and distribution of internal pressure in a building due to internal gas explosion]()
**Figure 6.2.33 Magnitude and distribution of internal pressure in a building due to internal gas explosion**
#### 2.6.6.2 Minimum design pressure
Walls, floors and roofs and their supporting members separating a use from an explosion exposure, shall be designed to sustain the anticipated maximum load effects resulting from such use including any dynamic effects, but for a minimum internal pressure or suction of 5 kN/m2 , in addition to all other loads specified in this Chapter.
#### 2.6.6.3 Design pressure on relief vents
When pressure-relief vents are used, such vents shall be designed to relieve at a maximum internal pressure of 1.0 kN/m2 .
#### 2.6.6.4 Loads due to other explosions
Loads arising from other types of explosions, such as those from external gas cloud explosions, external explosions due to high explosives (TNT) etc. shall be determined, for specific cases, by rational analyses based on information from reliable references or specialist advice shall be sought.
### **2.6.7 Vertical Forces on Air Raid Shelters**
For the design of air raid shelters located in a building e.g. in the basement below ground level, the characteristic vertical load shall be determined in accordance with provisions of Sec 2.6.7.1 below.
#### 2.6.7.1 Characteristic vertical loads
Buildings in which the individual floors are acted upon by a total distributed live load of up to 5.0 kN/m2 , vertical forces on air raid shelters generally located below ground level, such as a basement, shall be considered to have the characteristic values provided in Table 6.2.27. In the case of buildings having floors that are acted upon by a live load larger than 5.0 kN/m2 , above values shall be increased by the difference between the average live loads on all storeys above the one used as the shelter and 5.0 kN/m2 .
**Table 6.2.28: Characteristic Vertical Loads for an Air Raid Shelter in a Building**
| **No. of Storeys**\*\*(1) \*\***above the Air Raid**
**Shelter** | **Vertical Load, kN/m****2** |
| -------------------------------------------------------------------------------- | --------------------------------------- |
| \<2 | 28 |
| 3 - 4 | 34 |
| >4 | 41 |
| Buildings of particularly stable construction | 28(2) |
| irrespective of the number of storeys | |
| Notes: | |
| (1) Storeys shall mean every usable storey above the shelter floor | |
(2) Buildings of particularly stable construction shall mean buildings having bearing structural elements made from reinforced in-situ concrete.
### **2.6.8 Loads on Helicopter Landing Areas**
In addition to all other applicable loads provided in this Chapter, including the dead load, the minimum live load on helicopter landing or touch down areas shall be one of the loads *L* 1 *, L* 2 or *L* 3 as given below producing the most unfavourable effect:
Where,
* I1 = Actual weight of the helicopter in kN,
I = Fully loaded weight of the helicopter in kN,
* \[ = A distributed load of 5.0 kN/m2 ,
* m = 0.75 for helicopters equipped with hydraulic - type shock absorbers, and
* \= 1.5 for helicopters with rigid or skid-type landing gear.
The live load, 61 shall be applied over the actual areas of contact of landing. The load, 6 shall be a single concentrated load including impact applied over a 300 mm x 300 mm area. The loads 61 and 6 may be applied anywhere within the landing area to produce the most unfavourable effects of load.
### **2.6.9 Erection and Construction Loads**
All loads required to be sustained by a structure or any portion thereof due to placing or storage of construction materials and erection equipment including those due to operation of such equipment shall be considered as erection loads. Provisions shall be made in design to account for all stresses due to such loads.
## **2.7 Combinations of Loads**
### **2.7.1 General**
Buildings, foundations and structural members shall be investigated for adequate strength to resist the most unfavorable effect resulting from the various combinations of loads provided in this Section. The combination of loads may be selected using the provisions of either Sec 2.7.2 or Sec 2.7.3 whichever is applicable. However, once Sec 2.7.2 or Sec 2.7.3 is selected for a particular construction material, it must be used exclusively for proportioning elements of that material throughout the structure.
In addition to the load combinations given in Sections 2.7.2 and 2.7.3 any other specific load combination provided elsewhere in this Code shall also be investigated to determine the most unfavourable effect.
The most unfavourable effect of loads may also occur when one or more of the contributing loads are absent, or act in the reverse direction. Loads such as *F* , *H* or *S* shall be considered in design when their effects are significant. Floor live loads shall not be considered where their inclusion results in lower stresses in the member under consideration. The most unfavourable effects from both wind and earthquake loads shall be considered where appropriate, but they need not be assumed to act simultaneously.
### **2.7.2 Combinations of Load effects for Allowable Stress/Strength Design Method**
#### 2.7.2.1 Basic combinations
Provisions of this Section shall apply to all construction materials permitting their use in proportioning structural members by allowable stress/strength design method. When this method is used in designing structural members, all loads listed herein shall be considered to act in the following combinations. The combination that produces the most unfavorable effect shall be used in design.
1. *D* + *F*
2. *D* + *H* + *F* + *L* + *T*
3. *D* + *H* + *F* + *(Lr* or *R)*
4. *D* + *H* + *F* + 0.75 *(L* + *T )* + *(Lr* or *R)*
5. *D* + *H* + *F* + *(W* or 0.7 *E)*
6. *D* + *H* + *F* + 0.75 *(W* or 0.7 *E)* + 0.75 *L* + 0.75 *(Lr* or *R)*
7. 0.6 *D* + *W* + *H*
8. 0.6 *D* + 0.7 *E* + *H*
When a structure is located in a flood zone or in tidal surge zone, the following load combinations shall be considered:
1. In Coastal Zones vulnerable to tidal surges, 1.5 *Fa* shall be added to other loads in combinations (5), (6); *E* shall be set equal to zero in (5) and (6).
2. In non-coastal Zones, 0.75 *Fa* shall be added to combinations (5), (6) and (7); *E* shall be set equal to zero in (5) and (6).
#### 2.7.2.2 Stress increase
Unless permitted elsewhere in this Code, increases in allowable stress shall not be used with the loads or load combinations given above in Sec 2.7.2.1.
### **2.7.3 Combinations of Load effects for Strength Design Method**
When strength design method is used, structural members and foundations shall be designed to have strength not less than that required to resist the most unfavorable effect of the combinations of factored loads listed in the following Sections:
#### 2.7.3.1 Basic combinations
1. 1.4( *D* + *F* )
2. 1.2( *D* + *F* + *T* ) + 1.6( *L* + *H* ) + 0.5( *Lr or R* )
3. 1.2 *D* + 1.6( *Lr* or *R* ) + ( *L* or 0.8 *W* )
4. 1.2 *D* + 1.6 *W* + *L* + 0.5( *Lr* or *R* )
5. 1.2 *D* + 1.0 *E* + 1.0 *L*
6. 0.9 *D* + 1.6 *W* + 1.6 *H*
7. 0.9 *D* + 1.0 *E* + 1.6 *H*
Each relevant strength limit state shall be investigated. Effects of one or more loads not acting shall be investigated. The most unfavorable effect from both wind and earthquake loads shall be investigated, where appropriate, but they need not be considered to act simultaneously.
Exceptions:
1. The load factor on live load *L* in combinations (3), (4), and (5) is permitted to be reduced to 0.5 for all occupancies in which minimum specified uniformly distributed live load is less than or equal to 5.0 kN/m2 , with the exception of garages or areas occupied as places of public assembly.
2. The load factor on *H* shall be set equal to zero in combinations (6) and (7) if the structural action due to *H* counteracts that due to *W* or *E* . Where lateral earth pressure provides resistance to structural actions from other forces, it shall not be included in *H* but shall be included in the design resistance.
3. For structures designed in accordance with the provisions of Chapter 6, Part 6 of this Code (reinforced concrete structures), where wind load *W* has not been reduced by a directionality factor, it shall be permitted to use 1.3 *W* in place of 1.6 *W* in (4) and (6) above.
When a structure is located in a flood zone or in tidal surge zone, the following load combinations shall be considered:
1. In Coastal Zones vulnerable to tidal surges, 1.6 *W* shall be replaced by 1.6 *W* +2.0 *Fa* in combinations (4) and (6).
2. In Non-coastal Zones, 1.6 *W* shall be replaced by 0.8 *W* +1.0 *Fa* in combinations (4) and (6).
### **2.7.4 Load Combinations for Extraordinary Events**
Where required by the applicable Code, standard, or the authority having jurisdiction, strength and stability shall be checked to ensure that structures are capable of withstanding the effects of extraordinary (i.e., low-probability) events, such as fires, explosions, and vehicular impact.
### **2.7.5 Load Combination for Serviceability**
Serviceability limit states of buildings and structures shall be checked for the load combinations set forth in this Section as well as mentioned elsewhere in this Code. For serviceability limit states involving visually objectionable deformations, repairable cracking or other damage to interior finishes, and other short term effects, the suggested load combinations for checking vertical deflection due to gravity load is
## 1. *D* + *L*
For serviceability limit states involving creep, settlement, or similar long-term or permanent effects, the suggested load combination is:
## 2. *D* + 0.5 *L*
The dead load effect, *D* , used in applying combinations 1 and 2 above may be that portion of dead load that occurs following attachment of nonstructural elements. In applying combination 2 above to account for long term creep effect, the immediate (e.g. elastic) deflection may be multiplied by a creep factor ranging from 1.5 to 2.0. Serviceability against gravity loads (vertical deflections) shall be checked against the limits set forth in Sec 1.2.5 Chapter 1 of this Part as well as mentioned elsewhere in this Code.
For serviceability limit state against lateral deflection of buildings and structures due to wind effect, the following combination shall be used:
3. *D* + 0.5 *L* + 0.7 *W*
Due to its transient nature, wind load need not be considered in analyzing the effects of creep or other long-term actions. Serviceability against wind load using load combination 3 above shall be checked in accordance with the limit set forth in Sec 1.5.6.2 Chapter 1 of this Part.
## **2.8 List of Related Appendices**
Appendix A Equivalence of Nonhomogenous Equations in SI-Metric, MKSMetric, and U.S. Customary Units
Appendix B Local Geology, Tectonic Features and Earthquake Occurrence in the Region
Appendix C Seismic Design Parameters for Alternative Method of Base Shear Calculation
# Chapter 3: Soils and Foundations
Source: https://docs.sayed.app/bnbc/part-6-structural-design/chapter-3-soils-and-foundations
## **3.1 General**
The Soils and Foundations Chapter of the Code is divided into the following three distinct Divisions:
**Division A:** Site Investigations, Soil Classifications, Materials and Foundation Types
* **Division B:** Service Load Design Method of Foundations
* **Division C:** Additional Considerations in Planning, Design and Construction of Building Foundations
Division A (Site Investigations, Soil Classifications, Materials and Foundation Types) consists of the following Sections:
* Site Investigations
* Identification, Classification and Description of Soils
* Materials
* Types of Foundation
Division B (Service Load Design Method of Foundations) has the sections as under:
* Shallow Foundations
* Geotechnical Design of Shallow Foundations
* Geotechnical Design of Deep Foundations
* Field Tests for Driven Piles and Drilled Shafts
Division C (Additional Considerations in Planning, Design and Construction of Building Foundations) deals with the following sections:
* Excavation
* Dewatering
* Slope Stability of Adjoining Building
* Fills
* Retaining Walls for Foundations
* Waterproofing and Damp-proofing
* Foundation on Slopes
* Foundations on Fill and Problematic Soils
* Foundation Design for Dynamic Forces
* Geo-hazards for Buildings
## **3.2 Scope**
The provisions of this Chapter shall be applicable to the design and construction of foundations of buildings and structures for the safe support of dead and superimposed loads without exceeding the allowable bearing stresses, permissible settlements and design capability. Because of uncertainties and randomness involved in sub-soil characteristics, Geotechnical Engineering requires a high degree of engineering judgment. As such the Code provisions of this Chapter provided here under, are kept elaborative for better understanding of the readers. Provisions that are stated in imperative form using “shall” are mandatory. Other provisions of this Chapter should be followed using sound Geotechnical Engineering judgment.
## **3.3 Definitions and Symbols**
### **3.3.1 Definitions**
For the terms used in this Chapter, the following definitions shall apply.
ALLOWABLE It is the minimum of the safe bearing capacity and BEARING CAPACITY safe settlement pressure, so that the foundation/ structure is safe and stable under both shear failure and settlement criteria. It may be denoted by symbol $q_{allow}$. The lateral dimensions of the foundation (width or diameter and the length) are designed on the basis of allowable bearing capacity. Also known as Allowable Bearing Pressure. ALLOWABLE LOAD The maximum load that may be safely applied to a foundation unit, considering both the strength and settlement of the soil, under expected loading and soil conditions.
ANGULAR Angle between the horizontal and any two DISTORTION foundations or two points in a single foundation. AUGUR PILE Same as SCREW PILE. BATTER PILE The pile which is installed at an angle to the vertical in order to carry lateral loads along with the vertical loads. This is also known as RAKER PILE.
BEARING CAPACITY The general term used to describe the load carrying capacity of foundation soil or rock in terms of average pressure that enables it to bear and transmit loads from a structure.
| BEARING SURFACE | The contact surface between a foundation unit and
the soil or rock upon which the foundation rests. |
| ------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BORED PILE | A pile formed into a preformed hole of ground,
usually of reinforced concrete having a diameter
smaller than 600 mm. |
| BOULDER | Particles of rock that will not pass a 12 inch. (300
mm) square opening. |
| CAISSON | A deep foundation unit, relatively large section, sunk
down (not driven) to the ground. This is also called
WELL FOUNDATION. |
| CAST IN-SITU PILE | Same as BORED PILE. |
| CLAY | A
natural
aggregate
of
microscopic
and
submicroscopic mineral grains less than 0.002 mm in
size and plastic in moderate to wide range of water
contents. |
| CLAY MINERAL | A small group of minerals, commonly known as clay
minerals,
essentially
composed
of
hydrous
aluminium silicates with magnesium or iron
replacing wholly or in part some of the aluminium. |
| CLAY SOIL | Same as CLAY. |
| COBBLE | Particles of rock that will pass a 12-in. (300-mm)
square opening and be retained on a 3-in. (75-mm)
sieve. |
| COLLAPSIBLE SOIL | Consists predominant of sand and silt size particles
arranged in a loose honeycomb structure. These soils
are dry and strong in their natural state and
consolidate or collapse quickly if they become wet. |
| CONSOLIDATION
SETTLEMENT | A time dependent settlement resulting from gradual
reduction of volume of saturated soils because of
squeezing out of water from the pores due to
increase in effective stress and hence pore water
pressure. It is also known as primary consolidation
settlement. It is thus a time related process involving
compression, stress transfer and water drainage. |
| DEEP FOUNDATION | A foundation unit that provides support for a
structure transferring loads by end bearing and/or by
shaft resistance at considerable depth below the
ground. Generally, the depth is at least five times the
least dimension of the foundation. |
| DESIGN BEARING
CAPACITY | The maximum net average pressure applied to a soil
or rock by a foundation unit that the foundation soil
or rock will safely carry without the risk of both
shear failure and exceedance of permissible
settlement. It is equal to the least of the two values of
net allowable bearing capacity and safe bearing
pressure. This may also be called ALLOWABLE
BEARING PRESSURE. |
| DESIGN LOAD | The expected un-factored load to a foundation unit. |
| DIFFERENTIAL
SETTEMENT | The difference in the total settlements between two
foundations or two points in the same foundation. |
| DISPERSIVE SOIL | Soils that are structurally unstable and disperse in
water into basic particles i.e. sand, silt and clay.
Dispersible soils tend to be highly erodible.
Dispersive soils usually have a high Exchangeable
Sodium Percentage (ESP). |
| DISPLACEMENT PILE | Same as DRIVEN PILE. |
| DISTORTION
SETTLEMENT | Same as ELASTIC SETTLEMENT. |
| DOWNDRAG | The transfer of load (drag load) to a deep foundation,
when soil settles in relation to the foundation. This is
also known as NEGATIVE SKIN FRICTION. |
| DRILLED PIER | A deep foundation generally of large diameter shaft
usually more than 600 mm and constructed by
drilling and excavating into the soil. |
| DRILLED SHAFT | Same as DRILLED PIER. |
| DRIVEN PILE | A pile foundation pre-manufactured and placed in
ground by driving, jacking, jetting or screwing. |
| EFFECTIVE STRESS | The pressure transmitted through grain to grain at the
contact point through a soil mass is termed as
effective stress or effective pressure. |
| ELASTIC SETTLEMENT | It is attributed due to lateral spreading or elastic
deformation of dry, moist or saturated soil without a
change in the water content and volume. |
| END BEARING | The load being transmitted to the toe of a deep
foundation and resisted by the bearing capacity of
the soil beneath the toe. |
| EXCAVATION | The space created by the removal of soil or rock for
the purpose of construction. |
| EXPANSIVE SOIL | These are clay soils expand when they become
wetted and contract when dried. These are formed of
clay minerals like montmorillonite and illite. |
| FACTOR OF SAFETY | The ratio of ultimate capacity to design (working)
capacity of the foundation unit. |
| FILL | Man-made deposits of natural earth materials (soil,
rock) and/or waste materials. |
| FOOTING | A foundation constructed of masonry, concrete or
other material under the base of a wall or one or
more columns for the purpose of spreading the load
over a larger area at shallower depth of ground
surface. |
| FOUNDATION | Lower part of the structure which is in direct contact
with the soil and transmits loads to the ground. |
| FOUNDATION
ENGINEER | A graduate Engineer with at least five years of
experience in civil engineering particularly in
foundation design or construction. |
| GEOTECHNICAL | Engineer with Master’s degree in geotechnical |
| ENGINEER | engineering having at least 2 (two) years of
experience in geotechnical design/construction or
graduate in civil engineering/engineering geology
having 10 (ten) years of experience in geotechnical
design/construction. |
| GRAVEL | Particles of rock that will pass a 3-in. (75-mm) sieve
and be retained on a No. 4 (4.75-mm) sieve. |
| GROSS PRESSURE | The total pressure at the base of a footing due to the
weight of the superstructure and the original
overburden pressure. |
| GROSS ALLOWABLE
BEARING PRESSURE | The maximum gross average pressure of loading that
the soil can safely carry with a factor of safety
considering risk of shear failure. This may be
calculated by dividing gross ultimate bearing
capacity with a factor of safety. |
| GROUND WATER
TABLE | The level of water at which porewater pressure is
equal to atmospheric pressure. It is the top surface of
a free body of water (piezometric water level) in the
ground. |
| IMMEDIATE
SETTLEMENT | This vertical compression occurs immediately after
the application of loading either on account of elastic
behaviour that produces distortion at constant
volume and on account of compression of air void.
For sands, even the consolidation component is
immediate. |
| INORGANIC SOIL | Soil of mineral origin having small amount usually
less than 5 percent of organic matter content. |
| LATERALLY LOADED
PILE | A pile that is installed vertically to carry mainly the
lateral loads. |
| MAT FOUNDATION | See RAFT. |
| NEGATIVE SKIN
FRICTION | See DOWNDRAG. |
| NET PRESSURE | The gross pressure minus the surcharge pressure i.e.
the overburden pressure of the soil at the foundation
level. |
| NET SAFE BEARING
CAPACITY | The maximum net pressure that can be safely applied
from the foundation on the soil at its base, and at
which the shear failure of the soil is avoided with a
suitable factor of safety ($FS$). It is denoted by
symbol $q_{ns}$. Thus, $q_{ns} = \dfrac{q_{nu}}{FS}$. |
| NET ULTIMATE
BEARING CAPACITY | The minimum net pressure at the base of the
foundation, excluding the weight of the overburden,
at which the soil fails in shear due to the load on the
foundation from superstructure. It is denoted by the
symbol $q_{net}$. Thus, $q_{net} = q_{ult} - q'$ where, $q'$ is the
effective stress at foundation level due to overburden
soil. |
| ORGANIC SOIL | Soil having appreciable/significant amount of
organic matter content to influence the soil
properties. |
| OVERCONSOLIDATION
RATIO (OCR) | The ratio of the preconsolidation pressure (maximum
past pressure) to the existing effective overburden
pressure of the soil. |
| PEAT SOIL | An organic soil with high organic content, usually
more than 75% by weight, composed primarily of
vegetable tissue in various stages of decomposition
usually with an organic odor, a dark brown to black
color, a spongy consistency, and a texture ranging
from fibrous to amorphous. Fully decomposed
organic soils are known as MUCK. |
| PILE | A slender deep foundation unit made of materials
such as steel, concrete, wood, or combination thereof
that transmits the load to the ground by skin friction,
end bearing and lateral soil resistance. |
| PILE CAP | A pile cap is a special footing needed to transmit the
column load to a group or cluster of piles. |
| PILE HEAD | The upper small length of a pile. Also known as pile
top. |
| PILE SHOE | A separate reinforcement or steel form attached to
the bottom end (pile toe) of a pile to facilitate
driving, to protect the pile toe, and/or to improve the
toe resistance of the pile. |
| PILE TOE | The bottom end of a pile. Also known as pile tip. |
| PORE WATER
PRESSURE | The pressure induced in the water or vapour and
water filling the pores of soil. This is also known as
neutral stress. |
| PRESUMPTIVE | The net
approximate
pressure
prescribed
as |
| BEARING CAPACITY | appropriate for the particular type of ground to be
used in preliminary designs of foundations |
| RAFT | A relatively large spread foundation supporting an
arrangement of columns or walls in a regular or
irregular layout transmitting the loads to the soil by
means of a continuous slab and/or beams, with or
without depressions or openings. This is also known
as MAT FOUNDATION. |
| RAKER PILE | See BATTER PILE. |
| ROCK | A natural aggregate of one or more minerals that are
connected by strong and permanent cohesive forces. |
| ROTATION | It is the angle between the horizontal and any two
foundations or two points in a single foundation. |
| RELATIVE ROTATION | Same as ANGULAR DISTORTION |
| REPLACEMENT PILE | Same as BORED PILE. |
| SAFE BEARING
CAPACITY | It is the maximum gross pressure that can carry
safely, without shear failure. It is denoted by
symbol $q_{safe}$. Thus, $q_{safe} = q_{ns} + q'$. When the
excavation for foundation is backfilled, $q_{safe} = q_{ns}$. |
| SAFE SETTLEMENT
PRESSURE | The maximum pressure that can be applied from the
foundation on the soil at its base such that the
settlement of the foundation/structure is less than or
equal to the permissible settlement. It may be
denoted by symbol $q_{sp}$. |
| SAND | Aggregates of rounded, sub-rounded, angular, sub-
angular or flat fragments of more or less unaltered
rock or minerals which is larger than 75 μm and
smaller than 4.75 mm in size. |
| SCREW PILE | A pre-manufactured pile consisting of steel helical
blades and a shaft placed into ground by screwing. |
| SECONDARY
CONSOLIDATION | This is the settlement speculated to be due to the
plastic deformation of the soil as a result of some |
| SETTLEMENT | complex colloidal-chemical processes or creep under
imposed long term loading. |
| SERVICE LOAD
SETTLEMENT | The expected un-factored load to a foundation unit.
The downward vertical movement of foundation
under load. When settlement occurs over a large
area, it is sometimes called subsidence. |
| SHAFT RESISTANCE | The resistance mobilized on the shaft (side) of a
deep foundation. Upward resistance is called
positive shaft resistance. Downward force on the
shaft is called negative shaft resistance. |
| SHALLOW
FOUNDATION | A foundation unit that provides support for a
structure transferring loads at a small depth below
the ground. Generally, the depth is less than two
times the least dimension of the foundation. |
| SILT | Soil passing a No. 200 (75-μm) sieve either non-
plastic or plastic. |
| SOIL | A loose or soft deposit of particles of mineral and/or
organic origin that can be separated by such gentle
mechanical means as agitation in water. |
| SOIL PARTICLE SIZE | The sizes of particles that make up soil varying over
a wide range. Soil particles are generally gravel,
sand, silt and clay, though the terms boulder and
cobble can be used to describe larger sizes of gravel. |
| TILT | Rotation of the entire superstructure or at least a
well-defined part of it. |
| TOTAL SETTLEMENT | The total downward vertical displacement of a
foundation base under load from its as-constructed
position. It is the summation of immediate
settlement, consolidation settlement and secondary
consolidation settlement of the soil. |
| ULTIMATE BEARING
CAPACITY | The minimum gross pressure at the base of the
foundation at which the soil fails in shear due to the
load on the foundation from superstructure. It is
denoted by the symbol $q_{ult}$ and obtained from
bearing capacity equation containing soil/ground
properties,
depth
of
foundation,
foundation
dimensions and shapes, and loading conditions. Also
known as Gross Ultimate Bearing Capacity. |
### **3.3.2 Symbols and Notation**
Every symbol used in this Chapter is explained where it first appears in the text. However, for convenience of the reader, a list of main symbols and notation is provided as under. Other common symbols and notation like those of soil classifications are not included in this list.
* $A$ = Cross sectional area of pile
* $A_b$ = End bearing area of pile
* $A_s$ = Skin friction area (perimeter area) of pile
* $B$ = Width of footing/foundation (Sec 3.9.6, Sec 3.20.2)
* $B$ = Smallest dimension of pile group (Sec 3.10.5)
* $B_p$ = Width of plate
* $B_r$ = Reference width (300 mm) for computation of pile settlement
* $CEC$ = Cation exchange capacity
* $CRR$ = Cyclic resistance ratio
* $CSR$ = Cyclic stress ratio
* $C_c$ = Compression index of soil
* $C_p$ = Empirical coefficient used for pile settlement computation
* $C_u$ = Uniformity coefficient
* $C_z$ = Coefficient of curvature
* $D$ = Diameter or width of pile
* $D_b$ = Diameter of pile at base
* $D_c$ = Critical depth of soil layer
* $D_{10}$ = Effective grain size; the size of soil particle from which 10 percent of the soil is finer
* $D_{30}$ = The size of soil particle from which 30 percent of the soil is finer
* $D_{60}$ = The size of soil particle from which 60 percent of the soil is finer
* $EI$ = Flexural rigidity of footing
* $Em_gP$ = Exchangeable magnesium percentage
* $E_p$ = Modulus of elasticity of pile material
* $E_s$ = Modulus of elasticity of soil
* $ESP$ = Exchangeable sodium percentage
* $F_L$ = Factor of safety against liquefaction
* $FS$ = Factor of safety
* $G$ = Modulus of rigidity
* $H$ = Height of wall from foundation footing (Sec 3.9.4)
* $H$ = Layer thickness (Sec 3.10.5)
* $H$ = Thickness of sample (Sec 3.5.6)
* $H'$ = Final thickness of sample (Sec 3.5.6)
* $I_p$ = Plasticity index
* $I_{subs}$ = Relative subsidence
* $K$ = Coefficient of earth pressure
* $K_o$ = Coefficient of earth pressure at rest
* $L$ = Length of pile (Sec 3.10)
* $L$ = Length of deflected part of wall/raft or centre to centre distance between columns. (Sec 3.9.4)
* $LL$ = Liquid limit
* $N$ = Standard penetration test value (SPT)
* $N_{60}$ = Corrected SPT value for field procedures
* $\bar{N}_{60}$ = Average SPT $N_{60}$ value
* $(N_1)_{60}$ = Corrected SPT value for overburden pressure (for sandy soil)
* $N_c, N_q, N_\gamma$ = Bearing capacity factors
* $OCR$ = Overconsolidation ratio
* $PI$ = Plasticity index; same as $I_p$
* $Q_{allow}$ = Allowable load
* $Q_p$ = End bearing at the base or tip of the pile
* $Q_p$ = Load transferred to the soil at pile tip level
* $Q_s$ = Skin friction or shaft friction or side shear
* $Q_{ult}$ = Ultimate bearing/load carrying capacity
* $R_s$ = Group settlement ratio of pile group
* $S_{ax}$ = Settlement due to axial deformation
* $S_g$ = Settlement of pile group
* $S_{pt}$ = Settlement at pile tip
* $S_{sf}$ = Settlement of pile due to skin friction
* $S_r$ = Degree of saturation
* $S_{t(single)}$ = Total settlement of a single pile
* $W$ = Weight of the pile
* $WPI$ = Weighted plasticity index
* $a_{max}$ = Peak horizontal acceleration on the ground surface
* $c$ = Apparent cohesion of soil
* $c_u$ = Undrained cohesion of soil
* $d_p$ = Diameter of pile
* $e$ = Void ratio
* $e_c$ = Critical void ratio
* $e_L$ = Void ratio at liquid limit
* $e_P$ = Void ratio at plastic limit
* $e_i$ = Initial void ratio
* $e_o$ = Initial void ratio; same as $e_i$
* $f_b$ = End bearing resistance on unit tip area of pile
* $f_n$ = Natural frequency
* $f_s$ = Skin frictional resistance on unit surface area of pile
* $f_s$ = Adhesive stress (Sec. 3.10.1.12)
* $g$ = Gravitational acceleration
* $k$ = Modulus of sub-grade reaction
* $k_p$ = Stiffness of soil
* $k_s$ = Coefficient of horizontal soil stress
* $m$ = Total mass of machine foundation system
* $m_f$ = Mass of foundation block
* $m_s$ = Mass of soil
* $n$ = Number of pile in a group
* $q_{allow}$ = Allowable bearing capacity of shallow foundation
* $q_o$ = Ultimate end bearing capacity pile
* $q_{ns}$ = Net safe ultimate bearing capacity of shallow foundation
* $q_{nu}$ = Net ultimate bearing capacity of shallow foundation
* $q_{safe}$ = Safe ultimate bearing capacity
* $q_{sp}$ = Safe settlement pressure of shallow foundation
* $q_u$ = Unconfined compressive strength
* $q_{ult}$ = Ultimate bearing capacity of shallow foundation
* $r_d$ = Stress reduction coefficient to allow for the deformability of the soil column
* $s_u$ = undrained shear strength; same as $c_u$
* $w_L$ = Liquid limit; same as LL
* $z$ = Depth
* $\Delta z_i$ = Thickness of any ($i^{th}$) layer
* $\alpha$ = Adhesion factor
* $\beta$ = Ratio of footing length to width (Sec 3.9.6.8)
* $\beta$ = Friction factor due to overburden (3.10.1)
* $\gamma, \gamma_t$ = Unit weight of the soil
* $\gamma_w$ = Unit weight of water
* $\delta$ = Total settlement
* $\delta_c$ = Consolidation settlement
* $\delta_e$ = Elastic settlement
* $\delta_i$ = Immediate settlement
* $\delta_s$ = Secondary consolidation settlement
* $\mu$ = Poisson's ratio of soil
* $\sigma_o'$ = Initial effective stress at mid-point of a soil layer
* $\sigma_p'$ = Increase in effective stress at mid-point of a soil layer due to increase in stress
* $\sigma_r'$ = Reference stress (100 kPa) for computation of pile settlement
* $\sigma_v$ = The total vertical stress
* $\sigma_v'$ = Effective vertical stress
* $\sigma_z'$ = Effective vertical stress; same as $\sigma_v'$
* $\tau_{max}$ = Maximum shear stress
* $\phi$ = Apparent angle of internal friction
* $\phi'$ = Effective/drained angle of internal friction
* $\phi_s$ = Soil shaft interface friction angle
* $\omega_n$ = natural circular frequency
**Division A: Site Investigations, Soil Classifications, Materials and Foundation Types (Sections 3.4 to 3.7)**
## **3.4 Site Investigations**
### **3.4.1 Sub-Surface Survey**
Depending on the type of project thorough investigations has to be carried out for identification, location, alignment and depth of various utilities, e.g., pipelines, cables, sewerage lines, water mains etc. below the surface of existing ground level. Detailed survey may also be conducted to ascertain the topography of existing ground.
### **3.4.2 Sub-Soil Investigations**
Sub soil investigation shall be done describing the character, nature, load bearing capacity and settlement capacity of the soil before constructing a new building and structure or for alteration of the foundation of an existing structure. The aims of a geotechnical investigation are to establish the soil, rock and groundwater conditions, to determine the properties of the soil and rock, and to gather additional relevant knowledge about the site. Careful collection, recording and interpretation of geotechnical information shall be made. This information shall include ground conditions, geology, geomorphology, seismicity and hydrology, as relevant. Indications of the variability of the ground shall be taken into account.
An engineering geological study may be an important consideration to establish the physiographic setting and stratigraphic sequences of soil strata of the area. Geological and agricultural soil maps of the area may give valuable information of site conditions.
During the various phases of sub-soil investigations, e.g. drilling of boreholes, field tests, sampling, groundwater measurements, etc. a competent graduate engineer having experiences in supervising sub-soil exploration works shall be employed by the drilling contractor.
### **3.4.3 Methods of Exploration**
Sub soil exploration process may be grouped into three types of activities such as: reconnaissance, exploration and detailed investigations. The reconnaissance method includes geophysical measurements, sounding or probing, while exploratory methods involve various drilling techniques. Field investigations should comprise :
* (i) Drilling and/or excavations (test pits including exploratory boreholes) for sampling;
* (ii)Groundwater measurements;
* (iii)Field tests.
Examples of the various types of field investigations are:
* (i) Field testing (e.g. CPT, SPT, dynamic probing, WST, pressuremeter tests, dilatometer tests, plate load tests, field vane tests and permeability tests);
* (ii)Soil sampling for description of the soil and laboratory tests;
* (iii)Groundwater measurements to determine the groundwater table or the pore pressure profile and their fluctuations
* (iv) Geophysical investigations (e.g. seismic profiling, ground penetrating radar, resistivity measurements and down hole logging);
* (v) Large scale tests, for example to determine the bearing capacity or the behaviour directly on prototype elements, such as anchors.
Where ground contamination or soil gas is expected, information shall be gathered from the relevant sources. This information shall be taken into account when planning the ground investigation. Some of the common methods of exploration, sampling and ground water measurements in soils are described in Appendix D.
### **3.4.4 Number and Location of Investigation Points**
The locations of investigation points, e.g., pits and boreholes shall be selected on the basis of the preliminary investigations as a function of the geological conditions, the dimensions of the structure and the engineering problems involved. When selecting the locations of investigation points, the following should be observed:
* (i) The investigation points should be arranged in such a pattern that the stratification can be assessed across the site;
* (ii) The investigation points for a building or structure should be placed at critical points relative to the shape, structural behaviour and expected load distribution (e.g. at the corners of the foundation area);
* (iii) For linear structures, investigation points should be arranged at adequate offsets to the centre line, depending on the overall width of the structure, such as an embankment footprint or a cutting;
* (iv) For structures on or near slopes and steps in the terrain (including excavations), investigation points should also be arranged outside the project area, these being located so that the stability of the slope or cut can be assessed. Where anchorages are installed, due consideration should be given to the likely stresses in their load transfer zone;
* (v) The investigation points should be arranged so that they do not present a hazard to the structure, the construction work, or the surroundings (e.g. as a result of the changes they may cause to the ground and groundwater conditions);
* (vi) The area considered in the design investigations should extend into the neighbouring area to a distance where no harmful influence on the neighbouring area is expected. Where ground conditions are relatively uniform or the ground is known to have sufficient strength and stiffness properties, wider spacing or fewer investigation points may be applied. In either case, this choice should be justified by local experience.
* (vii) The locations and spacing of sounding, pits and boreholes shall be such that the soil profiles obtained will permit a reasonably accurate estimate of the extent and character of the intervening soil or rock masses and will disclose important irregularities in subsurface conditions.
* (viii) For building structures, the following guidelines shall be followed:
On uniform soils, at least three borings, not in one line, should be made for small buildings and at least five borings one at each corner and one at the middle should be made for large buildings. As far as possible the boreholes should be drilled closed to the proposed foundations but outside their outlines.
Spacing of exploration depends upon nature and condition of soil, nature and size of the project. In uniform soil, spacing of exploration (boring) may be 30 m to 100 m apart or more and in very erratic soil conditions, spacing of 10 m or less may be required. The following chart gives an approximate idea about spacing of boring required for small and multistoried buildings having different horizontal stratification of soil.
| **Type of** | **Spaci** | **ng of Bore Hole** | **s (m)** |
| --------------- | ---------------- | ------------------- | ----------------- |
| **Building** | **Type of Soil** | **in Horizontal S** | **tratification** |
| | **Uniform** | **Average** | **Erratic** |
| Small buildings | 60 | 30 | 15 |
| Multistoried | 45 | 30 | 15 |
| buildings | | | |
* (ix) For large areas covering industrial and residential colonies, the geological nature of the terrain will help in deciding the number of boreholes or trial pits. The whole area may be divided into grid pattern with Cone Penetration Tests (Appendix D) performed at every 100 m grid points. The number of boreholes or trial pits shall be decided by examining the variation in penetration curves. At least 67% of the required number of borings or trial pits shall be located within the area under the building.
### **3.4.5 Depth of Exploration**
The depth of investigations shall be extended to all strata that will affect the project or are affected by the construction *.* The depth of exploration shall depend to some extent on the site and type of the proposed structure, and on certain design considerations such as safety against foundation failure, excessive settlement, seepage and earth pressure. Cognizance shall be taken of the character and sequence of the subsurface strata. The site investigation should be carried to such a depth that the entire zone of soil or rock affected by the changes caused by the building or the construction will be adequately explored. A rule of thumb used for this purpose is to extend the borings to a depth where the additional load resulting from the proposed building is less than 10% of the average load of the structure, or less than 5% of the effective stress in the soil at that depth. Where the depth of investigation cannot be related to background information, the following guide lines are suggested to determine the depth of exploration:
* (i) Where substructure units will be supported on spread footings, the minimum depth boring should extend below the anticipated bearing level a minimum of two footing widths for isolated, individual footings where length ≤ 2 times of width, and four footing widths for footings where length > 5 times of width. For intermediate footing lengths, the minimum depth of boring may be estimated by linear interpolation as a function of length between depths of two times width and five times width below the bearing level. Greater depth may be required where warranted by local conditions.
* (ii) For more heavily loaded structures, such as multistoried structures and for framed structures, at least 50% of the borings should be extended to a depth equal to 1.5 times the width of the building below the lowest part of the foundation.
* (iii) Normally the depth of exploration shall be 1.5 times the estimated width or the least dimension of the footing below the foundation level. If the pressure bulbs for a number of loaded areas overlap, the whole area may be considered as loaded and exploration shall be carried down to one and a half times the least dimension. In weak soils, the exploration shall be continued to a depth at which the loads can be carried by the stratum in question without undesirable settlement or shear failure.
* (iv) Where substructure units will be supported on deep foundations, the depth boring should extend a minimum of 6 m below the anticipated pile of shaft tip elevation. Where pile or shaft groups will be used, the boring should extend at least two times the maximum pile or shaft group dimension below the anticipated tip elevation, unless the foundation will be end bearing on or in rock.
* (v) For piles bearing on rock, a minimum of 1.5 m of rock core should be obtained at each boring location to ensure the boring has not been terminated in a boulder.
* (vi) For shafts supported on or extending into rock, a minimum of 1.5 m of rock core, or a length of rock core equal to at least three times the shaft diameter for isolated shafts or two times the maximum shaft group dimension for a shaft group, whichever is greater, should be obtained to ensure that the boring had not been terminated in a boulder and to determine the physical properties of rock within the zone of foundation influence for design.
* (vii) The depth, to which weathering process affects the deposit, shall be regarded as the minimum depth of exploration for a site. However, in no case shall this depth be less than 2 m, but where industrial processes affect the soil characteristics, this depth may be more.
* (viii) At least one boring should be carried out to bedrock, or to well below the anticipated level of influence of the building. Bedrock should be ascertained by coring into it to a minimum depth of 3 m.
### **3.4.6 Sounding and Penetration Tests**
Subsurface soundings are used for exploring soil strata of an erratic nature. They are useful to determine the presence of any soft pockets between drill holes and also to determine the density index of cohesionless soils and the consistency of cohesive soils at desired depths. A field test called Vane Shear Test may be used to determine the shearing strength of the soil located at a depth below the ground.
Penetration tests consist of driving or pushing a standard sampling tube or a cone. The devices are also termed as penetrometers, since they penetrate the subsoil with a view to measuring the resistance to penetrate the soil strata. If a sampling tube is used to penetrate the soil, the test is referred to as Standard Penetration Test (or simply SPT). If a cone is used, the test is called a Cone Penetration Test. If the penetrometer is pushed steadily into the soil, the procedure is known as Static Penetration Test. If driven into the soil, it is known as Dynamic Penetration Test. Details of sounding and penetrations tests are presented in Appendix D.
### **3.4.7 Geotechnical Investigation Report**
The results of a geotechnical investigation shall be compiled in the Geotechnical Investigation Report which shall form a part of the Geotechnical Design Report. The Geotechnical Investigation Report shall consist of the following :
* (i) A presentation of all appropriate geotechnical information on field and laboratory tests including geological features and relevant data;
* (ii) A geotechnical evaluation of the information, stating the assumptions made in the interpretation of the test results.
The Geotechnical Investigation Report shall state known limitations of the results, if appropriate. The Geotechnical Investigation Report should propose necessary further field and laboratory investigations, with comments justifying the need for this further work. Such proposals should be accompanied by a detailed programme for the further investigations to be carried out. The presentation of geotechnical information shall include a factual account of all field and laboratory investigations. The factual account should include the following information :
* (i) The purpose and scope of the geotechnical investigation including a description of the site and its topography, of the planned structure and the stage of the planning the account is referring to;
* (ii)The names of all consultants and contractors;
* (iii)The dates between which field and laboratory investigations were performed;
* (iv)The field reconnaissance of the site of the project and the surrounding area noting particularly :
* evidence of groundwater;
* behaviour of neighbouring structures;
* exposures in quarries and borrow areas;
* areas of instability;
* difficulties during excavation;
* history of the site;
* geology of the site,
* survey data with plans showing the structure and the location of all investigation points;
* local experience in the area;
* information on the seismicity of the area.
The presentation of geotechnical information shall also include documentation of the methods, procedures and results including all relevant reports of :
* (i) desk studies;
* (ii)field investigations, such as sampling, field tests, groundwater measurements and technical specifications of field equipment used
* (iii)laboratory tests and test standard followed
The results of the field and laboratory investigations shall be presented and reported according to the requirements defined in the ASTM or equivalent standards applied in the investigations.
## **3.5 Identification, Classification and Description af Soils**
### **3.5.1 Identification of Soils**
Samples and trial pits should be inspected visually and compared with field logs of the drillings so that the preliminary ground profile can be established. For soil samples, the visual inspection should be supported by simple manual tests to identify the soil and to give a first impression of its consistency and mechanical behaviour. A standard visual-manual procedure of describing and identifying soils may be followed.
Soil classification tests should be performed to determine the composition and index properties of each stratum. The samples for the classification tests should be selected in such a way that the tests are approximately equally distributed over the complete area and the full depth of the strata relevant for design.
### **3.5.2 Particle Size Classification of Soils**
Depending on particle sizes, main soil types are gravel, sand, silt and clay. However, the larger gravels can be further classified as cobble and boulder. The soil particle size shall be classified in accordance with Table 6.3.1.
**Table 6.3.1: Particle Size Ranges of Soils**
| **Soil Type** | | **Particl**
**Range** | **e S**
**(m** | **ize**
**m)** | **Retained on Mesh**
**Size/ Sieve No.** |
| ------------- | ------------- | -------------------------- | ------------------- | ------------------- | --------------------------------------------- |
| Boulder | | | > | 300 | 12″ |
| Cobble | | 300 | – | 75 | 3″ |
| Gravel: | Coarse Gravel | 75 | – | 19 | 3/4″ |
| | Medium Gravel | 19 | – | 9.5 | 3/8″ |
| | Fine Gravel | 9.5 | – | 4.75 | No. 4 |
| Sand: | Coarse Sand | 4.75 | – | 2.00 | No. 10 |
| | Medium Sand | 2.00 | – | 0.425 | No. 40 |
| | Fine Sand | 0.425 | – | 0.075 | No. 200 |
| Silt | | 0.075 | – | 0.002 | --- |
| Clay | | | \< | 0.002 | --- |
### **3.5.3 Engineering Classification of Soils**
Soils are divided into three major groups, coarse grained, fine grained and organic. The classification is based on classification test results namely grain size analysis and consistency test. The coarse grained soils shall be classified using Table 6.3.2. Outlines of organic and inorganic soil separations are also provided in Table 6.3.2. The fine grained soils shall be classified using the plasticity chart shown in Figure 6.3.1. In this context, this Code adopts the provisions of ASTM D2487. In addition to these classifications, a soil shall be described by its colour, particle angularity (for coarse grained soils) and consistency. Further to the above classification soils exhibiting swelling or collapsing characteristic shall be recorded. For undisturbed soils information on stratification, compactness, cementation, moisture conditions and drainage characteristics shall be included.
**Table 6.3.2: Engineering Classification of Soils (Criteria for Assigning Group Symbols and Names using Laboratory Tests*A*)**
| Major Division | Group Symbol | Group Name*B* | Percent finer than 0.075 mm | Other Criteria |
| ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------ | -------------------------------------------------------------------------------------------------------- | --------------------------- | --------------------------------------------------------------------------------------------------------------------------------------- |
| Coarse grained soils (more than 50% of material retained on No. 200 sieve, 0.075 mm) — Gravels (more than 50% of coarse fraction retained on No. 4 sieve, 4.75 mm) — Clean gravels | GW | Well graded gravels, sandy gravels, sand gravel mixture, little or no fines.*D* | \< 5*E* | Cu ≥ 4 and 1 ≤ Cz ≤ 3*C* |
| Coarse grained soils — Gravels — Clean gravels | GP | Poorly graded gravels, sandy gravels, Sand gravel mixture, little or no fines.*D* | \< 5*E* | Cu \< 4 and/or 1 > Cz > 3*C* |
| Coarse grained soils — Gravels — Gravel with fines | GM | Silty gravels, silty sandy gravels.*D, F, G* | > 12*E* | IP \< 4 or the limit values below 'A' line of plasticity chart (for 4 > IP > 7 and limit values above 'A' line, dual symbol required\*) |
| Coarse grained soils — Gravels — Gravel with fines | GC | Clayey gravels, silty clayey gravels.*D, F, G* | > 12*E* | IP > 7 and the limit values above 'A' line of Plasticity Chart |
| Coarse grained soils — Sands (over 50% of coarse fraction smaller than 4.75 mm) — Clean Sands | SW | Well graded sand, gravelly sand, little or no fines.*H* | \< 5*E* | Cu ≥ 6 and 1 ≤ Cz ≤ 3*C* |
| Coarse grained soils — Sands — Clean Sands | SP | Poorly graded sands, gravelly sand, little or no fines.*H* | \< 5*E* | Cu \< 6 and/or 1 > Cz > 3*C* |
| Coarse grained soils — Sands — Sands with fines | SM | Silty sand, poorly graded sand silt mixtures.*F, G, H* | > 12*E* | IP \< 4 or the limit values below 'A' line of Plasticity chart (for 4 > IP > 7 and limit values above A-line, dual symbols required) |
| Coarse grained soils — Sands — Sands with fines | SC | Clayey sand, sand clay mixtures.*F, G, H* | > 12*E* | IP > 7 and the limit values above 'A' line of plasticity chart |
| Fine grained soils (over 50% of the material smaller than 0.075 mm) — Silts & Clays, wL \< 50 — Inorganic | ML | Silt of low to medium compressibility, very fine sands, rock flour, silt with sand.*K, L, M* | — | Limit values on or below 'A' line of plasticity chart & IP \< 4 |
| Fine grained soils — Silts & Clays, wL \< 50 — Inorganic | CL | Clays of low to medium plasticity, gravelly clay, sandy clay, silty clay, lean clay.*K, L, M* | — | Limit values above 'A' line of plasticity chart and/or IP > 4 |
| Fine grained soils — Silts & Clays, wL \< 50 — Organic | OL | Organic clay*K, L, M, N* and Organic silt*K, L, M, O* of low to medium plasticity | — | Liquid limit (oven dried) / Liquid limit (undried) \< 0.75 |
| Fine grained soils — Silts & Clays, wL ≥ 50 — Inorganic | MH | Silt of high plasticity, micaceous fine sandy or silty soil, elastic silt.*K, L, M* | — | Limit values on or below 'A' line of plasticity chart |
| Fine grained soils — Silts & Clays, wL ≥ 50 — Inorganic | CH | High plastic clay, fat clay.*K, L, M* | — | Limit values above 'A' line of plasticity chart |
| Fine grained soils — Silts & Clays, wL ≥ 50 — Organic | OH | Organic clay of high plasticity.*K, L, M, P* | — | Liquid limit (oven dried) / Liquid limit (undried) \< 0.75 |
| Soils of high organic origin | PT | Peat and highly organic soils.*K, L, M, Q* | — | Identified by colour, odour, fibrous texture and spongy characteristics. |
Notes:
*A* Based on the material passing the 3-in. (75-mm) sieve.
*B* If field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name.
*C* Cu = D60/D10, CZ = (D30)2 / (D10×D60)
*D* If soil contains ≥ 15% sand, add "with sand" to group name.
*E* Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded gravel with silt; GW-GC well-graded gravel with clay; GP-GM poorly graded gravel with silt; GP-GC poorly graded gravel with clay.
*F* If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.
*G* If fines are organic, add "with organic fines" to group name.
*H* If soil contains ≥ 15% gravel, add "with gravel" to group name.
*I* Sands with 5 to 12% fines require dual symbols: SW-SM well-graded sand with silt; SW-SC well-graded sand with clay; SP-SM poorly graded sand with silt; SP-SC poorly graded sand with clay.
*J* If Atterberg limits plot in hatched area, soil is a CL-ML, silty clay.
*K* If soil contains 15 to 29% plus No. 200, add "with sand" or "with gravel," whichever is predominant.
*L* If soil contains ≥30% plus No. 200, predominantly sand, add "sand" to group name.
*M* If soil contains ≥ 30% plus No. 200, predominantly gravel, add "gravelly" to group name.
*N* PI ≥ 4 and plots on or above "$\gamma$ line.
*O* PI \< 4 or plots below "$\gamma$ line.
*P* PI plots on or above "$\gamma$ line.
*Q* PI plots below "$\gamma$ line.
\* Dual symbol required.
![Plasticity chart based on materials passing 425 μm sieve showing relationship between plasticity index and liquid limit]()
### **3.5.4 Identification and Classification of Organic Soils**
The presence of organic matter can have undesirable effects on the engineering behaviour of soil. For example, the bearing capacity is reduced, the compressibility is increased and, swelling and shrinkage potential is increased due to organic content. Organic content tests are used to classify the soil. In soil with little or no clay particles and carbonate content, the organic content is often determined from the loss on ignition at a controlled temperature. Other suitable tests can also be used. For example, organic content can be determined from the mass loss on treatment with hydrogen peroxide (H2O2), which provides a more specific measure of organics. Organic deposits are due to decomposition of organic matters and found usually in topsoil and marshy place. A soil deposit in organic origin is said to peat if it is at the higher end of the organic content scale (75% or more), organic soil at the low end, and muck in between. Peat soil is usually formed of fossilized plant minerals and characterized by fiber content and lower decomposition. The peats have certain
characteristics that set them apart from moist mineral soils and required special considerations for construction over them. This special characteristic includes, extremely high natural moisture content, high compressibility including significant secondary and even tertiary compression and very low undrained shear strength at natural moisture content.
However, there are many other criteria existed to classify the organic deposits and it remains still as controversial issue with numerous approaches available for varying purpose of classification. A possible approach is being considered by the American society for Testing and Materials for classifying organic soils having varying amount of organic matter contents. The classification is given in Table 6.3.3.
**Table 6.3.3: Classification and Description of Organic Soils (after Edil, 1997)**
| **Organic Content** | **Description** |
| -------------------- | --------------------------------------------------------------------------------------------------------------------------------------------- |
| **(ASTM D2974-07a)** | |
| \< 5 % | Little effect on behavior; considered inorganic soil. |
| 6 \~ 20 % | Effects properties but behavior is still like mineral soils;
organic silts and clays. |
| 21 \~ 74 % | Organic
matter
governs
properties;
traditional
soil
mechanics may be applicable; silty or clayey organic soils. |
| > 75 % | Displays behavior distinct from traditional soil mechanics
especially at low stress. |
### **3.5.5 Identification and Classification of Expansive Soils**
Expansive soils are those which swell considerably on absorption of water and shrink on the removal of water. In monsoon seasons, expansive soils imbibe water, become soft and swell. In drier seasons, these soils shrink or reduce in volume due to evaporation of water and become harder. As such, the seasonal moisture variation in such soil deposits around and beneath the structure results into subsequent upward and downward movements of structures leading to structural damage, in the form of wide cracks in the wall and distortion of floors. For identification and classification of expansive soils parameters like liquid limit, plasticity index, shrinkage limit, free swell, free swell index, linear shrinkage, swelling potential, swelling pressure and volume change from air dry to saturate condition should be evaluated experimentally or from available geotechnical correlation. Various recommended criteria for identification and classification of expansive soils are presented in Appendix E.
### **3.5.6 Identification and Classification of Collapsible Soils**
Soil deposits most likely to collapse are; (i) loose fills, (ii) altered wind-blown sands, (iii) hill wash of loose consistency and (iv) decomposed granite or other acid igneous rocks.
A very simple test for recognizing collapsible soil is the ″sauges test″. Two undisturbed cylindrical samples (sausages) of the same diameter and length (volume) are carved from the soil. One sample is then wetted and kneaded to form a cylinder of the original diameter. A decrease in length as compared to the original, undisturbed cylinder will confirm a collapsible grain structure. Collapse is probable when the natural void ratio, collapsible grain structure. Collapse is probable when the natural void ratio, P is higher than a critical void ratio, P+ that depends on void ratios PB and PA at liquid limit and plastic limits respectively. The following formula should be used to estimate the critical void ratio.
Collapsible soils (with a degree of saturation, C7 ≤ 0.6) should satisfy the following condition:
A consolidation test is to be performed on an undisturbed specimen at natural moisture content and to record the thickness, “H” on consolidation under a pressure “p” equal to overburden pressure plus the external pressure likely to be exerted on the soil. The specimen is then submerged under the same pressure and the final thickness H’ recorded. Relative subsidence, .D4 is found as:
Soils having .D4 ≥ 0.02 are considered to be collapsible.
### **3.5.7 Identification and Classification of Dispersive Soils**
Dispersive nature of a soil is a measure of erosion. Dispersive soil is due to the dispersed structure of a soil matrix. An identification of dispersive soils can be made on the basis of pinhole test.
The pinhole test was developed to directly measure dispersive potential of compacted fine grained soils in which water is made to flow through a small hole in a soil specimen, where water flow through the pinhole simulates water flow through a crack or other concentrated leakage channel in the impervious core of a dam or other structure. The test is run under 50, 180, 380 and 1020 mm heads and the soil is classified as follows in Table 6.3.4.
**Table 6.3.4: Classification of Dispersive Soil on the Basis of Pinhole Test (Sherard et. al. 1976)**
| **Test Observation** | **Type of Soil** | **Class of Soil** |
| ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------- | ----------------- |
| Fails rapidly under 50 mm head. | Dispersive soils | D1and D2 |
| Erode slowly under 50 mm or 180 mm head | Intermediate soils | ND4and ND3 |
| No colloidal erosion under 380 mm or 1020 mm head | Non-dispersive soils | ND2and ND1 |
| Another method of identification is to first determine the pH of a 1:2.5 soil/water suspension. If the pH is above 7.8, the soil may contain enough sodium to disperse the mass. Then determine: (i) total excahangable bases, that is, $K^+$, $Ca^{2+}$, $Mg^{2+}$ and Na+ (milliequivalent per 100g of air dried soil) and (ii) cation exchange capacity (CEC) of soil (milliequivalent per 100g of air dried soil). The Exchangeable Sodium Percentage ESP is calculated from the relation: | | |
$$
ESP = \frac{N_a}{CEC} \times 100(\%) \tag{6.3.4}
$$
$EM_gP$ is given by:
$$
EM_gP = \frac{Mg}{CEC} \times 100(\%) \tag{6.3.5}
$$
If the $ESP$ is above 8 percent and $ESP$ plus $EM_gP$ is above 15, dispersion will take place. The soils with $ESP$ = 7 to 10 are moderately dispersive in combination with reservoir waters of low dissolved salts. Soils with $ESP$ greater than 15 have serious piping potential. Dispersive soils do not actually present any problems with building structures. However, dispersive soil can lead to catastrophic failures of earth embankment dams as well as severe distress of road embankments.
### **3.5.8 Identification and Classification of Soft Inorganic Soils**
No standard definition exists for soft clays in terms of conventional soil parameters, mineralogy or geological origin. It is, however, commonly understood that soft clays give shear strength, compressibility and severe time related settlement problems. In near surface clays, where form a crust, partial saturation and overconsolidation occur together and the overconsolidation is a result of the drying out of the clay due to changes in water table.
In below surface clays, overconsolidation may have taken place when the clay was previously at, or close to the ground surface and above the water table, but due to subsequent deposition the strata may now be below the surface, saturated and overconsolidated. Partial saturation does not in itself cause engineering problems, but may lead to laboratory testing difficulties. Soft clays have undrained shear strengths between about 10kPa and 40kPa, in other words, from exuding between the fingers when squeezed to being easily moulded in the fingers.
Soft clays present very special problems of engineering design and construction. Foundation failures in soft clays are comparatively common. The construction of buildings in soft clays has always been associated with stability problems and settlement. Shallow foundations inevitably results in large settlements which must be accommodated for in the design, and which invariably necessitate long-term maintenance of engineered facilities. The following relationship among N-values obtained from SPT, consistency and undrained shear strength of soft clays may be used as guides.
| **N-value** | **Consistency** | **Undrained Shear Strength (kN/m****2****)** |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------- | ------------------------------------------------------- |
| Below 2 | Very soft | Less than 20 |
| 2 – 4 | Soft | 20 – 40 |
| Undrained shear strength is half of unconfined compressive strength as determined from unconfined compression test or half of the peak deviator stress as obtained from unconsolidated undrained (UU) triaxial compression test. | | |
## **3.6 Materials**
All materials for the construction of foundations shall conform to the requirements of Part 5 of this Code.
### **3.6.1 Concrete**
All concrete materials and steel reinforcement used in foundations shall conform to the requirements specified in Chapter 5 unless otherwise specified in this Section. For different types of foundation the recommended concrete properties are shown in Table 6.3.5. However, special considerations should be given for hostile environment (salinity, acidic environment).
**Table 6.3.5: Properties of Concrete for Different Types of Foundations**
| **Foundation Type** | **Minimum cement**
**content (kg/m****3****)** | **Specified Min.**
**28 days Cylinder**
**Strength (MPa)** | **Slump**
**(mm)** | **Remarks** |
| ------------------- | -------------------------------------------------------------- | -------------------------------------------------------------------- | ----------------------- | -------------------------------- |
| Footing/raft | 350 | 20 | 25 to 125 | Retarder and |
| | | | | plasticizer |
| Drilled shaft/Cast- | | | | |
| in-situ pile | 400 | 18 | 125 to 200 | recommended. |
| (tremie concrete) | | | | Slump test shall be |
| Driven pile | 350 | 25 | 25 to 125 | performed as per
ASTM C143. |
### **3.6.2 Steel**
All steel reinforcement and steel materials used in foundations shall conform to the requirements specified in Chapter 5 unless otherwise specified in this Section. However, this Section considers the corrosivity of soil that is described as under.
Corrosion in soil, water or moist out-door environment is caused by electro-chemical processes. The process takes place in corrosion cells on the steel surface, which consists of an anodic surface, a cathodic surface (where oxygen is reduced) and the electrolyte, which reacts with these surfaces. In the case of general corrosion, the surface erosion is relatively even across the entire surface. Local corrosion however is concentrated to a limited surface area. Pronounced cavity erosion is rather unusual on unprotected carbon steel in soil or water.
In many circumstances, steel corrosion rates are low and steel piles may be used for permanent works in an unprotected condition. The degree of corrosion and whether protection is required depend upon the working environment which can be variable, even within a single installation. Underground corrosion of steel piles driven into undisturbed soils is negligible irrespective of the soi1 type and characteristics. The insignificant corrosion attack is attributed to the low oxygen levels present in undisturbed soil. For the purpose of calculations, a maximum corrosion rate of 0.015
mm per side per year may be used. In recent-fill soils or industrial waste soils, where corrosion rates may be higher, protection systems should be considered.
* (a) Atmospheric Corrosion
Atmospheric corrosion of steel of 0.035 mm/side per year may be used for most atmospheric environments.
* (b) Corrosion in Fresh Water
Corrosion losses in fresh water immersion zones are generally lower than for sea water so the effective life of steel piles is normally proportionately longer. However, fresh waters are variable and no general advice can be given to quantify the increase in the length of life.
* (c) Corrosion in Marine Environment
Marine environments may include several exposure zones with different aggressivity and different corrosion performance.
* (i) Below the bed level: Where piles are below the bed level little corrosion occurs and the corrosion rate given for underground corrosion is applicable, that is, 0.015 mm/side per year.
* (ii) Seawater immersion zone: Corrosion of steel pilling in immersion conditions is normally low, with a mean corrosion rate of 0.035 mm/side per year.
* (iii) Tidal zones: Marine growths in this zone give significant protection to the piling, by sheltering the steel from wave action between tides and by limiting the oxygen supply to the steel surface. The corrosion rate of steels in the tidal zone is similar to that of immersion zone corrosion, i.e. 0.035 mm/side per year. Protection should be provided where necessary, to the steel surfaces to prevent the removal or damage of the marine growth.
* (iv) Low water zone: In tidal waters, the low water level and the splash zone are reasons of highest thickness losses, where a mean corrosion rate of 0.075 mm/side per year occurs. Occasionally higher corrosion rates are encountered at the lower water level because of specific local conditions.
* (v) Splash and atmospheric zones: In the splash zone, which is a more aggressive environment than the atmospheric zone, corrosion rates are similar to the low water level, i.e. 0.075 mm/side per year. In this zone thick stratified rust layers may develop and at thicknesses greater than 10 mm this tend to spall from steel especially on curved parts of the piles such as the shoulders and the clutches. Rust has a much greater volume than the steel from which it is derived so that the steel corrosion losses are represented by some 10 % to 20 % of the rust thickness. The boundary between splash and atmospheric zones is not well defined, however, corrosion rates diminish rapidly with distance above peak wave height and mean atmospheric corrosion rate of 0.035 mm/side per year can be used.
* (d) Method of Assessing Soil Corrosivity
The following variables attributes to accelerated corrosion: (i) acidity and alkalinity; (ii) soluable salts; (iii) bacteria (sulphates usually promote bacteria; (iv) resistivity; (v) moisture content; (vi) pH; and so on. The following charts, Tables 6.3.6a and 6.3.6b provide guides in assessing the corrosivity of soils. The parameters should be measured following relevant Standards of ASTM.
**Table 6.3.6a: Soil Corrosivity Scores for Various Parameters**
| **Item/Parameter** | **Measured value** | **Score/Mark** |
| ----------------------------------------- | ------------------------------------------------------------------ | -------------- |
| Soil composition | Calcareous, marly limestone, sandy marl, non-
stratified sand | +2 |
| | Sandy silt, sandy clay, clayey silt | 0 |
| | Clay, silty clay | -2 |
| | Peat, marshy soil | -4 |
| Ground water | None | 0 |
| | Exist | -1 |
| | Vary | -2 |
| Resistivity | 10,000 ohm-cm or more | 0 |
| | 10,000-5,000 | -1 |
| | 5,000-2,300 | -2 |
| | 2,300-1,000 | -3 |
| | 1,000 or less | -4 |
| Moisture content | 20% or less | 0 |
| | More than 20% | -1 |
| pH | 6 or more | 0 |
| | Less than 6 | -2 |
| Sulphide and hydrogen | None | 0 |
| sulphide | | |
| | Trace | -2 |
| | Exist | -4 |
| Carbonate | 5% or more | +2 |
| | 5% - 1% | +1 |
| | Less than 1% | 0 |
| Chloride | 100 mg/kg or less | 0 |
| | More than 100 mg/kg | +1 |
| Sulphate | 200 mg/kg or less | 0 |
| | 200 – 500 mg/kg | -1 |
| | 500 – 1000 mg/kg | -2 |
| | More than 1000 mg/kg | -3 |
| Cinder and coke | None | 0 |
| | Exist | -4 |
| **Table 6.3.6b: Soil Corrosivity Rating** | | |
| **Score/Mark** | **Corrosivity Rating** |
| -------------- | ---------------------- |
| 0 and above | Non-corrosive |
| 0 to -4 | Slightly corrosive |
| -5 to -10 | Corrosive |
| -10 or less | Highly corrosive |
* (e) Methods of Increasing Effective Life
The effective life of unpainted or otherwise unprotected steel piling depends upon the combined effects of imposed stresses and corrosion. Where measures for increasing the effective life of a structure are necessary, the following should be considered; introduction of a corrosion allowance (i.e. oversized cross-sections of piles, high yield steel etc), anticorrosion painting, application of a polyethylene (PE) coating (on steel tube piles), zinc coating, electro-chemical (cathodic) protection, casting in cement mortar or concrete, and use of atmospheric corrosion resistant steel products instead of ordinary carbon steel in any foundation work involving steel.
* (i) Use of a heavier section: Effective life may be increased by the use of additional steel thickness as a corrosion allowance. Maximum corrosion seldom occurs at the same position as the maximum bending moment. Accordingly, the use of a corrosion allowance is a cost effective method of increasing effective life. It is preferable to use atmospheric corrosion resistant high strength low alloy steel.
* (ii) Use of a high yield steel: An alternative to using mild steel in a heavier section is to use a higher yield steel and retain the same section.
* (iii) Zinc coatings: Steel piles should normally be coated under shop conditions. Paints should be applied to the cleaned surface by airless spraying and then cured rapidly to produce the required coating thickness in as few coats as possible. Hot zinc-coating of steel piles in soil can achieve normally long-lasting protection, provided that the zinc layer has sufficient thickness. In some soils, especially those with low pH-values, the corrosion of zinc can be high, thereby shortening the protection duration. Low pH-values occur normally in the aerated zone above the lowest ground water level. In such a case, it is recommended to apply protection paint on top of the zinc layer.
* (iv) Concrete encasement: Concrete encasement may be used to protect steel piles in marine environment. The use of concrete may be restricted to the splash zone by extending the concrete cope to below the mean high water level, both splash and tidal zones may be protected by extending the cope to below the lowest water level. The concrete itself should be a quantity sufficient to resist seawater attack.
* (v) Cathodic protection: The design and application of cathodic protection systems to marine piles structures is a complex operation requiring the experience of specialist firms. Cathodic protection with electric current applied to steel sheet pile wall. Rod-type anodes are connected directly with steel sheet pile. Cathodic protection is considered to be fully effective only up to the half-tide mark. For zones above this level, including the splash zone, alternative methods of protection may be required, in addition to cathodic protection. Where cathodic protection is used on marine structures, provision should be made for earthing ships and buried services to the quay.
* (vi) Polyetheline coating: Steel tube piles can be protected effectively by application of a PE-cover of a few millimeter of thickness. This cover can be applied in the factory and is usually placed on a coating of epoxy. Steel tube piles in water, where the mechanical wear is low, can in this way be protected for long time periods. When the steel tube piles with the PE-cover are driven into coarsegrained soil, the effect of damaging the protection layer must be taken into consideration.
* (vii) Properly executed anti-corrosion measures, using high-quality methods can protect steel piles in soil or water over periods of 15 to 20 years. PE-cover in combination with epoxy coating can achieve even longer protection times.
### **3.6.3 Timber**
Timber may be used only for foundation of temporary structure and shall conform to the standards specified in Sec 2.9 of Part 5 of this Code. Where timber is exposed to soil or used as load bearing pile above ground water level, it shall be treated in accordance with BDS 819:1975.
## **3.7 Types of Foundation**
### **3.7.1 Shallow Foundations**
Shallow foundations spread the load to the ground at shallow depth. Generally, the capacity of this foundation is derived from bearing.
### **3.7.2 Footing**
Footings are foundations that spread the load to the ground at shallow depths. These include individual column footings, continuous wall footings, and combined footings. Footings shall be provided under walls, pilasters, columns, piers, chimneys etc. bearing on soil or rock, except that footings may be omitted under pier or monolithic concrete walls if safe bearing capacity of the soil or rock is not exceeded.
### **3.7.3 Raft/Mat**
A foundation consisting of continuous slab that covers the entire area beneath the structure and supports all walls and columns is considered as a raft or mat foundation. A raft foundation may be one of the following types:
* (i) Flat plate or concrete slab of uniform thickness usually supporting columns spaced uniformly and resting on soils of low compressibility.
* (ii) Flat plates as in (a) but thickened under columns to provide adequate shear and moment resistance.
* (iii) Two way slab and beam system supporting largely spaced columns on compressible soil.
* (iv) Cellular raft or rigid frames consisting of slabs and basement walls, usually used for heavy structures.
### **3.7.4 Deep Foundations**
A cylindrical/box foundation having a ratio of depth to base width greater than 5 is considered a Deep Foundation. Generally, its capacity is derived from friction and end bearing.
### **3.7.5 Driven Piles**
A slender deep foundation unit made of materials such as steel, concrete, wood, or combination thereof, which is pre-manufactured and placed by driving, jacking, jetting or screwing and displacing the soil.
* (i) Driven Precast Concrete Piles: Pile structure capable of being driven into the ground and able to resist handling stresses shall be used for this category of piles.
* (ii) Driven Cast-in-situ Concrete Piles : A pile formed by driving a steel casing or concrete shell in one or more pieces, which may remain in place after driving or withdrawn, with the inside filled with concrete, falls in this category of piles. Sometimes an enlarged base may be formed by driving out a concrete plug.
* (iii) Driven Prestressed Concrete Pile: A pile constructed in prestressed concrete in a casting yard and subsequently driven in the ground when it has attained sufficient strength.
* (iv) Timber Piles: Structural timber (Sec 2.9 Part 5) shall be used as piles for temporary structures for directly transmitting the imposed load to soil. Driven timber poles are used to compact and improve the deposit.
### **3.7.6 Bored Piles/Cast-in-Situ Piles**
A deep foundation of generally small diameter, usually less than 600 mm, constructed using percussion or rotary drilling into the soil. These are constructed by concreting bore holes formed by auguring, rotary drilling or percussion drilling with or without using bentonite mud circulation. Excavation or drilling shall be carried out in a manner that will not impair the carrying capacity of the foundations already in place or will not damage adjacent foundations. These foundations may be tested for capacity by load test or for integrity by sonic response or other suitable method. Under-reaming drilled piers can be constructed in cohesive soils to increase the end bearing.
### **3.7.7 Drilled Pier/Drilled Shafts**
Drilled pier is a bored pile with larger diameter (more than 600 mm) constructed by excavating the soil or sinking the foundation.
### **3.7.8 Caisson/Well**
A caisson or well foundation is a deep foundation of large diameter relative to its length that is generally a hollow shaft or box which is sunk to position. It differs from other types of deep foundation in the sense that it undergoes rigid body movement under lateral load, whereas the others are flexible like a beam under such loads. This type of foundation is usually used for bridges and massive structures.
**Division B: Design of Foundations (Sections 3.8 to 3.11)**
## **3.8 Shallow Foundation**
This Section shall be applicable to isolated Footings, Combined Footings and Raft/Mats.
### **3.8.1 Distribution of Bearing Pressure**
Footing shall be designed to keep the maximum imposed load within the safe bearing values of soil and rock. To prevent unequal settlement footing shall be designed to keep the bearing pressure as nearly uniform as practical. For raft design, distribution of soil pressures should be consistent with the properties of the foundation materials (subsoil) and the structure (raft thickness) and with the principles of geotechnical engineering.
Mat or raft and floating foundations shall only be used when the applied load of building or structure is so arranged as to result in practically uniformly balanced loading, and the soil immediately below the mat is of uniform bearing capacity.
### **3.8.2 Dimension of Footings**
Footings shall generally be proportioned from the allowable bearing pressure and stress limitations imposed by limiting settlement.
The angle of spread of the load from the wall base to outer edge of the ground bearing shall not exceed the following:
1 Brick or stone masonry horizontal to 1 vertical Lime concrete horizontal to 1 vertical 2 Cement concrete 1 horizontal to 1 vertical
A footing shall be placed to depth so that:
* (a) adequate bearing capacity is achieved,
* (b) in case of clayey soil , shrinkage and swelling due to seasonal weather change is not significant,
* (c) it is below possible excavation close by, and
* (d) it is at least 500 mm below natural ground level unless rock or other weather resistant material is at the surface.
Where footings are to be founded on a slope, the distance of the sloping surface at the base level of the footing measured from the centre of the footing shall not be less than twice the width of the footing.
When adjacent footings are to be placed at different levels, the distance between the edges of footings shall be such as to prevent undesirable overlapping of structures in soil and disturbance of the soil under the higher footing due to excavation of the lower footing.
On a sloping site, footing shall be on a horizontal bearing and stepped. At all changes of levels, footings shall be lapped for a distance of at least equal to the thickness of foundation or three times the height of step, whichever is greater. Adequate precautions shall be taken to prevent tendency for the upper layers of soil to move downhill.
### **3.8.3 Thickness of Footing**
The minimum thickness for different types of footing for light structures (two stories or less in occupancy category A, B, C and D), shall be as follows:
| **Type of Footing** | **Minimum Thickness** | **Remark** |
| --------------------------------------- | ------------------------------------------------------------------------ | --------------------------------------------------------------- |
| Masonry | 250 mm; twice the maximum
projection from the face of the
wall | Greater of the two
values
shall
be
selected |
| Plain concrete | 200 mm, or twice the maximum
offset in a stepped footing | - |
| Reinforced concrete | 150 mm | Resting on soil |
| (depth above bottom
reinforcement) | 300 mm | Resting on pile |
### **3.8.4 Footings in Fill Soil**
Footings located in fill are subject to the same bearing capacity, settlement, and dynamic ground stability considerations as footings in natural soil. The behavior of both fill and underlying natural soil should be considered.
### **3.8.5 Soil and Rock Property Selection**
Soil and rock properties defining the strength and compressibility characteristics of foundation materials are required for footing design. Foundation stability and settlement analysis for design shall be conducted using soil and rock properties based on the results of field and laboratory testing.
### **3.8.6 Minimum Depth of Foundation**
The minimum depth of foundation shall be 1.5 m for exterior footing of permanent structures in cohesive soils and 2 m in cohesionless soils. For temporary structures the minimum depth of exterior footing shall be 400 mm. In case of expansive and soils susceptible to weathering effects, the above mentioned minimum depths will be not applicable and may have to be increased.
### **3.8.7 Scour**
Footings supported on soil shall be embedded sufficiently below the maximum computed scour depth or protected with a scour countermeasure.
### **3.8.8 Mass Movement of Ground in Unstable Areas**
In certain areas mass movement of ground may occur from causes independent of the loads applied to the foundation. These include mining subsidence, landslides on unstable slopes and creep on clay slopes. In areas of ground subsidence, foundations and structures should be made sufficiently rigid and strong to withstand the probable worst loading conditions. The construction of structures on slopes which are suspected of being unstable and subject to landslip shall be avoided. Spread foundations on such slopes shall be on a horizontal bearing and stepped. For foundations on clay slopes, the stability of the foundation should be investigated.
### **3.8.9 Foundation Excavation**
Foundation excavation below ground water table particularly in sand shall be made such that the hydraulic gradient at the bottom of the excavation is not increased to a magnitude that would case the foundation soils to loosen due to upward flow of water. Further, footing excavations shall be made such that hydraulic gradients and material removal do not adversely affect adjacent structures. Seepage forces and gradients may be evaluated by standard flow net procedures. Dewatering or cutoff methods to control seepage shall be used when necessary. In case of soil excavation for raft foundations, the following issues should be additionally taken into consideration:
* (i) Protection for the excavation using shore or sheet piles and/or retaining system with or without bracing, anchors etc.
* (ii) Consideration of the additional bearing capacity of the raft for the depth of the soil excavated.
* (iii) Consideration of the reduction of bearing capacity for any upward buoyancy pressure of water.
* (iv) Other considerations as mentioned in Sec 3.12.
### **3.8.10 Design Considerations for Raft foundation**
Design provisions given in Sec 3.9.2 shall generally apply. In case the raft supports structure consisting of several parts with varying loads and height, it is advisable to provide separate joints between these parts. Joints shall also be provided wherever there is a change in the direction of the raft. The minimum depth of foundation shall generally be not less than 1.5 m in cohesive soil and 2 m in cohesionless soils. Foundations subject to heavy vibratory loads shall preferably be isolated.
#### 3.8.10.1 Dimensioning
The size and shape of the foundation shall be decided taking into consideration the magnitude of subgrade modulus, the long term deformation of the supporting soil and the distribution of contact pressure.
Distribution of contact pressure underneath a raft is affected by the physical characteristics of the supporting soil. Consideration shall be given to the increased contact pressure developed along the edges of foundation on cohesive soils and the decrease in pressure on granular soils. Both long term and short term deformation and settlement effects shall be considered in the design.
#### 3.8.10.2 Eccentricity
Since raft foundation usually occupies the entire area of a building, it may not be feasible to proportion the raft so that the centroid of the raft coincides with the line of action of the resultant force due to building. In such cases, the effect of eccentricity on the contact pressure distribution shall be considered in the design.
#### 3.8.10.3 Rigidity of Foundation
The rigidity of foundation affects soil pressure distribution which in turn produces additional stresses in the raft due to moments etc. A rigid foundation also generates high secondary stresses. The effects of such rigidity shall be taken into consideration in designing rafts.
#### 3.8.10.4 Methods of Analysis
The essential part of analysis of a raft foundation is the determination of distribution of contact pressure below the mat which is a complex function of the rigidity of raft, and the rigidity of the superstructure and the supporting soil. Any analytical method shall therefore use simplifying assumptions which are reasonably valid for the condition analysed. Choice of a particular method shall therefore be governed by the validity of the assumptions in the particular case.
## **3.9 Geotechnical Design of Shallow Foundations**
### **3.9.1 General**
Shallow foundations on soil shall be designed to support the design loads with adequate bearing and structural capacity and with tolerable settlements. In addition, the capacity of footings subjected to seismic and dynamic loads shall be appropriately evaluated. The location of the resultant pressure on the base of the footings should be maintained preferably within B/6 of the centre of the footing.
### **3.9.2 Design Load**
* (a) Shallow foundation design considering bearing capacity due to shear strength shall consider the most unfavourable effect of the following combinations of loading:
* (i) Full Dead Load + Normal Live Load
* (ii) Full Dead Load + Normal Live Load + Wind Load or Seismic Load
* (iii) 0.9 ×(Full Dead Load) + Buoyancy Pressure
* (b) Shallow foundation design considering settlement shall consider the most unfavourable effect of the following combinations of loading:
**SAND**
* (i) Full Dead Load + Normal Live Load
* (ii) Full Dead Load + Normal Live Load + Wind Load or Seismic Load
**CLAY**
Full Dead Load + 0.5× Normal Live Load
Normal Live Load is a live load considering floor area reduction factor as used in column design (Sec 2.3.13).
### **3.9.3 Bearing Capacity of Shallow Foundations**
When physical characteristics such as cohesion, angle of internal friction, density etc. are available, the bearing capacity shall be calculated from stability considerations. Established bearing capacity equations shall be used for calculating bearing capacity.
A factor of safety of between 2.0 to 3.0 (depending on engineering judgement on the extent of soil exploration, quality control and monitoring of construction) shall be adopted to obtain allowable bearing pressure when dead load and normal live load is used. Thirty three percent (33%) overstressing above allowable pressure shall be allowed in case of design considering wind or seismic loading. Allowable load shall also limit settlement between supporting elements to a tolerable limit **.**
#### 3.9.3.1 Presumptive bearing capacity for preliminary design
For lightly loaded and small sized structures (two storied or less in occupancy category A, B, C & D) and for preliminary design of any structure, the presumptive bearing values (allowable) as given in Table 6.3.7 may be assumed for uniform soil in the absence of test results.
#### 3.9.3.2 Allowable increase of bearing pressure due to wind and earthquake forces
The allowable bearing pressure of the soil determined in accordance with this Section may be increased by 33 percent when lateral forces due to wind or earthquake act simultaneously with gravity loads. No increase in allowable bearing pressure shall be permitted for gravity loads acting alone. In a zone where seismic forces exist, possibility of liquefaction in loose sand, silt and sandy soils shall be investigated.
**Table 6.3.7: Presumptive Values of Bearing Capacity for Lightly Loaded Structures**\*
| **Soil** | **Soil Description** | **Safe Bearing** |
| -------- | ------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------ |
| **Type** | | **Capacity, kPa** |
| 1 | Soft Rock or Shale | 440 |
| 2 | Gravel, sandy gravel, silty sandy gravel; very dense and
offer high resistance to penetration during excavation (soil | 400\*\* |
| | shall include the groups GW, GP, GM, GC) | |
| 3 | Sand (other than fine sand), gravelly sand, silty sand; dry
(soil shall include the groups SW, SP, SM, SC) | 200\*\* |
| 4 | Fine sand; loose & dry (soil shall include the groups SW, SP) | 100\*\* |
| 5 | Silt, clayey silt, clayey sand; dry lumps which can be
easily crushed by finger (soil shall include the groups
ML, SC & MH) | 150 |
| 6 | Clay, sandy clay; can be indented with strong thumb
pressure (soil shall include the groups CL & CH) | 150 |
| 7 | Soft clay; can be indented with modest thumb pressure
(soil shall include the groups CL & CH) | 100 |
| 8 | Very soft clay; can be penetrated several centimeters with
thumb pressure (soil shall include the groups CL & CH) | 50 |
| 9 | Organic clay & Peat (soil shall include the groups
OH, OL, Pt) | To be determined
after investigation. |
| 10 | Fills | To be determined
after investigation. |
* Two stories or less (Occupancy category A, B, C and D)
* \*\* 50% of these values shall be used where water table is above the base, or below it within a distance equal to the least dimension of foundation
### **3.9.4 Settlement of Shallow Foundation**
Foundation shall be so designed that the allowable bearing capacity is not exceeded, and the total and differential settlement are within permissible values. Foundations can settle in various ways and each affects the performance of the structure. The simplest mode consists of the entire structure settling uniformly. This mode does not distort the structure. Any damage done is related to the interface between the structure and adjacent ground or adjacent structures. Shearing of utility lines could be a problem. Another possibility is that one side of the structure settles much more than the opposite side and the portions in between settle proportionately. This causes the structure to tilt, but it still does not distort. A nominal tilt will not affect the performance of the structure, although it may create aesthetic and public confidence problems. However, as a result of difference in foundation settlement the structure may settle and distort causing cracks in walls and floors, jamming of doors and windows and overloading of structural members.
#### 3.9.4.1 Total settlement
Total settlement () is the absolute vertical movement of the foundation from its asconstructed position to its loaded position. Total settlement of foundation due to net imposed load shall be estimated in accordance with established engineering principle. An estimate of settlement with respect to the following shall be made.
* (i) Elastic compression of the underlying soil below the foundation and of the foundation.
* (ii) Consolidation settlement.
* (iii) Secondary consolidation/compression of the underlying soil.
* (iv) Compression and volume change due to change in effective stress or soil migration associated with lowering or movement of ground water.
* (v) Seasonal swelling and shrinkage of expansive clays.
* (vi) Ground movement on earth slopes, such as surface erosion, creep or landslide.
* (vii) Settlement due to adjacent excavation, mining subsidence and underground erosion.
In normal circumstances of inorganic and organic soil deposits the total settlement is attributed due to the first three factors as mentioned above. The other factors are regarded as special cases. Because soil settlement can have both time-depended and notime-dependent components, it is often categorized in terms short-term settlement (or immediate settlement) which occurs as quickly as the load is applied, and longterm settlement (or delayed settlement), which occurs over some longer period. Many engineers associate consolidation settlement solely with the long term settlement of clay. However, this is not strictly true. Consolidation is related to volume change due to change in effective stress regardless of the type of soil or the time required for the volume change.
#### 3.9.4.2 Elastic/distortion settlement
Elastic Settlement \< of foundation soils results from lateral movements of the soil without volume change in response to changes in effective vertical stress. This is non-time dependent phenomenon and similar to the Poisson’s effect where an object is loaded in the vertical direction expands laterally. Elastic or distortion settlements primarily occur when the load is confined to a small area, such as a structural foundation, or near the edges of large loaded area such as embankments.
#### 3.9.4.3 Immediate settlement/short term settlement
This vertical compression occurs immediately after the application of loading either on account of elastic behaviour that produces distortion at constant volume and on account of compression of air void. This is sometimes designated as for sandy soil, even the consolidation component is immediate.
#### 3.9.4.4 Primary consolidation settlement
Primary consolidation settlement or simply the consolidation settlement + of foundation is due to consolidation of the underlying saturated or nearly saturated soil especially cohesive silt or clay. The full deal load and 50% of total live load shall be considered when computing the consolidation settlement of foundations on clay soils.
#### 3.9.4.5 Secondary consolidation settlement
Secondary consolidation settlement of the foundation is due to secondary compression or consolidation of the underlying saturated or nearly saturated cohesive silt or clay. This is primarily due to particle re-orientation, creep, and decomposition of organic materials. Secondary compression is always time-dependent and can be significant in highly plastic clays, organic soils, and sanitary landfills, but it is negligible in sands and gravels.
#### 3.9.4.6 Differential settlement
Differential settlement is the difference in total settlement between two foundations or two points in the same foundation. It occurs as a result of relative movement between two parts of a building. The related terms describing the effects of differential settlement on the structural as a whole or on parts of it are tilt, rotation and angular distortion/relative rotation which are defined below. Due consideration shall be given to estimate the differential settlement that may occur under the building structure under the following circumstances:
* (i) Non-uniformity in subsoil formation within the area covered by the building due to geologic or man-made causes, or anomalies in type, structure, thickness and density of the formation.
* (ii) Non-uniform pressure distribution due to non-uniform and incomplete loading.
* (iii) Ground water condition during and after construction.
* (iv) Loading influence of adjacent structures.
* (v) Uneven expansion and contraction due to moisture migration, uneven drying, wetting or softening.
#### 3.9.4.7 Rotation and tilt of shallow foundation
* (a) Rotation
Rotation is the angle between the horizontal line and an imaginary straight line connecting any two foundations or two points in a single foundation.
* (b) Tilt
Tilt is rotation of the entire superstructure or a well-defined part of it as a result of non-uniform or differential settlement of foundation as a result of which one side of the building settles more than the other thus affecting the verticality of the building.
(Angular Distortion/Relative Rotation)
Angular distortion or relative rotation is the angle between imaginary straight line indicating the overall tilt of a structure and the imaginary connecting line indicating the inclination of a specific part of it. It is measured as the ratio of differential settlement to the distance between the two points.
* (d) Tolerable Settlement, Tilt and Rotation
Allowable or limiting settlement of a building structure will depend on the nature of the structure, the foundation and the soil. Different types of structures have varying degrees of tolerance to settlements and distortions. These variations depend on the type of construction, use of the structure, rigidity of the structure and the presence of sensitive finishes. As a general rule, a total settlement of 25 mm and a differential settlement of 20 mm between columns in most buildings shall be considered safe for buildings on isolated pad footings on sand for working load (un-factored). A total settlement of 40 mm and a differential settlement of 20 mm between columns shall be considered safe for buildings on isolated pad footings on clay soil for working load. Buildings on raft can usually tolerate greater total settlements. Limiting tolerance for distortion and deflections introduced in a structure is necessarily a subjective process, depending on the status of the building and any specific requirements for serviceability. The limiting values, given in Table 6.3.8 may be followed as guidelines.
**Table 6.3.8: Permissible Total Settlement, Differential Settlement and Angular Distortion (Tilt) for Shallow Foundations in Soils (in mm) (Adapted from NBCI, 2005)**
| **Type of**
**Structure** | **Sand** | **Iso**
**and Hard** | **lated Fo**
**Clay** | **undatio** | **ns**
**Plastic Cla** | **y** | **Sand** |
**and Hard C** | **Raft Foun**
**lay** | **dation**
| **Plastic Cla** | **y** |
| ------------------------------------------------------------------------------- | ------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------- | ------------------------------------------------------------------- | ---------------------------------------------------------- | --------------------------------------------------------------------------- | ------------------------------------------------------------------------ | ---------------------------------------------------- | --------------------------------------------------- | ----------------------------------------- | ---------------------------------- | ---------------------------------------------- | --------------------------------- |
| | **Maximum**
**Settlement** | **Differential**
**Settlement** | **Angular**
**Distortion** | **Maximum**
**Settlement** | **Differential**
**Settlement** | **Angular**
**Distortion** | **Maximum**
**Settlement** | **Differential**
**Settlement** | **Angular**
**Distortion** | **Maximum**
**Settlement** | **Differential**
**Settlement** | **Angular**
**Distortion** |
| **Steel Structure** | 50 | 0.0033 L | 1/300 | 50 | 0.0033 L | 1/300 | 75 | 0.0033 L | 1/300 | 100 | 0.0033 L | 1/300 |
| **RCC Structures** | 50 | 00015 L | 1/666 | 75 | 00015 L | 1/666 | 75 | 00021 L | 1/500 | 100 | 0002 L | 1/500 |
| **Multistoried Buildi** |
**ng** | . | | | . | | | . | | | . | |
| (a) RCC or steel | | | | | | | | | | | | |
| framed
building with | 60 | 0.002 L | 1/500 | 75 | 0.002 L | 1/500 | 75 | 0.0025 L | 1/400 | 125 | 0.0033 L | 1/300 |
|
panel walls
(b) Load bearing wal | ls | | | | | | | | | | | |
| (i) L/H = 2 \* | 60 | 0.0002 L | 1/5000 | 60 | 0.0002 L | 1/5000 | | Not li | kely to be | encount | ered | |
| (ii) L/H = 7 \* | 60 | 0.0004 L | 1/2500 | 60 | 0.0004 L | 1/2500 | | Not li | kely to be | encount | ered | |
| **Silos** | 50 | 0.0015 L | 1/666 | 75 | 0.0015 L | 1/666 | 100 | 0.0025 L | 1/400 | 125 | 0.0025 L | 1/400 |
| **Water Tank** | 50 | 0.0015 L | 1/666 | 75 | 0.0015 L | 1/666 | 100 | 0.0025 L | 1/400 | 125 | 0.0025 L | 1/400 |
| Notes: The va
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### **3.9.5 Dynamic Ground Stability or Liquefaction Potential for Foundation Soils**
Soil liquefaction is a phenomenon in which a saturated soil deposit loses most, if not all, of its strength and stiffness due to the generation of excess pore water pressure during earthquake-induced ground shaking. It has been a major cause for damage of structures during past earthquakes (e.g., 1964 Niigata Earthquake). Current knowledge of liquefaction is significantly advanced and several evaluation methods are available. Hazards due to liquefaction are routinely evaluated and mitigated in seismically active developed parts of the world.
Liquefaction can be analyzed by a simple comparison of the seismically induced shear stress with the similarly expressed shear stress required to cause initial liquefaction or whatever level of shear strain amplitude is deemed intolerable in design. Usually, the occurrence of 5% double amplitude (DA) axial strain is adopted to define the cyclic strength consistent with 100% porewater pressure build-up. The corresponding strength (CRR) can be obtained by several procedures. Thus, the liquefaction potential of a sand deposit is evaluated in terms of factor of safety *FL* , defined as in Eq. 6.3.6.
$$
F_L = \frac{CRR}{CSR} \tag{6.3.6}
$$
The externally applied cyclic stress ratio (CSR) can be evaluated using Equations 6.3.7a, 6.3.7b and 6.3.8.
If the factor of safety $F_L$ is \< 1, liquefaction is said to take place. Otherwise, liquefaction does not occur. The factor of safety obtained in this way is generally used to identify the depth to which liquefaction is expected to occur in a future earthquake. This information is necessary if countermeasure is to be taken in an in situ deposit of sands.
The cyclic shear stress induced at any point in level ground during an earthquake due to the upward propagation of shear waves can be assessed by means of a simple procedure proposed. If a soil column to a depth *z* is assumed to move horizontally and if the peak horizontal acceleration on the ground surface is $a_{max}$ , the maximum shear stress $\tau_{max}$ acting at the bottom of the soil column is given by
$$
\tau_{max} = a_{max}r_d(\gamma_t)(z/g) \tag{6.3.7a}
$$
$$
r_d = 1 - 0.015z \tag{6.3.7b}
$$
Where, $\gamma_t$ is unit weight of the soil, $g$ is the gravitational acceleration, $z$ is the depth and $r_d$ is a stress reduction coefficient to allow for the deformability of the soil column ( $r_d$ \< 1). It is recommended to use the empirical formula given in Eq. 6.3.7b to compute stress reduction coefficient $r_d$, where $z$ is in meters. Division of both sides of Eq. 6.3.7a by the effective vertical stress $\sigma_v'$ gives
$$
CSR = \frac{\tau_{max}}{\sigma_v'} = \frac{a_{max}}{g}r_d\frac{\sigma_v}{\sigma_v'} \tag{6.3.8}
$$
Where, $\sigma_v = \gamma_tz$ is the total vertical stress. Eq. 6.3.8 has been used widely to assess the magnitude of shear stress induced in a soil element during an earthquake. The peak ground acceleration, $a_{max}$ should be taken from seismic zoning map. One of the advantages of Eq. 6.3.8 is that all the vast amount of information on the horizontal accelerations that has ever been recorded on the ground surface can be used directly to assess the shear stress induced by seismic shaking in the horizontal plane within the ground.
The second step is to determine the cyclic resistance ratio (CRR) of the in situ soil. The cyclic resistance ratio represents the liquefaction resistance of the in situ soil. The most commonly used method for determining the liquefaction resistance is to use the data obtained from the standard penetration test. A cyclic triaxial test may also be used to estimate CRR more accurately. Site response analysis of a site may be carried out to estimate the site amplification factor. For this purpose, dynamic parameters such as shear modulus and damping factors need to be estimated. The site amplification factor is required to estimate $a_{max}$ for a given site properly. The following points are to be noted as regards to soil liquefaction:
* Sandy and silty soils tend to liquefy; clay soils do not undergo liquefaction except the sensitive clays.
* Resistance to liquefaction of sandy soil depends on fine content. Higher the fine content lower is the liquefaction potential.
* As a rule of thumb, any soil that has a SPT value higher than 30 will not liquefy.
Fine grained soils (silty clays/ clayey silt) are susceptible to liquefaction if (Finn et. al., 1994):
* Fraction finer than 0.005 mm ≤ 10%
* Liquid limit (LL) ≤ 36%
* Natural water content ≤ 0.9 × LL
* Liquidity index ≤ 0.75
### **3.9.6 Structural Design of Shallow Foundations**
The foundation members should have enough strength to withstand the stresses induced from soil-foundation interaction. The following important factors should be considered in the structural design of foundations.
#### 3.9.6.1 Loads and reactions
Footings shall be considered as under the action of downward forces, due to the superimposed loads, resisted by an upward pressure exerted by the foundation materials and distributed over the area of the footings as determined by the eccentricity of the resultant of the downward forces. Where piles are used under footings, the upward reaction of the foundation shall be considered as a series of concentrated loads applied at the pile centers, each pile being assumed to carry the computed portion of the total footing load.
#### 3.9.6.2 Isolated and multiple footing reactions
When a single isolated footing supports a column, pier or wall, the footing shall be assumed to act as a cantilever element. When footings support more than one column, pier, or wall, the footing slab shall be designed for the actual conditions of continuity and restraint.
#### 3.9.6.3 Raft foundation reactions
For determining the distribution of contact pressure below a raft it is analyzed either as a rigid or flexible foundation considering the rigidity of the raft, and the rigidity of the superstructure and the supporting soil. Consideration shall be given to the increased contact pressure developed along the edges of raft on cohesive soils and the decrease in contact pressure along the edges on granular soils. Any appropriate analytical method reasonably valid for the condition may be used. Choice of a particular method shall be governed by the validity assumptions used. Numerical analysis of rafts using appropriate software may also be used for determination of reactions, shears and moments.
Both analytical (based on beams on elastic foundation, Eq. 6.3.9) and numerical methods require values of the modulus of subgrade reaction of the soil. For use in preliminary design, indicative values of the modulus of subgrade reaction ( *k* ) for cohesionless soils and cohesive soils are shown in Tables 6.3.9a and 6.3.9b, respectively.
Where, L= Modulus of elasticity of soil; LM = Flexural rigidity of foundation; N = Width of foundation; O = Poisson’s ratio of soil.
**Table 6.3.9a: Modulus of Subgrade Reaction** ***(k)* for Cohesionless Soils**
| | **Soil Characteristic** | \***Modulus of Sub-gr**
**(kN/m****3****)** | **ade Reaction\*\*\*\**(k)* of Soil** |
| -------------------------------------------------------------------------------- | -------------------------------------------------- | ----------------------------------------------------------- | ------------------------------------- |
| **Relative** | **Standard Penetration Test** | **For Dry or Moist** | **For Submerged** |
| **Density** | **Value\*\*\*\**(N)* (Blows per 300**
**mm)** | **State** | **State** |
| Loose | \<10 | 15000 | 9000 |
| Medium | 10 to 30 | 15000 to 47000 | 9000 to 29000 |
| Dense | 30 and over | 47000 to 180000 | 29000 to 108000 |
| \*The above values apply to a square plate 300 mm x 300 mm or beams 300 mm wide. | | | |
**Table 6.3.9b: Modulus of Subgrade Reaction** ***(k)* for Cohesive Soils**
| | **Soil Characteristic** | **Modulus of Subgrade** |
| --------------- | -------------------------------------------------------------- | ---------------------------------------------------- |
| **Consistency** | **Unconfined Compressive Strength (kN/m****2****)** | **Reaction\*\*\*\**, k* (kN/m****3****)** |
| Stiff | 100 to 200 | 27000 |
| Very Stiff | 200 to 400 | 27000 to 54000 |
| Hard | 400 and over | 54000 to 108000 |
* The values apply to a square plate 300 mm x 300 mm. The above values are based on the assumption that the average loading intensity does not exceed half the ultimate bearing capacity.
#### 3.9.6.4 Critical section for moment
External moment on any section of a footing shall be determined by passing a vertical plane through the footing and computing the moment of the forces acting over the entire area of the footing on one side of that vertical plane. The critical section for bending shall be taken at the face of the column, pier, or wall. In the case of columns that are not square or rectangular, the section shall be taken at the side of the concentric square of equivalent area. For footings under masonry walls, the critical section shall be taken halfway between the middle and edge of the wall. For footings under metallic column bases, the critical section shall be taken halfway between the column face and the edge of the metallic base. For mat foundations and combined footings critical section should be determined on the basis of maximum positive and negative moments obtained from soil-foundation interaction.
#### 3.9.6.5 Critical section for shear
Computation of shear in footings, and location of critical section shall be in accordance with relevant sections of the structural design part of the Code. Location of critical section shall be measured from the face of column, pier or wall, for footings supporting a column, pier, or wall. For footings supporting a column or pier with metallic base plates, the critical section shall be measured from the location defined in the critical section for moments for footings.
#### 3.9.6.6 Critical section for footings on driven piles/bored piles/drilled piers
Shear on the critical section shall be in accordance with the following. Entire reaction from any driven pile or bored piles, and drilled pier whose center is located !/2 (! = diameter of the pile) or more outside the critical section shall be considered as producing shear on that section. Reaction from any driven pile or drilled shaft whose center is located !/2 or more inside the critical section shall be considered as producing no shear on that section. For the intermediate position of driven pile or
drilled shaft centers, the portion of the driven pile or shaft reaction to be considered as producing shear on the critical section shall be based on linear interpolation between full value at !/2 outside the section and zero value at !/2 inside the section.
#### 3.9.6.7 Transfer of Forces at the Base of Column.
All forces and moments applied at base of column or pier shall be transferred to top of footing. If the strength of concrete of footing is less than that of column, then bearing stress of footing concrete and reinforcement should be checked against imposed loading.
Lateral forces shall be transferred to supporting footing in accordance with shear transfer provisions of the relevant sections of the structural design part of the Code.
Bearing on concrete at contact surface between supporting and supported member shall not exceed concrete bearing strength for either surface.
#### 3.9.6.8 Reinforcement
Reinforcement shall be provided across interface between supporting and supported member either by extending main longitudinal reinforcement into footings or by dowels. Reinforcement across interface shall be sufficient to satisfy all of the following:
* (i) Reinforcement shall be provided to transfer all force that exceeds concrete bearing strength in supporting and supported member.
* (ii) If it is required that loading conditions include uplift, total tensile force shall be resisted by reinforcement only.
* (iii) Area of reinforcement shall not be less than 0.005 times gross area of supported member (column) with a minimum of 4 bars.
* (iv) Minimum reinforcement of footing and raft shall be governed by temperature and shrinkage reinforcement as per Sec 8.1.11 Chapter 8 of this Part.
Reinforcement of square footings shall be distributed uniformly across the entire width of footing. Reinforcement of rectangular footings shall be distributed uniformly across the entire width of footing in the long direction. In the short direction, the portion of the total reinforcement given by the following equation shall be distributed uniformly over a band width (centered on center line of column or pier) equal to the length of the short side of the footing.
Here, c is the ratio of the footing length to width. The remainder of reinforcement required in the short direction shall be distributed uniformly outside the center band width of footing.
#### 3.9.6.9 Development length and splicing
Computation of development length of reinforcement in footings shall be in accordance with the relevant sections of the structural design part of the Code.
For transfer of force by reinforcement, development length of reinforcement in supporting and supported member required splicing shall be in accordance with the relevant sections (Part. 6, Chapters 6 and 8) of the structural design part of the Code. Critical sections for development length of reinforcement shall be assumed at the same locations as defined above as the critical section for moments and at all other vertical planes where changes in section or reinforcement occur.
#### 3.9.6.10 Dowel size
Diameter of dowels, if used, shall not exceed the diameter of longitudinal reinforcements.
## **3.10 Geotechnical Design of Deep Foundations**
### **3.10.1 Driven Precast Piles**
The provisions of this article shall apply to the design of axially and laterally loaded driven piles in soil. Driven pile foundation shall be designed and installed on the basis of a site investigation report that will include subsurface exploration at locations and depths sufficient to determine the position and adequacy of the bearing soil unless adequate data is available upon which the design and installation of the piles can be based. The report shall include:
* (i) Recommended pile type and capacities
* (ii) Driving and installation procedure
* (iii) Field inspection procedure
* (iv) Requirement of pile load test
* (v) Durability and quality of pile material
* (vi) Designation of bearing stratum or strata
A plan showing clearly the designation of all piles by an identifying system shall be filed prior to installation of such piles. All detailed records for individual piles shall bear an identification corresponding to that shown on the plan. A copy of such plan shall be available at the site for inspection at all times during the construction.
The design and installation of driven pile foundations shall be under the direct supervision of a competent geotechnical/foundation engineer who shall certify that the piles as installed satisfy the design criteria.
#### 3.10.1.1 Application
Pile driving may be considered when footings cannot be founded on granular or stiff cohesive soils within a reasonable depth. At locations where soil conditions would normally permit the use of spread footings but the potential for scour exists, piles may be driven as a protection against scour. Piles may also be driven where an unacceptable amount of settlement of spread footings may occur.
#### 3.10.1.2 Materials
Driven piles may be cast-in-place concrete, pre-cast concrete, pre-stressed concrete, timber, structural steel sections, steel pipe, or a combination of materials.
#### 3.10.1.3 Penetration
Pile penetration shall be determined based on vertical and lateral load capacities of both the pile and subsurface materials. In general, the design penetration for any pile shall be not less than 3D into a hard cohesive or a dense granular material, and not less than 6D into a soft cohesive or loose a granular material.
#### 3.10.1.4 Estimated pile length
Estimated pile lengths of driven piles shall be shown on the drawing and shall be based upon careful evaluation of available subsurface information, axial and lateral capacity calculations, and/or past experience. The maximum length/diameter ratio should not exceed 50 for a single segmental pile.
#### 3.10.1.5 Types of driven piles
Driven piles shall be classified as "friction" or "end bearing" or a combination of both according to the manner in which load transfer is developed. The ultimate load capacity of a pile consists of two parts. One part is due to friction called skin friction or shaft friction or side shear, and the other is due to end bearing at the base or tip of the pile. If the skin friction is greater than about 80% of the end bearing load capacity, the pile is deemed a friction pile and, if the reverse, an end bearing pile. If the end bearing is neglected, the pile is called a “floating pile”.
#### 3.10.1.6 Batter piles
When the lateral resistance of the soil surrounding the piles is inadequate to counteract the horizontal forces transmitted to the foundation, or when increased rigidity of the entire structure is required, batter piles should be used in the foundation. Where negative skin friction loads are expected, batter piles should be avoided, and an alternate method of providing lateral restraint should be used.
Free standing batter piles are subject to bending moments due to their own weight, or external forces from other sources. Batter piles in loose fill or consolidating deposits may become laterally loaded due to settlement of the surrounding soil. In consolidating clay, special precautions, like provision of permanent casing, shall be taken.
#### 3.10.1.7 Selection of soil and rock properties
Soil and rock properties defining the strength and compressibility characteristics of the foundation materials, are required for driven pile design.
#### 3.10.1.8 Pile driving equipment
The pile driving process needs to fulfil assumptions and goals of the design engineer just as much as the design process has to foresee the conception and installation of the pile at the site. This is only possible through the selection of the right driving equipment especially hammer with proper assembly mounted on the most suitable leader, operated according to the specified practices of installation that consists of a series of principle and subsidiary procedures.
There are three principal methods of installing precast displacement piles: jacking, vibratory driving and driving. Jacking is comparatively new method and vibratory driving is suitable to limited soil and pile types (e.g. loose saturated sand, sheet piles). The most common method of installing displacement piles is by driving the piles into the ground by blows of an impact hammer. Because of this, piles installed in this manner are referred to as driven piles. An efficient method of installation requires proper use of the equipment for driving.
The pile driving equipment mainly consists of the components like pile hammer, pile driving leader and driving system components like anvil, cap block, driving head, follower, pile cushion etc. The key to efficient pile driving is a good match of the pile with the hammer and the other system components. Mismatches, often result either inability to drive the pile as specified or in pile damage. A brief account of pile driving equipment especially related to driving by impact hammers is provided in Appendix-F.
#### 3.10.1.9 Design capacity of driven precast pile
The design pile capacity is the maximum load that the driven pile shall support with tolerable movement. In determining the design pile capacity the following items shall be considered:
* (i) Ultimate geotechnical capacity (axial and lateral).
* (ii) Structural capacity of pile section (axial and lateral).
* (iii) The allowable axial load on a pile shall be the least value of the above two capacities.
In determining the design axial capacity, consideration shall be given to the following:
* (i) The influence of fluctuations in the elevation of ground water table on capacity.
* (ii) The effects of driving piles on adjacent structure and slopes.
* (iii) The effects of negative skin friction or down loads from consolidating soil and the effects of lift loads from expansive or swelling soils.
* (iv) The influence of construction techniques such as augering or jetting on pile capacity.
* (v) The difference between the supporting capacity single pile and that of a group of piles.
* (vi) The capacity of an underlying strata to support load of the pile group.
* (vii) The possibility of scour and its effect on axial lateral capacity.
#### 3.10.1.10 Ultimate Geotechnical Capacity of Driven Precast Pile for Axial Load
The ultimate load capacity, $Q_{ult}$, of a pile consists of two parts. One part is due to friction called skin friction or shaft friction or side shear, $Q_s$ and the other is due to end bearing at the base or tip of the pile, $Q_p$.The ultimate axial capacity ($Q_{ult}$) of driven piles shall be determined in accordance with the following for compression loading.
For uplift loading;
The allowable or working axial load shall be determined as:
Where, I is the weight of the pile and \&C is a gross factor of safety as suggested in Tables 6.3.10a and 6.3.10b. Often, for compression loading, the weight term is neglected if the weight, I, is considered in estimating imposed loading. The ultimate bearing capacity (skin friction and/or end bearing) of a single vertical pile may be determined by any of the following methods.
* (i) By the use of static bearing capacity equations
* (ii) By the use of SPT and CPT
* (iii) By load tests
* (iv) By dynamic methods
#### 3.10.1.11 Static bearing capacity equations for driven precast pile capacity
The skin friction, $Q_s$ and end bearing $Q_p$ can be calculated as:
Where, = skin friction area (perimeter area) of the pile=Perimeter × Length
* B = skin frictional resistance on unit surface area of pile that depends on soil properties and loading conditions (drained or undrained)
* $B$ = Width of footing = end bearing area of the pile = Cross-sectional area of pile tip (bottom)
* B4 = end bearing resistance on unit tip area of pile, that depends on soil properties to a depth of 2B (B is the diameter for a circular pile section or length of sides for a square pile section) from the pile tip and loading conditions (drained or undrained)
For a layered soil system containing n number of layers, end bearing resistance can be calculated considering soil properties of the layer at which the pile rests, and the skin friction resistance considers all the penetrating layers calculated as:
Where, ∆K represents the thickness of any "*ℎ* layer and (;PY5P±PY) is the perimeter of the pile in that layer. The manner in which skin friction is transferred to the adjacent soil depends on the soil type. In fine-grained soils, the load transfer is nonlinear and decreases with depth. As a result, elastic compression of the pile is not uniform; more compression occurs on the top part than on the bottom part of the pile. For coarse-grained soils, the load transfer is approximately linear with depth (higher loads at the top and lower at the bottom).
In order to mobilize skin friction and end bearing, some movement of the pile is necessary. Field tests revealed that to mobilize the full skin friction a vertical displacement of 5 to 10 mm is required. The actual vertical displacement depends on the strength of soil and is independent of the pile length and diameter. The full end bearing resistance is mobilized in driven piles when the vertical displacement is about 10% of the pile tip diameter. For bored piles or drilled shafts, a vertical displacement of about 30% of the pile tip diameter is required. The full end bearing resistance is mobilized when slip or failure zones similar to shallow foundations are formed. The end bearing resistance can then be calculated by analogy with shallow foundations. The important bearing capacity factor is :>.
The full skin friction and full end bearing are not mobilized at the same displacement. The skin friction is mobilized at about one-tenth of the displacement required to mobilize the end bearing resistance. This is important in deciding on the factor of safety to be applied to the ultimate load. Depending on the tolerable settlement, different factors of safety can be applied to skin friction and to end bearing.
Generally, piles driven into loose, coarse-grained soils tend to density the adjacent soil. When piles are driven into dense, coarse-grained soils, the soil adjacent to the pile becomes loose. Pile driving usually remolds fine-grained soils near the pile shaft. The implication of pile installation is that the intact shear strength of the soil is changed and one must account for this change in estimations of the load capacity.
#### 3.10.1.12 Axial capacity of driven precast pile in cohesive soil using static bearing capacity equations
The ultimate axial capacity of driven piles in cohesive may be calculated from static formula, given by Equations 6.3.14a, 6.3.14b and 6.3.15, using a total stress method for undrained loading conditions, or an effective stress method for drained loading conditions. Appropriate values of adhesion factor (α) and coefficient of horizontal soil stress (m) for cohesive soils that are consistent with soil condition and pile installation procedure may be used. There are basically two approaches for calculating skin friction:
* (i) The *α* -method that is based on total stress analysis and is normally used to estimate the short term load capacity of piles embedded in fine grained soils. In this method, a coefficient α is used to relate the undrained shear strength OD or ZD to the adhesive stress (B) along the pile shaft. As such,
The end bearing in such a case is found by analogy with shallow foundations and is expressed as:
:+ is a bearing capacity factor and for deep foundation the value is usually 9. OD is the undrained shear strength of soil at the base of the pile. The suffix ‘b’s are indicatives of base of pile. The general equation for :+ is, however, as follows.
4 represents the diameter of the pile at base and *L* is the total length of pile. The skin friction value, B4 5 (OD)4(:+)4 should not exceed 4.0 MPa.
* (ii) The c -method is based on an effective stress analysis and is used to determine both the short term and long term pile load capacities. The friction along the pile shaft is found using Coulomb’s friction law, where the friction stress is given by B 5 CD*′* 5 D*′* ±L\*k*′* . The lateral effective stress, D*′* is proportional to vertical effective stress, $\sigma_v'$ by a co-efficient, K. As such,
Where,
k*′* is the effective angle of internal friction of soil and OCR is the overconsolidation ratio. For normally consolidated clay, c varies from 0.25 to 0.29. The value of c decreases for a very long pile, as such a correction factor is used.
The end bearing capacity is calculated by analogy with the bearing capacity of shallow footings and is determined from:
Where, :> is a bearing capacity factor that depends on angle of internal friction k*′* of the soil at the base of the pile, as presented in Figure 6.3.2. Subscript “b” designates the parameters at the base soil.
![Bearing capacity factor Nq for deep foundation versus angle of internal friction phi]()
#### 3.10.1.13 Axial Capacity of driven precast pile in cohesive soil using SPT values
Standard Penetration Test N-value is a measure of consistency of clay soil and indirectly the measure of cohesion. The skin friction of pile can thus be estimated from N-value. The following relation may be used for preliminary design of ultimate capacity of concrete piles in clay soil.
For skin friction the relationship is as under.
For end bearing, the relationship is as under.
Where, :\_ º= is the average N-value over the pile shaft length and :º= is the N-value in the vicinity of pile tip. A factor of safety of 3.5 shall be used to estimate allowable capacity.
#### 3.10.1.14 Axial capacity of driven precast pile in cohesionless soil using static bearing capacity equations
Piles in cohesionless soils shall be designed by effective stress methods of analysis for drained loading conditions. The ultimate axial capacity of piles in cohesionless soils may also be calculated using empirical effective stress method or from in-situ methods and analysis such as the cone penetration or pressure meter tests. Dynamic formula may be used for driven piles in cohesionless soils such as gravels, coarse sand and deposits where pore pressure developed due to driving is quickly dissipated. For piles in cohesionless soil, the ultimate side resistance may be estimated using the following formula:
Where, $\sigma_v'$ is the effective vertical stress at the level under consideration. The values for β are as under.
For uncemented calcareous sand the value of c varies from 0.05 to 0.10.
The following equation, as used for cohesive soil, may be used to compute the ultimate end bearing capacity of piles in sandy soil in which, the maximum effective stress, $\sigma_v'$ allowed for the computation is 240 kPa. Figure 6.3.2 may also be used to estimate the value of :>.
#### 3.10.1.15 Critical depth for end bearing and skin friction
The vertical effective stress ($\sigma_v'$ or $\sigma_v'$ ) increases with depth. Hence the skin friction should increase with depth indefinitely. In reality skin friction does not increase indefinitely. It is believed that skin friction would become a constant at a certain depth. This depth is named critical depth. Pile end bearing in sandy soils is also related to effective stress. Experimental data indicates that end bearing capacity does not also increase with depth indefinitely. Due to lack of a valid theory, Engineers use the same critical depth concept adopted for skin friction for end bearing capacity as well. Both the skin friction and the end bearing capacity are assumed to increase till the critical depth, #+ and then maintain a constant value. Following approximations may be used for the critical depth in relation to diameter of pile, D.
5 10# for loose sand #+ 5 15# for medium dense sand #+ 5 20# for dense sand
#### 3.10.1.16 Axial Capacity of Driven Precast Pile in Cohesionless Soil using SPT Values
Standard Penetration Test N-value is a measure of relative density hence angle of internal friction of cohesionless soil. The skin friction of pile can thus be estimated from N-value. The following relation may be used for ultimate capacity of concrete piles in cohesionless soil and non-plastic silt.
For skin friction the relationship is as under.
For sand:
For non-plastic silt:
For end bearing, the relationship is as under.
For sand:
For non-plastic silt:
Where, :\_ º= is the average N-value over the pile shaft length and :º= is the N-value in the vicinity of pile tip. A higher factor of safety of 3.5 should be used to estimate allowable capacity.
#### 3.10.1.17 Axial capacity of driven precast pile using pile load Test
Generally, the load on test pile to determine ultimate capacity is twice the design load. The test load on service/working pile is 1.5 times the design load. The following criteria should be met in deciding the allowable/safe pile capacity.
**Safe Load for Single Pile**
* (a) Two thirds of the final load at which the load displacement attains a value of 12 mm unless otherwise required in a given case on the basis of nature and type of structure in which case, the safe load should be corresponding to the stated total displacement permissible.
* (b) Fifty (50) percent of the final load at which the total displacement equals to 10 percent of pile diameter case of uniform diameter piles and 7.5 percent of bulb diameter in case of under-reamed piles.
**Safe Load for Pile Group**
* (a) Final load at which the load displacement attains a value of 25 mm unless otherwise required in a given case on the basis of nature and type of structure, and
* (b) Two thirds of the final load at which the total displacement attains a value of 40 mm.
#### 3.10.1.18 Selection of factor of safety for driven precast pile
Driven pile in soil shall be designed for a minimum overall factor of safety of 2.0 against bearing capacity failure (end bearing, side resistance or combined) when the design is based on the results of a load test conducted at the site, with good quality control. Otherwise, it shall be designed for a minimum factor of safety 3.0. The minimum recommended overall factor of safety is based on an assumed normal level of field quality control during construction. If a normal level of field quality control cannot be assured, higher minimum factors of safety shall be used. The recommended values of overall factor of safety on ultimate axial load capacity based on specified construction control is given in Tables 6.3.10a and 6.3.10b.
Partial factor of safety may be used independently for skin friction and end bearing. The values of partial factor of safety may be taken as 1.5 and 3.0 respectively for skin friction and end bearing. The design/allowable load may be taken as the minimum of the values considering overall and partial factor of safety.
**Table 6.3.10a: Factor of Safety for Deep Foundation for Downward and Upward Load**
| **Structure** | **Design** | **Probability** | **D** | **esign Fact** | **or of Safe** | **ty** |
| ----------------------------------------------------------------------------------- | --------------- | --------------- | ------------------------- | --------------------------- | ------------------------- | ---------------------------- |
| | **Life (yrs.)** | **of Failure** | | | | |
| | | | **Good**
**Control** | **Normal**
**Control** | **Poor**
**Control** | **V. Poor**
**Control** |
| Monument | > 100 | 10-5 | 2.30 | 3.00 | 3.50 | 4.00 |
| Permanent | 25 -100 | 10-4 | 2.00 | 2.50 | 2.80 | 3.00 |
| Temporary | \< 25 | 10-3 | 1.40 | 2.00 | 2.30 | 2.80 |
| **Table 6.3.10b: Guidelines for Investigation, Analysis and Construction Control** | | | | | | |
| **Item** | **Good**
**Control** | **Normal**
**Control** | **Poor**
**Control** | **V. Poor**
**Control** |
| ---------------------------------------- | ------------------------- | --------------------------- | ------------------------- | ---------------------------- |
| Proper Subsoil Investigation | Yes | Yes | Yes | Yes |
| Proper Review of Subsoil
Report | Yes | Yes | Yes | Yes |
| Supervision by Competent | | | | |
| Geotechnical/Foundation | Yes | Yes | Yes | No |
| Engineer | | | | |
| Load Test Data | Yes | Yes | Yes | No |
| Qualification of Contractor | Yes | Yes | No | No |
| Proper Construction
Equipment’s | Yes | No | No | No |
| Maintaining Proper
Construction Log | Yes | No | No | No |
#### 3.10.1.19 Group piles and group capacity of driven precast piles
All piles shall be braced to provide lateral stability in all directions. Three or more piles connected by a rigid cap shall be considered as being braced (stable), provided that the piles are located in a radial direction from the centroid of the group, not less than 60o apart circumferentially. A two pile group in a rigid cap shall be considered to be braced along the axis connecting the two piles. Piles supporting walls shall be driven alternately in lines at least 300 mm apart and located symmetrically under the centre of gravity of the wall load, unless effective measures are taken to cater for eccentricity and lateral forces, or the wall piles are adequately braced to provide lateral stability. Individual piles are considered stable if the pile tops are laterally braced in two directions by construction, such as a structural floor slab, grade beams, struts, or walls.
Group pile capacity of driven piles should be determined as the product of the group efficiency, number of piles in the group and the capacity of a single pile. In general, a group efficiency value of 1.0 should be used except for friction piles driven in cohesive soils. The minimum center-to-center pile spacing of 2.5B is recommended. The nominal dimensions and length of all the piles in a group should be similar.
#### 3.10.1.20 Pile caps
Pile caps shall be of reinforced concrete. The soil immediately below the pile cap shall not be considered as carrying any vertical load. The tops of all piles shall be embedded not less than 75 mm into pile caps and the cap shall extend at least 100 mm beyond the edge of all piles. The tops of all piles shall be cut back to sound material before capping. The pile cap shall be rigid enough, so that the imposed load can be distributed on the piles in a group equitably. The cap shall generally be cast over a 75 mm thick levelling course of concrete. The clear cover for the main reinforcement in the cap slab under such condition shall not be less than 50 mm.
#### 3.10.1.21 Lateral load capacity on driven precast piles
Lateral capacity of vertical single piles shall be the least of the values calculated on the basis of soil failure, structural capacity of the pile and deflection of the pile head. In the analysis, pile head conditions (fixed-head or free-head) should be considered. For estimating the depth of fixity, established method of analysis shall be used. The main reinforcement of pile foundation is usually governed by the lateral load capacity and vice versa. Deflection calculations require horizontal subgrade modulus of the surrounding soil. When considering lateral load on piles, the effect of other coexistent loads, including axial load on the pile, shall be taken into consideration for checking structural capacity of the shaft.
To determine lateral load capacity, lateral load tests shall be performed with at least two times the proposed design working load. Allowable lateral load capacity will be the least from the following criteria.
* (i) Half of the lateral load at which lateral movement of the pile head is 12 mm or lateral load corresponding to any other specified displacement as per performance requirements.
* (ii) Final load at which the total displacement corresponds to 5 mm or lateral load corresponding to any other specified displacement as per performance requirements.
All piles standing unbraced in air, water or soils not capable of providing lateral support shall be designed as columns in accordance with the provisions of this Code.
#### 3.10.1.22 Vertical ground movement and negative skin friction in driven precast piles
The potential for external loading on a pile by vertical ground movements shall be considered as part of the design. Vertical ground movements may result in negative skin friction or downdrag loads due to settlement of compressible soils or may result in uplift loads due to heave of expansive soils. For design purposes, the full magnitude of maximum vertical ground movement shall be assumed.
Driven piles installed in compressible fill or soft soil subject to compression shall be designed against downward load due to downdrag. The potential for external loading on a pile by negative skin friction/downdrag due to settlement of compressible soil shall be considered as a part of the design load. Evaluation of negative skin friction
shall include a load-transfer method of analysis to determine the neutral point (i.e., point of zero relative displacement) and load distribution along shaft. Due to the possible time dependence associated with vertical ground movement, the analysis shall consider the effect of time on load transfer between the ground and shaft and the analysis shall be performed for the time period relating to the maximum axial load transfer to the pile. Negative skin friction loads may be reduced by application of bitumen or other viscous coatings to the pile surfaces. In estimating negative skin friction the following factors shall be considered :
* (i) Relative movement between soil and pile shaft.
* (ii) Relative movement between any underlying compressible soil and pile shaft.
* (iii) Elastic compression of the pile under the working load.
* (iv) The rate of consolidation of the compressible layer.
* (v) Negative skin friction is mobilized only when tendency for relative movement between pile shaft and surrounding soil exists.
#### 3.10.1.23 Driven precast pile in expansive soils (upward movement)
Piles driven in swelling soils may be subjected to uplift forces in the zone of seasonal moisture change. Piles shall extend a sufficient distance into moisture-stable soils to provide adequate resistance to swelling uplift forces. In addition, sufficient clearance shall be provided between the ground surface and the underside of pile caps or grade beams to preclude the application of uplift loads at the pile cap. Uplift loads may be reduced by application of bitumen or other viscous coatings to the pile surface in the swelling zone.
#### 3.10.1.24 Dynamic/Seismic Design of Driven Precast Pile
In case of submerged loose sands, vibration caused by earthquake may cause liquefaction or excessive total and differential settlements. This aspect of the problem shall be investigated and appropriate methods of improvements should be adopted to achieve suitable values of N *.* Alternatively, large diameter drilled pier foundation shall be provided and taken to depths well into the layers which are not likely to liquefy.
#### 3.10.1.25 Protection against corrosion and abrasion in driven precast pile
Where conditions of exposure warrant a concrete encasement or other corrosion protections shall be used on steel piles and steel shells. Exposed steel piles or steel shells shall not he used in salt or brackish water, and only with caution in fresh water. Details are given in Sec 3.6.2.
#### 3.10.1.26 Dynamic monitoring of driven precast pile
Dynamic monitoring may be specified for piles installed in difficult subsurface conditions such as soils with obstructions and boulders to evaluate compliance with structural pile capacity. Dynamic monitoring may also be considered for geotechnical capacity verification, where the size of the project or other limitations deters static load testing.
#### 3.10.1.27 Maximum allowable driving stresses in driven precast pile
Maximum allowable driving stresses in pile material for top driven piles shall not exceed 0.9BH (compression), 0.9BH (tension) for steel piles, 0.85B+*′* concrete (compression) and 0.7BH steel reinforcement (tension) for concrete piles and 0.85B+*′* −B!+ (compression) for prestressed concrete piles.
#### 3.10.1.28 Effect of buoyancy in driven precast pile
The effects of hydrostatic pressure shall be considered in the design of driven piles, where used with foundation subjected to buoyancy forces.
#### 3.10.1.29 Protection against Deterioration of Driven Precast Piles
* (a) Steel Pile
A steel pile design shall consider that steel piles may be subject to corrosion, particularly in fill soils (low pH soils, acidic, pH value \<5.5) and marine environments. In fact, extremely acid soils (below pH 4.5) and very strongly alkaline soils (above pH 9.1) have significantly high corrosion loss rates when compared to other soils. For structural elements, the Code considers a site to be corrosive if one or more of the following conditions exist for the representative soil and/or water samples taken at the site: Chloride concentration is 500 ppm or greater, sulfate concentration is 2000 ppm or greater, or the pH is less than 6. A field electric resistivity survey or resistivity testing and pH testing of soil and ground water samples should be used to evaluate the corrosion potential.
Methods of protecting steel piling in corrosive environments include use of protective coatings, cathodic protection, and increased steel area. The corrosion guidelines are provided in Tables 6.3.6a and 6.3.6b.
(Concrete Pile)
A concrete pile foundation design shall consider that deterioration of concrete piles can occur due to sulfates in soil, ground water, or sea water; chlorides in soils and chemical wastes; acidic ground water an organic acids. Laboratory testing of soil and ground water samples for sulfates and pH is usually sufficient to assess pile deterioration potential. A full chemical analysis of soil and water samples is recommended when chemical wastes are suspected. Methods of protecting concrete piling include dense impermeable concrete, sulfate resisting Portland cement, minimum cover requirements for reinforcement and use of epoxies, resins, or other protective coatings.
(Timber Pile)
A timber pile foundation (used for temporary structures) design shall consider that deterioration of timber piles can occur due to decay from wetting and drying cycles or from insects or marine borers Methods of protecting timber piling include pressure treating with creosote or other wood preservers.
#### 3.10.1.30 Pile spacing, clearance and embedment in driven precast pile
End bearing driven piles shall be proportioned such that the minimum center-tocenter pile spacing shall exceed the greater of 750 mm or 2.5 pile diameters/widths. The distance from the side of any pile to the nearest edge of the pile cap shall not be less than 100 mm. The spacing of piles shall be that the average load on the supporting strata will not exceed the safe bearing value of those strata as determined by test boring or other established methods.
Piles deriving their capacity from frictional resistance shall be sufficiently apart to ensure that the zones of soil from which the piles derive their support do not overlap to such an extent that their bearing values are reduced. Generally, in such cases, the spacing shall not be less than 3.0 times the diameter of the shaft. The tops of piles shall project not less than 75 mm into concrete after all damaged pile material has been removed.
#### 3.10.1.31 Structural capacity of driven precast pile section
The cross-section of driven piles shall be of sufficient size and pile material shall have the necessary structural strength to resist all handling stresses during driving or installation and the necessary strength to transmit the load imposed on them to the underlying and surrounding soil. Pile diameter/cross-section of a pile shaft at any level shall not be less than the designated nominal diameter/cross-section. The structural design of piles must consider each of the following loading conditions.
* (i) Handling loads are those imposed on the pile between the time it is fabricated and the time it is in the pile driver leads and ready to be driven. They are generated by cranes, forklifts, and other construction equipment.
* (ii) Driving loads are produced by the pile hammer during driving.
* (iii) Service loads are the design loads from the completed structures.
The maximum allowable stress on a pile shall not exceed 0.33B+*′* for precast concrete piles and 33B+*′* −B!+ for prestressed concrete piles and 0.25BH for steel H-piles. The axial carrying capacity of a pile fully embedded in soil with undrained shear strength greater than 10 kN/m2 shall not be limited by its strength as long column. For driven piles in weaker soils (undrained shear strength less than 10 kN/m2 ), due consideration shall be given to determine whether the shaft behaves as a long column or not. If necessary, suitable reductions shall be made in its structural strength considering buckling. The effective length of a pile not secured against buckling by adequate bracing shall be governed by fixity conditions imposed on it by the structure it supports and by the nature of the soil in which it is installed.
**Minimum Reinforcement in Driven Concrete Pile**
The longitudinal and transverse steel provided in piles should enable the pile to :
* Withstand handling stresses
* Endure driving stresses
* Provide the necessary structural capacity
The maximum bending stress is produced while handling if the pile is pitched at the head. To prevent whipping during handling, length/diameter ratio of the pile should never exceed 50. Otherwise, segmental pile should be used. Considering all of these, the recommended area of main reinforcement for precast concrete piles, designed
mainly for vertical load with small lateral capacity, should not be less than the following percentages of the cross sectional area of the piles. In all cases, its adequacy for handling stresses shall be checked. The following reinforcement provisions may not be valid for laterally loaded piles or piles for uplift resistance.
* (i) Pile length \< 30 times the least width : 1.00%
* (ii) Pile length 30 to 40 times the least width : 1.5%
* (iii) Pile length > 40 times the least width : 2%
The lateral reinforcement resists the driving stresses induced in the piles and should be in the form hoops or links of diameter not less than 6 mm. The volume of lateral reinforcement shall not be less than the following :
* (i) At each end of the pile for a distance of about three times the least width/diameter – not less than 0.4% of the gross volume of the pile.
* (ii) In the body of the pile – not less than 0.2% of the gross volume of the pile.
* (iii) The transition between closer spacing and the maximum should be gradual over a length of 3 times the least width/diameter.
**Minimum Grades of Concrete**
The minimum 28 days cylinder strength of concrete for driven piles is 21 MPa. Depending on driving stresses, the following grades of concrete should be used.
* (i) For hard driving (driving stress > 1000 kN/m2 ) – 28 MPa
* (ii) For easy driving (driving stress ≤ 1000 kN/m2 ) – 21 MPa
### **3.10.2 Driven Cast-in-Place Concrete Piles**
Driven cast-in-place concrete piles shall be in general cast in metal shells driven into the soil that will remain permanently in place. However, other types of cast-in-place piles, plain or reinforced, cased or uncased, may be used if the soil conditions permit their use and if their design and method of placing are satisfactory.
#### 3.10.2.1 Shape
Cast-in-place concrete piles may have a uniform cross-section or may be tapered over any portion.
#### 3.10.2.2 Minimum area
The minimum area at the butt of the pile shall be 650 cm2 and the minimum diameter at the tip of the pile shall be 200 mm.
#### 3.10.2.3 General reinforcement requirements
Depending on the driving and installation conditions and the loading condition, the amount of reinforcement and its arrangement shall vary. Cast-in-place piles, carrying axial loads only, where the possibility of lateral forces being applied to the piles is insignificant, need not be reinforced where the soil provides adequate lateral support. Those portions of cast-in-place concrete piles that are not supported laterally shall be designed as reinforced concrete columns and the reinforcing steel shall extend 3000 mm below the plane where the soil provides adequate lateral restraint. Where the shell is smooth pipe and more than 3 mm in thickness, it may be considered as load carrying in the absence of corrosion. Where the shell is corrugated and is at least 2 mm in thickness, it may be considered as providing confinement in the absence of corrosion.
#### 3.10.2.4 Reinforcement in superstructure
Sufficient reinforcement shall be provided at the junction of the pile with the superstructure to make a suitable connection. The embedment of the reinforcement into the cap shall be as specified for precast piles.
#### 3.10.2.5 Shell requirements
The shell shall be of sufficient thickness and strength, so as to hold its original form and show no harmful distortion after it and adjacent shells had driven and the driving core, if any, has been withdrawn. The plans shall stipulate that alternative designs of the shell must be approved by the Engineer before driving is done.
#### 3.10.2.6 Splices
Piles may be spliced provided the splice develops the full strength of the pile. Splices should be detailed on the contract plans. Any alternative method of splicing providing equal results may be considered for approval.
#### 3.10.2.7 Reinforcement cover
The reinforcement shall be placed a clear distance of not less than 50 mm from the cased or uncased sides. When piles are in corrosive or marine environments, or when concrete is placed by the water or slurry displacement methods, the clear distance shall not be less than 75 mm for uncased piles and piles with shells not sufficiently corrosion resistant. Reinforcements shall extend to within 100 mm of the edge of the pile cap.
#### 3.10.2.8 Installation
Steel cased piles shall have the steel shell mandrel driven their full length in contact with surrounding soil, left permanently in place and filled with concrete. No pile shall be driven within 4.5 times the average pile diameter of a pile filled with concrete less than 24 hours old. Concrete shall not be placed in steel shells within the heave range of driving.
#### 3.10.2.9 Concreting
For bored or driven cast-in-situ piles, concrete shall be deposited in such a way as to preclude segregation. Concrete shall be deposited continuously until it is brought to the required level. The top surface shall be maintained as level as possible and the formation of seams shall be avoided.
For under-reamed piles, the slump of concrete shall range between 100 mm and 150 mm for concreting in water free holes. For large diameter holes concrete may be placed by tremie or by drop bottom bucket; for small diameter boreholes a tremie shall be utilized.
A slump of 125 mm to 200 mm shall be maintained for concreting by tremie. In case of tremie concreting for piles of smaller diameter and length up to 10 m, the minimum cement content shall be 350 kg/m3 of concrete. For larger diameter and/or deeper piles, the minimum cement content shall be 400 kg/m3 of concrete.
For concreting under water, the concrete shall contain at least 10 percent more cement than that required for the same mix placed in the dry. The amount of coarse aggregate shall be not less than one and a half times, nor more than two times, that of the fine aggregate. The materials shall be so proportioned as to produce a concrete having a slump of not less than 125 mm, nor more than 200 mm.
#### 3.10.2.10 Structural integrity
Bored piles shall be installed in such a manner and sequence as to prevent distortion or damage to piles being installed or already in place, to the extent that such distortion or damage affects the structural integrity of pile.
### **3.10.3 Prestressed Concrete Piles**
#### 3.10.3.1 Shape and size
Prestressed concrete piles that are generally octagonal, square or circular shall be of approved size and shape. Concrete in prestressed piles shall have a minimum compressive strength (cylinder), B+*′* of 35 MPa at 28 days. Prestressed concrete piles may be solid or hollow. For hollow piles, precautionary measures should be taken to prevent breakage due to internal water pressure during driving.
#### 3.10.3.2 Reinforcement
Within the context of this Code, longitudinal prestressing is not considered as loadbearing reinforcement. Sufficient prestressing steel in the form of high-tensile wire, strand, or bar should be used so that the effective prestress after losses is sufficient to resist the handling, driving, and service-load stresses. Post-tensioned piles are cast with sufficient mild steel reinforcement to resist handling stresses before stressing. For pretensioned piles, the longitudinal prestressing steel should be enclosed in a steel spiral with the minimum wire size ranging from ACI 318 W3.5 (nominal area 0.035 in2 , nominal dia=0.211 inch) to W5 (nominal area 0.05 in2 , nominal dia=0.252 inch) depending on the pile size. The wire spiral should have a maximum 6 in. (150 mm) pitch with closer spacing at each end of the pile and several close turns at the tip and pile head. The close spacing should extend over at least twice the diameter or thickness of the pile, and the few turns near the ends are often at 1 in. (25 mm) spacing. Occasionally, prestressed piles are designed and constructed with conventional reinforcement in addition to the prestressing steel to increase the structural capacity and ductility of the pile. This reinforcement reduces the stresses in the concrete and should be taken into account.
For prestressed concrete piles, the effective prestress after all losses should not be less than 700 lb/in2 (4.8 MPa). Significantly higher effective prestress values are commonly used and may be necessary to control driving stresses in some situations. Bending stresses shall be investigated for all conditions of handling, taking into account the weight of the pile plus 50 percent allowance for impact, with tensile stresses limited to $5\sqrt{f_c'}$.
#### 3.10.3.3 Vertical and spiral reinforcement
The full length of vertical reinforcement shall be enclosed within spiral reinforcement. For piles up to 600 mm in diameter, spiral wire shall be No.5 (U.S. Steel Wire Gage). Spiral reinforcement at the ends of these piles shall have a pitch of 75 mm for approximately 16 turns.
In addition, the top 150 mm of pile shall have five turns of spiral winding at 25 mm pitch. For the remainder of the pile, the vertical steel shall be enclosed with spiral reinforcement with not more than 150 mm pitch. For piles having diameters greater than 600 mm. spiral wire shall be No.4 (U.S. Steel Wire Gauge). Spiral reinforcement at the end of these piles shall have a pitch of 50 mm for approximately 16 turns. In addition, the top 150 mm of pile shall have four turns of spiral winding at 38 mm pitch. For the remainder of the pile, the vertical steel shall be enclosed with spiral reinforcement with not more than 100 mm pitch. The reinforcement shall be placed at a clear distance from the face of the prestressed pile of not less than 50 mm.
#### 3.10.3.4 Driving and handling stresses
A prestressed pile shall not be driven before the concrete has attained a compressive strength of at least 28 MPa, but not less than such strength sufficient to withstand handling and driving forces.
### **3.10.4 Bored Piles**
In bored cast in place piles, the holes are first bored with a permanent or temporary casing or by using bentonite slurry to stabilize the sides of the bore. A prefabricated steel cage is then lowered into the hole and concreting is carried by tremie method.
#### 3.10.4.1 Shape and size
Bored cast-in-situ concrete piles that are generally circular in section shall be of approved size and shape. Concrete in bored cast-in-situ concrete piles shall have a minimum compressive strength (cylinder), B+*′* of 21 MPa at 28 days.
#### 3.10.4.2 Dimension
All shafts should be sized in 50 mm increments with a minimum shaft diameter of 400 mm.
#### 3.10.4.3 Ultimate geotechnical capacity of bored pile for axial load
The basic concept of ultimate bearing capacity and useful equations for axial load capacity are identical to that of driven pile as described in Art. 3.10.1.10.
#### 3.10.4.4 Axial capacity of bored piles in cohesive soil using static bearing capacity equations
The ultimate axial capacity of bored piles in cohesive may be calculated from the same static formula as used for driven piles, given by Equations 6.3.14a, 6.3.14b and 6.3.15, using a total stress method for undrained loading conditions, or an effective stress method for drained loading conditions. The skin friction B may be taken as 2/3rd the value of driven piles and the end bearing B4 may be taken as 1/3rd of that of driven pile.
#### 3.10.4.5 Axial capacity of bored piles in cohesive soil using SPT values
The following relations may be used for preliminary design of ultimate capacity of concrete bored piles in clay soils.
For skin friction the relationship is as under.
For end bearing, the relationship is as under.
Where, :\_ º= is the average N-value over the pile shaft length and :º= is the N-value in the vicinity of pile tip. A higher factor of safety of 3.5 should be used to estimate allowable capacity.
#### 3.10.4.6 Axial capacity of bored piles in cohesionless soil using static bearing
The ultimate axial capacity of bored piles in cohesive soil may be calculated from the same static formula as used for driven piles described in Sec 3.10.1.10. The skin friction B may be taken as 2/3rd the value of driven pile and the end bearing B4 may be taken as 1/3rd of driven pile.
**Critical Depth for End Bearing and Skin Friction**
Similar to driven piles, following approximations may be used for the critical depth in relation to pile diameter, D.
#### 3.10.4.7 Axial capacity of bored piles in cohesionless soil using SPT values
The following relations may be used for preliminary design of ultimate capacity of concrete bored piles in sand and non-plastic silty soils.
For skin friction the relationship is as under :
For sand
For non-plastic silt:
For end bearing, the relationship is as under.
For sand
For non-plastic silt:
Where, *N* 60 is the average N-value over the pile shaft length and *N60* is the N-value in the vicinity of pile tip (down to a depth of 3D). A higher factor of safety of 3.5 should be used to estimate allowable capacity.
#### 3.10.4.8 Axial capacity of bored pile using pile load test
The procedures and principles of pile load test for ultimate capacity are similar to that of driven piles.
#### 3.10.4.9 Structural capacity of bored concrete pile/drilled shaft
**Minimum Reinforcement in Bored Concrete Pile**
For piles loaded in compression alone, it is generally only necessary to reinforce the shaft to a depth of 2 m greater than the depth of temporary casing to prevent any tendency for concrete lifting when pulling the casing. Piles subject to tension or lateral forces and eccentric loading (possibly being out of position or out of plumb) do however require reinforcement suitable to cope with these forces. The following criteria for typical nominal reinforcement for piles in compression shall be considered. Table 6.3.11 may be used as guidelines. The restrictions that apply to the use of this Table have to be carefully considered in any particular application.
**Table 6.3.11: Guidance on the Minimum Reinforcing Steel for Bored Cast-in-place Piles**
| **Pile Diameter**
**(mm)** | **Main Rei** | **nforcement** | **Lateral**
**Reinfor** | **(Hoop)**
**cement** |
| ------------------------------- | -------------------------- | --------------- | ---------------------------- | -------------------------- |
| | **Bar Size**
**(mm)** | **No. of Bars** | **Bar Size (mm)** | **Pitch (mm)** |
| 400 | 16 | 6 | 8 | 200 |
| 450 | 16 | 6 | 8 | 200 |
| 500 | 16 | 8 | 8 | 250 |
| 600 | 16 | 8 | 8 | 250 |
| 750 | 16 | 10 | 10 | 300 |
| 900 | 16 | 10 | 10 | 300 |
| 1050 | 16 | 12 | 10 | 300 |
| 1200 | 16 | 12 | 10 | 300 |
| 1500 | 20 | 12 | 10 | 400 |
| 1800 | 20 | 12 | 10 | 400 |
| 2100 | 20 | 16 | 10 | 400 |
| 2400 | 25 | 16 | 12 | 500 |
| Notes: | | | | |
* (a) Yield strength of steel = 420 MN/m2
* (b) The above guidelines are for “build-ability” only: They are not appropriate Where:
* (i) Piles are required to resist any applied tensile or bending forces- the reinforcement has to be designed for the specific loading conditions.
* (ii) Piles are required to accommodate positional and verticality tolerances, or where they are constructed through very soft alluvial deposits (cu \< 10 kN/m2 ). Specific reinforcement design is then necessary.
* (c) Minimum depth of reinforcement is taken as 3 m below cutoff for simple bearing only. Any lateral loads or moments taken by the pile will require reinforcement to extend to some depth below the zone subjected to bending forces. This zone may be determined from a plot of the bending moment with depth. Furthermore the reinforcement would normally extend at least 1 m below the depth of any temporary casing.
* (d) Even with the appropriate reinforcement care will still be required to prevent damage to piles by construction activities especially during cutting-down or in the presence of site traffic.
The longitudinal reinforcement shall be of high yield steel bars (min BH = 420 Mpa) and shall not be less than:
Where, + is the gross cross-sectional area of the pile. The minimum diameter for the longitudinal bars should not be less than 16 mm for large diameter (diameter ≥ 600 mm) piles. Piles should have at least 6 longitudinal bars.
The assembled reinforcement cage should be sufficiently strong to sustain lifting and lowering into the pile bore without permanent distortion or displacement of bars or in addition bars should not be so densely packed that concrete aggregate cannot pass freely between them. Hoop reinforcement (for shear) is not recommended closer than 100 mm centres. Minimum Concrete cover to the reinforcement periphery shall be 75 mm. This guidance is only applicable for piles with vertical load.
**Minimum Grades of Concrete**
The integrity of pile shaft is of paramount importance, and the concreting mixes and methods that have been evolved for bored piles are directed towards this as opposed to the high strength concrete necessary for precast piles or structural work above ground. This prerequisite has led to the adoption of highly workable mixes, and the “total collapse” mix for tremie piles has been mentioned. In order to ensure that the concrete flows between the reinforcing bars with ease, and into the interstices of the soil, a high slump, self-compacting mix is called for. A minimum cement content of 350 kg/m3 is generally employed under dry placement condition, increasing to 400 kg/m3 under submerged condition at slumps greater than 125 mm, with a corresponding increase in fine aggregate content to maintain the cohesion of the mix. The water cement ratio in all cases is recommended as 0.45. Three mixes as recommended are given in Table 6.3.12.
**Table 6.3.12: Recommended Concrete Slumps for Cast-in-place Bored Piles**
| Mix | Slump (mm) | Conditions of use |
| --- | ---------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| A | 125 | Poured into water-free unlined bore. Widely spaced reinforcement leaving ample room for free movement of the concrete between bars. |
| B | 150 | Where reinforcement is not placed widely enough to give free movement of concrete between bars. Where cutoff level of concrete is within casing. Where pile diameter is \< 600 mm. |
| C | 200 | Where concrete is to be placed by tremie under water or bentonite in slurry. |
#### 3.10.4.10 Selection of factor of safety for bored pile
Selection of factor of safety for axial capacity of bored pile is similar to that used for driven piles.
#### 3.10.4.11 Group capacity of bored pile
The behavior of group bored piles is almost similar to that of driven piles. For the pile cap, lateral load capacity, vertical ground movement, negative skin friction, piles in expansive soil, dynamic and seismic design, corrosion protection, dynamic monitoring and buoyancy. Sec 3.10.1.18 should be consulted as they are similar for both driven and bored piles. However, Individual bored piles are considered stable if the pile tops are laterally braced in two directions by construction, such as a structural floor slab, grade beams, struts, or walls. Generally, the use of a single pile as foundation is not recommended unless the diameter is 600 mm or more.
### **3.10.5 Settlement of Driven and Bored Piles**
The settlement of axially loaded piles and pile groups at the allowable loads shall be estimated. Elastic analysis, load transfer and/or finite element techniques may be used. The settlement of the pile or pile group shall not exceed the tolerable movement limits as recommended for shallow foundations (Table 6.3.7). When a pile is loaded, two things would happen involving settlement.
* The pile would settle into the soil
* The pile material would compress due to load
The settlement of a single pile can be broken down into three distinct parts.
* Settlement due to axial deformation, $S_e$
* Settlement at the pile tip, $S_c$
* Settlement due to skin friction, C
* C"()Ð\<) 5 $S_e$ + $S_c$ + C (6.3.35a)
Moreover, piles acting in a group could undergo long term consolidation settlement.
Settlement due to axial deformation of a single pile can be estimated as :
Where, ?! = Load transferred to the soil at tip level ? = Total skin friction load L = Length of the pile A = Cross section area of the pile %A = Young’s modulus of pile material L = 0.5 for clay and silt soils
Pile tip settlement, $S_c$ can be estimated as :
Where, ?! = Load transferred to the soil at tip level = Diameter of the pile X = Ultimate end bearing capacity ! = Empirical coefficient as given in Table 6.3.13
**Table 6.3.13: Typical Values of** "V **for Settlement Calculation of Single Pile**
| **Soil Type** | **Values** | **of**"V |
| --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------- | -------------- |
| | **Driven Pile** | **Bored Pile** |
| Dense Sand | 0.02 | 0.09 |
| Loose Sand | 0.04 | 0.18 |
| Stiff Clay | 0.02 | 0.03 |
| Soft Clay | 0.03 | 0.06 |
| Dense Silt | 0.03 | 0.09 |
| Loose Silt | 0.05 | 0.12 |
| Skin friction acting along the shaft would stress the surrounding soil. Skin friction acts upward direction along the pile. The force due to pile on surrounding soil would be in downward direction. When the pile is loaded, the pile would slightly move down. The pile would drag the surrounding soil with it. Hence, the pile settlement would occur due to skin friction as given by : | | |
Short Term Pile Group Settlement
Short term or elastic pile group settlement can be estimated using the following relation.
Where,
C = Settlement of the pile group
\= Diameter of the pile
Interestingly, geometry of the group does not have much of an influence on the settlement. As such, Group Settlement Ratio, @ of a pile group consisting of n number of piles can be approximated as follows :
The settlement of the group can be estimated as the highest value as obtained from Equations 6.3.37 and 6.3.38.
**Long Term Settlement for Pile Group**
For pile groups, settlement due to consolidation is more important than for single piles. Consolidation settlement of pile group in clay soil is computed using the following simplified assumptions.
* The pile group is assumed to be a solid foundation with a depth 2/3rd the length of the piles
* Effective stress at mid-point of the clay layer is used to compute settlement
If soil properties are available, the consolidation settlement (S) may be obtained from the following equation. The depth of significant stress increase (10%) or the depth of bed rock whichever is less should be taken for computation of settlement. Stress distribution may be considered as 2 vertical to 1 horizontal.
Where,
* \= Compression index of soil
P = initial void ratio
* \= Thickness of the clay layer
σ *′* = Initial effective stress at mid-point of the clay layer σ *′* != Increase in effective stress at mid-point of the clay layer due to pile load.
In absence of soil properties the following empirical equations may be used to estimate the long term consolidation settlement of clay soils.
For clay:
For sand:
Where,
* \= Thickness of the clay layer
* σ*′* = Initial effective stress at mid-point of the clay layer
* σ1 *′* = New effective stress at mid-point of the clay layer after pile load.
* σ7*′* = Reference stress (100 kPa)
* 9 = Dimensionless modulus number as obtained from Table 6.3.14
* d = Stress exponent as obtained from Table 6.3.14.
**Table 6.3.14: Settlement Parameters**
| **Soil** | **Density** | **Modulus**
**Number, M** | **Stress**
**Exponent, j** |
| ------------ | ----------------- | ------------------------------ | ------------------------------- |
| Till | V. Dense to Dense | 1000 - 300 | 1.0 |
| Gravel | - | 400 - $B$ = Width of footing0 | 0.5 |
| Sand | Dense | 400 - 250 | 0.5 |
| Sand | Medium Dense | 250 - 150 | 0.5 |
| Sand | Loose | 150 - 100 | 0.5 |
| Silt | Dense | 200 - 80 | 0.5 |
| Silt | Medium Dense | 80 - 60 | 0.5 |
| Silt | Loose | 60 - $B$ = Width of footing0 | 0.5 |
| Silty Clay | Stiff | 60 - $B$ = Width of footing0 | 0.5 |
| Silty Clay | Medium Stiff | 20 - 10 | 0.5 |
| Silty Clay | Soft | 10 - 5 | 0.5 |
| Marine Clay | Soft | 20 - 5 | 0.0 |
| Organic Clay | Soft | 20 - 5 | 0.0 |
| Peat | - | 5 - 1 | 0.0 |
### **3.10.6 Drilled Shafts/ Drilled Piers**
Large diameter (more than 600 mm) bored piles are sometimes classified as drilled shaft or drilled piers. They are usually provided with enlarged base called bell. The provisions of this article shall apply to the design of axially and laterally loaded drilled shafts/ drilled piers in soil or extending through soil to or into rock.
#### 3.10.6.1 Application of drilled shaft
Drilled shafts may be considered when spread footings cannot be founded on suitable soil within a reasonable depth and when piles are not economically viable due to high loads or obstructions to driving. Drilled shafts may be used in lieu of spread footings as a protection against scour. Drilled shafts may also be considered to resist high lateral or uplift loads when deformation tolerances are small.
#### 3.10.6.2 Materials for drilled shaft
Shafts shall be cast-in-place concrete and may include deformed bar steel reinforcement, structural steel sections, and/or permanent steel casing as required by design.
#### 3.10.6.3 Embedment for Drilled Shaft
Shaft embedment shall be determined based on vertical and lateral load capacities of both the shaft and sub-surface materials.
#### 3.10.6.4 Batter drilled shaft
The use of battered shafts to increase the lateral capacity of foundations is not recommended due to their difficulty of construction and high cost. Instead, consideration should first be given to increasing the shaft diameter to obtain the required lateral capacity.
#### 3.10.6.5 Selection of soil properties for drilled shaft
Soil and rock properties defining the strength and compressibility characteristics of the foundation materials are required for drilled shaft design.
#### 3.10.6.6 Geotechnical design of drilled shafts
Drilled shafts shall be designed to support the design loads with adequate bearing and structural capacity, and with tolerable settlements. The response of drilled shafts subjected to seismic and dynamic loads shall also be evaluated. Shaft design shall be based on working stress principles using maximum un-factored loads derived from calculations of dead and live loads from superstructures, substructures, earth (i.e., sloping ground), wind and traffic. Allowable axial and lateral loads may be determined by separate methods of analysis.
The design methods presented herein for determining axial load capacity assume drilled shafts of uniform cross section, with vertical alignment, concentric axial loading, and a relatively horizontal ground surface. The effects of an enlarged base, group action, and sloping ground are treated separately.
#### 3.10.6.7 Bearing capacity equations for drilled shaft
The ultimate axial capacity $Q_{ult}$ of drilled shafts shall be determined in accordance with the principles laid for bored piles.
**Cohesive Soil**
Skin friction resistance in cohesive soil may be determined using either the α-method or the β-method as described in the relevant section of driven piles. However, for clay soil, α-method has wide been used by the engineers. This method gives:
$$
f_s = \alpha s_u \tag{6.3.42}
$$
Where,
* $f_s$ = Skin friction
* $s_u$ = undrained shear strength of soil along the shaft
$\alpha$ = adhesion factor =0.55 for undrained shear strength ≤ 190 kPa (4000 psf)
For higher values of $s_u$ the value of $\alpha$ may be taken from Figure 6.3.3 as obtained from test data of previous investigators.
![Adhesion factor alpha for drilled shaft versus normalized undrained shear strength]()
The skin friction resistance should be ignored in the upper 1.5 m of the shaft and along the bottom one diameter of straight shafts because of interaction with the end bearing. If end bearing is ignored for some reasons, the skin friction along the bottom one diameter may be considered. For belled shaft, skin friction along the surface of the bell and along the shaft for a distance of one shaft diameter above the top of bell should be ignored. For end bearing of cohesive soil, the following relations given by Equations 6.3.43 and 6.3.44 are recommended.
$$
f_b = N_cS_u \leq 4000 \text{ kPa} \tag{6.3.43}
$$
Where, $N_c = 6\left[1 + 0.2\left(\dfrac{L}{D_b}\right)\right] \leq 9$
Where,
$f_b$ = End bearing stress
$S_u$ = undrained shear strength of soil along the shaft
$N_c$ = Bearing capacity factor
$L$ = Length of the pile (Depth to the bottom of the shaft)
$D_b$ = Diameter of the shaft base
If the base diameter is more than 1900 mm, the value of $f_b$ from Eq. 6.3.43 could produce settlements greater than 25 mm, which would be unacceptable for most buildings. To keep settlement within tolerable limits, the value of $f_b$ should be reduced to $f_b'$ by multiplying a factor $F_r$ such that:
$$
f_b' = F_rf_b \tag{6.3.44a}
$$
$$
F_r = \frac{2.5}{120\,\omega_1D_b/B_r+\omega_2} \leq 1.0 \tag{6.3.44b}
$$
$$
\omega_1 = 0.0071 + 0.0021\left(\frac{L}{D_b}\right) \leq 0.0015 \tag{6.3.44c}
$$
$$
\omega_2 = 1.59\sqrt{\frac{s_u}{\sigma_r}} \quad 0.5 \leq \omega_2 \leq 1.5 \tag{6.3.44d}
$$
Where,
$B_r$ = Reference width=1 ft = 0.3 m = 12 inch = 300 mm
$\sigma_r$ = Reference stress = 100 kPa = 2000 psf
**Cohesionless Soil**
Skin friction resistance in cohesionless soil is usually determined using the β-method. The relevant equation is reproduced again:
$$
f_s = \beta\sigma_z' \tag{6.3.45}
$$
$$
\beta = K\tan\phi_s \tag{6.3.46}
$$
Where,
$f_s$ = Skin friction
$\sigma_z'$ = Effective vertical stress at mid-point of soil layer
$K$ = Coefficient of lateral earth pressure
$\phi_s$ = Soil shaft interface friction angle
The values of K and $\phi_s$ can be obtained from the chart of Tables 6.3.15, from the soil friction angle, $\phi$ and preconstruction coefficient of lateral earth pressure $K_o$. However, $K_o$ is very difficult to determine. An alternative is to compute β directly using the following empirical relation.
$$
\beta = 1.5 - 0.135\sqrt{\frac{z}{B_r}} \tag{6.3.47}
$$
Where,
*Br* = Reference width=1 ft = 0.3 m = 12 inch = 300 mm
*z* = Depth from the ground surface to the mid-point of the strata
**Table 6.3.15: Typical** $\phi_s/\phi$ ***and*** $K/K_o$ **Values for the Design of Drilled Shaft**
| **Construction Method** | $\phi_s/\phi$ | **Construction Method** | $K/K_o$ |
| ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------- | ----------------------------------------------------------------------------------- | ------- |
| Open hole or temporary casing | 1.0 | Dry construction with minimal side
wall disturbance and prompt
concreting | 1 |
| Slurry method – minimal slurry
cake | 1.0 | Slurry construction – good
workmanship | 1 |
| Slurry method – heavy slurry | 0.8 | Slurry construction – poor | 2/3 |
| cake | | workmanship | |
| Permanent casing | 0.7 | Casing under water | 5/6 |
| The unit end bearing capacity for drilled shaft in cohesionless soils will be less than that for driven piles because of various reasons like soil disturbance during augering, temporary stress relief while the hole is open, larger diameter and depth of influence etc. The reasons are not well defined, as such the following empirical formula developed by Reese and O’ Nell (1989) may be suggested to use to estimate end bearing stress. | | | |
Where,
B4 = Unit bearing resistance
N = Mean SPT value for the soil between the base of the shaft and a depth equal to two times the base diameter below the base. No overburden correction is required (N= N60)
If the base diameter is more than 1200 mm, the value of B4 from Eq. 6.3.48 could produce settlements greater than 25 mm, which would be unacceptable for most buildings. To keep settlement within tolerable limits, the value of B4 should be reduced to B4 *′* by multiplying a factor &7 such that:
Where,
4 =Base diameter of drilled shaft
#### 3.10.6.8 Other methods of evaluating axial load capacity of drilled shaft
A number of other methods are available to estimate the ultimate axial load capacity of drilled shafts. These methods are based on N-values obtained from Standard Penetration Test (SPT) and on angle of internal friction of sand. These methods may also be used to estimate the ultimate load carrying capacity of drilled shafts. Three of these methods are as follows and they are summarized in Appendix G.
* Method based on the Standard Penetration Test (CGS, 1985)
* Method based on Theory of Plasticity (CGS, 1985)
* Tomlinson (1995) Method
#### 3.10.6.9 Factor of safety for drilled shaft
Similar to bored and driven piles, drilled shafts shall be designed for a minimum overall factor of safety of 2.0 against bearing capacity failure (end bearing, side resistance or combined) when the design is based on the results of a load test conducted at the site. Otherwise, it shall be designed for a minimum overall factor of safety 3.0. The minimum recommended overall factor of safety is based on an assumed normal level of field quality control during construction. If a normal level of field quality control cannot be assured, higher minimum factors of safety shall be used. The recommended values of overall factor of safety on ultimate axial load capacity based on specified construction control is presented in Tables 6.3.10a and 6.3.10b.
#### 3.10.6.10 Deformation and settlement of axially loaded drilled shaft
Similar to driven and bored piles, settlement of axially loaded shafts at working or allowable loads shall be estimated using elastic or load transfer analysis methods. For most cases, elastic analysis will be applicable for design provided the stress levels in the shaft are moderate relative to $Q_{ult}$. Analytical methods are similar to that provided in Sec 3.10.1.10 for driven and bored piles. The charts provided in Appendix G may also be used to estimate the settlement of drilled shaft.
#### 3.10.6.11 Drilled shaft in layered soil profile
The short-term settlement of shafts in a layered soil profile may be estimated by summing the proportional settlement components from layers of cohesive and cohesionless soil comprising the subsurface profile.
#### 3.10.6.12 Tolerable movement of drilled shaft
Tolerable axial displacement criteria for drilled shaft foundations shall be developed by the structural designer consistent with the function and type of structure, fixity of bearings, anticipated service life, and consequences of unacceptable displacements on the structure performance. Drilled shaft displacement analyses shall be based on the results of in-situ/laboratory testing to characterize the load-deformation behavior of the foundation materials.
#### 3.10.6.13 Group loading of drilled shaft
**Cohesive Soil**
Evaluation of group capacity of shafts in cohesive soil shall consider the presence and contact of a cap with the ground surface and the spacing between adjacent shafts.
For a shaft group with a cap in firm contact with the ground, $Q_{ult}$ may be computed as the lesser of (1) the sum of the individual capacities of each shaft in the group or (2) the capacity of an equivalent pier defined in the perimeter area of the group. For the equivalent pier, the shear strength of soil shall not be reduced by any factor (e.g., α1) to determine the ? component of $Q_{ult}$, the total base area of the equivalent pier shall be used to determine the QT component of $Q_{ult}$ and the additional capacity of the cap shall be ignored. If the cap is not in firm contact with the ground, or if the soil at the surface is loose or soft, the individual capacity of each shaft should be reduced to ζ times QT for an isolated shaft, where ζ = 0.67 for a center-to-center (CTC) spacing of 3B (where B is the shaft diameter) and ζ = 1.0 for a CTC spacing of 6B. For intermediate spacings, the value of ζ may be determined by linear interpolation. The group capacity may then be computed as the lesser of (1) the sum of the modified individual capacities of each shaft in group, or (2) the capacity of an equivalent pier as stated above.
**Cohesionless Soil**
Evaluation of group capacity of shafts in cohesion soil shall consider the spacing between adjacent shafts. Regardless of cap contact with the ground, the individual capacity of each shaft should be reduced to times QT for an isolated shaft, where ζ = 0.67 for a center-lo-center (CTC) spacing of 3B and ζ = 1.0 for a CTC spacing of 8B. For intermediate spacings, the value of ζ may be determined by linear interpolation. The group capacity may be computed as the lesser of (I) sum of the modified individual capacities of each shaft in the group or (2) capacity of an equivalent pier circumscribing the group including resistance over the entire perimeter and base areas.
#### 3.10.6.14 Drilled shaft in strong soil overlying weak soil
If a group of shafts is embedded in a strong soil deposit which overlies a weaker deposit (cohesionless and cohesive soil), consideration shall be given to the potential for a punching failure of the lip into the weaker soil strata. For this case, the unit tip capacity XH of the equivalent shaft may be determined using the following:
In the above equation X^A is the ultimate unit capacity of an equivalent shaft bearing in the stronger upper layer and XB is the ultimate unit capacity of an equivalent shaft bearing in the weaker underlying soil layer. If the underlying soil unit is a weaker cohesive soil strata, careful consideration shall be given to the potential for large settlements in the weaker layer.
#### 3.10.6.15 Lateral loads on drilled shaft
**Soil Layering**
The design of laterally loaded drilled shafts in layered soils shall be based on evaluation of the soil parameters characteristic of the respective layers
**Ground Water**
The highest anticipated water level shall be used for design
**Scour**
The potential for loss of lateral capacity due to scour shall be considered in the design. If heavy scour is expected, consideration shall be given to designing the portion of the shaft that would be exposed as a column. In all cases, the shaft length shall be determined such that the design structural load can be safely supported entirely below the probable scour depth.
**Group action**
There is no reliable rational method for evaluating the group action for closely spaced, laterally loaded shafts. Therefore, as a general guide, drilled shaft with diameter B in a group may be considered to act individually when the center-tocenter (CTC) spacing is greater than 2.5B in the direction normal to loading, and CTC > 8B in the direction parallel to loading. For shaft layout not conforming to these criteria, the effects of shaft interaction shall be considered in the design. As a general guide, the effects of group action for in-line CTC \<8B may be considered using the ratios (CGS, 1985) appearing as below, Table 6.3.16:
**Table 6.3.16: Ratio of Group and Single Plie Shaft Resistance**
| **Centre to Centre Shaft** | **Ratio of Lateral Resistance of** |
| ---------------------------------------- | ---------------------------------- |
| **Spacing for In-line**
**Loading** | **Shaft in Group to Single Shaft** |
| 8B | 1.00 |
| 6B | 0.70 |
| 4B | 0.40 |
| 3B | 0.25 |
| **Cyclic Loading** | |
The effects of traffic, wind, and other non-seismic cyclic loading on the loaddeformation behavior of laterally loaded drilled shafts shall be considered during design. Analysis of drilled shafts subjected to cyclic loading may he considered in the COM624 analysis (Reese et. al., 1984).
**Combined Axial and Lateral Loading**
The effects of lateral loading in combination with axial loading shall be considered in the design. Analysis of drilled shafts subjected to combined loading may be considered in the COM624 analysis (Reese et. al., 1984).
**Sloping Ground**
For drilled shafts which extend through or below sloping ground. The potential for additional lateral loading shall be considered in the design. The general method of analysis developed by Borden and Gabr (1987) may be used for the analysis of shafts instable slopes. For shafts in marginally stable slopes. Additional consideration should be given for smaller factors of safety against slope failure or slopes showing ground creep, or when shafts extend through fills overlying soft foundation soils and bear into more competent underlying soil or rock formations. For unstable ground, detailed explorations, testing and analysis are required to evaluate potential additional lateral loads due to slope movements
**Tolerable Lateral Movements**
Tolerable lateral displacement criteria for drilled shaft foundations shall be developed by the structural designer consistent with the function and type of structure, fixity, anticipated service life, and consequences of unacceptable displacements on the structure performance. Drilled shaft lateral displacement analysis shall be based on the results of in-situ and/or laboratory testing to characterize the load-deformation behavior of the foundation materials.
#### 3.10.6.16 Uplift loads on drilled shaft
Uplift capacity shall rely only on side resistance in conformance with related articles for driven piles. If the shaft has an enlarged base, ? shall be determined in conformance with related articles for driven piles.
#### 3.10.6.17 Consideration of vertical ground movement
The potential for external loading on a shaft by vertical ground movement (i.e., negative skin friction down-drag due to settlement of compressible soil or uplift due to heave of expansive soil) shall be considered as a part of design. For design purposes, it shall be assumed that the full magnitude of maximum potential vertical ground movement occurs.
#### 3.10.6.18 Negative skin friction
Evaluation of negative skin friction shall include a load-transfer method of analysis to determine the neutral point (i.e., point of zero relative displacement) and load distribution along shaft (e.g., Reese and O'Neill, 1988). Due to the possible time dependence associated with vertical ground movement, the analysis shall consider the effect of time on load transfer between the ground and shaft and the analysis shall be performed for the time period relating to the maximum axial load transfer to the shaft. Evaluation of negative skin friction shall include a load-transfer method of analysis to determine the neutral point (i.e., point of zero relative displacement) and load distribution along shaft (e.g., Reese and O'Neill, 1988). Due to the possible time dependence associated with vertical ground movement, the analysis shall consider the effect of time on load transfer between the ground and shaft and the analysis shall be performed for the time period relating to maximum axial load transfer to the shaft.
#### 3.10.6.19 Expansive soils
Shafts designed for and constructed in expansive soil shall extend to a sufficient depth into moisture-stable soils to provide adequate anchorage to resist uplift movement in addition; sufficient clearance shall be provided between the ground surface and underside of caps or beams connecting shafts to preclude the application of uplift loads at the shaft/cap connection from swelling ground conditions.
#### 3.10.6.20 Dynamic/seismic design of drilled shaft
Refer to Seismic Design section of this Code and Lam and Martin (1986a; 1986b) for guidance regarding the design of drilled shafts subjected to dynamic and seismic loads.
#### 3.10.6.21 Structural shaft design, shaft dimensions and shaft spacing
Drilled shafts shall be designed to resist failure loads to insure that the shaft will not collapse or suffer loss of serviceability due to excessive stress and/or deformation.
**Dimensions**
All shafts should be sized in 50 mm increments with a minimum shaft diameter of 600 mm. The diameter of columns supported by shafts shall be less than or equal to the shaft diameter B.
**Center to Center Spacing**
The center-to-center spacing of drilled shafts of diameter B should be 3B or greater to avoid interference between adjacent shafts during construction. If closer spacing is required, the sequence of construction shall be specified and the interaction effects between adjacent shafts shall be evaluated by the designer.
**Reinforcement**
Where the potential for lateral loading is insignificant, drilled shafts need to be reinforced for axial loads only. Those portions of drilled shafts that are not supported laterally shall be designed as reinforced concrete columns in accordance with relevant sections in structural design part of the Code and the reinforcing steel shall extend a minimum of 5 m below the plane where the soil provides adequate lateral restraint. Where permanent steel casing is used and the shell is smooth pipe and more than 3 mm in thickness, it may be considered as load carrying in the absence of corrosion.
The design of longitudinal and spiral reinforcement shall be in conformance with the requirements of the relevant sections of the structural design part of the Code. Development of length of deformed reinforcement shall be in conformance with the relevant sections of the structural design part of the Code.
**Longitudinal Bar Spacing**
The minimum clear distance between longitudinal reinforcement shall not be less than 3 times the bar diameter nor 3 times the maximum aggregate size. If bars are bundled in forming the reinforcing cage, the minimum clear distance between longitudinal reinforcement shall not be less than 3 times the diameter of the bundled bars. Where heavy reinforcement is required, consideration may be given to an inner and outer reinforcing cage.
**Splices**
Splices shall develop the full capacity of the bar in tension and compression. The location of splices shall be staggered around the perimeter of the reinforcing cage so as not to occur at the same horizontal plane. Splices may be developed by lapping, welding, and special approved connectors. Splices shall be in conformance with the relevant sections of the structural design part of the Code.
**Transverse Reinforcement**
Transverse reinforcement shall be designed to resist stresses caused by fresh concrete flowing from inside the cage to the side of the excavated hole. Transverse reinforcement may be constructed of hoops or spiral steel.
**Handling Stresses**
Reinforcement cages shall be designed to resist handling and placement stresses.
**Reinforcement Cover**
The reinforcement shall be placed a clear distance of not less than 50 mm from the permanently cased or 75 mm from the uncased sides. When shafts are constructed in corrosive or marine environments, or when concrete is placed by the water or slurry displacement methods, the clear distance shall not be less than 100 mm for uncased shafts and shafts with permanent casings not sufficiently corrosion resistant.
The reinforcement cage shall be centered in the hole using centering devices. All steel centering devices shall be epoxy coated.
**Reinforcement into Superstructure**
Sufficient reinforcement shall be provided at tit junction of the shaft with the superstructure to make a suitable connection. The embedment of the reinforcement into the cap shall be in conformance with relevant articles of the structural design part of the Code.
#### 3.10.6.22 Enlarged base of drilled shaft
Enlarged bases shall be designed to insure that plain concrete is not overstressed. The enlarged base shall slope at a side angle not less than 30 degrees from the vertical and have a bottom diameter not greater than 3 times diameter of the shaft. The thickness of the bottom edge of enlarged base shall not be less than 150 mm.
#### 3.10.6.23 Construction of drilled shaft
Drilled shafts may be constructed using the dry, casing, or wet method of construction, or a combination of methods. In every case, excavation of hole, placement of concrete, and all other aspects of shaft construction shall be performed in conformance with the provisions of this Code.
The load capacity and deformation behavior of drilled shafts can be greatly affected by the quality and methods of construction. The effects of construction methods are incorporated in design by application of factor of safety consistent with the expected construction methods and level of field quality control measures undertaken as described in the relevant sections for driven piles.
Where the spacing between shafts in a group is restricted, consideration shall be given to the sequence of construction to minimize the effect of adjacent shaft construction operations on recently constructed shafts. The following construction procedure shall be followed:
* (i) Place permanent/temporary steel casing in position and embed casing toe into firm strata.
* (ii) Bore and excavate inside the steel casing down to casing toe level, or to a level approved, and continue excavation to final pile tip level using drilling mud. The fluid level inside casings shall at all times be at least 2 metres higher than outside the casings.
* (iii) Carefully clean up all mud or sedimentation from the bottom of borehole.
* (iv) Place reinforcement cage, inspection pipes etc.
* (v) Concrete continuously under water, or drilling fluid, by use of the tremie method.
* (vi) After hardening, break out the top section of the concrete pile to reach sound concrete.
In drilling of holes for all piles, bentonite and any other material shall be mixed thoroughly with clean water to make a suspension which shall maintain the stability of the pile excavation for the period necessary to place concrete and complete construction. The control tests shall cover the determination of' density, viscosity, gel strength and pH values. Bentonite slurry shall meet the Specifications as shown in Table 6.3.17.
**Table 6.3.17: Specifications of Bentonite Slurry**
| **Item to be Measured** | **Range of Results**
**at 20**°**C** | **Test Method** |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------- | ------------------------------------------------------------------ |
| Density during drilling to | greater than 1.05 | Mud density Balance (ASTM D4380) |
| support excavation | g/ml | |
| Density prior to concreting | less than 1.25 g/ml | Mud density Balance (ASTM D4380) |
| Viscosity | 30 - 90 seconds | Marsh Cone Method (ASTM D6910) |
| pH | 9.5 to 12 | pH indicator paper strips or electrical pH
meter (ASTM D4972) |
| Liquid limit | > 450% | Casagrande apparatus (ASTM D4318) |
| Temporary casing of approved quality or an approved alternative method shall be used to maintain the stability of pile excavations, which might otherwise collapse. Temporary casings shall be free from significant distortion. | | |
Where a borehole is formed using drilling fluid for maintaining the stability of a boring, the level of the water or fluid in the excavation shall be maintained so that the water or fluid pressure always exceeds the pressure exerted by the soils and external ground water. The water or fluid level shall be maintained at a level not less than 2 m above the level of ground water.
The reinforcement shall be placed as indicated on the Drawings. Reinforcement in the form of a cage shall be assembled with additional support, such as Spreader forks and lacings, necessary to form a rigid cage. Hoops, links or helical reinforcement shall fit closely around the main longitudinal bars and be bound to them by approved wire, the ends of which shall be turned into the interior of the pile or pour. Reinforcement shall be placed and maintained in position. The cover to all reinforcement for pile cap and bored cast in place pile shall be not less than 75 mm.
Joints in longitudinal steel bars shall be permitted unless otherwise specified. Joints in reinforcement shall be such that the full strength of the bar is effective across the joint and shall be made so that there is no relative displacement of the reinforcement during the construction of the pile. Joints in longitudinal bars in piles with tension (for instance for test loading) shall be carried out by welding or other approved method.
Concrete to be placed under water or drilling fluid shall be placed by tremie equipment and shall not be discharged freely into the water or drilling fluid. The tremie equipment shall be designed to minimize the occurrence of entrapped air and other voids, so that it causes minimal surface disturbance, which is particularly important when a concrete-water interface exists. It shall be so designed that external projections are minimised, allowing the tremie to pass through reinforcing cages without causing damage. The internal face of the pipe of the tremie shall be free from projections. The tremie pipes shall meet the following requirements:
* (i) The tremie pipes shall be fabricated of heavy gage steel pipe to withstand all anticipated handling stress. Aluminium pipe shall not be used for placing concrete.
* (ii) Tremie pipes should have a diameter large enough to ensure that aggregates-caused blockage will not occur. The diameter of the tremie pipe shall be 200 mm to 300 mm.
* (iii) The tremie pipes shall be smooth internally.
* (iv) Since deep placement of concrete will be carried out, the tremie shall be made in sections/lengths with detachable joints that allow the upper sections/lengths to be removed as the placement progresses.
* (v) Sections may be joined by flanged, bolted connections (with gaskets) or may be screwed together. Whatever joint technique is selected, joints between tremie sections must be watertight. The joint system selected shall be tested for water tightness before beginning of concrete placement.
* (vi) The joint system to be used shall need approval of the Engineer.
* (vii) The tremie pipe should be marked to allow quick determination of the distance from the surface of the water to the mouth of the tremie.
* (viii) The tremie should be provided with adequately sized funnel or hopper to facilitate transfer of sufficient concrete from the delivery device to the tremie.
Before placing concrete, it shall be ensured that there is no accumulation of silt, other material, or heavily contaminated bentonite suspension at the base of the boring, which could impair the free flow of concrete from the pipe of the tremie. Flushing of boreholes before concreting with fresh drilling fluid/mud is preferred. A sample of the bentonite suspension shall be taken from the base of the boring using an approved sampling device. If the specific gravity of the suspension exceeds 1.25, the placing of concrete shall not proceed. In this event the Contractor shall modify the mud quality. During and after concreting, care shall be taken to avoid damage to the concrete from pumping and dewatering operations.
The hopper and pipe of the tremie shall be clean and watertight throughout. The pipe shall extend to the base of the boring and a sliding plug or barrier shall be placed in the pipe to prevent direct contact between the first charge of concrete in the pipe of the tremie and the water or drilling fluid. The pipe shall at all times penetrate the concrete, which has previously been placed and shall not be withdrawn from the concrete until completion of concreting. The bottom of the tremie pipe shall be embedded in the fresh concrete at least 2.0 m and maintained at that depth throughout concreting. At all times a sufficient quantity of concrete shall be maintained within the pipe to ensure that the pressure from it exceeds that from the water or drilling fluid.
To ensure the quality of concrete being free from mud, clay lumps or any other undesirable materials mixed with concrete at the top portion of the pile, fresh concrete shall be overflowed sufficiently at the end of the each pour. The level of concrete poured at the end of concreting operation shall be at least 600 mm higher than the elevation of the pile at cut-off.
#### 3.10.6.24 Concreting of drilled shaft
In drilled shafts/cast-in-situ bored piles, concrete shall be placed only after excavation has been completed, inspected and accepted, and steel reinforcement accurately placed and adequately supported. Concrete shall be placed in one continuous operation in such a manner as to ensure the exclusion of any foreign matter and to secure a full sized shaft. Concrete shall not be placed through water except where tremie methods are approved. When depositing concrete from the top of the pile, the concrete shall not be chuted directly into the pile but shall be poured in a rapid and continuous operation through a funnel hopper centred at the top of the pile.
For large diameter holes concrete may be placed by tremie or by drop bottom bucket; for small diameter boreholes a tremie shall be utilized. In tremie concreting, toe of the tremie shall be set at a maximum of 150 mm above the bottom of the borehole. Maximum permissible siltation in bore hole prior to start of concrete operation shall be 75 mm. A slump of 125 mm to 150 mm shall be maintained for concreting by tremie. In case of tremie concreting for piles of smaller diameter and length up to 10 m, the minimum cement content shall be 350 kg/m3 of concrete. For larger diameter and/or deeper piles, the minimum cement content shall be 400 kg/m3 of concrete. See relevant sections of the Code for further specification.
For uncased concrete piles, if pile shafts are formed through unstable soil and concrete is placed in an open drill hole, a steel liner shall be inserted in the hole prior to placing concrete. If the steel liner is withdrawn during concreting, the level of concrete shall be maintained above the bottom of the liner to a sufficient height to offset any hydrostatic or lateral earth pressure.
If concrete is placed by pumping through a hollow stem auger, the auger shall not be permitted to rotate during withdrawal and shall be withdrawn in a steady continuous motion. Concrete pumping pressures shall be measured and shall be maintained high enough at all times to offset hydrostatic and lateral earth pressure. Concrete volumes shall be measured to ensure that the volume of concrete placed in each pile is equal to or greater than the theoretical volume of the hole created by the auger. If the installation process of any pile is interrupted or a loss of concreting pressure occurs, the hole shall be redrilled to original depth and reformed.
Augured cast-in-situ pile shall not be installed within 6 pile diameters centre to centre of a pile filled with concrete less than 24 hours old. If concrete level in any completed pile drops, the pile shall be rejected and replaced. Bored cast-in-situ concrete piles shall not be drilled/bored within a clear distance of 3 m from an adjacent pile with concrete less than 48 hours old. For under-reamed piles, the slump of concrete shall range between 100 mm and 150 mm for concreting in water free holes.
For concreting under water, the concrete shall contain at least 10 percent more cement than that required for the same mix placed in the dry. The amount of coarse aggregate shall be not less than one and a half times, nor more than two times, that of the fine aggregate. The materials shall be so proportioned as to produce a concrete having a slump of not less than 100 mm, nor more than 150 mm, except where plasticizing admixtures is used in which case, the slump may be 175 mm.
Successful placement of concrete under water requires preventing flow of water across or through the placement site. Once flow is controlled, the tremie placement consists of the following three basic steps:
* (i) The first concrete placed is physically separated from the water by using a “rabbit” or go-devil in the pipe, or by having the pipe mouth capped or sealed and the pipe dewatered.
* (ii) Once filled with concrete, the pipe is raised slightly to allow the “rabbit” to escape or to break the end seal. Concrete will then flow out and develop a mound around the mouth of the pipe. This is termed as “establishing a seal”.
* (iii) Once the seal is established, fresh concrete is injected into the mass of existing concrete.
Two methods are normally used for the placement of concrete using tremie pipe, namely, the capped tremie pipe approach and the “rabbit” plug approach. In the capped tremie approach the tremie pipe should have a seal, consisting of a bottom plate that seals the bottom of the pipe until the pipe reaches the bottom of excavation. The tremie pipe should be filled with enough concrete before being raised off the bottom. The tremie pipe should then be raised a maximum of 150 mm (6 inch) to initiate flow. The tremie pipe should not be lifted further until a mound is established around the mouth of the tremie pipe. Initial lifting of the tremie should be done slowly to minimize disturbance of material surrounding the mouth of the tremie.
In the “rabbit” plug approach, open tremie pipe should be set on the bottom, the “rabbit” plug inserted at the top and then concrete should be added to the tremie slowly to force the “rabbit” downward separating the concrete from the water. Once the tremie pipe is fully charged and the “rabbit” reaches the mouth of the tremie, the tremie pipe should be lifted a maximum of 150 mm (6 inch) off the bottom to allow the “rabbit” to escape and to start the concrete flowing. After this, a tremie pipe should not be lifted again until a sufficient mound is established around the mouth of the tremie.
Tremies should be embedded in the fresh concrete a minimum of 1.0 to 1.5 m (3 to 5 ft) and maintained at that depth throughout concreting to prevent entry of water into the pipe. Rapid raising or lowering of the tremie pipe should not be allowed. All vertical movements of the tremie pipe must be done slowly and carefully to prevent “loss of seal”. If “loss of seal” occurs in a tremie, placement of concrete through the tremie must be halted immediately. The tremie pipe must be removed and the end plate must be restarted using the capped tremie approach. In order to prevent washing of concrete in place, a “rabbit” plug approach must not be used to restart a tremie after “loss of seal”.
Means of raising or lowering tremie pipes and of removing pipes smoothly without loss of concrete and without disturbing placed concrete or trapping air in the concrete shall be provided. Pipes shall not be moved horizontally while they are embedded in placed concrete or while they have concrete within them.
Underwater concrete shall be placed continuously for the whole of a pour to its full depth approved by the Engineer, without interruption by meal breaks, change of shift, movements of placing positions, and the like. Delays in placement may allow the concrete to stiffen and resist flow once placement resumes. The rate of pour from individual tremie shall be arranged so that concrete does not rise locally to a level greater than 500 mm above the average level of the surrounding concrete.
Tremie blockages which occur during placement should be cleared extremely carefully to prevent loss of seal. If a blockage occurs, the tremie should be quickly raised 150 to 600 mm (6 inch to 2 ft) and then lowered in an attempt to dislodge the blockage. The depth of pipe embedment must be closely monitored during all such attempts. If the blockage cannot be cleared readily, the tremie shall be removed, cleared, resealed, and restarted.
The volume of concrete in place should be monitored throughout the placement. Underruns are indicative of loss of tremie seal since the washed and segregated aggregates will occupy a greater volume. Overruns are indicative of loss of concrete from the inside of the steel pile.
## **3.11 Field Tests for Driven Piles and Drilled Shafts**
### **3.11.1 Integrity Test**
Low strain integrity testing of piles is a tool for quality control of long structural elements that function in a manner similar to foundation piles, regardless of their method of installation, provided that they are receptive to low strain impact testing. The test provides velocity (and optionally force) data, which assists evaluation of pile integrity and pile physical dimensions (i.e., cross-sectional area, length), continuity and consistency of pile material. The test does not give any information regarding the pile bearing capacity or about pile reinforcement. Integrity test principles have been well documented in literature (ASTM 5882; Klingmuller, 1993). There exist two methods of integrity testing, namely, Pulse Echo Method (PEM) and Transient Response Method (TRM). In Pulse Echo Method, the pile head motion is measured as a function of time. The time domain record is then evaluated for pile integrity. In Transient Response Method, the pile head motion and force (measured with an instrumented hammer) are measured as a function of time. The data are then evaluated usually in the frequency domain.
In order to check the structural integrity of the piles Integrity tests shall be performed on the piles in accordance with the procedure outlined in ASTM D5882. The test is carried out by pressing a transducer onto a pile top while striking the pile head with a hand hammer. The Sonic Integrity Testing (SIT)-system registers the impact of the hammer followed by the response of the pile and shows the display. If instructed by the operator, the signal will be stored in the memory of the SIT-system together with other information, such as pile number, date, time, site, amplification factor, filter length etc. The reflectograms are horizontally scaled and vertically amplified to compensate external soil friction, which facilitate the interpretation. Consequently, the reflection of the pile toe matches the length of the pile which will be confirmed by the SIT-system. In case of any defects, the exact location can be determined from the graph on the display.
For any project where pile has been installed, integrity tests shall be performed on 100% of the piles. Integrity testing may not identify all imperfections, but it can be used in identifying major defects within effective length. In literature, there are many examples that highlight success of low strain integrity testing (Klingmuller, 1993).
Factors Influencing Implication of Pile Integrity Test
* (a) This sonic echo pile integrity testing or dynamic response method is based on measuring (or observing on an oscilloscope) the time it takes for a reflected compression stress wave to return to the top of the pile.
* (b) Some waves will be reflected by a discontinuity in the pile shaft. When the compressive strength is known for the pile material involved, the depth to the discontinuity and the pile length can be determined.
* (c) On the other hand, area of pile shaft and hence its diameter, is determined from impedance of wave response, while impedance in any section is a function of elastic modulus of pile material, shaft area and wave velocity propagating through that section. If the concrete material is uniform throughout the pile length, elastic modulus and the wave velocity (provided disturbance from other source of vibration nearby is insignificant) are constant for that pile. In that case, changes in impedance usually indicate changes of pile cross-sectional area.
* (d) While evaluating pile integrity (i.e., pile length and shaft diameter), the wave velocity is assumed to be constant throughout pile length. Thus, the reliability of integrity evaluation entirely depends on the pile material and its uniformity throughout shaft length while casting was done. The length and diameter obtained from pile integrity test is an indication of the actual length and diameter of the tested piles.
* (e) Besides, this test can only assess shaft integrity and gives no information for pile bearing capacity determination. However, if a large number of piles are tested, it is generally easy to focus the piles having unusual responses. Therefore, whenever an integrity testing is contemplated, consideration must be given to the limitations of the various methods/process of pile installation (i.e. pile driving or casting) and the possible need for further investigation (such as pile load test) to check the results of such testing.
* (f) It should be noted here that pile integrity test is an indicative test about the length and quality of concrete in the pile. This test does not give any idea about its actual load capacity. It is usually suggestive to substantiate the findings of integrity test by excavation or pull out of the pile to facilitate decisions about final acceptance or rejection of any pile. Because of the large cost involved in a pile load test, the necessity of integrity test in facilitating the selection of piles for load test is a rational approach for quality and safety assurance of piled foundations.
### **3.11.2 Axial Load Tests for Compression**
Where accurate estimate of axial load carrying capacity of a pile is required tests in accordance with "Standard Test Method for Deep Foundations Under Static Axial Compressive Load", (ASTM D1143) or equivalent shall be performed on individual piles. For a major project, at least 2% of piles (test piles plus service piles) shall be tested in each area of uniform subsoil conditions. Where necessary, additional piles may be load tested to establish the safe design capacity. The ultimate load carrying capacity of a single pile may be determined with reasonable accuracy from load testing. The load test on a pile shall not be carried out earlier than 4 (four) weeks from the date of casting the pile. A minimum of one pile at each project shall be load tested for bored cast-in-situ piles.
Two principal types of test may be used for compression loading on piles - the constant rate of penetration (CRP) test and the maintained load (ML) test. The CRP test was developed by Whitaker (1963). The CRP method is essentially a test to determine the ultimate load on a pile and is therefore applied only to preliminary test piles or research type investigations where fundamental pile behaviour is being studied. In this test the compressive force is progressively increased to cause the pile to penetrate the soil at constant rate until failure occurs. The rate of penetration selected usually corresponds to that of shearing soil samples in unconfined compression tests. However, rate does not affect results significantly. In CRP test the recommended rates of penetration are 0.75 mm/min for friction piles in clay and 1.55 mm/min for piles end bearing in granular soil. The CRP test shall not be used for checking compliance with specification requirements for maximum settlement at given stages of loading.
Maintained load (ML) test is so far the most usual one in practice. In the ML test the load is increased in stages to 1.5 times or twice the working load with time settlement curve recorded at each stage of loading and unloading. The general procedure is to apply static loads in increments of 25% of the anticipated design load. The ML test may also be taken to failure by progressively increasing the load in stages. In the ML test, the load test arrangements as specified in (ASTM D1143) shall be followed. According to ASTM D1143 each load increment is maintained until the rate of settlement is not greater than 0.25 mm/hr or 2 hours is elapsed, whichever occurs first. After that the next load increment is applied. This procedure is followed for all increments of load. After the completion of loading if the test pile has not failed the total test load is removed any time after twelve hours if the butt settlement over one hour period is not greater than 0.25 mm otherwise the total test load is kept on the pile for 24 hours. After the required holding time, the test load is removed in decrement of 25% of the total test load with 1 hour between decrement. If failure occurs, jacking the pile is continued until the settlement equals 15% of the pile diameter or diagonal dimension. Selection of an appropriate load test method shall be based on an evaluation of the anticipated types and duration of loads during service, and shall include consideration of the following:
* (i) The immediate goals of the load test (i.e., to proof load the foundation and verify design capacity)
* (ii) The loads expected to act on the production foundation (compressive and/or uplift, dead and/or live), and the soil conditions predominant in the region of concern.
* (iii) The local practice or traditional method
As a minimum, the written test procedures should include the following:
* (i) Apparatus for applying loads including reaction system and loading system.
* (ii) Apparatus for measuring movements.
* (iii) Apparatus for measuring loads.
* (iv) Procedures for loading including rates of load application, load cycling and maximum load.
* (v) Procedures for measuring movements.
* (vi) Safety requirements.
* (vii) Data presentation requirements and methods of data analysis.
* (viii) Drawings showing the procedures and materials to be used to construct the load test apparatus.
#### 3.11.2.1 Load test evaluation methods for axial compressive
A number of arbitrary or empirical methods are used to serve as criteria for determining the allowable and ultimate load carrying capacity from pile load test. Some are based on maximum permissible gross or net settlement as measured at the pile butt while the others are based on the performance of the pile during the progress of testing (Chellis, 1961; Whitaker, 1976; Poulos and Davis, 1980; Fuller, 1983). It is recommended to evaluate the load carrying capacity of piles and drilled shaft using any of the following methods along with the arbitrary methods:
* (a) Davission Offset Limit
* (b) British Standard Institution Criterion
* (c) Indian Standard Criteria
* (d) Butler-Hoy Criterion
* (e) Brinch-Hansen 90% Criterion
* (f) Other methods approved by the Geotechnical Engineer
The recommended criteria to be used for evaluating the ultimate and allowable load carrying capacity of piles and drilled shaft are summarized below.
(a) A very useful method of computing the ultimate failure load has been reported by Davisson (1973). This method is based on offset method that defines the failure load. The elastic shortening of the pile, considered as point bearing, free standing column, is computed and plotted on the loadsettlement curve, with the elastic shortening line passing through the origin. The slope of the elastic shortening line is 20o . An offset line is drawn parallel to the elastic line. The offset is usually 0.15 inch plus a quake factor, which is a function of pile tip diameter. For normal size piles, this factor is usually taken as 0.1D inch, where D is the diameter of pile in foot. The intersection of offset line with gross load-settlement curve determines the arbitrary ultimate failure load. Davisson method is too restrictive for drilled piles, unless the resistance is primarily friction. This method is recommended for driven precast piles.
* (b) Terzaghi (1942) reported that the ultimate load capacity of a pile may be considered as that load which causes a settlement equal to 10% of the pile diameter. However, this criterion is limited to a case where no definite
failure point or trend is indicated by the load-settlement curves. This criterion has been incorporated in BS 8004 ”Code of Practice for Foundations” which recommends that the ultimate load capacity of pile should be that which causes the pile to settle a depth of 10% of pile width or diameter.
* (c) The allowable load capacity of pile should be 50% of the final load, which causes the pile to settle a depth of 10% of pile width or diameter (BS 8004).
* (d) Ultimate load capacity of pile is smaller of the following two (IS: 2911 Part-4):
* (i) Load corresponding to a settlement equal to 10% of the pile diameter in the case of normal uniform diameter pile or 7.5% of base diameter in case of under-reamed or large diameter cast in-situ pile.
* (ii) Load corresponding to a settlement of 12 mm.
* (e) Allowable load capacity of pile is smaller of the following (IS: 2911 Part-4):
* (i) Two thirds of the final load at which the total settlement attains a value of 12 mm.
* (ii) Half of the final load at which total settlement equal to 10% of the pile diameter in the case of normal uniform diameter pile or 7.5% of base diameter in case of under-reamed pile.
* (f) Butler and Hoy (1977) states that the intersection of tangent at initial straight portion of the load-settlement curve and the tangent at a slope point of 1.27 mm/ton determines the arbitrary ultimate failure load.
* (g) The Brinch Hansen (1963) proposed a definition for ultimate load capacity as that load for which the settlement is twice the settlement under 90 percent of the full test load.
* (h) Where failure occurs, the ultimate load may be taken to calculate the allowable load using a factor of safety of 2.0 to 2.5.
For load test on working pile/shaft, the safe load should be determined using the criteria of Sec 3.10.1.16.
#### 3.11.2.2 Some factors influencing interpretations of load test results for axial compression
The following factors should be taken into account while interpreting the test results from pile load tests:
* (a) Potential residual loads (strains) in the pile which could influence the interpreted distribution of load along the pile shaft.
* (b) Possible interaction of friction loads from test pile with downward friction transferred to the soil from reaction piles obtaining part or all of their support in soil at levels above the tip level of the test pile.
* (c) Changes in pore water pressure in the soil caused by pile driving, construction fill and other construction operations which may influence the test results for frictional support in relatively impervious soils such as clay and silt.
* (d) Differences between conditions at time of testing and after final construction such as changes in grade groundwater level.
* (e) Potential loss of soil resistance from events such as excavation, or scour, or both of surrounding soil.
* (f) Possible difference in the performance of a pile in a group or of a pile group from that of a single pile.
* (g) Effect on long term pile performance of factors such as creep, environmental effects on pile material, friction loads from swelling soils and strength losses.
* (h) Type of structure to be supported, including sensitivity of structure to movement and relations between live and dead loads.
* (i) Special testing procedures which may be required for the application of certain acceptance criteria or methods of interpretation.
* (j) Requirement of all conditions for non-tested piles be basically identical to those for test pile including such thing as subsurface conditions, pile type, length, size and stiffness, and pile installation methods and equipment so that application or extrapolation of the test results to such other piles is valid.
### **3.11.3 Load Test for Uplift Capacity of Driven Pile, Bored Pile and Drilled Shaft**
Where required by the design, the uplift capacity of pile and drilled shaft shall be determined by an approved method or analysis based on a minimum factor of safety of three or by load tests conducted in accordance with ASTM D3689 (Standard Test Method for Deep Foundations Under Static Axial Tensile Load). The maximum allowable uplift load shall not exceed the ultimate load capacity as determined using the results of load test conducted in accordance with ASTM D3689, divided by a factor of safety of 2.0. Where uplift is due to wind or seismic loading, the minimum factor of safety shall be 2.0 where capacity is determined by an analysis and 1.5 where capacity is determined by load tests.
For group pile subjected to uplift, the allowable working uplift load for the group shall be calculated by an approved method of analysis where the piles in the group are placed at centre-to-centre spacing of at least 2.5 times the least horizontal dimension of the largest pile, the allowable working uplift load for the group is permitted to be calculated as the lesser of the two:
* (i) The proposed individual working load times the number of piles in the group.
* (ii) Two-thirds of the effective weight of the group and the soil contained within a block defined by the perimeter of the group and the embedded length of the pile.
* (iii) One-half the effective weight of the pile group and the soil contained within a block defined by the perimeter of the group and the embedded pile length plus one-half the total soil shear on the peripheral surface of the group
Uplift or tension test on piles subject to tension/uplift shall be performed by a continuous rate of uplift (CRU) or an incremental loading (i.e. ML) test. Where uplift loads are intermittent or cyclic in character, as in wave loading on a marine structure, it is recommended to adopt repetitive loading on the test pile. The tests shall be performed in accordance with ASTM D3689. Safe load shall be taken as the least of the following:
* (a) Two thirds of the load at which the total displacement (pile top) is 12 mm or the load corresponding to a specified permissible uplift, and
* (b) Half of the load at which the load displacement curve shows a clear break (downward trend).
The initial load test (on test pile/shaft) shall be carried out up to twice the estimated design load or the load displacement curve shows a clear break. The routine test on working pile shall be done up to one and a half times the design load or 12 mm total displacement whichever occurred earlier.
### **3.11.4 Load Tests for Lateral Load Capacity**
Load test for lateral capacity shall be performed as per the procedure of ASTM D3966. Safe load capacity shall be determined as per criteria mentioned in 3.10.1.20 for driven piles.
**Division C: Additional Considerations in Planning, Design and Construction of Building Foundations (Sections 3.12 To 3.22)**
## **3.12 Excavation**
Excavation for building foundation or for other purpose shall be done in a safe manner so that no danger to life and property prevails at any stage of the work or after completion. The requirements of this Section shall be satisfied for all such works in addition to those of Sec 3.3 of Part 7.
Permanent excavations shall have retaining walls of sufficient strength made of steel, masonry, or reinforced concrete to retain the embankment, together with any surcharge load.
Excavations for any purpose shall not extend within 300 mm under any footing or foundation, unless such footing or foundation is properly underpinned or protected against settlement, beforehand.
The design and construction of deep excavation work more than 6 m depth or excavation in soft soil or erratic soil must be checked by a competent Geotechnical Engineer.
### **3.12.1 Notice to Adjoining Property**
Prior to any excavation close to an adjoining building in another property, a written notice shall be given to the owner of the adjoining property at least 10 days ahead of the date of excavation. The person undertaking the excavation shall, where necessary, incorporate adequate provisions and precautionary measures to ensure safety of the adjoining property and shall supply the details of such measures in the notice to the owner of the adjoining property. He shall obtain approval of the
Authority regarding the protective provisions, and permission of the owner of the adjoining property regarding the proposed excavation in writing. The protective measures shall incorporate the following:
* (i) Where the level of the foundations of the adjoining structure is at or above the level of the bottom of the proposed excavation, the vertical load of the adjoining structure shall be supported by proper foundations, underpinning, or other equivalent means.
* (ii) Where the level of the foundations of the adjoining structure is below the level of the bottom of the proposed excavation, provision shall be made to support any increased vertical or lateral load on the existing adjoining structure caused by the new construction.
If on giving the required notice, incorporating or proposing to incorporate the protective provisions which have duly been approved by the Authority, the owner of the adjoining property refuses to permit the proposed excavation or to allow necessary access and other facilities to the person undertaking the excavation for providing the necessary and approved protection to the adjoining property, the responsibility for any damage to the adjoining property due to excavation shall be that of the owner of the adjoining property.
### **3.12.2 Excavation Work**
Every excavation shall be provided with safe means of entry and exit kept available at all times. When an excavation has been completed, or partly completed and discontinued, abandoned or interrupted, or the required permits have expired, the lot shall be filled and graded to eliminate all steep slopes, holes, obstructions or similar sources of hazard. Fill material shall consist of clean, noncombustible substances. The final surface shall be graded in such a manner as to drain the lot, eliminate pockets, prevent accumulation of water, and preclude any threat of damage to the foundations on the premises or on the adjoining property.
#### 3.12.2.1 Methods of protection
**Shoring, Bracing and Sheeting**
With the exception of rock cuts, the sides of all excavations, including related or resulting embankments, 1.5 m or greater in depth or height measured from the level of the adjacent ground surface to the deepest point of excavation, shall be protected and maintained by shoring, bracing and sheeting, sheet piling, or other retaining structures. Alternatively, excavated slopes may be inclined not steeper than 1:1, or
stepped so that the average slope is not steeper than forty five degrees with no step more than 1.5 m high, provided such slope does not endanger any structure, including subsurface structures. All sides or slopes of excavations or embankments shall be inspected after rainstorms, or any other hazard increasing event, and safe conditions shall be restored. Sheet piling and bracing needed in trench excavations shall have adequate strength to resist possible forces resulting from earth or surcharge pressure. Design of Protection system shall be checked by a qualified Geotechnical Engineer.
**Guard Rail**
A guard rail or a solid enclosure at least 1 m high shall be provided along the open sides of excavations, except that such guard rail or solid enclosure may be omitted from a side or sides when access to the adjoining area is precluded, or where side slopes are one vertical to three horizontal or flatter.
#### 3.12.2.2 Placing of construction material
Excavated materials and superimposed loads such as equipment, trucks, etc. shall not be placed closer to the edge of the excavation than a distance equal to one and onehalf times the depth of such excavation, unless the excavation is in rock or the sides have been sloped or sheet piled (or sheeted) and shored to withstand the lateral force imposed by such superimposed load. When sheet piling is used, it shall extend at least 150 mm above the natural level of the ground. In the case of open excavations with side slopes, the edge of excavation shall be taken as the toe of the slope.
#### 3.12.2.3 Safety regulations
Whenever subsurface operations are conducted that may impose loads or movement on adjoining property, such as driving of piles, compaction of soils, or soil densification, the effects of such operations on adjoining property and structures shall be considered. The owner of the property that may be affected shall be given 48 hours written notice of the intention to perform such operations. Where construction operations will cause changes in the ground water level under adjacent buildings, the effects of such changes on the stability and settlement of the adjacent foundation shall be investigated and provision made to prevent damage to such buildings. When a potential hazard exists, elevations of the adjacent buildings shall be recorded at intervals of twenty four hours or less to ascertain if movement has occurred. If so, necessary remedial action shall be undertaken immediately.
Whenever, an excavation or fill is to be made that will affect safety, stability, or usability of, the adjoining properties or buildings shall be protected as required by the provisions of Sec 3.3 Part 7.
On excavation, the soil material directly underlying footings, piers, and walls shall be inspected by an engineer/architect prior to construction of the footing. If such inspection indicates that the soil conditions do not conform to those assumed for the purposes of design and described on the plans, or are unsatisfactory due to disturbance, then additional excavation, reduction in allowable bearing pressure, or other remedial measures shall be adopted.
Except in cases where a proposed excavation will extend less than 1.5 m below grade, all underpinning operations and the construction and excavation of temporary or permanent cofferdams, caissons, braced excavation surfaces, or other constructions or excavations required for or affecting the support of adjacent properties or buildings shall be subject to controlled inspection. The details of underpinning, and construction of cofferdams, caissons, bracing or other constructions required for the support of adjacent properties or buildings shall be shown on the plans or prepared in the form of shop or detail drawings and shall be approved by the engineer who prepared the plans.
## **3.13 Dewatering**
All excavations shall be drained and the drainage maintained as long as the excavation continues or remains. Where necessary, pumping shall be used. No condition shall be created as a result of construction operations that will interfere with natural surface drainage. Water courses, drainage ditches, etc. shall not be obstructed by refuse, waste building materials, earth, stones, tree stumps, branches, or other debris that may interfere with surface drainage or cause the impoundment of surface water.
## **3.14 Slope Stability of Adjoining Buildings**
The possibility of overturning and sliding of the building shall be considered. The minimum factor of safety against overturning of the structure as a whole shall be 1.5. Stability against overturning shall be provided by the dead load of the building, the allowable uplift capacity of piling, anchors, weight of the soil directly overlying footings provided that such soil cannot be excavated without recourse to major modification of the building, or by any combination of these factors.
The minimum factor of safety against sliding of the structure under lateral load shall be 1.5. Resistance to lateral loads shall be provided by friction between the foundation and the underlying soil, passive earth pressure, batter piles or by plumb piles, subject to the following:
* (i) The resistance to lateral loads due to passive earth pressure shall not be taken into consideration where the abutting soil could be removed inadvertently by excavation.
* (ii) In case of pile supported structures, frictional resistance between the foundation and the underlying soil shall be discounted.
* (iii) The available resistance to friction between the foundation and the underlying soil shall be predicted on an assumed friction factor of 0.5. A greater value of the coefficient of friction may be used subject to verification by analysis and test.
The faces of cut and fill slopes shall be prepared and maintained to control erosion. The control may consist of effective planting. The protection for slopes shall be installed as soon as practicable. Where cut slopes are not subject to erosion due to erosion resistant character of the materials, such protection may be omitted. Where necessary, check dams, cribbing, riprap or other devices or methods shall be employed to control erosion.
## **3.15 Fills**
### **3.15.1 Quality of Fill**
The excavation outside the foundation shall be backfilled with soil that is free of organic material, construction debris and large rocks. The backfill shall be placed in lifts and compacted in a manner which does not damage foundation, the waterproofing or damp-proofing material.
### **3.15.2 Placement of Fill**
Fills to be used to support the foundation of any building or structure shall be placed in accordance with established engineering principle. Before placement of the fill, the existing ground surface shall be stripped off all organic growth, timber, rubbish and debris. After stripping, the ground surface shall be compacted. Materials for fill shall consist of sand, gravel, crushed stone, crushed earth, or a mixture of these. The fill material shall contain no particles exceeding 100 mm in the largest dimension. A soil investigation report and a report of satisfactory placement of fill, both acceptable
to the Building Official shall be submitted. In an uncontrolled fill, the soil within the building area shall be explored using test pits. At least one test pit penetrating at least 2 m below the level of the bottom of the proposed foundation shall be provided for every 200 m2 of building area. Wherever such test pits consistently indicate that the fill is composed of material that is free of voids and free of extensive inclusion of mud, organic materials such as paper, garbage, cans, metallic objects, or debris, the fill material shall be acceptable. Where the fill shows voids or inclusions as described above, either the fill shall be treated as having no presumptive bearing capacity, or the building shall incorporate adequate strength and stiffness to bridge such voids or inclusions or shall be articulated to prevent damage due to differential or localized settlement of the fill.
### **3.15.3 Specifications**
Where foundations are to be placed on controlled fill materials, the fill must be compacted in layers not exceeding 300 mm. Clear specifications shall be provided for the range of water content, the degree of compaction to be achieved and the method of compaction that shall be followed. Such specifications shall be based on the shear strength requirement for the fill soil and allowable settlement estimate. The minimum density of controlled fill shall be 95% of the optimum density obtained from "Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort ", (ASTM D1557).
The degree of compaction achieved in a fill shall be obtained from in-situ density measurements. No new layer shall be placed unless a satisfactory density is attained in each layer.
## **3.16 Protective Retaining Structures for Foundations/ Shore Piles**
A retaining wall is a wall designed to resist lateral earth and/or fluid pressures, including any surcharge, in accordance with accepted engineering practice. Retaining walls for foundations shall be designed to ensure stability against overturning, sliding, excessive foundation pressure and water uplift; and that they be designed for a safety factor of 1.5 against lateral sliding and overturning. Generally sheet pile retaining walls are used for construction raft foundations for buildings. Taller sheet piles may need a tie back anchor driven and anchored behind the soil of the sheet pile retaining wall.
## **3.17 Waterproofing and Damp-Proofing**
### **3.17.1 General**
Walls or portions thereof that retain earth and enclose interior spaces, and floors below grade shall be waterproofed and damp-proofed, with the exception of those spaces where such omission is not detrimental to the building or occupancy. The roof is also required to be waterproofed. The owner shall perform a subsurface investigation to determine the possibility of the ground water table rising above the proposed elevation of the floor or floors below grade unless satisfactory data from adjacent areas demonstrate that ground water has not been a problem.
There may arise two situations: (i) where no hydrostatic pressure occurs and (ii) where hydrostatic pressure occurs. Where hydrostatic pressure conditions exist, floors and walls below finished ground level shall be waterproofed in accordance with Sec 3.17.1.1 below. Where hydrostatic pressure conditions do not exist, dampproofing and perimeter drainage shall be provided in accordance with Sec 3.17.1.2 below. In addition, the damp-proofing and waterproofing shall also meet the requirements of Sec 3.13.3. All damp-proofing and waterproofing materials shall conform to the requirements of Sec 2.16.7 of Part 5.
#### 3.17.1.1 Waterproofing where hydrostatic pressure occurs
Where ground water investigation indicates that a hydrostatic pressure condition exists, or is likely to occur, walls and floors shall be waterproofed in accordance with the provisions stated as under.
#### 3.17.1.2 Floor waterproofing
Floors required to be waterproofed shall be of concrete and shall be designed and constructed to withstand the anticipated hydrostatic pressure. Waterproofing of the floor shall be accomplished by placing under the slab a membrane of rubberized asphalt, or butyl rubber, or polymer modified asphalt, or neoprene, or not less than 0.15 mm polyvinyl chloride or polyethylene, or other approved materials, capable of bridging nonstructural cracks. Joints in the membrane shall be lapped not less than 150 mm and sealed in an approved manner.
#### 3.17.1.3 Wall waterproofing
Walls required to be waterproofed shall be of concrete or masonry designed to withstand the anticipated hydrostatic pressure and other lateral loads. Prior to the application of waterproofing materials on concrete walls, all holes and recesses resulting from the removal of form ties shall be sealed with a bituminous material or other approved methods or materials. Unit masonry walls shall be pargeted on the exterior surface below ground level with not less than 10 mm of Portland cement mortar. The pargeting shall be continued to the foundation. Pargeting of unit masonry walls is not required where a material is approved for direct application to the masonry.
Waterproofing shall be applied from a point 300 mm above the maximum elevation of the ground water table down to the top of the spread portion of the foundation. The remainder of the wall up to a level not less than 150 mm above finished grade shall be damp-proofed **.**
Wall waterproofing materials shall consist of two-ply hot-mopped felts, not less than 0.15 mm polyvinylchloride, 1.0 mm polymer modified asphalt, 0.15 mm polyethylene or other approved methods or materials capable of bridging nonstructural cracks. Joints in the membrane shall be lapped not less than 150 mm and sealed in an approved manner. Joints in walls and floors, joints between the wall and the floor, and penetrations of the wall and floor shall be made watertight utilizing established methods and materials.
#### 3.17.1.4 Damp-proofing with no hydrostatic pressure
Where hydrostatic pressure will not occur, floors and walls shall be damp-proofed and a subsoil drainage system shall be installed as described below:
#### 3.17.1.5 Floor damp-proofing
For floors, damp-proofing materials shall be installed between the floor and base materials. The base material shall not be less than 100 mm in thickness consisting of gravel or crushed stone containing not more than 10 percent material that passes a 4.75 mm sieve. Where a site is located in well drained gravel or sand/gravel mixture, a floor base is not required. When the finished ground level is below the floor level for more than 25 percent of the perimeter of the building, the base material need not be provided. Where a separate floor is provided above a concrete slab the dampproofing may be installed on top of the slab.
Damp-proofing materials, where installed beneath the slab, shall consist of not less than 0.15 mm polyethylene with joints lapped not less than 150 mm, or other approved methods or materials. Where permitted to be installed on top of the slab, damp-proofing shall consist of mopped on bitumen, not less than 0.1 mm polyethylene, or other approved methods or materials. Joints in membranes shall be lapped not less than 150 mm and sealed in an approved manner.
#### 3.17.1.6 Wall damp-proofing
For walls, damp-proofing materials shall be installed and shall extend from a point 150 mm above grade, down to the top of the spread portion of the foundation.
Wall damp-proofing material shall consist of a bituminous material, acrylic modified cement base coating, rubberized asphalt, polymer-modified asphalt, butyl rubber, or other approved materials capable of bridging nonstructural cracks.
#### 3.17.1.7 Perimeter drain
A drain shall be placed around the perimeter of a foundation that consists of gravel or crushed stone containing not more than 10 percent material that passes through a 4.76 mm sieve. The drain shall extend a minimum of 300 mm beyond the outside edge of the foundation. The thickness shall be such that the bottom of the drain is not higher than the bottom of the base under the floor, and that the top of the drain is not less than 150 mm above the top of the foundation. The top of the drain shall be covered with an approved filter membrane material. Where a drain tile or perforated pipe is used, the invert of the pipe or tile shall not be higher than the floor elevation. The top of joints or the top of perforations shall be protected with an approved filter membrane material. The pipe or tile shall be placed on not less than 50 mm of gravel or crushed stone complying with this section, and shall be covered with not less than 150 mm of the same material.
The floor base and foundation perimeter drain shall discharge by gravity or mechanical means into an approved drainage system. Where a site is located in well drained gravel or sand/gravel mixture, a dedicated drainage system is not required. When the finished ground level is below the floor level for more than 25 percent of the perimeter of the building, the foundation drain need be provided only around that portion of the building where the ground level is above the floor level.
### **3.17.2 Other Damp-proofing and Waterproofing Requirements**
#### 3.17.2.1 Placement of backfill
The excavation outside the foundation shall be backfilled with soil that is free of organic material, construction debris and large rocks. The backfill shall be placed in lifts and compacted in a manner which does not damage the waterproofing or dampproofing material or structurally damage the wall.
#### 3.17.2.2 Site grading
The ground immediately adjacent to the foundation shall be sloped away from the building at a slope not less than 1 unit vertical in 12 units horizontal (1:12) for a minimum distance of 2.5 m measured perpendicular to the face of the wall or an alternative method of diverting water away from the foundation shall be used. Consideration shall be given to possible additional settlement of the backfill when establishing the final ground level adjacent to the foundation.
#### 3.17.2.3 Erosion protection
Where water impacts the ground from the edge of the roof, down spout, scupper, valley or other rainwater collection or diversion device, provisions shall be used to prevent soil erosion and direct the water away from the foundation.
## **3.18 Foundation on Slopes**
Where footings are to be founded on a slope, the distance of the sloping surface at the base level of the footing measured from the centre of the footing shall not be less than twice the width of the footing.
When adjacent footings are to be placed at different levels, the distance between the edges of footings shall be such as to prevent undesirable overlapping of structures in soil and disturbance of the soil under the higher footing due to excavation of the lower footing.
On a sloping site, footing shall be on a horizontal bearing and stepped. At all changes of levels, footings shall be lapped for a distance of at least equal to the thickness of foundation or three times the height of step, whichever is greater. Adequate precautions shall be taken to prevent tendency for the upper layers of soil to move downhill.
## **3.19 Foundations on Fills and Problematic Soils**
### **3.19.1 Footings on Filled up Ground**
Footings shall not be constructed on loosely filled up ground with non-uniform density or consistency, unless adequate strengthening of the soil is made by applying ground improvement techniques.
### **3.19.2 Ground Improvement**
In poor and weak subsoil, the design of shallow foundation for structures and equipment may present problems with respect to both sizing of foundation as well as control of foundation settlements. A viable alternative in certain situations developed over recent years is to improve the subsoil to an extent that the subsoil would develop an adequate bearing capacity and foundations constructed after subsoil improvement would have resultant settlements within acceptable limits. Selection of ground improvement techniques may be done in accordance with good practice.
### **3.19.3 Soil Reinforcement**
Use of suitable geo-synthetics/geo-textiles may be made in an approved manner for ground improvement where applicable based on good practice.
## **3.20 Foundation Design for Dynamic Forces**
### **3.20.1 Effect of Dynamic Forces**
Where machinery operations or other vibrations are transmitted through foundation, consideration shall be given in the foundation design to prevent detrimental disturbance of the soil. Impact forces shall be neglected in foundation design except for foundations bearing on loose granular soils, foundations supporting cranes, heavy machinery and moving equipment, or where ratio of live load causing the impact to the dead load exceeds 50%.
### **3.20.2 Machine Foundation**
Machine foundations are subjected to the dynamic forces caused by the machine. These dynamic forces are transmitted to the foundation supporting the machine. Although the moving parts of the machine are generally balanced, there is always some unbalance in practice which causes an eccentricity of rotating parts. This produces an oscillating force. The machine foundation must satisfy the criteria for dynamic loading in addition to that for static loading.
#### 3.20.2.1 Types of machine foundations
Basically, there are three types of machine foundation:
* (i) Machines which produce a periodic unbalanced force, such as reciprocating engines and compressors. The speed of such machines is generally less than 600 rpm. In these machines, the rotary motion of the crank is converted into the translatory motion. The unbalanced force varies sinusoidal.
* (ii) Machines which produce impact loads, such as forge hammers and punch presses. In these machines, the dynamic force attains a peak value in a very short time and then dies out gradually. The response is a pulsating curve. It vanishes before the next pulse. The speed is usually between 60 to 150 blows per minute.
* (iii) High speed machines, such as turbines, and rotary compressors. The speed of such machines is very high; sometimes, it is even more than 3000 rpm.
The following four types of machine foundations are commonly used.
* (i) Block Type: This type of machine foundation consists of a pedestal resting on a footing (Figure 6.3.4a). The foundation has a large mass and a small natural frequency.
* (ii) Box Type: The foundation consists of a hollow concrete block (Figure 6.3.4b). The mass of the foundation is less than that in the block type and the natural frequency is increased.
* (iii) Wall Type: A wall type of foundation consists of a pair of walls having a top slab. The machine rests on the top slab (Fig6.3.4c).
* (iv) Framed Type: This type of foundation consists of vertical columns having a horizontal frame at their tops. The machine is supported on the frame (Figure 6.3.4d).
Machines which produce periodical and impulsive forces at low speeds are generally provided with a block type foundation. Framed type foundations are generally used for the machines working at high speeds and for those of the rotating types. Some machines which induce very little dynamic forces, such as lathes, need not be provided with a machine foundation. Such machines may be directly bolted to the floor.
![Types of machine foundations showing (a) Block type pedestal on footing, (b) Box type hollow concrete block, (c) Wall type pair of walls with top slab, and (d) Framed type vertical columns with horizontal top frame]()
#### 3.20.2.2 Design considerations
For satisfactory performance, machine foundations should satisfy the following requirements: (i) resonance is avoided, (ii) bearing capacity and settlement are safe, and (iii) there is an adequate vibration and shock isolation. Avoidance of resonance is discussed in this Section.
**Resonance:**
Based on their operating frequencies, the machines are classified as (i) low speed having frequency less than 300 revolutions per minute (rpm), (ii) medium speed, frequency 300 to 1000 rpm, and (iii) high speed, frequency greater than 1000 rpm. To avoid resonance, the natural frequency (or the resonant frequency) of the machine foundation-soil system must be either very large or very small compared to the operating speed of the machine.
**Low speed machines ($f_1$ \< 300 rpm):**
Provide a foundation with a natural frequency at least twice the operating frequency, i.e., the frequency ratio $r$ ($= f_1/f_n$) is less than 0.5. Natural frequency can be increased (i) by increasing base area or reducing total static weight of the foundation, (ii) by increasing modulus of shear rigidity of the soil by compaction, grouting or injection, (iii) by using piles to provide the required foundation stiffness.
**High speed machines ($f_1$ > 1000 rpm):**
Provide a foundation with natural frequency not higher than one-half of the operating value, i.e., frequency ratio $\geq 2$. Natural frequency can be decreased by increasing weight of foundation. During starting and stopping, the machine will operate briefly at resonant frequency $f_r$ of the foundation. Probable amplitude is computed at both $f_r$ and $f_1$ and compared with allowable values to determine if the foundation arrangement must be altered.
**Types of foundations:**
Considering their structural forms, the machine foundations, in general, are of the following types: (i) box foundation consisting of a pedestal of concrete, (ii) box foundation consisting of a hollow concrete block, (iii) wall foundation consisting of a pair of walls supporting the machine. (iv) framed foundation consisting of vertical columns and a top horizontal frame work which forms the seat of essential machinery.
Low speed machines (e.g., forge hammers, presses, low speed reciprocating engines and compressors) are generally supported on block foundation having a large contact area with soil.
Medium speed machines (e.g., reciprocating diesel and gas engines) also have, in general, block foundations resting on springs or suitable elastic pads.
High speed and rotating type of machines (e.g., internal combustion engines, electric motors, and turbo generator machines) are generally mounted on framed foundations. Other high speed machines are placed on block foundations.
As far as possible, the centre of gravity of the whole system and the centroid of the base area should be on the same vertical axis. At the most an eccentricity of 5% could be allowed.
**Permissible amplitude:**
Many times the permissible amplitude at operating speed is specified by the manufactures. If not specified, the following values may be adopted for guidance (i) low speed machines. (B1 \< 500 rpm), horizontal and vertical vibrations, A 5 0.25 mm. (ii) operating speed B1 5 500 to 1500 rpm, A 5 0.4 mm to 0.6 mm for horizontal, and A 5 0.7 mm to 0.9 mm for vertical mode of vibration; (iii) operating speed B1 up to 3000 rpm, A 5 0.2 mm for horizontal and A 5 0.5 mm for vertical vibrations (iv) hammer foundations, A 5 10 mm.
#### 3.20.2.3 Design methods
The various design methods can be grouped as follows: (i) empirical and semiempirical methods, (ii) methods considering soil as a spring and (iii) methods considering soil as a semi-infinite elastic mass (elastic half-space-approach) and its equivalent lumped parameter method. The lumped parameter method is currently preferred and will be described here. A good machine foundation should satisfy the following criteria.
* (i) Like ordinary foundations, it should be safe against shear failure caused by superimposed loads, and also the settlements should be within the safe limits.
* (ii) The soil pressure should normally not exceed 80% of the allowable pressure for static loading.
* (iii) There should be no possibility of resonance. The natural frequency of the foundation should be either greater than or smaller than the operating frequency of the machine.
* (iv) The amplitudes under service condition should be within the permissible limits for the machine.
* (v) The combined centre of gravity of the machine and the foundation should be on the vertical line passing through the centre of gravity of the base plane.
* (vi) Machine foundation should be taken to a level lower than the level of the foundation of the, adjacent buildings and should be properly separated.
* (vii) The vibrations induced should neither be annoying to the persons nor detrimental to other structures.
* (viii) Richart (1962) developed a plot for vertical vibrations, which is generally taken as a guide for various limits of frequency and amplitude which has been presented in Figure 6.3.5(a). A modified chart suggested by IS: 2974-Part 1, Figure 6.3.5(b) may also be used.
* (ix) The depth of the ground-water table should be at least one fourth of the width of the foundation below the base place.
#### 3.20.2.4 Vibration analysis of a machine foundation:
Although a machine foundation has 6 degree of freedom, it is assumed to have a single degree of freedom for a simplified analysis. Figure 6.3.6 shows a machine foundation supported on a soil mass. In this case, the mass mf lumps together the mass of the machine and the mass of foundation. The total mass mf acts at the centre of gravity of the system. The mass is under the supporting action of the soil. The elastic action can be lumped together into a single elastic spring with a stiffness k. Likewise; all the resistance to motion is lumped into the damping coefficient c. Thus the machine foundation reduces to a single mass having one degree of freedom. The analysis of damped, forced vibration is, therefore, applicable to the machine foundation.
![Limits of frequency and amplitudes of foundation showing (a) Richart (1962) chart and (b) IS 2974-Part 1 1982 chart]()
![Machine foundation supported on a soil mass showing lumped mass mf, spring stiffness k, and damping coefficient c]()
#### 3.20.2.5 Determination of parameters for vibration analysis
For vibration analysis of a machine foundation, the parameters m, c and k are required. These parameters can be determined as under.
**Mass (m):**
When a machine vibrates, some portion of the supporting soil mass also vibrates. The vibrating soil is known as the participating mass or in-phase soil mass. Therefore, the total mass of the system is equal to the mass of the foundation block and machine $(m_f)$ and the mass $(m_s)$ of the participating soil. Thus
$$
m = m_f + m_s \tag{6.3.51}
$$
Unfortunately, there is no rational method to determine the magnitude of $m_s$. It is usually related to the mass of the soil in the pressure bulb. The value of $m_s$ generally varies between zero and $m_f$. In other words, the total mass $(m)$ varies between $m_f$ and $2m_f$ in most cases.
**Spring Stiffness (k):**
The spring stiffness depends upon the type of soil, embedment of the foundation block, the contact area and the contact pressure distribution. The following are the common methods.
**Laboratory Test:**
A triaxial test with vertical vibrations is conducted to determine Young's modulus $(E)$. Alternatively, the modulus of rigidity $(G)$ is determined conducting the test under torsional vibration, and $E$ is obtained indirectly from the relation, $E = 2G(1 + \mu)$, where µ is Poisson's ratio. The stiffness $(k)$ is determined as
$$
k = \frac{A_{sp}E}{L} \tag{6.3.52}
$$
Where, $A_{sp}$ = cross-sectional area of the specimen, and $L$ = length of the specimen.
Barkan's Method:
The stiffness can also be obtained from the value of $E$ using the following relation given by Barken.
$$
k = \frac{1.13E}{1-\mu}\sqrt{A} \tag{6.3.53}
$$
Where, $A$ = base area of the machine, i.e. area of contact.
Plate Load Test:
A repeated plate load test is conducted and the stiffness of the soil $k_p$ is found as the slope of the load-deformation curve. The spring constant $k$ of the foundation is as under.
For cohesive soils:
$$
k = k_p\left(\frac{B}{B_p}\right) \tag{6.3.54}
$$
For cohesionless soil:
$$
k = k_p\left(\frac{B+0.3}{B_p+0.3}\right)^2 \tag{6.3.55}
$$
Where, $B$ is the width of foundation (in m), $B_p$ is the width of plate (in m). Alternatively, spring constant can be obtained from the subgrade modulus $k_s$, as
$$
k = k_sA \tag{6.3.56}
$$
Where, $A$ = area of foundation.
Resonance Test:
The resonance frequency $f_n$ is obtained using a vibrator of mass m set up on a steel plate supported on the ground. The spring stiffness obtained from the relation
$$
f_n = \frac{\omega_n}{2\pi} = \frac{1}{2\pi}\sqrt{k/m} = 4\pi^2f_nm \tag{6.3.57}
$$
Where, $\omega_n$ is natural circular frequency.
Damping Constant ($c$):
Damping is due to dissipation of vibration energy, which occurs mainly because of the following reasons.
* (i) Internal friction loss due to hysteresis and viscous effects.
* (ii) Radiational loss due to propagation of waves through soil.
The damping factor D for an under-damped system can be determined in the laboratory. Vibration response is plotted and the logarithmic decrement δ is found from the plot, as
$$
\delta = \frac{2\pi D}{\sqrt{1-D^2}} \Rightarrow D = \frac{\delta}{2\pi} \tag{6.3.58}
$$
The damping factor D may also be obtained from the area of hysteresis loop of the load displacement curve, as
$$
D = \frac{\Delta W}{W} \tag{6.3.59}
$$
Where, $W$ = total work done; and $\Delta W$ = work lost hysteresis. The value of $D$ for most soils generally varies between 0.01 and 0.1.
## **3.21 Geo-Hazard Analysis for Buildings**
Geo-hazard analysis of buildings include design considerations for possible landslides, ground subsidence, earthquakes and other seismic events, erosion and scour, construction in toxic and/or contaminated landfills, groundwater contamination etc. A preliminary review of the selected site should be carried out for existence of any of the above mentioned geo-hazard in the area. A detailed analysis may be carried out only if the preliminary review indicates a significant threat for the building which may exist from any of the above mentioned potential geo-hazard at the selected location for the building. See relevant section for details.
## **3.22 List of Related Appendices**
Appendix D Methods of Soil Exploration, Sampling and Groundwater Measurements
Appendix E Recommended Criteria for Identification and Classification of Expansive Soil
* Appendix F Construction of Pile Foundation
Appendix G Other Methods of Estimating Ultimate Axial Capacity of Piles and Drilled Shafts, and Design Charts for Settlement
Appendix H References of Chapter 3 Part 6 (Soils and Foundations).
# Chapter 4: Bamboo Structures
Source: https://docs.sayed.app/bnbc/part-6-structural-design/chapter-4-bamboo-structures
## **4.1 Scope**
This Section relates to the use of bamboo in construction as structural elements, nonstructural elements and also for temporary works in structures or elements of the structure, ensuring quality and effectiveness of design and construction using bamboo. It covers minimum strength data, dimensional and grading requirements, seasoning, preservative treatment, design and jointing techniques with bamboo which would facilitate scientific application and long-term performance of structures. It also covers guidelines so as to ensure proper procurement, storage, precautions and design limitations on bamboo.
## **4.2 Terminology**
For the purpose of this Section, the following definitions shall apply.
### **4.2.1 Anatomical Purpose Definitions**
| BAMBOO | Tall perennial grasses found in tropical and sub-tropical
regions. They belong to the family Poaceae and sub-family
Bambusoidae. |
| ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BAMBOO CULM | A single shoot of bamboo usually hollow except at nodes
which are often swollen. |
| BAMBOO
CLUMP | A cluster of bamboo culms emanating from two or more
rhizomer in the same place. |
| CELLULOSE | A carbohydrate, forming the fundamental material of all
plants and a main source of the mechanical properties of
biological materials. |
| CELL | A fundamental structural unit of plant and animal life,
consisting of cytoplasm and usually enclosing a central
nucleus and being surrounded by a membrane (animal) or a
rigid cell wall (plant). |
| CROSS WALL | A wall at the node closing the whole inside circumference
and completely separating the hollow cavity below from
that above. |
| HEMI CELLULOSE | The polysaccharides consisting of only 150 to 200 sugar
molecules, also much less than the 10000 of cellulose. |
| LIGNIN | A polymer of phenyl propane units, in its simple form
(C6H5CH3CH2CH3). |
| SLIVER | Thin strips of bamboo processed from bamboo culm. |
| TISSUE | Group of cells, which in higher plants consist of (a)
Parenchyma - a soft cell of higher plants as found in stem
pith or fruit pulp, (b) Epidermis - the outermost layer of
cells covering the surface of a plant, when there are several
layers of tissue. |
### **4.2.2 Structural Purpose Definitions**
| BAMBOO MAT
BOARD | A board made of two or more bamboo mats bonded with
an adhesive. |
| ---------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| BEAM | A structural member which supports load primarily by its
internal resistance to bending. |
| BREAKING
STRENGTH | A term loosely applied to a given structural member with
respect to the ultimate load it can sustain under a given set
of conditions. |
| BUNDLE-COLUMN | A column consisting of three or more number of culm
bound as integrated unit with wire or strap type of
fastenings. |
| CENTRE
INTERNODE | A test specimen having its centre between two nodes. |
| CHARACTERISTIC
LOAD | The value of loads which has a 95 percent probability of
not exceeding during the life of the structure. |
| CHARACTERISTIC
STRENGTH | The strength of the material below which not more than
5 percent of the test results are expected to fall. |
| CLEAVABILITY | The ease with which bamboo can be split along the
longitudinal axis. The action of splitting is known as
cleavage. |
| COLUMN | A structural member which supports axial load primarily
by inducing compressive stress along the fibres. |
| COMMON RAFTER | A roof member which supports roof battens and roof
coverings, such as boarding and sheeting. |
| CURVATURE
DELAMINATION | The deviation from the straightness of the culm.
Separation of mats through failure of glue. |
| END DISTANCE | The distance measured parallel to the fibres of the bamboo
from the centre of the fastener to the closest end of the
member. |
| FLATTEN
BAMBOO | Bamboo consisting of culms that have been cut and
unfolded till it is flat. The culm thus is finally spread open,
the diaphragms (cross walls) at nodes removed and
pressed flat. |
| FULL CULM | The naturally available circular section/shape. |
| FUNDAMENTAL
OR ULTIMATE
STRESS | The stress which is determined on a specified type/size of
culms of bamboo, in accordance with standard practice
and does not take into account the effects of naturally
occurring characteristics and other factors. |
| INNER DIAMETER | Diameter of internal cavity of a hollow piece of bamboo. |
| INSIDE
LOCATION | Position in buildings in which bamboo remains
continuously dry or protected from weather. |
| JOINT | A connection between two or more bamboo structural
elements. |
| JOIST | A beam directly supporting floor, ceiling or roof of a
structure. |
| LENGTH OF
INTERNODE | Distance between adjacent nodes. |
| LOADED END OR | The distance measured from the centre of the fastener to |
| COMPRESSION
END DISTANCE | the end towards which the load induced by the fastener
acts. |
| MATCHET | A light cutting and slashing tool in the form of a large
knife. |
| MAT | A woven sheet made using thin slivers. |
| MORTISE AND
TENON | A joint in which the reduced end (tenon) of one member
fits into the corresponding slot (mortise) of the other. |
| NET SECTION | Section obtained by deducting from the gross cross-section
(A), the projected areas of all materials removed by
boring, grooving or other means. |
| NODE | The place in a bamboo culm where branches sprout and a
diaphragm is inside the culm and the walls on both sides
of node are thicker. |
| OUTER
DIAMETER | Diameter of a cross-section of a piece of bamboo
measured from two opposite points on the outer surface. |
| OUTSIDE
LOCATION | Position in building in which bamboos are occasionally
subjected to wetting and drying as in case of open sheds
and outdoor exposed structures, |
| PERMISSIBLE
STRESS | Stress obtained after applying factor of safety to the
ultimate or basic stress. |
| PRINCIPAL
RAFTER | A roof member which supports purlins. |
| PURLINS | A roof member directly supporting roof covering or
common rafter and roof battens. |
| ROOF BATTENS | A roof member directly supporting tiles, corrugated sheets,
slates or other roofing materials. |
| ROOF SKELETON | The skeleton consisting of bamboo truss or rafter over
which solid bamboo purlins are laid and lashed to the
rafter or top chord of a truss by means of galvanized iron
wire, cane, grass, bamboo leaves, etc. |
| SLENDERNESS
RATIO | The ratio of the length of member to the radius of gyration
is known as slenderness ratio of member. (The length of
the member is the equivalent length due to end
conditions). |
| SPLITS | The pieces made from quarters by dividing the quarters
radially and cutting longitudinally. |
| TAPER | The ratio of difference between minimum and maximum
outer diameter to length. |
| UNLOADED END
DISTANCE | The end distance opposite to the loaded end |
| WALL
THICKNESS | Half the difference between outer diameter and inner
diameter of the piece at any cross-section. |
| WET LOCATION | Position in buildings in which the bamboos are almost
continuously damp, wet or in contact with earth or water,
such as piles and bamboo foundations. |
### **4.2.3 Definitions Relating to Defects**
| BAMBOO BORE/GHOON HOLE | The defect caused by bamboo GHOON beetle (Dinoderus spp. Bostychdae), which attacks felled culms. |
| ---------------------- | ---------------------------------------------------------------------------------------------------------------------------------- |
| CROOKEDNESS | A localized deviation from the straightness in a piece of
bamboo. |
| DISCOLORATION | A change from the normal colour of the bamboo which
does not impair the strength of bamboo or bamboo
composite products. |
### **4.2.4 Definitions Relating to Drying Degrades**
| COLLAPSE | The defect occurring on account of excessive shrinkage,
particularly in thick walled immature bamboo. When the
bamboo wall shrinks, the outer layers containing a larger
concentration of strong fibro-vascular bundles set the weaker
interior portion embedded in parenchyma in tension, causing
the latter to develop cracks. The interior crack develops into
a wide split resulting in a depression on the outer surface.
This defect also reduces the structural strength of round
bamboo. |
| --------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| END SPLITTING | A split at the end of a bamboo. This is not so common a
defect as drying occurs both from outer and interior wall
surfaces of bamboo as well as the end at the open ends. |
| SURFACE
CRACKING | Fine surface cracks not detrimental to strength, However, the
cracking which occurs at the nodes reduces the structural
strength. |
| WRINKLED AND
DEFORMED
SURFACE | Deformation in cross-section, during drying, which occurs in
immature round bamboos of most species; in thick walled
pieces, besides this deformation the outer surface becomes
uneven and wrinkled. Very often the interior wall develops a
crack below these wrinkles, running parallel to the axis. |
## **4.3 Symbols**
For the purpose of this Section, the following letter symbols shall have the meaning indicated against each, unless otherwise stated:
* $A$ = Cross-sectional area of bamboo (perpendicular to the direction of the principal fibres and vessels), $= \frac{\pi}{4}(D^2 - d^2)$, mm2
* $D$ = Outer diameter, mm
* $d$ = Inner diameter, mm
* $E$ = Modulus of elasticity in bending, N/mm2
* $f_c$ = Calculated stress in axial compression, N/mm2
* $f_{cp}$ = Permissible stress in compression along the fibres, N/mm2
* $I$ = Moment of inertia $= \frac{\pi}{64}(D^2 - d^2)$, mm4
* $l$ = Unsupported length of column, m or mm
* $M$ = Moisture content, %
* $r$ = Radius of gyration $= \sqrt{I/A}$, mm
* $R'$ = Modulus of rupture, N/mm2
* $W$ = Wall thickness, mm
* $Z$ = Section modulus, mm3
* $\delta$ = Deflection or deformation, mm.
## **4.4 Materials**
### **4.4.1 Species of Bamboo**
In Bangladesh, four species are widely used, hence studied for the mechanical properties as tabulated in Table 6.4.1-6.4.4 for top, bottom and middle positions. Table 6.4.5 further summarize the average mechanical properties of 21 bamboo species.
**Table 6.4.1: Moisture content and specific gravity values of bamboo species**
| **Species** | **Moistu** | **re content**
| **(%)** | | **S**
| **pecific**
| **Gravity**
|
| |
| ---------------------------------------------------------------------------- | ---------- | -------------------- | ------- | ---------------------- | ------------------------------- | ----------------------------------- | ---------------------------------------- | -------------------------------- | --------------------- |
| | **bottom** | **middle** | **top** | **(base**
**Gre** | **d on oven**
**en volum** | **dry w**
**volu**
**es** | **eight an**
**mes)**
**Oven** | **d at diffe**
**dry volu** | **rent**
**mes** |
| | | | | \*\*bottom \*\* | **middle** | **top** | \*\*bottom \*\* | **middle** | **top** |
| Kali (Oxytenanthera
nigrociliata) | 129 | 118 | 104 | 0.48 | 0.49 | 0.51 | 0.66 | 0.69 | 0.74 |
| Mitinga (Bambusa tulda) | 108 | 92 | 86 | 0.54 | 0.58 | 0.61 | 0.75 | 0.79 | 0.83 |
| Bethua (Bambusa
polymorpha) | 104 | 93 | 79 | 0.55 | 0.57 | 0.61 | 0.79 | 0.81 | 0.54 |
| Borak (Bambusa
balcooa) | 100 | 84 | 66 | 0.57 | 0.64 | 0.74 | 0.79 | 0.84 | 0.85 |
| **Table 6.4.2: Shrinkages of wall thickness and diameter of bamboo species** | | | | | | | | | |
| **Species** | **Sh** | **rinkage i** | **n wall** | **thicknes** | **s (%)** | | **Shrinkage** | **in diamete** | **r (%)** |
| ------------------------------------------------------- | ----------- | ------------- | ---------- | ----------------------- | ------------------------------- | ------------------ | ------------- | -------------- | --------- |
| | **From gr** | **een to 12** | **% mc** | **From g**
**dry** | **reen to o**
**conditio** | **ven**
**n** | **From gr** | **een to 12%** | **mc** |
| | **bottom** | **middle** | **top** | \*\*bottom \*\* | \*\*middle \*\* | **top** | **bottom** | **middle** | **top** |
| Kali (Oxytenanthera
nigrociliata) | 9.6 | 8.1 | 5.9 | 13.2 | 10.7 | 8.7 | 4.8 | 3.0 | 2.4 |
| Mitinga (Bambusa tulda) | 11.9 | 7.3 | 4.9 | 14.9 | 9.6 | 7.6 | 3.9 | 3.5 | 2.6 |
| Bethua (Bambusa
polymorpha) | 10.7 | 6.5 | 5.1 | 12.1 | 10.1 | 8.2 | 7.3 | 5.5 | 4.1 |
| Borak (Bambusa balcooa) | 11.1 | 7.6 | 4.8 | 13.7 | 11.1 | 8.4 | 4.2 | 3.4 | 2.5 |
| **Table 6.4.3: Compressive strength of bamboo species** | | | | | | | | | |
| **Species** | **Com** | **pression** | **parallel** | **to the grai** | **n (kg/cm** | **2****)** |
| -------------------------------------------------------------------------------------- | ---------- | ------------ | ------------ | --------------- | ------------ | --------------------- |
| | | **Green** | | | **Air dry** | |
| | **bottom** | **middle** | **top** | **bottom** | **middle** | **top** |
| Kali (Oxytenanthera
nigrociliata) | 257 | 287 | 301 | 346 | 387 | 417 |
| Mitinga (Bambusa tulda) | 403 | 466 | 513 | 529 | 596 | 620 |
| Bethua (Bambusa
polymorpha) | 320 | 361 | 419 | 452 | 512 | 534 |
| Borak (Bambusa balcooa) | 394 | 459 | 506 | 510 | 536 | 573 |
| **Table 6.4.4: Modulus of elasticity and modulus of rupture values of bamboo species** | | | | | | |
| **Species** | **Mo** | **dulus of** | **elasti** | **city (100** | **0 kg/cm****2** | **)** | | **Modulus** | **of rapture (k** | **g/cm****2****)** |
| --------------------------------- | ---------- | --------------- | ------------ | --------------- | --------------------------- | ------------ | --------------- | --------------- | ----------------- | ----------------------------- |
| | | **Green** | | | **Air dry** | | | **Green** | | **Air dry** |
| | **bottom** | \*\*middle \*\* | \*\*top \*\* | \*\*bottom \*\* | \*\*middle \*\* | \*\*top \*\* | \*\*bottom \*\* | \*\*middle \*\* | **top bottom** | **middle top** |
| Kali | 119 | 131 | 169 | 131 | 150 | 224 | 541 | 459 | 415
721 | 580 530 |
| (Oxytenanthera
nigrociliata) | | | | | | | | | | |
| Mitinga
(Bambusa
tulda) | 105 | 138 | 147 | 114 | 140 | 168 | 710 | 595 | 542
883 | 745 671 |
| Bethua | 61 | 65 | 82 | 60 | 70 | 96 | 469 | 426 | 373
566 | 468 414 |
| (Bambusa
polymorpha) | | | | | | | | | | |
| Borak
(Bambusa
balcooa) | 72 | 92 | 103 | 93 | 108 | 127 | 850 | 712 | 624
926 | 787 696 |
### **4.4.2 Grouping**
Sixteen species of bamboo are suitable for structural applications and classified into three groups, namely, Group A, Group B and Group C as given in Table 6.4.6.
The characteristics of these groups are as given in Table 6.4.6.
Species of bamboo other than those listed in the Table 6.4.6 may be used, provided the basic strength characteristics are determined and found more than the limits mentioned therein. However, in the absence of testing facilities and compulsion for use of other species, and for expedient designing, allowable stresses may be arrived at by multiplying density with factors as given in Table 6.4.5.
### **4.4.3 Moisture Content in Bamboo**
With decrease of moisture content (M) the strength of bamboo increases exponentially and bamboo has an intersection point (fibre saturation point) at around 25 percent moisture content depending upon the species. Matured culms shall be seasoned to about 20 percent moisture content before use.
**Table 6.4.5: Physical and Mechanical Properties of Bamboos (in Round Form)**
| | | | | **Properties** | | | |
| -------------------------------------- | ----------------------------------------- | ------------------------------------------------------------- | ----------------------------------------------------------------------------------- | ----------------------------------------------------------------------- | ----------------------------------------- | ------------------------------------------------------------------- | ----------------------------------------------------------------------------------------- |
| | | **In Gr** | **een Condition** | | **In** | **Air Dry Co** | **nditions** |
| **Species** | **Density**
**kg/m****3** | **Modulus of**
**Rupture**
**N/mm****2** | **Modulus of**
**Elasticity 10****3**
**N/mm****2** | **Maximum**
**Compressive**
**strength N/mm****2** | **Density**
**kg/m****3** |
**Modulus**
**of Rupture**
**N/mm****2** |
**Modulus of**
**Elasticity 10****3**
**N/mm****2** |
| *Bambusa auriculata* | 594 | 65.1 | 15.01 | 36.7 | 670 | 89.1 | 21.41 |
| *B. balcooa* | 740 | 64.2 | 7.06 | 38.6 | 850 | 68.3 | 9.12 |
| *B. bambos*
*(Syn.B.atwndinacea)* | 559 | 58.3 | 5.95 | 35.3 | 663 | 80.1 | 8.96 |
| *B. burmanica* | 570 | 59.7 | 11.01 | 39.9 | 672 | 105.0 | 17.81 |
| *B. glancescens*
*(Syn.B.nana)* | 691 | 82.8 | 14.77 | 53.9 | — | — | — |
| *B. nutans* | 603 | 52.9 | 6.62 | 45.6 | 673 | 52.4 | 10.72 |
| *B. pallida* | 731 | 55.2 | 12.90 | 54.0 | — | — | — |
| *B. polymorpha* | 610 | 36.6 | 6.0 | 31.4 | 840 | 40.6 | 5.89 |
| *B. tulda* | 610 | 53.2 | 10.3 | 39.5 | 830 | 65.8 | 11.18 |
| *B. ventricosa* | 626 | 34.1 | 3.38 | 36.1 | — | — | — |
| *B. vulgaris* | 626 | 41.5 | 2.87 | 38.6 | — | — | — |
| *Cephalostachyum*
*pergracile* | 601 | 52.6 | 11.16 | 36.7 | 640 | 71.3 | 19.22 |
| *Dendrocalamus giganteous* | 597 | 17.2 | 0.61 | 35.2 | — | — | — |
| *D. hamiltonii* | 515 | 40.0 | 2.49 | 43.4 | — | — | — |
| *D. longispathus* | 711 | 33.1 | 5.51 | 42.1 | 684 | 47.8 | 6.06 |
| *D. membranacaus* | 551 | 26.3 | 2.44 | 40.5 | 664 | 37.8 | 3.77 |
| *D. strictus* | 631 | 73.4 | 11.98 | 35.9 | 728 | 119.1 | 15.00 |
| *Melocanna baccifera* | 817 | 53.2 | 11.39 | 53.8 | 751 | 57.6 | 12.93 |
| *Oxytenanthera*
*abyssinicia* | 688 | 83.6 | 14.96 | 46.6 | — | — | — |
| *Oxytenanthera nigrociliata* | 510 | 40.70 | 11.7 | 25.2 | 830 | 51.98 | 12.85 |
| *Thyrsostachys oliveri* | 733 | 61.9 | 9.72 | 46.9 | 758 | 90.0 | 12.15 |
#### 4.4.3.1
Air seasoning of split or half-round bamboo does not pose much problem but care has to be taken to prevent fungal discoloration and decay. However, rapid drying in open sun can control decay due to fungal and insect attack. Seasoning in round form presents considerable problem as regards mechanical degrade due to drying defects.
A general observation has been that immature bamboo gets invariably deformed in cross-section during seasoning and thick walled immature bamboo generally collapses. Thick mature bamboo tends to crack on the surface, with the cracks originating at the nodes and at the decayed points. Moderately thick immature and thin and moderately thick mature bamboos season with much less degrade. Bamboo having poor initial condition on account of decay, borer holes, etc. generally suffers more drying degrades.
#### 4.4.3.2
Accelerated air seasoning method gives good results. In this method, the nodal diaphragms (septa) are punctured to enable thorough passage of hot air from one end of the resulting bamboo tube to the other end.
### **4.4.4 Grading of Structural Bamboo**
Grading is sorting out bamboo on the basis of characteristics important for structural utilization as under:
* (a) Diameter and length of culm,
* (b) Taper of culm,
* (c) Straightness of culm,
* (d) Inter nodal length,
* (e) Wall thickness,
* (f) Density and strength, and
* (g) Durability and seasoning.
One of the above characteristics or sometimes combination of 2 or 3 characteristics form the basis of grading. The culms shall be segregated species-wise.
**Table 6.4.6: Safe Working Stresses of Bamboos for Structural Designing****(1)**
| **Species** | **Extreme**
**Fibre Stress**
**in Bending**
**N/mm****2** | **Modulus of**
**Elasticity**
**10****3****N/mm****2** | **Allowable**
**Compressive**
**Stress N/mm****2** |
| --------------------------------------------------------------------- | ----------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------- | ----------------------------------------------------------------------- |
| **GROUP A** | | | |
| Barnbusa glancescens (syn. B. nana) | 20.7 | 3.28 | 15.4 |
| Dendrocalamus strictus | 18.4 | 2.66 | 10.3 |
| Oxytenanthera abyss inicia | 20.9 | 3.31 | 13.3 |
| **GROUP B** | | | |
| Bambusa balcooa | 16.05 | 1.62 | 13.3 |
| B. pallida | 13.8 | 2.87 | 15.4 |
| B. nutans | 13.2 | 1.47 | 13.0 |
| B. tulda | 13.3 | 1.77 | 11.6 |
| B. auriculata | 16.3 | 3.34 | 10.5 |
| B. burmanica | 14.9 | 2.45 | 11.4 |
| Cephalostachyum pergraci\[e | 13.2 | 2.48 | 10.5 |
| Melocanna baccifera (Syn. M. | 13.3 | 2.53 | 15.4 |
| bambusoides) | 15.5 | 2.16 | 13.4 |
| Thyrsotachys oliveri | | | |
| **GROUP C** | | | |
| Bambusa arundinacea (Syn. B. bambos) | 14.6 | 1.32 | 10.1 |
| B. polymorpha | 9.15 | 1.71 | 8.97 |
| B. ventricosa | 8.5 | 0.75 | 10.3 |
| B. vulgaris | 10.4 | 0.64 | 11.0 |
| Dendrocalamus longispathus | 8.3 | 1.22 | 12.0 |
| Oxytenanthera nigrociliata | 10.18 | 2.6 | 7.2 |
| (1) The values given pertain to testing of bamboo in green condition. | | | |
**Table 6.4.7: Limiting Strength Values (in Green Condition)**
| | **Modulus of Rupture (R’)**
**N/mm****2** | **Modulus of Elasticity (E)**
**in Bending 10****3****N/mm****2** |
| -------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------- | -------------------------------------------------------------------------------------------- |
| Group A | *R’>70* | *E>9* |
| Group B | *70≥ R’>50* | *9≥E>6* |
| Group C | *50≥ R’>30* | *6≥E>3* |
| **Table 6.4.8: Allowable Long-Term Stress (N/mm****2** **) Per Unit Density (kg/m****3** **)** | | |
| **Condition** | **Axial**
**Compression**
**(no buckling)** | **Bending** | **Shear** |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ----------------------------------------------------- | ----------- | --------- |
| Green | 0.011 | 0.015 | — |
| Air dry (12%) | 0.013 | 0.020 | 0.003 |
| Note: In the laboratory regime, the density of bamboo is conveniently determined. Having known the density of any species of bamboo, permissible stresses can be worked out using factors indicated above. For example, if green bamboo has a density of 600 kg/m3 , the allowable stress in bending would be 0.015 x 600 = 9 N/mm2 ’. | | | |
#### 4.4.4.1 Diameter and length
##### 4.4.4.1.1 Gradation according to the Mean Outer Diameter
For structural Group A and Group B species, culms shall be segregated in steps of 10 mm of mean outer diameter as follows:
Special Grade $70\text{mm} < \text{Diameter} < 100\text{mm}$
Grade I $50\text{mm} < \text{Diameter} < 70\text{mm}$
Grade II $30\text{mm} < \text{Diameter} < 50\text{mm}$
Grade III $\text{Diameter} < 30\text{mm}$
For structural Group C species culms shall be segregated in steps of 20 mm of mean outer diameter
Grade I $80\text{mm} < \text{Diameter} < 100\text{mm}$
Grade II $60\text{mm} < \text{Diameter} < 80\text{mm}$
Grade III $\text{Diameter} < 60\text{mm}$
##### 4.4.4.1.2
The minimum length of culms shall be preferably 6 m for facilitating close fittings at joints.
### **4.4.5 Taper**
The taper shall not be more than 5.8 mm per metre length (or 0.58 percent) of bamboo in any grade of bamboo.
#### 4.4.5.1 Curvature
The maximum curvature shall not be more than 75 mm in a length of 6 m of any grade of bamboo.
#### 4.4.5.2 Wall thickness
Preferably minimum wall thickness of 8 mm shall be used for load bearing members.
#### 4.4.5.3 Defects and permissible characteristics
##### 4.4.5.3.1
Dead and immature bamboos, bore/GHOON holes, decay, collapse, checks more than 3 mm in depth, shall be avoided.
##### 4.4.5.3.2
Protruded portion of the nodes shall be flushed smooth. Bamboo shall be used after at least six weeks of felling.
##### 4.4.5.3.3
Broken, damaged and discolored bamboo shall be rejected.
##### 4.4.5.3.4
Matured bamboo of at least 4 years of age shall be used.
### **4.4.6 Durability and Treatability**
#### 4.4.6.1 Durability
The natural durability of bamboo is low and varies between 12 months and 36 months depending on the species and climatic conditions. In tropical countries the bio-deterioration is very severe, Bamboos are generally destroyed in about one to two years’ time when used in the open and in contact with ground while a service life of two to five years can be expected from bamboo when used under cover and out of contact with ground. The mechanical strength of bamboo deteriorates rapidly with the onset of fungal decay in the sclerenchymatous fibres. Split bamboo is more rapidly destroyed than round bamboo. For making bamboo durable, suitable treatment shall be given.
#### 4.4.6.2 Treatability
Due to difference in the anatomical structure of bamboo as compared to timber, bamboo behaves entirely differently from wood during treatment with preservative. Bamboos are difficult to treat by normal preservation methods in dry condition and therefore treatment is best carried out in green condition.
#### 4.4.6.3 Boucherie Process
In this process of preservative treatment, water borne preservative is applied to end surface of green bamboo through a suitable chamber and forced through the bamboo by hydrostatic or other pressure.
##### 4.4.6.3.1 Performance of treated bamboo
Trials with treated bamboos have indicated varied durability depending upon the actual location of use. The performance in partially exposed and under covered conditions is better.
##### 4.4.6.3.2
For provisions on safety of bamboo structures against fire, see Part 7.
## **4.5 Permissible Stresses**
### **4.5.1 Factor of Safety**
The safety factor for deriving stresses of bamboo shall be as under:
| Extreme fibre stress in beams | 4 |
| ----------------------------------- | --- |
| Modulus of elasticity | 4.5 |
| Maximum compressive stress parallel | 3.5 |
| to grain/fibres | |
### **4.5.2 Coefficient of Variation**
The coefficient of variation (in percent) shall be as under:
| **Property** | **Mean** | **Range** | **Maximum Expected** |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------- | --------- | -------------------- |
| | | | **Value** |
| Modulus of rupture | 15.9 | 5.7-28.3 | 23.4 |
| Modulus of elasticity | 21.1 | 12.7-31.7 | 27.4 |
| Maximum compressive stress | 14.9 | 7.6-22.8 | 20.0 |
| The maximum expected values of coefficient of variation which are the upper confidence limits under normality assumption such that with 97.5 percent confidence the actual strength of the bamboo culms will be at least 53 percent of the average reported value of modulus of rupture in Table 6.4.5. | | | |
### 4.5.3
Solid bamboos or bamboos whose wall thickness ( *w* ) is comparatively more and bamboos which are generally known as male bamboos having nodes very closer and growing on ridges are often considered good for structural purposes.
### 4.5.4
The safe working stresses for 18 species of bamboos are given in Table 4.5.6
### 4.5.5
For change in duration of load other than continuous (long-term), the permissible stresses given in Table 4.5.6 shall be multiplied by the modification factors given below:
| For imposed or medium term loading | 1.25 |
| ---------------------------------- | ---- |
| For short-term loading | 1.50 |
## **4.6 Design Considerations**
### 4.6.1
All structural members, assemblies or framework in a building shall be capable of sustaining, without exceeding the limits of stress specified, the worst combination of all loadings. A fundamental aspect of design will be to determine the forces to which the structure/structural element might be subjected to, starting from the roof and working down to the soil by transferring the forces through various components and connections. Accepted principles of mechanics for analysis and specified design procedures shall be applied (see Chapter 11 Part 6).
### 4.6.2
Unlike timber, bamboo properties do not relate well to species, being dependent among other factors, on position of the culm, geographic location and age. The practice in timber engineering is to base designs on safe working stresses and the same may be adopted to bamboo with the limitations that practical experience rather than precise calculations generally govern the detailing.
### **4.6.3 Net Section**
It is determined by passing a plane or a series of connected planes transversely through the members. Least net sectional area is used for calculating load carrying capacity of a member.
### **4.6.4 Loads**
The loads shall be in accordance with Chapter 2 Part 6.
### **4.6.5 Structural Forms**
#### 4.6.5.1
Main structural components in bamboo may include roof and floor diaphragms, shear walls, wall panellings, beams, piles, columns, etc. Both from the point of view of capacity and deformation, trusses and framed skeletons are much better applications of bamboo.
#### 4.6.5.2 Schematization of bamboo as a structural material
This shall be based on the principles of engineering mechanics involving the following assumptions and practices:
* (a) The elastic behaviour of bamboo, till failure; (plastic behaviour being considered insignificant);
* (b) Bamboo culms are analysed on mean wall thickness basis as hollow tube structure (not perfectly straight) member on mean diameter basis;
* (c) The structural elements of bamboo shall be appropriately supported near the nodes of culm as and where the structural system demands. The joints in the design shall be located near nodes; and
* (d) Bamboo structures be designed like any other conventional structural elements taking care of details with regards to supports and joints; they shall be considered to generally act as a hinge, unless substantiating data justify a fixed joint.
### **4.6.6 Flexural Members**
#### 4.6.6.1
All flexural members maybe designed using the principles of beam theory.
#### 4.6.6.2
The tendency of bamboo beams to acquire a large deflection under long continuous loadings due to possible plastic flow, if any shall be taken care of. Permanent load may be doubled for calculation of deflection under sustained load (including creep) in case of green bamboo having moisture content exceeding 15 percent.
#### 4.6.6.3
The moment of inertia, I shall be determined as follows:
* (a) The outside diameter and the wall thickness should be measured at both ends, correct up to 1 mm for diameter of culm and 0.1 mm for the wall thickness. (For each cross-section the diameter shall be taken twice, in direction perpendicular to each other and so the wall thickness shall be taken as four times, in the same places as the diameter has been taken twice.)
* (b) With these values the mean diameter and the mean thickness for the middle of the beam shall be calculated and moment of inertia determined.
#### 4.6.6.4
The maximum bending stress shall be calculated and compared with the allowable stress.
#### 4.6.6.5
For shear checks, conventional design procedure in accordance with Chapter 11 Part 6 shall be followed. The basic shear stress values (N/mm2 ) for five species of bamboo in split form in green condition can be assumed as under:
| Bambusa pallida | 9.77 |
| ------------------------- | ---- |
| B. Vulgaris | 9.44 |
| Dedroculumus giganteous | 8.86 |
| D. humiltonii | 7.77 |
| Oxytenanthera abyssinicia | 11.2 |
#### 4.6.6.6
Forces acting on a beam, being loads or reaction forces at supports, shall act in nodes or as near to nodes as by any means possible.
### **4.6.7 Bamboo Column (Predominantly Loaded in Axial Direction)**
#### 4.6.7.1
Columns and struts are essential components sustaining compressive forces in a structure. They transfer load to the supporting media.
#### 4.6.7.2
Design of columns shall be based on one of the following two criteria:
* (a) Full scale buckling tests on the same species, size and other relevant variables.
* (b) Calculations, based on the following:
* (i) The moment of inertia shall be as per Sec 4.6.6.3.
* (ii) For bamboo columns the best available straight bamboo culms shall be selected. Structural bamboo components in compression should be kept under a slenderness ratio of 50.
* (iii) The bending stresses due to initial curvature, eccentricities and induced deflection shall be taken into account, in addition to those due to any lateral load.
#### 4.6.7.3
Buckling calculation shall be according to Euler, with a reduction to 90 percent of moment of inertia, to take into account the effect of the taper, provided the reduced diameter is not less than 0.6 percent.
#### 4.6.7.4
For strength and stability, larger diameter thick walled sections of bamboo with closely spaced nodes shall be used, alternatively, smaller sections may be tied together as a bundle-column.
### **4.6.8 Assemblies, Roof Trusses**
#### 4.6.8.1
A truss is essentially a plane structure which is very stiff in the plane of the members, that is the plane in which it is expected to carry load, but very flexible in every other direction. Roof truss generally consists of a number of triangulated frames, the members of which are fastened at ends and the nature of stresses at joints are either tensile or compressive and designed as pin-ended joints \[see Figure 6.4.1.(a)]. Bamboo trusses may also be formed using bamboo mat board or bamboo mat-veneer composite or plywood gusset \[see Figure 6.4.1(b)].
#### 4.6.8.2
Truss shall be analysed from principles of structural mechanics for the determination of axial forces in members. For the influence of eccentricities, due allowance shall be made in design.
#### 4.6.8.3
The truss height shall exceed 0.15 times the span in case of a triangular truss (pitched roofing) and 0.10 times the span in case of a rectangular (parallel) truss.
#### 4.6.8.4
For members in compression, the effective length for in-plane strength verification shall be taken as the distance between two adjacent points of contraflexure. For fully triangulated trusses, effective length for simple span members without especially rigid end-connection shall be taken as the span length.
#### 4.6.8.5
For strength verification of members in compression and connections, the calculated axial forces should be increased by 10 percent.
#### 4.6.8.6
The spacing of trusses shall be consistent with use of bamboo purlins (2 m to 3 m).
#### 4.6.8.7
The ends in open beams, joists, rafters, purlins shall be suitably plugged. Bamboo roof coverings shall be considered as non-structural in function. The common roof covering shall include bamboo mat board, bamboo mat corrugated sheet, bamboo tiles/strings, plastered bamboo reeds, thatch, corrugated galvanized iron sheeting, plain clay tiles or pan tiles, etc.
## **4.7 Design and Techniques of Joints**
### **4.7.1 Bamboo Joints**
Round, tubular form of bamboo requires an approach different to that used for sawn timber. Susceptibility to crushing at the open ends, splitting tendency, variation in diameter, wall thickness and straightness are some of the associated issues which have to be taken care of while designing and detailing the connections with bamboo.
#### 4.7.1.1 Traditional practices
Such joining methods revolve around lashing or tying by rope or string with or without pegs or dowels. Such joints lack stiffness and have low efficiency.
##### **4.7.1.1.1 Lengthening joints (End Joints)**
(a) Lap Joint
In this case, end of one piece of bamboo is made to lap over that of the other in line and the whole is suitably fastened. It may be full lapping or half lapping. Full section culms are overlapped by at least one internode and tied together in two or three places. Efficiency could be improved by using bamboo or hardwood dowels. In half lapping, culms shall preferably be of similar diameter and cut longitudinally to half depth over at least one internode length and fastened as per full lap joint (Figure 6.4.2).
(b) Butt Joint
Culms of similar diameter are butted end to end, interconnected by means of side plates made of quarter round culm of slightly large diameter bamboo, for two or more internode lengths. Assembly shall be fixed and tied preferably with dowel pins. This joint transfers both compressive and tensile forces equally well (Figure 6.4.3).
(c) Sleeves and Inserts
Short length of bamboo of appropriate diameter may be used either externally or internally to join two culms together (Figure 6.4.4).
(d) Scarf Joint
A scarf joint is formed by cutting a sloping plane 1 in 4 to 6 on opposite sides from the ends of two similar diameter bamboo culms to be joined. They shall be lapped to form a continuous piece and the assembly suitably fastened by means of lashings. Using hooked splays adds to the strength and proper location of joints (Figure 6.4.5).
##### 4.7.1.1.2 Bearing joints
Bearing joints are formed when members which bear against one another or cross each other and transfer the loads at an angle other than parallel to the axis.
(a) Butt Joint
The simplest form consists of a horizontal member supported directly on top of a vertical member. The top of the post may be cut to form a saddle to ensure proper seating of beam for good load transfer. The saddle should be close to a node to reduce risk of splitting (Figure 6.4.6).
(b) Tenon Joint
It is formed by cutting a projection (tenon) in walls of one piece of bamboo and filling it into corresponding holes (mortise) in another and keyed. It is a neat and versatile joint for maximum strength and resistance to separation (Figure 6.4.7).
(c) Cross-Over Joint
It is formed when two or more members cross at right angles and its function is to locate the members and to provide lateral stability. In case of the joint connecting floor beam to post, it maybe load bearing (see Figure 6.4.8). Such joints are also used to transmit angle thrust.
(d) Angled Joint
When two or more members meet or cross other than at right angles, angled joints are formed. For butt joints, the ends of the members may be shaped to fit in as saddle joints. Tenons would help in strengthening such joints (see Figure 6.4.9).
#### 4.7.1.2 Modern practices
Following are some of the modern practices for bamboo jointing (Figure 6.4.10):
* (a) Plywood or solid timber gusset plates maybe used at joint assemblies of web and chord connection in a truss and fixed with bamboo pins or bolts. Hollow cavities of bamboo need to be stuffed with wooden plugs.
* (b) Use of wooden inserts to reinforce the ends of the bamboo before forming the joints. Alternatively steel bands clamps with integral bolt/eye may be fitted around bamboo sections for jointing.
#### 4.7.1.3 Fixing methods and fastening devices
In case of butt joints the tie maybe passed through a pre-drilled hole or around hardwood or bamboo pegs or dowels inserted into prefomed holes to act as horns. Pegs are driven from one side, usually at an angle to increase strength and dowels pass right through the member, usually at right angles.
##### 4.7.1.3.1
Normally 1.60 mm diameter galvanized iron wire may be used for tight lashing.
##### 4.7.1.3.2 Wire Bound Joints
Usually galvanized iron 2.00 mm diameter galvanized iron wire is tightened around the joints by binding the respective pieces together. At least two holes are drilled in each piece and wire is passed through them for good results.
##### 4.7.1.3.3 Pin And Wire Bound Joints
Generally 12 mm diameter bamboo pins are fastened to culms and bound by 2.00 mm diameter galvanized iron wire.
##### 4.7.1.3.4 Fish Plates/Gusset Plated Joints
At least 25 mm thick hardwood splice plate or 12 mm thick structural grade plywood are used. Solid bamboo pins help in fastening the assembly.
##### 4.7.1.3.5 Horned Joints
Two tongues made at one end of culm may be fastened with across member with its mortise grooves to receive horns, the assembly being wire bound.
#### 4.7.1.4
For any complete joint alternative for a given load and geometry, description of all fastening elements, their sizes and location shall be indicated. Data shall be based on full scale tests.
#### 4.7.1.5
Tests on full scale joints or on components shall be carried out in a recognized laboratory.
#### 4.7.1.6
In disaster high wind and seismic areas, good construction practice shall be followed taking care of joints, their damping and possible ductility. Bracings in walls shall be taken care of in bamboo structures.
![Some typical configurations for small and large trusses in bamboo showing pin-ended joint trusses and gusset joint trusses]()
![Lap joints in bamboo showing full-lapped spliced joint, full-lapped spliced joint with dowel, and lapped spliced joint with pegs and battens]()
![Butt joint with side plates in bamboo showing assembly with holes for dowels or pins]()
![Sleeves and inserts for bamboo lengthening joints]()
![Scarf joint in bamboo showing sloping cut and lap length]()
![Butt joints in bamboo showing saddle joint close to the node, square notched ends and tenons, and variations of saddle joints with side plates]()
![Tenon joint in bamboo showing tenon and key joint and integral tenon horned joint]()
![Cross over joints in bamboo showing dowelled and tied joint, pegged and tied joint, and purlin-rafter connections]()
![Angled joints with integral tenons for bamboo frame connections]()
![Gusset plated joint showing bottom chord and rafter web connections with bamboo purlin]()
## **4.8 Storage of Bamboo**
Procurement and storage of bamboo stocks are essential for any project work and shall be done in accordance with Part 7 of this Code.
## **4.9 Related References**
* (1) IS 6874: 1973, “Method of Test for Round Bamboo”, Bureau of Indian Standards, India, 1974.
* (2) IS 9096: 1979, “Code of Practice for Preservation of Bamboo for Structural Purposes”, Bureau of Indian Standards, India, 1974.
* (3) Salehuddin, A. B. M., “Unnoto Poddhotite Bash Shongrokkhon o Babohar”, Bangladesh Agriculture Research Institute, 2004.
# Chapter 5: Concrete Material
Source: https://docs.sayed.app/bnbc/part-6-structural-design/chapter-5-concrete-material
## **5.1 General**
### **5.1.1 Scope**
The provisions of this Chapter shall apply to the design of reinforced and prestressed concrete structures specified in Chapters 6, 8, 9 shall be applicable for normal weight aggregate only unless otherwise specified.
### **5.1.2 Notation**
* $C_c$ = Creep coefficient
* $E_c$ = Modulus of elasticity of concrete
* $E_s$ = Modulus of elasticity of reinforcement
* $E_t$ = Modulus of elasticity of concrete at the age of loading t
* $f_c'$ = Specified compressive strength of concrete
* $f_{cr}'$ = Required average compressive strength of concrete used as the basis for selection of concrete proportions
* $f_y$ = Specified yield strength of reinforcement
* $K$ = Coefficient of shrinkage
* $s$ = Standard deviation
* $W_c$ = Unit weight of concrete
* $\varepsilon_{cc}$ = Creep strain in concrete
* $\varepsilon_{sh}$ = Shrinkage of plain concrete
* $\rho$ = Area of steel relative to that of the concrete.
## **5.2 Constituents Of Concrete**
### **5.2.1 Cement**
#### 5.2.1.1
Cement shall conform to one of the following specifications:
* (a) "Composition, Specification and Conformity Criteria for Common Cements" (BDS EN 197-1:2003)
* (b) "Standard Specification for Portland Cement" ( ASTM C150/C150M)
* (c) "Standard Specification for Blended Hydraulic Cements" (ASTM C595/C595M)
* (d) "Standard Performance Specification for Hydraulic Cement" (ASTM C1157/C1157M)
#### 5.2.1.2
Cement used in the construction shall be the same as that used in the concrete mix design.
### **5.2.2 Aggregates**
#### 5.2.2.1
Concrete aggregates shall conform to the standards “Coarse and Fine Aggregates from Natural Sources for Concrete” (BDS 243: 1963); “Standard Specification for Concrete Aggregates” (ASTM C33/C33M).
#### 5.2.2.2
Maximum nominal size of coarse aggregate shall be the minimum of the following:
* (a) One fifth (1/5) the narrowest dimension between sides of forms,
* (b) One third (1/3) the depth of slabs,
* (c) Three fourth (3/4) the minimum clear spacing between individual reinforcing bars, or bundles of bars, or prestressing tendons or ducts.
The above limitations may be relaxed if, in the judgment of the engineer, workability and methods of consolidation are such that concrete can be placed without honeycomb or voids.
#### 5.2.2.3
Coarse aggregate made from Grade A brick as specified in BDS 208 "Specification for Common Building Clay Bricks" may be used in different types slab and non-structural elements, except in applications where the ambient environmental conditions may impair the performance of concrete made of such aggregates.
### **5.2.3 Water**
#### 5.2.3.1
Water used in mixing concrete shall be clean and free from injurious amounts of oils, acids, alkalis, salts, organic materials, or other substances that may be harmful to concrete or reinforcement.
#### 5.2.3.2
For concrete wherein aluminium members will be embedded, mixing water shall not contain harmful amounts of chloride ion as indicated in Sec 5.5.3.
#### 5.2.3.3
Nonpotable water shall not be used in concrete except the following conditions:
* (a) Selection of concrete proportions shall be based on concrete mixes using water from the same source.
* (b) Nonpotable water is permitted only if specified comparative mortar test cubes made with nonpotable water produce at least 90 percent of the strength achieved with potable water.
### **5.2.4 Admixtures**
#### 5.2.4.1
Prior approval of the engineer shall be required for the use of admixtures in concrete. All admixtures shall conform to the requirements of this Section and Sec 2.4.5 Chapter 2 Part 5.
#### 5.2.4.2
Admixture used in the work shall be the same as that used in the concrete mix design.
#### 5.2.4.3
Admixtures containing chloride other than impurities from admixture ingredients shall not be used in concrete containing embedded aluminium, or in concrete cast against permanent galvanized metal forms (see Sections 5.5.1.2 and 5.5.2.1).
#### 5.2.4.4
Air entraining admixtures, if used in concrete, shall conform to "Specification for Air entraining Admixtures for Concrete" (ASTM C260).
#### 5.2.4.5
Water reducing admixtures, retarding admixtures, accelerating admixtures, water reducing and retarding admixtures, and water reducing and accelerating admixtures, if used in concrete, shall conform to "Standard Specification for Chemical Admixtures for Concrete" (ASTM C494/C494M) or "Standard Specification for Chemical Admixtures for use in Producing Flowing Concrete" (ASTM C1017/C1017M).
#### 5.2.4.6
Fly ash or other pozzolans used as admixtures shall conform to "Standard Specification for Fly Ash and Raw or Calcined Natural Pozzolan for use as a Mineral Admixture in Portland Cement Concrete " (ASTM C618).
#### 5.2.4.7
Ground granulated blast-furnace slag used as an admixture shall conform to "Standard Specification for Ground Iron Blast Furnace Slag for use in Concrete and Mortar" (ASTM C989).
## **5.3 Steel Reinforcement**
### **5.3.1 General**
#### 5.3.1.1
Steel reinforcement for concrete shall conform to the provisions of this Section and those of Sec 2.4.6 Chapter 2 Part 5.
#### 5.3.1.2
Modulus of elasticity $E_s$ for reinforcement shall be taken as 200 kN/mm2 .
#### 5.3.1.3
Reinforcing bars to be welded shall be indicated on the drawings and welding procedure to be used shall be specified. Reinforcing bars otherwise conforming to BDS ISO 6935-2, shall also possess material properties necessary to conform to welding procedures specified in "Structural Welding Code - Reinforcing Steel" (AWS D1.4) of the American Welding Society.
### **5.3.2 Deformed Reinforcement**
#### 5.3.2.1
Deformed reinforcing bars shall conform to one of the following specifications:
* (a) "Bangladesh Standard Steel for the reinforcement of concrete Part-1; Plain bars" (BDS ISO 6935-1 and "Bangladesh Standard Steel for the reinforcement of concrete Part-2; Ribbed bars" (BDS ISO 6935-2)
* (b) "Standard Specification for Deformed and Plain Billet Steel Bars for Concrete Reinforcement" (ASTM A615/A615M),
* (c) "Standard Specification for Rail Steel Deformed and Plain Bars for Concrete Reinforcement" Including Supplementary Requirements S1 (ASTM A996/A996M),
* (d) "Standard Specification for Axle Steel Deformed and Plain Bars for Concrete Reinforcement" (ASTM A996/A996M),
* (e) "Standard Specification for Low Alloy Steel Deformed Bars for Concrete Reinforcement" (ASTM A706/A706M),
* (f) "Specification for Cold Worked Steel Bars for the Reinforcement of Concrete" (BS 4461).
#### 5.3.2.2
Deformed reinforcing bars with a specified yield strength $f_y$ exceeding 420 N/mm2 shall be permitted, provided $f_y$ shall be the stress corresponding to a strain of 0.35 percent and the bars otherwise conform to one of the ASTM specifications listed in Sec 5.3.2.1 (Also see Sec 6.1.2.5).
#### 5.3.2.3
Galvanized reinforcing bars shall comply with "Standard Specification for Zinc Coated (Galvanized) Steel Bars for Concrete Reinforcement" (ASTM A767/ A767M). Epoxy coated reinforcing bars shall comply with "Standard Specifications for Epoxy Coated Reinforcing Steel Bars" (ASTM A775/A775M). Galvanized or epoxy coated reinforcement shall also conform to one of the standards listed in Sec 5.3.2.1 above.
### **5.3.3 Plain Reinforcement**
#### 5.3.3.1
Plain bars shall conform to one of the specifications listed in Section 5.3.2.1 (a), (b), (c) or (d).
#### 5.3.3.2
Plain wire shall conform to "Standard Specification for Steel Wire, Plain, for Concrete Reinforcement" (ASTM A82/A82M) except that for wire with a specified yield strength $f_y$ exceeding 420 N/mm2, $f_y$ shall be the stress corresponding to a strain of 0.0035.
#### 5.3.3.3
Plain bars and wire may be used as ties, stirrups and spirals for all structural members and for all reinforcement in structures up to 4-storey high.
### **5.3.4 Structural Steel, Steel Pipe or Tubing**
#### 5.3.4.1
Structural steel used with reinforcing bars in composite compression members meeting the requirements of Sec 6.3.10.8 or Sec 6.3.10.9 of Chapter 6 of this Part shall conform to one of the following specifications:
* (a) "Standard Specification for Structural Steel" (ASTM A36/A36M),
* (b) "Standard Specification for High Strength Low Alloy Structural Steel"(ASTM A242/A242M),
* (c) "Standard Specification for High Strength Low Alloy Structural Manganese Vanadium Steel" (ASTM A572/A572M),
* (d) "Standard Specification for High Strength Low Alloy ColumbiumVanadium Steels of Structural Quality" (ASTM A572/A572M),
* (e) "Standard Specification of High Strength Low Alloy Structural Steel with 50 ksi (345 Mpa) Minimum Yield Point to 4 in (100 mm) Thick" (ASTM A588/A588M).
#### 5.3.4.2
Steel pipe or tubing for composite compression members composed of a steel encased concrete core meeting the requirements of Sec 6.3.10.7 Chapter 6 of this Part shall conform to one of the following specifications:
* (a) Grade B of "Standard Specification for Pipe, Steel, Black and Hot Dipped, Zinc Coated Welded and Seamless" (ASTM A53/A53M).
* (b) "Standard Specification for Cold Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes" (ASTM A500/A500M).
* (c) "Standard Specification for Hot Formed Welded and Seamless Carbon Steel Structural Tubing" (ASTM A501).
## **5.4 Workability Of Concrete**
Concrete mix proportions shall be such that the concrete is of adequate workability and can properly be compacted. Suggested ranges of values of workability of concrete for some placing conditions, are given in Table 6.5.1.
## **5.5 Durability Of Concrete**
### **5.5.1 Special Exposures**
#### 5.5.1.1
For concrete intended to have low permeability when exposed to water, the water cement ratio shall not exceed 0.50.
#### 5.5.1.2
For corrosion protection of reinforced concrete exposed to brackish water, sea water or spray from these sources, the water cement ratio shall not exceed 0.4.
If minimum concrete cover required by Sec 8.1.8 Chapter 8 of this Part is increased by 12 mm, water cement ratio may be increased to 0.45.
#### 5.5.1.3
The water cement ratio required in Sections 5.5.1.1 and 5.5.1.2 above and Table 6.5.2 shall be calculated using the weight of cement meeting the requirements of BDS EN-197-1 or ASTM C595/C595M or C1157/C1157M, plus the weight of fly ash or pozzolan satisfying ASTM C618 and/or slag satisfying ASTM C989, if any.
### **5.5.2 Sulphate Exposures**
#### 5.5.2.1
Concrete to be exposed to sulphate containing solutions or soils shall conform to the requirements of Table 6.5.2 or be made with a cement that provides sulphate resistance with the maximum water cement ratio provided in Table 6.5.2.
#### 5.5.2.2
Calcium chloride shall not be used as an admixture in concrete exposed to severe or very severe sulphate containing solutions, as defined in Table 6.5.2.
**Table 6.5.1: Suggested Workability of Concrete for Various Placing Conditions**
| **Placing Conditions** | **Degree of**
**Workability** | **Values of Workability** |
| ----------------------------------------------------------------- | ---------------------------------- | --------------------------------------------------------------------------------- |
| Concreting of thin sections with
vibration | Very low | 20-10 seconds Vee-Bee time, or
0.75-0.80 compacting factor |
| Concreting of lightly reinforced
sections with vibration | Low | 10-5 seconds Vee-Bee time, or
0.80-0.85 compacting factor |
| Concreting of lightly reinforced | Medium | 5-2 seconds Vee-Bee time, or 0.85- |
| sections without vibration or | | 0.92 compacting factor, or 25-75 |
| heavily reinforced section with
vibration | | mm slump for 20 mm aggregate\* |
| Concreting of heavily rein-forced
sections without vibration | High | Above 0.92 compacting factor, or
75-125 mm slump for 20 mm
aggregate\* |
* Slump test shall be performed as per ASTM C143. For smaller aggregates the values will be lower.
**Table 6.5.2: Requirements for Normal Weight Aggregate Concrete Exposed to Sulphate Containing Solutions**
| **Sulphate**
**Exposure** | **Water Soluble**
**Sulphate (SO4)**
**in Soil, percent**
**by Weight** | **Sulphate (SO4)**
**in Water, (ppm)** | **Cement Type****1** | **Maximum**
**Water Cement**
**Ratio, by**
**Weight** |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------- | ------------------------------------------- | -------------------------------- | -------------------------------------------------------------------- |
| Negligible | 0.00-0.10 | 0 – 150 | - | - |
| Moderate2 | 0.10-0.20 | 150 -1500 | Other than CEM I and
B type | 0.50 |
| Severe | 0.20-2.00 | 1500 -10,000 | Other than CEM-I and
B type | 0.45 |
| Very
severe | Over 2.00 | Over 10,000 | Other than CEM-I and
B type | 0.45 |
| Notes: Pozzolan that has been determined by test or service record to improve sulphate resistance when used in concrete containing Type V cement. 1 For types of cement see BDS EN 197-1:2003 or ASTM C150 and C595 2 Sea water | | | | |
**Table 6.5.3: Maximum Chloride-ion Content for Corrosion Protection**
| **Type of Member** | **Maximum Water Soluble Chloride Ion (Cl****-****)**
**in Concrete, Percent by Weight of Cement** |
| ------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- |
| Prestressed concrete | 0.06 |
| Reinforced concrete exposed to
chloride in service | 0.15 |
| Reinforced concrete that will be dry or
protected from moisture in service | 1.00 |
| Other reinforced concrete construction | 0.30 |
### **5.5.3 Corrosion of Reinforcement**
#### 5.5.3.1
For corrosion protection, maximum water soluble chloride ion concentrations in hardened concrete at ages from 28 to 42 days contributed from the ingredients including water, aggregates, cementitious materials, and admixtures, shall not exceed the limits of Table 6.5.3. When testing is performed to determine water soluble chloride ion content, test procedure shall conform to AASHTO T260, "Methods of Sampling and Testing for Total Chloride Ion in Concrete and Concrete Raw Materials".
#### 5.5.3.2
When reinforced concrete will be exposed to brackish water, sea water, or spray from these sources, requirements of Sections 5.5.1.1 and 5.5.1.2 for water cement ratio, or concrete strength and minimum cover requirements of Sec 8.1.8 Chapter 8 of this Part shall be satisfied.
### **5.5.4 Minimum Concrete Strength**
Minimum concrete strength for structural use of reinforced concrete shall be 20 N/mm2 . However, for buildings up to 4 storey, the minimum concrete strength may be relaxed to 17 N/mm2 .
## **5.6 Concrete Mix Proportion**
### **5.6.1 General**
#### 5.6.1.1
Proportions of materials for concrete shall be such that :
* (a) Workability and consistency are achieved for proper placement into forms and around reinforcement, without segregation or excessive bleeding;
* (b) Resistance to special exposures to meet the durability requirements of Sec 5.5 are provided; and
* (c) Conformance with strength test requirements of Sec 5.12 is ensured.
#### 5.6.1.2
Where different materials are to be used for different portions of the proposed work, each combination shall be evaluated.
#### 5.6.1.3
Concrete proportions, including water cement ratio, shall be established on the basis of field experience and/or trial mixtures with materials to be employed (Sec 5.6.2) except as permitted in Sec 5.6.3 or required by Sec 5.5.
### **5.6.2 Proportioning Concrete Mix on the Basis of Field Experience and/or Trial Mixtures**
#### 5.6.2.1 Standard deviation
* (a) A standard deviation shall be established where test records are available in a concrete production facility. Test records from which a standard deviation is calculated shall meet the following requirements :
* (i) These shall represent materials, quality control procedures, and conditions similar to those expected for the proposed work. Deviations in materials and proportions for the proposed work shall be more restricted than those within the test records.
* (ii) Test records shall represent concrete produced to meet a specified strength $f_c'$ within 7 N/mm2 of that specified for the proposed work.
* (iii) The record shall consist of at least 30 consecutive tests or two groups of consecutive tests totaling at least 30 tests as defined in Sec 5.12.2.4 except as provided in (b) below.
* (b) Where a concrete production facility does not have test records meeting the requirements of (a) above but does have a record based on 15 to 29 consecutive tests, a standard deviation shall be established as the product of the calculated standard deviation and the modification factor specified in Table 6.5.4. However, the test records shall meet the requirements (i) and (ii) of (a) above and represent only a single record of consecutive tests that span a period of not less than 45 calendar days.
**Table 6.5.4: Modification Factor for Standard Deviation when Less Than 30 Tests are Available**
| **No. of Tests**\* | **Modification Factor for Standard Deviation**\*\* |
| ------------------ | -------------------------------------------------- |
| Less than 15 | See Section 5.6.2.2(b) |
| 15 | 1.16 |
| 20 | 1.08 |
| 25 | 1.03 |
| 30 or more | 1.00 |
* Interpolate for intermediate numbers of tests
* \*\* Modified standard deviation to be used to determine the required average strength *f cr* ' from Sec 5.6.2.2(a).
#### 5.6.2.2 Required average strength
* (a) Required average compressive strength $f_c'$ used as the basis for selection of concrete proportions shall be the larger of the values given by Eq (6.5.1) and (6.5.2) using a standard deviation calculated in accordance with Sec 5.6.2.1(a) or Sec 5.6.2.1(b) above.
* (b) When a concrete production facility does not have field strength test records for calculation of standard deviation meeting the requirements of Sec 5.6.2.1(a) or Sec 5.6.2.1(b), the required average strength shall be determined from Table 6.5.5 and documentation of the average strength shall be in accordance with the requirements of Sec 5.6.2.3 below.
**Table 6.5.5: Required Average Compressive Strength when Data are not available to establish a Standard Deviation**
| **Specified Compressive Strength**
***c***
***f*** '
**N/mm****2** | **Required Average Compressive Strength,**
**′**
**N/mm****2** |
| -------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------- |
| Less than 20 |
′+ 7.0 |
| 20 to 35 |
′+ 8.5 |
| Over 35 |
′+ 10.0 |
#### 5.6.2.3 Documentation of average strength
Documentation shall be prepared to demonstrate that the proposed concrete proportions will produce an average compressive strength equal to or greater than the required average compressive strength (Sec 5.6.2.2). Such documentation shall consist of one or more field strength test records or trial mixtures.
* (a) When test records are used to demonstrate that proposed concrete proportions will produce the required average strength $f_c'$ (Sec 5.6.2.2) such records shall represent materials and conditions similar to those expected. Deviations in materials, conditions and proportions within the test records shall not have been more restricted than those for proposed work. For the purpose of documenting average strength potential, test records consisting of less than 30 but not less than 10 consecutive tests are acceptable provided the test records encompass a period of time not less than 45 days. Required concrete proportions shall be permitted to be established by interpolation between the strengths and proportions of two or more test records each of which meets other requirements of this Section.
* (b) When an acceptable record of field test results is not available, concrete proportions may be established based on trial mixtures meeting the following restrictions :
* (i) Combination of materials shall be those for the proposed work.
* (ii) Trial mixtures having proportions and consistencies required for the proposed work shall be made using at least three different water cement ratios or cement contents that will produce a range of strengths encompassing the required average strength.
* (iii) Trial mixtures shall be designed to produce a slump within ±20 mm of the maximum permitted, and for air entrained concrete the air content shall be within ±0.5 percent of the maximum allowable.
* (iv) For each water cement ratio or cement content, at least three test cylinders for each test age shall be made and cured in accordance with "Method of Making and Curing Concrete Test Specimens in the Laboratory" (ASTM C192/C192M). Cylinders shall be tested at 28 days or at test age designated for the determination of $f_c'$ .
* (v) From the results of cylinder tests, a curve shall be plotted showing the relationship between the water cement ratio or cement content and the compressive strength at designated test age.
* (vi) Maximum water cement ratio or minimum cement content for concrete to be used in the proposed work shall be that shown by the above curve to produce the average strength required by Sec 5.6.2.2 unless a lower water cement ratio or higher strength is required by Sec 5.5.
### **5.6.3 Proportioning by Water Cement Ratio**
#### 5.6.3.1
If the data required in Sec 5.6.2 are not available, concrete proportions shall be based on water cement ratio limits specified in Table 6.5.6 when approved by the engineer.
#### 5.6.3.2
Table 6.5.6 shall be used for concrete to be made with cements meeting strength requirements of “Bangladesh Standard Cement Part-1: Composition, specifications and conformity criteria for common cements” (BDS EN 197-1: 2003), and shall not be applied to concrete containing lightweight aggregates or admixtures other than those for entraining air.
#### 5.6.3.3
Concrete proportioned by water cement ratio limits prescribed in Table 6.5.6 shall also conform to special exposure requirements of Sec 5.5 and to compressive strength test criteria of Sec 5.12.
### **5.6.4 Average Strength Reduction**
As data become available during construction, amount by which value of $f_c'$ must exceed specified value of $f_c'$ may be reduced, provided:
* (a) 30 or more test results are available and the average of test results exceeds that required by Sec 5.6.2.2(a) using a standard deviation calculated in accordance with Sec 5.6.2.1(a), or
* (b) 15 to 29 test results are available and the average of test results exceeds that required by Sec 5.6.2.2(a) using a standard deviation calculated in accordance with Sec 5.6.2.1(b), and provided further that special exposure requirements of Sec 5.5 are met.
**Table 6.5.6: Maximum Permissible Water Cement Ratios for Concrete when Strength Data from Field Experience or Trail Mixers are not Available**
| **Specified Compressive** | **Absolute Water Cement** | **Ratio by Weight** |
| -------------------------- | ---------------------------- | ------------------- |
| **Strength*,**
**′*\* | **Concrete other than air-** | **Air-entrained** |
| **N/mm****2** | **entrained** | **concrete** |
| 17 | 0.66 | 0.54 |
| 20 | 0.60 | 0.49 |
| 25 | 0.50 | 0.39 |
| 30 | 0.40 | \*\* |
| 35 | \*\* | \*\* |
* 28 day strength. With most materials, water cement ratios shown will provide average strengths greater than that required in Sec 5.6.2.2.
* \*\* For strengths above 30 N/mm2 (25 N/mm2 for air entrained concrete) concrete proportions shall be established by methods of Sec 5.6.2.
## **5.7 Preparation of Equipment and Place of Deposit**
Preparation before concrete placement shall include the following:
* (a) All equipment for mixing and transporting concrete shall be clean.
* (b) All debris shall be removed from spaces to be occupied by concrete.
* (c) Forms shall be properly cleaned and coated.
* (d) Masonry filler units that will be in contact with concrete shall be soaked thoroughly.
* (e) Reinforcement shall be thoroughly clean of deleterious coatings.
* (f) Water shall be removed from place of deposit before concrete is placed unless a tremie is used or unless otherwise permitted by the engineer.
* (g) All laitance and other unsound material shall be removed before additional concrete is placed against hardened concrete.
## **5.8 Mixing**
### 5.8.1
All concrete shall be mixed thoroughly until there is a uniform distribution of materials and shall be discharged completely before the mixer is recharged.
### 5.8.2
Ready mixed concrete shall be mixed and delivered in accordance with the requirements of "Standard Specification for Ready Mixed Concrete" (ASTM C94) or "Standard Specification for Concrete Made by Volumetric Batching and Continuous Mixing" (ASTM C685).
### 5.8.3
Job mixed concrete shall be mixed in accordance with the following:
* (a) Mixing shall be done in a batch mixer of approved type.
* (b) Mixer shall be rotated at a speed recommended by the manufacturer.
* (c) Mixing shall be continued for at least 90 seconds after all materials are in the drum, unless a shorter time is shown to be satisfactory by the mixing uniformity tests of "Specification for Ready Mixed Concrete" (ASTM C94).
* (d) Materials handling, batching, and mixing shall conform to the applicable provisions of "Specification for Ready Mixed Concrete" (ASTM C94).
* (e) A detailed record shall be kept to identify:
* (i) number of batches produced;
* (ii) proportions of materials used;
* (iii) approximate location of final deposit in structure;
* (iv) time and date of mixing and placing.
## **5.9 Conveying**
### 5.9.1
Concrete shall be conveyed from the mixer to the place of final deposit by methods that will prevent segregation or loss of materials.
### 5.9.2
Conveying equipment shall be capable of providing a supply of concrete to the place of deposit without segregation of ingredients and without interruptions sufficient to permit loss of plasticity between successive increments.
## **5.10 Depositing**
### 5.10.1
Concrete shall be deposited as near its final position as practical to avoid segregation due to rehandling or flowing.
### 5.10.2
Concreting shall be carried on at such a rate that concrete is at all times plastic and flows readily into spaces between and around the reinforcement.
### 5.10.3
Concrete that has partially hardened or been contaminated by foreign materials shall not be deposited in the structure.
### 5.10.4
Retempered concrete or concrete that has been remixed after initial set shall not be used.
### 5.10.5
After concreting is started, it shall be carried on as a continuous operation until placing of a panel or section, as defined by its boundaries or predetermined joints, is completed except as permitted or prohibited by Sec 5.16.4.
### 5.10.6
Top surfaces of vertically formed lifts shall be generally level.
### 5.10.7
When construction joints are required, joints shall be made in accordance with Sec 5.16.4.
### 5.10.8
All concrete shall be thoroughly consolidated by suitable means during placement and shall be thoroughly worked around reinforcement and embedded fixtures and into corners of forms.
## **5.11 Curing**
### 5.11.1
Concrete (other than high early strength) shall be maintained above 10o C and in a moist condition for at least the first 7 days after placement, except when cured in accordance with Sec 5.11.3.
### 5.11.2
High early strength concrete shall be maintained above 10o C and in a moist condition for at least the first 3 days, except when cured in accordance with Sec 5.11.3.
### **5.11.3 Accelerated Curing**
#### 5.11.3.1
Curing by high pressure steam, steam at atmospheric pressure, heat and moisture or other accepted processes, shall be permitted to accelerate strength gain and reduce time of curing.
#### 5.11.3.2
Accelerated curing shall provide a compressive strength of the concrete at the load stage considered, at least equal to the required design strength at that load stage.
#### 5.11.3.3
Curing process shall be such as to produce concrete with a durability at least equivalent to that obtained for concrete cured by the method of Sec 5.11.1 or 5.11.2.
### 5.11.4
When required by the engineer, supplementary strength tests in accordance with Sec 5.12.4 shall be performed to assure that curing is satisfactory.
## **5.12 Evaluation and Acceptance of Concrete**
### **5.12.1 General**
#### 5.12.1.1
Concrete shall be proportioned to provide an average compressive strength as prescribed in Sec 5.6.2.2 as well as to satisfy the durability criteria of Sec 5.5. Concrete shall be produced to limit frequency of strengths below $f_c'$ to that prescribed in Sec 5.12.3.3.
#### 5.12.1.2
Requirements of shall be based on tests of cylinders made and tested as prescribed in Sec 5.12.3.
#### 5.12.1.3
Unless otherwise specified, $f_c'$ shall be based on 28 day tests. Test age for $f_c'$ shall be indicated in design drawings or specifications, if it is different from 28 days.
#### 5.12.1.4
Splitting tensile strength tests shall not be used as a basis for field acceptance of concrete.
### **5.12.2 Frequency of Testing**
#### 5.12.2.1
Samples for strength tests of each class of concrete placed each day shall be taken not less than once a day, nor less than once for each 60 m3 of concrete, nor less than once for each 250 m2 surface area for slabs or walls.
#### 5.12.2.2
On a given project, if the total volume of concrete is such that frequency of testing required by Sec 5.12.2.1 above would provide less than three strength tests for a given class of concrete, tests shall be made from at least three randomly selected batches or from each batch if three or fewer batches are used.
#### 5.12.2.3
When the total quantity of a given class of concrete is less than 20 m3 , strength tests are not required when evidence of satisfactory strength is submitted to and approved by the Engineer.
#### 5.12.2.4
A strength test shall be the average of the strengths of at least two 150 mm by 300 mm cylinders or at least three 100 mm by 200 mm cylinders made from the same sample of concrete and tested at 28 days or at test age designated for determination of $f_c'$ .
### **5.12.3 Laboratory Cured Specimens**
#### 5.12.3.1
Samples for strength tests shall be taken in accordance with "Method of Sampling Freshly Mixed Concrete" (ASTM C172).
#### 5.12.3.2
Cylinders for strength tests shall be moulded and laboratory cured in accordance with "Practice for Making and Curing Concrete Test Specimens in the Field" (ASTM C31/C31M) and tested in accordance with "Test Method for Compressive Strength of Cylindrical Concrete Specimens" (ASTM C39/C39M).
#### 5.12.3.3
Strength level of an individual class of concrete shall be considered satisfactory if both of the following requirements are met :
* (a) Average of three consecutive strength tests (see Sec 5.12.2.4) equals or exceeds $f_c'$
* (b) No individual strength test (average of two cylinders of 150 mm by 300 mm or average of three cylinders of 100 mm by 200 mm) falls below by more than 3.5 N/mm2 .
#### 5.12.3.4
If either of the requirements of Sec 5.12.3.3 are not met, steps shall be taken to increase the average of the subsequent strength test results. Requirements of Sec 5.12.5 shall be satisfied if the requirement of Sec 5.12.3.3(b) is not met.
### **5.12.4 Field Cured Specimens**
#### 5.12.4.1
The engineer may require strength tests of cylinders cured under field conditions to check adequacy of curing and protection of concrete in the structure.
#### 5.12.4.2
Field cured cylinders shall be cured under field conditions in accordance with "Practice for Making and Curing Concrete Test Specimens in the Field" (ASTM C31/C31M).
#### 5.12.4.3
Field cured test cylinders shall be moulded at the same time and from the same samples as laboratory cured test cylinders.
#### 5.12.4.4
Procedures for protecting and curing concrete shall be improved when the strength of field cured cylinders at the test age designated for determination of $f_c'$ is less than 85 percent of that of companion laboratory cured cylinders. The 85 percent limitation shall not apply if field cured strength exceeds $f_c'$ by more than 3.5 N/mm2 .
### **5.12.5 Investigation of Low Strength Test Results**
#### 5.12.5.1
If the result of any strength test (Sec 5.12.2.4) of laboratory cured cylinders falls below the specified value of by more than 3.5 N/mm2 (Sec 5.12.3.3(b)) or if tests of field cured cylinders indicate deficiencies in protection and curing (Sec 5.12.4.4), steps shall be taken to assure that the load carrying capacity of the structure is not jeopardized.
#### 5.12.5.2
If the likelihood of low strength concrete is confirmed and computations indicate that load carrying capacity may have been significantly reduced, tests of cores drilled from the area in question may be required in accordance with "Method of Obtaining and Testing Drilled Cores and Sawed Beams of Concrete" (ASTM C42/C42M). In such cases, three cores shall be taken for each strength test more than 3.5 N/mm2 below the specified value of $f_c'$ .
#### 5.12.5.3
If concrete in the structure is expected to be dry under service conditions, cores shall be air dried for 7 days before test and shall be tested dry. If concrete in the structure is expected to be more than superficially wet under service conditions, cores shall be immersed in water for at least 40 hours and be tested wet.
#### 5.12.5.4
Concrete in an area represented by core tests shall be considered structurally adequate if the average of three cores is equal to at least 85 percent of $f_c'$ and if no single core is less than 75 percent of $f_c'$ . Additional testing of cores extracted from locations represented by erratic core strength results shall be permitted.
#### 5.12.5.5
If the criteria of Sec 5.12.5.4 above are not met, and if structural adequacy remains in doubt, the responsible authority may order load tests for the questionable portion of the structure, or take other appropriate action.
## **5.13 Properties of Concrete**
### **5.13.1 Strength**
Strength of concrete shall be based on $f_c'$ determined in accordance with the provisions of Sec 5.12.1.
### **5.13.2 Modulus of Elasticity**
#### 5.13.2.1
Modulus of elasticity $E_c$ for stone aggregate concrete may be taken as $44w_c^{1.5}\sqrt{f_c'}$ (N/mm2 ) for values of $w_c$ between 15 and 25 kN/m3 and $f_c'$ in N/mm2 . For normal density concrete, $E_c$ may be taken as $4700\sqrt{f_c'}$.
#### 5.13.2.2
Modulus of elasticity $E_c$ for brick aggregate concrete may be taken as $3750\sqrt{f_c'}$.
### **5.13.3 Creep**
The final (30 year) creep strain in concrete $\varepsilon_{cc}$ shall be predicted from
$$
\varepsilon_{cc} = \frac{stress}{E_t}c_c \tag{6.5.3}
$$
Where,
$E_t$ is the modulus of elasticity of the concrete at the age of loading $t$,
$c_c$ is the creep coefficient.
The creep coefficient may be estimated from Figure 6.5.1. In this Figure, for uniform sections, the effective section thickness is defined as twice the cross-sectional area divided by the exposed perimeter. If drying is prevented by immersion in water or by sealing, the effective section thickness shall be taken as 600 mm.
It can be assumed that about 40%, 60% and 80% of the final creep develops during the first month, 6 months and 30 months under load respectively, when concrete is exposed to conditions of constant relative humidity.
### **5.13.4 Shrinkage**
An estimate of the drying shrinkage of plain concrete may be obtained from Figure 6.5.2. Recommendations for effective section thickness and relative humidity are given in Sec 5.13.3.
Figure 6.5.2 relates to concrete of normal workability made without water reducing admixtures; such concretes shall have an original water content of about 190 litre/m3 . Where concrete is known to have a different water content, shrinkage shall be regarded as proportional to water content within the range 150 to 230 litre /m3 .
The shrinkage of plain concrete is primarily dependent on the relative humidity of the air surrounding the concrete, the surface area from which moisture can be lost relative to the volume of concrete and on the mix proportion. It is increased slightly by carbonation and self-desiccation and reduced by prolonged curing. An estimate of the shrinkage of symmetrically reinforced concrete sections may be obtained from:
Where,
* *ℎ* is the shrinkage of the plain concrete;
* is the area of steel relative to that of the concrete;
* \*+ is a coefficient, taken as 25 for internal exposure and as 15 for external exposure.
![Nomogram and curves showing the effects of relative humidity, age of loading, and effective section thickness upon creep factor]()
### **5.13.5 Thermal Strains**
Thermal strains shall be calculated from the product of a suitable coefficient of thermal expansion and a temperature change. The temperature change can be determined from the expected service conditions and climatic data. Externally exposed concrete does not respond immediately to air temperature change, and climatic temperature ranges may require adjustment before use in movement calculations.
The coefficient of thermal expansion of concrete is dependent mainly on the expansion coefficients for the aggregate and the cement paste, and the degree of saturation of the concrete. The thermal expansion of aggregate is related to mineralogical composition (See Table 6.5.7)
Cement paste has a coefficient of thermal expansion that is a function of moisture content, and this affects the concrete expansion as shown in Fig 6.5.3. It may be seen that partially dry concrete has a coefficient of thermal expansion that is approximately 2 × 10-6 /o C greater than the coefficient for saturated concrete.
## **5.14 Concreting in Adverse Weather**
### 5.14.1
Concreting shall be avoided during periods of near freezing weather.
### 5.14.2
During hot weather, proper attention shall be given to ingredients, production methods, handling, placing, protection, and curing to prevent excessive concrete temperatures or water evaporation that could impair required strength or serviceability of the member or structure.
### 5.14.3
During rainy weather, proper protection shall be given to ingredients, production methods, handling and placing of concrete. If required in the opinion of the engineer, the concreting operation shall be postponed and newly placed concrete shall be protected from rain after forming proper construction joint for future continuation.
![Chart and nomogram showing drying shrinkage of normal-weight concrete with respect to relative humidity, effective section thickness, and water content]()
**Table 6.5.7: Thermal Expansion of Rock Group and Related Concrete**
| Aggregate Type | Typical Coefficient of Expansion (1 × 10-6/oC) |
| ---------------- | -------------------------------------------------------------------- |
| | **Aggregate**
**Concrete** |
| Flint, quartzite | 11
12 |
| Granite, basalt | 7
10 |
| Limestone | 6
8 |
![Curves showing the effect of moisture content and degree of dryness upon the coefficient of thermal expansion of hardened cement and concrete]()
## **5.15 Surface Finish**
### **5.15.1 Type of Finish**
A wide variety of finishes can be produced. Surface cast against forms may be left as cast, e.g. plain or profiled, the initial surface may be removed, e.g. by tooling or sandblasting, or the concrete may be covered, e.g. by paint or tiles; combinations of these techniques may also be adopted, e.g. a ribbed profile with bush hammered ribs. Upper surfaces not cast against forms may be trowelled smooth or profiled, e.g. by tamping; the initial surface may be removed, e.g. by spraying, or it may be covered, e.g. by a screed or plastic floor finish. When selecting the type of finish, consideration shall be given to the ease of producing a finish of the required
standard, the viewing distance and the change of appearance with time. In the case of external surfaces, account shall be taken of the weather pattern at the particular location, any impurities in the air and the effect of the shape of the structure upon the flow of water across its surface. Such considerations will often preclude the specification of surfaces of uniform colour as these are very difficult to produce and deteriorate with time, particularly if exposed to the weather.
### **5.15.2 Quality of Finish**
A high quality finish is one that is visually pleasing; it may include colour variations and physical discontinuities but these are likely to be distributed systematically or randomly over the whole surface rather than being concentrated in particular areas. When deciding on the quality of finish to be specified, consideration should be given to the viewing distance and the exposure conditions.
There is no method whereby the quality of finish that will be accepted can unequivocally be defined. To achieve the quality required calls for good communication between experienced personnel conversant with the production of finishes and close collaboration with the site. The quality of finish can be identified in the following very broad terms:
* (a) Class 2 applies to surfaces that are to be exposed to view but where appearance is not critical; such surfaces might be the walls of fire escape stairs or plant rooms and columns and beams of structures that are normally viewed in the shade, e.g. car parks and warehouses;
* (b) Class 1 is appropriate to most surfaces exposed to view including the external walls of industrial, commercial and domestic buildings;
* (c) Special class is appropriate to the highest standards of appearance, such as might be found in prestigious buildings, where it is possible to justify the high cost of their production.
* (d) These broad descriptions may be amplified by written descriptions of the method of finish, by photographs, by samples or by reference to existing structures.
### **5.15.3 Type of Surface Finish**
Smooth off-the-form and board marked finishes are not recommended for external use, but where they are specified for interior use the following types may be quoted for the guidance of both designers and contractor. Designers should appreciate that it is virtually impossible to achieve dense, flat, smooth, even coloured blemish free concrete surfaces directly from the form work. Some degree of making good is inevitable, even with precast work.
* (a) Type A finish: This finish is obtained by the use of properly designed formwork or moulds of timber, plywood, plastics, concrete or steel. Small blemishes caused by entrapped air or water may be expected, but the surface should be free from voids, honeycombing or other blemishes.
* (b) Type B finish: This finish can only be obtained by the use of high quality concrete and formwork. The concrete shall be thoroughly compacted and all surfaces shall be true, with clean arises. Only very minor surface blemishes shall occur, with no staining or discoloration from the release agent.
* (c) Type C finish: This finish is obtained by first producing a type B finish. The surface is then improved by carefully removing all fins and other projections, thoroughly washing down, and then filling the most noticeable surface blemishes with a cement and fine aggregate paste to match the colour of the original concrete. The release agent should be carefully chosen to ensure that the concrete surface will not be stained or discoloured. After the concrete has been properly cured, the face shall be rubbed down, where necessary, to produce a smooth and even surface.
### **5.15.4 Production**
The quality of a surface depends on the constituents and proportions of the concrete mix, the efficiency of mixing, the handling and compaction of the concrete and its curing. The characteristics of the formwork and the release agent may also be of critical importance. Requirements may be stated for any aspect of production that might contribute towards the achievement of the required type of quality of finish.
### **5.15.5 Inspection and Making Good**
The surface of the concrete shall be inspected for defects and for conformity with the specification and, where appropriate, for comparison with approved sample finishes. Subject to the strength and durability of the concrete being unimpaired, the making good of surface defects may be permitted but the standard of acceptance shall be appropriate to the type and quality of the finish specified and ensure satisfactory performance and durability. On permanently exposed surfaces great care is essential in selecting the materials and the mix proportions to ensure that the final colour of the faced area blends with the parent concrete in the finished structure.
Voids can be filled with fine mortar, preferably incorporating styrene butadiene rubber (SBR) or polyvinyl acetate (PVA), while the concrete is still green or when it has hardened. Fine cracks can be filled by wiping a cement grout, an SBR, PVA or latex emulsion, a cement/SBR or a cement/PVA slurry across them. Fins and other projections shall be rubbed down.
### **5.15.6 Protection**
High quality surface finishes are susceptible to damage during subsequent construction operations and temporary protection may have to be provided in vulnerable areas. Examples of such protective measures include the strapping of laths to arrises and the prevention of rust being carried from exposed starter bars to finished surfaces.
## **5.16 Formwork**
### **5.16.1 Design of Formwork**
#### 5.16.1.1
Forms shall result in a final structure that conforms to shapes, lines, and dimensions of the members as required by the design drawings and specifications.
#### 5.16.1.2
Forms shall be substantial and sufficiently tight to prevent leakage of mortar.
#### 5.16.1.3
Forms shall be properly braced or tied together to maintain position and shape.
#### 5.16.1.4
Forms and their supports shall be designed so as not to damage previously placed structure.
#### 5.16.1.5
Design of formwork shall include consideration of the following factors:
* (a) Rate and method of placing concrete;
* (b) Construction loads, including vertical, horizontal and impact loads;
* (c) Special form requirements for construction of shells, folded plates, domes, architectural concrete, or similar types of elements.
#### 5.16.1.6
Forms for prestressed concrete members shall be designed and constructed to permit movement of the member without damage during application of prestressing force.
### **5.16.2 Removal of Forms and Shores**
#### 5.16.2.1
No construction loads shall be supported on, nor any shoring removed from, any part of the structure under construction except when that portion of the structure in combination with remaining forming and shoring system has sufficient strength to support safely its weight and loads placed thereon.
#### 5.16.2.2
Sufficient strength shall be demonstrated by structural analysis considering proposed loads, strength of forming and shoring system, and concrete strength data. Structural analysis and concrete strength test data shall be furnished to the engineer when so required.
#### 5.16.2.3
No construction loads exceeding the combinations of superimposed dead load plus specified live load shall be supported on any unshored portion of the structure under construction, unless analysis indicates adequate strength to support such additional loads.
#### 5.16.2.4
Forms shall be removed in such a manner as not to impair safety and serviceability of the structure. All concrete to be exposed by form removal shall have sufficient strength not to be damaged thereby.
#### 5.16.2.5
Forms supporting prestressed concrete members shall not be removed until sufficient prestressing has been applied to enable prestressed members to carry their dead load and anticipated construction loads.
### **5.16.3 Conduits and Pipes Embedded in Concrete**
#### 5.16.3.1
Conduits, pipes and sleeves of any materials not harmful to concrete and within the limitations specified herein shall be permitted to be embedded in concrete with the approval of the engineer, provided they are not considered to replace structurally the displaced concrete.
#### 5.16.3.2
Conduits and pipes of aluminium shall not be embedded in structural concrete unless effectively coated or covered to prevent aluminium concrete reaction or electrolytic action between aluminium and steel.
#### 5.16.3.3
Conduits, pipes, and sleeves passing through a slab, wall, or beam shall not impair significantly the strength of the construction.
#### 5.16.3.4
Conduits and pipes, with their fittings, embedded within a column shall not displace more than 4 percent of the area of cross-section on which strength is calculated or which is required for fire protection.
#### 5.16.3.5
Except when drawings for conduits and pipes are approved by the engineer, conduits and pipes embedded within a slab, wall or beam (other than those merely passing through) shall satisfy the following:
* (a) They shall not be larger in outside dimension than one third (1/3) the overall thickness of slab, wall, or beam in which they are embedded.
* (b) They shall not be spaced closer than 3 diameters or widths on centre.
* (c) They shall not impair significantly the strength of the construction.
#### 5.16.3.6
Conduits, pipes and sleeves shall be permitted to be considered as replacing structurally in compression the displaced concrete provided :
* (a) They are not exposed to rusting or other deterioration.
* (b) They have nominal inside diameter not over 50 mm and are spaced not less than 3 diameters on centres.
#### 5.16.3.7
Pipes and fittings shall be designed to resist effects of the material, pressure, and temperature to which they will be subjected.
#### 5.16.3.8
No liquid, gas, or vapour, except water not exceeding 30o C nor 0.3 N/mm2 pressure, shall be placed in the pipes until the concrete has attained its design strength.
#### 5.16.3.9
In solid slabs, piping, unless it is for radiant heating, shall be placed between the top and bottom reinforcements.
#### 5.16.3.10
Concrete cover for pipes, conduits, and fittings shall be not less than 40 mm for concrete exposed to earth or weather, nor 20 mm for concrete not exposed to weather or in contact with ground.
#### 5.16.3.11
Reinforcement with an area not less than 0.002 times the area of concrete section shall be provided normal to piping.
#### 5.16.3.12
Piping and conduit shall be so fabricated and installed that cutting, bending, or displacement of reinforcement will not be required.
### **5.16.4 Construction Joints**
#### 5.16.4.1
Surface of concrete construction joints shall be cleaned and laitance removed.
#### 5.16.4.2
Immediately before new concrete is placed, all construction joints shall be wetted and standing water removed.
#### 5.16.4.3
Construction joints shall be so made and located as not to impair the strength of the structure. Provision shall be made for transfer of shear and other forces through construction joints. See Sec 6.4.5.9.
#### 5.16.4.4
Construction joints in floors shall be located within the middle third of spans of slabs, beams and girders. Joints in girders shall be offset a minimum distance of two times the width of intersecting beams.
#### 5.16.4.5
Beams, girders, or slabs supported by columns or walls shall not be cast or erected until concrete in the columns or walls is no longer plastic.
#### 5.16.4.6
Beams, girders, haunches, drop panels and capitals shall be placed monolithically as part of a slab system unless otherwise shown in the design drawings or specifications.
## **5.17 Shotcrete**
### **5.17.1 General**
Shotcrete shall be defined as mortar or concrete pneumatically projected at high velocity onto a surface. Except as specified in this Section, shotcrete shall conform to the provisions of this Code regarding plain concrete or reinforced concrete.
### **5.17.2 Proportions and Materials**
Shotcrete proportions shall be such that suitable placement is ensured using the delivery equipment selected, and shall result in finished in place hardened shotcrete meeting the strength requirements of Chapter 6.
### **5.17.3 Aggregate**
Coarse aggregate, if used, shall not exceed 20 mm in size.
### **5.17.4 Reinforcement**
The maximum size of reinforcement shall be 16 mm Ø bars unless it can be demonstrated by preconstruction tests that adequate embedment of larger bars can be achieved. When 16 mm Ø or smaller bars are used, there shall be a minimum clearance of 60 mm between parallel reinforcing bars. When bars larger than 16 mm Ø are permitted, there shall be a minimum clearance between parallel bars equal to six diameters of the bars used. When two curtains of steel are provided, the curtain nearest the nozzle shall have a spacing equal to 12 bar diameters and the remaining curtain shall have a minimum spacing of 6 bar diameters.
Lap splices in reinforcing bars shall be by the noncontact lap splice method with at least 50 mm clearance between bars. The engineer may permit the use of contact lap splices when necessary for the support of the reinforcement, provided it can be demonstrated by means of preconstruction testing that adequate embedment of the bars at the splice can be achieved and provided further that the splices are placed so that the plane containing the centres of the two spliced bars is perpendicular to the surface of the shotcrete work. Shotcrete shall not be applied to spirally tied columns.
### **5.17.5 Preconstruction Tests**
When required by the engineer a test panel shall be shot, cured, cored or sawn, examined and tested prior to commencement of the project. The sample panel shall be representative of the project and simulate job conditions as closely as possible. The panel thickness and reinforcing shall reproduce the thickest and the most congested area specified in the structural design. It shall be shot at the same angle, from a similar distance, using the same nozzleman and with the same concrete mix design that will be used on the project.
### **5.17.6 Rebound**
Any rebound or accumulated loose aggregate shall be removed from the surfaces to be covered prior to placing the initial or any succeeding layers of shotcrete. Rebound shall not be reused as aggregate.
### **5.17.7 Joints**
Except where permitted, unfinished work shall not be allowed to stand for more than 30 minutes unless all edges are sloped thin. Before placing additional material adjacent to previously applied work, sloping and square edges shall be cleaned and wetted.
### **5.17.8 Damage**
An in-place shotcrete which exhibits sags or sloughs, segregation, honeycombing, sand pockets or other obvious defects shall be removed and replaced.
### **5.17.9 Curing**
During the curing periods, shotcrete shall be maintained above 5O C and in moist condition. In initial curing, shotcrete shall be kept continuously moist for 24 hours after placement is complete. Final curing shall continue for seven days after shotcreting, for three days if high early strength cement is used, or until the specified strength is obtained. Final curing shall consist of a fog spray or an approved moisture retaining cover or membrane. In sections of a depth in excess of 300 mm, final curing shall be the same as that for initial curing.
### **5.17.10 Strength Test**
Strength test for shotcrete shall be made by an approved agency on three representative specimens of Core or Cube that have been water soaked for at least 24 hours prior to testing. When the maximum size of aggregate is larger than 10 mm, core specimens shall not be less than 75 mm in diameter or the size of cube specimen shall not be less than 75 mm. When the maximum size of aggregate is 10 mm or smaller, core specimens shall not be less than 50 mm in diameter or the size of cube specimen shall not be less than 50 mm. Specimens shall be taken in accordance with one of the following provisions:
* (a) From work: taken at least one from each shift but not less than one for each 20 m3 of shotcrete;
* (b) From test panels: taken not less than once each shift nor less than one for each 20 m3 of shotcrete placed. When the maximum size aggregate is larger than 10 mm, the test panels shall have a minimum dimension of 450 mm by 450 mm. When the maximum size aggregate is 10 mm or smaller, the test panels shall have a minimum dimension of 300 mm by 300 mm. Panels shall be gunned in the same position as the work, during the course of the work and by the same nozzlemen doing the work. The condition under which the panels are cured shall be the same as the work.
The average strength of three cores from a single panel shall be equal to or exceed 0.85 $f_c'$ with no single core less than 0.75 $f_c'$ . The average strength of three cubes taken from a single panel must equal or exceed $f_c'$ with no individual cube less than $f_c'$ . To check testing accuracy, locations represented by erratic core strengths may be retested.
### **5.17.11 Inspections**
#### 5.17.11.1 Inspection during placement
When shotcrete is used for columns and beams, a special inspector is required. The special inspector shall provide continuous inspection to the placement of the reinforcement and shotcreting and shall submit a statement indicating compliance with the plans and specifications.
#### 5.17.11.2 Visual examination for structural soundness of in-place shotcrete
Completed shotcrete work shall be checked visually for reinforcing bar embedment, voids, rock pocket, sand streaks and similar deficiencies by examining a minimum of three 75 mm cores taken from three areas chosen by the engineer which represent the worst congestion of reinforcing bars occurring in the project. Extra reinforcing bars may be added to non-congested areas and cores may be taken from these areas. The cores shall be examined by the special inspector and a report submitted to the engineer prior to final approval of the shotcrete.
### **5.17.12 Equipment**
The equipment used in construction testing shall be the same equipment used in the work requiring such testing unless substitute equipment is approved by the Engineer.
# Chapter 6: Strength Design of Reinforced Concrete Structures
Source: https://docs.sayed.app/bnbc/part-6-structural-design/chapter-6-strength-design-of-reinforced-concrete-structures
## **6.1 Analysis and Design - General Considerations**
### **6.1.1 Definitions**
The following terms are defined for general use in this Code. Specialized definitions appear in individual chapters.
COLUMN Member with a ratio of height- to least lateral dimension exceeding 3 used primarily to support axial compression load. For a tapered member the least lateral dimension is the average of the top and bottom dimensions of the smaller side.
COMPRESSION A cross section in which the net tensile strain in the CONTROLLED extreme tension steel at nominal strength is less than or SECTIONS equal to the compression-controlled strain limit. COMPRESSION The net tensile strain at balanced strain condition. See Sec CONTROLLED 6.3.3.3. STRAIN LIMIT CONCRETE Mixture of Portland cement or any other hydraulic cement, fine aggregate, coarse aggregate and water with or without admixture.
CONCRETE, Concrete containing lightweight aggregate and an LIGHTWEIGHT equilibrium density as determined by ASTM C567, between 1450 - 1850 kg/m3 .
CONCRETE, Concrete containing only aggregate that conforms to NORMALWEIGHT ASTM C33. CONCRETE, Compressive strength of concrete used in design and SPECIFIED evaluated in accordance with provisions of Sec 5.12, COMPRESSIVE expressed in N/mm2 . STRENGTH OF *′* CONNECTION A region that joins two or more members. CONTRACTION Formed, sawed, or tooled groove in a concrete structure JOINT to create a weakened plane and regulate the location of
Formed, sawed, or tooled groove in a concrete structure to create a weakened plane and regulate the location of cracking resulting from the dimensional change of different parts of the structure.
| COVER, SPECIFIED
CONCRETE | The distance between the outermost surface of embedded
reinforcement and the closest outer surface of the
concrete indicated on design drawing or in project
specification. |
| ---------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| DESIGN
DISPLACEMENT | The total lateral displacement expected for the design-
basis earthquake, as required by provisions of the Code
for earthquake resistant design. |
| DESIGN LOAD
COMBINATION | Combination of factored loads and forces. See Sec 2.7. |
| DESIGN STORY
DRIFT RATIO | Relative difference of design displacement between top
and bottom of a story divided by the story height. |
| DEVELOPMENT
LENGTH | Length of embedded reinforcement, required to develop
the design strength of reinforcement at a critical section.
See Sec 8.2. |
| DROP PANEL | A projection below the slab used to reduce the amount of
negative reinforcement over a column or the minimum
required slab thickness, and to increase the slab shear
strength. See Sec 6.5. |
| EFFECTIVE DEPTH
OF SECTION | Distance measured from extreme compression fibre to
centroid of longitudinal tension reinforcement. |
| EMBEDMENT
LENGTH | Length of embedded reinforcement provided beyond a
critical section. |
| EQUILIBRIUM
DENSITY | Density of lightweight concrete after exposure to a
relative humidity 50 ± 5 percent and temperature of 73.5
± 3.50F for a period of time sufficient to reach constant
density (see ASTM C567) |
| EXTREME
TENSION STEEL | The reinforcement that is the farthest from the extreme
compression fibre. |
| ISOLATION JOINT | A separation between adjoining parts of a concrete
structure, usually a vertical plane, at a designed location
such as to interfere least with performance of the
structure, yet such as to allow relative movement in three
directions and avoid formation of cracks elsewhere in the
concrete and through which all or part of the bonded
reinforcement is interrupted. |
| JOINT | Portion of structure common to intersecting members.
The effective cross sectional area of a joint of a special
moment frame,-. for shear strength computation is
defined in Sec 8.3.7.3. |
| LICENSED DESIGN
PROFESSIONAL | An individual who is licensed to practice structural
design as defined by the statutory requirements of the
professional licensing laws of the state or jurisdiction in
which the project is to be constructed and who is in
responsible charge of the structural design. |
| LOAD, FACTORED | Load, multiplied by appropriate factor, used to proportion
members by strength design method of this Code. |
| MODULUS OF | Ratio of normal stress to corresponding strain for tensile |
| ELASTICITY | or compressive stresses below proportional limit of
material. |
| PEDESTAL | Member with a ratio of height- to-least lateral dimension
less than or equal to 3 used primarily to support axial
compression load. For a tapered member the least lateral
dimension is the average of the top and bottom
dimensions of the smaller side. |
| PLAIN CONCRETE | Structural concrete with no reinforcement or with less
reinforcement than the minimum amount specified for
reinforced concrete. |
| PLASTIC HINGE
REGION | Length of frame element over which flexural yielding is
intended to occur due to earthquake design displacement,
extending not less than a distance\_ℎ\_from the critical
section where flexural yielding occurs. |
| PRECAST
CONCRETE | Structural concrete element cast elsewhere than its final
position in the structure. |
| REINFORCED
CONCRETE | Structural concrete reinforced with no less than the
minimum amount of reinforcement specified in the Code. |
| SEISMIC HOOK | A hook on a stirrup, or cross tie having a bend not less
than 135o, except that circular hoops shall have a bend
not less than 90o. Hooks shall have a $6d_b$ (but not less
than 75 mm) extension that engages the longitudinal
reinforcement and projects into the interior of the stirrup
or hoop. |
| SPIRAL
REINFORCEMENT | Continuously wound reinforcement in the form of a
cylindrical helix. |
| SPLITTING TENSILE
STRENGTH $f_{ct}$ | Tensile strength of concrete determined in accordance
with ASTM C496 as described in ASTM C330. |
| STIRRUPS | Reinforcement used to resist shear and torsion stresses in
a structural member, typically bars, wires, or welded wire
reinforcements either single leg or bent into L, U, or
rectangular shapes and located perpendicular to or at an
angle to longitudinal reinforcement. (The term “stirrups”
is usually used to lateral reinforcement in flexural
members and the term “ties” to those in compression
members. |
| STRENGTH
DESIGN | Nominal strength multiplied by a strength reduction
factor $\phi$. |
| STRENGTH,
NOMINAL | Strength of a member or cross section calculated in
accordance with provisions and assumptions of the
strength design method of this Code before application of
any strength reduction factor. |
| STRENGTH,
REQUIRED | Strength of a member or cross section required to resist
factored loads or related internal moments and forces in
such combination as are stipulated in this Code. |
| STRUCTURAL
CONCRETE | All concrete used for structural purpose including plain
and reinforced concrete. |
| TENSION
CONTROLLED
SECTION | A cross section in which the net tensile strain in the
extreme tensile steel at nominal strength is greater than or
equal to 0.005. |
| TIE | Loop of reinforcing bar or wire enclosing longitudinal
reinforcement. A continuously wound bar or wire in the
form of a circle, rectangle or other polygon shape without
re-entrant corner is acceptable. |
| YIELD STRENGTH | Specified minimum yield strength or yield point of
reinforcement. Yield strength or yield point shall be
determined in tension according to applicable ASTM
standards. |
### **6.1.2 Notation and Symbols**
Unless otherwise explicitly stated, the following units shall be implicit for the corresponding quantities in the design and other expressions provided in this Chapter:
| Lengths | mm |
| ----------------------------------------------------------------------------------------------- | --------------------- |
| Areas | mm2 |
| Second moments of area | mm4 |
| Force (axial, shear) | N |
| Moment, torsion | N-mm |
| Stress, strength | MPa, N/mm2 |
| The following notation apply to Chapters 6 and 8, and Appendices A, I, J, K and L of this Part. | |
* $a$ = Depth of equivalent rectangular stress block as defined in Sec 6.3.2.7.1; (mm)
* $a_v$ = Shear span, equal to distance from center of concentrated load to either: (a) face of support for continuous or cantilevered members, or (b) center of support for simply supported members, mm, Sec 6.4 and Appendix I
* $A_b$ = Area of an individual bar or wire, mm2 , Sec 8.2
* $A_{brg}$ = Net bearing area of the head of stud, anchor bolt, or headed deformed bar, mm2 , Sections 8.2.17 and K.5.3
* $A_c$ = Cross-sectional area of concrete section resisting shear transfer, mm2 , Sec 6.4.5.5
* $A_{ch}$ = Cross-sectional area of a structural member measured to the outside edges of transverse reinforcement, mm2 ,Sections 6.3.9, 8.3.5.4
* $A_{cp}$ = Area enclosed by outside perimeter of concrete cross section, mm2 , see Sections 6.4.4 and 8.3.8.3
* $A_{cs}$ = Cross-sectional area at one end of a strut in a strut-and-tie model, taken perpendicular to the axis of the strut, mm2 , Sec I.3.1 Appendix I.
* $A_{cv}$ = Gross area of concrete section bounded by web thickness and length of section in the direction of shear force considered, mm2 , Sec 8.3.6.2
* $A_{cw}$ = Area of concrete section of an individual pier, horizontal wall segment, or coupling beam resisting shear, mm2 , Sec 8.3.6
* $A_f$ = Area of reinforcement in bracket or corbel resisting factored moment, mm2 , see Sec 6.4.7
* $A_g$ = Gross area of concrete section, mm2 For a hollow section, $A_g$ is the area of the concrete only and does not include the area of the void(s), see Sections 6.2, 6.3, 6.4, 6.6, 6.7, 6.10, 8.3.5
* $A_h$ = Total area of shear reinforcement parallel to primary tension reinforcement in a corbel or bracket, mm2 , see Sec 6.4.7
* $A_j$ = Effective cross-sectional area within a joint in a plane parallel to plane of reinforcement generating shear in the joint, mm2 , see Sec 8.3.7
* $A_l$ = Total area of longitudinal reinforcement to resist torsion, mm2 , Sec 6.4
* $A_{l,min}$ = Minimum area of longitudinal reinforcement to resist torsion, mm2 , see Sec 6.4.4.5.3
* $A_n$ = Area of reinforcement in bracket or corbel resisting tensile force $N_{uc}$, mm2 , see Sec 6.4.7
* $A_{nz}$ = Area of a face of a nodal zone or a section through a nodal zone, mm2 , Sec I.5 Appendix I
* $A_{Nc}$ = Projected concrete failure area of a single anchor or group of anchors, for calculation of strength in tension, mm2 , see Sec K.5.2.1, Appendix K
* $A_{Nco}$ = Projected concrete failure area of a single anchor, for calculation of strength in tension if not limited by edge distance or spacing, mm2 , see Sec K.5.2.1, Appendix K
* $A_o$ = Gross area enclosed by shear flow path, mm2 , Sec 6.4
* $A_{oh}$ = Area enclosed by centerline of outermost closed transverse torsional reinforcement, mm2 , Sec 6.4
* $A_s$ = Area of nonprestressed longitudinal tension reinforcement, mm2 , Sections 6.3, 6.4, 6.6, 6.8,
* $A_{s1}$ = Area of tension reinforcement corresponding to moment of resistance $M_{n1}$ , see Sec 6.3.15.1(b)
* $A_{s2}$ = Area of additional tension steel, see Sec 6.3.15.1(b)
* $A_s'$ = Area of compression reinforcement, mm2 , Sec I.3.5 Appendix I
* $A_{sc}$ = Area of primary tension reinforcement in a corbel or bracket, mm2 , see Sec 6.4.7.3.5
* $A_{se,N}$ = Effective cross-sectional area of anchor in tension, mm2 , Sec K.5.1 Appendix K
* $A_{se,V}$ = Effective cross-sectional area of anchor in shear, mm2 , Sec K. 6.1 Appendix K
* $A_{sf}$ = Area of reinforcement required to balance the longitudinal compressive force in the overhanging portion of the flange of a T- beam, see Sec 6.3.15.2(b)
* $A_{sh}$ = Total cross-sectional area of transverse reinforcement (including crossties) within spacing $s$ and perpendicular to dimension $h_c$, mm2 , Sec 8.3.5
* $A_{si}$ = Total area of surface reinforcement at spacing $s_i$ in the $i$-th layer crossing a strut, with reinforcement at an angle $\alpha_i$ to the axis of the strut, mm2 , Sec I.3.3 Appendix I
* $A_{s,min}$ = Minimum area of flexural reinforcement, mm2 , see Sec 6.3.5
* $A_{st}$ = Total area of nonprestressed longitudinal reinforcement (bars or steel shapes), mm2 , Sec 6.3.3
* $A_{sx}$ = Area of structural steel shape, pipe, or tubing in a composite section, mm2 , Sec 6.3
* $A_t$ = Area of one leg of a closed stirrup resisting torsion within spacing $s$, mm2 , Sec 6.4
* $A_{tr}$ = Total cross-sectional area of all transverse reinforcement within spacing $s$ that crosses the potential plane of splitting through the reinforcement being developed, mm2 , Sec 8.2.3
* $A_{ts}$ = Area of nonprestressed reinforcement in a tie, mm2 , Sec I.4.1 Appendix I
* $A_v$ = Area of shear reinforcement spacing $s$, mm2 , Sections 6.4, 6.12
* $A_{Vc}$ = Projected concrete failure area of a single anchor or group of anchors, for calculation of strength in shear, mm2 , see Sec K.6.2.1 Appendix K
* $A_{Vco}$ = Projected concrete failure area of a single anchor, for calculation of strength in shear, if not limited by corner influences, spacing, or member thickness, mm2 , see Sec K.6.2.1 Appendix K
| $A_{vd}$ | = Total area of reinforcement in each group of diagonal bars in a
diagonally reinforced coupling beam, mm2, Sec 8.3.6 |
| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| $A_{vf}$ | = Area of shear-friction reinforcement, mm2, Sec 6.4.5 |
| $A_{vh}$ | = Area
of
shear
reinforcement
parallel
to
flexural tension
reinforcement within spacing $s_2$, mm2, Sec 6.4 |
| $A_{v,min}$ | = Minimum area of shear reinforcement within spacing s, mm2, see
Sec 6.4.3.5 |
| $A_1$ | = Loaded area, mm2, Sec 6.3 |
| $A_2$ | = Area of the lower base of the largest frustumof a pyramid, cone, or
tapered wedge contained wholly within the support and having for
its upper base the loaded area, and having side slopes of 1 vertical
to 2 horizontal, mm2, Sec 6.3 |
| $b$ | = Width of compression face of member, mm, Sec 6.3 |
| $b_o$ | = Perimeter of critical section for shear in slabs and footings, mm, see
Sec 6.4.10.1.2 |
| $b_s$ | = Width of strut, mm, Sec I.3.3 Appendix I |
| $b_t$ | = Width of that part of cross section containing the closed stirrups
resisting torsion, mm, Sec 6.4 |
| $b_v$ | = Width of cross section at contact surface being investigated for
horizontal shear, mm, Sec 6.12 |
| $b_w$ | = Web width, or diameter of circular section, mm, Sections 6.3, 6.4,
8.2, 8.3.4 |
| $b_1$ | = Dimension of the critical section $b_o$ measured in the direction of the
span for which moments are determined, mm, Sec 6.5 |
| $b_2$ | = Dimension of the critical section $b_o$ measured in the direction
perpendicular to $b_1$, mm, Sec 6.5 |
| $c$ | = Distance from extreme compression fiber to neutral axis, mm,
Sections 6.2, 6.3, 6.6, 8.3.6 |
| $C_a, C_b$ | = Moment coefficients, Sec 6.5.8 |
| $c_{ac}$ | = Critical edge distance required to develop the basic concrete
breakout strength of a post- installed anchor in uncracked concrete
without supplementary reinforcement to control splitting, mm, see
Sec K.8.6 Appendix K |
* $c_{a,max}$ = Maximum distance from center of anchor shaft to the edge of concrete, mm, Sec K.5.2.3 Appendix K
* $c_{a,min}$ = Minimum distance from center of anchor shaft to the edge of concrete, mm, Sec K.8.6 Appendix K
* $c_{a1}$ = Distance from the center of an anchor shaft to the edge of concrete in one direction, mm. If shear is applied to anchor, $c_{a1}$ is taken in the direction of the applied shear. If tension is applied to the anchor, $c_{a1}$ is the minimum edge distance, Sec K.5.2 Appendix K
* $c_{a2}$ = Distance from center of an anchor shaft to the edge of concrete in the direction perpendicular to $c_{a1}$, mm, Sec K.5.4 Appendix K
* $c_b$ = Smaller of: (a) the distance from center of a bar or wire to nearest concrete surface, and (b) one-half the center-to-center spacing of bars or wires being developed, mm, Sec 8.2.3
* $c_c$ =Clear cover of reinforcement, mm, see Sec 6.3.6.4
* $c_1$ = Dimension of rectangular or equivalent rectangular column, capital, or bracket measured in the direction of the span for which moments are being determined, mm, Sections 6.4, 6.5, 8.3.4
* $c_2$ = Dimension of rectangular or equivalent rectangular column, capital, or bracket measured in the direction perpendicular to $c_1$, mm, Sec 6.5
* $C$ = Cross-sectional constant to define torsional properties of slab and beam, see Sec 6.5.6.4.2
* $C_m$ = Factor relating actual moment diagram to an equivalent uniform moment diagram, Sec 6.3
* $d$ = Distance from extreme compression fiber to centroid of longitudinal tension reinforcement, mm, Sections 6.2, 6.3, 6.4, 6.6, 6.12, 8.1.5, 8.2.7, 8.3.4
* $d'$ = Distance from extreme compression fiber to centroid of longitudinal compression reinforcement, mm, Sec 6.2
* $d_a$ = Outside diameter of anchor or shaft diameter of headed stud, headed bolt, or hooked bolt, mm, see Sec K.8.4, Appendix K
* $d_a'$ = Value substituted for $d_a$ when an oversized anchor is used, mm, see Sec K.8.4, Appendix K
* $d_{pile}$ = Diameter of pile at footing base, mm, Sec 6.8
* $d_t$ = Distance from extreme compression fiber to centroid of extreme layer of longitudinal tension steel, mm, Sections 6.2, 6.3
* $D$ = Dead loads, or related internal moments and forces, Sections 6.1, 6.2, 6.11
* $e_h$ = Distance from the inner surface of the shaft of a J- or L-bolt to the outer tip of the J- or L-bolt, mm, Sec K.5.3 Appendix K
* $e_N'$ = Distance between resultant tension load on a group of anchors loaded in tension and the Centroid of the group of anchors loaded in tension, mm; $e_N'$ is always positive, Sec K.5.2 Appendix K
* $e_V'$ = Distance between resultant shear load on a group of anchors loaded in shear in the same direction, and the centroid of the group of anchors loaded in shear in the same direction, mm; $e_V'$ is always positive, Sec K.6.2 Appendix K
* $E$ = Load effects of earthquake, or related internal moments and forces, Sections 6.2, 8.3.6
* $E_c$ = Modulus of elasticity of concrete, MPa see Sec 6.1.7.1, 6.2, 6.3, 6.6, 6.9
* $E_{cb}$ = Modulus of elasticity of beam concrete, MPa, Sec 6.5
* $E_{cs}$ = Modulus of elasticity of slab concrete, MPa, Sec 6.5
* $EI$ = Flexural stiffness of compression member,N⋅mm2, see Sec 6.3.10.6
* $E_s$ = Modulus of elasticity of reinforcement and structural steel, MPa, see Sections 6.1.7.2, 6.3, 6.6
* $f_c'$ = Specified compressive strength of concrete, MPa, Sections 6.1 to 6.4, 6.6, 6.9, 8.2, 8.3, Appendices I, K
* $f_{ce}$ = Effective compressive strength of the concrete in a strut or a nodal zone, MPa, Sec 6.8.5, I.3.1 Appendix I
* $f_{ct}$ = Average splitting tensile strength of lightweight concrete, MPa, See Sec 6.1.8.1 Sections 6.1, 6.4, 8.2.3.4
* $f_d$ = Stress due to unfactored dead load, at extreme fiber of section where tensile stress is caused by externally applied loads, MPa, Sec 6.4
* $f_{pc}$ = Compressive stress in concrete at centroid of cross section resisting externally applied loads or at junction of web and flange when the centroid lies within the flange, MPa. (In a composite member, $f_{pc}$ is the resultant compressive stress at centroid of composite section, or at junction of web and flange when the centroid lies within the flange, due to both prestress and moments resisted by precast member acting alone), Sec 6.4
* $f_r$ = Modulus of rupture of concrete, MPa, see Sections 6.2.5, 6.6
* $f_s$ = Calculated tensile stress in reinforcement at service loads, MPa, Sec 6.3
* $f_s'$ = Stress in compression reinforcement under factored loads, MPa, Sec I.3.5 Appendix I
* $f_{uta}$ = Specified tensile strength of anchor steel, MPa, Appendix K
* $f_y$ = Specified yield strength of reinforcement, MPa, Sections 6.2 to 6.4, 6.6, 6.9, 6.12, 8.1 to 8.3, I.4.1
* $f_{ya}$ = Specified yield strength of anchor steel, MPa, Sec K.4.4 Appendix K
* $f_{yt}$ = Specified yield strength of transverse reinforcement, MPa, Sections 6.3, 6.4, 8.3.3.4
* $F$ = Loads due to weight and pressures of fluids with well-defined densities and controllable maximum heights, or related internal moments and forces, Sec 6.2
* $F_n$ = Nominal strength of a strut, tie, or nodal zone, N, Sec I.2.6 Appendix I
* $F_{nn}$ = Nominal strength at face of a nodal zone, N, Sec I.5.1 Appendix I
* $F_{ns}$ = Nominal strength of a strut, N, Sec I.3.1 Appendix I
* $F_{nt}$ = Nominal strength of a tie, N, Sec I.4.1 Appendix I
* $F_u$ = Factored force acting in a strut, tie, bearing area, or nodal zone in a strut-and-tie model, N, Sec I.2.6 Appendix I
* $h$ = Overall thickness or height of member, mm, Sections 6.2 to 6.4, 6.6, 6.11, 6.12, 8.1.6, 8.3.4, I.1
* $h_a$ = Thickness of member in which an anchor is located, measured parallel to anchor axis, mm, Sec K.6.2 Appendix K
* $h_c$ = Cross-sectional dimension of member core measured to the outside edges of the transverse reinforcement composing area $A_{sh}$,mm, Sec 8.3.5
* $h_{ef}$ = Effective embedment depth of anchor, mm, see Sec K.5.2, Appendix K
* $h_f$ = Thickness of overhanging portion of the flange of a T-beam, Sec 6.3.15.2(b)
* $h_v$ = Depth of shear head cross section, mm, Sec 6.4
* $h_w$ = Height of entire wall from base to top or height of the segment of wall considered, mm, Sections 6.4, 8.3.6
* $h_x$ = Maximum center-to-center horizontal spacing of crossties or hoop legs on all faces of the column, mm, Sec 8.3.5
* $H$ = Loads due to weight and pressure of soil, water in soil, or other materials, or related internal moments and forces, Sec 6.2
* $I$ = Moment of inertia of section about centroidal axis, mm4 , Sections 6.3, 6.4
* $I_b$ = Moment of inertia of gross section of beam about centroidal axis, mm4 , Sec 6.5.6
* $I_{cr}$ = Moment of inertia of cracked section transformed to concrete, mm4 , Sec 6.2
* $I_e$ = Effective moment of inertia for computation of deflection, mm4 , Sec 6.2.5
* $I_g$ = Moment of inertia of gross concrete section about centroidal axis, neglecting reinforcement, mm4 , Sections 6.2, 6.3, 6.6
* $I_s$ = Moment of inertia of gross section of slab about centroidal axis defined for calculating $\alpha_f$ and $\beta_t$, mm4 , Sec 6.5
* $I_{se}$ = Moment of inertia of reinforcement about centroidal axis of member cross section, mm4 , Sec 6.3
* $I_{sx}$ = Moment of inertia of structural steel shape, pipe, or tubing about centroidal axis of composite member cross section, mm4 , Sec 6.3
* $k$ = Effective length factor for compression members, Sections 6.3, 6.6
* $k_c$ = Coefficient for basic concrete breakout strength in tension, Sec K.5.2 Appendix K
* $k_{cp}$ = Coefficient for pryout strength, Sec K.6.3 Appendix K
* $K_{tr}$ = Transverse reinforcement index, Sec 8.2.3.3
* $l$ = Span length of beam or one-way slab; clear projection of cantilever, mm, Sec 6.2
* $l_a$ = Additional embedment length beyond centerline of support or point of inflection, mm, Sec 8.2.8
* $l_a$ = Length of clear span in short direction, Sec 6.5.8
* $l_b$ = Length of clear span in long direction, Sec 6.5.8
* $l_c$ = Length of compression member in a frame, measured center-tocenter of the joints in the frame, mm, Sections 6.3, 6.6
* $l_d$ = Development length in tension of deformed bar, deformed wire, plain and deformed welded wire reinforcement, or mm, Sections 6.9, 8.2.3, 8.3.6
* $l_{dc}$ = Development length in compression of deformed bars and deformed wire, mm, Sec 8.2.4
* $l_{dh}$ = Development length in tension of deformed bar or deformed wire with a standard hook, measured from critical section to outside end of hook (straight embedment length between critical section and start of hook \[point of tangency] plus inside radius of bend and one bar diameter), mm, see Sections 8.2.6, 8.3.6
* $l_{dt}$ = Development length in tension of headed deformed bar, measured from the critical section to the bearing face of the head, mm, Sections 8.2.17, 8.3.6
* $l_e$ = Load bearing length of anchor for shear, mm, Sec K.6.2.2, Appendix K
* $l_n$ = Length of clear span measured face-to-face of supports, mm, Sections 6.1 to 6.5, 6.10, 8.2.9, 8.3.4
* $l_o$ = Length, measured from joint face along axis of structural member, over which special transverse reinforcement must be provided, mm, Sec 8.3.5
* $l_t$ = Span of member under load test, taken as the shorter span for twoway slab systems, mm. Span is the smaller of: (a) distance between centers of supports, and (b) clear distance between supports plus thickness ℎ of member. Span for a cantilever shall be taken as twice the distance from face of support to cantilever end, Sec 6.11
* $l_u$ = Unsupported length of compression member, mm, Sec 6.3.10
| $l_v$ | = | Length of shear head arm from centroid of concentrated load or
reaction, mm, Sec 6.4 |
| --------- | - | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| $l_w$ | = | Length of entire wall or length of segment of wall considered in
direction of shear force, mm, Sections 6.4, 6.6, 8.3.6 |
| $l_1$ | = | Length of span in direction that moments are being determined,
measured center-to-center of supports, mm, Sec 6.5 |
| $l_1$ | = | Length of clear span in direction that moment are being
determined, Sec 6.5.8 |
| $l_2$ | = | Length of clear span transverse to $l_1$, Sec 6.5.8 |
| $l_2$ | = | Length of span in direction perpendicular to $l_1$, measured center-to-
center of supports, mm, Sec 6.5.6 |
| $L$ | = | Live loads, or related internal moments and forces, Sections 6.1, 6.2,
6.11, 8.3.12 |
| $L_r$ | = | Roof live load, or related internal moments and forces, Sec 6.2 |
| $M_a$ | = | Maximum moment in member due to service loads at stage
deflection is computed, N⋅mm, Sections 6.2, 6.6 |
| $M_a$ | = | Moment in the short direction, Sec 6.5.8 |
| $M_b$ | = | Moment in the long direction, Sec 6.5.8 |
| $M_c$ | = | Factored moment amplified for the effects of member curvature
used for design of compression member, N⋅mm, see Sec 6.3.10.6 |
| $M_{cr}$ | = | Cracking moment, N⋅mm, see Sec 6.2.5.2.3, Sections 6.2, 6.6 |
| $M_{cre}$ | = | Moment causing flexural cracking at section due to externally
applied loads, N⋅mm, Sec 6.4 |
| $M_m$ | = | Factored moment modified to account for effect of axial
compression, N⋅mm, Sec 6.4.2 |
| $M_{max}$ | = | Maximum factored moment at section due to externally applied
loads, N⋅mm, Sec 6.4 |
| $M_n$ | = | Nominal flexural strength at section, N⋅mm, Sections 6.4, 6.6, 8.2.8,
8.3.12 |
| $M_{n1}$ | = | Nominal flexural strength at section without compression steel, see
Sec 6.3.15.1(b), and moment of resistance developed by
compression in the overhanging portion of the T-flange, Sec 6.3.15.2 |
* $M_{n2}$ = Additional nominal flexural strength at section due to added compression steel $A_s'$ and additional tension steel $A_{s2}$, Sec 6.3.15.1, and moment of resistance developed by the web of a T-beam, Sec 6.3.15.2
* $M_o$ = Total factored static moment, N⋅mm, Sec 6.5
* $M_p$ = Required plastic moment strength of shear head cross section, N⋅mm, Sec 6.4
* $M_{pr}$ = Probable flexural strength of members, with or without axial load, determined using the properties of the member at the joint faces assuming a tensile stress in the longitudinal bars of at least $1.25f_y$ and a strength reduction factor, $\phi$, of 1.0, N⋅mm, Sec 8.3.8
* $M_s$ = Factored moment due to loads causing appreciable sway, N⋅mm, Sec 6.3
* $M_u$ = Factored moment at section, N⋅mm, Sections 6.3, 6.4, 6.5, 6.6, 8.3.6
* $M_{ua}$ = Moment at mid height of wall due to factored lateral and eccentric vertical loads, not including $P\Delta$ effects, N⋅mm, Sec 6.6
* $M_v$ = Moment resistance contributed by shear head reinforcement, N⋅mm, Sec 6.4
* $M_1$ = Smaller factored end moment on a compression member, to be taken as positive if member is bent in single curvature, and negative if bent in double curvature, N⋅mm, Sec 6.3
* $M_{1ns}$ = Factored end moment on a compression member at the end at which $M_1$ acts, due to loads that cause no appreciable side sway, calculated using a first-order elastic frame analysis, N⋅mm, Sec 6.3
* $M_{1s}$ = Factored end moment on compression member at the end at which $M_1$ acts, due to loads that cause appreciable side sway, calculated using a first-order elastic frame analysis, N⋅mm, Sec 6.3
* $M_2$ = Larger factored end moment on compression member. If transverse loading occurs between supports, $M_2$ is taken as the largest moment occurring in member. Value of $M_2$ is always positive, N⋅mm, Sec 6.3
* $M_{2,min}$ = Minimum value of $M_2$, N⋅mm, Sec 6.3
* $M_{2ns}$ = Factored end moment on compression member at the end at which $M_2$ acts, due to loads that cause no appreciable side sway, calculated using a first-order elastic frame analysis, N⋅mm, Sec 6.3
* $M_{2s}$ = Factored end moment on compression member at the end at which $M_2$ acts, due to loads that cause appreciable sidesway, calculated using a first-order elastic frame analysis, N⋅mm, Sec 6.3
* $n$ = Number of items, such as strength tests, bars, wires, monostrand anchorage devices, anchors, or shear head arms, Sec 6.4, 8.2, K.1 Width of flight, Figure 6.6.29.
* $N_b$ = Basic concrete breakout strength in tension of a single anchor in cracked concrete, N, Sec K.5.2.2
* $N_{cb}$ = Nominal concrete breakout strength in tension of a single anchor, N, see Sec K.5.2.1
* $N_{cbg}$ = Nominal concrete breakout strength in tension of a group of anchors, N, Sec K.5.2.1
* $N_n$ = Nominal strength in tension, N, Sec K.3.3
* $N_p$ = Pullout strength in tension of a single anchor in cracked concrete, N, Sections K.2.3 K.3.3, K.5.3
* $N_{pn}$ = Nominal pullout strength in tension of a single anchor, N, Sections K.4.1, K.5.3
* $N_{sa}$ = Nominal strength of a single anchor or group of anchors in tension as governed by the steel strength, N, Sections K.4.1, K.5.1
* $N_{sb}$ = Side-face blowout strength of a single anchor, N, Sec K.4.1
* $N_{sbg}$ = Side-face blowout strength of a group of anchors, N, Sections K.4.1, K.5.4
* $N_u$ = Factored axial force normal to cross section occurring simultaneously with $V_u$ or $T_u$; to be taken as positive for compression and negative for tension, N, Sec 6.4
* $N_{ua}$ = Factored tensile force applied to anchor or group of anchors, N, Sections K.4.1, K.7
* $N_{uc}$ = Factored horizontal tensile force applied at top of bracket or corbel acting simultaneously with $V_u$, to be taken as positive for tension, N, Sec 6.4
* $p_{cp}$ = Outside perimeter of concrete cross section, mm, Sec 6.4.4.1
* $p_h$ = Perimeter of centerline of outermost closed transverse torsional reinforcement, mm, Sec 6.4
| $P_b$ | = | Nominal axial strength at balanced strain conditions, N, Sections 6.2,
6.3.3 |
| ----------- | - | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| $P_c$ | = | Critical buckling load, N, Sec 6.3.10 |
| $P_n$ | = | Nominal axial strength of cross section, N, Sections 6.2, 6.3, 6.6 |
| $P_{n,max}$ | = | Maximum allowable value of $P_n$, N, Sec 6.3.3 |
| $P_o$ | = | Nominal axial strength at zero eccentricity, N, Sec 6.3 |
| $P_s$ | = | Unfactored axial load at the design (mid height) section including
effects of self-weight, N, Sec 6.6 |
| $P_u$ | = | Factored axial force; to be taken as positive for compression and
negative for tension, N, Sections 6.3, 6.6 |
| $q_{Du}$ | = | Factored dead load per unit area, Sec 6.5 |
| $q_{Lu}$ | = | Factored live load per unit area, Sec 6.5 |
| $q_u$ | = | Factored load per unit area, Sec 6.5 |
| $Q$ | = | Stability index for a story, Sec 6.3.10.5.2 |
| $r$ | = | Radius of gyration of cross section of a compression member, mm,
Sec 6.3 |
| $R$ | = | Rain load, or related internal moments and forces, Sec 6.2 |
| $s$ | = | Center-to-center
spacing
of
items,
such
as
longitudinal
reinforcement, transverse reinforcement, wires, or anchors, mm,
Sections 6.3, 6.4, 6.9, 6.11, 6.12, 8.2.3, 8.3.4, Appendix K |
| $s_i$ | = | Center-to-center spacing of reinforcement in the i-th layer adjacent
to the surface of the member, mm, Sec I.3.3 |
| $s_o$ | = | Center-to-center spacing of transverse reinforcement within the
length $l_o$, mm, Sec 8.3.10 |
| $s_s$ | = | Sample standard deviation, MPa, Sec K.1 |
| $s_2$ | = | Center-to-center
spacing
of
longitudinal
shear
or
torsion
reinforcement, mm, Sec 6.4 |
| $t$ | = | Wall thickness of hollow section, mm, Sec 6.4 |
| $T$ | = | Cumulative effect of temperature, creep, shrinkage, differential
settlement, and shrinkage-compensating concrete, Sec 6.2 |
* $T_n$ = Nominal torsional moment strength, N⋅mm, Sec 6.4
* $T_u$ = Factored torsional moment at section, N⋅mm, Sec 6.4
* $U$ = Required strength to resist factored loads or related internal moments and forces, Sec 6.2
* $v_n$ = Nominal shear stress, MPa, Sections 6.4, 8.3.8
* $V_b$ = Basic concrete breakout strength in shear of a single anchor in cracked concrete, N, Sec K.6.2
* $V_c$ = Nominal shear strength provided by concrete, N, Sections 6.1, 6.4, 6.5, 8.3.8
* $V_{cb}$ = Nominal concrete breakout strength in shear of a single anchor, N, Sections K.4.1, K.6.2
* $V_{cbg}$ = Nominal concrete breakout strength in shear of a group of anchors, N, Sections K.4.1, K.6.2
* $V_{ci}$ = Nominal shear strength provided by concrete when diagonal cracking results from combined shear and moment, N, Sec 6.4
* $V_{cp}$ = Nominal concrete pryout strength of a single anchor, N, Sec K.6.3.1
* $V_{cpg}$ = Nominal concrete pryout strength of a group of anchors, N, Sec K.6.3.1
* $V_{cw}$ = Nominal shear strength provided by concrete when diagonal cracking results from high principal tensile stress in web, N, Sec 6.4
* $V_d$ = Shear force at section due to unfactored dead load, N, Sec 6.4
* $V_e$ = Design shear force corresponding to the development of the probable moment strength of the member, N, Sec 8.3.8
* $V_n$ = Nominal shear strength, N, Sections 6.1, 6.3, 6.4, 8.3.6, K.3.3
* $V_{nh}$ = Nominal horizontal shear strength, N, Sec 6.12
* $V_s$ = Nominal shear strength provided by shear reinforcement, N, Sec 6.4
* $V_{sa}$ = Nominal strength in shear of a single anchor or group of anchors as governed by the steel strength, N, see Sections K.3.3, K.6.1.1, K.6.1.2
* $V_u$ = Factored shear force at section, N, Sections 6.4, 6.5, 6.12, 8.2.7, 8.3.6
* $V_{ua}$ = Factored shear force applied to a single anchor or group of anchors, N, K.4.1
* $V_{ug}$ = Factored shear force on critical section of two-way slab action due to gravity loads, N, Sec 8.3.12
* $V_{us}$ = Factored horizontal shear in a story, N, Sec 6.3
* $w$ = Uniform load, Sec 6.5.8
* $w_c$ = Density (unit weight) of normal weight concrete or equilibrium density of light weight concrete, kg/m3 , Sections 6.1, 6.2
* $w_u$ = Factored load per unit length of beam or one way slab, Sec 6.1
* $W$ = Wind load, or related internal moments and forces, Sec 6.2
* $x$ = Shorter overall dimension of rectangular part of cross section, mm, Sec 6.5
* $y$ = Longer overall dimension of rectangular part of cross section, mm, Sec 6.5
* $y_t$ = Distance from centroidal axis of gross section, neglecting reinforcement, to tension face, mm, Sections 6.2, 6.4
* $\alpha$ = Angle defining the orientation of reinforcement, Sections 6.4, I.3.3
* $\alpha_c$ = Coefficient defining the relative contribution of concrete strength to nominal wall shear strength, Sec 8.3.6
* $\alpha_f$ = Ratio of flexural stiffness of beam section to flexural stiffness of a width of slab bounded laterally by centerlines of adjacent panels (if any) on each side of the beam, Sections 6.2, 6.4.2, 6.5.6, 6.5.8
* $\alpha_{fm}$ = Average value of $\alpha_f$ for all beams on edges of a panel, Sec 6.2
* $\alpha_{f1}$ = $\alpha_f$ in direction of $l_1$, Sec 6.5
* $\alpha_{f2}$ = $\alpha_f$ in direction of $l_2$, Sec 6.5
* $\alpha_i$ = Angle between the axis of a strut and the bars in the i-th layer of reinforcement crossing that strut, Sec I.3.3
* $\alpha_s$ = Constant used to compute $V_c$ in slabs and footings, Sec 6.4
* $\alpha_v$ = Ratio of flexural stiffness of shear head arm to that of the surrounding composite slab section, Sec 6.4.10
* $\beta$ = Ratio of long to short dimensions: clear spans for two-way slabs, Sec 6.2.5 sides of column, concentrated load or reaction area, Sec 6.4.10; or sides of a footing, Sections 6.2, 6.4, 6.8.4
* $\beta_b$ = Ratio of area of reinforcement cut off to total area of tension reinforcement at section, Sec 8.2.7
* $\beta_{dns}$ = Ratio used to account for reduction of stiffness of columns due to sustained axial loads, Sec 6.3.10
* $\beta_{ds}$ = Ratio used to account for reduction of stiffness of columns due to sustained lateral loads, Sec 6.3.10.4
* $\beta_n$ = Factor to account for the effect of the anchorage of ties on the effective compressive strength of a nodal zone, Sec I.5.2
* $\beta_s$ = Factor to account for the effect of cracking and confining reinforcement on the effective compressive strength of the concrete in a strut, Sec I.3.2
* $\beta_t$ = Ratio of torsional stiffness of edge beam section to flexural stiffness of a width of slab equal to span length of beam, center-to-center of supports, Sec 6.5.6.4
* $\beta_1$ = Factor relating depth of equivalent rectangular compressive stress block to neutral axis depth, Sec 6.3.2.7
* $\gamma_f$ = Factor used to determine the unbalanced moment transferred by flexure at slab-column connections, Sections 6.4, 6.5.5.3
* $\gamma_s$ = Factor used to determine portion of reinforcement located in center band of footing, Sec 6.8.4.4
* $\gamma_v$ = Factor used to determine the unbalanced moment transferred by eccentricity of shear at slab-column connections, Sec 6.4.10.7
* $\delta$ = Moment magnification factor to reflect effects of member curvature between ends of compression member, Sec 6.3
* $\delta_s$ = Moment magnification factor for frames not braced against side sway, to reflect lateral drift resulting from lateral and gravity loads, Sec 6.3
* $\delta_u$ = Design displacement, mm, Sec 8.3.6
* $\Delta_{cr}$ = Computed, out-of-plane deflection at mid height of wall corresponding to cracking moment, $M_{cr}$, mm, Sec 6.6
* $\Delta_n$ = Computed, out-of-plane deflection at mid height of wall corresponding to nominal flexural strength, $M_n$, mm, Sec 6.6
* $\Delta_o$ = Relative lateral deflection between the top and bottom of a story due to lateral forces computed using a first-order elastic frame analysis and stiffness values satisfying Sec 6.3
* $\Delta_r$ = Difference between initial and final (after load removal) deflections for load test or repeat load test, mm, Sec 6.11
* $\Delta_s$ = Computed, out-of-plane deflection at mid height of wall due to service loads, mm, Sec 6.6
* $\Delta_u$ = Computed deflection at mid height of wall due to factored loads, mm, Sec 6.6
* $\Delta_1$ = Measured maximum deflection during first load test, mm, Sec 6.11.5.2
* $\Delta_2$ = Maximum deflection measured during second load test relative to the position of the structure at the beginning of second load test, mm, Sec 6.11.5.2
* $\varepsilon_t$ = Net tensile strain in extreme layer of longitudinal tension steel at nominal strength, creep, shrinkage, and temperature, Sections 6.1 to 6.3
* $\theta$ = Angle between axis of strut, compression diagonal, or compression field and the tension chord of the member, Sec 6.4.4
* $\lambda$ = Modification factor reflecting the reduced mechanical properties of lightweight concrete, all relative to normal weight concrete of the same compressive strength, Sections 6.1.8.1, 6.2, 6.4.5.4, 6.9, 8.2.3.4, 8.2.6.2, 8.2.10.2, 8.3.6, I.3.2, K.5.2
* $\lambda_\Delta$ = Multiplier for additional deflection due to long-term effects, Sec 6.2.5.2.5
* $\mu$ = Coefficient of friction, Sec 6.4.5.4.3
* $\xi$ = Time-dependent factor for sustained load, Sec 6.2.5.2
* $\rho$ = Ratio of $A_s$ to $bd$, Sections 6.4, 6.5, 8.3.4
* $\rho'$ = Ratio of $A_s'$ to $bd$, Sections 6.2, 6.3.15.1
* $\rho_b$ = Ratio of $A_s$ to $bd$ producing balanced strain conditions, Sections 6.3.3.2, 6.5, 6.6
* $\rho_f$ = Ratio of $A_{sf}$ to $b_{wd}$, Sec 6.3.15.2
* $\rho_l$ = Ratio of area of distributed longitudinal reinforcement to gross concrete area perpendicular to that reinforcement, Sections 6.4, 6.6, 8.3.6
* $\rho_{max}$ = Maximum reinforcement ratio allowed for beams corresponding to $\varepsilon_t$ = 0.004, Sec 6.3.15.1
| $\rho_s$ | = Ratio of volume of spiral reinforcement to total volume of core
confined by the spiral (measured out-to-out of spirals), Sections 6.3,
8.3.5 |
| ------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| $\rho_t$ | = Ratio of area distributed transverse reinforcement to gross concrete
area perpendicular to that reinforcement, Sections 6.4, 6.6, 8.3.6 |
| $\rho_t$ | = Ratio of tie reinforcement area to area of contact surface, Sec 6.12.5.3 |
| $\rho_w$ | = Ratio of $A_s$ to $b_{wd}$, Sections 6.3.15.2, 6.4 |
| $\phi$ | = Strength reduction factor, see Sec 6.2.3, Sections 6.1 to 6.6, 6.9, 6.11,
6.12, 8.3.12, I.2.6, K.2.1 |
| $\psi_{c,N}$ | = Factor used to modify tensile strength of anchors based on presence
or absence of cracks in concrete, Sec K.5.2 |
| $\psi_{c,P}$ | = Factor used to modify pullout strength of anchors based on presence
or absence of cracks in concrete, Sec K.5.3 |
| $\psi_{c,V}$ | = Factor used to modify shear strength of anchors based on presence
or absence of cracks in concrete and presence or absence of
supplementary reinforcement, Sec K.6.2 for anchors in shear |
| $\psi_e$ | = Factor used to modify development length based on reinforcement
coating, Sec 8.2.3 |
| $\psi_{ec,N}$ | = Factor used to modify tensile strength of anchors based on
eccentricity of applied loads, Sec K.5.2 |
| $\psi_{ec,V}$ | = Factor used to modify shear strength of anchors based on
eccentricity of applied loads, Sec K.6.2 |
| $\psi_{ed,N}$ | = Factor used to modify tensile strength of anchors based on proximity
to edges of concrete member, Sec K.5.2 |
| $\psi_{ed,V}$ | = Factor used to modify shear strength of anchors based on proximity
to edges of concrete member, Sec K.6.2 |
| $\psi_{h,V}$ | = Factor used to modify shear strength of anchors located in concrete
members with $h_{ef} \leq 1.5c_{a1}$, Sec K.6.2 |
| $\psi_s$ | = Factor used to modify development length based on reinforcement
size, Sec 8.2.3 |
| $\psi_t$ | = Factor used to modify development length based on reinforcement
location, Sec 8.2.3 |
| $\psi_w$ | = Factor used to modify development length for welded deformed wire
reinforcement in tension, Sec 8.2.18 |
### 6.1.3 General
#### 6.1.3.1
Members shall be designed for adequate strength in accordance with the provisions of this Chapter, using load factors specified in Sec 2.7.3.1 and strength reduction factors $\phi$ in Sec 6.2.3.1.
#### 6.1.3.2
Design of reinforced concrete members using Working Stress Design method (Appendix J) is also permitted.
#### 6.1.3.3
Structures and structural members shall be designed to have design strength at all sections at least equal to the required strength (U) calculated for the factored loads and forces in such combinations as are stipulated in Chapter 2, Loads. The nominal strength provided for the section multiplied by the strength reduction factor $\phi$ shall be equal to or greater than the calculated required strength U.
#### 6.1.3.4
Members shall also meet all the other requirements of this Code to ensure adequate performance at service loads.
#### 6.1.3.5
Design strength of reinforcement represented by the values of $f_y$ and $f_{yt}$ used in design calculations shall not exceed 550 MPa, and for transverse reinforcement in Sections 6.3.9.3 and 8.3. $f_y$ or $f_{yt}$ may exceed 420 MPa, only if the ratio of the actual tensile strength to the actual yield strength is not less than 1.20, and the elongation percentage is not less than 16.
#### 6.1.3.6
For structural concrete, $f_c'$ shall not be less than 17 MPa. No maximum value of $f_c'$ shall apply unless restricted by a specific Code provision.
### 6.1.4 Loading
#### 6.1.4.1
Loads and their combinations shall be in accordance with the requirements specified in Chapter 2 of this Part.
#### 6.1.4.2
Structures shall be designed to resist all applicable loads.
#### 6.1.4.3
Effects of forces due to crane loads, vibration, impact, shrinkage, temperature changes, creep, expansion of shrinkage-compensating concrete, and unequal settlement of supports shall be duly considered.
### 6.1.4 Methods of Analysis
#### 6.1.4.1
Members of frames or continuous construction (beams or one-way slabs) shall be designed for the maximum effects of factored loads as determined by the theory of elastic analysis, except as modified for redistribution of moments in continuous flexural members according to Sec 6.1.5. Design is permitted to be simplified by using the assumptions specified in Sections 6.1.6, 6.1.9 to 6.1.12.
#### 6.1.4.2
Frame analysis by approximate methods shall be permitted for buildings of usual types of construction, spans, and story heights.
#### 6.1.4.3
Provided (a) to (e) below are satisfied, the approximate moments and shears given here shall be permitted for design of continuous beams and oneway slabs (slabs reinforced to resist flexural stresses in only one direction), as an alternate to frame analysis:
* (a) There are two or more spans;
* (b) Spans are approximately equal, with the larger of two adjacent spans not greater than the shorter by more than 20 percent;
* (c) Loads are uniformly distributed;
* (d) Unfactored live load, $L$, does not exceed three times unfactored dead load, $D$; and
* (e) Members are prismatic.
For calculating negative moments, $\ell_n$ is taken as the average of the adjacent clear span lengths.
Positive moment
| End spans | |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------- |
| Discontinuous end unrestrained | $\frac{w_u \ell_n^2}{11}$ |
| Discontinuous end integral with support | $\frac{w_u \ell_n^2}{14}$ |
| Interior spans | $\frac{w_u \ell_n^2}{16}$ |
| Negative moments at exterior face of first interior support
Two spans | $\frac{w_u \ell_n^2}{9}$ |
| More than two spans | $\frac{w_u \ell_n^2}{10}$ |
| Negative moment at other faces of interior supports | $\frac{w_u \ell_n^2}{11}$ |
| Negative moment at face of all supports for Slabs with spans not exceeding 3 m; and beams where ratio of sum of column stiffnesses to beam stiffness exceeds 8 at each end of the span | $\frac{w_u \ell_n^2}{12}$ |
| Negative moment at interior face of exterior support for members built integrally with supports
Where support is spandrel beam | $\frac{w_u \ell_n^2}{24}$ |
| Where support is a column | $\frac{w_u \ell_n^2}{16}$ |
| Shear in end members at face of first interior support | $\frac{1.15 w_u \ell_n}{2}$ |
| Shear at face of all other supports | $\frac{w_u \ell_n}{2}$ |
#### 6.1.4.4
Strut-and-tie models, provided in Appendix I, shall be permitted to be used in the design of structural concrete.
### 6.1.5 Redistribution of Moments in Continuous Flexural Members
#### 6.1.5.1
It shall be permitted to decrease factored moments calculated by elastic theory at sections of maximum negative or maximum positive moment in any span of continuous flexural members for any assumed loading arrangement by not more than $1000\varepsilon_t$ percent, with a maximum of 20 percent, except where approximate values for moments are used.
#### 6.1.5.2
Redistribution of moments shall be made only when $\varepsilon_t$ is equal to or greater than 0.0075 at the section at which moment is reduced.
#### 6.1.5.3
At all other sections within the spans, the reduced moment shall be used for calculating redistributed moments. Static equilibrium shall have to be maintained after redistribution of moments for each loading arrangement.
### 6.1.6 Span Length
#### 6.1.6.1
The span length of a simply supported beam shall be taken as the smaller of the distance between the centres of bearings, or the clear distance between supports plus the effective depth.
#### 6.1.6.2
For determination of moments in analysis of frames or continuous construction, span length shall be taken as the distance center-to-center of supports.
#### 6.1.6.3
Design on the basis of moments at faces of support shall be permitted for beams built integrally with supports.
#### 6.1.6.4
It shall be permitted to analyze solid or ribbed slabs built integrally with supports, with clear spans not more than 3 m, as continuous slabs on knife edge supports with spans equal to the clear spans of the slab and width of beams otherwise neglected.
#### 6.1.6.5
The effective length of a cantilever is its length to the face of the support plus half its effective depth, except where it forms the end of a continuous beam, where the length to the centre of support shall be used.
### 6.1.7 Modulus of Elasticity
#### 6.1.7.1
Modulus of elasticity, $E_c$, for concrete shall be permitted to be taken as $w_c^{1.5}$, $0.043\sqrt{f_c'}$ (in MPa) for values of $w_c$ between 1440 and 2560 kg/m3 . For normal weight concrete, $E_c$ shall be permitted to be taken as $4700\sqrt{f_c'}$ (in MPa).
#### 6.1.7.2
Modulus of elasticity, $E_s$, for reinforcement shall be permitted to be taken as 200,000 MPa.
### 6.1.8 Lightweight Concrete
#### 6.1.8.1
To account for the use of lightweight concrete, unless specifically noted otherwise, a modification factor $\lambda$ appears as a multiplier of $\sqrt{f_c'}$ in all applicable equations and sections of this Code, where, $\lambda$ = 0.85 for sand-lightweight concrete and 0.75 for all-lightweight concrete. Linear interpolation between 0.75 and 0.85 shall be permitted, on the basis of volumetric fractions, when a portion of the lightweight fine aggregate is replaced with normal weight fine aggregate. Linear interpolation between 0.85 and 1.0 shall be permitted, on the basis of volumetric fractions, for concrete containing normal weight fine aggregate and a blend of lightweight and normal weight coarse aggregates. For normal weight concrete, $\lambda$ = 1.0. If average splitting tensile strength of lightweight concrete, $f_{ct}$, is specified, $\lambda = \frac{f_{ct}}{1.8\sqrt{f_c'}} \leq 1.0$.
### 6.1.9 Stiffness
#### 6.1.9.1
For computing relative flexural and torsional stiffnesses of columns, walls, floors, and roof systems, use of any set of reasonable assumptions shall be permitted. The assumptions adopted shall be consistent throughout analysis.
#### 6.1.9.2
Both in determining moments and in design of members, effect of haunches shall be considered.
### **6.1.10 Effective Stiffness for Determining Lateral Deflections**
#### 6.1.10.1
Lateral deflections resulting from service lateral loads for reinforced concrete building systems shall be computed by either a linear analysis with member stiffness determined using 1.4 times the flexural stiffness defined in Sections 6.1.11.2 and 6.1.11.3 or by a more detailed analysis. Member properties shall not be taken greater than the gross section properties.
#### 6.1.10.2
Lateral deflections resulting from factored lateral loads for reinforced concrete building systems shall be computed either by linear analysis with member stiffness defined by (a) or (b), or by a more detailed analysis considering the reduced stiffness of all members under the loading conditions:
* (a) By section properties defined in Sec 6.3.10.4.1(a) to (c); or
* (b) 50 percent of stiffness values based on gross section properties.
#### 6.1.10.3
Lateral deflections resulting from factored lateral loads shall be permitted to be computed by using linear analysis, where two-way slabs without beams are designated as part of the seismic-force-resisting system. The stiffness of slab members shall be defined by a model that is in substantial agreement with results of comprehensive tests and analysis and the stiffness of other frame members shall be as defined in Sec 6.1.11.2.
### **6.1.11 Considerations for Columns**
#### 6.1.11.1
Columns shall be designed to resist the axial forces from factored loads on all floors or roof and the maximum moment from factored loads on a single adjacent span of the floor or roof under consideration. Loading condition resulting the maximum ratio of moment to axial load shall also be considered.
#### 6.1.11.2
In frames or continuous construction, consideration shall be given to the effect of unbalanced floor or roof loads on both exterior and interior columns and of eccentric loading due to other causes.
#### 6.1.11.3
It shall be permitted to assume far ends of columns built integrally with the structure to be fixed, while computing gravity load moments in columns.
#### 6.1.11.4
Resistance to moments at any floor or roof level shall be provided by distributing the moment between columns immediately above and below the given floor in proportion to the relative column stiffnesses and conditions of restraint.
### 6.1.12 Live Load Arrangement
#### 6.1.12.1
The following shall be permitted to assume:
* (a) The live load is applied only to the floor or roof under consideration; and
* (b) The far ends of columns built integrally with the structure are considered to be fixed.
#### 6.1.12.2
Arrangement of live load shall be permitted to be assumed to be limited to combinations of:
* (a) Factored dead load on all spans with full factored live load on two adjacent spans; and
* (b) Factored dead load on all spans with full factored live load on alternate spans.
### 6.1.13 Construction of T-beam
#### 6.1.13.1
In the construction of T-beam, the flange and web shall be built integrally or otherwise effectively bonded together.
#### 6.1.13.2
Width of slab effective as a T-beam flange shall not exceed one-quarter of the span length of the beam, and the effective overhanging flange width on each side of the web shall not exceed:
* (a) Eight times the slab thickness; and
* (b) One-half the clear distance to the next web.
#### 6.1.13.3
The effective overhanging flange width for beams with a slab on one side only shall not exceed:
* (a) One-twelfth the span length of the beam;
* (b) Six times the slab thickness; and
* (c) One-half the clear distance to the next web.
#### 6.1.13.4
Isolated beams, in which the T-shape is used to provide a flange for additional compression area, shall have a flange thickness not less than one-half the width of web and an effective flange width not more than four times the width of web.
#### 6.1.13.5
When primary flexural reinforcement in a slab that is considered as a T-beam flange (excluding joist construction) is parallel to the beam, reinforcement shall be provided in the top of the slab in the direction perpendicular to the beam and in accordance with the following:
##### 6.1.13.5.1
Transverse reinforcement shall be designed to carry the factored load on the overhanging slab width assumed to act as a cantilever. For isolated beams, the full width of overhanging flange shall be considered. For other T- beams, only the effective overhanging slab width need be considered.
##### 6.1.13.5.2
Spacing of transverse reinforcement shall be not farther apart than five times the slab thickness, nor farther apart than 450 mm.
### 6.1.14 Construction of Joist
#### 6.1.14.1
Construction of joist consists of a monolithic combination of regularly spaced ribs and a top slab arranged to span in one direction or two orthogonal directions.
#### 6.1.14.2
Width of ribs shall not be less than 100 mm, and the ribs shall have a depth of not more than 3.5 times the minimum width of rib.
#### 6.1.14.3
Clear spacing between ribs shall not exceed 750 mm.
#### 6.1.14.4
Joist construction not meeting the limitations of Sections 6.1.15.1 to 6.1.15.3 shall be designed as slabs and beams.
#### 6.1.14.5
When permanent burned clay or concrete tile fillers of material having a unit compressive strength at least equal to r in the joists are used:
##### 6.1.14.5.1
For shear and negative moment strength computations, the vertical shells of fillers in contact with the ribs shall be permitted to include. Other portions of fillers shall not be included in strength computations.
##### 6.1.14.5.2
Slab thickness over permanent fillers shall be not less than 1/12th the clear distance between ribs, nor less than 40 mm.
##### 6.1.14.5.3
Reinforcement normal to the ribs shall be provided in the in oneway joists, as required by Sec 8.1.11
#### 6.1.14.6
When removable forms or fillers are used, which do not comply with Sec 6.1.15.5, then:
##### 6.1.14.6.1
Slab thickness shall be not less than 1/12th the clear distance between ribs, nor less than 50 mm.
##### 6.1.14.6.2
Reinforcement normal to the ribs shall be provided in the slab as required for flexure, considering load concentrations, if any, but not less than required by Sec 8.1.11
#### 6.1.14.7
Where conduits or pipes as permitted by relevant provisions of embedments in concrete are embedded within the slab, slab thickness shall be at least 25 mm greater than the total overall depth of the conduits or pipes at any point. Conduits or pipes shall not impair significantly the strength of the construction.
#### 6.1.14.8
For joist construction, \phi shall be permitted to be 10 percent more than that specified in Sec 6.4.
### 6.1.15 Separate Floor Finish
#### 6.1.15.1
Unless placed monolithically with the floor slab or designed in accordance with requirements of Sec. 6.12, floor finish shall not be included as part of a structural member.
#### 6.1.15.2
All concrete floor finishes shall be permitted to be considered as part of required cover or total thickness for nonstructural considerations.
## 6.2 Strength and Serviceability Requirements
### 6.2.1 General
#### 6.2.1.1
Structures and structural members shall be designed to have design strengths at all sections at least equal to the required strengths calculated for the factored loads and forces in such combinations as are stipulated in this Code.
#### 6.2.1.2
Members also shall meet all other requirements of this Code to ensure adequate performance at service load levels.
### 6.2.2 Required Strength
#### 6.2.2.1
Required strength $U$ shall be at least equal to the effects of factored loads in such combinations as are stipulated in Chapter 2, Loads.
#### 6.2.2.2
If resistance to impact effects is taken into account in design, such effects shall be included with $L$.
#### 6.2.2.3
Estimations of differential settlement, creep, shrinkage, expansion of shrinkage-compensating concrete, or temperature change shall be based on a realistic assessment of such effects occurring in service.
#### 6.2.2.4
For structures like emergency preparedness centre, cyclone shelters etc. in coastal zone, in load combination 4 of Sec 2.7.3.1 of Chapter 2, the coefficient of live load L shall be taken 1.6 instead of 1.0.
### 6.2.3 Design Strength
#### 6.2.3.1
Design strength provided by a member, and its connections to other members, in terms of flexure, axial load, shear, and torsion, shall be taken as the nominal strength calculated in accordance with the requirements and assumptions of this Chapter, multiplied by a strength reduction factors $\phi$ as stipulated in Sections 6.2.3.2 to 6.2.3.4.
#### 6.2.3.2
Strength reduction factor $\phi$ is given in Sections 6.2.3.2.1 to 6.2.3.2.6:
##### 6.2.3.2.1
For tension-controlled sections as defined in Sec 6.3.3.4: 0.90
##### 6.2.3.2.2
For compression-controlled sections, as defined in Sec 6.3.3.3:
|Members with spiral reinforcement conforming to Sec 6.3.9.3:|0.75|
|Other reinforced members:|0.65|
For sections in which the net tensile strain in the extreme tension steel at nominal strength, $\varepsilon_t$, is between the limits for compression-controlled and tension-controlled sections, $\phi$ shall be permitted to be linearly increased from that for compression-controlled sections to 0.90 as $\varepsilon_t$ increases from the compression controlled strain limit to 0.005 (Also see Figure 6.6.1). While interpolating, it shall be permitted to round $\phi$ to second digit after decimal.
##### 6.2.3.2.3
It shall be permitted for compression-controlled sections, as defined in Sec 6.3.3.3, the following optional, more conservative alternative values of strength reduction factor $\phi$, where less controlled construction environment justifies such selection according to engineering judgment of the designer:
For members with spiral reinforcement conforming to Sec 6.3.9.3:0.70
For other reinforced members: 0.60
For sections in which the net tensile strain in the extreme tension steel at nominal strength, $\varepsilon_t$, is between the limits for compression-controlled and tension-controlled sections, $\phi$ shall be permitted to be linearly increased from that for compression-controlled sections to 0.90 as $\varepsilon_t$ increases from the compression controlled strain limit to 0.005 (Also see Figure 6.6.2). While interpolating, it shall be permitted to round $\phi$ to second digit after decimal.
![Variation of strength reduction factor phi with net tensile strain in extreme tension steel and c/dt for Grade 420 reinforcement and prestressing steel]()
##### 6.2.3.2.4
Strength reduction factor for shear and torsion: 0.75
##### 6.2.3.2.5
Strength reduction factor for bearing on concrete (except for posttensioned anchorage zones and strut-and-tie models): 0.65
##### 6.2.3.2.6
Strength reduction factor for strut-and-tie models (Appendix I), and struts, ties, nodal zones, and bearing areas in such models: 0.75
##### 6.2.3.2.7
Calculation of development length specified in Sec 8.2 does not require strength reduction factor $\phi$.
#### 6.2.3.3
For structures relying on intermediate precast structural walls in Seismic Design Category D, special moment frames, or special structural walls to resist earthquake effects, $E$, $\phi$ shall be modified as given in (a) through (c):
* (a) For any structural member that is designed to resist $E$, if the nominal shear strength of the member is less than the shear corresponding to the development of the nominal flexural strength of the member, $\phi$ for shear shall be 0.60. The nominal flexural strength shall be determined considering the most critical factored axial loads and including $E$;
* (b) For diaphragms, $\phi$ for shear shall not exceed the minimum $\phi$ for shear used for the vertical components of the primary seismic-forceresisting system;
* (c) For joints and diagonally reinforced coupling beams, $\phi$ for shear shall be 0.85.
#### 6.2.3.4
Strength reduction factor $\phi$ shall be 0.60 for flexure, compression, shear, and bearing of structural plain concrete.
### 6.2.4 Design Strength for Reinforcement
The values of $f_y$ and $f_{yt}$ used in design calculations shall not exceed 550 MPa, except for transverse reinforcement in Sections 6.3.9.3 and 8.3.
![Variation of strength reduction factor phi with net tensile strain and c/dt for Grade 420 reinforcement and prestressing steel with reduced phi values for compression controlled sections]()
### 6.2.5 Control of Deflections
#### 6.2.5.1
Reinforced concrete members subjected to flexure shall be designed to have adequate stiffness to limit deflections or any deformations that may adversely affect strength or serviceability of a structure.
#### 6.2.5.2 One-way construction (non prestressed)
##### 6.2.5.2.1
Minimum thickness stipulated in Table 6.6.1 shall apply for one-way construction not supporting or attached to partitions or other construction likely to be damaged by large deflections, unless computation of deflection indicates a lesser thickness can be used without adverse effects.
##### 6.2.5.2.2
Where deflections are to be computed, deflections that occur immediately on application of load shall be computed by usual methods or formulas for elastic deflections, considering effects of cracking and reinforcement on member stiffness.
##### 6.2.5.2.3
If not stiffness values are obtained by a more comprehensive analysis, immediate deflection shall be computed with the modulus of elasticity for concrete, $E_c$, as specified in 6.1.7.1 (normal weight or lightweight concrete) and with the effective moment of inertia, $I_e$, as follows, but not greater than $I_g$
$$
I_e = \left(\frac{M_{cr}}{M_a}\right)^3I_g + \left[1-\left(\frac{M_{cr}}{M_a}\right)^3\right]I_{cr} \tag{6.6.1}
$$
Where,
$$
M_{cr} = \frac{f_rI_g}{y_t} \tag{6.6.2}
$$
And,
$$
f_r = 0.62\lambda\sqrt{f_c'} \tag{6.6.3}
$$
Table 6.6.1: Minimum Thickness of Non prestressed beams or one-Way slabs Unless Deflections are calculated
| Member | Simply
supported | One end
continuous | Both ends
continuous | Cantilever |
| ------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------- | ----------------------- | ------------------------- | ---------- |
| Minimum thickness, $h$, for members not supporting or attached to partitions or other
construction likely to be damaged by large deflections | | | | |
| Solid one-way slabs | $l/20$ | $l/24$ | $l/28$ | $l/10$ |
| Beams or ribbed one-way slabs | $l/16$ | $l/18.5$ | $l/21$ | $l/8$ |
Notes:
Values given shall be used directly for members with normal weight concrete and Grade 420 reinforcement. For other conditions, the values shall be modified as follows:
* (a) For lightweight concrete having equilibrium density, $w_c$, in the range of 1440 to 1840 kg/m3, the values shall be multiplied by $(1.65 - 0.0003w_c)$ but not less than 1.09.
* (b) For $f_y$ other than 420MPa, the values shall be multiplied by $(0.4 + f_y/700)$.
##### 6.2.5.2.4
*Ie* shall be permitted to be taken for continuous members as the average of values obtained from Eq. 6.6.1 for the critical positive and negative moment sections. For prismatic members, *Ie* shall be permitted to be taken as the value obtained from Eq. 6.6.1 at mid span for simple and continuous spans, and at support for cantilevers.
##### 6.2.5.2.5
If the values are not obtained by a more comprehensive analysis, additional long-term deflection resulting from creep and shrinkage of flexural members (normal weight or lightweight concrete) shall be determined by multiplying the immediate deflection caused by the sustained load considered, by the factor ∆
Where, r shall be the value at midspan for simple and continuous spans, and at support for cantilevers. It shall be permitted to assume $\xi$, the time-dependent factor for sustained loads, to be equal to:
| 5 years or more | 2.0 |
| --------------- | --- |
| 12 months | 1.4 |
| 6 months | 1.2 |
| 3 months | 1.0 |
##### 6.2.5.2.6
The value of deflection computed in accordance with Sections 6.2.5.2.2 to 6.2.5.2.5 shall not exceed limits stipulated in Table 6.6.2.
#### 6.2.5.3 Two-way construction (non prestressed)
##### 6.2.5.3.1
The minimum thickness of slabs or other two-way construction designed in accordance with the provisions of Sec. 6.5 and conforming to the requirements of Sec 6.5.6.1.2 shall be governed by Sec 6.2.5.3. The thickness of slabs without interior beams spanning between the supports on all sides shall satisfy the requirements of Sec 6.2.5.3.2 or Sec 6.2.5.3.4. The thickness of slabs with beams spanning between the supports on all sides shall satisfy requirements of Sec 6.2.5.3.3 or Sec 6.2.5.3.4.
##### 6.2.5.3.2
If slabs are without interior beams spanning between the supports and have a ratio of long to short span not greater than 2, the minimum thickness shall be in accordance with the provisions of Table 6.6.3 and shall not be less than the following values:
Slabs without drop panels as defined in Sec 6.5.2.5: 125 mm
Slabs with drop panels as defined in Sec 6.5.2.5: 100 mm
Table 6.6.2: Maximum Allowable Computed Deflections
| Type of member | Deflection to be considered | Deflection
limitation |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------- |
| Flat roofs not supporting or attached
to nonstructural elements likely to be
damaged by large deflections | Immediate deflection due to | $\ell/180$\* |
| Floors not supporting or attached to
nonstructural elements likely to be
damaged by large deflections | live load $L$ | $\ell/360$ |
| Roof or floor construction supporting
or attached to nonstructural elements
likely
to
be
damaged
by
large
deflections | That part of the total deflection
occurring after attachment of
nonstructural elements (sum of
the long-term deflection due to | $\ell/480$‡ |
| Roof or floor construction supporting
or attached to nonstructural elements
not likely to be damaged by large
deflections | all sustained loads and the
immediate deflection due to
any additional live load)† | $\ell/240$§ |
| \* Limit not intended to safeguard against ponding. Ponding should be checked by suitable calculations of deflection, including added deflections due to ponded water, and considering long-term effects of all sustained loads, camber, construction tolerances, and reliability of provisions for drainage. | | |
† Long-term deflection shall be determined in accordance with Sec 6.2.5.2.5, but may be reduced by amount of deflection calculated to occur before attachment of nonstructural elements. This amount shall be determined on basis of accepted engineering data relating to time-deflection characteristics of members similar to those being considered.
‡ Limit may be exceeded if adequate measures are taken to prevent damage to supported or attached elements.
§ Limit shall not be greater than tolerance provided for nonstructural elements. Limit may be exceeded if camber is provided so that total deflection minus camber does not exceed limit.
Table 6.6.3: Minimum Thickness of Slabs without Interior Beams\*
| | Witho | ut drop pan | els$l$ | W | ith drop pa | nels$l$ |
| ----------------------------- | ----------------------- | -------------------------------------- | ----------------- | ----------------------- | -------------------------------------- | ------------------ |
| $f_y$, MPa\beta\_t | Exterior | panels | Interior | Exterior | panels | Interior panels |
| | Without
edge beams |
With edge
beams§ | panels | Without
edge beams |
With edge
beams§ | |
| 280 | $\ell_n/33$ | $\ell_n/36$ | $\ell_n/36$ | $\ell_n/36$ | $\ell_n/40$ | $\ell_n/40$ |
| 420 | $\ell_n/30$ | $\ell_n/33$ | $\ell_n/33$ | $\ell_n/33$ | $\ell_n/36$ | $\ell_n/36$ |
| 520 | $\ell_n/28$ | $\ell_n/31$ | $\ell_n/31$ | $\ell_n/31$ | $\ell_n/34$ | $\ell_n/34$ |
* For two-way construction, $\ell_n$ is the length of clear span in the long direction, measured face-to-face of supports in slabs without beams and face-to-face of beams or other supports in other cases.
* For $f_y$ between the values given in the table, minimum thickness shall be determined by linear interpolation.
* Drop panels as defined in Sec 6.5.2.5.
* § Slabs with beams between columns along exterior edges. The value of $\alpha_f$ for the edge beam shall not be less than 0.8.
##### 6.2.5.3.3
The minimum thickness, *h* for slabs with beams spanning between the supports on all sides, shall be as follows:
* (a) For $\alpha_{fm}$ equal to or less than 0.2, the provisions of Sec 6.2.5.3.2 shall apply;
* (b) For $\alpha_{fm}$ greater than 0.2 but not greater than 2.0, $h$ shall not be less than
$$
h = \frac{\ell_n(0.8 + f_y/1400)}{36 + 5\beta(\alpha_{fm} - 0.2)} \geq 125 \text{ mm} \tag{6.6.5}
$$
(c) For $\alpha_{fm}$ greater than 2.0, $h$ shall not be less than
$$
h = \frac{\ell_n(0.8 + f_y/1400)}{36 + 9\beta} \geq 90 \text{ mm} \tag{6.6.6}
$$
(d) An edge beam with a stiffness ratio $\alpha_f$ not less than 0.80 shall be provided at discontinuous edges, or the minimum thickness required by Eq. 6.6.5 or Eq. 6.6.6 shall be increased by at least 10 percent in the panel with a discontinuous edge.
Term $\ell_n$ in (b) and (c) is length of clear span in long direction measured face-to-face of beams. Term $\beta$ in (b) and (c) is ratio of clear spans in long to short direction of slab.
##### 6.2.5.3.4
When computed deflections do not exceed the limits of Table 6.6.2, slab thickness less than the minimum required by Sections 6.2.5.3.1 to 6.2.5.3.3 shall be permitted. Deflections shall be computed taking into account size and shape of the panel, conditions of support, and nature of restraints at the panel edges. The modulus of elasticity of concrete, *Ec* , shall be as specified in Sec 6.1.7.1. The effective moment of inertia,*I* *e*, shall be that given by Eq. 6.6.1; other values shall be permitted to be used if they result in computed deflections in reasonable agreement with results of comprehensive tests. Additional long-term deflection shall be computed in accordance with Sec 6.2.5.2.5.
#### 6.2.5.4 Composite construction
##### 6.2.5.4.1 Shored construction
Where composite flexural members are supported during construction so that, after removal of temporary supports, dead load is resisted by the full composite section, it shall be permitted to consider the composite member equivalent to a monolithically cast member for computation of deflection. For non prestressed members, the portion of the member in compression shall determine whether values in Table 6.6.1 for normal weight or lightweight concrete shall apply. If deflection is computed, account shall be taken of curvatures resulting from differential shrinkage of precast and castin-place components, and of axial creep effects in a prestressed concrete member.
##### 6.2.5.4.2 Unshored construction
When the thickness of a non prestressed precast flexural member meets the requirements of Table 6.6.1, deflection need not be computed. If the thickness of a non prestressed composite member meets the requirements of Table 6.6.1, it is not required to compute deflection occurring after the member becomes composite, but the long-term deflection of the precast member shall be investigated for magnitude and duration of load prior to beginning of effective composite action.
##### 6.2.5.4.3
The computed deflection in accordance with Sec 6.2.5.4.1 or Sec 6.2.5.4.2 shall not exceed limits stipulated in Table 6.6.2.
## **6.3 Axial Loads and Flexure**
### **6.3.1 Scope**
The provisions of Sec. 6.3 shall be applicable to the design of members subject to flexure or axial loads or a combination thereof.
### **6.3.2 Design Assumptions**
#### 6.3.2.1
The assumptions given in Sections 6.3.2.2 to 6.3.2.7, and satisfaction of applicable conditions of equilibrium and compatibility of strains shall form the basis of strength design of members for flexure and axial loads.
#### 6.3.2.2
The strains in reinforcement and concrete hall be assumed to be directly proportional to the distance from the neutral axis, except that, for deep beams as defined in Sec 6.3.7.1, an analysis that considers a nonlinear distribution of strain shall be used. Alternatively, it shall be permitted to use a strut-and-tie model. See Sections 6.3.7, 6.4.6, and Appendix I.
#### 6.3.2.3
The maximum usable strain at extreme concrete compression fiber shall be assumed to be 0.003.
#### 6.3.2.4
For stress in reinforcement below , it shall be taken as times steel strain. For strains greater than that corresponding to , stress in reinforcement shall be considered independent of strain and equal to .
#### 6.3.2.5
In axial and flexural calculations of reinforced concrete, the tensile strength of concrete shall be neglected.
#### 6.3.2.6
The relationship between concrete compressive stress distribution and concrete strain shall be assumed to be rectangular, trapezoidal, parabolic, or any other shape that results in prediction of strength in substantial agreement with results of comprehensive tests.
#### 6.3.2.7
An equivalent rectangular concrete stress distribution defined by Sections 6.3.2.7.1 to 6.3.2.7.3 below shall satisfy the requirements of Sec 6.3.2.6.
##### 6.3.2.7.1
Concrete stress of $0.85f_c'$ shall be assumed uniformly distributed over an equivalent compression zone bounded by edges of the cross section and a straight line located parallel to the neutral axis at a distance $a = \beta_1c$ from the fibre of maximum compressive strain.
##### 6.3.2.7.2
Distance from the fibre of maximum strain to the neutral axis, $c$, shall be measured in a direction perpendicular to the neutral axis.
##### 6.3.2.7.3
For $f_c'$ between 17 and 28 MPa, $\beta_1$ shall be taken as 0.85. For $f_c'$ above 28 MPa, $\beta_1$ shall be reduced linearly at a rate of 0.05 for each 7 MPa of strength in excess of 28 MPa, but $\beta_1$ shall not be taken less than 0.65. For $f_c'$ between 28 and 56 MPa, $\beta_1$ may be calculated from Eq. 6.6.7.
$$
\beta_1 = 0.85 - 0.007143(f_c' - 28) \text{ and } 0.65 \leq \beta_1 \leq 0.85 \tag{6.6.7}
$$
### **6.3.3 General Principles and Requirements**
#### 6.3.3.1
Stress and strain compatibility using assumptions in Sec 6.3.2 shall be the basis for design of cross sections subject to flexure or axial loads, or a combination thereof.
#### 6.3.3.2
A cross section shall be considered to be in balanced strain conditions when the tension reinforcement reaches the strain corresponding to $f_y$ just as concrete in compression reaches its assumed ultimate strain of 0.003.
#### 6.3.3.3
Sections are compression-controlled if the net tensile strain in the extreme tension steel, , is equal to or less than the compression-controlled strain limit when the concrete in compression reaches its assumed strain limit of 0.003, Figure 6.6.3. The compression-controlled strain limit is the net tensile strain in the reinforcement at balanced strain conditions. For Grade 420 reinforcement, it shall be permitted to set the compression-controlled strain limit equal to 0.002. For other grades compression-controlled strain limit may be determined by dividing the yield strength by modulus of elasticity E and then rounding the value obtained to four significant digits after the decimal. For example, for Grade 500 reinforcement, the compressioncontrolled strain limit shall equal to 0.0025.
![Strain distribution and net tensile strain in reinforced concrete flexural member]()
#### 6.3.3.4
Sections are tension-controlled if the net tensile strain in the extreme tension steel, , is equal to or greater than 0.005 when the concrete in compression reaches its assumed strain limit of 0.003. Sections with between the compressioncontrolled strain limit and 0.005 constitute a transition region between compressioncontrolled and tension-controlled sections.
#### 6.3.3.5
Net tensile strain in the extreme tension steel at nominal strength, $\varepsilon_t$ shall not be less than 0.004 for non prestressed flexural members and non prestressed members with factored axial compressive load less than $0.10f_c'A_g$.
##### 6.3.3.5.1
Use of compression reinforcement shall be permitted in conjunction with additional tension reinforcement to increase the strength of flexural members.
#### 6.3.3.6
For compression members, design axial strength $\phi P_n$ shall not be taken greater than $\phi P_{n,max}$, computed by Eq. 6.6.8 or Eq. 6.6.9.
##### 6.3.3.6.1
For non prestressed members with spiral reinforcement conforming to Sec. 8.1 or composite members conforming to 6.3.13:
$$
\phi P_{n,max} = 0.85\phi\left[0.85f_c'(A_g - A_{st}) + f_yA_{st}\right] \tag{6.6.8}
$$
##### 6.3.3.6.2
For non prestressed members with tie reinforcement conforming to Sec. 8.1:
$$
\phi P_{n,max} = 0.80\phi\left[0.85f_c'(A_g - A_{st}) + f_yA_{st}\right] \tag{6.6.9}
$$
#### 6.3.3.7
Members subject to compressive axial load shall be designed for the maximum moment that can accompany the axial load. The factored axial force $P_u$ at given eccentricity shall not exceed the value that given in Sec 6.3.3.6. The maximum factored moment $M_u$ shall be magnified for slenderness effects in accordance with Sec 6.3.10.
### **6.3.4 Spacing of Lateral Supports for Flexural Members**
#### 6.3.4.1
Distance between lateral supports for a beam shall not exceed 50 times $b$, the least width of compression flange or face.
#### 6.3.4.2
Effects of lateral eccentricity of load shall be taken into account in determining spacing of lateral supports.
### **6.3.5 Minimum Reinforcement for Members in Flexure**
#### 6.3.5.1
At every section of a flexural member where tensile reinforcement is required by analysis, except as provided in Sections 6.3.5.2 to 6.3.5.4, $A_s$ provided shall not be less than that given by Equations 6.6.10a and 6.6.10b.
$$
A_{s,min} = \frac{0.25\sqrt{f_c'}}{f_y}b_wd \tag{6.6.10a}
$$
$$
A_{s,min} = \frac{1.4b_wd}{f_y} \tag{6.6.10b}
$$
#### 6.3.5.2
For statically determinate members with a flange in tension, $A_{s,min}$ shall not be less than the value given by Equations 6.6.10, except that $b_w$ is replaced by either $2b_w$ or the width of flange, whichever is smaller.
#### 6.3.5.3
If, at every section, $A_s$ provided is at least one-third greater than that required by analysis, the requirements of Sections 6.3.5.1 and 6.3.5.2 need not be applied.
#### 6.3.5.4
For structural slabs and footings including raft that help support the structure vertically of uniform thickness, $A_{s,min}$ in the direction of the span shall be the same as that required by Sec 8.1.11. Maximum spacing of this reinforcement shall not exceed three times the thickness, nor 450 mm.
### **6.3.6 Distribution of Flexural Reinforcement in One-Way Slabs and Beams**
#### 6.3.6.1
Rules for distribution of flexural reinforcement to control flexural cracking in beams and in one-way slabs (slabs reinforced to resist flexural stresses in only one direction) are prescribed in this section.
#### 6.3.6.2
Distribution of flexural reinforcement in two-way slabs shall be as required by Sec 6.5.3.
#### 6.3.6.3
As stated in Sec 6.3.6.4, flexural tension reinforcement shall be well distributed within maximum flexural tension zones of a member cross section.
#### 6.3.6.4
The spacing of reinforcement closest to the tension face, $s$, shall be less than that given by
$$
s = 380\left(\frac{280}{f_s}\right) - 2.5c_c \tag{6.6.11}
$$
But, shall not exceed, $300\left(\frac{280}{f_s}\right)$ where, $c_c$ is the least distance from surface of reinforcement to the tension face. If there is only one bar or wire nearest to the extreme tension face, $s$ used in Eq. 6.6.11 is the width of the extreme tension face.
Calculated stress $f_s$ in reinforcement closest to the tension face at service load shall be computed based on the unfactored moment. It shall be permitted to take $f_s$ as $\frac{2}{3}f_y$.
#### 6.3.6.5
For structures subject to very aggressive exposure or designed to be watertight, provisions of Sec 6.3.6.4 are not sufficient. For such structures, special investigations and precautions are required.
#### 6.3.6.6
When flanges of T-beam construction are in tension, part of the flexural tension reinforcement shall be distributed over an effective flange width as defined in Sec 6.1.13, or a width equal to one-tenth the span, whichever is smaller. If the effective flange width exceeds one-tenth the span, some longitudinal reinforcement shall be provided in the outer portions of the flange.
#### 6.3.6.7
Longitudinal skin reinforcement shall be uniformly distributed along both side faces of a member (Figure 6.6.4), where $h$ of a beam or joist exceeds 900 mm. Skin reinforcement shall extend for a distance $h/2$ from the tension face. The spacing $s$ shall be as provided in Sec 6.3.6.4, where $c_c$ is the least distance from the surface of the skin reinforcement to the side face. It shall be permitted to include such reinforcement in strength computations if a strain compatibility analysis is made to determine stress in the individual bars or wires.
![Skin reinforcement for beams and joists with height greater than 900 mm]()
### **6.3.7 Deep Beams**
#### 6.3.7.1
Deep beams are members loaded on one face and supported on the opposite face so that compression struts can develop between the loads and the supports, and have either:
* (a) Clear spans, $\ell_n$, equal to or less than four times the overall member depth; or
* (b) Regions with concentrated loads within twice the member depth from the face of the support.
Deep beams shall be designed either taking into account nonlinear distribution of strain, or by Appendix I. (See also Sections 6.4.6.1 and 8.2.7.6) Lateral buckling shall be considered.
#### 6.3.7.2
$V_n$ of deep beams shall be in accordance with Sec 6.4.6.
#### 6.3.7.3
Minimum area of flexural tension reinforcement, $A_{s,min}$, shall conform to Sec 6.3.5.
#### 6.3.7.4
Minimum horizontal and vertical reinforcement in the side faces of deep beams shall satisfy either Sec I.3.3 or Sec 6.4.6.4 and Sec 6.4.6.5.
### **6.3.8 Design Dimensions for Compression Members**
#### 6.3.8.1 Isolated compression member with multiple spirals
Outer limits of the effective cross section of a compression member with two or more interlocking spirals shall be taken at a distance outside the extreme limits of the spirals equal to the minimum concrete cover required by Sec 8.1.7.
#### 6.3.8.2 Monolithically built compression member with wall
Outer limits of the effective cross section of a spirally reinforced or tied reinforced compression member built monolithically with a concrete wall or pier shall be taken not greater than 40 mm outside the spiral or tie reinforcement.
#### 6.3.8.3 Equivalent circular compression member replacing other shapes
In lieu of using the full gross area for design of a compression member with a square, octagonal, or other shaped cross section, it shall be permitted to use a circular section with a diameter equal to the least lateral dimension of the actual shape. Gross area considered, required percentage of reinforcement, and design strength shall be based on that circular section.
#### 6.3.8.4 Limits of section
For a compression member with a cross section larger than required by considerations of loading, it shall be permitted to base the minimum reinforcement and strength on a reduced effective area $A_g$ not less than one-half the total area. This provision shall not apply to special moment frames or special structural walls designed in accordance with Sec. 8.3.
### **6.3.9 Limits of Reinforcement for Compression Members**
#### 6.3.9.1
For noncomposite compression members, the area of longitudinal reinforcement, $A_{st}$, shall be not less than $0.01A_g$ or more than $0.06A_g$. To avoid practical difficulties in placing and compacting of concrete as well as to deliver ductility to noncomposite compression members, area of longitudinal reinforcement, $A_{st}$, is preferred not to exceed $0.04A_g$ unless absolutely essential.
#### 6.3.9.2
Minimum number of longitudinal bars in compression members shall be 4 for bars within rectangular or circular ties, 3 for bars within triangular ties, and 6 for bars enclosed by spirals conforming to Sec 6.3.9.3.
#### 6.3.9.3
Volumetric spiral reinforcement ratio, $\rho_s$, shall be not less than the value given by
$$
\rho_s = 0.45\left(\frac{A_g}{A_{ch}} - 1\right)\frac{f_c'}{f_{yt}} \tag{6.6.12}
$$
Where the value of $f_{yt}$ used in Eq. 6.6.12 shall not exceed 700 MPa. For $f_{yt}$ greater than 420 MPa, lap splices according to 8.1.9.3(e) shall not be used.
### 6.3.10 Slenderness Effects in Compression Members
#### 6.3.10.1
Slenderness effects shall be permitted to be neglected in the following cases:
(a) for compression members not braced against side sway when:
$$
\frac{k\ell_u}{r} \leq 22 \tag{6.6.13}
$$
(b) for compression members braced against side sway when:
$$
\frac{k\ell_u}{r} \leq 34 - 12\frac{M_1}{M_2} \leq 40 \tag{6.6.14}
$$
Where, $M_1/M_2$ is positive if the column is bent in single curvature, and negative if the member is bent in double curvature.
Compression members may be considered to be braced against side sway when bracing elements have a total stiffness, resisting lateral movement of that story, of at least 12 times the gross stiffness of the columns within the story.
The Jackson and Moreland Alignment Charts (Figure 6.6.5), which allow a graphical determination of $k$ for a column of constant cross section in a multibay frame may be used as the primary design aid to estimate the effective length factor $k$.
$\Psi$ = ratio of $\Sigma (EI/\ell_c)$ of compression members to $\Sigma (EI/\ell)$ of flexural members in plane at one end of a compression member
$\ell$ = span length of flexural member measured center to center of joints
![Jackson and Moreland alignment charts for effective length factors k in non-sway and sway frames]()
##### 6.3.10.1.1
The unsupported length of a compression member,*l* *u* , shall be taken as the clear distance between floor slabs, beams, or other members capable of providing lateral support in the direction being considered. Where column capitals or haunches are present, *lu* shall be measured to the lower extremity of the capital or haunch in the plane considered.
##### 6.3.10.1.2
It shall be permitted to take the radius of gyration, *r* equal to 0.30 times the overall dimension in the direction stability is being considered for rectangular compression members and 0.25 times the diameter for circular compression members. For other shapes, it shall be permitted to compute *r* for gross concrete section.
#### 6.3.10.2
When slenderness effects are not neglected as permitted by Sec 6.3.10.1, the design of compression members, restraining beams, and other supporting members shall be based on the factored forces and moments from a second-order analysis satisfying Sec 6.3.10.3, Sec 6.3.10.4, or Sec 6.3.10.5. These members shall
also satisfy Sections 6.3.10.2.1 and 6.3.10.2.2. The dimensions of each member cross section used in the analysis shall be within 10 percent of the dimensions of the members shown on the design drawings or the analysis shall be repeated.
##### 6.3.10.2.1
Total moment including second-order effects in compression members, restraining beams, or other structural members shall not exceed 1.4 times the moment due to first-order effects.
##### 6.3.10.2.2
Second-order effects shall be considered along the length of compression members. It shall be permitted to account for these effects using the moment magnification procedure outlined in Sec 6.3.10.6.
#### 6.3.10.3 Nonlinear second-order analysis
Second-order analysis shall consider material nonlinearity, member curvature and lateral drift, duration of loads, shrinkage and creep, and interaction with the supporting foundation. The analysis procedure shall have been shown to result in prediction of strength in substantial agreement with results of comprehensive tests of columns in statically indeterminate reinforced concrete structures.
#### 6.3.10.4 Elastic second-order analysis
Elastic second-order analysis shall consider section properties determined taking into account the influence of axial loads, the presence of cracked regions along the length of the member, and the effects of load duration.
##### 6.3.10.4.1
It shall be permitted to use the following properties for the members in the structure:
(a) Modulus of elasticity, $E_c$ from Sec 6.1.7.1; (b) Moments of inertia, $I$ as follows; and (c) Area $1.0A_g$
| **Compression** | **Value of\*\*\*\**I*** | **Flexural members:** | **Value** |
| ----------------------------------------------------------------------------------------------------------------------------- | ----------------------- | -------------------------- | ----------------- |
| **members:** | | | **of\*\*\*\**I*** |
| Columns | $0.70I_g$ | Beams | $0.35I_g$ |
| Walls: | | Flat plates and flat slabs | $0.25I_g$ |
| Uncracked | $0.70I_g$ | | |
| Cracked | $0.35I_g$ | | |
| Alternatively, the moments of inertia of compression and flexural members, $I$, shall be permitted to be computed as follows: | | | |
(i) Compression members:
$$
I = \left[0.80 + 25\frac{A_{st}}{A_g}\right]\left(1 - \frac{M_u}{P_u h} - 0.5\frac{P_u}{P_o}\right) I_g \leq 0.875I_g \tag{6.6.15}
$$
Where, $P_u$ and $M_u$ shall be determined from the particular load combination under consideration, or the combination of $P_u$ and $M_u$ determined in the smallest value of $I$. The value of $I$ need not be taken less than $0.35I_g$.
(ii) Flexural members:
$$
I = (0.10 + 25\rho)\left(1.2 - 0.2\frac{b_w}{d}\right) I_g \leq 0.5I_g \tag{6.6.16}
$$
For continuous flexural members, $I$ shall be permitted to be taken as the average of values obtained from Eq. 6.6.16 for the critical positive and negative moment sections. The value of $I$ need not be taken less than $0.25I_g$. The cross-sectional dimensions and reinforcement ratio used in the above formulas shall be within 10 percent of the dimensions and reinforcement ratio shown on the design drawings or the stiffness evaluation shall be repeated.
##### 6.3.10.4.2
When sustained lateral loads are present, $I$ for compression members shall be divided by $(1 + \beta_{ds})$. The term $\beta_{ds}$ shall be taken as the ratio of maximum factored sustained shear within a story to the maximum factored shear in that story associated with the same load combination, but shall not be taken greater than 1.0.
#### 6.3.10.5 Procedure for moment magnification
Columns and stories in structures shall be designated as nonsway or sway columns or stories. The design of columns in nonsway frames or stories shall be based on Sec 6.3.10.6. The design of columns in sway frames or stories shall be based on Sec 6.3.10.7.
##### 6.3.10.5.1
A column in a structure shall be permitted to be assumed as nonsway if the increase in column end moments due to second-order effects does not exceed 5 percent of the first-order end moments.
##### 6.3.10.5.2
A story within a structure is permitted to be assumed as nonsway, if:
$$
Q = \frac{\Sigma P_u \Delta_o}{V_{us} \ell_c} \leq 0.05 \tag{6.6.17}
$$
Where $\Sigma P_u$ and $V_{us}$ are the total factored vertical load and the horizontal story shear, respectively, in the story being evaluated, and $\Delta_o$ is the first-order relative lateral deflection between the top and the bottom of that story due to $V_{us}$.
#### 6.3.10.6 Procedure for moment magnification - nonsway
Compression members shall be designed for factored axial force $P_u$ and the factored moment amplified for the effects of member curvature $M_c$ where
$$
M_c = \delta_{ns} M_2 \tag{6.6.18}
$$
Where,
$$
\delta_{ns} = \frac{C_m}{1 - \frac{P_u}{0.75P_c}} \geq 1.0 \tag{6.6.19}
$$
And,
$$
P_c = \frac{\pi^2 EI}{(k\ell_u)^2} \tag{6.6.20}
$$
##### 6.3.10.6.1
EI shall be taken as
$$
EI = \frac{0.2E_c I_g + E_s I_{se}}{1 + \beta_{dns}} \tag{6.6.21}
$$
Or,
$$
EI = \frac{0.4E_c I_g}{1 + \beta_{dns}} \tag{6.6.22}
$$
Alternatively, $EI$ shall be permitted to compute the value of $I$ from Equation 6.6.15 dividing by $(1 + \beta_{dns})$.
##### 6.3.10.6.2
The term $\beta_{dns}$ shall be taken as the ratio of maximum factored axial sustained load to maximum factored axial load associated with the same load combination, but shall not be taken greater than 1.0.
##### 6.3.10.6.3
The effective length factor, *k* shall be permitted to be taken as 1.0.
##### 6.3.10.6.4
For members with no transverse load between supports, $C_m$ shall be
taken as
$$
C_m = 0.6 + 0.4\frac{M_1}{M_2} \tag{6.6.23}
$$
Where, $M_1/M_2$ is positive if the column is bent in single curvature, and negative if the member is bent in double curvature. For members with transverse loads between supports, $C_m$ shall be taken as 1.0.
##### 6.3.10.6.5
Factored moment, $M_2$, about each axis separately, in Equation 6.6.18 shall not be taken less than
$$
M_{2,min} = P_u(15 + 0.03h) \tag{6.6.24}
$$
Where, $h$ is in mm and $P_u$ in N. For members in which $M_{2,min}$ exceeds $M_2$, the value of $C_m$ in Equation 6.6.23 shall either be taken equal to 1.0, or shall be based on the ratio of the computed end moments, $M_1/M_2$.
#### 6.3.10.7 Procedure for moment magnification - Sway
Moments $M_1$ and $M_2$ at the ends of an individual compression member shall be taken as
$$
M_1 = M_{1ns} + \delta_s M_{1s} \tag{6.6.25}
$$
$$
M_2 = M_{2ns} + \delta_s M_{2s} \tag{6.6.26}
$$
Where, $\delta_s$ is computed according to Sec 6.3.10.7.3 or Sec 6.3.10.7.4.
##### 6.3.10.7.1
Flexural members shall be designed for the total magnified end moments of the compression members at the joint.
##### 6.3.10.7.2
The values of Ec and *I* given in Sec 6.3.10.4 shall be used for determining the effective length factor *K* and it shall not be less than 1.0.
##### 6.3.10.7.3
The moment magnifier $\delta_s$ shall be calculated as
$$
\delta_s = \frac{1}{1 - Q} \geq 1 \tag{6.6.27}
$$
If $\delta_s$ calculated by Equation 6.6.27 exceeds 1.5, $\delta_s$ shall be calculated using second-order elastic analysis or 6.3.10.7.4.
##### 6.3.10.7.4
Alternatively, it shall be permitted to calculate $\delta_s$ as
$$
\delta_s = \frac{1}{1 - \frac{\Sigma P_u}{0.75\Sigma P_c}} \geq 1 \tag{6.6.28}
$$
Where, $\Sigma P_u$ is the summation for all the factored vertical loads in a story and $\Sigma P_c$ is the summation for all sway-resisting columns in a storey. $P_c$ is calculated using Equation 6.6.20 with $k$ determined from Sec 6.3.10.7.2 and $EI$ from Sec 6.3.10.6.1.
### 6.3.11 Axially Loaded Members Supporting Slab System
Axially loaded members supporting a slab system included within the scope of Sec 6.5.1 shall be designed as provided in Sec. 6.3 and in accordance with the additional requirements of Sec. 6.5.
### **6.3.12 Column Load Transmission through Floor System**
If $f_c'$ of a column is greater than 1.4 times that of the floor system, transmission of load through the floor system shall be provided by Sections 6.3.12.1, 6.3.12.2, or 6.3.12.3.
#### 6.3.12.1
Concrete of strength specified for the column shall be placed in the floor at the column location. Top surface of the column concrete shall extend 600 mm into the slab from face of column. Column concrete shall be well integrated with floor concrete, and shall be placed in accordance with relevant provisions for construction joints of columns, walls etc. with beams, slabs etc. To avoid accidental placing of lower strength concrete in the columns, the structural designer shall indicate on the drawing where the high and low strength concretes are to be placed.
#### 6.3.12.2
Strength of a column through a floor system shall be based on the lower value of concrete strength with vertical dowels and spirals as required.
#### 6.3.12.3
For columns laterally supported on four sides by beams of approximately equal depth or by slabs, it shall be permitted to base strength of the column on an assumed concrete strength in the column joint equal to 75 percent of column concrete strength plus 35 percent of floor concrete strength. In the application of Sec 6.3.12.3, ratio of column concrete strength to slab concrete strength shall not be taken larger than 2.5 in design.
### **6.3.13 Composite Compression Members**
#### 6.3.13.1
All members reinforced longitudinally with structural steel shapes, pipe, or tubing with or without longitudinal bars shall be included in composite compression members.
#### 6.3.13.2
A composite member strength shall be computed for the same limiting conditions applicable to ordinary reinforced concrete members.
#### 6.3.13.3
Any axial load strength assigned to concrete of a composite member shall be transferred to the concrete by members or brackets in direct bearing on the composite member concrete.
#### 6.3.13.4
All axial load strength not assigned to concrete of a composite member shall be developed by direct connection to the structural steel shape, pipe, or tube.
#### 6.3.13.5
For evaluation of slenderness effects, radius of gyration, $r$, of a composite section shall be not greater than the value given by
$$
r = \sqrt{\frac{0.2E_c I_g + E_s I_{sx}}{0.2E_c A_g + E_s A_{sx}}} \tag{6.6.29}
$$
And, as an alternative to a more accurate calculation, $EI$ in Equation 6.6.20 shall be taken either as Equation 6.6.21 or
$$
EI = \frac{0.2E_c I_g}{1 + \beta_d} + E_s I_{sx} \tag{6.6.30}
$$
#### 6.3.13.6 Concrete core encased by structural steel
##### 6.3.13.6.1
When a composite member is a structural steel encased concrete core,
the thickness of the steel encasement shall be not less than $b\sqrt{\frac{f_y}{3E_s}}$ for each face of width $b$ nor $b\sqrt{\frac{f_y}{8E_s}}$ for circular sections of diameter $h$
##### 6.3.13.6.2
When computing $A_{sx}$ and $I_{sx}$, longitudinal bars located within the encased concrete core shall be permitted to be used.
#### 6.3.13.7 Spiral reinforcement around structural steel core
A composite member with spirally reinforced concrete around a structural steel core shall conform to Sections 6.3.13.7.1 to 6.3.13.7.4.
##### 6.3.13.7.1
Design yield strength of structural steel core shall be the specified minimum yield strength for the grade of structural steel used but not to exceed 350 MPa.
##### 6.3.13.7.2
Spiral reinforcement shall conform to Sec 6.3.9.3.
##### 6.3.13.7.3
Longitudinal bars located within the spiral shall be not less than 0.01 nor more than 0.06 times net area of concrete section.
##### 6.3.13.7.4
Longitudinal bars located within the spiral shall be permitted to be used in computing *Asx* and *I sx* .
#### 6.3.13.8 Tie reinforcement around structural steel core
Laterally tied concrete around a structural steel core forming a composite member shall conform to Sections 6.3.13.8.1 to 6.3.13.8.7.
##### 6.3.13.8.1
Design yield strength of structural steel core shall be the specified minimum yield strength for the grade of structural steel used but not to exceed 350 MPa.
##### 6.3.13.8.2
Lateral ties shall extend completely around the structural steel core.
##### 6.3.13.8.3
Lateral ties shall have a diameter not less than 0.02 times the greatest side dimension of composite member, except that ties shall not be smaller than 10 mm diameter and are not required to be larger than 16 mm diameter. Welded wire reinforcement of equivalent area shall be permitted.
##### 6.3.13.8.4
Vertical spacing of lateral ties shall not exceed 16 longitudinal bar diameters, 48 tie bar diameters, or 0.5 times the least side dimension of the composite member.
##### 6.3.13.8.5
Longitudinal bars located within the ties shall be not less than 0.01 nor more than 0.06 times net area of concrete section.
##### 6.3.13.8.6
A longitudinal bar shall be located at every corner of a rectangular cross section, with other longitudinal bars spaced not farther apart than one half the least side dimension of the composite member.
##### 6.3.13.8.7
Longitudinal bars located within the ties shall be permitted to be used in computing *Asx* and *I sx* .
### **6.3.14 Bearing strength**
#### 6.3.14.1
Design bearing strength of concrete shall not exceed $\phi(0.85f_c'A_1)$, except when the supporting surface is wider on all sides than the loaded area, then the design bearing strength of the loaded area shall be permitted to be multiplied by $\sqrt{A_2/A_1}$ but by not more than 2 (Figure 6.6.6).
![Determination of loaded area A1 and supporting area A2 in stepped or sloped concrete supports using frustum method]()
### 6.3.15 Design for Flexure
#### 6.3.15.1 Design of Rectangular Beams
* (a) Formula for singly reinforced beams: The following equations which are based on the simplified stress block of Sec 6.3.2.7, are applicable to singly reinforced rectangular beams along with T-beams where the neutral axis lies within the flange.
Where,
$$
A_s = \frac{M_n}{f_y(d - a/2)} \tag{6.6.31}
$$
$$
a = \frac{A_s f_y}{0.85 f_c' b} \tag{6.6.32}
$$
By estimating an initial value of $a$, Equation 6.6.31 can be used to determine an approximate value of $A_s$. The value can be substituted in Equation 6.6.32 to get a better estimate of $a$ and hence a new $(d - a/2)$ can be determined for substitution in Equation 6.6.31.
In Equation 6.6.31, a preliminary value of nominal flexural strength of section, $M_n$ may be taken as factored moment at section, $M_u$ divided by strength reduction factor, $\phi$ = 0.9. Reinforcement ratio, $\rho = A_s/bd$ calculated on the basis of $A_s$ determined from Equation 6.6.31 shall not exceed $\rho_{max}$, where
$$
\rho_{max} = 0.85\beta_1\frac{f_c'}{f_y}\frac{\varepsilon_u}{\varepsilon_u + 0.004} \tag{6.6.33}
$$
and, $\varepsilon_u$ = 0.003
Additionally, $A_s$ determined from Equation 6.6.31 shall have to satisfy the requirements of minimum reinforcement for members in flexure as per Sec 6.3.5.
Revised $\phi$ shall be determined from Sec 6.2.3.2 based on either $c/d_t = a/\beta_1d_t$ or $\varepsilon_t$, where, $\varepsilon_t$ is the net tensile strain in the reinforcement furthest from the compression face of the concrete at the depth $d_t$. Strain, $\varepsilon_t$ may be calculated from Equation 6.6.33 by replacing 0.004 by $\varepsilon_t$ and $\rho_{max}$ by $\rho$ respectively.
(b) Design formulae for doubly reinforced beams: A doubly reinforced beam shall be designed only when there is a restriction on depth of beam and maximum tensile reinforcement allowed cannot produce the required moment $M_u$.
To establish if doubly reinforced beam is required the following approach can be followed:
Determine,
$$
\rho_{0.005} = 0.85\beta_1\frac{f_c'}{f_y}\frac{\varepsilon_u}{\varepsilon_u + 0.005} \tag{6.6.34}
$$
$$
A_s = \rho_{0.005}bd \qquad a = \frac{A_s f_y}{0.85 f_c' b} \qquad \phi M_n = \phi A_s f_y\left(d - \frac{a}{2}\right) \tag{6.6.35}
$$
If $\phi M_n$ is less than required moment $M_u$ with $\phi$ = 0.9, a doubly reinforced beam is needed and then taking values of $A_s$ and $\phi M_n$ from above, put
$A_{s1} = A_s$ and $\phi M_{n1} = \phi M_n$
Then, the following values are to be evaluated,
$$
\phi M_{n2} = M_u - \phi M_{n1} \tag{6.6.36}
$$
$$
A_{s2} = \frac{\phi M_{n2}}{\phi f_y(d - d')}
$$
Assuming compression steel yields (needs to be checked later),
$A_s' = A_{s2}$
$A_s = A_{s1} + A_{s2}$
Check $\rho \geq \bar{\rho}_{cy}$ for compression steel yielding, where
$$
\bar{\rho}_{cy} = 0.85\beta_1\frac{f_c'}{f_y}\frac{d'}{d}\frac{\varepsilon_u}{\varepsilon_u - \varepsilon_y} + \rho' \tag{6.6.37}
$$
If $\rho \geq \bar{\rho}_{cy}$ (i.e. compression steel yields),
Find $a = \frac{(A_s - A_s')f_y}{0.85f_c'b}$ and find $c$, $\varepsilon_t$ and confirm $\phi$ = 0.9 in the above equations. Value of $\phi$ shall be determined from Sec 6.2.3.2 based on either $c/d_t = a/\beta_1d_t$ or $\varepsilon_t$, as stated above for rectangular beams.
If compression steel does not yield, $c$ is to be found from concrete section force equilibrium condition, C=T which will result in a quadratic equation of $c$. $f_s'$ needs to be calculated from strain diagram and $A_s'$ revised.
$$
A_s' = A_{s2}\frac{f_y}{f_s'}
$$
$A_s = A_{s1} + A_{s2}$
$\varepsilon_t$ shall be calculated from $c$ for finding $\phi$.
#### 6.3.15.2 Design of T-Beams
* (a) General: For effective widths and other parameters for T, L or isolated beams, Sections 6.1.13.2 to 6.1.13.4 shall apply.
* (b) Formulae for T-beams : A T-beam shall be treated as a rectangular beam if $a \leq h_f$ where $a$ is obtained from Eq. 6.6.32 In using Eq. 6.6.32, if $A_s$ is not known, it may be initially assumed as :
$$
A_s = \frac{M_n}{f_y(d - h_f/2)} \tag{6.6.38}
$$
If $a$, thus obtained, is greater than $h_f$ the beam shall be considered as a T-beam, in which case the following formulae shall be applicable :
$$
A_{sf} = \frac{0.85f_c'(b - b_w)h_f}{f_y} \tag{6.6.39}
$$
$$
M_{n1} = A_{sf} f_y\left(d - \frac{h_f}{2}\right) \tag{6.6.40}
$$
$$
M_{n2} = M_n - M_{n1} \tag{6.6.41}
$$
$$
A_s - A_{sf} = \frac{M_{n2}}{f_y(d - a/2)} \tag{6.6.42}
$$
$$
a = \frac{(A_s - A_{sf})f_y}{0.85f_c'b_w} \tag{6.6.43}
$$
By estimating an initial value of $a$, Eq. 6.6.42 can be used to obtain an approximate value of $(A_s - A_{sf})$ That value of $(A_s - A_{sf})$ can be substituted in Eq. 6.6.43 to get a better estimate of $a$.
Net tensile strain requirements will be satisfied as long as depth to neutral axis, $c \leq 0.429d_t$. This will occur if:
$$
\rho_w < \rho_{w,max}
$$
Where,
$$
\rho_w = \frac{A_s}{b_wd} \tag{6.6.44}
$$
$$
\rho_{w,max} = \rho_{max} + \rho_f \tag{6.6.45}
$$
$$
\rho_f = \frac{A_{sf}}{b_wd} \tag{6.6.46}
$$
and, $\rho_{max}$ is as defined by Eq. 6.6.33. For $c/d_t$ ratios between 0.429 and 0.375, equivalent to $\rho_w$ between the $\rho_{w,max}$ from Eq. 6.6.45 and $\rho_{w,max}$ calculated by substituting $\rho_{max}$ from Eq. 6.6.33 with 0.005 in place of 0.004 and $\rho_w$ for $\rho_{max}$, the strength reduction factor, $\phi$ must be adjusted for $\varepsilon_t$ in accordance with Sec 6.2.3.2.
## **6.4 Shear and Torsion**
### **6.4.1 Shear Strength**
#### 6.4.1.1
Except for members designed in accordance with Appendix I, design of cross sections subject to shear shall be based on
$$
\phi V_n \geq V_u \tag{6.6.47}
$$
Where, $V_u$ is the factored shear force at the section considered and $V_n$ is nominal shear strength given by
$$
V_n = V_c + V_s \tag{6.6.48}
$$
Where, $V_c$ is nominal shear strength provided by concrete calculated in accordance with Sec 6.4.2, or Sec 6.4.10, and $V_s$ is nominal shear strength provided by shear reinforcement calculated in accordance with Sec 6.4.3, Sec 6.4.8.9, or Sec 6.4.10.
##### 6.4.1.1.1
The effect of any openings in members shall be considered in determining Vn .
##### 6.4.1.1.2
In evaluating *V c*, whenever applicable, effects of axial tension due to creep and shrinkage in restrained members shall be considered and effects of inclined flexural compression in variable depth members shall be permitted to be included.
#### 6.4.1.2
Except as allowed in Sec 6.4.1.2.1, the values of $\sqrt{f_c'}$ used in this Chapter shall not exceed 8.3 MPa.
##### 6.4.1.2.1
Values of $f_c'$ greater than 8.3 MPa shall be permitted in computing $V_c$, $V_{cw}$, and $V_{ci}$ for reinforced concrete beams and concrete joist construction having minimum web reinforcement in accordance with Sec 6.4.3.5.3, or Sec 6.4.4.5.2.
#### 6.4.1.3
Computation of maximum $V_u$ at supports in accordance with Sec 6.4.1.3.1 shall be permitted if all conditions (a), (b), and (c) are satisfied:
* (a) Support reaction, in direction of applied shear, introduces compression into the end regions of member;
* (b) Loads are applied at or near the top of the member;
* (c) No concentrated load occurs between face of support and location of critical section defined in Sec 6.4.1.3.1.
##### 6.4.1.3.1
Sections located less than a distance *d* from face of support shall be permitted to be designed for Vu computed at a distance *d* .
#### 6.4.1.4
For deep beams, brackets and corbels, walls, and slabs and footings, the special provisions of Sections 6.4.6 to 6.4.10 shall apply.
### **6.4.2 Contribution of Concrete to Shear Strength**
#### 6.4.2.1
$V_c$ shall be computed by provisions of Sections 6.4.2.1.1 to 6.4.2.1.3, unless a more detailed calculation is made in accordance with Sec 6.4.2.2. Throughout this Chapter, except in Sec 6.4.5, $\lambda$ shall be as defined in Sec 6.1.8.1.
##### 6.4.2.1.1
For members subject to shear and flexure only,
$$
V_c = 0.17\lambda\sqrt{f_c'}\,b_wd \tag{6.6.49}
$$
##### 6.4.2.1.2
For members subject to axial compression,
$$
V_c = 0.17\left(1 + \frac{N_u}{14A_g}\right)\lambda\sqrt{f_c'}\,b_wd \tag{6.6.50}
$$
Quantity $N_u/A_g$ shall be expressed in MPa.
##### 6.4.2.1.3
For members subject to significant axial tension, Vc shall be taken as zero unless a more detailed analysis is made using Sec 6.4.2.2.3.
#### 6.4.2.2
$V_c$ shall be permitted to be computed by more detailed calculation of Sections 6.4.2.2.1 to 6.4.2.2.3.
##### 6.4.2.2.1
For members subject to shear and flexure only,
$$
V_c = \left(0.16\lambda\sqrt{f_c'} + 17\rho_w\frac{V_u d}{M_u}\right) b_wd \tag{6.6.51}
$$
But, not greater than $0.29\lambda\sqrt{f_c'}\,b_wd$. When computing $V_c$ by Eq. 6.6.51, $V_u d/M_u$ shall not be taken greater than 1.0, where $M_u$ occurs simultaneously with $V_u$ at section considered.
##### 6.4.2.2.2
For members subject to axial compression, it shall be permitted to compute $V_c$ using Eq. 6.6.51 with $M_m$ substituted for $M_u$ and $V_u d/M_u$ not then limited to 1.0, where
$$
M_m = M_u - \frac{N_u(4h - d)}{8} \tag{6.6.52}
$$
However, $V_c$ shall not be taken greater than
$$
V_c = 0.29\lambda\sqrt{f_c'}\,b_wd\sqrt{1 + \frac{0.29N_u}{A_g}} \tag{6.6.53}
$$
$N_u/A_g$ shall be expressed in MPa. When $M_m$ as computed by Eq. 6.6.52 is negative, $V_c$ shall be computed by Eq. 6.6.53.
##### 6.4.2.2.3
For members subject to significant axial tension,
$$
V_c = 0.17\left(1 + \frac{0.29N_u}{A_g}\right)\lambda\sqrt{f_c'}\,b_wd \tag{6.6.54}
$$
But, not less than zero, where $N_u$ is negative for tension. $N_u/A_g$ shall be expressed in MPa.
#### 6.4.2.3
For circular members, the area used to compute $V_c$ shall be taken as the product of the diameter and effective depth of the concrete section. It shall be permitted to take $d$ as 0.80 times the diameter of the concrete section.
### **6.4.3 Shear Strength Contribution of Reinforcement**
#### 6.4.3.1 Types of shear reinforcement
##### 6.4.3.1.1
The following types of shear reinforcement shall be permitted:
* (a) Stirrups perpendicular to axis of member;
* (b) Welded wire reinforcement with wires located perpendicular to axis of member;
* (c) Spirals, circular ties, or hoops.
* (d) Stirrups making an angle of 45o or more with longitudinal tension reinforcement;
* (e) Longitudinal reinforcement with bent portion making an angle of 30o or more with the longitudinal tension reinforcement;
* (f) Combinations of stirrups and bent longitudinal reinforcement.
#### 6.4.3.2
The values of $f_y$ and $f_{yt}$ used in design of shear reinforcement shall not exceed 420 MPa, except the value shall not exceed 550 MPa for welded deformed wire reinforcement.
#### 6.4.3.3
Stirrups and other bars or wires used as shear reinforcement shall extend to a distance $d$ from extreme compression fiber and shall be developed at both ends according to Sec 8.2.10.
#### 6.4.3.4 Limits in spacing for shear reinforcement
##### 6.4.3.4.1
Spacing of shear reinforcement placed perpendicular to member axis shall not exceed $d/2$ nor 600 mm.
##### 6.4.3.4.2
The spacing of inclined stirrups and bent longitudinal reinforcement shall be such that every 45-degree line, extending toward the reaction from middepth of member $d/2$ to longitudinal tension reinforcement, shall be crossed by at least one line of shear reinforcement.
##### 6.4.3.4.3
Where, $V_s$ exceeds $0.33\sqrt{f_c'}b_wd$, maximum spacing given in Sections 6.4.3.4.1 and 6.4.3.4.2 shall be reduced by one-half.
#### 6.4.3.5 Minimum shear reinforcement
##### 6.4.3.5.1
A minimum area of shear reinforcement, *Av,min* , shall be provided in all reinforced concrete flexural members, where *Vu* exceeds 0.5 $\phi$ *Vc* , except in members satisfying one or more of (a) to (f):
* (a) Footings and solid slabs;
* (b) Hollow-core units with total untopped depth not greater than 315 mm and hollow-core units where $V_u$ is not greater than 0.5$\phi$ *Vcw* ;
* (c) Concrete joist construction defined by Sec 6.1.14;
* (d) Beams with ℎ not greater than 250 mm;
* (e) Beam integral with slabs with ℎnot greater than 600 mm and not greater than the larger of 2.5 times thickness of flange, and 0.5 times width of web;
* (f) Beams constructed of steel fiber-reinforced, normal weight concrete with *′* not exceeding 40 MPa, ℎ not greater than 600 mm, and $V_u$ not greater than $0.17\phi\sqrt{f_c'}b_wd$.
##### 6.4.3.5.2
Minimum shear reinforcement requirements of Sec 6.4.3.5.1 shall be permitted to be waived if shown by test that required ph and $V_n$ can be developed when shear reinforcement is omitted. Such tests shall simulate effects of differential
settlement, creep, shrinkage, and temperature change, based on a realistic assessment of such effects occurring in service.
##### 6.4.3.5.3
Where shear reinforcement is required by Sec 6.4.3.5.1 or for strength and where Sec 6.4.4.1 allows torsion to be neglected, $A_{v,min}$ shall be computed by
$$
A_{v,min} = 0.062\sqrt{f_c'}\frac{b_ws}{f_{yt}} \tag{6.6.55}
$$
But, shall not be less than $(0.35b_ws)/f_{yt}$.
#### 6.4.3.6 Design of shear reinforcement
##### 6.4.3.6.1
Where *Vu* exceeds $\phi$ *Vc* , shear reinforcement shall be provided to satisfy Equations 6.6.47 and 6.6.48, where *Vs* shall be computed in accordance with Sections 6.4.3.6.2 to 6.4.3.6.9.
##### 6.4.3.6.2
Where shear reinforcement perpendicular to axis of member is used,
$$
V_s = \frac{A_vf_{yt}d}{s} \tag{6.6.56}
$$
Where, $A_v$ is the area of shear reinforcement within spacing $s$.
##### 6.4.3.6.3
Where circular ties, hoops, or spirals are used as shear reinforcement, *Vs* shall be computed using Eq. 6.6.56 where *d* is defined in Sec 6.4.2.3 for circular members, *A* ν shall be taken as two times the area of the bar in a circular tie, hoop, or spiral at a spacing *S* , ø is measured in a direction parallel to longitudinal reinforcement, and *fyt* is the specified yield strength of circular tie, hoop, or spiral reinforcement.
##### 6.4.3.6.4
Where inclined stirrups are used as shear reinforcement,
$$
V_s = \frac{A_vf_{yt}(\sin\alpha + \cos\alpha)d}{s} \tag{6.6.57}
$$
Where, $\alpha$ is angle between inclined stirrups and longitudinal axis of the member, and $s$ is measured in direction parallel to longitudinal reinforcement.
##### 6.4.3.6.5
Where shear reinforcement consists of a single bar or a single group of parallel bars, all bent up at the same distance from the support,
$$
V_s = A_vf_y\sin\alpha \tag{6.6.58}
$$
But, not greater than $0.25\sqrt{f_c'}b_wd$, where α is angle between bent-up reinforcement and longitudinal axis of the member.
##### 6.4.3.6.6
Where shear reinforcement consists of a series of parallel bent-up bars or groups of parallel bent-up bars at different distances from the support, *Vs* shall be computed by Eq. 6.6.57.
##### 6.4.3.6.7
Only the center three-fourths of the inclined portion of any longitudinal bent bar shall be considered effective for shear reinforcement.
##### 6.4.3.6.8
Where more than one type of shear reinforcement is used to reinforce the same portion of a member, *Vs* shall be computed as the sum of the values computed for the various types of shear reinforcement.
##### 6.4.3.6.9
$V_s$ shall not be taken greater than $0.66\sqrt{f_c'}d_wd$.
### **6.4.4 Design for Torsion**
Design for torsion shall be done as per Sections 6.4.4.1 to 6.4.4.6. A beam subjected to torsion is idealized as a thin-walled tube with the core concrete cross section in a solid beam neglected as shown in Figure 6.6.7.
![Torsional resistance idealized by thin-walled tube model and ineffective inner area enclosed by shear flow path]()
#### 6.4.4.1 Threshold torsion
It shall be permitted to neglect torsion effects if the factored torsional moment $T_u$ is less than:
* (a) For members not subjected to axial tension or compression
$$
0.083\phi\lambda\sqrt{f_c'}\left(\frac{A_{cp}^2}{p_{cp}}\right)
$$
* (b) For members subjected to an axial compressive or tensile force
$$
0.083\phi\lambda\sqrt{f_c'}\left(\frac{A_{cp}^2}{p_{cp}}\right)\sqrt{1 + \frac{N_u}{0.33A_g\lambda\sqrt{f_c'}}}
$$
The overhanging flange width used in computing $A_{cp}$ and $p_{cp}$ for members cast monolithically with a slab shall conform to Sec 6.5.2.4. For a hollow section, $A_g$ shall be used in place of $A_{cp}$ in Sec 6.4.4.1, and the outer boundaries of the section shall conform to Sec 6.5.2.4.
##### 6.4.4.1.1
For members cast monolithically with a slab and for isolated members with flanges, the overhanging flange width used to compute *Acp* and *Ρcp* shall conform to Sec 6.5.2.4, except that the overhanging flanges shall be neglected in cases where the parameter *A**2* cp / *Ρcp* calculated for a beam with flanges is less than that computed for the same beam ignoring the flanges.
#### 6.4.4.2 Evaluation of factored torsional moment
##### 6.4.4.2.1
If the factored torsional moment, *Tu* , in a member is required to maintain equilibrium Figure 6.6.8 and exceeds the minimum value given in Sec 6.4.4.1, the member shall be designed to carry *Tu* in accordance with Sections 6.4.4.3 to 6.4.4.6.
##### 6.4.4.2.2
In a statically indeterminate structure where reduction of the torsional moment in a member can occur due to redistribution of internal forces upon cracking Figure 6.6.9, the maximum *Tu* shall be permitted to be reduced to the values given in (a), or (b) as applicable:
* (a) For members, at the sections described in Sec 6.4.4.2.4 and not subjected to axial tension or compression
$$
0.33\phi\lambda\sqrt{f_c'}\left(\frac{A_{cp}^2}{p_{cp}}\right)
$$
* (b) For members subjected to an axial compressive or tensile force
$$
0.33\phi\lambda\sqrt{f_c'}\left(\frac{A_{cp}^2}{p_{cp}}\right)\sqrt{1 + \frac{N_u}{0.33A_g\lambda\sqrt{f_c'}}}
$$
In (a), or (b), the correspondingly redistributed bending moments and shears in the adjoining members shall be used in the design of these members. For hollow sections, $A_{cp}$ shall not be replaced with $A_g$ in Sec 6.4.4.2.2.
![Design torque may not be reduced because moment redistribution is not possible]()
![Design torque for spandrel beam may be reduced because moment redistribution is possible]()
##### 6.4.4.2.3
It shall be permitted to take the torsional loading from a slab as uniformly distributed along the member, if not determined by a more exact analysis.
##### 6.4.4.2.4
Sections located closer than a distance *d* from the face of a support shall be designed for not less than *Tu* computed at a distance *d* . If a concentrated torque occurs within this distance, the critical section for design shall be at the face of the support.
#### 6.4.4.3 Torsional moment strength
##### 6.4.4.3.1
The cross-sectional dimensions shall be such that:
* (a) For solid sections
$$
\sqrt{\left(\frac{V_u}{b_wd}\right)^2 + \left(\frac{T_uP_h}{1.7A_{oh}^2}\right)^2} \leq \phi\left(\frac{V_c}{b_wd} + 0.66\sqrt{f_c'}\right) \tag{6.6.59}
$$
* (b) For hollow sections
$$
\left(\frac{V_u}{b_wd}\right) + \left(\frac{T_uP_h}{1.7A_{oh}^2}\right) \leq \phi\left(\frac{V_c}{b_wd} + 0.66\sqrt{f_c'}\right) \tag{6.6.60}
$$
Superposition of shear stresses due to shear and torsion in hollow sections given by the left side of the inequality Sec 6.4.14 is illustrated by Figure 6.6.10(a) and that in solid sections given by the left side of the inequality Sec 6.4.13 is illustrated by Figure 6.6.10(b).
##### 6.4.4.3.2
If the wall thickness varies around the perimeter of a hollow section, Eq. 6.6.60 shall be evaluated at the location where the left-hand side of Eq. 6.6.60 is a maximum.
![Superposition of torsional and shear stresses in hollow and solid cross sections]()
##### 6.4.4.3.3
If the wall thickness is less than $A_{oh}/p_h$, the second term in Eq. 6.4.14 shall be taken as
$$
\left(\frac{T_u}{1.7A_{oh}t}\right)
$$
Where, $t$ is the thickness of the wall of hollow section at the location where the stresses are being checked.
##### 6.4.4.3.4
The values of $f_y$ and $f_{yt}$ used for design of torsional reinforcement shall not exceed 420 MPa.
##### 6.4.4.3.5
Where $T_u$ exceeds the threshold torsion, design of the cross section shall be based on
$$
\phi T_n \geq T_u \tag{6.6.61}
$$
##### 6.4.4.3.6
$T_u$ shall be computed by
$$
T_n = \frac{2A_oA_tf_{yt}}{s}\cot\theta \tag{6.6.62}
$$
Where, $A_o$ shall be determined by analysis except that it shall be permitted to take $A_o$ equal to 0.85$A_{oh}$; $\theta$ shall not be taken smaller than 30o nor larger than 60o . It shall be permitted to take θ equal to 45o .
##### 6.4.4.3.7
The additional area of longitudinal reinforcement to resist torsion, $A_l$, shall not be less than
$$
A_l = \frac{A_t}{s}p_h\left(\frac{f_{yt}}{f_y}\right)\cot^2\theta \tag{6.6.63}
$$
Where, $\theta$ shall be the same value used in Eq. 6.6.62 and $A_t/s$ shall be taken as the amount computed from Eq. 6.6.62 not modified in accordance with Sec 6.4.4.5.2 or Sec 6.4.4.5.3; $f_{yt}$ refers to closed transverse torsional reinforcement, and $f_y$ refers to longitudinal torsional reinforcement.
##### 6.4.4.3.8
Reinforcement required for torsion shall be added to that required for the shear, moment, and axial force that act in combination with the torsion. The most restrictive requirements for reinforcement spacing and placement shall be met.
##### 6.4.4.3.9
It shall be permitted to reduce the area of longitudinal torsion reinforcement in the flexural compression zone by an amount equal to $M_u/(0.9df_y)$, where $M_u$ occurs at the section simultaneously with $T_u$, except that the reinforcement provided shall not be less than that required by Sec 6.4.4.5.3 or Sec 6.4.4.6.2.
#### 6.4.4.4 Details of torsional reinforcement
##### 6.4.4.4.1
Torsion reinforcement shall consist of longitudinal bars or tendons and one or more of the following:
* (a) Closed stirrups or closed ties, perpendicular to the axis of the member;
* (b) A closed cage of welded wire reinforcement with transverse wires perpendicular to the axis of the member;
* (c) Spiral reinforcement.
##### 6.4.4.4.2
Transverse torsional reinforcement shall be anchored by one of the following:
* (a) A 135o standard hook, or seismic hook as defined in Sec 8.1.2.1(d) Chapter 8, around a longitudinal bar;
* (b) According to Sec 8.2.10.2 Chapter 8 in regions where the concrete surrounding the anchorage is restrained against spalling by a flange or slab or similar member.
##### 6.4.4.4.3
Longitudinal torsion reinforcement shall be developed at both ends.
##### 6.4.4.4.4
For hollow sections in torsion, the distance from the centerline of the transverse torsional reinforcement to the inside face of the wall of the hollow section shall not be less than 0.5 *Aoh* /*P* *h* .
#### 6.4.4.5 Minimum torsion reinforcement
##### 6.4.4.5.1
A minimum area of torsional reinforcement shall be provided in all regions, where *Tu* exceeds the threshold torsion given in Sec 6.4.4.1.
##### 6.4.4.5.2
Where torsional reinforcement is required by Sec 6.4.4.5.1, the minimum area of transverse closed stirrups shall be computed by
But, shall not be less than (0.35$b_w$)⁄.
##### 6.4.4.5.3
Where torsional reinforcement is required by Sec 6.4.4.5.1, the minimum total area of longitudinal torsional reinforcement, *Al,min* , shall be computed by
Where, $A_l$ shall not be taken less than 0.175y^⁄; refers to closed transverse torsional reinforcement, and refers to longitudinal reinforcement.
#### 6.4.4.6 Spacing of torsion reinforcement
##### 6.4.4.6.1
The spacing of transverse torsion reinforcement shall not exceed the smaller of $P_h/8$ or 300 mm.
##### 6.4.4.6.2
The longitudinal reinforcement required for torsion shall be distributed around the perimeter of the closed stirrups with a maximum spacing of 300 mm. The longitudinal bars shall be inside the stirrups. There shall be at least one longitudinal bar in each corner of the stirrups. Longitudinal bars shall have a diameter at least 0.042 times the stirrup spacing, but not less than 10 mm diameter.
##### 6.4.4.6.3
Torsional reinforcement shall be provided for a distance of at least $(b_t + d)$ beyond the point required by analysis.
### 6.4.5 Shear-Friction
#### 6.4.5.1
Application of provisions of Sec 6.4.5 shall be for cases where it is appropriate to consider shear transfer across a given plane, such as: an existing or potential crack, an interface between dissimilar materials, or an interface between two concretes cast at different times.
#### 6.4.5.2
Design of cross sections subject to shear transfer as described in Sec 6.4.5.1 shall be based on Eq. 6.6.47, where $V_n$ is calculated in accordance with provisions of Sec 6.4.5.3 or Sec 6.4.5.4.
#### 6.4.5.3
A crack shall be assumed to occur along the shear plane considered. The required area of shear-friction reinforcement -M\` across the shear plane shall be designed using either Sec 6.4.5.4 or any other shear transfer design methods that result in prediction of strength in substantial agreement with results of comprehensive tests.
##### 6.4.5.3.1
Provisions of Sections 6.4.5.5 to 6.4.5.10 shall apply for all calculations of shear transfer strength.
#### 6.4.5.4 Design method for shear-friction
##### 6.4.5.4.1
Where shear-friction reinforcement is perpendicular to the shear plane, $V_n$ shall be computed by
$$
V_n = A_{vf}f_y\mu \tag{6.6.66}
$$
Where, $\mu$ is coefficient of friction in accordance with Sec 6.4.5.4.3.
##### 6.4.5.4.2
Where shear-friction reinforcement is inclined to the shear plane, such that the shear force produces tension in shear-friction reinforcement Figure 6.6.11, $V_n$ shall be computed by
$$
V_n = A_{vf}f_y(\mu\sin\alpha + \cos\alpha) \tag{6.6.67}
$$
Where, $\alpha$ is angle between shear-friction reinforcement and shear plane.
![Shear-friction reinforcement inclined at an angle alpha to the assumed crack and shear plane]()
##### 6.4.5.4.3
The coefficient of friction μ in Eq. 6.6.66 and Eq. 6.6.67 shall be taken as:
* (a) Concrete placed monolithically $1.4\lambda$
* (b) Concrete placed against hardened concrete with surface intentionally 1.0¥ roughened as specified in Sec 6.4.5.9
* (c) Concrete placed against hardened concrete not intentionally $0.6\lambda$ roughened
* (d) Concrete anchored to as-rolled structural steel by headed studs or by $0.7\lambda$ reinforcing bars (see 6.4.5.10)
Where, ¥ = 1.0 for normal weight concrete and 0.75 for all light weight concrete. Otherwise, λ shall be determined based on volumetric proportions of light weight and normal weight aggregates as specified in Sec 6.1.8.1, but shall not exceed 0.85.
#### 6.4.5.5
For normal weight concrete either placed monolithically or placed against hardened concrete with surface intentionally roughened as specified in Sec 6.4.5.9, $V_n$ shall not exceed the smallest of 0.2*′* -, (3.3 + 0.08*′* )- and 11-, where - is area of concrete section resisting shear transfer. For all other cases, $V_n$ shall not exceed the smaller of 0.2*′* - or 5.5- *.* Where concretes of different strengths are cast against each other, the value of *′* used to evaluate $V_n$ shall be that of the lowerstrength concrete.
#### 6.4.5.6
The value of used for design of shear-friction reinforcement shall not exceed 420 MPa.
#### 6.4.5.7
Net tension across shear plane shall be resisted by additional reinforcement. Permanent net compression across shear plane shall be permitted to be taken as additive to -M`, the force in the shear-friction reinforcement, when calculating required -M`.
#### 6.4.5.8
Shear-friction reinforcement shall be appropriately placed along the shear plane and shall be anchored to develop on both sides by embedment, hooks, or welding to special devices.
#### 6.4.5.9
For the purpose of Sec 6.4.5, when concrete is placed against previously hardened concrete, the interface for shear transfer shall be clean and free of laitance. If ¦ is assumed equal to 1.0¥, interface shall be roughened to a full amplitude of approximately 6 mm.
#### 6.4.5.10
When shear is transferred between as-rolled steel and concrete using headed studs or welded reinforcing bars, steel shall be clean and free of paint.
### **6.4.6 Deep Beams**
#### 6.4.6.1
The provisions of Sec 6.4.6 shall apply to members with $l_n$ not exceeding four times the overall member depth or regions of beams with concentrated loads within twice the member depth from the support that are loaded on one face and supported on the opposite face so that compression struts can develop between the loads and supports. See also Sec 8.2.7.6 Chapter 8.
#### 6.4.6.2
Deep beams shall be designed using provisions of either nonlinear analysis as permitted in Sec 6.3.7.1, or Appendix I.
#### 6.4.6.3
$V_n$ for deep beams shall not exceed $0.83\sqrt{f_c'}b_wd$.
#### 6.4.6.4
The area of shear reinforcement perpendicular to the flexural tension reinforcement, $A_v$, shall not be less than $0.0025b_ws$, and $s$ shall not exceed the smaller of $d/5$ and 300 mm.
#### 6.4.6.5
The area of shear reinforcement parallel to the flexural tension reinforcement, $A_{vh}$, shall not be less than $0.0015b_ws_2$, and $s_2$ shall not exceed the smaller of $d/5$ and 300 mm.
#### 6.4.6.6
It shall be permitted to provide reinforcement satisfying Sec I.3.3 Appendix I instead of the minimum horizontal and vertical reinforcement specified in Sections 6.4.6.4 and 6.4.6.5.
### **6.4.7 Provisions for Brackets and Corbels**
#### 6.4.7.1
Brackets and corbels, Figures 6.6.12 and 6.6.13, with a shear span-to-depth ratio $\dfrac{a_v}{d}$ less than 2 shall be permitted to be designed using Appendix I. Design shall be permitted using Sections 6.4.7.3 and 6.4.7.4 for brackets and corbels with:
* (a) $\dfrac{a_v}{d}$ not greater than 1, and
* (b) Subject to factored horizontal tensile force, $N_{uc}$, not larger than $V_u$.
The requirements of Sections 6.4.7.2, 6.4.7.5, 6.4.7.6, and 6.4.7.7 shall apply to design of brackets and corbels. Effective depth 0 shall be determined at the face of the support.
#### 6.4.7.2
Depth at outside edge of bearing area shall not be less than $0.5d$.
#### 6.4.7.3
Section at face of support shall be designed to resist simultaneously $V_u$, a factored moment $[V_ua_v + N_{uc}(h-d)]$, and a factored horizontal tensile force $N_{uc}$.
##### 6.4.7.3.1
In all design calculations in accordance with Sec 6.4.7, $\phi$ shall be taken equal to 0.75.
##### 6.4.7.3.2
Design of shear-friction reinforcement, *Aνf* to resist *Vu* shall be in accordance with Sec 6.4.5.
* (a) For normal weight concrete, $V_n$ shall not exceed the smallest of (i) $0.2f_c'b_wd$, (ii) $(3.3 + 0.08f_c')b_wd$, and (iii) $11b_wd$.
* (b) For all-lightweight or sand-lightweight concrete, $V_n$ shall not be taken greater than the smaller of $\left(0.2 - \dfrac{0.07a_v}{d}\right)f_c'b_wd$ and $\left(5.5 - \dfrac{1.9a_v}{d}\right)b_wd$.
##### 6.4.7.3.3
Reinforcement $A_f$ to resist factored moment $[V_ua_v + N_{uc}(h-d)]$ shall
be computed in accordance with Sections 6.3.2 and 6.3.3.
![Structural action and internal forces of a reinforced concrete corbel]()
![Geometric dimensions and reinforcement notation used for brackets and corbels]()
##### 6.4.7.3.4
Reinforcement $A_n$ to resist factored tensile force $N_{uc}$ shall be determined from $\phi A_n f_y \geq N_{uc}$. Factored tensile force, $N_{uc}$, shall not be taken less than $0.2V_u$ unless provisions are made to avoid tensile forces. $N_{uc}$ shall be regarded as live load even if tension results from restraint of creep, shrinkage, or temperature change.
##### 6.4.7.3.5
Area of primary tension reinforcement $A_{sc}$ shall not be less than the larger of $(A_f + A_n)$ and $\left(\dfrac{2A_{vf}}{3} + A_n\right)$.
#### 6.4.7.4
Total area, $A_h$, of closed stirrups or ties parallel to primary tension reinforcement shall not be less than $0.5(A_{sc} - A_n)$. Distribute $A_h$ uniformly within $\left(\dfrac{2}{3}\right)d$ adjacent to primary tension reinforcement.
#### 6.4.7.5
$\dfrac{A_{sc}}{bd}$ shall not be less than $0.04\left(\dfrac{f_c'}{f_y}\right)$.
#### 6.4.7.6
At front face of bracket or corbel, primary tension reinforcement shall be anchored by one of the following:
* (a) By a structural weld to a transverse bar of at least equal size; weld to be designed to develop of primary tension reinforcement;
* (b) By bending primary tension reinforcement back to form a horizontal loop; or
* (c) By some other means of positive anchorage.
#### 6.4.7.7
Bearing area on bracket or corbel neither shall project beyond straight portion of primary tension reinforcement, nor shall project beyond interior face of transverse anchor bar (if one is provided).
### **6.4.8 Provisions for Walls**
#### 6.4.8.1
Design of walls for shear forces perpendicular to face of wall shall be in accordance with provisions for slabs in Sec 6.4.10. Design for horizontal in-plane shear forces in a wall shall be in accordance with Sections 6.4.8.2 to 6.4.8.9. Alternatively, it shall be permitted to design walls with a height not exceeding two times the length of the wall for horizontal shear forces in accordance with Appendix I and Sections 6.4.8.9.2 to 6.4.8.9.5.
#### 6.4.8.2
Design of horizontal section for shear in plane of wall shall be based on Equations 6.6.47 and 6.6.48, where $V_c$ shall be in accordance with Sec 6.4.8.5 or Sec 6.4.8.6 and $V_s$ shall be in accordance with Sec 6.4.8.9.
#### 6.4.8.3
$V_n$ at any horizontal section for shear in plane of wall shall not be taken greater than $0.83\sqrt{f_c'}\,h\,d$, where $h$ is thickness of wall, and $d$ is defined in Sec 6.4.8.4.
#### 6.4.8.4
For design for horizontal shear forces in plane of wall, $d$ shall be taken equal to $0.8l_w$. A larger value of $d$, equal to the distance from extreme compression fiber to center of force of all reinforcement in tension, shall be permitted to be used when determined by a strain compatibility analysis.
#### 6.4.8.5
If a more detailed calculation is not made in accordance with Sec 6.4.8.6, $V_c$ shall not be taken greater than $0.17\lambda\sqrt{f_c'}\,h\,d$ for walls subject to axial compression, or $V_c$ shall not be taken greater than the value given in 6.4.2.2.3 for walls subject to axial tension.
#### 6.4.8.6
$V_c$ shall be permitted to be the lesser of the values computed from Equations 6.6.68 and 6.6.69
$$
V_c = 0.27\lambda\sqrt{f_c'}\,hd + \frac{N_ud}{4l_w} \tag{6.6.68}
$$
Or,
$$
V_c = \left[0.05\lambda\sqrt{f_c'} + \frac{l_w\left(0.1\lambda\sqrt{f_c'} + 0.2\dfrac{N_u}{l_wh}\right)}{\dfrac{M_u}{V_u} - \dfrac{l_w}{2}}\right]hd \tag{6.6.69}
$$
Where, $l_w$ is the overall length of the wall, and $N_u$ is positive for compression and negative for tension. If $\left(\dfrac{M_u}{V_u} - \dfrac{l_w}{2}\right)$ is negative, Eq. 6.6.69 shall not apply.
#### 6.4.8.7
Sections located closer to wall base than a distance $\dfrac{l_w}{2}$ or one-half the wall height, whichever is less, shall be permitted to be designed for the same $V_c$ as that computed at a distance $\dfrac{l_w}{2}$ or one-half the height.
#### 6.4.8.8
Where $V_u$ is less than 0.5$\phi V_c$, reinforcement shall be provided in accordance with Sec 6.4.8.9 or in accordance with Sec. 6.6. Where $V_u$ exceeds 0.5$\phi V_c$, wall reinforcement for resisting shear shall be provided in accordance with Sec 6.4.8.9.
#### 6.4.8.9 Design of shear reinforcement for walls
##### 6.4.8.9.1
Where $V_u$ exceeds $\phi V_c$, horizontal shear reinforcement shall be provided to satisfy Equations 6.6.47 and 6.6.48, where $V_s$ shall be computed by
$$
V_s = \frac{A_v f_y d}{s} \tag{6.6.70}
$$
Where, $A_v$ is area of horizontal shear reinforcement within spacing $s$, and $d$ is determined in accordance with Sec 6.4.8.4. Vertical shear reinforcement shall be provided in accordance with Sec 6.4.8.9.4.
##### 6.4.8.9.2
Ratio of horizontal shear reinforcement area to gross concrete area of vertical section, $\rho_t$ shall not be less than 0.0025.
##### 6.4.8.9.3
Spacing of horizontal shear reinforcement shall not exceed the smallest of $\dfrac{l_w}{5}$, $3h$, and 450 mm, where $l_w$ is the overall length of the wall.
##### 6.4.8.9.4
Ratio of vertical shear reinforcement area to gross concrete area of horizontal section, $\rho_l$ shall not be less than the larger of 0.0025 and the value obtained from:
$$
\rho_l = 0.0025 + 0.5\left(2.5 - \frac{h_w}{l_w}\right)(\rho_t - 0.0025) \tag{6.6.71}
$$
The value of $\rho_l$ calculated by Eq. 6.6.71 need not be greater than $\rho_t$ required by Sec 6.4.8.9.1. In Eq. 6.6.71, $l_w$ is the overall length of the wall, and $h_w$ is the overall height of the wall.
##### 6.4.8.9.5
Spacing of vertical shear reinforcement shall not exceed the smallest of $\dfrac{l_w}{3}$, $3h$, and 450 mm, where $l_w$ is the overall length of the wall.
### **6.4.9 Transfer of Moments to Columns**
#### 6.4.9.1
When gravity load, wind, earthquake, or other lateral forces cause transfer of moment at connections of framing elements to columns, the shear resulting from moment transfer shall be considered in the design of lateral reinforcement in the columns.
#### 6.4.9.2
Except for connections not part of a primary seismic load-resisting system that are restrained on four sides by beams or slabs of approximately equal depth, connections shall have lateral reinforcement not less than that required by Eq. 6.6.55 within the column for a depth not less than that of the deepest connection of framing elements to the columns. See also Sec. 8.1.13 Chapter 8.
### 6.4.10 Provisions for Footings and Slabs
#### 6.4.10.1
The shear strength of footings and slabs in the vicinity of columns, concentrated loads, or reactions is governed by the more severe of the following two conditions:
##### 6.4.10.1.1
Beam action where each critical section to be investigated extends in a plane across the entire width. The slab or footing shall be designed in accordance with Sections 6.4.1 to 6.4.3 for beam action.
##### 6.4.10.1.2
For two-way action, each of the critical sections to be investigated shall be located so that its perimeter *bo* is a minimum but need not approach closer
thand to: 2
* (a) Edges or corners of columns, concentrated loads, or reaction areas; and
* (b) Changes in slab thickness such as edges of capitals, drop panels, or shear caps.
For two-way action, the slab or footing shall be designed in accordance with Sections 6.4.10.2 to 6.4.10.6.
##### 6.4.10.1.3
For square or rectangular columns, concentrated loads, or reaction areas, the critical sections with four straight sides shall be permitted.
#### 6.4.10.2
For two-way action, the design of a slab or footing is based on Equations 6.6.47 and 6.6.48. $V_c$ shall be computed in accordance with Sec 6.4.10.2.1, or Sec 6.4.10.3.1. $V_s$ shall be computed in accordance with 6.4.10.3. For slabs with shearheads, $V_n$ shall be in accordance with Sec 6.4.10.4. Where moment is transferred between a slab and a column, Sec 6.4.10.6 shall apply.
##### 6.4.10.2.1
For slabs and footings, $V_c$ shall be the smallest of the values given by Equations 6.6.72, 6.6.73 and 6.6.74:
$$
V_c = 0.17\left(1 + \frac{2}{\beta}\right)\lambda\sqrt{f_c'}b_od \tag{6.6.72}
$$
Where, β is the ratio of long side to short side of the column, concentrated load or reaction area;
$$
V_c = 0.083\left(\frac{\alpha_sd}{b_o} + 2\right)\lambda\sqrt{f_c'}b_od \tag{6.6.73}
$$
Where, $\alpha_s$ is 40 for interior columns, 30 for edge columns, 20 for corner columns; and
$$
V_c = 0.33\lambda\sqrt{f_c'}b_od \tag{6.6.74}
$$
#### 6.4.10.3
Bars or wires and single- or multiple-leg stirrups as shear reinforcement shall be permitted in slabs and footings with $d$ greater than or equal to 150 mm, but not less than 16 times the shear reinforcement bar diameter. Shear reinforcement shall be in accordance with Sections 6.4.10.3.1 to 6.4.10.3.4.
##### 6.4.10.3.1
For computing $V_n$, Eq. 6.6.48 shall be used and $V_c$ shall not be taken greater than $0.17\lambda\sqrt{f_c'}bd$ and $V_s$ shall be calculated in accordance with Sec 6.4.3. In Eq. 6.6.56, $A_v$ shall be taken as the cross-sectional area of all legs of reinforcement on one peripheral line that is geometrically similar to the perimeter of column section.
##### 6.4.10.3.2
$V_n$ shall not be taken greater than $0.5\sqrt{f_c'}bd$.
##### 6.4.10.3.3
The distance from the column face to the first line of stirrup legs that surround the column shall not exceed $d/2$. The spacing between adjacent stirrups legs in the first line of shear reinforcement shall not exceed 2$d$ measured in a direction parallel to the column face. The spacing between successive lines of shear reinforcement that surround the column shall not exceed $d/2$ measured in a direction perpendicular to the column face. In a slab-column connection for which the moment transfer is negligible, the shear reinforcement should be symmetrical about the centroid of the critical section Figure 6.6.14. Spacing limits defined above are also shown in Figure 6.6.14 for interior column and in Figure 6.6.15 for edge column. At edge columns or for interior connections where moment transfer is significant, closed stirrups are recommended in a pattern as symmetrical as possible.
![Plan and elevation arrangement of stirrup shear reinforcement around an interior column]()
![Plan and elevation arrangement of stirrup shear reinforcement around an edge column]()
##### 6.4.10.3.4
Slab shear reinforcement shall satisfy the anchorage requirements of Sec 8.2.10 Chapter 8 and shall engage the longitudinal flexural reinforcement in the direction being considered.
#### 6.4.10.4
Shear reinforcement consisting of structural steel I- or channel-shaped sections (shearheads) shall be permitted in slabs. The provisions of Sections 6.4.10.4.1 to 6.4.10.4.9 shall apply where shear due to gravity load is transferred at interior column supports. Where moment is transferred to columns, Sec 6.4.10.7.3 shall apply.
##### 6.4.10.4.1
Each shearhead shall consist of steel shapes fabricated by welding with a full penetration weld into identical arms at right angles. Shearhead arms shall not be interrupted within the column section.
##### 6.4.10.4.2
A shearhead shall not be deeper than 70 times the web thickness of the steel shape.
##### 6.4.10.4.3
The ends of each shearhead arm shall be permitted to be cut at angles not less than 30 degrees with the horizontal, provided the plastic moment strength of the remaining tapered section is adequate to resist the shear force attributed to that arm of the shearhead.
##### 6.4.10.4.4
All compression flanges of steel shapes shall be located within 0.3 *d* of compression surface of slab.
##### 6.4.10.4.5
The ratio $\alpha_v$ between the flexural stiffness of each shearhead arm and that of the surrounding composite cracked slab section of width $(c_2 + d)$ shall not be less than 0.15.
##### 6.4.10.4.6
Plastic moment strength, $M_p$, required for each arm of the shearhead shall be computed by
$$
M_p = \frac{V_u}{2\phi n}\left[h_v + \alpha_v\left(l_v - \frac{c_1}{2}\right)\right] \tag{6.6.75}
$$
Where, $\phi$ is for tension-controlled members, $n$ is number of shearhead arms, and $l_v$ is minimum length of each shearhead arm required to comply with requirements of Sections 6.4.10.4.7 and 6.4.10.4.8.
##### 6.4.10.4.7
The critical slab section for shear shall be perpendicular to the plane of the slab and shall cross each shearhead arm at three-quarters the distance $\left[l_v - \left(\frac{c_1}{2}\right)\right]$ from the column face to the end of the shearhead arm. The critical section shall be located so that its perimeter $b_o$ is a minimum, but need not be closer than the perimeter defined in Sec 6.4.10.1.2(a).
##### 6.4.10.4.8
$V_n$ shall not be taken larger than $0.33\sqrt{f_c'}b_od$ on the critical section defined in Sec 6.4.10.4.7. When shearhead reinforcement is provided, $V_n$ shall not be taken greater than $0.58\sqrt{f_c'}b_od$ on the critical section defined in Sec 6.4.10.1.2(a).
##### 6.4.10.4.9
Moment resistance $M_v$ contributed to each slab column strip by a shearhead shall not be taken greater than
$$
M_v = \frac{\phi\alpha_vV_u}{2n}\left(l_v - \frac{c_1}{2}\right) \tag{6.6.76}
$$
Where, $\phi$ is for tension-controlled members, $n$ is number of shearhead arms, and $l_v$ is length of each shearhead arm actually provided. However, $M_v$ shall not be taken larger than the smallest of:
* (a) 30 percent of the total factored moment required for each slab column strip;
* (b) The change in column strip moment over the length $l_v$;
* (c) $M_p$ computed by Eq. 6.6.75.
##### 6.4.10.4.10
When unbalanced moments are considered, the shearhead must have adequate anchorage to transmit *M p* to the column.
#### 6.4.10.5
Headed shear stud reinforcement, placed perpendicular to the plane of a slab or footing, shall be permitted in slabs and footings in accordance with 6.4.10.5.1 through 6.4.10.5.4. The overall height of the shear stud assembly shall not be less than the thickness of the member less the sum of: (1) the concrete cover on the top flexural reinforcement; (2) the concrete cover on the base rail; and (3) one-half the bar diameter of the tension flexural reinforcement. Where flexural tension reinforcement is at the bottom of the section, as in a footing, the overall height of the shear stud assembly shall not be less than the thickness of the member less the sum of: (1) the concrete cover on the bottom flexural reinforcement; (2) the concrete cover on the head of the stud; and (3) one-half the bar diameter of the bottom flexural reinforcement.
##### 6.4.10.5.1
For the critical section defined in Sec 6.4.10.1.2, $V_n$ shall be computed using Eq. 6.6.48, with $V_c$ and $V_n$ not exceeding $0.25\lambda\sqrt{f_c'}\,b_od$ and $0.66\lambda\sqrt{f_c'}\,b_od$ respectively. $V_s$ shall be calculated using Eq. 6.6.56 with $A_v$ equal to the cross-sectional area of all the shear reinforcement on one peripheral line that is approximately parallel to the perimeter of the column section, where $s$ is the spacing of the peripheral lines of headed shear stud reinforcement. $\dfrac{A_v f_{yt}}{b_os}$ shall not be less than $0.17\sqrt{f_c'}$
##### 6.4.10.5.2
The spacing between the column face and the first peripheral line of shear reinforcement shall not exceed $\dfrac{d}{2}$. The spacing between peripheral lines of shear reinforcement, measured in a direction perpendicular to any face of the column, shall be constant. For all slabs and footings, the spacing shall be based on the value of the shear stress due to factored shear force and unbalanced moment at the critical section defined in Sec 6.4.10.1.2, and shall not exceed:
* (a) $0.75d$, where maximum shear stresses due to factored loads are less than or equal to $0.5\phi\sqrt{f_c'}$; and
* (b) $0.5d$, where maximum shear stresses due to factored loads are greater than $0.5\phi\sqrt{f_c'}$.
##### 6.4.10.5.3
The spacing between adjacent shear reinforcement elements, measured on the perimeter of the first peripheral line of shear reinforcement, shall not exceed $2d$.
##### 6.4.10.5.4
Shear stress due to factored shear force and moment shall not exceed $0.17\phi\lambda\sqrt{f_c'}$ at the critical section located $\dfrac{d}{2}$ outside the outermost peripheral line of shear reinforcement.
#### 6.4.10.6 Openings in slabs
If openings in slabs are located at a distance less than 10 times the slab thickness from a concentrated load or reaction area, or when openings in flat slabs are located within column strips as defined in Sec. 6.5, the critical slab sections for shear defined in Sections 6.4.10.1.2 and 6.4.10.4.7 shall be modified as follows:
##### 6.4.10.6.1
For slabs without shearheads, that part of the perimeter of the critical section that is enclosed by straight lines projecting from the centroid of the column, concentrated load, or reaction area and tangent to the boundaries of the openings shall be considered ineffective Figure 6.6.16.
##### 6.4.10.6.2
For slabs with shearheads, the ineffective portion of the perimeter shall be one-half of that defined in Sec 6.4.10.6.1.
![Effective critical shear perimeter considering the effect of openings and free edges near columns]()
#### 6.4.10.7 Transfer of moment in slab-column connections
##### 6.4.10.7.1
Where gravity load, wind, earthquake, or other lateral forces cause transfer of unbalanced moment $M_u$ between a slab and column, $\gamma_f M_u$ shall be transferred by flexure in accordance with Sec 6.5.5.3. The remainder of the unbalanced moment, $\gamma_v M_u$, shall be considered to be transferred by eccentricity of shear about the centroid of the critical section defined in Sec 6.4.10.1.2 where
$$
\gamma_v = (1 - \gamma_f) \tag{6.6.77}
$$
##### 6.4.10.7.2
The shear stress resulting from moment transfer by eccentricity of shear shall be assumed to vary linearly about the centroid of the critical sections defined in Sec 6.4.10.1.2. The maximum shear stress due to $V_u$ and $M_u$ shall not exceed $\phi v_n$:
* (a) For members without shear reinforcement,
$$
\phi V_n = \phi V_c/(b_od) \tag{6.6.78}
$$
Where, $V_c$ is as defined in Sec 6.4.10.2.1.
* (b) For members with shear reinforcement other than shearheads,
$$
\phi V_n = \phi (V_c + V_s)/(b_od) \tag{6.6.79}
$$
Where, $V_c$ and $V_s$ are defined in Sec 6.4.10.3.1. The design shall take into account the variation of shear stress around the column. The shear stress due to factored shear force and moment shall not exceed $\left(0.17\phi\lambda\sqrt{f_c'}\right)$ at the critical section located $d/2$ outside the outermost line of stirrup legs that surround the column.
The maximum factored shear stress may be obtained from the combined shear stresses on the left and right faces of the column (Figure 6.6.17) as given by the following Equations:
$$
v_l = \frac{V_u}{A_c} - \frac{\gamma_v M_u c_l}{J_c} \tag{6.6.80a}
$$
$$
v_r = \frac{V_u}{A_c} + \frac{\gamma_v M_u c_r}{J_c} \tag{6.6.80b}
$$
Where, $A_c$ = area of concrete of assumed critical section = $2d(c_1 + c_2 + 2d)$
$c_l$, $c_r$ = distances from centroid of critical section to left and right face of section respectively
$c_1$, $c_2$ = width and depth of the column
$J_c$ = property of assumed critical section analogous to polar moment of inertia. For an interior column, the quantity $J_c$ is
$$
J_c = \frac{2d(c_1+d)^3}{12} + \frac{2(c_1+d)d^3}{12} + 2d(c_2+d)\left(\frac{c_1+d}{2}\right)^2 \tag{6.6.80c}
$$
##### 6.4.10.7.3
When shear reinforcement consisting of structural steel I- or channelshaped sections (shearheads) is provided, the sum of the shear stresses due to vertical load acting on the critical section defined by Sec 6.4.10.4.7 and the shear stresses resulting from moment transferred by eccentricity of shear about the centroid of the critical section defined in Sec 6.4.10.1.2(a) and 6.4.10.1.3 shall not exceed $0.33\phi\lambda\sqrt{f_c'}$.
![Transfer of moment from slab to column with critical shear sections and stress distributions for interior and edge columns]()
## **6.5 Two-Way Slab Systems: Flat Plates, Flat Slabs and Edge-Supported Slabs**
### **6.5.1 Scope**
The provisions of this section shall apply to all slabs, solid, ribbed or hollow, spanning in more than one direction, with or without beams between the supports. Flat plate is a term normally attributed to slabs without beams and without drop panels, column capitals, or brackets. On the other hand, slabs without beams, but with drop panels, column capital or brackets are commonly known as flat slabs. While this section covers the requirements for all types of slabs, the provisions of Sec 6.5.8. Alternative Design of Two-way Edge-Supported slabs, may be used as an alternative for slabs supported on all four edges by walls, steel beams or monolithic concrete beams having a total depth not less than 3 times the slab thickness.
#### 6.5.1.1
For a slab system supported by columns or walls, dimensions $, $q, and $l_n$ shall be based on an effective support area defined by the intersection of the bottom surface of the slab, or of the drop panel or shear cap if present, with the largest right circular cone, right pyramid, or tapered wedge whose surfaces are located within the column and the capital or bracket and are oriented no greater than 45o to the axis of the column.
#### 6.5.1.2
Minimum thickness of slabs designed in accordance with Sec. 6.5 shall be as required by Sec 6.2.5.3.
### **6.5.2 General**
#### 6.5.2.1
Column strip is a design strip with a width on each side of a column centerline equal to 0.25$l_n$ or 0.25$l$, whichever is less. Column strip includes beams, if any.
#### 6.5.2.2
Middle strip is a design strip bounded by two column strips.
#### 6.5.2.3
A panel is bounded by column, beam, or wall centerlines on all sides.
#### 6.5.2.4
For monolithic or fully composite construction, a beam includes that portion of slab on each side of the beam extending a distance equal to the projection of the beam above or below the slab, whichever is greater, but not greater than four times the slab thickness (Figure 6.6.18).
#### 6.5.2.5
When used to reduce the amount of negative moment reinforcement over a column or minimum required slab thickness, a drop panel shall:
* (a) project below the slab at least one-quarter of the adjacent slab thickness; and
* (b) extend in each direction from the centerline of support a distance not less than one-sixth the span length measured from center-to-center of supports in that direction.
When used to increase the critical condition section for shear at a slab-column joint, a shear cap shall project below the slab and extend a minimum horizontal distance from the face of the column that is equal to the thickness of the projection below the slab soffit.
![Portion of slab to be included with the beam for monolithic or composite construction]()
### **6.5.3 Slab Reinforcement**
#### 6.5.3.1
Area of reinforcement in each direction for two-way slab systems shall be determined from moments at critical sections, but shall not be less than required by Sec. 8.1.11.2 Chapter 8.
#### 6.5.3.2
Spacing of reinforcement at critical sections shall not exceed two times the slab thickness, except for portions of slab area of cellular or ribbed construction. In the slab over cellular spaces, reinforcement shall be provided as required by Sec. 8.1.11 Chapter 8.
#### 6.5.3.3
Positive moment reinforcement perpendicular to a discontinuous edge shall extend to the edge of slab and have embedment, straight or hooked, at least 150 mm in spandrel beams, columns, or walls.
#### 6.5.3.4
Negative moment reinforcement perpendicular to a discontinuous edge shall be bent, hooked, or otherwise anchored in spandrel beams, columns, or walls, and shall be developed at face of support according to provisions of Sec. 8.2 Chapter 8.
#### 6.5.3.5
Where a slab is not supported by a spandrel beam or wall at a discontinuous edge, or where a slab cantilevers beyond the support, anchorage of reinforcement shall be permitted within the slab.
#### 6.5.3.6
At exterior corners of slabs supported by edge walls or where one or more edge beams have a value of u\` greater than 1.0, top and bottom slab reinforcement shall be provided at exterior corners in accordance with Sections 6.5.3.6.1 to 6.5.3.6.4 and as shown in Figure 6.6.19.
##### 6.5.3.6.1
Corner reinforcement in both top and bottom of slab shall be sufficient to resist a moment per unit of width equal to the maximum positive moment per unit width in the slab panel.
##### 6.5.3.6.2
The moment shall be assumed to be about an axis perpendicular to the diagonal from the corner in the top of the slab and about an axis parallel to the diagonal from the corner in the bottom of the slab.
##### 6.5.3.6.3
Corner reinforcement shall be provided for a distance in each direction from the corner equal to one-fifth the longer span.
##### 6.5.3.6.4
Corner reinforcement shall be placed parallel to the diagonal in the top of the slab and perpendicular to the diagonal in the bottom of the slab. Alternatively, reinforcement shall be placed in two layers parallel to the sides of the slab in both the top and bottom of the slab.
![Top and bottom corner reinforcement layout options Choice-1 and Choice-2 in two-way slabs]()
#### 6.5.3.7
When a drop panel is used to reduce the amount of negative moment reinforcement over the column of a flat slab, the dimensions of the drop panel shall be in accordance with Sec 6.5.2.5. In computing required slab reinforcement, the thickness of the drop panel below the slab shall not be assumed to be greater than one-quarter the distance from the edge of drop panel to the face of column or column capital.
#### 6.5.3.8 Details of reinforcement in slabs without beams
##### 6.5.3.8.1
In addition to the other requirements of Sec 6.5.3, reinforcement in slabs without beams shall have minimum extensions as prescribed in Figure 6.6.20.
##### 6.5.3.8.2
Where adjacent spans are unequal, extensions of negative moment reinforcement beyond the face of support as prescribed in Figure 6.6.20 shall be based on requirements of the longer span.
##### 6.5.3.8.3
Bent bars shall be permitted only when depth-span ratio permits use of bends of 45 degrees or less.
##### 6.5.3.8.4
In frames where two-way slabs act as primary members resisting lateral loads, lengths of reinforcement shall be determined by analysis but shall not be less than those prescribed in Figure 6.6.20.
##### 6.5.3.8.5
All bottom bars or wires within the column strip, in each direction, shall be continuous or spliced with Class B tension splices or with mechanical or welded splices satisfying Sec. 8.2.12.3 Chapter 8. Splices shall be located as shown in Figure 6.6.20. At least two of the column strip bottom bars or wires in each direction shall pass within the region bounded by the longitudinal reinforcement of the column and shall be anchored at exterior supports.
##### 6.5.3.8.6
In slabs with shearheads and in lift-slab construction where it is not practical to pass the bottom bars required by 6.5.3.8.5 through the column, at least two bonded bottom bars or wires in each direction shall pass through the shearhead or lifting collar as close to the column as practicable and be continuous or spliced with a Class A splice. At exterior columns, the reinforcement shall be anchored at the shearhead or lifting collar.
![Minimum extensions and bar cutoff details for reinforcement in slabs without beams]()
### **6.5.4 Openings in Slab Systems**
#### 6.5.4.1
Openings of any size shall be permitted in slab systems if shown by analysis that the design strength is at least equal to the required strength set forth in Sections 6.2.2 and 6.2.3, and that all serviceability conditions, including the limits on deflections, are met.
#### 6.5.4.2
As an alternate to analysis required by Sec 6.5.4.1, openings shall be permitted in slab systems without beams only, in accordance with Sections 6.5.4.2.1 to 6.5.4.2.4.
##### 6.5.4.2.1
Openings of any size shall be permitted in the area common to intersecting middle strips, provided total amount of reinforcement required for the panel without the opening is maintained.
##### 6.5.4.2.2
In the area common to intersecting column strips, not more than oneeighth the width of column strip in either span shall be interrupted by openings. An amount of reinforcement equivalent to that interrupted by an opening shall be added on the sides of the opening.
##### 6.5.4.2.3
In the area common to one column strip and one middle strip, not more than one-quarter of the reinforcement in either strip shall be interrupted by openings. An amount of reinforcement equivalent to that interrupted by an opening shall be added on the sides of the opening.
##### 6.5.4.2.4
Shear requirements of Sec 6.4.10.6 shall be satisfied.
### **6.5.5 Design Procedures**
#### 6.5.5.1
A slab system shall be designed by any procedure satisfying conditions of equilibrium and geometric compatibility, if shown that the design strength at every section is at least equal to the required strength set forth in Sections 6.2.2 and 6.2.3, and that all serviceability conditions, including limits on deflections, are met.
##### 6.5.5.1.1
Design of a slab system for gravity loads, including the slab and beams (if any) between supports and supporting columns or walls forming orthogonal frames, by either the Direct Design Method of Sec 6.5.6 or the Equivalent Frame Method of Sec 6.5.7, shall be permitted.
##### 6.5.5.1.2
For lateral loads, analysis of frames shall take into account effects of cracking and reinforcement on stiffness of frame members.
##### 6.5.5.1.3
Combining the results of the gravity load analysis with the results of the lateral load analysis shall be permitted.
#### 6.5.5.2
The slab and beams (if any) between supports shall be proportioned for factored moments prevailing at every section.
#### 6.5.5.3
When gravity load, wind, earthquake, or other lateral forces cause transfer of moment between slab and column, a fraction of the unbalanced moment shall be transferred by flexure in accordance with Sections 6.5.5.3.2 to 6.5.5.3.4.
##### 6.5.5.3.1
The fraction of unbalanced moment not transferred by flexure shall be transferred by eccentricity of shear in accordance with Sec 6.4.10.7.
##### 6.5.5.3.2
A fraction of the unbalanced moment given by $\gamma_fM_u$ shall be considered to be transferred by flexure within an effective slab width between lines that are one and one-half slab or drop panel thickness (1.5 *h* ) outside opposite faces of the column or capital, where *M u* is the factored moment to be transferred and
$$
\gamma_f = \frac{1}{1+(2/3)\sqrt{b_1/b_2}} \tag{6.6.81}
$$
##### 6.5.5.3.3
For slabs with unbalanced moments transferred between the slab and columns, it shall be permitted to increase the value of γ *f* given by Eq. 6.6.81 in accordance with the following:
* (a) For edge columns with unbalanced moments about an axis parallel to the edge, $\gamma_f$ = 1.0 provided that $V_u$ at an edge support does not exceed 0.75$\phi V_c$, or at a corner support does not exceed 0.5$\phi V_c$.
* (b) For unbalanced moments at interior supports, and for edge columns with unbalanced moments about an axis perpendicular to the edge, increase $\gamma_f$ to as much as 1.25 times the value from Eq. 6.6.81, but not more than $\gamma_f$ = 1.0, provided that $V_u$ at the support does not exceed 0.4$\phi V_c$. The net tensile strain $\varepsilon_t$ calculated for the effective slab width defined in Sec 6.5.5.3.2 shall not be less than 0.010.
The value of $V_c$ in items (a) and (b) shall be calculated in accordance with Sec 6.4.10.2.1.
##### 6.5.5.3.4
Concentration of reinforcement over the column by closer spacing or additional reinforcement shall be used to resist moment on the effective slab width defined in Sec 6.5.5.3.2.
#### 6.5.5.4
Design for transfer of load from slabs to supporting columns or walls through shear and torsion shall be in accordance with Sec. 6.4.
### 6.5.6 Direct Design Method
#### 6.5.6.1 Limitations
Design of slab systems within the limitations of Sections 6.5.6.1.1 to 6.5.6.1.8 by the direct design method shall be permitted.
##### 6.5.6.1.1
There shall be a minimum of three continuous spans in each direction.
##### 6.5.6.1.2
Panels shall be rectangular, with a ratio of longer to shorter span centerto-center of supports within a panel not greater than 2.
##### 6.5.6.1.3
Successive span lengths center-to-center of supports in each direction shall not differ by more than one-third the longer span.
##### 6.5.6.1.4
Offset of columns by a maximum of 10 percent of the span (in direction of offset) from either axis between centerlines of successive columns shall be permitted.
##### 6.5.6.1.5
All loads shall be due to gravity only and uniformly distributed over an entire panel. The unfactored live load shall not exceed two times the unfactored dead load.
##### 6.5.6.1.6
For a panel with beams between supports on all sides, Eq. 6.6.82 shall be satisfied for beams in the two perpendicular directions.
$$
0.2 \leq \frac{\alpha_{f1}l_2^2}{\alpha_{f2}l_1^2} \leq 5.0 \tag{6.6.82}
$$
Where, $\alpha_{f1}$ and $\alpha_{f2}$ are calculated using respective stiffness parameters in accordance with the general Equation 6.6.83.
$$
\alpha_f = \frac{E_{cb}I_b}{E_{cs}I_s} \tag{6.6.83}
$$
##### 6.5.6.1.7
Moment redistribution as permitted by Sec 6.1.6 shall not be applied for slab systems designed by the direct design method. See Sec 6.5.6.7.
##### 6.5.6.1.8
Variations from the limitations of Sec 6.5.6.1 shall be permitted if demonstrated by analysis that requirements of Sec 6.5.5.1 are satisfied.
#### 6.5.6.2 Total factored static moment for a span
##### 6.5.6.2.1
Total factored static moment, *M o* , for a span shall be determined in a strip bounded laterally by centerline of panel on each side of centerline of supports.
##### 6.5.6.2.2
Absolute sum of positive and average negative factored moments in each direction shall not be less than
$$
M_o = \frac{q_ul_2l_n^2}{8} \tag{6.6.84}
$$
Where, $l_n$ is length of clear span in direction that moments are being determined.
##### 6.5.6.2.3
Where the transverse span of panels on either side of the centerline of supports varies, *l2* in Eq. 6.6.84 shall be taken as the average of adjacent transverse spans.
##### 6.5.6.2.4
When the span adjacent and parallel to an edge is being considered, the distance from edge to panel centerline shall be substituted for *l2* in Eq. 6.6.84.
##### 6.5.6.2.5
Clear span*l* *n*shall extend from face to face of columns, capitals,
brackets, or walls. Value of*l* *n*used in Eq. 6.6.84 shall not be less than 0.65 *l1* . Circular or regular polygon-shaped supports shall be treated as square supports with the same area.
#### 6.5.6.3 Negative and positive factored moments
##### 6.5.6.3.1
Negative factored moments shall be located at face of rectangular supports. Circular or regular polygon-shaped supports shall be treated as square supports with the same area.
##### 6.5.6.3.2
In an interior span, total static moment, *M o* , shall be distributed as follows:
Negative factored moment: 0.65 Positive factored moment: 0.35
##### 6.5.6.3.3
In an end span, total factored static moment, *M o* , shall be distributed as in Table 6.6.4 below:
Table 6.6.4: Distribution of Total Factored Static Moment, *M o* in an End Span
| Moments | Exterior edge
unrestrained | Slab with
beams | Slab without be
interior su | ams between
pports |
Exterior
edge fully |
| -------------------------------------- | ------------------------------- | ------------------------- | -------------------------------- | ----------------------- | ------------------------------ |
| | | between all
supports | Without edge
beam | With edge
beam | restrained |
| Interior negative
factored moment | 0.75 | 0.70 | 0.70 | 0.70 | 0.65 |
| Positive factored
moment | 0.63 | 0.57 | 0.52 | 0.50 | 0.35 |
| Exterior negative
factored moment | 0 | 0.16 | 0.26 | 0.30 | 0.65 |
##### 6.5.6.3.4
Negative moment sections shall be designed to resist the larger of the two interior negative factored moments determined for spans framing into a common support unless an analysis is made to distribute the unbalanced moment in accordance with stiffnesses of adjoining elements.
##### 6.5.6.3.5
Edge beams or edges of slab shall be proportioned to resist in torsion their share of exterior negative factored moments.
##### 6.5.6.3.6
The gravity load moment to be transferred between slab and edge column in accordance with 6.5.5.3.1 shall be $0.3M_o$.
#### 6.5.6.4 Factored moments in column strips
##### 6.5.6.4.1
Column strips shall be proportioned to resist the portions in percent of interior negative factored moments as shown in Table 6.6.5.
##### 6.5.6.4.2
Column strips shall be proportioned to resist the portions in percent of exterior negative factored moments as shown in Table 6.6.6.
Table 6.6.5: Portions of Interior Negative Moments to be resisted by Column Strip
|Parameters|$l_2/l_1$||
\|---|---|---|---|
||0.5|1.0|2.0|
|$\left(\dfrac{\alpha_{f1}l_2}{l_1}\right) = 0$|75|75|75|
|$\left(\dfrac{\alpha_{f1}l_2}{l_1}\right) \geq 1$|90|75|45|
Notes: Linear interpolations shall be made between values shown.
Interpolation function for % of Moment $= 75 + 30\left(\dfrac{\alpha_{f1}l_2}{l_1}\right)\left(1 - \dfrac{l_2}{l_1}\right)$
Table 6.6.6: Portions of Exterior Negative Moments to be resisted by Column Strip
|Parameters||$l_2/l_1$||
\|---|---|---|---|---|
|||0.5|1.0|2.0|
|$\left(\dfrac{\alpha_{f1}l_2}{l_1}\right) = 0$|$\beta_t=0$|100|100|100|
||$\beta_t \geq 2.5$|75|75|75|
|$\left(\dfrac{\alpha_{f1}l_2}{l_1}\right) \geq 1$|$\beta_t=0$|100|100|100|
||$\beta_t \geq 2.5$|90|75|45|
Linear interpolations shall be made between values shown, where $\beta_t$ is calculated in Eq. 6.6.85 and $C$ is calculated in Eq. 6.6.86.
$$
\beta_t = \frac{E_{cb}C}{2E_{cs}I_s} \tag{6.6.85}
$$
$$
C = \sum\left(1 - 0.63\frac{x}{y}\right)\frac{x^3y}{3} \tag{6.6.86}
$$
The constant $C$ for *T* or *L* sections shall be permitted to be evaluated by dividing the section into separate rectangular parts, as defined in Sec 6.5.2.4, and summing the values of $C$ for each part.
Interpolation function for % of Moment $= 100 - 10\beta_t + 12\beta_t\left(\dfrac{\alpha_{f1}l_2}{l_1}\right)\left(1 - \dfrac{l_2}{l_1}\right)$
##### 6.5.6.4.3
Where supports consist of columns or walls extending for a distance equal to or greater than 0.75*l* *2* used to compute *M o* , negative moments shall be considered to be uniformly distributed across*l* *2* .
##### 6.5.6.4.4
Column strips shall be proportioned to resist the portions in percent of positive factored moments shown in Table 6.6.7.
##### 6.5.6.4.5
For slabs with beams between supports, the slab portion of column strips shall be proportioned to resist that portion of column strip moments not resisted by beams.
Table 6.6.7: Portions of Positive Moment to be resisted by Column Strip
|Parameters|$l_2/l_1$||
\|---|---|---|---|
||0.5|1.0|2.0|
|$\left(\dfrac{\alpha_{f1}l_2}{l_1}\right) = 0$|60|60|60|
|$\left(\dfrac{\alpha_{f1}l_2}{l_1}\right) \geq 1$|90|75|45|
Notes: Linear interpolations shall be made between values shown.
Interpolation function for % of Moment $= 60 + 30\left(\dfrac{\alpha_{f1}l_2}{l_1}\right)\left(1.5 - \dfrac{l_2}{l_1}\right)$
#### 6.5.6.5 Factored moments in beams
##### 6.5.6.5.1
Beams between supports shall be proportioned to resist 85 percent of column strip moments if *α f* 1 *l* 2*/l* 1 is equal to or greater than 1.0.
##### 6.5.6.5.2
For values of *α f* 1 *l* 2*/l* 1 between 1.0 and zero, proportion of column strip moments resisted by beams shall be obtained by linear interpolation between 85 and zero percent.
##### 6.5.6.5.3
In addition to moments calculated for uniform loads according to Sections 6.5.6.2.2, 6.5.6.5.1, and 6.5.6.5.2, beams shall be proportioned to resist all moments caused by concentrated or linear loads applied directly to beams, including weight of projecting beam stem above or below the slab.
#### 6.5.6.6 Factored moments in middle strips
##### 6.5.6.6.1
That portion of negative and positive factored moments not resisted by column strips shall be proportionately assigned to corresponding half middle strips.
##### 6.5.6.6.2
Each middle strip shall be proportioned to resist the sum of the moments assigned to its two half middle strips.
##### 6.5.6.6.3
A middle strip adjacent to and parallel with a wall-supported edge shall be proportioned to resist twice the moment assigned to the half middle strip corresponding to the first row of interior supports.
#### 6.5.6.7 Modification of factored moments
Modification of negative and positive factored moments by 10 percent shall be permitted provided the total static moment for a panel, po, in the direction considered is not less than that required by Eq. 6.6.84.
#### 6.5.6.8 Factored shear in slab systems with beams
##### 6.5.6.8.1
Beams with *α f* 1 *l* 2*/l* 1 equal to or greater than 1.0 shall be proportioned to resist shear caused by factored loads on tributary areas which are bounded by 45o lines drawn from the corners of the panels and the centerlines of the adjacent panels parallel to the long sides (Figure 6.6.21).
![Tributary area bounded by 45 degree lines for shear on an interior beam in two-way slab system]()
##### 6.5.6.8.2
In proportioning beams with *α f* 1 *l* 2*/l* 1 less than 1.0 to resist shear, linear interpolation, assuming beams carry no load at*α* *f* 1= 0, shall be permitted.
##### 6.5.6.8.3
In addition to shears calculated according to Sections 6.5.6.8.1 and 6.5.6.8.2, beams shall be proportioned to resist shears caused by factored loads applied directly on beams.
##### 6.5.6.8.4
Computation of slab shear strength on the assumption that load is distributed to supporting beams in accordance with Sec 6.5.6.8.1 or Sec 6.5.6.8.2 shall be permitted. Resistance to total shear occurring on a panel shall be provided.
##### 6.5.6.8.5
Shear strength shall satisfy the requirements of Sec. 6.4.
#### 6.5.6.9 Factored moments in columns and walls
##### 6.5.6.9.1
Columns and walls built integrally with a slab system shall resist moments caused by factored loads on the slab system.
##### 6.5.6.9.2
At an interior support, supporting elements above and below the slab shall resist the factored moment specified by Eq. 6.6.87 in direct proportion to their stiffnesses unless a general analysis is made.
$$
M_u = 0.07\left[(q_{Du} + 0.5q_{Lu})l_2 l_n^2 - q_{Du}'l_2'(l_n')^2\right] \tag{6.6.87}
$$
Where, $q_{Du}'$, $l_2'$, and $l_n'$ refer to shorter span.
### 6.5.7 Equivalent Frame Method
#### 6.5.7.1
Design of slab systems by the equivalent frame method shall be based on assumptions given in Sections 6.5.7.2 to 6.5.7.6, and all sections of slabs and supporting members shall be proportioned for moments and shears thus obtained.
##### 6.5.7.1.1
Where metal column capitals are used, it shall be permitted to take account of their contributions to stiffness and resistance to moment and to shear.
##### 6.5.7.1.2
It shall be permitted to neglect the change in length of columns and slabs due to direct stress, and deflections due to shear.
#### 6.5.7.2 Equivalent frame
##### 6.5.7.2.1
The structure shall be considered to be made up of equivalent frames on column lines taken longitudinally and transversely through the building (Figure 6.6.22).
##### 6.5.7.2.2
Each frame shall consist of a row of columns or supports and slab-beam strips, bounded laterally by the centerline of panel on each side of the center line of columns or supports.
##### 6.5.7.2.3
Columns or supports shall be assumed to be attached to slab-beam strips by torsional members (see Sec 6.5.7.5) transverse to the direction of the span for which moments are being determined and extending to bounding lateral panel centerlines on each side of a column.
##### 6.5.7.2.4
Frames adjacent and parallel to an edge shall be bounded by that edge and the centerline of adjacent panel.
##### 6.5.7.2.5
Analysis of each equivalent frame in its entirety shall be permitted. Alternatively, for gravity loading, a separate analysis of each floor or roof with far ends of columns considered fixed shall be permitted.
##### 6.5.7.2.6
Where slab-beams are analyzed separately, determination of moment at a given support assuming that the slab-beam is fixed at any support two panels distant therefrom, shall be permitted, provided the slab continues beyond that point.
#### 6.5.7.3 Slab-beams
##### 6.5.7.3.1
Determination of the moment of inertia of slab-beams at any cross section outside of joints or column capitals using the gross area of concrete shall be permitted.
##### 6.5.7.3.2
Variation in moment of inertia along axis of slab-beams shall be taken into account.
##### 6.5.7.3.3
Moment of inertia of slab-beams from center of column to face of column, bracket, or capital shall be assumed equal to the moment of inertia of the slab-beam at face of column, bracket, or capital divided by the quantity 2 (1-*c* *2* / *l* 2) where*c* *2*and*l* *2*are measured transverse to the direction of the span for which moments are being determined.
#### 6.5.7.4 Columns
##### 6.5.7.4.1
Determination of the moment of inertia of columns at any cross section outside of joints or column capitals using the gross area of concrete shall be permitted.
##### 6.5.7.4.2
Variation in moment of inertia along axis of columns shall be taken into account (Figure 6.6.23).
##### 6.5.7.4.3
Moment of inertia of columns from top to bottom of the slab-beam at a joint shall be assumed to be infinite.
#### 6.5.7.5 Torsional members
##### 6.5.7.5.1
Torsional members (see Sec 6.5.7.2.3) shall be assumed to have a constant cross section throughout their length consisting of the largest of (a), (b), and (c):
* (a) A portion of slab having a width equal to that of the column, bracket, or capital in the direction of the span for which moments are being determined;
* (b) For monolithic or fully composite construction, the portion of slab specified in (a) plus that part of the transverse beam above and below the slab;
* (c) The transverse beam as defined in Sec 6.5.2.4.
##### 6.5.7.5.2
Where beams frame into columns in the direction of the span for which moments are being determined, the torsional stiffness shall be multiplied by the ratio of the moment of inertia of the slab with such a beam to the moment of inertia of the slab without such a beam.
##### 6.5.7.5.3
Stiffness $K_t$ of the torsional members shall be calculated by the following expression:
$$
K_t = \sum \frac{9E_{cs}C}{l_2(1-c_2/l_2)^3} \tag{6.6.88}
$$
Where, $c_2$ and $l_2$ relate to the transverse span on each side of column.
![Definitions of equivalent frame showing longitudinal and transverse slab-beam strips and columns]()
![Equivalent column model consisting of column above and below plus attached transverse torsional members]()
#### 6.5.7.6 Arrangement of live load
##### 6.5.7.6.1
When the loading pattern is known, the equivalent frame shall be analyzed for that load.
##### 6.5.7.6.2
When the unfactored live load is variable but does not exceed threequarters of the unfactored dead load, or the nature of live load is such that all panels will be loaded simultaneously, it shall be permitted to assume that maximum factored moments occur at all sections with full factored live load on entire slab system.
##### 6.5.7.6.3
For loading conditions other than those defined in Sec 6.5.7.6.2, it shall be permitted to assume that maximum positive factored moment near mid span of a panel occurs with three-quarters of the full factored live load on the panel and on alternate panels; and it shall be permitted to assume that maximum negative factored moment in the slab at a support occurs with three-quarters of the full factored live load on adjacent panels only.
##### 6.5.7.6.4
Factored moments shall be taken not less than those occurring with full factored live load on all panels.
#### 6.5.7.7 Factored moments
##### 6.5.7.7.1
At interior supports, the critical section for negative factored moment (in both column and middle strips) shall be taken at face of rectilinear supports, but not farther away than 0.175 *l* 1 from the center of a column.
##### 6.5.7.7.2
At exterior supports with brackets or capitals, the critical section for negative factored moment in the span perpendicular to an edge shall be taken at a distance from face of supporting element not greater than one-half the projection of bracket or capital beyond face of supporting element.
##### 6.5.7.7.3
Circular or regular polygon-shaped supports shall be treated as square supports with the same area for location of critical section for negative design moment.
##### 6.5.7.7.4
Where slab systems within limitations of Sec 6.5.6.1 are analyzed by the equivalent frame method, it shall be permitted to reduce the resulting computed moments in such proportion that the absolute sum of the positive and average negative moments used in design need not exceed the value obtained from Eq. 6.6.84.
##### 6.5.7.7.5
Distribution of moments at critical sections across the slab-beam strip of each frame to column strips, beams, and middle strips as provided in Sections 6.5.6.4 to 6.5.6.6 shall be permitted if the requirement of Sec 6.5.6.1.6 is satisfied.
### **6.5.8 Alternative Design of Two-Way Edge-Supported Slabs**
#### 6.5.8.1 General
The design method described in this Section shall be based on assumptions given in Sec 6.5.8.2 and 6.5.8.3, and all sections of slabs and supporting members shall be proportioned for moments and shears thus obtained.
#### 6.5.8.2 Scope and limitations
##### 6.5.8.2.1
The provisions of this section may be used as alternative to those of Sections 6.5.1 to 6.5.7 for two-way slabs supported on all four edges by walls, steel beams or monolithic concrete beams having a total depth not less than 3 times the slab thickness.
##### 6.5.8.2.2
Panels shall be rectangular with a longer to shorter centre to centre support span ratio of not greater than 2.
#### 6.5.8.3 Analysis by the Coefficient Method
##### 6.5.8.3.1
The negative moments and dead load and live load positive moments in the two directions shall be computed from Tables 6.6.8, 6.6.9 and 6.6.10 respectively. Shear in the slab and loads on the supporting beams shall be computed from Table 6.6.11.
Table 6.6.8: Coefficients for Negative Moments in Slabs†
$$
M_{a,neg} = C_{a,neg}wl_a^2
$$
$$
M_{b,neg} = C_{b,neg}wl_b^2
$$
Where, $w$ = total uniform dead plus live load per unit area
| Span Ratio, $m = l_a/l_b$ | Moment
Coefficient | Case 1
![Case 1]()
| Case 2
![Case 2]()
| Case 3
![Case 3]()
| Case 4
![Case 4]()
| Case 5
![Case 5]()
| Case 6
![Case 6]()
| Case 7
![Case 7]()
| Case 8
![Case 8]()
| Case 9
![Case 9]()
|
| ------------------------- | ----------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- |
| 1.00 | $C_{a,neg}$ | | 0.045 | | 0.050 | 0.075 | 0.071 | | 0.033 | 0.061 |
| | $C_{b,neg}$ | | 0.045 | 0.076 | 0.050 | | | 0.071 | 0.061 | 0.033 |
| 0.95 | $C_{a,neg}$ | | 0.050 | | 0.055 | 0.079 | 0.075 | | 0.038 | 0.065 |
| | $C_{b,neg}$ | | 0.041 | 0.072 | 0.045 | | | 0.067 | 0.056 | 0.029 |
| 0.90 | $C_{a,neg}$ | | 0.055 | | 0.060 | 0.080 | 0.079 | | 0.043 | 0.068 |
| | $C_{b,neg}$ | | 0.037 | 0.070 | 0.040 | | | 0.062 | 0.052 | 0.025 |
| 0.85 | $C_{a,neg}$ | | 0.060 | | 0.066 | 0.082 | 0.083 | | 0.049 | 0.072 |
| | $C_{b,neg}$ | | 0.031 | 0.065 | 0.034 | | | 0.057 | 0.046 | 0.021 |
| 0.80 | $C_{a,neg}$ | | 0.065 | | 0.071 | 0.083 | 0.086 | | 0.055 | 0.075 |
| | $C_{b,neg}$ | | 0.027 | 0.061 | 0.029 | | | 0.051 | 0.041 | 0.017 |
| 0.75 | $C_{a,neg}$ | | 0.069 | | 0.076 | 0.085 | 0.088 | | 0.061 | 0.078 |
| | $C_{b,neg}$ | | 0.022 | 0.056 | 0.024 | | | 0.044 | 0.036 | 0.014 |
| 0.70 | $C_{a,neg}$ | | 0.074 | | 0.081 | 0.086 | 0.091 | | 0.068 | 0.081 |
| | $C_{b,neg}$ | | 0.017 | 0.050 | 0.019 | | | 0.038 | 0.029 | 0.011 |
| 0.65 | $C_{a,neg}$ | | 0.077 | | 0.085 | 0.087 | 0.093 | | 0.074 | 0.083 |
| | $C_{b,neg}$ | | 0.014 | 0.043 | 0.015 | | | 0.031 | 0.024 | 0.008 |
| 0.60 | $C_{a,neg}$ | | 0.081 | | 0.089 | 0.088 | 0.095 | | 0.080 | 0.085 |
| | $C_{b,neg}$ | | 0.010 | 0.035 | 0.011 | | | 0.024 | 0.018 | 0.006 |
| 0.55 | $C_{a,neg}$ | | 0.084 | | 0.092 | 0.089 | 0.096 | | 0.085 | 0.086 |
| | $C_{b,neg}$ | | 0.007 | 0.028 | 0.008 | | | 0.019 | 0.014 | 0.005 |
| 0.50 | $C_{a,neg}$ | | 0.086 | | 0.094 | 0.090 | 0.097 | | 0.089 | 0.088 |
| | $C_{b,neg}$ | | 0.006 | 0.022 | 0.006 | | | 0.014 | 0.010 | 0.003 |
† A crosshatched edge indicates that the slab continues across, or is fixed at the support; an unmarked edge indicates a support at which torsional resistance is negligible.
Table 6.6.9: Coefficients for Dead Load Positive Moments in Slabs†
$$
M_{a,pos,dl} = C_{a,dl}wl_a^2
$$
$$
M_{b,pos,dl} = C_{b,dl}wl_b^2
$$
Where, $w$ = uniform dead load per unit area
| Span Ratio, $m = l_a/l_b$ | Moment
Coefficient | Case 1
![Case 1]()
| Case 2
![Case 2]()
| Case 3
![Case 3]()
| Case 4
![Case 4]()
| Case 5
![Case 5]()
| Case 6
![Case 6]()
| Case 7
![Case 7]()
| Case 8
![Case 8]()
| Case 9
![Case 9]()
|
| ------------------------- | ----------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- |
| 1.00 | $C_{a,dl}$ | 0.036 | 0.018 | 0.018 | 0.027 | 0.027 | 0.033 | 0.027 | 0.020 | 0.023 |
| | $C_{b,dl}$ | 0.036 | 0.018 | 0.027 | 0.027 | 0.018 | 0.027 | 0.033 | 0.023 | 0.020 |
| 0.95 | $C_{a,dl}$ | 0.040 | 0.020 | 0.021 | 0.030 | 0.028 | 0.036 | 0.031 | 0.022 | 0.024 |
| | $C_{b,dl}$ | 0.033 | 0.016 | 0.025 | 0.024 | 0.015 | 0.024 | 0.031 | 0.021 | 0.017 |
| 0.90 | $C_{a,dl}$ | 0.045 | 0.022 | 0.025 | 0.033 | 0.029 | 0.039 | 0.035 | 0.025 | 0.026 |
| | $C_{b,dl}$ | 0.029 | 0.014 | 0.024 | 0.022 | 0.013 | 0.021 | 0.028 | 0.019 | 0.015 |
| 0.85 | $C_{a,dl}$ | 0.050 | 0.024 | 0.029 | 0.036 | 0.031 | 0.042 | 0.040 | 0.029 | 0.028 |
| | $C_{b,dl}$ | 0.026 | 0.012 | 0.022 | 0.019 | 0.011 | 0.017 | 0.025 | 0.017 | 0.013 |
| 0.80 | $C_{a,dl}$ | 0.056 | 0.026 | 0.034 | 0.039 | 0.032 | 0.045 | 0.045 | 0.032 | 0.029 |
| | $C_{b,dl}$ | 0.023 | 0.011 | 0.020 | 0.016 | 0.009 | 0.015 | 0.022 | 0.015 | 0.010 |
| 0.75 | $C_{a,dl}$ | 0.061 | 0.028 | 0.040 | 0.043 | 0.033 | 0.048 | 0.051 | 0.036 | 0.031 |
| | $C_{b,dl}$ | 0.019 | 0.009 | 0.018 | 0.013 | 0.007 | 0.012 | 0.020 | 0.013 | 0.007 |
| 0.70 | $C_{a,dl}$ | 0.068 | 0.030 | 0.046 | 0.046 | 0.035 | 0.051 | 0.058 | 0.040 | 0.033 |
| | $C_{b,dl}$ | 0.016 | 0.007 | 0.016 | 0.011 | 0.005 | 0.009 | 0.017 | 0.011 | 0.006 |
| 0.65 | $C_{a,dl}$ | 0.074 | 0.032 | 0.054 | 0.050 | 0.036 | 0.054 | 0.065 | 0.044 | 0.034 |
| | $C_{b,dl}$ | 0.013 | 0.006 | 0.014 | 0.009 | 0.004 | 0.007 | 0.014 | 0.009 | 0.005 |
| 0.60 | $C_{a,dl}$ | 0.081 | 0.034 | 0.062 | 0.053 | 0.037 | 0.056 | 0.073 | 0.048 | 0.036 |
| | $C_{b,dl}$ | 0.010 | 0.004 | 0.011 | 0.007 | 0.003 | 0.006 | 0.012 | 0.007 | 0.004 |
| 0.55 | $C_{a,dl}$ | 0.088 | 0.035 | 0.071 | 0.056 | 0.038 | 0.058 | 0.081 | 0.052 | 0.037 |
| | $C_{b,dl}$ | 0.008 | 0.003 | 0.009 | 0.005 | 0.002 | 0.004 | 0.009 | 0.005 | 0.003 |
| 0.50 | $C_{a,dl}$ | 0.095 | 0.037 | 0.080 | 0.059 | 0.039 | 0.061 | 0.089 | 0.056 | 0.038 |
| | $C_{b,dl}$ | 0.006 | 0.002 | 0.007 | 0.004 | 0.001 | 0.003 | 0.007 | 0.004 | 0.002 |
† A crosshatched edge indicates that the slab continues across, or is fixed at the support; an unmarked edge indicates a support at which torsional resistance is negligible.
Table 6.6.10: Coefficients for Live Load Positive Moments in Slabs†
$$
M_{a,pos,ll} = C_{a,ll}wl_a^2
$$
$$
M_{b,pos,ll} = C_{b,ll}wl_b^2
$$
Where, $w$ = uniform live load per unit area
| Span Ratio, $m = l_a/l_b$ | Moment
Coefficient | Case 1
![Case 1]()
| Case 2
![Case 2]()
| Case 3
![Case 3]()
| Case 4
![Case 4]()
| Case 5
![Case 5]()
| Case 6
![Case 6]()
| Case 7
![Case 7]()
| Case 8
![Case 8]()
| Case 9
![Case 9]()
|
| ------------------------- | ----------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- |
| 1.00 | $C_{a,ll}$ | 0.036 | 0.027 | 0.027 | 0.032 | 0.032 | 0.035 | 0.032 | 0.028 | 0.030 |
| | $C_{b,ll}$ | 0.036 | 0.027 | 0.032 | 0.032 | 0.027 | 0.032 | 0.035 | 0.030 | 0.028 |
| 0.95 | $C_{a,ll}$ | 0.040 | 0.030 | 0.031 | 0.035 | 0.034 | 0.038 | 0.036 | 0.031 | 0.032 |
| | $C_{b,ll}$ | 0.033 | 0.025 | 0.029 | 0.029 | 0.024 | 0.029 | 0.032 | 0.027 | 0.025 |
| 0.90 | $C_{a,ll}$ | 0.045 | 0.034 | 0.035 | 0.039 | 0.037 | 0.042 | 0.040 | 0.035 | 0.036 |
| | $C_{b,ll}$ | 0.029 | 0.022 | 0.027 | 0.026 | 0.021 | 0.025 | 0.029 | 0.024 | 0.022 |
| 0.85 | $C_{a,ll}$ | 0.050 | 0.037 | 0.040 | 0.043 | 0.041 | 0.046 | 0.045 | 0.040 | 0.039 |
| | $C_{b,ll}$ | 0.026 | 0.019 | 0.024 | 0.023 | 0.019 | 0.022 | 0.026 | 0.022 | 0.020 |
| 0.80 | $C_{a,ll}$ | 0.056 | 0.041 | 0.045 | 0.048 | 0.044 | 0.051 | 0.051 | 0.044 | 0.042 |
| | $C_{b,ll}$ | 0.023 | 0.017 | 0.022 | 0.020 | 0.016 | 0.019 | 0.023 | 0.019 | 0.017 |
| 0.75 | $C_{a,ll}$ | 0.061 | 0.045 | 0.051 | 0.052 | 0.047 | 0.055 | 0.056 | 0.049 | 0.046 |
| | $C_{b,ll}$ | 0.019 | 0.014 | 0.019 | 0.016 | 0.013 | 0.016 | 0.020 | 0.016 | 0.013 |
| 0.70 | $C_{a,ll}$ | 0.068 | 0.049 | 0.057 | 0.057 | 0.051 | 0.060 | 0.063 | 0.054 | 0.050 |
| | $C_{b,ll}$ | 0.016 | 0.012 | 0.016 | 0.014 | 0.011 | 0.013 | 0.017 | 0.014 | 0.011 |
| 0.65 | $C_{a,ll}$ | 0.074 | 0.053 | 0.064 | 0.062 | 0.055 | 0.064 | 0.070 | 0.059 | 0.054 |
| | $C_{b,ll}$ | 0.013 | 0.010 | 0.014 | 0.011 | 0.009 | 0.010 | 0.014 | 0.011 | 0.009 |
| 0.60 | $C_{a,ll}$ | 0.081 | 0.058 | 0.071 | 0.067 | 0.059 | 0.068 | 0.077 | 0.065 | 0.059 |
| | $C_{b,ll}$ | 0.010 | 0.007 | 0.011 | 0.009 | 0.007 | 0.008 | 0.011 | 0.009 | 0.007 |
| 0.55 | $C_{a,ll}$ | 0.088 | 0.062 | 0.080 | 0.072 | 0.063 | 0.073 | 0.085 | 0.070 | 00.063 |
| | $C_{b,ll}$ | 0.008 | 0.006 | 0.009 | 0.007 | 0.005 | 0.006 | 0.009 | 0.007 | 0.006 |
| 0.50 | $C_{a,ll}$ | 0.095 | 0.066 | 0.088 | 0.077 | 0.067 | 0.078 | 0.092 | 0.076 | 0.067 |
| | $C_{b,ll}$ | 0.006 | 0.004 | 0.007 | 0.005 | 0.004 | 0.005 | 0.007 | 0.005 | 0.004 |
† A crosshatched edge indicates that the slab continues across, or is fixed at the support; an unmarked edge indicates a support at which torsional resistance is negligible. (The 0.070/00.063 pair for span ratio 0.55, Case 8/9 of $C_{a,ll}$ is transcribed exactly as printed in the source gazette.)
Table 6.6.11: Ratio of Total Load $w$ in $l_a$ and $l_b$ Directions ($W_a$ and $W_b$) for Shear in Slab and Load on Supports†
| Span Ratio, $m = l_a/l_b$ | Load
Ratio | Case 1
![Case 1]()
| Case 2
![Case 2]()
| Case 3
![Case 3]()
| Case 4
![Case 4]()
| Case 5
![Case 5]()
| Case 6
![Case 6]()
| Case 7
![Case 7]()
| Case 8
![Case 8]()
| Case 9
![Case 9]()
|
| ------------------------- | --------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- | -------------------------------- |
| 1.00 | $w_a$ | 0.50 | 0.50 | 0.17 | 0.50 | 0.83 | 0.71 | 0.29 | 0.33 | 0.67 |
| | $w_b$ | 0.50 | 0.50 | 0.83 | 0.50 | 0.17 | 0.29 | 0.71 | 0.67 | 0.33 |
| 0.95 | $w_a$ | 0.55 | 0.55 | 0.20 | 0.55 | 0.86 | 0.75 | 0.33 | 0.38 | 0.71 |
| | $w_b$ | 0.45 | 0.45 | 0.80 | 0.45 | 0.14 | 0.25 | 0.67 | 0.62 | 0.29 |
| 0.90 | $w_a$ | 0.60 | 0.60 | 0.23 | 0.60 | 0.88 | 0.79 | 0.38 | 0.43 | 0.75 |
| | $w_b$ | 0.40 | 0.40 | 0.77 | 0.40 | 0.12 | 0.21 | 0.62 | 0.57 | 0.25 |
| 0.85 | $w_a$ | 0.66 | 0.66 | 0.28 | 0.66 | 0.90 | 0.83 | 0.43 | 0.49 | 0.79 |
| | $w_b$ | 0.34 | 0.34 | 0.72 | 0.34 | 0.10 | 0.17 | 0.57 | 0.51 | 0.21 |
| 0.80 | $w_a$ | 0.71 | 0.71 | 0.33 | 0.71 | 0.92 | 0.86 | 0.49 | 0.55 | 0.83 |
| | $w_b$ | 0.29 | 0.29 | 0.67 | 0.29 | 0.08 | 0.14 | 0.51 | 0.45 | 0.17 |
| 0.75 | $w_a$ | 0.76 | 0.76 | 0.39 | 0.76 | 0.94 | 0.88 | 0.56 | 0.61 | 0.86 |
| | $w_b$ | 0.24 | 0.24 | 0.61 | 0.24 | 0.06 | 0.12 | 0.44 | 0.39 | 0.14 |
| 0.70 | $w_a$ | 0.81 | 0.81 | 0.45 | 0.81 | 0.95 | 0.91 | 0.62 | 0.68 | 0.89 |
| | $w_b$ | 0.19 | 0.19 | 0.55 | 0.19 | 0.05 | 0.09 | 0.38 | 0.32 | 0.11 |
| 0.65 | $w_a$ | 0.85 | 0.85 | 0.53 | 0.85 | 0.96 | 0.93 | 0.69 | 0.74 | 0.92 |
| | $w_b$ | 0.15 | 0.15 | 0.47 | 0.15 | 0.04 | 0.07 | 0.31 | 0.26 | 0.08 |
| 0.60 | $w_a$ | 0.89 | 0.89 | 0.61 | 0.89 | 0.97 | 0.95 | 0.76 | 0.80 | 0.94 |
| | $w_b$ | 0.11 | 0.11 | 0.39 | 0.11 | 0.03 | 0.05 | 0.24 | 0.20 | 0.06 |
| 0.55 | $w_a$ | 0.92 | 0.92 | 0.69 | 0.92 | 0.98 | 0.96 | 0.81 | 0.85 | 0.95 |
| | $w_b$ | 0.08 | 0.08 | 0.31 | 0.08 | 0.02 | 0.04 | 0.19 | 0.15 | 0.05 |
| 0.50 | $w_a$ | 0.94 | 0.94 | 0.76 | 0.94 | 0.99 | 0.97 | 0.86 | 0.89 | 0.97 |
| | $w_b$ | 0.06 | 0.06 | 0.24 | 0.06 | 0.01 | 0.03 | 0.14 | 0.11 | 0.03 |
† A crosshatched edge indicates that the slab continues across, or is fixed at the support; an unmarked edge indicates a support at which torsional resistance is negligible.
#### 6.5.8.4 Shear on Supporting Beam
The shear requirements provided in Sec 6.5.6.8 shall be satisfied.
#### 6.5.8.5 Deflection
Thickness of slabs supported on walls or stiff beams on all sides shall satisfy the requirements of Sec 6.2.5.3.
#### 6.5.8.6 Reinforcement
##### 6.5.8.6.1
Area of reinforcement in each direction shall be determined from moments at critical sections but shall not be less than that required by Sec 8.1.11 Chapter 8.
##### 6.5.8.6.2
Spacing of reinforcement at critical sections shall not exceed two times the slab thickness, except for portions of slab area that may be of cellular or ribbed construction. In the slab over cellular spaces, reinforcement shall be provided as required by Sec 8.1.11 Chapter 8.
##### 6.5.8.6.3
Positive moment reinforcement perpendicular to a discontinuous edge shall extend to the edge of slab and have embedment, straight or hooked, at least 150 mm in spandrel beams, columns, or walls.
##### 6.5.8.6.4
Negative moment reinforcement perpendicular to a discontinuous edge shall be bent, hooked, or otherwise anchored, in spandrel beams, columns, or walls, and shall be developed at face of support according to provisions of Sec 8.2 Chapter 8.
##### 6.5.8.6.5 Corner reinforcement
Corner reinforcement shall be provided at exterior corners in both bottom and top of the slab, for a distance in each direction from the corner equal to one-fifth the longer span of the corner panel as per provisions of Sec 6.5.3.6.
### **6.5.9 Ribbed and Hollow Slabs**
#### 6.5.9.1 General
The provisions of this section shall apply to slabs constructed in one of the ways described below:
* (a) As a series of concrete ribs with topping cast on forms which may be removed after the concrete has set;
* (b) As a series of concrete ribs between precast blocks which remain part of the completed structure; the top of the ribs may be connected by a topping of concrete of the same strength as that used in the ribs;
* (c) Slabs with a continuous top and bottom face but containing voids of rectangular, oval or other shape.
#### 6.5.9.2 Analysis and design
Any method of analysis which satisfies equilibrium and compatibility requirements may be used for ribbed and hollow slabs. Approximate moments and shears in continuous one-way ribbed or hollow slabs may be obtained from Sec 6.1.4.3. For two-way slabs, the unified design approach specified in Sec 6.5 Flat Plates, Flat Slabs and Edge-supported Slabs, shall be used.
#### 6.5.9.3 Shear
##### 6.5.9.3.1
When burnt tile or concrete tile fillers of material having the same strength as the specified strength of concrete in the ribbed and hollow slabs are used permanently, it is permitted to include the vertical shells of fillers in contact with the ribs for shear and negative-moment strength computations, provided adequate bond between the two can be ensured.
#### 6.5.9.4 Deflection
The recommendations for deflection with respect to solid slabs may be applied to ribbed and hollow slab. Total depth of one-way ribbed and hollow slabs shall not be less than those required by Table 6.6.1 in Sec 6.2.5.2. For other slabs the provisions of Sec 6.2.5.3 shall apply.
#### 6.5.9.5 Size and Position of Ribs
In-situ-ribs shall be not less than 100 mm wide. They shall be spaced at centres not greater than 750 mm apart and their depth, excluding any topping, shall be not more than three and half times their width. Ribs shall be formed along each edge parallel to the span of one-way slabs.
#### 6.5.9.6 Reinforcement
The recommendations given in Sec 8.1.6 Chapter 8 regarding maximum distance between bars apply to areas of solid concrete in this form of construction. The curtailment, anchorage and cover to reinforcement shall be as specified below:
* (a) At least 50 percent of the total main reinforcement shall be carried through the bottom on to the bearing and anchored in accordance with Sec 8.2.8 Chapter 8.
* (b) Where a slab, which is continuous over supports, has been designed as simply supported, reinforcement shall be provided over the support to control cracking. This reinforcement shall have a cross-sectional area of not less than one quarter of that required in the middle of the adjoining spans and shall extend at least one-tenth of the clear span into adjoining spans.
In slabs with permanent blocks, the side cover to the reinforcement shall not be less than 10 mm. In all other cases, cover shall be provided according to Sec 8.1.7 Chapter 8.
##### 6.5.9.6.1
Adequate shear strength of slabs shall be provided in accordance with the requirements of Sec 6.4.10. For one-way ribbed and hollow slab construction, contribution of concrete to shear strength *Vc* is permitted to be 10 percent more than that specified in Sec 6.4.2. It is permitted to increase shear strength using shear reinforcement or by widening the ends of ribs.
## **6.6 Walls**
### **6.6.1 Scope**
#### 6.6.1.1
Provisions of Sec. 6.6 shall apply for design of walls subjected to axial load, with or without flexure.
#### 6.6.1.2
Cantilever retaining walls are designed according to flexural design provisions of Sec 6.3 with minimum horizontal reinforcement according to Sec 6.6.3.3.
### **6.6.2 General**
#### 6.6.2.1
Walls shall be designed for eccentric loads and any lateral or other loads to which they are subjected.
#### 6.6.2.2
Walls subject to axial loads shall be designed in accordance with Sections 6.6.2, 6.6.3, and either Sec 6.6.4, Sec 6.6.5, or Sec 6.6.8.
#### 6.6.2.3
Design for shear shall be in accordance with Sec 6.4.8.
#### 6.6.2.4
Unless otherwise demonstrated by an analysis, the horizontal length of wall considered as effective for each concentrated load shall not exceed the smaller of the center-to-center distance between loads, and the bearing width plus four times the wall thickness.
#### 6.6.2.5
Compression members built integrally with walls shall conform to Sec 6.3.8.2.
#### 6.6.2.6
Walls shall be anchored to intersecting elements, such as floors and roofs; or to columns pilasters, buttresses, of intersecting walls; and to footings.
#### 6.6.2.7
Quantity of reinforcement and limits of thickness required by Sections 6.6.3 and 6.6.5 shall be permitted to be waived where structural analysis shows adequate strength and stability.
#### 6.6.2.8
Transfer of force to footing at base of wall shall be in accordance with Sec 6.8.8.
### **6.6.3 Minimum reinforcement**
#### 6.6.3.1
Minimum vertical and horizontal reinforcement shall be in accordance with Sections 6.6.3.2 and 6.6.3.3 unless a greater amount is required for shear by Sections 6.4.8.8 and 6.4.8.9.
#### 6.6.3.2
Minimum ratio of vertical reinforcement area to gross concrete area, e, shall be:
* (a) 0.0012 for deformed bars not larger than 16 mm diameter with not less than 420 MPa; or
* (b) 0.0015 for other deformed bars; or
* (c) 0.0012 for welded wire reinforcement not larger than MW200 or MD200.
#### 6.6.3.3
Minimum ratio of horizontal reinforcement area to gross concrete area, , shall be:
* (a) 0.0020 for deformed bars not larger than 16 mm diameter with not less than 420 MPa; or
* (b) 0.0025 for other deformed bars; or
* (c) 0.0020 for welded wire reinforcement not larger than MW200 or MD200.
#### 6.6.3.4
Walls more than 250 mm thick, except basement walls, shall have reinforcement for each direction placed in two layers parallel with faces of wall in accordance with the following:
* (a) One layer consisting of not less than one-half and not more than twothirds of total reinforcement required for each direction shall be placed not less than 50 mm nor more than one-third the thickness of wall from the exterior surface;
* (b) The other layer, consisting of the balance of required reinforcement in that direction, shall be placed not less than 20 mm nor more than onethird the thickness of wall from the interior surface.
#### 6.6.3.5
Vertical and horizontal reinforcement shall not be spaced farther apart than three times the wall thickness, nor farther apart than 450 mm.
#### 6.6.3.6
Vertical reinforcement need not be enclosed by lateral ties if vertical reinforcement area is not greater than 0.01 times gross concrete area, or where vertical reinforcement is not required as compression reinforcement.
#### 6.6.3.7
In addition to the minimum reinforcement required by Sec 6.6.3.1, not less than two 16 mm diameter bars in walls having two layers of reinforcement in both directions and one 16 mm diameter bar in walls having a single layer of reinforcement in both directions shall be provided around window, door, and similar sized openings. Such bars shall be anchored to develop in tension at the corners of the openings.
### 6.6.4 Design of Walls as Compression Members
Except as provided in Sec 6.6.5, walls subject to axial load or combined flexure and axial load shall be designed as compression members in accordance with provisions of Sections 6.3.2, 6.3.3, 6.3.10, 6.3.11, 6.3.14, 6.6.2, and 6.6.3.
### 6.6.5 Empirical Method of Design
#### 6.6.5.1
Walls of solid rectangular cross section shall be permitted to be designed by the empirical provisions of Sec 6.6.5 if the resultant of all factored loads is located within the middle third of the overall thickness of the wall and all limits of Sections 6.6.2, 6.6.3, and 6.6.5 are satisfied.
#### 6.6.5.2
Design axial strength $\phi P_n$ of a wall satisfying limitations of Sec 6.6.5.1 shall be computed by Eq. 6.6.89 unless designed in accordance with 6.6.4.
$$
\phi P_n = 0.55\phi f_c'A_g\left[1-\left(\frac{Kl_c}{32h}\right)^2\right] \tag{6.6.89}
$$
Where, $\phi$ shall correspond to compression-controlled sections in accordance with Sec 6.2.3.2.2 and effective length factor $k$ shall be:
* (a) For walls braced top and bottom against lateral translation and
* Restrained against rotation at one or both ends (top, bottom, or 0.8
Unrestrained against rotation at both ends 1.0
(b) For walls not braced against lateral translation 2.0
#### 6.6.5.3 Minimum thickness of walls designed by empirical design method
##### 6.6.5.3.1
Thickness of bearing walls shall not be less than 1/25 the supported height or length, whichever is shorter, nor less than 100 mm.
##### 6.6.5.3.2
Thickness of exterior basement walls and foundation walls shall not be less than 190 mm.
### 6.6.6 Nonbearing Walls
#### 6.6.6.1
Thickness of nonbearing walls shall not be less than 100 mm, nor less than 1/30 the least distance between members that provide lateral support.
### 6.6.7 Walls as Grade Beams
#### 6.6.7.1
Walls designed as grade beams shall have top and bottom reinforcement as required for moment in accordance with provisions of Sections 6.3.2 to 6.3.7. Design for shear shall be in accordance with provisions of Sec. 6.4.
#### 6.6.7.2
Portions of grade beam walls exposed above grade shall also meet requirements of Sec 6.6.3.
### 6.6.8 Alternative Design of Slender Walls
#### 6.6.8.1
When flexural tension controls the out-of-plane design of a wall, the requirements of Sec 6.6.8 are considered to satisfy Sec 6.3.10.
#### 6.6.8.2
Walls designed by the provisions of Sec 6.6.8 shall satisfy Sections 6.6.8.2.1 to 6.6.8.2.6.
##### 6.6.8.2.1
The wall panel shall be designed as a simply supported, axially loaded member subjected to an out-of-plane uniform lateral load, with maximum moments and deflections occurring at midspan.
##### 6.6.8.2.2
The cross section shall be constant over the height of the panel.
##### 6.6.8.2.3
The wall shall be tension-controlled.
##### 6.6.8.2.4
Reinforcement shall provide a design Strength
$$
\phi M_n \geq M_{cr} \tag{6.6.90}
$$
Where, $M_{cr}$ shall be obtained using the modulus of rupture, $f_r$, given by Eq. 6.6.91.
##### 6.6.8.2.5
Concentrated gravity loads applied to the wall above the design flexural section shall be assumed to be distributed over a width:
* (a) Equal to the bearing width, plus a width on each side that increases at a slope of 2 vertical to 1 horizontal down to the design section; but
* (b) Not greater than the spacing of the concentrated loads; and
* (c) Not extending beyond the edges of the wall panel.
##### 6.6.8.2.6
Vertical stress $P_u/A_g$ at the midheight section shall not exceed $0.06f_c'$.
#### 6.6.8.3
Design moment strength $\phi M_n$ for combined flexure and axial loads at midheight shall be
$$
\phi M_n \geq M_u \tag{6.6.91}
$$
Where,
$$
M_u = M_{ua} + P_u\Delta_u \tag{6.6.92}
$$
$M_{ua}$ is the maximum factored moment at midheight of wall due to lateral and eccentric vertical loads, not including $P\Delta$ effects, and $\Delta_u$ is
$$
\Delta_u = \frac{5M_ul_c^2}{(0.75)48E_cI_{cr}} \tag{6.6.93}
$$
$M_u$ shall be obtained by iteration of deflections, or by Eq. 6.6.94.
$$
M_u = \frac{M_{ua}}{1 - \dfrac{5P_ul_c^2}{(0.75)48E_cI_{cr}}} \tag{6.6.94}
$$
Where,
$$
I_{cr} = \frac{E_s}{E_c}\left(A_s + \frac{P_u}{f_y}\frac{h}{2d}\right)(d-c)^2 + \frac{l_wc^3}{3} \tag{6.6.95}
$$
And, the value of $E_s/E_c$ shall not be taken less than 6.
#### 6.6.8.4
Maximum out-of-plane deflection, $\Delta_s$, due to service loads, including $P\Delta$ effects, shall not exceed $l_c/150$.
If $M_a$, maximum moment at midheight of wall due to service lateral and eccentric vertical loads, including $P\Delta$ effects, exceeds $(2/3)M_{cr}$, $\Delta_s$ shall be calculated by Eq. 6.6.96
$$
\Delta_s = (2/3)\Delta_{cr} + \frac{(M_a - (2/3)M_{cr})}{(M_n-(2/3)M_{cr})}(\Delta_n - (2/3)\Delta_{cr}) \tag{6.6.96}
$$
If $M_a$ does not exceed $(2/3)M_{cr}$, $\Delta_s$ shall be calculated by Eq. 6.6.97
$$
\Delta_s = \left(\frac{M_a}{M_{cr}}\right)\Delta_{cr} \tag{6.6.97}
$$
Where,
$$
\Delta_{cr} = \frac{5M_{cr}l_c^2}{48E_cI_g} \tag{6.6.98}
$$
$$
\Delta_n = \frac{5M_nl_c^2}{48E_cI_{cr}} \tag{6.6.99}
$$
$I_{cr}$ shall be calculated by Eq. 6.6.95, and $M_a$ shall be obtained by iteration of deflections.
## 6.7 Stairs
Stairs are the structural elements designed to connect different floors. The stairs shall be designed to meet the minimum load requirements. The flight arrangements, configuration and support conditions (Figure 6.6.24) shall govern the design procedure to follow.
### 6.7.1 Stairs Supported at Floor and Landing Level
#### 6.7.1.1 Effective span
The effective span of stairs without stringer beams shall be taken as the following horizontal distances:
* (a) Centre to centre distance of beams, where supported at top and bottom risers by beams spanning parallel with the risers,
* (b) Where supported at the edge of a landing slab, which spans parallel with the risers, (Figure 6.6.25a) a distance equal to the going of the stairs plus at each end either half the width of the landing or 1.0m whichever is smaller. The going shall be measured horizontally.
* (c) Where the landing spans in the same direction of the stairs (Figure 6.6.25b), the span shall be the distance centre to centre of the supporting beams or walls.
* (d) Where the landing slabs, running at right angle to the direction of the flight, supported by walls or beams on three sides (Figure 6.6.25c), the effective span shall be going of the stair measured horizontally. Both positive and negative moments along the direction of the flight shall be calculated as $l$q ⁄ , where w is the intensity of the total dead and live load per unit area 8 on a horizontal plane.
![Different configurations, flight arrangements and support conditions for stairs and landings]()
#### 6.7.1.2 Loading
Staircases shall be designed to support the design ultimate load according to the load combinations specified in Chapter 2, loads.
#### 6.7.1.3 Distribution of loading
6.7.1.3.1Where flights or landing are embedded at least 110 mm into walls and are designed to span in the direction of the flight, a 150 mm strip may be deducted from the loaded area and the effective breadth of the section may be increased by 75 mm for the purpose of design (Figure 6.6.26)
In the case of stairs with open wells, where spans cross at right angles, the load on areas common to any two such spans may be taken as one half in each direction as shown in Figure 6.6.27.
#### 6.7.1.4 Depth of section
The depth of the section shall be taken as the minimum thickness perpendicular to the soffit of the staircase.
#### 6.7.1.5 Design
##### 6.7.1.5.1 Strength, deflection and crack control
The recommendations given in Sections 6.1 and 6.2 for beams and one-way slabs shall apply, except for the span/depth ratio of staircases without stringer beam where the provision of Sec 6.7.1.5.2 below shall apply.
##### 6.7.1.5.2 Permissible span/effective depth ratio for staircase without stringer beams
In case of stair flight that occupies at least 60% of the span, the ratio calculated in accordance with Sec 6.2.5.2 shall be increased by 15%.
### 6.7.2 Special Types of Stairs
The provisions of special types of stairs like Free Standing (Landing unsupported), Sawtooth (Slabless) and Helicoidal are provided in Appendix M.
![Effective span determination for stairs supported at each end by landing slabs]()
![Effective breadth and loading distribution on stairs built in a wall]()
![Loading distribution on stairs with open wells where spans cross at right angles]()
## 6.8 Footings
### 6.8.1 Scope
#### 6.8.1.1
Provisions of Sec. 6.8 shall apply for design of isolated footings and, where applicable, to combined footings and mats.
#### 6.8.1.2
Additional requirements for design of combined footings and mats are given in Sec 6.8.10.
### 6.8.2 Loads and Reactions
#### 6.8.2.1
Footings shall be proportioned to resist the factored loads and induced reactions, in accordance with the appropriate design requirements of this Code and as provided in Sec. 6.8.
#### 6.8.2.2
Base area of footing or number and arrangement of piles shall be determined from unfactored forces and moments transmitted by footing to soil or piles and permissible soil pressure or permissible pile capacity determined using principles of soil mechanics.
#### 6.8.2.3
For footings on piles, computations for moments and shears shall be permitted to be based on the assumption that the reaction from any pile is concentrated at pile center.
### 6.8.3
Equivalent Square Shapes for Circular or Regular Polygon-Shaped Columns or Pedestals Supported By Footings
For location of critical sections for moment, shear, and development of reinforcement in footings, it shall be permitted to treat circular or regular polygon-shaped concrete columns or pedestals as square members with the same area.
### 6.8.4 Moment in Footings
#### 6.8.4.1
External moment on any section of a footing shall be determined by passing a vertical plane through the footing, and computing the moment of the forces acting over entire area of footing on one side of that vertical plane.
#### 6.8.4.2
Maximum factored moment, pk, for an isolated footing shall be computed as prescribed in Sec 6.8.4.1 at critical sections located as follows:
* (a) At face of column, pedestal, or wall, for footings supporting a concrete column, pedestal, or wall;
* (b) Halfway between middle and edge of wall, for footings supporting a masonry wall;
* (c) Halfway between face of column and edge of steel base plate, for footings supporting a column with steel base plate.
#### 6.8.4.3
In one-way footings and two-way square footings, reinforcement shall be distributed uniformly across entire width of footing.
#### 6.8.4.4
In two-way rectangular footings, reinforcement shall be distributed in accordance with Sections 6.8.4.4.1 and 6.8.4.4.2.
##### 6.8.4.4.1
Reinforcement in long direction shall be distributed uniformly across entire width of footing.
##### 6.8.4.4.2
For reinforcement in short direction, a portion of the total reinforcement, $\gamma_s A_s$, shall be distributed uniformly over a band width (centered on centerline of column or pedestal) equal to the length of short side of footing. Remainder of reinforcement required in short direction$(1 - \gamma_s) A_s$, shall be distributed uniformly outside center band width of footing.
Where, β is ratio of long to short sides of footing.
### 6.8.5 Shear in Footings
#### 6.8.5.1
Shear strength of footings supported on soil or rock shall be in accordance with Sec 6.4.10.
#### 6.8.5.2
Location of critical section for shear in accordance with Sec. 6.4 shall be measured from face of column, pedestal, or wall, for footings supporting a column, pedestal, or wall. For footings supporting a column or pedestal with steel base plates, the critical section shall be measured from location defined in Sec 6.8.4.2(c).
#### 6.8.5.3
Where the distance between axis of any pile to the axis of the column is more than two times the distance between the top of the pile cap and the top of the pile, the pile cap shall satisfy Sections 6.4.10 and 6.8.5.4. Other pile caps shall satisfy either Appendix I, or both Sections 6.4.10 and 6.8.5.4. If Appendix I is used, the effective concrete compression strength of the struts, !, shall be determined using Sec I.3.2.2(b).
#### 6.8.5.4
Computation of shear on any section through a footing supported on piles (Figure 6.6.28) shall be in accordance with Sections 6.8.5.4.1, 6.8.5.4.2, and 6.8.5.4.3.
*d* 6.8.5.4.1 Entire reaction from any pile with its center located *pile* or more 2
outside the section shall be considered as producing shear on that section.
*d* 6.8.5.4.2 Reaction from any pile with its center located *pile* or more inside 2
the section shall be considered as producing no shear on that section.
##### 6.8.5.4.3
For intermediate positions of pile center, the portion of the pile reaction to be considered as producing shear on the section shall be based on *d* straight-line interpolation between full value at *pile* outside the section and 2
![Modified critical perimeter for shear with overlapping critical perimeters in pile footings]()
### **6.8.6 Development of Reinforcement in Footings**
#### 6.8.6.1
Development of reinforcement in footings shall be in accordance with Sec. 8.2.
#### 6.8.6.2
Calculated tension or compression in reinforcement at each section shall be developed on each side of that section by embedment length, hook (tension only) or mechanical device, or a combination thereof.
#### 6.8.6.3
Critical sections for development of reinforcement shall be assumed at the same locations as defined in 6.8.4.2 for maximum factored moment, and at all other vertical planes where changes of section or reinforcement occur. See also 8.2.7.6.
### 6.8.7 Minimum Footing Depth
Depth of footing above bottom reinforcement shall not be less than 150 mm for footings on soil, nor less than 300 mm for footings on piles.
### **6.8.8 Force Transfer at Base of Column, Wall, or Reinforced Pedestal**
#### 6.8.8.1
Forces and moments at base of column, wall, or pedestal shall be transferred to supporting pedestal or footing by bearing on concrete and by reinforcement, dowels, and mechanical connectors.
##### 6.8.8.1.1
Bearing stress on concrete at contact surface between supported and supporting member shall not exceed concrete bearing strength for either surface as given by Sec 6.3.14.
##### 6.8.8.1.2
Reinforcement, dowels, or mechanical connectors between supported and supporting members shall be adequate to transfer:
* (a) All compressive force that exceeds concrete bearing strength of either member;
* (b) Any computed tensile force across interface.
In addition, reinforcement, dowels, or mechanical connectors shall satisfy Sec 6.8.8.2 or Sec 6.8.8.3.
##### 6.8.8.1.3
If calculated moments are transferred to supporting pedestal or footing, then reinforcement, dowels, or mechanical connectors shall be adequate to satisfy Sec 8.2.15.
##### 6.8.8.1.4
Lateral forces shall be transferred to supporting pedestal or footing in accordance with shear-friction provisions of Sec 6.4.5, or by other appropriate means.
#### 6.8.8.2
In cast-in-place construction, reinforcement required to satisfy Sec 6.8.8.1 shall be provided either by extending longitudinal bars into supporting pedestal or footing, or by dowels.
##### 6.8.8.2.1
For cast-in-place columns and pedestals, area of reinforcement across interface shall be not less than .0005 *Ag* , where *Ag* is the gross area of the supported member.
##### 6.8.8.2.2
For cast-in-place walls, area of reinforcement across interface shall be not less than minimum vertical reinforcement given in Sec 6.6.3.2.
##### 6.8.8.2.3
At footings, it shall be permitted to lap splice 43 mm diameter and 57 mm diameter longitudinal bars, in compression only, with dowels to provide reinforcement required to satisfy Sec 6.8.8.1. Dowels shall not be larger than 36 mm diameter bar and shall extend into supported member a distance not less than the larger of*l* *dc* ' of 43 mm diameter or 57 mm diameter bars and compression lap splice length of the dowels, whichever is greater, and into the footing a distance not less than*l* *dc* of the dowels.
##### 6.8.8.2.4
If a pinned or rocker connection is provided in cast-in-place construction, connection shall conform to the provisions of Sections 6.8.8.1 and 6.8.8.3.
#### 6.8.8.3
In precast construction, anchor bolts or suitable mechanical connectors shall be permitted for satisfying 6.8.8.1. Anchor bolts shall be designed in accordance with Appendix K.
##### 6.8.8.3.1
Connection between precast columns or pedestals and supporting members shall meet the requirements of Sec 6.10.5.1.3(a).
##### 6.8.8.3.2
Connection between precast walls and supporting members shall meet the requirements of Sec 6.10.5.1.3(b) and (c).
##### 6.8.8.3.3
Anchor bolts and mechanical connections shall be designed to reach their design strength before anchorage failure or failure of surrounding concrete. Anchor bolts shall be designed in accordance with Appendix K.
### 6.8.9 Stepped or Sloped Footings
#### 6.8.9.1
In sloped or stepped footings, angle of slope or depth and location of steps shall be such that design requirements are satisfied at every section. (See also Sec 8.2.7.6.)
#### 6.8.9.2
Sloped or stepped footings designed as a unit shall be constructed to ensure action as a unit.
### **6.8.10 Combined Footings and Mats**
#### 6.8.10.1
Footings supporting more than one column, pedestal, or wall (combined footings or mats) shall be proportioned to resist the factored loads and induced reactions, in accordance with appropriate design requirements of the Code.
#### 6.8.10.2
The direct design method of Sec. 6.5 shall not be used for design of combined footings and mats.
#### 6.8.10.3
Distribution of soil pressure under combined footings and mats shall be consistent with properties of the soil and the structure and with established principles of soil mechanics.
#### 6.8.10.4
Minimum reinforcing steel in mat foundations shall meet the requirements of Sec. 8.1.11.2 in each principal direction. Maximum spacing shall not exceed 450 mm.
## 6.9 Folded Plates and Shells
### 6.9.1 Scope and Definitions
#### 6.9.1.1
Provisions of Sec. 6.9 shall apply to thin shell and folded plate concrete structures, including ribs and edge members.
#### 6.9.1.2
All provisions of this Code not specifically excluded, and not in conflict with provisions of Sec. 6.9, shall apply to thin-shell structures.
#### 6.9.1.3 Thin shells
Three-dimensional spatial structures made up of one or more curved slabs or folded plates whose thicknesses are small compared to their other dimensions. Thin shells are characterized by their three-dimensional load-carrying behavior, which is determined by the geometry of their forms, by the manner in which they are supported, and by the nature of the applied load.
#### 6.9.1.4 Folded plates
A class of shell structure formed by joining flat, thin slabs along their edges to create a three-dimensional spatial structure.
#### 6.9.1.5 Ribbed shells
Spatial structures with material placed primarily along certain preferred rib lines, with the area between the ribs filled with thin slabs or left open.
#### 6.9.1.6 Auxiliary members
Ribs or edge beams that serve to strengthen, stiffen, or support the shell; usually, auxiliary members act jointly with the shell.
#### 6.9.1.7 Elastic analysis
An analysis of deformations and internal forces based on equilibrium, compatibility of strains, and assumed elastic behavior, and representing to a suitable approximation the three-dimensional action of the shell together with its auxiliary members.
#### 6.9.1.8 Inelastic analysis
An analysis of deformations and internal forces based on equilibrium, nonlinear stress-strain relations for concrete and reinforcement, consideration of cracking and time-dependent effects, and compatibility of strains. The analysis shall represent to a suitable approximation three-dimensional action of the shell together with its auxiliary members.
#### 6.9.1.9 Experimental analysis
An analysis procedure based on the measurement of deformations or strains, or both, of the structure or its model; experimental analysis is based on either elastic or inelastic behavior.
### 6.9.2 Analysis and Design
#### 6.9.2.1
Elastic behavior shall be an accepted basis for determining internal forces and displacements of thin shells. This behavior shall be permitted to be established by computations based on an analysis of the uncracked concrete structure in which the material is assumed linearly elastic, homogeneous, and isotropic. Poisson\phis ratio of concrete shall be permitted to be taken equal to zero.
#### 6.9.2.2
Inelastic analyses shall be permitted to be used where it can be shown that such methods provide a safe basis for design.
#### 6.9.2.3
Equilibrium checks of internal resistances and external loads shall be made to ensure consistency of results.
#### 6.9.2.4
Experimental or numerical analysis procedures shall be permitted where it can be shown that such procedures provide a safe basis for design.
#### 6.9.2.5
Approximate methods of analysis shall be permitted where it can be shown that such methods provide a safe basis for design.
#### 6.9.2.6
The thickness of a shell and its reinforcement shall be proportioned for the required strength and serviceability, using either the strength design method of Sec 6.1.2.1 or the design method of Sec 6.1.2.2.
#### 6.9.2.7
Shell instability shall be investigated and shown by design to be precluded.
#### 6.9.2.8
Auxiliary members shall be designed according to the applicable provisions of the Code. It shall be permitted to assume that a portion of the shell equal to the flange width, as specified in Sec 6.1.13, acts with the auxiliary member. In such portions of the shell, the reinforcement perpendicular to the auxiliary member shall be at least equal to that required for the flange of a T- beam by Sec 6.1.13.5.
#### 6.9.2.9
Strength design of shell slabs for membrane and bending forces shall be based on the distribution of stresses and strains as determined from either an elastic or an inelastic analysis.
#### 6.9.2.10
In a region where membrane cracking is predicted, the nominal compressive strength parallel to the cracks shall be taken as 0.4r .
### 6.9.3 Design Strength of Materials
#### 6.9.3.1
Specified compressive strength of concrete r at 28 days shall not be less than 21 MPa.
#### 6.9.3.2
Specified yield strength of reinforcement shall not exceed 420 MPa.
### 6.9.4 Shell Reinforcement
#### 6.9.4.1
Shell reinforcement shall be provided to resist tensile stresses from internal membrane forces, to resist tension from bending and twisting moments, to limit shrinkage and temperature crack width and spacing, and as reinforcement at shell boundaries, load attachments, and shell openings.
#### 6.9.4.2
Tensile reinforcement shall be provided in two or more directions and shall be proportioned such that its resistance in any direction equals or exceeds the component of internal forces in that direction. Alternatively, reinforcement for the membrane forces in the slab shall be calculated as the reinforcement required to resist axial tensile forces plus the tensile force due to shear-friction required to transfer shear across any cross section of the membrane. The assumed coefficient of friction, ¦, shall not exceed that specified in Sec 6.4.5.4.3.
#### 6.9.4.3
The area of shell reinforcement at any section as measured in two orthogonal directions shall not be less than the slab shrinkage or temperature reinforcement required by Sec 8.1.11.
#### 6.9.4.4
Reinforcement for shear and bending moments about axes in the plane of the shell slab shall be calculated in accordance with Sections 6.3, 6.4 and 6.5.
#### 6.9.4.5
The area of shell tension reinforcement shall be limited so that the reinforcement will yield before either crushing of concrete in compression or shell buckling can take place.
#### 6.9.4.6
In regions of high tension, membrane reinforcement shall, if practical, be placed in the general directions of the principal tensile membrane forces. Where this is not practical, it shall be permitted to place membrane reinforcement in two or more component directions.
#### 6.9.4.7
If the direction of reinforcement varies more than 10o from the direction of principal tensile membrane force, the amount of reinforcement shall be reviewed in relation to cracking at service loads.
#### 6.9.4.8
Where the magnitude of the principal tensile membrane stress within the shell varies greatly over the area of the shell surface, reinforcement resisting the total tension shall be permitted to be concentrated in the regions of largest tensile stress where it can be shown that this provides a safe basis for design. However, the ratio of shell reinforcement in any portion of the tensile zone shall be not less than 0.0035 based on the overall thickness of the shell.
#### 6.9.4.9
Reinforcement required to resist shell bending moments shall be proportioned with due regard to the simultaneous action of membrane axial forces at the same location. Where shell reinforcement is required in only one face to resist bending moments, equal amounts shall be placed near both surfaces of the shell even though a reversal of bending moments is not indicated by the analysis.
#### 6.9.4.10
Shell reinforcement in any direction shall not be spaced farther apart than 450 mm nor farther apart than five times the shell thickness. Where the principal membrane tensile stress on the gross concrete area due to factored loads exceeds $0.33\phi\lambda\sqrt{f_c'}$, reinforcement shall not be spaced farther apart than three times the shell thickness.
#### 6.9.4.11
Shell reinforcement at the junction of the shell and supporting members or edge members shall be anchored in or extended through such members in accordance with the requirements of Sec. 8.2, except that the minimum development length shall be 1.2$l$w but not less than 450 mm.
#### 6.9.4.12
Splice lengths of shell reinforcement shall be governed by the provisions of Sec. 8.2, except that the minimum splice length of tension bars shall be 1.2 times the value required by Sec. 8.2 but not less than 450 mm. The number of splices in principal tensile reinforcement shall be kept to a practical minimum. Where splices are necessary they shall be staggered at least $l$w with not more than one-third of the reinforcement spliced at any section.
### 6.9.5 Construction
#### 6.9.5.1
When removal of formwork is based on a specific modulus of elasticity of concrete because of stability or deflection considerations, the value of the modulus of elasticity, , used shall be determined from flexural tests of fieldcured beam specimens. The number of test specimens, the dimensions of test beam specimens, and test procedures shall be specified by the Engineer.
#### 6.9.5.2
Contract documents shall specify the tolerances for the shape of the shell. If construction results in deviations from the shape greater than the specified tolerances, an analysis of the effect of the deviations shall be made and any required remedial actions shall be taken to ensure safe behavior.
## 6.10 Precast Concrete
### 6.10.1 Scope
#### 6.10.1.1
All provisions of this Code, not specifically excluded and not in conflict with the provisions of Sec 6.10, shall apply to structures incorporating precast concrete structural members.
### 6.10.2 General
#### 6.10.2.1
Design of precast members and connections shall include loading and restraint conditions from initial fabrication to end use in the structure, including form removal, storage, transportation, and erection.
#### 6.10.2.2
When precast members are incorporated into a structural system, the forces and deformations occurring in and adjacent to connections shall be included in the design.
#### 6.10.2.3
Tolerances for both precast members and interfacing members shall be specified. Design of precast members and connections shall include the effects of these tolerances.
#### 6.10.2.4
In addition to the requirements for drawings and specifications in Sec 1.9.3 of Chapter 1, the following (a) and (b) shall be included in either the contract documents or shop drawings:
* (a) Details of reinforcement, inserts and lifting devices required to resist temporary loads from handling, storage, transportation, and erection;
* (b) Required concrete strength at stated ages or stages of construction.
### 6.10.3 Distribution of Forces in Members
#### 6.10.3.1
Distribution of forces that are perpendicular to the plane of members shall be established by analysis or by test.
#### 6.10.3.2
Where the system behavior requires in-plane forces to be transferred between the members of a precast floor or wall system, Sections 6.10.3.2.1 and 6.10.3.2.2 shall apply.
##### 6.10.3.2.1
In-plane force paths shall be continuous through both connections and members.
##### 6.10.3.2.2
Where tension forces occur, a continuous path of steel or steel reinforcement shall be provided.
### 6.10.4 Member Design
#### 6.10.4.1
In one-way precast floor and roof slabs and in one-way precast, prestressed wall panels, all not wider than 3.7 m, and where members are not mechanically connected to cause restraint in the transverse direction, the shrinkage and temperature reinforcement requirements of Sec. 8.1.11 in the direction normal to the flexural reinforcement shall be permitted to be waived. This waiver shall not apply to members that require reinforcement to resist transverse flexural stresses.
#### 6.10.4.2
For precast, non prestressed walls the reinforcement shall be designed in accordance with the provisions of Sec 6.3 or Sec 6.6, except that the area of horizontal and vertical reinforcement each shall be not less than 0.001-U, where -U is the gross cross-sectional area of the wall panel. Spacing of reinforcement shall not exceed 5 times the wall thickness nor 750 mm for interior walls nor 450 mm for exterior walls.
### 6.10.5 Structural Integrity
#### 6.10.5.1
Except where the provisions of Sec 6.10.5.2 govern, the minimum provisions of Sec 6.10.5.1.1 to 6.10.5.1.4 for structural integrity shall apply to all precast concrete structures.
##### 6.10.5.1.1
Longitudinal and transverse ties required by Sec 8.1.12.3 shall connect members to a lateral load-resisting system.
##### 6.10.5.1.2
Where precast elements form floor or roof diaphragms, the connections between diaphragm and those members being laterally supported shall have a nominal tensile strength capable of resisting not less than 4.4 kN per linear m.
##### 6.10.5.1.3
Vertical tension tie requirements of Sec 8.1.12.3 shall apply to all vertical structural members, except cladding, and shall be achieved by providing connections at horizontal joints in accordance with (a) through (c):
* (a) Precast columns shall have a nominal strength in tension not less than 1.4-U, in N. For columns with a larger cross section than required by consideration of loading, a reduced effective area -U(in mm2 ), based on cross-section required but not less than one-half the total area, shall be permitted;
* (b) Precast wall panels shall have a minimum of two ties per panel, with a nominal tensile strength not less than 44 kN per tie;
* (c) When design forces result in no tension at the base, the ties required by Sec 6.10.5.1.3(b) shall be permitted to be anchored into an appropriately reinforced concrete floor slab-on-ground.
##### 6.10.5.1.4
Connection details that rely solely on friction caused by gravity loads shall not be used.
#### 6.10.5.2
For precast concrete bearing wall structures three or more stories in height, the minimum provisions of Sections 6.10.5.2.1 to 6.10.5.2.5 shall apply (Figure 6.6.29).
##### 6.10.5.2.1
Longitudinal and transverse ties shall be provided in floor and roof systems to provide a nominal strength of 22 kN per meter of width or length. Ties shall be provided over interior wall supports and between members and exterior walls. Ties shall be positioned in or within 600 mm of the plane of floor or roof system.
##### 6.10.5.2.2
Longitudinal ties parallel to floor or roof slab spans shall be spaced not more than 3 m on centers. Provisions shall be made to transfer forces around openings.
##### 6.10.5.2.3
Transverse ties perpendicular to floor or roof slab spans shall be spaced not greater than the bearing wall spacing.
##### 6.10.5.2.4
Ties around the perimeter of each floor and roof, within 1.2 m of the edge, shall provide a nominal strength in tension not less than 71 kN.
##### 6.10.5.2.5
Vertical tension ties shall be provided in all walls and shall be continuous over the height of the building. They shall provide a nominal tensile strength not less than 44 kN per horizontal meter of wall. Not less than two ties shall be provided for each precast panel.
![Typical arrangement of longitudinal, transverse, and vertical tensile ties in large panel precast structures]()
### 6.10.6 Connection and Bearing Design
#### 6.10.6.1
Forces shall be permitted to be transferred between members by grouted joints, shear keys, mechanical connectors, reinforcing steel connections, reinforced topping, or a combination of these means.
##### 6.10.6.1.1
The adequacy of connections to transfer forces between members shall be determined by analysis or by test. Where shear is the primary result of imposed loading, it shall be permitted to use the provisions of Sec 6.4.5 as applicable.
##### 6.10.6.1.2
When designing a connection using materials with different structural properties, their relative stiffnesses, strengths, and ductilities shall be considered.
#### 6.10.6.2
Bearing for precast floor and roof members on simple supports shall satisfy Sections 6.10.6.2.1 and 6.10.6.2.2.
##### 6.10.6.2.1
The allowable bearing stress at the contact surface between supported and supporting members and between any intermediate bearing elements shall not exceed the bearing strength for either surface or the bearing element, or both. Concrete bearing strength shall be as given in Sec 6.3.14.
##### 6.10.6.2.2
Unless shown by test or analysis that performance will not be impaired, (a) and (b) shall be met (Figure 6.6.30):
* (a) Each member and its supporting system shall have design dimensions selected so that, after consideration of tolerances, the distance from the edge of the support to the end of the precast member in the direction of the span is at least $l_n$/180, but not less than:
For solid or hollow-core slabs 50 mm For beams or stemmed members 75 mm
* (b) Bearing pads at unarmored edges shall be set back a minimum of 13 mm from the face of the support, or at least the chamfer dimension at chamfered edges.
##### 6.10.6.2.3
The requirements of Sec 8.2.8.1 shall not apply to the positive bending moment reinforcement for statically determinate precast members, but at least one-third of such reinforcement shall extend to the center of the bearing length, taking into account permitted tolerances in Sections 8.1.5.2c and 6.10.2.3.
![Bearing length, setback, and tolerance dimensions for precast members on simple supports]()
### 6.10.7 Items Embedded after Concrete Placement
#### 6.10.7.1
When approved by the designer, embedded items (such as dowels or inserts) that either protrude from the concrete or remain exposed for inspection shall be permitted to be embedded while the concrete is in a plastic state provided that Sections 6.10.7.1.1, 6.10.7.1.2, and 6.10.7.1.3 are met.
##### 6.10.7.1.1
Embedded items are not required to be hooked or tied to reinforcement within the concrete.
##### 6.10.7.1.2
Embedded items are maintained in the correct position while the concrete remains plastic.
##### 6.10.7.1.3
The concrete is properly consolidated around the embedded item.
### 6.10.8 Marking and Identification
#### 6.10.8.1
Each precast member shall be marked to indicate its location and orientation in the structure and date of manufacture.
#### 6.10.8.2
Identification marks shall correspond to placing drawings.
### 6.10.9 Handling
#### 6.10.9.1
Member design shall consider forces and distortions during curing, stripping, storage, transportation, and erection so that precast members are not overstressed or otherwise damaged.
#### 6.10.9.2
During erection, precast members and structures shall be adequately supported and braced to ensure proper alignment and structural integrity until permanent connections are completed.
### 6.10.10 Evaluation of Strength of Precast Construction
#### 6.10.10.1
A precast element to be made composite with cast-in-place concrete shall be permitted to be tested in flexure as a precast element alone in accordance with Sections 6.10.10.1.1 and 6.10.10.1.2.
6.10.10.1.1Test loads shall be applied only when calculations indicate the isolated precast element will not be critical in compression or buckling.
6.10.10.1.2The test load shall be that load which, when applied to the precast member alone, induces the same total force in the tension reinforcement as would be induced by loading the composite member with the test load required by Sec 6.11.3.2.
#### 6.10.10.2
The provisions of Sec 6.11.5 shall be the basis for acceptance or rejection of the precast element.
## 6.11 Evaluation of Strength of Existing Structures
### 6.11.1 Strength Evaluation - General
#### 6.11.1.1
If there is doubt that a part or all of a structure meets the safety requirements of this Code, a strength evaluation shall be carried out as required by the Engineer.
#### 6.11.1.2
If the effect of the strength deficiency is well understood and if it is feasible to measure the dimensions and material properties required for analysis, analytical evaluations of strength based on those measurements shall suffice. Required data shall be determined in accordance with Sec 6.11.2.
#### 6.11.1.3
If the effect of the strength deficiency is not well understood or if it is not feasible to establish the required dimensions and material properties by measurement, a load test shall be required if the structure is to remain in service.
#### 6.11.1.4
If the doubt about safety of a part or all of a structure involves deterioration, and if the observed response during the load test satisfies the acceptance criteria, the structure or part of the structure shall be permitted to remain in service for a specified time period. If deemed necessary by the Engineer, periodic reevaluations shall be conducted.
### 6.11.2 Determination of Material Properties and Required Dimensions
#### 6.11.2.1
Dimensions of the structural elements shall be established at critical sections.
#### 6.11.2.2
Locations and sizes of the reinforcing bars, welded wire reinforcement, or tendons shall be determined by measurement. It shall be permitted to base reinforcement locations on available drawings if spot checks are made confirming the information on the drawings.
#### 6.11.2.3
If required, concrete strength shall be based on results of cylinder tests from the original construction or tests of cores removed from the part of the structure where the strength is in question. For strength evaluation of an existing structure, cylinder or core test data shall be used to estimate an equivalent r . The method for obtaining and testing cores shall be in accordance with ASTM C42M.
#### 6.11.2.4
If required, reinforcement or prestressing steel strength shall be based on tensile tests of representative samples of the material in the structure in question.
#### 6.11.2.5
If the required dimensions and material properties are determined through measurements and testing, and if calculations can be made in accordance with Sec 6.11.1.2, it shall be permitted to increase φ from those specified in 6.2.3, but $\phi$ shall not be more than:
| Tension-controlled sections, as defined in 6.3.3.4
Compression-controlled sections, as defined in Sec 6.3.3.3: | 1.0 |
| ------------------------------------------------------------------------------------------------------------------- | --- |
| Members with spiral reinforcement conforming to Sec
6.3.9.3 | 0.9 |
| Other reinforced members | 0.8 |
| Shear and/or torsion | 0.8 |
| Bearing on concrete | 0.8 |
### 6.11.3 Load Test Procedure
#### 6.11.3.1 Load arrangement
The number and arrangement of spans or panels loaded shall be selected to maximize the deflection and stresses in the critical regions of the structural elements of which strength is in doubt. More than one test load arrangement shall be used if a single arrangement will not simultaneously result in maximum values of the effects (such as deflection, rotation, or stress) necessary to demonstrate the adequacy of the structure.
#### 6.11.3.2 Load intensity
The total test load (including dead load already in place) shall not be less than the larger of (a), (b), and (c):
* (a) 1.15 D + 1.5$L$ + 0.4($L_r$)
* (b) 1.15 D + 0.9$L$ + 1.5($L_r$)
* (c) $1.3D$
The load factor on the live load $L$ in (b) shall be permitted to be reduced to 0.45 except for garages, areas occupied as places of public assembly, and all areas where, $L$ is greater than 4.8 kN/m2 . It shall be permitted to reduce $L$ in accordance with the provisions of this Code.
#### 6.11.3.3
A load test shall not be made until that portion of the structure to be subjected to load is at least 56 days old. If the owner of the structure, the contractor, and all involved parties agree, it shall be permitted to make the test at an earlier age.
### 6.11.4 Loading Criteria
#### 6.11.4.1
The initial value for all applicable response measurements (such as deflection, rotation, strain, slip, crack widths) shall be obtained not more than 1 hour before application of the first load increment. Measurements shall be made at locations where maximum response is expected. Additional measurements shall be made if required.
#### 6.11.4.2
Test load shall be applied in not less than four approximately equal increments.
#### 6.11.4.3
Uniform test load shall be applied in a manner to ensure uniform distribution of the load transmitted to the structure or portion of the structure being tested. Arching of the applied load shall be avoided.
#### 6.11.4.4
A set of response measurements shall be made after each load increment is applied and after the total load has been applied on the structure for at least 24 hours.
#### 6.11.4.5
Total test load shall be removed immediately after all response measurements defined in Sec 6.11.4.4 are made.
#### 6.11.4.6
A set of final response measurements shall be made 24 hours after the test load is removed.
### 6.11.5 Acceptance Criteria
#### 6.11.5.1
The portion of the structure tested shall show no evidence of failure. Spalling and crushing of compressed concrete shall be considered an indication of failure.
#### 6.11.5.2
Measured deflections shall satisfy either Eq. (6.6.101) or (6.6.102):
If the measured maximum and residual deflections, $\Delta_s$ and $\Delta_s$, do not satisfy Eq. (6.6.101) or (6.6.102), it shall be permitted to repeat the load test.
The repeat test shall be conducted not earlier than 72 hours after removal of the first test load. The portion of the structure tested in the repeat test shall be considered acceptable if deflection recovery $\Delta_s$ satisfies the condition:
Where, $\Delta_s$q is the maximum deflection measured during the second test relative to the position of the structure at the beginning of the second test.
#### 6.11.5.3
Structural members tested shall not have cracks indicating the imminence of shear failure.
#### 6.11.5.4
In regions of structural members without transverse reinforcement, appearance of structural cracks inclined to the longitudinal axis and having a horizontal projection longer than the depth of the member at midpoint of the crack shall be evaluated.
#### 6.11.5.5
In regions of anchorage and lap splices, the appearance along the line of reinforcement of a series of short inclined cracks or horizontal cracks shall be evaluated.
### 6.11.6 Provision for Lower Load Rating
If the structure under investigation does not satisfy conditions or criteria of Sec 6.11.1.2, Sec 6.11.5.2, or Sec 6.11.5.3, the structure shall be permitted for use at a lower load rating based on the results of the load test or analysis, if approved by the Engineer.
### 6.11.7 Safety
#### 6.11.7.1
Load tests shall be conducted in such a way as to provide for safety of life and structure during test.
#### 6.11.7.2
Safety measures shall not interfere with load test procedures or affect results.
## 6.12 Composite Concrete Flexural Members
### 6.12.1 Scope
#### 6.12.1.1
Provisions of Sec 6.12 shall apply for design of composite concrete flexural members defined as precast concrete, cast-in-place concrete elements, or both, constructed in separate placements but so interconnected that all elements respond to loads as a unit.
#### 6.12.1.2
All provisions of the Code shall apply to composite concrete flexural members, except as specifically modified in Sec 6.12.
### 6.12.2 General
#### 6.12.2.1
The use of an entire composite member or portions thereof for resisting shear and moment shall be permitted.
#### 6.12.2.2
Individual elements shall be investigated for all critical stages of loading.
#### 6.12.2.3
If the specified strength, unit weight, or other properties of the various elements are different, properties of the individual elements or the most critical values shall be used in design.
#### 6.12.2.4
In strength computations of composite members, no distinction shall be made between shored and unshored members.
#### 6.12.2.5
All elements shall be designed to support all loads introduced prior to full development of design strength of composite members.
#### 6.12.2.6
Reinforcement shall be provided as required to minimize cracking and to prevent separation of individual elements of composite members.
#### 6.12.2.7
Composite members shall meet requirements for control of deflections in accordance with Sec 6.2.5.4.
### 6.12.3 Shoring
When used, shoring shall not be removed until supported elements have developed design properties required to support all loads and limit deflections and cracking at time of shoring removal.
### 6.12.4 Vertical Shear Strength
#### 6.12.4.1
Where an entire composite member is assumed to resist vertical shear, design shall be in accordance with requirements of Sec 6.4 as for a monolithically cast member of the same cross-sectional shape.
#### 6.12.4.2
Shear reinforcement shall be fully anchored into interconnected elements in accordance with Sec 8.2.10.
#### 6.12.4.3
Extended and anchored shear reinforcement shall be permitted to be included as ties for horizontal shear.
### 6.12.5 Horizontal Shear Strength
#### 6.12.5.1
In a composite member, full transfer of horizontal shear forces shall be ensured at contact surfaces of interconnected elements.
#### 6.12.5.2
For the provisions of Sec 6.12.5, 0 shall be taken as the distance from extreme compression fiber for entire composite section to centroid of longitudinal tension reinforcement, if any.
#### 6.12.5.3
Unless calculated in accordance with Sec 6.12.5.4, design of cross sections subject to horizontal shear shall be based on
$$
V_u \leq \phi V_{nh} \tag{6.6.104}
$$
Where, $V_{nh}$ is nominal horizontal shear strength in accordance with Sections 6.12.5.3.1 to 6.12.5.3.4.
##### 6.12.5.3.1
Where contact surfaces are clean, free of laitance, and intentionally roughened, *Vnh* shall not be taken greater than 0.55 *bνd* .
##### 6.12.5.3.2
Where minimum ties are provided in accordance with Sec 6.12.6, and contact surfaces are clean and free of laitance, but not intentionally roughened, *Vnh* shall not be taken greater than 0.55 *bνd* .
##### 6.12.5.3.3
Where ties are provided in accordance with Sec 6.12.6, and contact surfaces are clean, free of laitance, and intentionally roughened to a full amplitude of approximately 6 mm, *Vnh* shall be taken equal to, (1.8 + 0.6 *ρv fv* ) *bvd* , but not greater than 3.5 *bvd* . Values for in Sec 6.4.5.4.3 shall apply and*ρ* *v*is A *v /(bvs).*
##### 6.12.5.3.4
Where *Vu* at section considered exceeds $\phi$(3.5 *bvd)* , design for horizontal shear shall be in accordance with Sec 6.4.5.4.
#### 6.12.5.4
As an alternative to Sec 6.12.5.3, horizontal shear shall be permitted to be determined by computing the actual change in compressive or tensile force in any segment, and provisions shall be made to transfer that force as horizontal shear to the supporting element. The factored horizontal shear force $V_u$ shall not exceed horizontal shear strength $\phi V_{nh}$ as given in Sections 6.12.5.3.1 to 6.12.5.3.4, where area of contact surface shall be substituted for $b_vd$.
##### 6.12.5.4.1
Where ties provided to resist horizontal shear are designed to satisfy Sec 6.12.5.4, the tie area to tie spacing ratio along the member shall approximately reflect the distribution of shear forces in the member.
#### 6.12.5.5
Where tension exists across any contact surface between interconnected elements, shear transfer by contact shall be permitted only when minimum ties are provided in accordance with Sec 6.12.6.
### **6.12.6** Ties for Horizontal Shear
#### 6.12.6.1
Where ties are provided to transfer horizontal shear, tie area shall not be less than that required by Sec 6.4.3.5.3, and tie spacing shall not exceed four times the least dimension of supported element, nor exceed 600 mm.
#### 6.12.6.2
Ties for horizontal shear shall consist of single bars or wire, multiple leg stirrups, or vertical legs of welded wire reinforcement.
#### 6.12.6.3
All ties shall be fully anchored into interconnected elements in accordance with Sec 8.2.10.
## 6.13 List of Related Appendices
Appendix I Strut-and-Tie Models
Appendix J Working Stress Design Method for Reinforced Concrete Structures
Appendix K Anchoring to Concrete
Appendix L Information on Steel Reinforcement
Appendix M Special Types of Stairs
# Chapter 7: Masonry Structures
Source: https://docs.sayed.app/bnbc/part-6-structural-design/chapter-7-masonry-structures
## 7.1 Introduction
### 7.1.1 Scope
This Chapter of the Code covers the design, construction and quality control of masonry structures.
### 7.1.2 Definitions
For the purpose of this Chapter, the following definitions shall be applicable.
| ACTUAL
DIMENSIONS | The measured dimensions of a designated item; such as a
designated masonry unit or wall used in the structures.
The actual dimension shall not vary from the specified
dimension by more than the amount allowed in the
appropriate standard mentioned in Sec 2.2.4 Chapter 2
Part 5. |
| ---------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| BED BLOCK | A block bedded on a wall, column or pier to disperse a
concentrated load on a masonry element. |
| BED JOINT | A horizontal mortar joint upon which masonry units are
placed. |
| BOND | Arrangement of masonry units in successive courses to tie
the
masonry
together
both
longitudinally
and
transversely; the arrangement is usually worked out to
ensure that no vertical joint of one course is exactly over
the one in the next course above or below it and there is
maximum possible amount of lap. |
| BOND BEAM | A horizontal grouted element within masonry in which
reinforcement is embedded. |
| BUTTRESS | A pier of masonry built as an integral part of wall and
projecting from either or both surfaces, decreasing in
cross-sectional area from base to top and conforming to
the requirement of Sec 4.3.3(c) (ii). |
| CAVITY WALL | A wall comprising two limbs each built-up as single or
multi-wythe units and separated by a 50-115 mm wide
cavity. The limbs are tied together by metal ties or
bonding units for structural integrity. |
| CELL | A void space having a gross cross-sectional area greater
than 1000 mm2. |
| COLLAR JOINT | The vertical, longitudinal, mortar or grouted joints. |
| COLUMN | An isolated vertical load bearing member the width of
which does not exceed three times the thickness. |
| CROSS JOINT | A vertical joint normal to the face of the wall. |
| CROSS-
SECTIONAL AREA
OF MASONRY
UNIT | Net cross-sectional area of masonry unit is the gross
cross-sectional area minus the area of cellular space. |
| CURTAIN WALL | A non-load bearing self-supporting wall subject to
transverse lateral loads, and laterally supported by
vertical or horizontal structural member where necessary. |
| FACED WALL | A wall in which facing and backing of two different
materials are bonded together to ensure common action
under load. |
| GROUT | A mixture of cementitious materials and aggregate to
which water is added such that the mixture will flow
without segregation of the constituents. |
| GROUTED
HOLLOW-UNIT
MASONRY | That form of grouted masonry construction in which
certain designated cells of hollow units are continuously
filled with grout. |
| GROUTED
MULTI-WYTHE
MASONRY | That form of grouted masonry construction in which the
space between the wythes is solidly or periodically filled
with grout. |
| HOLLOW UNIT | A masonry unit of which net cross-sectional area in any
plane parallel to the bearing surface is less than 75
percent of its gross cross-sectional area measured in the
same plane. |
| JAMB | Side of an opening in wall. |
| HEAD JOINT | The mortar joint having a vertical transverse plane. |
| LATERAL
SUPPORT | A support which enables a masonry element to resist
lateral load and/or restrains lateral deflection of a
masonry element at the point of support. |
| LIMB | Inner or outer portion of a cavity wall. |
| LOAD BEARING
WALL | A wall designed to carry an imposed vertical load in
addition to its own weight, together with any lateral load. |
| MASONRY | An assemblage of masonry units properly bonded
together with mortar. |
| MASONRY UNIT | Individual units, such as brick, tile, stone or concrete
block, which are bonded together with mortar to form a
masonry element such as walls, columns, piers, buttress,
etc. |
| NOMINAL
DIMENSIONS | Specified dimensions plus the thickness of the joint with
which the unit is laid. |
| PANEL WALL | An exterior non-load bearing wall in framed structure,
supported at each storey but subject to lateral loads. |
| PARTITION
WALL | An interior non-load bearing wall, one storey or part
storey in height. |
| PIER | A projection from either or both sides of a wall forming an
integral part of the wall and conforming to the
requirement of Sec 7.4.3.3 of this Chapter. |
| PILASTER | A thickened section forming integral part of a wall placed
at intervals along the wall, to increase the stiffness of the
wall or to carry a vertical concentrated load. Thickness of
a pier is the overall thickness including the thickness of
the wall or, when bounded into a limb of cavity wall, the
thickness obtained by treating that limb as an
independent wall. |
| PRISM | An assemblage of masonry units bonded by mortar with
or without grout used as a test specimen for determining
properties of masonry. |
| REINFORCED
MASONRY | The masonry construction, in which reinforcement acting
in conjunction with the masonry is used to resist forces
and is designed in accordance with Sec 7.6 of this Chapter. |
| SHEAR WALL | A load bearing wall designed to carry horizontal forces
acting in its own plane with or without vertical imposed
loads. |
| SOLID UNIT | A masonry unit whose net cross-sectional area in any
plane parallel to the bearing surface is 75 percent or more
of the gross cross-sectional area in the same plane. |
| SPECIFIED
DIMENSIONS | The dimensions specified for the manufacture or
construction of masonry, masonry units, joints or any
other components of a structure. Unless otherwise stated,
all calculations shall be made using or based on specified
dimensions. |
| STACK BOND | A bond in bearing and nonbearing walls, except veneered
walls, in which less than 75 percent of the units in any
transverse vertical plane lap the ends of the units below a
distance less than one-half the height of the unit, or less
than one-fourth the length of the unit. |
| VENEERED WALL | A wall in which the facing is attached to the backing but
not so bonded as to result in a common action under load. |
| WALL JOINT | A vertical joint parallel to the face of the wall. |
| WALL TIE | A metal fastener which connects wythes of masonry to
each other or to other materials. |
| WYTHE | Portion of a wall which is one masonry unit in thickness. |
### 7.1.3 Symbols and Notation
The following units shall be generally implicit in this Chapter for the corresponding quantities:
| Lengths | mm |
| ----------------- | -------------- |
| Areas | mm2 |
| Moment of inertia | mm4 |
| Force | N |
| Moment, torsion | N mm |
| Stress, strength | N/mm² |
* $A_b$ = Cross-sectional area of anchor bolt
* $A_e$ = Effective area of masonry
* $A_g$ = Gross area of wall
* $A_{mv}$ = Net area of masonry section bounded by wall thickness and length of section in the direction of shear force considered
* $A_p$ = Area of tension (pullout) cone of an embedded anchor bolt projected into the surface of masonry
* $A_s$ = Effective cross-sectional area of reinforcement in a flexural member
* $A_v$ = Area of steel required for shear reinforcement perpendicular to the longitudinal reinforcement
| $A_s'$ | = | Effective cross-sectional area of compression reinforcement in a
flexural member |
| --------------- | - | ------------------------------------------------------------------------------------------------------------------------- |
| $B_a$ | = | Allowable tension force on anchor bolt |
| $B_v$ | = | Computed shear force on anchor bolt |
| $C_d$ | = | Masonry shear strength coefficient |
| $E_m$ | = | Modulus of elasticity of masonry |
| $E_s$ | = | Modulus of elasticity of steel |
| $F$ | = | Loads due to weight and pressure of fluids or related moments
and forces |
| $F_a$ | = | Allowable average axial compressive stress for centroidally
applied axial load only |
| $F_b$ | = | Allowable flexural compressive stress if members were carrying
bending load only |
| $F_{br}$ | = | Allowable bearing stress |
| $F_s$ | = | Allowable stress in reinforcement |
| $F_{sc}$ | = | Allowable compressive stress in column reinforcement |
| $F_t$ | = | Allowable flexural tensile stress in masonry |
| $F_v$ | = | Allowable shear stress in masonry |
| $G$ | = | Shear modulus of masonry |
| $h$ | = | Actual height between lateral supports |
| $h_o$ | = | Height of opening |
| $I$ | = | Moment of inertia about the neutral axis of the cross-sectional
area |
| $I_g, I_{cr}$ | = | Gross, cracked moment of inertia of the wall cross-section |
| $L$ | = | Actual length of wall |
| $M$ | = | Design moment |
| $M_c$ | = | Moment capacity of the compression steel in a flexural member
about the centroid of the tensile force |
| $M_{cr}$ | = | Cracking moment strength of the masonry wall |
| $M_m$ | = | The moment of the compressive force in the masonry about the
centroid of the tensile force in the reinforcement |
| $M_n$ | = | Nominal moment strength of the masonry wall |
| $M_s$ | = | The moment of the tensile force in the reinforcement about the
centroid of the compressive force in the masonry |
| $M_{ser}$ | = | Service moment at the mid-height of the panel, including P-Delta
effects |
| $M_u$ | = | Factored moment |
| $P$ | = | Design axial load |
| $P_a$ | = | Allowable centroidal axial load for reinforced masonry columns |
| $P_b$ | = | Nominal balanced design axial strength |
| $P_{dl}$ | = | Load from tributary floor or roof area |
| $P_n$ | = | Nominal axial load strength with bending |
| $P_u$ | = | Factored axial load |
| $P_{ud}$ | = | Factored load from tributary floor or roof loads |
| $P_{uw}$ | = | Factored weight of the wall tributary to the section under
consideration |
| $P_w$ | = | Weight of the wall tributary to the section under consideration |
| $S$ | = | Section modulus |
| $V$ | = | Total design shear force |
| $V_m$ | = | Nominal shear strength provided by masonry |
| $V_n$ | = | Nominal shear strength |
| $V_s$ | = | Nominal shear strength provided by shear reinforcement |
| $a$ | = | Depth of equivalent rectangular stress block for strength design |
| $b$ | = | Effective width of rectangular member or width of flange for T
and I section |
| $b_a$ | = | Computed tension force on anchor bolt |
| $b_v$ | = | Allowable shear force on anchor bolt |
| $b_w$ | = | Width of web in T and I member |
| $c$ | = | Distance from the neutral axis to extreme fibre |
| $d$ | = | Distance from the compression face of a flexural member to the
centroid of longitudinal tensile reinforcement |
| $d_b$ | = | Diameter of the reinforcing bar, diameter of bolt |
| $e$ | = | Eccentricity of $P_u$ |
| $\epsilon_{mu}$ | = | Maximum usable compressive strain of masonry |
| $f_a$ | = | Computed axial compressive stress due to design axial load |
| $f_b$ | = | Computed flexural stress in the extreme fibre due to design
bending load only |
| $f_{md}$ | = | Computed compressive stress in masonry due to dead load only |
| $f_r$ | = | Modulus of rupture |
| $f_s$ | = | Computed stress in reinforcement due to design load |
| $f_y$ | = | Tensile yield stress of reinforcement |
| $f_v$ | = | Computed shear stress due to design load |
| $f'_m$ | = | Specified compressive strength of masonry at the age of 28 days |
| $h$ | = | Height of wall between points of support |
| $h'$ | = | Effective height of a wall or column |
| $j$ | = | Ratio or distance between centroid of flexural compressive force
and centroid of tensile forces to depth, $d$ |
| $k$ | = | Ratio of depth of the compression zone in flexural member to
depth, $d$; stiffening coefficient |
| $l$ | = | Length of a wall or segment |
| $l_b$ | = | Embedment depth of anchor bolt |
| $l_{be}$ | = | Anchor bolt edge distance, the least length measured from the
edge of masonry to the surface of the anchor bolt |
| $l_d$ | = | Required development length of reinforcement |
| $n$ | = | Modular ratio = $E_s / E_m$ |
| $r_e$ | = | Ratio of the area of bars cut off to the total area of bars at the
section |
| $s$ | = | Spacing of stirrups or bent bars in a direction parallel to that of
the main reinforcement |
| $t$ | = | Effective thickness of a wythe, wall or column |
| $u$ | = | Bond stress per unit of surface area of bar |
| $\Delta_u$ | = | Horizontal deflection at mid-height under factored load; P-Delta
effects shall be included in deflection calculation |
| $\Sigma o$ | = | Sum of the perimeters of all the longitudinal reinforcement |
| $\rho$ | = | Steel ratio = $A_s / bd$ |
| $\rho_n$ | = | Ratio of distributed shear reinforcement on a plane
perpendicular to the plane of $A_{mv}$ |
| $\phi$ | = | Strength reduction factor. |
## 7.2 Materials
### 7.2.1 General
All materials used in masonry construction shall conform to the requirements specified in Part 5 of this Code. If no requirements are specified for a material, quality shall be based on generally accepted good practice, subject to the approval of the building official.
### 7.2.2 Masonry Units
The following types of masonry units which conform to the standards mentioned in Sec 2.2.4 of Part 5 may be used in masonry construction:
* (a) Common building clay bricks
* (b) Burnt clay hollow bricks
* (c) Burnt clay facing bricks
* (d) Hollow concrete blocks
Other types of masonry units conforming to Sec 2.2.4 of Part 5 may also be used.
### 7.2.3 Mortar and Grout
Mortar and grout for masonry construction shall conform to the requirements specified in Part 5 of this Code. Mix proportions and compressive strength of some commonly used mortars are given in Table 6.7.1.
## 7.3 Allowable Stresses
### 7.3.1 General
Stresses in masonry shall not exceed the values given in this Section. All allowable stresses for working stress design may be increased one third when considering wind or earthquake forces either acting alone or combined with vertical loads. No increase shall be allowed for vertical loads acting alone.
r1
### 7.3.2 Specified Compressive Strength of Masonry, r1
The allowable stresses for masonry construction shall be based on the value of fras determined by Sec 7.3.3 below.
Table 6.7.1: Mix Proportion and Strength of Commonly used Mortars
| Grade of | Mix Proportion by Volume1, 2 | Minimum Compressive Strength at |
| -------- | --------------------------------------- | ------------------------------- |
| Mortar | | 28 days, N/mm² |
| | Cement
Sand | |
| M1 | 3 | 10 |
| M2 | 4 | 7.5 |
| M3 | 1
5 | 5 |
| M4 | 6 | 3 |
| M5 | 7 | 2 |
| M6 | 8 | 1 |
* 1 Sand and cement shall be measured in loose volume and sand shall be well graded with a minimum F.M. of 1.20
* 2 Lime to a maximum of one fourth (1/4) part by volume of cement may be used to increase workability.
### 7.3.3 Compliance with r1
Compliance with the requirements for the specified compressive strength of masonry, '\_m\$ shall be in accordance with the following:
#### 7.3.3.1
Masonry Prism Testing: The compressive strength of masonry based on tests at 28 days in accordance with "Standard Test Method for Compressive Strength of Masonry Prisms", (ASTM E447) for each set of prisms shall equal or exceed '\_m\$ . Verification by masonry prism testing shall meet the following :
* (a) Testing Prior to Construction: A set of five masonry prisms shall be built and tested in accordance with ASTM E447 prior to the start of construction. Materials used for prisms shall be same as used in the project. Prisms shall be constructed under the observation of the engineer or an approved agency and tested by an approved agency.
* (b) Testing During Construction: When full allowable stresses are used in design, a set of three prisms shall be built and tested during construction in accordance with (ASTM E447) for each 500 square meters of wall area, but not less than one set of three masonry prisms for any project. No testing during construction shall be required when 50% of the allowable stresses are used in design.
### 7.3.4 Quality Control
Quality control shall include, but not be limited to assure that:
* (a) Masonry units, reinforcement, cement, lime, aggregate and all other materials meet the requirements of the applicable standard of quality and that they are properly stored and prepared for use.
* (b) Mortar and grout are properly mixed using specified proportions of ingredients. The method of measuring materials for mortar and grout shall be such that proportions of materials are controlled.
* (c) Construction details, procedures and workmanship are in accordance with the plans and specification.
* (d) Placement, splices and bar diameters are in accordance with the provisions of this Chapter and the plans and specifications.
### 7.3.5 Allowable Stresses in Masonry
When the quality control provisions specified in Sec 7.3.4 above do not include requirements for special inspection, the allowable design stresses in this Section shall be reduced by 50 percent.
* (a) Axial Compressive Stress
* (i) Unreinforced masonry walls, columns and reinforced masonry wall
(ii) Reinforced masonry columns
(b) Compressive Stress in Flexural
* (c) Tensile Stress of Walls in Flexure
The allowable tensile stress for walls in flexure of masonry structures without tensile reinforcement using mortar Type M1 or M2 shall not exceed the values specified in Tables 6.7.2 and 6.7.3. For Types M3 and M4 mortar, the values shall be reduced by 25 percent.
No tension is allowed across head joints in stack bond masonry. Values for tension normal to head joints are for running bond. These values shall not be used for horizontal flexural members such as beams, girders or lintels.
Table 6.7.2: Flexural Tension, Ft
| Masonry | Normal to Bed Joints | Normal to Head Joints |
| ---------------------------------------------- | -------------------- | --------------------- |
| | N/mm² | N/mm² |
| Solid Units | 0.20 | 0.40 |
| Hollow Units | 0.12 | 0.25 |
| Table 6.7.3: Tension Normal to Head Joints, Ft | | |
| Masonry | Clay Units | Concrete Units |
| ------------ | ---------- | -------------- |
| | N/mm² | N/mm² |
| Solid Units | 0.35 | 0.40 |
| Hollow Units | 0.22 | 0.25 |
* (d) Reinforcing Bond Stress, u
Plain Bars: 0.30 N/mm²
Deformed Bars: 1.0 N/mm²
* (e) Shear Stress for Flexural Members, $F_v$
* (i) When no shear reinforcement is used
* (i) When shear reinforcement is not provided to resist entire shear force, $F_v = 0.083 \sqrt{f'_m} \le 0.25$ N/mm$^2$ (6.7.4)
* (ii) When shear reinforcement is designed to take entire shear force, $F_v = 0.25 \sqrt{f'_m} \le 0.75$ N/mm$^2$ (6.7.5)
* (f) Shear Stress for Shear Walls, $F_v$
* (i) Unreinforced masonry
For clay units:
$$
F_v = 0.025\sqrt{f_m'} \leq 0.40 \text{ N/mm}^2 \tag{6.7.6}
$$
For concrete units:
* M1 or M2 Mortar: 0.20 N/mm2 M3 Mortar: 0.12 N/mm2
* (ii) The allowable shear stress for reinforced masonry shear walls shall be according to Table 6.7.4.
Table 6.7.4: Allowable Shear Stress for Reinforced Masonry Shear Walls, $F_v$
| Masonry Wall | M/Vd | $F_v$, N/mm² | Maximum Allowable N/mm² |
| ---------------------------------------- | -------- | ------------------------------------------------------ | ----------------------------------- |
| Masonry
taking all
shear | $<1$ | $\dfrac{1}{36}\left(4-\dfrac{M}{Vd}\right)\sqrt{f_m'}$ | $\left(0.4-0.2\dfrac{M}{Vd}\right)$ |
| Masonry
taking all
shear | $\geq 1$ | $0.083\sqrt{f_m'}$ | 0.17 |
| Reinforcement
taking all
shear | $<1$ | $\dfrac{1}{24}\left(4-\dfrac{M}{Vd}\right)\sqrt{f_m'}$ | $\left(0.6-0.2\dfrac{M}{Vd}\right)$ |
| Reinforcement
taking all
shear | $\geq 1$ | $0.125\sqrt{f_m'}$ | 0.37 |
### 7.3.6 Allowable Stresses in Reinforcement
* (a) Tensile Stress
* (i) Deformed bars,
$$
F_s = 0.5f_y \leq 165\ \text{N/mm}^2 \tag{6.7.7}
$$
* (ii) Ties, anchors and plain bars,
$$
F_s = 0.4f_y \leq 135\ \text{N/mm}^2 \tag{6.7.8}
$$
* (b) Compressive Stress
* (i) Deformed bars in columns and shear walls,
$$
F_{sc} = 0.4f_y \leq 165\ \text{N/mm}^2 \tag{6.7.9}
$$
* (ii) Deformed bars in flexural members
$$
F_{sc} = 0.5f_y \leq 165\ \text{N/mm}^2 \tag{6.7.10}
$$
### 7.3.7 Combined Compressive Stress
Members subject to combined axial and flexural stresses shall be designed in accordance with accepted principles of mechanics or in accordance with the following formula:
$$
\frac{f_a}{F_a} + \frac{f_b}{F_b} \leq 1 \tag{6.7.11}
$$
### 7.3.8 Modulus of Elasticity
The modulus of elasticity of masonry shall be determined by the secant method. The slope of the line connecting the points $0.05f_m'$ and $0.33f_m'$ on the stressstrain curve shall be taken as the modulus of elasticity of masonry. If required, actual values shall be established by tests. These values are not to be reduced by 50 per cent as specified in Sec 7.3.5(a).
* (a) Modulus of Elasticity for Masonry
$$
E_m = 750f_m' \leq 15{,}000\ \text{N/mm}^2 \tag{6.7.12}
$$
* (b) Modulus of Elasticity for Steel
$$
E_s = 2{,}00{,}000\ \text{N/mm}^2 \tag{6.7.13}
$$
* (c) Shear Modulus of Masonry
$$
G = 0.4E_m\ \text{N/mm}^2 \tag{6.7.14}
$$
### 7.3.9 Shear and Tension on Embedded Anchor Bolts
#### 7.3.9.1
Allowable loads and placement requirements for anchor bolts shall be in accordance with the following:
* (a) Bent bar anchor bolts shall have a hook with a 90o bend with an inside diameter of $3d_b$ plus an extension of $1.5d_b$ at the free end.
* (b) Headed anchor bolts shall have a standard bolt head.
* (c) Plate anchor bolts shall have a plate welded to the shank to provide anchorage equivalent to headed anchor bolts.
#### 7.3.9.2
The effective embedment length, $l_b$ for bent bar anchors shall be the length of embedment measured perpendicular from the surface of the masonry to the bearing surface of the bent end minus one anchor bolt diameter. For plate or headed anchor bolts $l_b$ shall be the length of embedment measured perpendicular from the surface of the masonry to the bearing surface of the plate or head of the anchorage. All bolts shall be grouted in place with at least 25 mm of grout between the bolt and the masonry except that 6 mm diameter bolts may be placed in bed joints which are at least twice as thick as the diameter of the bolt.
#### 7.3.9.3 Allowable shear force
Allowable loads in shear shall be according to Table 6.7.5 or lesser of the value obtained from the following formulae:
$$
B_v = 1070(f_m'A_b)^{1/4} \tag{6.7.15}
$$
$$
B_v = 0.12A_bf_y \tag{6.7.16}
$$
When the distance $l_{be}$ is less than $12d_b$, the value of $B_v$ in Eq. 6.7.15 shall be reduced to zero at a distance $l_{be}$ equal to 40 mm. Where adjacent anchors are spaced closer than $8d_b$, the allowable shear of the adjacent anchors determined by Eq. 6.7.15 shall be reduced by interpolation to 0.75 times the allowable shear value at a centre to centre spacing of $4d_b$.
#### 7.3.9.4 Allowable tension
Allowable tension shall be the lesser value selected from Table 6.7.6 and Table 6.7.7 or shall be determined from lesser of the values obtained from the following formulae:
$$
B_t = 0.04A_p\sqrt{f_m'} \tag{6.7.17}
$$
$$
B_t = 0.2A_bf_y \tag{6.7.18}
$$
The area $A_p$ shall be the lesser of the area obtained from Equations 6.7.17 and 6.7.18 and where the projected areas of adjacent anchor bolts overlap, $A_p$ of each anchor bolt shall be reduced by 50 percent of the overlapping area.
$$
A_p = \pi l_b^2 \tag{6.7.19}
$$
$$
A_p = \pi l_{be}^2 \tag{6.7.20}
$$
Table 6.7.5: Allowable Shear, Bv for Embedded Anchor Bolts for Masonry, kN\*
| | | B | ent Bar Anc | hor Bolt D | iameter, m | m | |
| ---------------------------- | --- | --- | ----------- | ---------- | ---------- | ---- | ---- |
| $f_m'$
N/mm2 | 10 | 12 | 16 | 20 | 22 | 25 | 28 |
| 10 | 2.0 | 3.7 | 5.9 | 7.9 | 8.5 | 9.1 | 9.6 |
| 12 | 2.0 | 3.7 | 5.9 | 8.2 | 8.3 | 9.5 | 10.1 |
| 13 | 2.0 | 3.7 | 5.9 | 8.5 | 9.2 | 9.8 | 10.4 |
| 17 | 2.0 | 3.7 | 5.9 | 8.5 | 9.7 | 10.3 | 11.0 |
| 20 | 2.0 | 3.7 | 5.9 | 8.5 | 10.1 | 10.8 | 11.5 |
| 27 | 2.0 | 3.7 | 5.9 | 8.5 | 10.9 | 11.6 | 12.3 |
* Values are for bolts of at least ASTM A307 quality. Bolts shall be those specified in Sec 4.3.9.1.
Table 6.7.6: Allowable Tension, 7 for Embedded Anchor Bolts for Masonry, kN1, 2
| | | Embedm | ent Lengt | h,or Edg | e Distance | ,8mm | |
| ----------------- | --- | ------ | --------- | -------- | ---------- | ---- | ---- |
| $f_m'$
N/mm² | 50 | 75 | 100 | 125 | 150 | 200 | 250 |
| 10 | 1.0 | 2.4 | 4.3 | 6.7 | 9.7 | 17.3 | 27.0 |
| 12 | 1.2 | 2.6 | 4.7 | 7.4 | 10.6 | 18.9 | 29.6 |
| 13 | 1.2 | 2.8 | 5.0 | 7.8 | 11.2 | 20.0 | 31.2 |
| 17 | 1.3 | 3.1 | 5.6 | 8.7 | 12.6 | 22.4 | 35.0 |
| 20 | 1.5 | 3.4 | 6.7 | 9.5 | 13.8 | 24.5 | 38.2 |
| 27 | 1.7 | 3.9 | 7.0 | 11.0 | 15.9 | 28.3 | 44.1 |
* 1 The allowable tension values are based on compressive strength of masonry assemblages. Where yield strength of anchor bolt steel governs, the allowable tension is given in Table 6.7.7.
* 2 Values are for bolts of at least ASTM A307 quality. Bolts shall be those specified in Sec 7.3.9.1.
Table 6.7.7: Allowable Tension, 7 for Embedded Anchor Bolts for Masonry, kN1
| | | Bent Ba | r Anchor B | olt Diame | ter, mm | | |
| ----------- | ------------- | -------------- | ---------- | -------------- | -------------- | ----------- | ---------- |
| 6 | 10 | 12 | 16 | 20 | 22 | 25 | 28 |
| 1.5 | 3.5 | 6.2 | 9.8 | 14.1 | 19.2 | 25.1 | 31.8 |
| 1 Values ar | e for bolts o | f at least AST | M A307 qua | lity. Bolts sh | all be those s | pecified in | Sec 7.3.9. |
#### 7.3.9.5 Combined shear and tension
Anchor bolts subjected to combined shear and tension shall be designed in accordance with the formula given below:
#### 7.3.9.6 Minimum edge distance, $l_{be}$
The minimum value of $l_{be}$ measured from the edge of the masonry parallel to the anchor bolt to the surface of the anchor bolt shall be 40 mm.
#### 7.3.9.7 Minimum embedment depth, $l_b$
The minimum embedment depth $l_b$ shall be $4d_b$ but not less than 50 mm.
#### 7.3.9.8 Minimum spacing between bolts
The minimum centre to centre spacing between anchors shall be $4d_b$.
### 7.3.10 Load Test
For load test, the member shall be subject to a superimposed load equal to twice the design live load plus one-half of the dead load. This load shall be maintained for a period of 24 hours. If, during the test or upon removal of the load, the member shows evidence of failure, such changes or modifications as are necessary to make the structure adequate for the rated capacity shall be made; or where possible, a lower rating shall be established. A flexural member shall be considered to have passed the test if the maximum deflection at the end of the 24 hour period neither exceeds $0.005\ell$ nor $0.00025\ell^2/t$ and the beam and slabs show a recovery of at least 75 percent of the observed deflection within 24 hours after removal of the load.
### 7.3.11 Reuse of Masonry Units
Masonry units may be reused when clean, unbroken and conforms to the requirements of Part 5. All structural properties of masonry of reclaimed units, especially adhesion bond, shall be determined by approved test. The allowable working stress shall not exceed 50 percent of that permitted for new masonry units of the same properties.
## 7.4 Basic Design Requirements
### 7.4.1 General
Masonry structures shall be designed according to the provisions of this Section. The required design strengths of masonry materials and any special requirements shall be specified in the plan submitted for approval.
### 7.4.2 Design Considerations
#### 7.4.2.1
Masonry structures shall be designed based on working stress and linear stress-strain distribution. Requirements for working stress design of unreinforced and reinforced masonry structures are provided in Sections 4.5 and 4.6 respectively. In lieu of the working stress design method, slender walls and shear walls may be designed by the strength design method specified in Sec 7.7.
The structure shall be proportioned such that eccentricity of loading on the members is as small as possible. Eccentric loading shall preferably be avoided by providing:
* (a) adequate bearing of floor/roof on the walls
* (b) adequate stiffness in slabs, and
* (c) fixity at the supports.
#### 7.4.2.2 Effective height
* (a) Wall: The effective height of a wall shall be taken as the clear height between the lateral supports at top and bottom in a direction normal to the axis considered. For members not supported at the top normal to the axis considered, the effective height is twice the height of the member above the support. Effective height less than the clear height may be used if justified.
* (b) Column: Effective height of the column shall be taken as actual height for the direction it is laterally supported and twice the actual height for the direction it is not laterally supported at the top normal to the axis considered.
* (c) Opening in Wall: When openings occur in a wall such that masonry between the openings is by definition a column, effective height of masonry between the openings shall be obtained as follows:
* (i) When wall has full restraint at the top, effective height for the direction perpendicular to the plane of wall equals 0.75… plus 0.25…r , where … is the distance between supports and …r is the height of the taller opening; and effective height for the direction parallel to the wall equals ….
* (ii) When wall has partial restraint at the top and bottom, effective height for the direction perpendicular to the plane of wall equals … when height of neither opening exceeds 0.5… and it is equal to 2… when height of any opening exceeds0.5…; and effective height for the direction parallel to the plane of the wall equals 2….
#### 7.4.2.3 Effective length
Effective length of a wall for different support conditions shall be as given in Table 6.7.8.
#### 7.4.2.4 Effective thickness
The effective thickness of walls and columns for use in the calculation of slenderness ratio, shall be defined as follows:
* (a) Solid Walls: The effective thickness of solid walls, faced walls or grouted walls shall be the specified thickness of the wall.
* (b) Solid Walls with Raked Mortar Joints: The effective thickness of solid walls with raked mortar joints shall be the minimum thickness measured at the joint.
* (c) Cavity Walls: When both limbs of a cavity wall are axially loaded, each limb shall be considered independently and the effective thickness of each limb shall be determined as in (a) or (b) above. If one of the limbs is axially loaded, the effective thickness of the cavity wall shall be taken as the square root of the sum of the squares of the effective thicknesses of the limbs.
* (d) Walls Stiffened by Pilasters: When solid or cavity walls are stiffened by pilasters at intervals, the effective thickness to be used for the calculation of $h'/t$ ratio shall be determined as follows:
* (i) Solid Walls: For stiffened solid walls the effective thickness shall be the specified thickness multiplied by the stiffening coefficient, k, values of which are given below:
| $S_p / w_p$ | Stiffening Coefficient, $k$\* for $t_p / t_w = 1$ | $t_p / t_w = 2$ | $t_p / t_w = 3$ |
| ----------- | ------------------------------------------------- | --------------- | --------------- |
| 6 | 1.0 | 1.4 | 2.0 |
| 8 | 1.0 | 1.3 | 1.7 |
| 10 | 1.0 | 1.2 | 1.4 |
| 15 | 1.0 | 1.1 | 1.2 |
| 20 or more | 1.0 | 1.0 | 1.0 |
* Linear interpolation is permitted for obtaining intermediate values of k
- Where, $S_p$ = centre to centre spacing of pilasters
- $t_p$ = thickness of pilaster including the wall
- $t_w$ = specified thickness of main wall
- $w_p$ = width of pilaster in the direction of wall
- (ii) Cavity Walls: When one or both limbs of a cavity wall are adequately bonded into pilasters at intervals, the effective thickness of each limb shall be determined separately as in (a), (b) or d above and the effective thickness of the stiffened cavity wall shall be determined in accordance with (c) above.
Where slenderness ratio of the wall is based on the effective length, the effective thickness shall be the same as that without pilasters.
* (e) Columns: The effective thickness for rectangular columns in the direction considered is the actual thickness provided in that direction. The effective thickness for nonrectangular columns is the thickness of a square column with the same moment of inertia about its axis as that about the axis considered in the actual column.
Table 6.7.8: Effective Length of Walls
| Support Condition | Effective Length |
| --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------- |
| Where a wall is continuous and is supported by cross wall and there is no
opening within a distance of $H/8$ from the face of cross wall. OR, | |
| Where a wall is continuous and is supported by pier/buttresses
conforming to Sec 7.4.3.3 (c). | $0.8L$ |
| Where a wall is supported by cross wall at one end and continuous with
cross wall at other end. OR, | |
| Where a wall is supported by pier/buttresses at one end and continuous
with pier/buttresses at other end conforming to Sec 7.4.3.3 (c). | $0.9L$ |
| Where a wall is supported at each end by cross wall. OR,
Where a wall is supported at each end by pier/buttresses conforming to
Sec 7.4.3.3 (c). | $1.0L$ |
| Where a wall is free at one end and continuous with a cross wall at the
other end. OR,
Where a wall is free at one end and continuous with a pier/buttresses at
the other end conforming to Sec 7.4.3.3 (c). | $1.5L$ |
| Where a wall is free at one end and supported at the other end by a cross
wall. OR, | $2.0L$ |
| Where a wall is free at one end and supported at the other end by a
pier/buttresses conforming to Sec 7.4.3.3 (c). | $2.0L$ |
#### 7.4.2.5 Slenderness ratio
* (a) Walls: For a wall, slenderness ratio shall be the ratio of effective height to effective thickness or effective length to effective thickness whichever less is. In case of a load bearing wall, slenderness ratio shall not exceed 20.
* (b) Column: For a column, slenderness ratio shall be taken to be the greater of the ratio of effective heights to the respective effective thickness in the two principal directions. Slenderness ratio for a load bearing column shall not exceed 12.
#### 7.4.2.6 Effective area
The effective cross-sectional area shall be based on the minimum bedded area of the hollow units, or the gross area of solid units plus any grouted area. If hollow units are used perpendicular to the direction of stress, the effective area shall be lesser of the minimum bedded area or the minimum cross-sectional area. If bed joints are raked, the effective area shall be correspondingly reduced. Effective areas for cavity walls shall be that of the loaded wythes.
#### 7.4.2.7 Flexural resistance of cavity walls
For computing the flexural resistance, lateral loads perpendicular to the plane of the wall shall be distributed to the wythes according to their respective flexural rigidities.
#### 7.4.2.8 Effective width of intersecting walls
Where a shear wall is anchored to an intersecting wall or walls, the width of the overhanging flange formed by the intersected walls on either side of the shear wall shall not exceed 6 times the thickness of the intersected wall. Limits of the effective flange may be waived if justified. Only the effective area of the wall parallel to the shear forces may be assumed to carry horizontal shear.
### 7.4.3 Supports
#### 7.4.3.1 Vertical support
Structural members providing vertical support of masonry shall provide a bearing surface on which the initial bed joint shall not be less than 6 mm or more than 25 mm and shall be of noncombustible materials, except where masonry is a nonstructural decorative feature or wearing surface.
#### 7.4.3.2 Vertical deflection
Elements supporting masonry shall be designed so that their vertical deflection does not exceed 1/600 of the clear span under total loads. Lintels shall be supported on each end such that allowable stresses in the supporting masonry are not exceeded. The minimum bearing length shall be 100 mm.
#### 7.4.3.3 Lateral support
* (a) Lateral support of masonry may be provided by cross walls, columns, piers, counter forts or buttresses when spanning horizontally or by floors, beams or roofs when spanning vertically.
* (b) Lateral supports for a masonry element such as load bearing wall or column shall be provided to
* (i) limit the slenderness of a masonry element so as to prevent or reduce possibility of buckling of the member due to vertical loads; and
* (ii) resist the horizontal components of forces so as to ensure stability of a structure against overturning.
* (c) From consideration of slenderness (i.e. requirement b(i) above), masonry elements may be considered to be laterally supported if
* (i) in case of a wall, where slenderness ratio is based on effective height, floor/roof slab (or beams and slab) irrespective of the direction of span, bears on the supported wall as well as cross walls, to the extent of at least 100 mm;
* (ii) in case of a wall, when slenderness ratio is based on its effective length, a cross wall/pier/buttress of thickness equal to or more than half the thickness of the supported wall or 125 mm, whichever is more and average length equal to or more than one-fifth of the height of the wall, is built at right angle to the wall and properly bonded;
* (iii) in case of a column, an RC or timber beam/RS joist/roof truss, is supported on the column. In this case, the column will not be considered to be laterally supported in the direction at right angle to it; and
* (iv) in case of a column, an RC beam forming a part of beam and slab construction, is supported on the column, and the slab adequately bears on stiffening walls. This construction will provide lateral support to the column, in the direction of both horizontal axes.
### 7.4.4 Stability
A wall or column subject to vertical and lateral loads may be considered to provide adequate lateral support from consideration of stability, if the construction providing the support is capable of resisting the following forces:
* (a) Simple static reactions at the point of lateral support to all the lateral loads; plus
* (b) A lateral load equal to 2.5% of the total vertical load that the wall or column is designated to carry at the point of lateral support.
#### 7.4.4.1
In case of load bearing buildings up to five storeys, stability requirements may be considered to have been satisfied if the following conditions are met.
* (a) Height to width ratio of building does not exceed 2.
* (b) Cross walls acting as stiffening walls continuous from outer wall to outer wall or outer wall to a load bearing inner wall, and of thickness and spacing as given in Table 6.7.9 are provided.
If stiffening wall or walls that are in a line, are interrupted by openings, length of solid wall or walls in the zone of the wall that is to be stiffened shall be at least one-fifth of the height of the opening.
* (c) Floors and roof either bear on cross walls or are properly anchored to those walls such that all lateral loads are safely transmitted to those walls and through them to the foundation.
* (d) Cross walls are built jointly with the bearing walls and jointly mortared, or interconnected by toothing.
Cross walls may be anchored to walls to be supported by ties of noncorrosive metal of minimum section 6 x 35 mm and length 60 mm with ends bent at least 50 mm, maximum vertical spacing of ties being 1.2 m.
Table 6.7.9: Thickness and Spacing of Stiffening Walls
| Thickness of Load | Height of | | StiffeningWall \* | |
| ------------------------------------------- | ---------------------------------- | ----------------------------------------- | ------------------------------------------- | ----------------------------- |
| Bearing Wall to be
Stiffened
(mm) | Storey not to
Exceed
(m) | Thickness n
1 to 3 storeys
(mm) | ot less than
4 and 5 storeys
(mm) | Maximum
spacing
(m) |
| 100 | 3.2 | 100 | - | 4.5 |
| 200 | 3.2 | 100 | 200 | 6.0 |
| 300 | 3.4 | 100 | 200 | 8.0 |
| above 300 | 5.0 | 100 | 200 | 8.0 |
* Storey height and maximum spacing as given are centre to centre dimensions.
#### 7.4.4.2
In case of walls exceeding 8 m in length, safety and adequacy of lateral supports shall always be checked by structural analysis.
#### 7.4.4.3
A trussed roofing may not provide lateral support unless special measures are adopted to brace and anchor the roofing. However, in case of residential and similar buildings of conventional design with trussed roofing having cross walls, it may be assumed that stability requirements are met by the cross walls and structural analysis for stability may be dispensed with.
#### 7.4.4.4
In case of walls exceeding 8 m in length, safety and adequacy of lateral supports shall always be checked by structural analysis.
#### 7.4.4.5
A trussed roofing may not provide lateral support unless special measures are adopted to brace and anchor the roofing. However, in case of residential and similar buildings of conventional design with trussed roofing having cross walls, it may be assumed that stability requirements are met by the cross walls and structural analysis for stability may be dispensed with.
#### 7.4.4.6
In case of external walls of basement and plinth, stability requirements of Sec 7.4.4 may be considered to be satisfied if :
* (a) Bricks used in basement and plinth have a minimum crushing strength of 5 N/mm² and mortar used in masonry is of Type M3 or better,
* (b) Clear height of ceiling in basement does not exceed 2.6 m,
* (c) In the zone of action of soil pressure on basement walls, traffic load excluding any surcharge due to adjoining buildings does not exceed 5 kN/m2 ,
* (d) Minimum thickness of basement walls is in accordance with Table 6.7.10.
In case there is surcharge on basement walls from adjoining buildings, thickness of basement walls shall be based on structural analysis.
Table 6.7.10: Minimum Thickness of Basement Wall
| Minimum Nominal | Height of the Ground above Basement |
| -------------------------- | ---------------------------------------- |
| Thickness of Basement Wall | Floor Level |
| (mm) | Wall Loading (Permanent Load) |
| | Less than 50 kN/m
More than 50 kN/m |
| 375 | 2.0 m
2.5 m |
| 250 | 1.4 m
1.8 m |
#### 7.4.4.7 Free standing wall
Free standing walls, subject to wind pressure or seismic forces shall be designed on the basis of permissible tensile stress in masonry or stability consideration. However in Seismic Zones 1 and 2, free standing walls may be proportioned without making any design calculations with the help of Table 6.7.11 provided the mortar used is of type not leaner than M3. For parapet wall see Sec 7.4.9.4.
### 7.4.5 Structural Continuity
Intersecting structural elements intended to act as a unit shall be anchored together to resist the design forces. Walls shall be anchored together to all floors, roofs or other elements which provide lateral support for the wall. Where floors or roofs are designed to transmit horizontal forces to walls, the anchorages to the walls shall be designed to resist the horizontal forces.
Table 6.7.11: Height to Thickness Ratio of Free Standing Wall
| Design Wind Pressure, N/m2 | Height to Thickness Ratio |
| -------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------- |
| Up to 300 | 10 |
| 600 | 7 |
| 900 | 5 |
| 1100 | 4 |
| Note: Height is to be taken from 150 mm below ground level or top of footing/ foundation block, whichever is higher, and up to the top edge of the wall. | |
#### 7.4.5.1 Multi-wythe Walls
All wythes shall be bonded by grout or tied together by corrosion resistant wall ties or joint reinforcement as follows:
* (a) Wall Ties in Cavity Wall Construction: Wall ties shall be of sufficient length to engage all wythes. The portion of the wall ties within the wythe shall be completely embedded in mortar or grout. The ends of the wall ties shall be bent to 90 degree angles with an extension not less than 50 mm long. Wall ties not completely embedded in mortar or grout between wythes shall be a single piece with each end engaged in each wythe.
There shall be at least one 6 mm diameter wall tie for each 0.45 m2 of wall area. For cavity walls in which the width of the cavity is greater than 75 mm, but not more than 115 mm, at least one 6 mm diameter wall tie for each 0.3 m2 of wall area shall be provided.
Ties in alternate courses shall be staggered. The vertical distance between ties shall not exceed 600 mm. The horizontal distance between ties shall not exceed 900 mm. Additional ties spaced not more than 900 mm apart shall be provided around and within 300 mm of the opening. Wall ties of different size and spacing may be used if they provide equivalent strength between wythes.
* (b) Wall Ties for Grouted Multi-wythe Construction: The two wythes shall be bonded together with at least 6 mm diameter steel wall ties for each 0.20 m2 of area. Wall ties of different size and spacing may be used if they provide equivalent strength between wythes.
* (c) Joint Reinforcement: Prefabricated joint reinforcement for masonry walls shall have a minimum of one cross wire of at least 3 mm diameter steel for each 0.2 m2 of wall area. The vertical spacing of the joint reinforcement shall not exceed 400 mm. The longitudinal wires shall be thoroughly embedded in the bed joint mortar. The joint reinforcement shall engage all wythes.
Where the space between tied wythes is filled with grout or mortar, the allowable stresses and other provisions for masonry bonded walls shall apply. Where the space is not filled, tied walls shall conform to the allowable stress, lateral support, thickness (excluding cavity), height and tie requirements of cavity walls.
### 7.4.6 Joint Reinforcement and Protection of Ties
The minimum mortar cover between ties or joint reinforcement and any exposed face shall be 15 mm. The thickness of grout or mortar between masonry units and joint reinforcement shall not be less than 6 mm, except that smaller diameter reinforcement or bolts may be placed in bed joints which are at least twice as thick as the diameter of the reinforcement.
### 7.4.7 Pipes and Conduits
Pipe or conduit shall not be embedded in any masonry so as to reduce the capacity to less than that necessary for required stability or required fire protection, except the following:
* (a) Rigid electrical conduit may be embedded in structural masonry when their location has been detailed on the approved plan.
* (b) Any pipe or conduit may pass vertically or horizontally through any masonry by means of a sleeve at least large enough to pass any hub or coupling on the pipeline. Such sleeves shall not be placed closer than three diameters, centre to centre, nor shall they unduly impair the strength of construction.
* (c) Placement of pipes or conduits in unfilled cores of hollow unit masonry shall not be considered as embedment.
### 7.4.8 Loads and Load Combination
#### 7.4.8.1 Design loads
All design loads and other forces to be taken for the design of masonry structures shall conform to Chapter 2, Loads.
#### 7.4.8.2 Load dispersion
The angle of dispersion of vertical load on walls shall be taken as not more than 30o from the vertical.
#### 7.4.8.3 Distribution of concentrated vertical loads in walls
The length of wall, laid up in running bond, which may be considered capable of working at the maximum allowable compressive stresses to resist vertical concentrated loads, shall not exceed the centre to centre distance between such loads, nor the width of bearing area plus four times the wall thickness. Concentrated vertical loads shall not be assumed distributed across continuous vertical mortar or control joints unless elements designed to distribute the concentrated vertical loads are employed.
#### 7.4.8.4 Loads on non-bearing wall
Masonry walls used as interior partition or as exterior surfaces of building which do not carry vertical loads imposed by other elements of the building shall be designed to carry their own weight plus any superimposed finish and lateral forces. Bonding or anchorage of nonbearing walls shall be adequate to support the walls and to transfer lateral forces to the supporting structures.
#### 7.4.8.5 Load combinations
Load combination for design of masonry structures shall conform to requirements of Sec 2.7 Chapter 2 Part 6.
### 7.4.9 Minimum Design Dimensions
#### 7.4.9.1 Minimum thickness of load bearing walls
The nominal thickness of masonry bearing walls in building shall not be less than 250 mm.
**Exception:**
Stiffened solid masonry bearing walls in one-storey buildings may have a minimum effective thickness of 165 mm when not over 3 m in height, provided that when gable construction is used an additional 1.5 m height may be permitted at the peak of the gable.
#### 7.4.9.2 Variation in thickness
When a change in thickness due to minimum thickness requirements occurs between floor levels, the greater thickness shall be carried up to the higher floor level.
#### 7.4.9.3 Decrease in thickness
When walls of masonry of hollow units or masonry bonded hollow walls are decreased in thickness, a course or courses of solid masonry shall be constructed between the walls below and the thinner wall above, or special units or construction shall be used to transmit the loads from wythes to the walls below.
#### 7.4.9.4 Parapet wall
Parapet walls shall be at least 200 mm thick and height shall not exceed 4 times the thickness. The parapet wall shall not be thinner than the wall below.
## 7.5 Design of Unreinforced Masonry
### 7.5.1 General
The requirements of this Section are applicable to unreinforced masonry in addition to the requirements of Sec 7.4.
### 7.5.2 Design of Members Subjected to Axial Compression
The stresses due to compressive forces applied at the centroid of any load bearing wall, column and pilaster may be computed by Eq. 6.7.22 below assuming uniform distribution over the effective area.
$$
f_a = \frac{P}{A_e} \tag{6.7.22}
$$
### 7.5.3 Design of Members Subjected to Combined Bending and Axial Compression
* (a) Compressive stresses due to combined bending and axial load shall satisfy the requirements of Sec 7.3.5.
* (b) Resultant tensile stress due to combined bending and axial load shall not exceed the allowable flexural tensile stress, $F_t$ as specified in Sec 7.3.
### 7.5.4 Design of Members Subjected to Flexure
Stresses due to flexure calculated by Eq. 6.7.23 below shall not exceed the values given in Sec 7.3.5.
$$
f_b = \frac{Mc}{I} \tag{6.7.23}
$$
### 7.5.5 Design of Members Subjected to Shear
Shear calculations in flexural members and shear walls shall be based on Eq. 6.7.24 below.
$$
f_v = \frac{V}{A_e} \tag{6.7.24}
$$
### 7.5.6 Design of Arches
Geometrical form and the cross-sectional dimensions of masonry arch shall be selected such that the line of thrust at any section of the arch is kept within the middle third of the section of the arch rib. The elastic theory of arches shall be permitted for the analysis of unreinforced masonry arches. All supports of arches shall be capable of developing the required horizontal thrust without suffering unacceptable displacements. Every arch must be designed to resist the stresses due to the following loads:
* (a) Gravity loads :
* (i) Dead loads shall be placed in conformity with their actual distribution.
* (ii) Live loads shall be positioned to cover entire span or part of the span as necessary to produce the maximum stresses at the crown, springing and all other sections of the arch rib.
* (b) Loads due to temperature change.
* (c) Shrinkage load due to setting and hardening.
* (d) Shortening of arch rib under thrust caused by loads.
### 7.5.7 Footings and Corbels
The slope of footing and corbelling (measured from the horizontal to the face of the corbelled surface) shall not be less than 60 degrees.
The maximum horizontal projection of corbelling from the plane of the wall shall be such that stress at any section does not exceed the allowable value.
## 7.6 Design of Reinforced Masonry
### 7.6.1 General
The requirements of this Section are in addition to those specified in Sec 7.4 and are applicable to reinforced masonry. Plain bars larger than 6 mm in diameter shall not be used.
#### 7.6.1.1 Assumptions
The following assumptions shall be applicable for this Section.
* (a) Masonry carries no tensile stress.
* (b) Reinforcement is completely surrounded by and bonded to masonry material so that they work together as a homogeneous material within the range of working stresses.
### 7.6.2 Design of Members Subjected to Axial Compression
Stresses due to compressive forces applied at the centroid of load bearing wall, column and pilaster may be computed assuming uniform distribution over the effective area. Stress shall be calculated from Eq. 6.7.25 below:
$$
f_a = \frac{P}{A_e} \tag{6.7.25}
$$
### 7.6.3 Design of Members Subjected to Combined Bending and Axial Compression
Stress due to combined bending and axial loads shall satisfy the requirements of Sec 7.3.5. Columns and walls subjected to bending with or without axial loads shall meet all applicable requirements for flexural design.
The design of walls with an $(h'/t)$ ratio larger than 30 shall be based on forces and moments determined from analysis of structure. Such analysis shall take into account influence of axial loads and variable moment of inertia on member stiffness and fixed end moments, effect of deflections on moments and forces, and the effects of duration of loads.
### 7.6.4 Design of Members Subjected to Shear Force
Shearing stresses in flexural members and shear walls shall be computed by
$$
f_v = \frac{V}{bjd} \tag{6.7.26}
$$
When the computed shear stress exceeds the allowable value, web reinforcement shall be provided and designed to carry the total shear force. Both vertical and horizontal shear stresses shall be considered. The area required for shear reinforcement placed perpendicular to the longitudinal reinforcement shall be computed by Eq. 6.7.27 below:
$$
A_v = \frac{sV}{F_sd} \tag{6.7.27}
$$
Spacing of vertical shear reinforcement shall not exceed d/2, nor 600 mm. Inclined shear reinforcement shall have a maximum spacing of $0.375d(1 + \cot\alpha)$, but not greater than 600 mm, where α is the acute angle between inclined bar and the horizontal.
### 7.6.5 Design of Members Subjected to Flexural Stress
#### 7.6.5.1 Rectangular elements
Rectangular flexural elements shall be designed in accordance with the following equations or other methods based on the simplified assumptions.
* (a) Compressive stress in the masonry:
$$
f_b = \frac{M}{bd^2}\left(\frac{2}{jk}\right) \tag{6.7.28}
$$
(b) Tensile stress in the longitudinal reinforcement:
$$
f_s = \frac{M}{A_sjd} \tag{6.7.29}
$$
(c) Design coefficients :
$$
k = [(np)^2 + 2np]^{1/2} - np \tag{6.7.30}
$$
Or,
$$
k = \frac{1}{1+\dfrac{f_s}{nf_b}} \tag{6.7.31}
$$
$$
j = 1 - \frac{k}{3} \tag{6.7.32}
$$
#### 7.6.5.2 Nonrectangular sections
Flexural elements of nonrectangular cross-section shall be designed in accordance with the assumptions given in Sec 7.4.2.1 and 7.6.1.1.
#### 7.6.5.3 Lateral support
The clear distance between lateral supports of a beam shall not exceed 32 times the least depth of compression area.
#### 7.6.5.4 Effective width
In computing flexural stresses in walls where reinforcement occurs, the effective width assumed for running bond masonry shall not exceed 6 times the nominal wall thickness or the centre to centre distance between reinforcement. Where stack bond is used, the effective width shall not exceed 3 times the nominal wall thickness or the centre to centre distance between reinforcement or the length of one unit, unless grouted solid using open-ended joints.
#### 7.6.5.5 Bond
In flexural members in which tensile reinforcement is parallel to the compressive face, the bond stress shall be computed by the formula:
$$
u = \frac{V}{\Sigma_o jd} \tag{6.7.33}
$$
### 7.6.6 Reinforcement Requirements and Details
#### 7.6.6.1 Column reinforcement
* (a) Vertical Reinforcement: The area of vertical reinforcement shall not be less than $0.005A_e$ and not more than $0.04A_e$. At least four 10 mm diameter bars shall be provided.
* (b) Lateral Ties: All longitudinal bars for columns shall be enclosed by lateral ties. Lateral support shall be provided to the longitudinal bars by the corner of a complete tie having an included angle of not more than 135 degrees or by a hook at the end of a tie. The corner bars shall have such support provided by a complete tie enclosing the longitudinal bars. Alternate longitudinal bars shall have such lateral support provided by ties and no bar shall be farther than 150 mm from such a laterally supported bar.
Lateral ties and longitudinal bars shall be placed not less than 40 mm and not more than 125 mm, from the surface of the column. Lateral ties may be against the longitudinal bars or placed in the horizontal bed joint if the requirements of Sec 4.4.6 are met. Spacing of ties shall not be more than 16 times longitudinal bar diameter, 48 times tie bar diameter or the least dimension of the column but not more than 450 mm.
Ties shall be at least 6 mm in diameter for 22 mm diameter or smaller longitudinal bars and 10 mm in diameter for larger longitudinal bars. Ties less than 10 mm in diameter may be used for longitudinal bars larger than 22 mm in diameter, provided the total cross-sectional area of such smaller ties crossing a longitudinal plane is equal to that of the larger ties at their required spacing.
* (c) Anchor Bolt Ties: Additional ties shall be provided around anchor bolts which are set in the top of the column. Such ties shall engage at least four bolts or, alternatively at least four vertical column bars or a combination of bolts and bars totaling four in number. Such ties shall be located within the top 125 mm of the column and shall provide a total of 250 square millimeters or more in cross-sectional area. The upper most ties shall be within 50 mm of the top of the column.
#### 7.6.6.2 Maximum reinforcement size
The maximum size of reinforcing bars shall be 35 mm. Maximum steel area in cell shall be 6 percent of the cell area without splices and 12 percent of cell area with splices.
#### 7.6.6.3 Spacing of longitudinal reinforcement
The clear distance between parallel bars, except in columns, shall not be less than the nominal diameter of the bars or 25 mm, except that bars in a splice may be in contact. This clear distance requirement applies to the clear distance between a contact splice and adjacent splices or bars. The minimum clear distance between parallel bars in columns shall be two and one-half times the bar diameter.
The clear distance between the surface of a bar and any surface of a masonry unit shall not be less than 6 mm for fine grout and 12 mm for coarse grout. Cross webs of hollow units may be used as support for horizontal reinforcement.
All reinforcing bars, except joint reinforcing, shall be completely embedded in mortar or grout and have a minimum cover, including the masonry unit, as specified below:
* (a) 20 mm when not exposed to weather
* (b) 40 mm when exposed to weather
* (c) 50 mm when exposed to soil
#### 7.6.6.4 Anchorage of Flexural Reinforcement
* (a) The tension or compression in any bar at any section must be developed on each side of that section by the required development length. The development length of the bar may be achieved by a combination of an embedment length, anchorage or, for tension only, hooks.
The required development length for deformed bars or deformed wires shall be calculated by:
For bar in tension,
$$
l_d = 0.29d_bf_s \tag{6.7.34}
$$
For bar in compression,
$$
l_d = 0.22d_bf_s \tag{6.7.35}
$$
Development length for plain bars shall be 2.0 times the length calculated by Eq. 6.7.34.
* (b) Except at supports, or at the free end of cantilevers, every reinforcing bar shall be extended beyond the point at which it is no longer needed to resist tensile stress for a distance equal to 12 bar diameters or the depth of the flexural member, whichever is greater. No flexural bars shall be terminated in a tensile zone unless one of the following conditions is satisfied:
* (i) The shear is not over one-half of that permitted, including allowance for shear reinforcement, if any.
* (ii) Additional shear reinforcement in excess of that required is provided each way from the cutoff a distance equal to the depth of the beam. The shear reinforcement spacing shall not exceed d/8rb, where rbis the ratio of the area of bars cutoff to the total area of bars at the section.
* (iii) The continuing bars provide double the area required for flexure at that point or double the perimeter required for reinforcing bond.
* (c) At least one third of the total reinforcement provided for negative moment at the support shall be extended beyond the extreme position of the point of inflection a distance sufficient to develop one half the allowable stress in the bar, one sixteenth of the clear span, or the depth d of the member, whichever is greater.
* (d) Tensile reinforcement of negative moment in any span of a continuous restrained or cantilever beam, or in any member of a rigid frame, shall be adequately anchored by reinforcing bond, hooks or mechanical anchors in or through the supporting member.
* (e) At least one third of the required positive moment reinforcement in simple beams or at the freely supported end of continuous beams shall extend along the same face of the beam into the support at least 150 mm. At least one fourth of the required positive moment reinforcement at the continuous end of continuous beams shall extend along the same face of the beam into the support at least 150 mm.
* (f) Compression reinforcement in flexural members shall be anchored by ties or stirrups not less than 6 mm in diameter, spaced not farther apart than 16 bar diameters or 48 tie diameters whichever is smaller. Such ties or stirrups shall be used throughout the distance where compression steel is required.
* (g) In regions of moment where the design tensile stresses in the steel are greater than 80 percent of the allowable steel tensile stress (Fs), the lap length of splices shall be increased not less than 50 percent of the minimum required length. Other equivalent means of stress transfer to accomplish the same 50 percent increase may be used.
#### 7.6.6.5 Anchorage of shear reinforcement
* (a) Single separate bars used as shear reinforcement shall be anchored at each end by one of the following methods:
* (i) Hooking tightly around the longitudinal reinforcement through 180 degrees.
* (ii) Embedment above or below the mid-depth of the beam on the compression side a distance sufficient to develop the stress in the bar for plane or deformed bars.
* (iii) By a standard hook (see Sec 7.6.6.6) considered as developing 50 N/mm² , plus embedment sufficient to develop the remainder of the stress to which the bars are subject. The effective embedded length shall not be assumed to exceed the distance between the mid-depth of the beam and the tangent of the hook.
* (b) The ends of bars forming single U or multiple U stirrups shall be anchored by one of the methods specified above or shall be bent through an angle of at least 90 degrees tightly around a longitudinal reinforcing bar not less in diameter than the stirrup bar, and shall project beyond the bend at least 12 diameters of the stirrup.
* (c) The loops or closed ends of single U or multiple U stirrups shall be anchored by bending around the longitudinal reinforcement through an angle of at least 90 degrees and project beyond the end of the bend at least 12 diameters of the stirrup.
#### 7.6.6.6 Hooks
* (a) The term "standard hook" shall mean one of the following:
* (i) A 180 degree turn plus an extension of at least 4 bar diameters but not less than 65 mm at the free end of the bar.
* (ii) 90 degree turn plus an extension of at least 12 bar diameters at the free end of the bar.
* (iii) For stirrup and tie anchorage only either a 90 degree or a 135 degree turn, plus an extension of at least 6 bar diameters but not less than 65 mm at the free end of the bar.
* (b) The diameter of bend measured on the inside of the bar other than stirrups and ties, shall not be less than that set forth in Table 6.7.12.
Table 6.7.12: Minimum Diameter of Bend
| Bar Diameter | Minimum Diameter of Bend |
| ------------ | ------------------------ |
| 6 to 25 mm | 6 bar diameters |
| 8 to 35 mm | 8 bar diameters |
* (c) Inside diameter of bend for 12 mm diameter or smaller stirrups and ties shall not be less than 4 bar diameters. Inside diameter of bend for 16 mm diameter or larger stirrups and ties shall not be less than that given in Table 6.7.12.
* (d) Hooks shall not be permitted in the tension portion of any beam, except at the ends of simple or cantilever beams or at the freely supported ends of continuous or restrained beams.
* (e) Hooks shall not be assumed to carry a load which would produce a tensile stress in the bar greater than 50 N/mm² .
* (f) Hooks shall not be considered effective in adding to the compressive resistance of bars.
* (g) Any mechanical device capable of developing the strength of the bar without damage to the masonry may be used in lieu of a hook. Data must be presented to show the adequacy of such devices.
#### 7.6.6.7 Splices
The amount of lap of lapped splices shall be sufficient to transfer the allowable stress of the reinforcement as in Sec 7.6.6.4. In no case shall the length of the lapped splice be less than 30 bar diameters for compression and 40 bar diameters for tension.
Welded or mechanical connections shall develop 125 percent of the specified yield strength of the bar in tension, except for connections of compression bars in columns that are not part of the seismic system and are not subject to flexure, where the compressive strength only need be developed.
When adjacent splices in grouted masonry are separated by 75 mm or less, the lap length shall be increased by 30 percent or the splice may be staggered at least 24 bar diameters with no increase in lap length.
## 7.7 Strength Design of Slender Walls and Shear Walls
### 7.7.1 Design of Slender Walls
In lieu of the procedure set forth in Sec 7.6, the procedures prescribed in this Section, which consider the slenderness of walls by representing effects of axial forces and deflection in calculation of moments, may be used when the vertical load stress at the location of maximum moment computed by Eq. 6.7.36 does not exceed $0.04f_m'$. The value of $f_m'$ shall not exceed 40 N/mm².
$$
\frac{P_w+P_f}{A_g} \leq 0.04f_m' \tag{6.7.36}
$$
Slender masonry walls shall have a minimum nominal thickness of 150 mm.
#### 7.7.1.1 Slender wall design procedure
* (a) Maximum Reinforcement: The reinforcement ratio shall not exceed $0.5\rho_b$, where $\rho_b$ is the balanced steel ratio.
* (b) Moment and Deflection Calculation: All moments and deflections of slender walls shall be calculated based on simple support conditions at top and bottom. For other support and fixity conditions, moments and deflections shall be calculated using established principles of mechanics.
#### 7.7.1.2 Strength design
* (a) Loads: Factored loads shall be determined in accordance with Chapter 2, Loads.
* (b) Required Moment: Required moment and axial force shall be determined at the mid-height of the wall and shall be used for design. The factored moment, Mu, at the mid-height of the wall shall be determined by Eq. 6.7.37.
$$
M_u = \frac{w_uh^2}{8} + P_u\frac{e}{2} + (P_{uw} + P_{uf})\Delta_u \tag{6.7.37}
$$
Where,
* $\Delta_u$ = horizontal deflection at mid-height under factored load; P - Delta effects shall be included in deflection calculation.
* $e$ = eccentricity of $P_u$
* $P_u$ = axial load at mid-height of wall, including tributary wall weight. $= P_{uw} + P_{uf}$
* (c) Design Strength: Design strength in flexure is the nominal moment strength, $M_n$ multiplied by the strength reduction factor, $\phi$ and shall equal or exceed the factored moment, $M_u$.
$$
M_u \leq \phi M_n \tag{6.7.38}
$$
Where,
$M_n$ = nominal moment strength = $A_{se} f_y (d - a/2)$
$A_{se}$ = effective area of steel = $\dfrac{A_sf_y+P_u}{f_y}$
$a$ = depth of stress block due to factored loads = $\dfrac{A_sf_y+P_u}{0.85f_m'b}$
The strength reduction factor $\phi$ for flexure shall be 0.80.
* (d) Design Assumptions: The following are the design assumptions for calculation of nominal strength.
* (i) Nominal strength of singly reinforced masonry wall crosssections subject to combined flexure and axial load shall be based on applicable conditions of equilibrium and compatibility of strains.
* (ii) Strain in reinforcement and masonry walls shall be assumed directly proportional to the distance from the neutral axis.
* (iii) Maximum usable strain at extreme masonry compression fibre shall be assumed equal to 0.003.
* (iv) Stress in reinforcement below specified yield strength shall be taken as times steel strain. For strains greater than that corresponding to stress in reinforcement shall be considered independent of strain and equal to.
* (v) Tensile strength of masonry walls shall be neglected in flexural calculations of strength, except for deflection calculation.
* (vi) Relationship between masonry compressive stress and masonry strain may be assumed to be rectangular as defined by the following:
* Masonry stress of 0.85'\_m\$ shall be assumed uniformly distributed over an equivalent compression zone bounded by edges of the cross-section and a straight line located parallel to the neutral axis at a distance a = 0.85c from the fibre of maximum compressive strain.
* Distance c from fibre of maximum strain to the neutral axis shall be measured in a direction perpendicular to that axis.
#### 7.7.1.3 Deflection calculation
The mid-height deflection, ∆ under service lateral and vertical loads (without load factors) shall be limited to:
The mid-height deflection shall be computed by:
When, $M_{ser} \le M_{cr}$
$$
\Delta_s = \frac{5 M_{ser} h^2}{48 E_m I_g}
$$
When, $M_{cr} < M_{ser} < M_n$
$$
\Delta_s = \frac{5 M_{cr} h^2}{48 E_m I_g} + \frac{5 (M_{ser} - M_{cr}) h^2}{48 E_m I_{cr}}
$$
The cracking moment strength of the wall $M_{cr}$ shall be determined by:
$$
M_{cr} = Sf_r \tag{6.7.42}
$$
The modulus of rupture, $f_r$ shall be determined form Table 6.7.13.
Table 6.7.13: Values of the Modulus of Rupture, $f_r$
| Type of Masonry | Fully Grouted | Partially Grouted |
| ------------------- | ------------------------------------------ | ------------------------------------------ |
| Solid Masonry | 0.17$\sqrt{f'_m}$
$\le 0.65$ N/mm$^2$ | Not allowed |
| Hollow Unit Masonry | 0.33$\sqrt{f'_m}$
$\le 1.2$ N/mm$^2$ | 0.21$\sqrt{f'_m}$
$\le 0.65$ N/mm$^2$ |
### 7.7.2 Design of Shear Walls
Based on ultimate strength design, the procedures described below may be used as an alternative to the procedure specified in Sec 7.6 for the design of reinforced hollow unit masonry shear walls. Provisions for quality control during construction of the shear wall are specified in Sec 7.3.4
#### 7.7.2.1 Required strength
The required strength to resist different combinations of loads shall be determined in accordance with Sec 2.7.3.1 Chapter 2 of this Part.
#### 7.7.2.2 Design strength
Shear walls shall be proportioned such that the design strength exceeds the required strength. Design strength in terms of axial force, shear force and moment provided by the shear wall shall be computed as the nominal strength multiplied by the strength reduction factor $\phi$. Strength reduction factor $\phi$ shall be as follows:
* (a) For axial load and axial load with flexure $\phi$ = 0.65
* (b) For members with $f_y$ less than 410 N/mm$^2$ and with symmetrical reinforcement, $\phi$ may be increased linearly to 0.85 as $\phi P_n$ decreases from $0.10 f'_m A_e$ or $0.25 P_b$ to zero.
For solid grouted walls $P_b$ may be calculated using:
$$
P_b = 0.85f_m'ba_b \tag{6.7.43a}
$$
Where,
$$
a_b = 0.85\left[e_{mu}/\left(e_{mu} + f_y/E_s\right)\right]d \tag{6.7.43b}
$$
* (c) For shear $\phi$ = 0.60. The shear strength reduction factor may be increased to 0.80 for any shear wall when its nominal shear strength exceeds the shear corresponding to development of its nominal flexural strength for the factored load combination.
#### 7.7.2.3 Design Assumptions for Nominal Strength
* (a) Nominal strength of shear wall cross-sections shall be based on assumptions specified in Sec 7.7.1.2(d).
* (b) The maximum usable strain $\varepsilon_{mu}$, at the extreme masonry compression fibre shall not exceed 0.003.
* (c) $f_m'$ shall not be less than 7 N/mm² or greater than 20 N/mm².
#### 7.7.2.4 Axial Strength
The nominal axial strength of shear walls supporting axial loads only shall be calculated by Eq 6.7.44.
$$
P_o = 0.85f_m'(A_e - A_s) + f_yA_s \tag{6.7.44}
$$
The shear wall shall be designed for the axial strength Pu, such that
$$
P_u \leq \phi(0.80)P_o \tag{6.7.45}
$$
#### 7.7.2.5 Shear strength
* (a) The nominal shear strength shall be determined by the provisions as specified in (b) or (c) below. The maximum nominal shear strength values are given in Table 6.7.14.
Table 6.7.14: Maximum Nominal Shear Strength Values
| $M^*/Vd$ | $V_n/(A_e\sqrt{f_m'})$ |
| ----------- | ---------------------- |
| $\leq 0.25$ | 72.0 |
| $\geq 1.00$ | 48.0 |
\* M is the maximum bending moment that occurs simultaneously with the shear load V at the section under consideration. Interpolation may be by straight line for M/Vd values between 0.25 and 1.00.
* (b) The nominal shear strength of shear walls except for shear walls specified in (c) below shall be determined by Eq. 6.7.46.
$$
V_n = V_m + V_s \tag{6.7.46}
$$
Where,
$$
V_m = 0.083C_dA_{mv}\sqrt{f_m'} \tag{6.7.47}
$$
The value of $C_d$ in Eq. 6.7.47 is given as:
$$
C_d = 2.4 \text{ for } \frac{M}{Vd} \leq 0.25 \tag{6.7.48a}
$$
$$
C_d = 1.2 \text{ for } \frac{M}{Vd} \geq 1.0 \tag{6.7.48b}
$$
$$
V_s = A_{mv}\rho_nf_y \tag{6.7.48c}
$$
* (c) For a shear wall whose nominal shear strength exceeds the shear corresponding to development of its nominal flexural strength, two shear regions exist.
* (i) For all cross-sections within the region defined by the base of the shear wall and a plane at a distance $L_w$ above the base of the shear wall, the nominal shear strength shall be determined by Eq. 6.7.49
$$
V_n = A_{mv}\rho_nf_y \tag{6.7.49}
$$
The required shear strength for this region shall be calculated at a distance $\dfrac{L_w}{2}$ above the base of the shear wall but not to exceed one-half storey height.
* (ii) For the other region, the nominal shear strength of the shear wall shall be determined by Eq. 6.7.46.
#### 7.7.2.6 Reinforcement
Reinforcement shall be in accordance with the following:
* (a) Minimum reinforcement shall be provided in accordance with Sec 7.8.5.1 for all seismic areas using this method of analysis.
* (b) When the shear wall failure mode is in flexure, the nominal flexural strength of the shear wall shall be at least 1.8 times the cracking moment strength of a fully grouted wall or 3.0 times the cracking moment strength of a partially grouted wall as obtained from Eq. 6.7.42.
* (c) All continuous reinforcement shall be anchored or spliced in accordance with Sec 7.6.6.4 with $f_s = 0.5f_y$.
* (d) Vertical reinforcement shall not be less than 50 percent of the horizontal reinforcement.
* (e) Spacing of horizontal reinforcement within the region defined in Sec 7.7.2.5(c) shall not exceed three times the nominal wall thickness or 600 mm, whichever is smaller.
#### 7.7.2.7 Boundary member
Boundary members shall be as follows:
* (a) The need for boundary members at boundaries of shear wall shall be determined using the provisions set forth in (b) or (c) below.
* (b) Boundary members shall be provided when the failure mode is flexure and the maximum extreme fibre stress exceeds $0.2f_m'$. The boundary members may be discontinued where the calculated compressive stresses are less than $0.15f_m'$. Stresses may be calculated for the factored forces using a linearly elastic model and gross section properties.
* (c) When the failure mode is flexure, boundary member shall be provided to confine all vertical reinforcement whose corresponding masonry compressive stress exceeds $0.4f_m'$. The minimum length of the boundary member shall be 3 times the thickness of the wall.
* (d) Boundary members shall be confined with minimum of 10 mm diameter bars at a maximum of 200 mm spacing or equivalent within the grouted core and within the region defined by the base of the shear wall and a plane at a distance $L_w$ above the base of the shear wall.
## 7.8 Earthquake Resistant Design
### 7.8.1 General
All masonry structures constructed in the Seismic Zones 2, 3 and 4 shown in Figure 6.2.13 shall be designed in accordance with the provisions of this Section.
### 7.8.2 Loads
Seismic forces on masonry structures shall be determined in accordance with the provisions of Sec 2.5 Chapter 2 of this Part.
### 7.8.3 Materials
* (a) Well burnt clay bricks and concrete hollow blocks having a crushing strength not less than 12 N/mm² shall be used.
* (b) Mortar not leaner than p½ shall be used for masonry constructions.
### 7.8.4 Provisions for Seismic Zone 2 and 3
#### 7.8.4.1 Wall Reinforcement
Vertical reinforcement of at least 12 mm diameter shall be provided continuously from support to support at each corner, at each side of each opening, at the ends of walls and at a maximum spacing of 1.2 m horizontally throughout the wall. Horizontal reinforcement not less than 12 mm diameter shall be provided:
* (a) at the bottom and top of wall openings and shall extend at least 40 bar diameters, with a minimum of 600 mm, past the opening,
* (b) continuously at structurally connected roof and floor levels and at the top of walls,
* (c) at the bottom of the wall or in the top of the foundations when dowelled to the wall,
* (d) at maximum spacing of 3.0 m unless uniformly distributed joint reinforcement is provided. Reinforcement at the top and bottom of openings when continuous in the wall may be used in determining the maximum spacing specified in item (a) above.
#### 7.8.4.2 Stack bond
Where stack bond is used, the minimum horizontal reinforcement ratio shall be $0.0007bt$. This ratio shall be satisfied by uniformly distributed joint reinforcement or by horizontal reinforcement spaced not more than 1.2 m and fully embedded in grout or mortar.
#### 7.8.4.3 Columns
Columns shall be reinforced as specified in Sec 7.6.6.1.
### 7.8.5 Provisions for Seismic Zone 4
All masonry structures built in Seismic Zone 4 shall be designed and constructed in accordance with requirements for Seismic Zone 2 and with the following additional requirements and limitations.
Reinforced hollow unit stack bond construction which is part of the seismic resisting system shall use open-end units so that all head joints are made solid, shall use bond beam units to facilitate the flow of grout and shall be grouted solid.
#### 7.8.5.1 Wall reinforcement
Reinforced masonry walls shall be reinforced with both vertical and horizontal reinforcement. The sum of the areas of horizontal and vertical reinforcement shall be at least 0.002 times the gross cross-sectional area of the wall and the area of reinforcement in either direction shall not be less than 0.0007 times the gross cross-sectional area of the wall. The spacing of reinforcement shall not
exceed 1.20 m. The diameter of reinforcing bar shall not be less than 10 mm except that joint reinforcement may be considered as part of all of the requirements for minimum reinforcement. Reinforcement shall be continuous around wall corners and through intersections. Only reinforcement which is continuous in the wall or element shall be considered in computing the minimum area of reinforcement. Reinforcement with splices conforming to Sec 7.6.6.7 shall be considered as continuous reinforcement.
#### 7.8.5.2 Column reinforcement
The spacing of column ties shall be not more than 225 mm for the full height of columns stressed by tensile or compressive axial overturning forces due to the seismic loads, and 225 mm for the tops and bottoms of all other columns for a distance of one sixth of the clear column height, but not less than 450 mm or maximum column dimension. Tie spacing for the remaining column height shall be not more than 16 bar diameters, 48 tie diameters or the least column dimension, but not more than 450 mm.
#### 7.8.5.3 Stack bond
Where stack bond is used, the minimum horizontal reinforcement ratio shall be $0.0015bt$. If open-end units are used and grouted solid, the minimum horizontal reinforcement ratio shall be $0.0007bt$.
#### 7.8.5.4 Minimum dimension
* (a) Bearing Walls: The nominal thickness of reinforced masonry bearing walls shall be not less than 150 mm except that nominal 100 mm thick load bearing reinforced hollow clay unit masonry walls may be used, provided net area unit strength exceeds 55 N/mm² , units are laid in running bond, bar sizes do not exceed 12 mm with no more than two bars or one splice in a cell, and joints are flush cut, concave or a protruding V section.
* (b) Columns: The least nominal dimension of a reinforced masonry column shall be 375 mm except that if the allowable stresses are reduced to 50 percent of the values given in Sec 7.3, the minimum nominal dimension shall be 250 mm.
#### 7.8.5.5 Shear wall
* (a) When calculating shear or diagonal tension stresses, shear walls which resist seismic forces shall be designed to resist 1.5 times the forces specified in Chapter 2, Loads.
* (b) The portion of the reinforcement required to resist shear shall be uniformly distributed and shall be joint reinforcing, deformed bars, or a combination thereof. The maximum spacing of reinforcement in each direction shall be not less than the smaller of one-half the length or height of the element or more than 1.20 m.
Joint reinforcement used in exterior walls and considered in the determination of the shear strength of the member shall conform to the requirement "Joint Reinforcement for Masonry" (UBC Standard No. 24-15) or "Standard Specification for Steel Wire, Plain, for Concrete Reinforcement", (ASTM, A82).
Reinforcement required to resist in-plane shear shall be terminated with a standard hook or with an extension of proper embedment length beyond the reinforcing at the end of the wall section. The hook or extension may be turned up, down or horizontally. Provisions shall be made not to obstruct grout placement. Wall reinforcement terminating in columns or beams shall be fully anchored into these elements.
* (c) Multi-wythe grouted masonry shear walls shall be designed with consideration of the adhesion bond strength between the grout and masonry units. When bond strengths are not known from previous tests, the bond strength shall be determined by test.
#### 7.8.5.6 Hook
The standard hook for tie anchorage shall have a minimum turn of 135 degrees plus an extension of at least 6 bar diameters, but not less than 100 mm at the free end of the bar. Where the ties are placed in the horizontal bed joints, the hook shall consist of a 90 degree bend having a radius of not less than 4 tie diameters plus an extension of 32 tie diameters.
#### 7.8.5.7 Mortar joints between masonry and concrete
Concrete abutting structural masonry such as at starter courses or at wall intersections not designed as true separation joints shall be roughened to a full amplitude of\` 1.5 mm and shall be bonded to the masonry as per the requirements of this Section as if it were masonry.
### 7.8.6 Additional Requirements
#### 7.8.6.1 Opening in bearing walls
* (a) Tops of all openings in a storey shall preferably be at the same level so that a continuous band could be provided over them, including the lintels throughout the building.
* (b) The total width of the openings shall not be more than half of the length of the walls between the adjacent cross walls, except as provided in (f) below.
* (c) The opening shall preferably be located away from the corner by a clear distance of at least one-eighth of the height of the opening for Seismic Zones 2 and 3, and one-fourth of the height for Seismic Zone 4.
* (d) The horizontal distance between two openings shall not be less than one-fourth of the height of the shorter opening for Seismic Zones 2 and 3, and one-half of the height for Seismic Zone 4.
* (e) The vertical distance between openings one above the other shall be not less than 600 mm.
* (f) Where openings do not comply with the requirements of (b) and (c) above, they shall be strengthened in accordance with Sec 7.8.6.5.
* (g) If a window or ventilator is to be projected out, the projection shall be in reinforced masonry or concrete and well anchored.
* (h) If the height of an opening is approximately full height of a wall, dividing the wall into two portions, these portions of the wall shall be reinforced with horizontal reinforcement of 6 mm diameter bars at not more than 600 mm intervals, one on inner and one on outer face, properly tied to vertical steel at jambs and corners or junctions of walls where used.
* (i) The use of arches to span over the openings is a source of weakness and shall be avoided unless steel ties are provided.
#### 7.8.6.2 Strengthening arrangements
All masonry buildings shall be strengthened by the methods specified in Table 6.7.15.
Table 6.7.15: Strengthening of Masonry Buildings for Earthquake
| Seismic | No. of | Strengthening Arrangements to be Provided. |
| ------- | ---------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Zones | Storey | |
| 1 | Up to 4 | a) Masonry mortar shall not be leaner than p½ |
| 2, 3 | Up to 2
with
pitched
roof | a) Masonry mortar shall not be leaner than p½
b) By lintel and roof band (Sec 7.8.6.3)
c) By vertical reinforcement at corners and junctions of
walls (Sec 7.8.6.4)
d) Bracing in plan at tie level for pitched roof\* |
| | 3 to 4 | a) Masonry mortar shall not be leaner than p½
b) By lintel and roof band (Sec 7.8.6.3)
c) By vertical reinforcement at corners and junctions of
walls (Sec 7.8.6.4) |
| | | d) Vertical
reinforcement
at
jambs
of
openings
(Sec 7.8.6.5) |
| | | e) Bracing in plan at tie level for pitched roof\* |
| Zones | Storey | |
| 4 | Up to 4 | a) Masonry mortar shall not be leaner than p½ |
| | | b) By lintel and roof band (Sec 7.8.6.3) |
| | | c) By vertical reinforcement at corners and junctions of
walls (Sec 7.8.6.4) |
| | | d) Vertical
reinforcement
at
jambs
of
openings
(Sec 7.8.6.5) |
| | | e) Bracing in plan at tie level for pitched roof\* |
* At tie level all the trusses and the gable end shall be provided with diagonal bracing in plan so as to transmit the lateral shear due to earthquake force to the gable walls acting as shear walls at the ends.
#### 7.8.6.3 Bands
Roof band need not be provided underneath reinforced concrete or brickwork slabs resting on bearing walls, provided that the slabs are continuous over parts between crumple sections, if any, and cover the width of end walls fully.
The band shall be made of reinforced concrete with rnot less than 20 N/mm2 or reinforced brickwork in cement mortar not leaner than 1: 4. The bands shall be to the full width of the wall and not less than 75 mm in depth and shall be reinforced as indicated in Table 6.7.16. In case of reinforced brickwork, the thickness of joints containing steel bars shall be increased so as to have a minimum mortar cover of 6 mm around the bar. In bands of reinforced brickwork, the area of steel provided shall be equal to that specified above for reinforced concrete bands.
Table 6.7.16: Band Reinforcement
| Seismic |
Plain Mild Steel Bars | High Strength | Links |
| ------- | --------------------------- | --------------------- | ---------------- |
| Zones | | Deformed Bars | |
| 2, 3 | 2 - 12 mm dia, one on | 2 - 10 mm dia, one on | 6 mm dia, 150 mm |
| | each face of the wall with | each face of the wall | c/c |
| | suitable cover | with suitable cover | |
| 4 | 2 - 16 mm dia, one on | 2 - 12 mm dia, one on | 6 mm dia, 150 mm |
| | each face of the wall with | each face of the wall | c/c |
| | suitable cover | with suitable cover | |
#### 7.8.6.4 Strengthening of corner and junctions
Vertical steel at corners and junctions of walls which are up to one and a half bricks thick shall be provided either with mild steel or high strength deformed bars as specified in Table 6.7.17. For thicker walls, reinforcement shall be increased proportionately. The reinforcement shall be properly embedded in the plinth masonry of foundations and roof slab or roof band so as to develop its tensile strength in bond and passing through the lintel bands in all storeys. Bars in different storeys may be welded or suitably lapped.
* (a) Typical details of vertical steel in brickwork and hollow block at corners, T-junctions and jambs of opening are shown in Figures 6.7.1 and 6.7.2.
* (b) Details of vertical reinforcement given in Table 6.7.17 are applicable to brick masonry and hollow block masonry.
#### 7.8.6.5 Strengthening of jambs of openings
Openings in bearing walls shall be strengthened, where necessary, by providing reinforced concrete members or reinforcing the brickwork around them as shown in Figure 6.7.3.
#### 7.8.6.6 Walls adjoining structural framing
Where walls are dependent on the structural frame for lateral support they shall be anchored to the structural members with metal ties or keyed to the structural members. Horizontal ties shall consist of 6 mm diameter U-bars spaced at a maximum of 450 mm on centre and embedded at least 250 mm into the masonry and properly tied to the vertical steel of the same member.
Table 6.7.17: Vertical Reinforcement for Brick and Hollow Block Masonry
| No. of
Storeys | Storeys | Diameter of Single Bar or
Equivalent Area of Plain Mild
Steel Bar to be Provided
(mm) | Diameter of Single Bar or
Equivalent Area of High Strength
Deformed Bar to be Provided
(mm) |
| ------------------- | ------- | ---------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------- |
| | | Zone 2 and 3
Zone 4 | Zone 2 and 3
Zone 4 |
| 1 | - | nil
12 | nil
10 |
| 2 | Top | nil
12 | nil
10 |
| | Bottom | nil
16 | nil
12 |
| 3 | Top | 12
12 | 10
10 |
| | Middle | 12
16 | 10
12 |
| | Bottom | 16
16 | 12
12 |
| 4 | Top | 12
12 | 10
10 |
| | Third | 12
16 | 10
12 |
| | Second | 16
20 | 12
16 |
| | Bottom | 16
25 | 12
20 |
![Typical details of vertical reinforcement in brick masonry showing corner, T-junction, jamb, and lintel band details]()
![Typical details of vertical reinforcement in hollow block masonry showing opening and corner reinforcement layouts]()
![Minimum reinforcement in walls and around openings in Seismic Zones 2, 3 and 4 showing lintel band, floor band, and jamb bars]()
## 7.9 Provisions For High Wind Regions
### 7.9.1 General
The provisions of this Section shall apply to masonry structures located at regions where the basic wind speed is greater than 200 km/h.
### 7.9.2 Materials
Materials for masonry structures shall generally comply with the provisions of Part 5; however, there are some special requirements for masonry construction in high wind regions, which are given below:
* (a) Burnt clay bricks shall have a compressive strength not less than 15 N/mm² ,
* (b) Grout shall have a minimum compressive strength of 12.5 N/mm² ,
* (c)Mortar for exterior walls and interior shear walls shall be type M 1or M 2,
* (d) Unburnt clay masonry units shall not be used.
### 7.9.3 Construction Requirements
Masonry construction shall comply with the provisions of Sec 7.10.
### 7.9.4 Foundation
Footings shall have a thickness of not less than 375 mm and shall be extended 450 mm below the undisturbed ground surface. Foundation stem wall shall have the same width and reinforcement as the wall it supports.
### 7.9.5 Drainage
Walls retaining more than 1 m of earth and enclosing interior spaces or floors below grade shall have minimum 100 mm diameter footing drain. A slope of 1:50 away from the building shall be provided around the building.
### 7.9.6 Wall Construction
#### 7.9.6.1
Minimum thickness of different types of wall shall be as given in Table 6.7.18.
#### 7.9.6.2
All walls shall be laterally supported at the top and bottom. The maximum unsupported height of bearing walls or other masonry walls shall be 3.5 m. Gable end walls may be 4.5 m high at their peak.
#### 7.9.6.3
The span of lintels over openings shall not exceed 3.5 m. All lintels shall be reinforced and the reinforcement bars shall extend not less than 600 mm beyond the edge of opening and into lintel supports.
#### 7.9.6.4
Walls shall be adequately reinforced.
#### 7.9.6.5
Anchors between walls and floors or roofs shall be embedded in grouted cells or cavities and shall conform to Sec 7.9.7 below.
Table 6.7.18: Minimum thickness of Walls in High Wind Region
| Type of Wall | Minimum Thickness (mm) |
| ------------------------------------------ | ---------------------- |
| Unreinforced grouted brick wall | 250 |
| Reinforced exterior bearing wall | 200 |
| Unreinforced hollow and solid masonry wall | 200 |
| Interior nonbearing wall | 150 |
### 7.9.7 Floor and Roof Systems
Floors and roofs of all masonry structures shall be adequately anchored with the wall it supports to resist lateral and uplift forces due to wind specified in Sec 2.4 of this Part.
### 7.9.8 Lateral Force Resistance
#### 7.9.8.1
Strapping, approved framing anchors and mechanical fasteners, bond beams and vertical reinforcement shall be installed to provide a continuous tie from the roof to foundation system as shown in Figure 6.7.4. In addition, roof and floor systems, masonry shear walls, or masonry or wood cross walls shall be provided for lateral stability.
#### 7.9.8.2
Floor and roof diaphragms shall be properly connected to masonry walls. Gable and sloped roof members not supported at the ridge shall be tied by the ceiling joist or equivalent lateral ties located as close to where the roof members bear on the wall as practically possible and not at more than 1.2 m on centers. Collar ties shall not be used for these lateral ties.
#### 7.9.8.3
Masonry walls shall be provided around all sides of floor and roof systems in accordance with Figure 6.7.5. The cumulative length of exterior masonry walls along each side of the floor or roof systems shall be at least 20 percent of the parallel dimension. Required elements shall be without openings and shall not be less that 1.25 m in width.
Interior cross walls at right angles to bearing walls shall be provided when the length of the building perpendicular to the span of the floor of roof framing exceeds twice the distance between shear walls or 10 m, whichever is greater.
#### 7.9.8.4
When required interior cross wall shall be at least 1.8 m long and reinforced with 2 mm wire joint reinforcement spaced not more than 400 mm on centre.
![Continuous tie from roof to foundation of masonry structure showing roof truss connection, bond beam, vertical reinforcement, and foundation tie]()
![Masonry walls required in high wind regions showing minimum wall length and opening restrictions]()
## 7.10 Construction
### 7.10.1 General
Masonry shall be constructed according to the provisions of this Section.
### 7.10.2 Storage and Preparation of Construction Materials
Storage, handling and preparation at the site shall conform to the following:
* (a) Masonry materials shall be stored in such a way that at the time of use the materials are clean and structurally suitable for the intended use.
* (b) All metal reinforcement shall be free from loose rust and other coatings that inhibit reinforcing bond.
* (c) Burnt clay units shall have a rate of absorption per minute not exceeding 1 litre/m2 at the time of lying. In the absorption test the surface of the unit shall be held 3 mm below the surface of the water.
* (d) Burnt clay units shall be thoroughly wetted before placing. Concrete masonry units shall not be wetted unless otherwise approved.
* (e) Materials shall be stored in such a manner that deterioration or intrusion of foreign materials is prevented and at the time of mixing the material conforms to the applicable requirements.
* (f) The method of measuring materials for mortar and grout shall be such that proportions of the materials can be easily controlled.
* (g) Mortar or grout mixed at the job site shall be mixed for a period of time not less than 3 minutes or more than 10 minutes in a mechanical mixer with the amount of water required to provide the desired workability. Hand mixing of small amounts of mortar is permitted. Mortar may be retempered. Mortar or grout which has hardened or stiffened due to hydration of the cement shall not be used, but under no case shall mortar be used two and one-half hours, nor grout used one and one-half hours, after the initial mixing water has been added to the dry ingredients at the job site.
### 7.10.3 Placing Masonry Units
* (a) The mortar shall be sufficiently plastic and units shall be placed with sufficient pressure to extrude mortar from the joint and produce a tight joint. Deep furrowing which produces voids shall not be used.
The initial bed joint thickness shall not be less than 5 mm or more than 25 mm; subsequent bed joints shall be not less than 5 mm or more than 15 mm in thickness.
* (b) All surfaces in contact with mortar or grout shall be clean and free of deleterious materials.
* (c) Solid masonry units shall have full head and bed joints.
* (d) All head and bed joints shall be filled solidly with mortar for a distance from the face of the unit not less than the thickness of the shell. Head joints of open-end units with beveled ends need not be mortared. The beveled ends shall form a grout key which permits grout within 16 mm of the face of the unit. The units shall be tightly butted to prevent leakage of grout.
### 7.10.4 Verticality and Alignment
All masonry shall be built true and plumb within the tolerances prescribed below. Care shall be taken to keep the perpends properly aligned.
* (a) Deviation from vertical within a storey shall not exceed 6 mm per 3m height.
* (b) Deviation in verticality in total height of any wall of a building more than one storey in height shall not exceed 12 mm.
* (c) Deviation from position shown on plan of any brickwork shall not exceed 12 mm.
* (d) Relative displacement between load bearing walls in adjacent storeys intended to be in vertical alignment shall not exceed 6 mm.
* (e) Deviation of bed joint from horizontal in a length of 12 m shall not exceed 6 mm subject to a maximum deviation of 12 mm.
* (f) Deviation from the specified thickness of bed joints, cross joints and perpends shall not exceed one-fifth of the specified thickness.
### 7.10.5 Reinforcement Placing
Reinforcing details shall conform to the requirements of Sec 7.6.6. Metal reinforcement shall be located in accordance with the plans and specifications. Reinforcement shall be secured against displacement prior to grouting by wire positioners or other suitable devices at intervals not exceeding 20 bar diameters.
Tolerances for the placement of steel in walls and flexural elements shall be ±12 mm for 0 ≤200 mm, ±25 mm for 200 mm ≤0 ≤600 mm and ± 30 mm for 0 > 600 mm. Tolerance for longitudinal location of reinforcement shall be ± 50 mm.
### 7.10.6 Grouted Masonry
Grouted masonry shall be constructed in such a manner that all elements act together as a structural element.
Space to be filled with grout shall be clean and shall not contain any foreign materials. Grout materials and water content shall be controlled to provide adequate workability and shall be mixed thoroughly. The grouting of any section of wall shall be completed in one day with no interruptions greater than one hour.
Size and height limitations of the grout space or cell shall not be less than those shown in Table 6.7.19. Higher grout pours or smaller cavity widths or cell size than shown in Table 6.7.19 may be used when approved, if it can be demonstrated that grout spaces are properly filled.
Cleanouts are required for all grout pours over 1.5 m in height. When required, cleanouts shall be provided in the bottom course at every vertical bar but shall not be spaced more than 800 mm on centre for solidly grouted masonry. When cleanouts are required, they shall be sealed after inspection and before grouting. When cleanouts are not provided, special provisions must be made to keep the bottom and sides of the grout spaces, as well as the minimum total clear area as required by Table 6.7.19, clean and clear prior to grouting.
Table 6.7.19: Grouting Limitations
| Grout | Grout pour
Maximum | Minimum Dimensio
within Grou | ns of the Total Clear Areas
t Spaces and Cells |
| ----- | ----------------------- | --------------------------------- | --------------------------------------------------- |
| Type | Height (m) | Multi-wythe
Masonry (mm) | Hollow Unit
Masonry (mm) |
| | 0.30 | 20 | 40×50 |
| | 1.50 | 40 | 40×50 |
| Fine | 2.40 | 40 | 40×75 |
| | 3.65 | 40 | 45×75 |
| | 7.30 | 50 | 75×75 |
| | 0.30 | 40 | 40×75 |
| C | 1.50 | 50 | 60×75 |
| oarse | 2.40 | 50 | 75×75 |
| | 3.65 | 60 | 75×75 |
| | 7.30 | 75 | 75×100 |
### 7.10.7 Chases, Recesses and Holes
* (a) Chases, recesses and holes may be permitted in masonry provided either they are considered in the structural design or they are not cut into walls made of hollow or perforated units, or vertical chases are planned instead of horizontal chases.
* (b) Depth of vertical and horizontal chases in load bearing walls shall not exceed one-third and one-sixth of the wall thickness respectively.
* (c) Vertical chases shall not be closer than 2 m in any stretch of wall and shall not be located within 350 mm of an opening or within 230 mm of a cross wall that serves as stiffening wall for stability. Width of a vertical chase shall not exceed the thickness of wall in which it occurs.
* (d) Horizontal chases shall be located in the upper or lower middle third height of wall at a distance not less than 600 mm from lateral support. No horizontal chase shall exceed one metre in length and there shall not be more than 2 chases in any one wall. Horizontal chases shall have minimum mutual separation distance of 500 mm. Sum of lengths of all chases and recesses in any horizontal plane shall not exceed one-fourth the length of the wall.
* (e) Lintel shall not be used to support masonry directly above a recess or a hole wider than 300 mm. No lintel however, is necessary in case of a circular recess or hole exceeding 300 mm in diameter provided upper half of the recess or hole is built as a semi-circular arch of adequate thickness and there is adequate length of masonry on the sides of openings to resist the horizontal thrust.
* (f) Recesses and holes in masonry shall be kept at the time of construction so as to avoid subsequent cutting. If cutting is necessary, it shall be done using sharp tools without causing heavy impact and damage to the surrounding areas.
* (g) No chase, recess or hole shall be provided in half-brick load bearing wall, excepting the minimum number of holes needed for scaffolding.
## 7.11 Confined Masonry
### 7.11.1 General
Confined masonry construction consists of masonry walls (made either of clay brick or concrete block units) and horizontal and vertical RC confining members built on all four sides of a masonry wall panel. Vertical members, called tiecolumns or practical columns, resemble columns in RC frame construction except that they tend to be of far smaller cross-section. Horizontal elements, called tie-beams, resemble beams in RC frame construction. To emphasize that confining elements are not beams and columns, alternative terms horizontal ties and vertical ties could be used instead of tie-beams and tie-columns.
The confining members are effective in
* (a) Enhancing the stability and integrity of masonry walls for in-plane and out-of-plane earthquake loads (confining members can effectively contain damaged masonry walls),
* (b) Enhancing the strength (resistance) of masonry walls under lateral earthquake loads, and
* (c) Reducing the brittleness of masonry walls under earthquake loads and hence improving their earthquake performance.
The structural components of a confined masonry building are (see Figure 6.7.6):
* (a) Masonry walls – transmit the gravity load from the slab(s) above down to the foundation. The walls act as bracing panels, which resist horizontal earthquake forces. The walls must be confined by concrete tie-beams and tie-columns to ensure satisfactory earthquake performance.
* (b) Confining elements (tie-columns and tie-beams) - provide restraint to masonry walls and protect them from complete disintegration even in major earthquakes.
These elements resist gravity loads and have important role in ensuring vertical stability of a building in an earthquake.
* (a) Floor and roof slabs - transmit both gravity and lateral loads to the walls. In an earthquake, slabs behave like horizontal beams and are called diaphragms.
* (b) Plinth band - transmits the load from the walls down to the foundation. It also protects the ground floor walls from excessive settlement in soft soil conditions.
* (c) Foundation - transmits the loads from the structure to the ground.
The design of confined masonry members shall be based on similar assumptions to those set out for unreinforced and for reinforced masonry members. Confined masonry shall be constructed according to the provisions of this Section.
![Isometric diagram of a typical confined masonry building showing masonry walls, tie-columns, tie-beams, and plinth band]()
### 7.11.2 Difference of Confined Masonry from RC Frame Construction
The appearance of a finished confined masonry construction and a RC frame construction with masonry in fills may look alike, however these two construction systems are substantially different. The main differences are related to the construction sequence, as well as to the manner in which these structures resist gravity and lateral loads. These differences are summarized in Table 6.7.20 and are illustrated by diagrams in Figure 6.7.7.
In confined masonry construction, confining elements are not designed to act as a moment-resisting frame; as a result, detailing of reinforcement is simple. In general, confining elements have smaller cross-sectional dimensions than the corresponding beams and columns in a RC frame building. It should be noted that the most important difference between the confined masonry walls and infill walls is that infill walls are not load-bearing walls, while the walls in a confined masonry building are.
A transition from RC frame to confined masonry construction in most cases leads to savings related to concrete cost, since confining elements are smaller in size than the corresponding RC frame members.
Table 6.7.20: Comparison between confined masonry and RC frame construction
| Component | Confined masonry construction | RC frame construction |
| --------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Gravity and
lateral load-
resisting
system | Masonry walls are the main load
bearing elements and are expected
to resist both gravity and lateral
loads. Confining elements (tie-
beams
and
tie-columns)
are
significantly smaller in size than
RC beams and columns. | RC frames resist both gravity
and lateral loads through
their relatively large beams,
columns,
and
their
connections. Masonry in fills
are not load-bearing walls. |
| Foundation
construction | Strip footing beneath the wall and
the RC plinth band | Isolated footing beneath each
column |
| Superstructure
construction
sequence | 1. Masonry walls are constructed
first.
2. Subsequently, tie-columns are
cast in place.
3. Finally,
tie-beams
are
constructed on top of the walls,
simultaneously
with
the
floor/roof slab construction. | 1. The frame is constructed
first.
2. Masonry
walls
are
constructed at a later stage
and are not bonded to the
frame
members;
these
walls are nonstructural,
that is, non-load bearing
walls. |
### 7.11.3 Mechanism of Resisting Earthquake Effects
A confined masonry building subjected to earthquake ground shaking can be modeled as a vertical truss, as shown in Figure 6.7.8. Masonry walls act as diagonal struts subjected to compression, while reinforced concrete confining members act in tension and/or compression, depending on the direction of lateral earthquake forces. This model is appropriate before the cracking in the walls takes place. Subsequently, the cracking is concentrated at the ground floor level and significant lateral deformations take place. Under severe earthquake ground shaking, the collapse of confined masonry buildings may take place due to soft storey effect similar to the one observed in RC frames with masonry in fills, as shown in Figure 6.7.8. The following failure modes are characteristic of confined masonry walls:
(a) Shear failure mode, and; (b) Flexural failure mode.
Note that, in confined masonry structures, shear failure mode develops due to in-plane seismic loads (acting along in the plane of the wall), whereas flexural failure mode may develop either due to in-plane or out-of-plane loads (acting perpendicular to the wall plane).
Shear failure mode is characterized by distributed diagonal cracking in the wall. These cracks propagate into the tie-columns at higher load levels, as shown in Figure 6.7.9. Initially, a masonry wall panel resists the effects of lateral earthquake loads by itself while the confining elements (tie-columns) do not play a significant role. However, once the cracking takes place, the wall pushes the tie-columns sideways. At that stage, vertical reinforcement in tie-columns becomes engaged in resisting tension and compression stresses. Damage in the tie-columns at the ultimate load level is concentrated at the top and the bottom of the panel. These locations, characterized by extensive crushing of concrete and yielding of steel reinforcement, are called plastic hinges (Figure 6.7.10). Note that the term plastic hinge has a different meaning in the context of confined masonry components than that referred to in relation to RC beams and columns, where these hinges form due to flexure and axial loads. In confined masonry construction, tie-beams and tie-columns resist axial loads. Shear failure can lead to severe damage in the masonry wall and the top and bottom of the tie-columns.
![Comparison between RC frame construction and confined masonry construction showing load paths and strip footing]()
![Confined masonry building seismic behavior: (a) vertical truss model with diagonal struts; (b) soft storey collapse at ground floor level]()
![Shear failure mode in confined masonry walls showing diagonal cracking propagating into tie-columns]()
![Plastic hinge formation at the top and bottom of tie-columns in a confined masonry wall under shear failure]()
Flexural failure caused by in-plane lateral loads is characterized by horizontal cracking in the mortar bed joints on the tension side of the wall, as shown in Figure 6.7.11. Extensive horizontal cracking, which usually takes place in tiecolumns, as well as shear cracking can be observed.
Irrespective of the failure mechanism, tie-columns resist the major portion of gravity load when masonry walls suffer severe damage (this is due to their high axial stiffness and load resistance). The failure of a tie- column usually takes place when cracks propagate from the masonry wall into the tie-column and shear it off. Subsequently, the vertical stability of the entire wall is compromised. Vertical strains in the confined masonry walls decrease at an increased damage level, thereby indicating that a major portion of the gravity load is resisted by tie-columns. This finding confirms the notion that tiecolumns have a critical role in resisting the gravity load in damaged confined masonry buildings and ensuring their vertical stability.
### 7.11.4 Key Factors Influencing Seismic Resistance
#### 7.11.4.1 Wall density
Wall density is believed to be one of the key parameters influencing the seismic performance of confined masonry buildings. It can be determined as the transverse area of walls in each principal direction divided by the total floor area of the building.
#### 7.11.4.2 Masonry units and mortar
The lateral load resistance of confined masonry walls strongly depends on the strength of the masonry units and the mortar used. The walls built using lowstrength bricks or ungrouted hollow block units had the lowest strength while the ones built using grouted or solid units had the largest strength. However, the use of grouted and solid units results in an increase both in wall mass and seismic loads. Also, the weaker the mortar the lower the masonry strength (due to the unit-mortar interaction, the masonry strength is always lower than the unit strength). There is no significant difference in strength between unreinforced and confined masonry wall specimens with the same geometry and material properties.
#### 7.11.4.3 Tie-columns
Tie-columns significantly influence the ductility and stability of cracked confined masonry walls. The provision of closely spaced transverse reinforcement (ties) at the top and bottom ends of tie-columns results in improved wall stability and ductility in the post-cracking stage.
#### 7.11.4.4 Horizontal wall reinforcement
Horizontal reinforcement has a beneficial effect on wall ductility. Specimens with horizontal reinforcement showed a more uniform distribution of inclined shear cracks than the unreinforced specimens. Horizontal rebars should be anchored into the tie-columns; the anchorage should be provided with 900 hooks at the far end of the tie-column (Figure 6.7.12). The hooks should be embedded in the concrete within the tie-column (note that the tie-column reinforcement was omitted from the figure). The bar diameter should be larger than 3.5 mm and less than ¾ the joint thickness.
#### 7.11.4.5 Openings
When the opening area is less than approximately 10 percent of the total wall area, the wall lateral load resistance is not significantly reduced as compared to a solid wall (i.e. wall without openings). The walls with larger openings develop diagonal cracks (same as solid walls), except that the cracks are formed in the piers between the openings; thus, diagonal struts form in the piers, as shown in Figure 6.7.13.
### 7.11.5 Verification of Members
#### 7.11.5.1
In the verification of confined masonry members subjected to bending and/or axial loading, the assumptions for reinforced masonry members should be adopted. In determining the design value of the moment of resistance of a section a rectangular stress distribution may be assumed, based on the strength of the masonry, only. Reinforcement in compression should also be ignored.
#### 7.11.5.2
In the verification of confined masonry members subjected to shear loading the shear resistance of the member should be taken as the sum of the shear resistance of the masonry and of the concrete of the confining elements. In calculating the shear resistance of the masonry the rules for unreinforced masonry walls subjected to shear loading should be used, considering the length of the masonry element. Reinforcement of confining elements should not be taken into account.
#### 7.11.5.3
In the verification of confined masonry members subjected to lateral loading, the assumptions set out for unreinforced and reinforced masonry walls should be used. The contribution of the reinforcement of the confining elements should be considered.
![Flexural failure mode of confined masonry walls showing horizontal cracking in mortar bed joints on tension side]()
![Horizontal reinforcement in confined masonry walls with 90 degree hook anchorage into tie-columns]()
![Failure modes in confined masonry walls with openings showing diagonal cracks and struts formed in piers]()
### 7.11.6 Confined Masonry Members
#### 7.11.6.1
Confined masonry members shall not exhibit flexural cracking nor deflect excessively under serviceability loading conditions.
#### 7.11.6.2
The verification of confined masonry members at the serviceability limit states shall be based on the assumptions given for unreinforced masonry members.
### 7.11.7 Architectural Guideline
#### 7.11.7.1 Building Layout
* (a) The building should not be excessively long relative to its width; ideally, the length-to-width ratio should not exceed 4.
* (b) The walls should be continuous up the building height.
* (c) Openings (doors and windows) should be placed in the same position up the building height.
#### 7.11.7.2 Walls
* (a) At least two fully confined walls should be provided in each direction.
* (b) For Seismic Zone 1 and 2, wall density of at least 2 percent in each of two orthogonal directions is required to ensure good earthquake performance of confined masonry construction. The wall density for Seismic Zones 3 and 4 should be at least 4 percent and 5 percent respectively. Wall density can be defined as the total cross sectional area of all walls in one direction divided by the sum of the floor plan areas for all floors in a building.
#### 7.11.7.3 Building Height
Confined masonry is suitable for low- to medium-rise building construction. Confined masonry buildings will be subject to the following height restrictions:
* (a) Up to 4-storey high for Seismic Zone 1 and 2
* (b) Up to 3-storey high for Seismic Zone 3
* (c) Up to 2-storey high for Seismic Zone 4
### 7.11.8 Confined Masonry Details
#### 7.11.8.1
Confined masonry walls shall be provided with vertical and horizontal reinforced concrete or reinforced masonry confining elements so that they act together as a single structural member.
#### 7.11.8.2
Top and sides confining elements shall be cast after the masonry has been built so that they will be duly anchored together.
#### 7.11.8.3
Vertical confining elements should be placed:
* (a) at the free edges of each structural wall element;
* (b) at both sides of any wall opening with an area of more than 1.5 m2 ;
* (c) within the wall if necessary in order not to exceed a spacing of 5 m between the confining elements;
* (d) at the intersections of structural walls, wherever the confining elements imposed by the above rules are at a distance larger than 1.5 m.
#### 7.11.8.4
Horizontal confining elements shall be placed in the plane of the wall at every floor level and in any case with a vertical spacing of not more than 4 m.
#### 7.11.8.5
Confining elements should have a cross-sectional area not less than 0.02 m2 , with a minimum dimension of 150 mm in the plan of the wall. In double-leaf walls the thickness of confining elements should assure the connection of the two leaves and their effective confinement.
#### 7.11.8.6
The longitudinal reinforcement of confining elements may not have a cross-sectional area less than 300 mm2 , nor than 1 percent of the cross-sectional area of the confining element. The detailing of the reinforcements should be in accordance with Chapter 8.
#### 7.11.8.7
Stirrups not less than 6 mm in diameter and spaced not more than 300 mm should be provided around the longitudinal reinforcement. Column ties should preferably have 135° hooks – the use of 90° hooks is not recommended. At a minimum, 6 mm ties at 200 mm spacing (6 mm\@200 mm) should be provided. It is recommended to use 6 mm ties at 100 mm spacing (6 mm\@100 mm) in the column end-zones (top and bottom).
#### 7.11.8.8
To ensure the effectiveness of tie-beams in resisting earthquake loads, longitudinal bars should have a 90° hooked anchorage at intersections, as shown in Figure 6.7.14. The hook length should be at least 500 mm.
#### 7.11.8.9
Proper detailing of the tie-beam-to-tie-column connections is a must for satisfactory earthquake performance of the entire building. Reinforcing bars must be properly anchored. A typical connection detail at the roof level is shown in Figure 6.7.15. Note that the tie-column reinforcement needs to be extended into the tie-beam as much as possible, preferably up to the underside of the top tie-beam reinforcement. A hooked anchorage needs to be provided (90° hooks) both for the tie-column and tie-beam reinforcement.
#### 7.11.8.10
Special lintel beams may be required across larger openings having a width exceeding 1.5 m. Additional reinforcement bars need to be provided. Lintel beams can be integrated with the tie-beams at the floor level.
#### 7.11.8.11
Lap splices may not be less than 60 bar diameters or 500 mm in length. Splicing should take place at column mid height, except for the ground floor level (where splicing is not permitted).
#### 7.11.8.12
The minimum wall thickness should not be less than 100 mm. The wall height/thickness ratio should not exceed 30.
#### 7.11.8.13
Toothed edges should be left on each side of the wall, as shown in Figure 6.7.16(a). Toothed edges are essential for adequate wall confinement, which contributes to satisfactory earthquake performance. Alternatively, when the interface between the masonry wall and the concrete tie-column needs to remain smooth for appearance’s sake, steel dowels should be provided in mortar bed joints to ensure interaction between the masonry and the concrete during an earthquake, Figure 6.7.16(b).
#### 7.11.8.14
Concrete in the tie-columns can be poured once the desired wall height has been reached. The masonry walls provide formwork for the tiecolumns on two sides; however the formwork must be placed on the remaining two sides.
### 7.11.9 Foundation and Plinth Construction
The foundation should be constructed as in traditional brick masonry construction. Either an uncoursed random rubble stone masonry footing or a RC strip footing can be used. A RC plinth band should be constructed on top of the foundation. In confined masonry construction, plinth band is essential for preventing building settlements in soft soil areas. An alternative foundation solution with RC strip footing is also illustrated in Figure 6.7.17.
![Tie-beam construction: (a) wall intersections; (b) 90 degree hooked anchorage to longitudinal reinforcement]()
![Detailing requirements for tie-beam to tie-column connection at roof level with hooked anchorage]()
![Confined masonry wall-column interface: (a) toothed wall construction; (b) horizontal dowels in mortar bed joints]()
![Foundation construction for confined masonry: (a) RC plinth band and stone masonry foundation; (b) RC strip footing]()
# Chapter 8: Detailing of Reinforcement in Concrete Structures
Source: https://docs.sayed.app/bnbc/part-6-structural-design/chapter-8-detailing-of-reinforcement-in-concrete-structures
## 8.1 Introduction
Provisions of Sections 8.1 and 8.2 of Chapter 8 shall apply for detailing of reinforcement in reinforced concrete members, in general. For reinforced concrete structures, subject to earthquake loadings in seismic design categories B, C and D, special provisions contained in Sec 8.3 of this Chapter shall apply. The definitions and notation provided in the following Sections are related to Sec 8.3. The definitions and notation used in other Sections, unless otherwise mentioned, are similar to those provided in Sections 6.1.1 and 6.1.2 Chapter 6.
### 8.1.1 Definitions and Notation
#### 8.1.1.1 Definitions
BASE OF The level at which earthquake motions are assumed to STRUCTURE be imparted to a structure. This level does not necessarily coincide with the ground level. BOUNDARY Members along wall and diaphragm edges MEMBERS strengthened by longitudinal and transverse reinforcement. These members do not necessarily require an increase in the thickness of the wall or diaphragm. If required, edges of openings within walls and diaphragms shall be provided with boundary members. COLLECTOR Elements that are used to transmit the inertial forces ELEMENTS within the diaphragms to members of the lateral force resisting systems. CROSS TIE A continuous bar having a hook not less than 135o with at least a six diameter extension at one end but not less than 75 mm, and a hook not less than 90o with at least a six diameter extension at the other end. The hooks shall engage peripheral longitudinal bars. The 90o hooks of two successive cross ties engaging the same longitudinal bars shall be alternated end for end.
| DEVELOPMENT
LENGTH OF A
STANDARD HOOK | The shortest distance between the critical section and
a tangent to the outer edge of the 90o hook. |
| ----------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| HOOP | A hoop is a closed tie or continuously round tie. A
closed tie can be made up of several reinforcing
elements with 135ohooks having a six diameter
extension at each end (but not less than 75 mm). A
continuously round tie shall have at each end a 135o
hook with a six diameter extension that engages the
longitudinal reinforcement but not less than 75 mm. |
| LATERAL FORCE
RESISTING SYSTEM | That portion of the structure composed of members
designed to resist forces related to earthquake effects. |
| SHELL CONCRETE | Concrete
outside
the
transverse
reinforcement
confining the concrete |
| STRUCTURAL | Structural members, such as floor and roof slabs, which |
| DIAPHRAGMS | transmit inertial forces to lateral force resisting
members. |
| STRUCTURAL
WALLS | Walls designed to resist combinations of shears,
moments, and axial forces induced by earthquake
motions. A shear wall is a structural wall. |
| STRUT | An element of a structural diaphragm used to provide
continuity around an opening in the diaphragm. |
| TIE ELEMENTS | Elements used to transmit inertial forces and prevent
separation of building components. |
#### 8.1.1.2 Notation
* $A_{ch}$ = Cross-sectional area of a structural member measured out to out of transverse reinforcement, mm2
* $A_{cp}$ = Area of concrete section resisting shear of an individual pier or horizontal wall segment, mm2
* $A_{cv}$ = Net area of concrete section bounded by web thickness and length of section in the direction of shear force considered, mm2
* $A_g$ = Gross area of section, mm2
* $A_{j}$ = Effective cross-sectional area within a joint, see Sec 8.3.7.3, in a plane parallel to plane of reinforcement generating shear in the joint. The joint depth shall be the overall depth of the column. Where a beam frames into a support of larger width, the effective width of the joint shall not exceed the smaller of :
* (a) Beam width plus the joint depth
* (b) twice the smaller perpendicular distance from the longitudinal axis of the beam to the column side (See Sec 8.3.7.3)
* $A_{sh}$ = Total cross-sectional area of transverse reinforcement (including cross ties) within spacing $s$ and perpendicular to dimension $h_c$
* $E$ = Load effects of earthquake or related internal moments and forces $M_{pr}$ = Probable flexural moment strength of members, with or without axial load, determined using the properties of the member at the joint faces assuming a tensile strength in the longitudinal bars of at least 1.25 $f_y$ and a strength reduction factor $\phi$ of 1.0, N-mm
* $M_p$ = Portion of slab moment balanced by support moment $V_c$ = Nominal shear strength provided by concrete, N $V_e$ = Design shear force corresponding to the development of the probable moment strength of the member, N
* $V_n$ = Nominal shear strength, N $V_u$ = Factored shear force at section, N $b$ = Effective compressive flange width of a structural member, mm $b_w$ = Web width or diameter of circular section, mm $d$ = Distance from extreme compression fibre to centroid of longitudinal tension reinforcement, mm
* $d_b$ = Bar diameter, mm
* $f_c'$ = Specified compressive strength of concrete, MPa $f_y$ = Specified yield strength of reinforcement, MPa $f_{yt}$ = Specified yield strength of transverse reinforcement, MPa $h$ = Overall thickness or height of member, mm $h_c$ = Cross-sectional dimension of column core measured to the outside edge of the transverse reinforcement composing area $A_{sh}$ mm centre to centre of confining reinforcement
* $h_w$ = Height of entire wall (diaphragm) or of the segment of wall (diaphragm) considered, mm
* $h_x$ = Maximum centre to centre horizontal spacing of crossties or hoop legs on all faces of the column, mm
* $l_d$ = Development length in tension of deformed bar, deformed wire, plain and deformed welded wire reinforcement, mm
| $l_{dh}$ | = | Development length in tension of deformed bar or deformed wire
with a standard hook, measured from critical section to outside
end of hook \[straight embedment length between critical section
and start of hook (point of tangent) plus inside radius of bend and
one bar diameter], mm |
| ---------- | - | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| $l_0$ | = | Minimum length, measured from joint face along axis of structural
member, over which special transverse reinforcement must be
provided, mm |
| $l_w$ | = | Length of entire wall (diaphragm) or of segment of wall
(diaphragm) considered in the direction of shear force, mm |
| $s$ | = | Spacing of transverse reinforcement measured along longitudinal
axis of the structural member, mm |
| $s_0$ | = | Maximum spacing of transverse reinforcement, mm |
| $\alpha_c$ | = | Coefficient defining the relative contribution of concrete strength
to wall strength |
| $\rho$ | = | Ratio of tension reinforcement to member area = $A_s/bd$ |
| $\rho_g$ | = | Ratio of total reinforcement area to cross-sectional area of column |
| $\rho_n$ | = | Ratio of distributed shear reinforcement on a plane perpendicular
to plane of $A_{cv}$ |
| $\rho_s$ | = | Ratio of volume of spiral reinforcement to the core volume
confined by the spiral reinforcement (measured out to out of
spiral) |
| $\rho_v$ | = | $A_{sv}/A_{cv}$; where $A_{sv}$ is the projection on $A_{cv}$ of area of distributed
shear reinforcement crossing the plane of $A_{cv}$ |
| $\phi$ | = | Strength reduction factor. |
### 8.1.2 Standard Hooks and Minimum Bend Diameters
#### 8.1.2.1 Standard hooks
The term "standard hook" as used in this Code shall mean one of the following:
* (a) 180o bend plus an extension of at least 4 bar diameters, but not less than 65 mm at the free end of the bar.
* (b) 90o bend plus an extension of at least 12 bar diameters at the free end of the bar.
* (c) For stirrup and tie anchorage
* (i) For 16 mm diameter bar and smaller, a 90o bend plus an extension of at least 6 bar diameters at the free end of the bar,
* (ii) For 19 mm to 25 mm diameter bars, a 90o bend plus an extension of at least 12 bar diameters at the free end of the bar,
* (iii) For 25 mm diameter bar and smaller, a 135o bend plus an extension of at least 6 bar diameters at the free end of the bar,
* (iv) For closed ties and continuously wound ties, a 135o bend plus an extension of at least 6 bar diameters, but not less than 75 mm.
* (d) Seismic hook is defined as a hook on a stirrup, hoop, or crosstie having a bend not less than 135o , except that circular hoops shall have a bend not less than 90o . Hooks shall have a six-diameter (but not less than 75 mm) extension that engages the longitudinal reinforcement and projects into the interior of the stirrup or hoop.
#### 8.1.2.2 Minimum bend diameters
* (a) The minimum diameter of bend measured on the inside of the bar, for standard hooks other than for stirrups and ties in sizes of 10 mm to 16 mm diameter shall not be less than the values shown in Table 6.8.1.
Table 6.8.1: Minimum Diameters of Bend
| Bar Size | Minimum Diameter of Bend |
| ----------------------- | ------------------------ |
| 10 mm ≤ $d_b$ ≤ 25 mm | $6d_b$ |
| 25 mm \< $d_b$ ≤ 40 mm | $8d_b$ |
| 40 mm \< $d_b$ ≤ 57 mm | $10d_b$ |
* (b) For stirrups and tie hooks, inside diameter of bend shall not be less than 4 bar diameters for 16 mm diameter bar and smaller. For bars larger than 16 mm diameter, bend diameter shall be in accordance with Table 6.8.1.
* (c) Inside diameter of bend in welded wire reinforcement for stirrups and ties shall not be less than 4 bar diameters for deformed wire larger than ASTM MD40 size (ASTM A1022) and 2 bar diameters for all other wires. Bends with inside diameter of less than 8 bar diameters shall not be less than 4 bar diameters from nearest welded intersection.
### 8.1.3 Bending
#### 8.1.3.1
Unless otherwise permitted by the engineer, all reinforcement shall be bent cold.
#### 8.1.3.2
Reinforcement partially embedded in concrete shall not be bent in place, except as permitted by the engineer or as shown in the design drawings.
### 8.1.4 Surface Conditions of Reinforcement
#### 8.1.4.1
When concrete is placed, metal reinforcement shall be free from mud, oil, or other nonmetallic coatings that decrease bond. Epoxy-coating of steel reinforcement in accordance with standards referenced in this Code shall be permitted.
#### 8.1.4.2
Metal reinforcement with rust, mill scale, or a combination of both, shall be considered satisfactory, provided the minimum dimensions (including height of deformations) and weight of a hand-wire-brushed test specimen are not less than applicable ASTM specification requirements.
### 8.1.5 Placing of Reinforcement
#### 8.1.5.1
Reinforcement shall be accurately placed and adequately supported before concrete is placed, and shall be secured against displacement within tolerances permitted in Sec 8.1.5.2 below.
#### 8.1.5.2
Reinforcement shall be placed within the following tolerances unless otherwise specified by the engineer:
* (a) Tolerances for depth d, and minimum concrete cover in flexural members, walls and compression members shall be as set forth in Table 6.8.2.
Table 6.8.2: Tolerances for Placing Reinforcement
| Depth of | Tolerance ford | Tolerance for Minimum |
| --------- | -------------- | ---------------------- |
| Member, d | | Concrete Cover |
| d≤ 200 mm | ±10 mm | –10 mm |
| d> 200 mm | ±13 mm | –13 mm |
* (b) Notwithstanding the provision of (a) above, tolerance for the clear distance to formed soffits shall be minus 6 mm and tolerance for cover shall not exceed minus one third (1/3) of minimum concrete cover specified in the design drawings or specifications.
* (c) Tolerance for longitudinal location of bends and ends of reinforcement shall be ± 50 mm, except at discontinuous ends of brackets and corbels, where tolerance shall be ± 13 mm and at discontinuous ends of other members, where tolerance shall be ±25 mm. The tolerance for concrete cover of Sec 8.1.5.2a shall also apply at discontinuous ends of members.
#### 8.1.5.3
Welded wire reinforcement (with ASTM wire size not greater than MW30 or MD30) used in slabs not exceeding 3 m in span shall be permitted to be curved from a point near the top of slab over the support to a point near the bottom of slab at midspan, provided such reinforcement is either continuous over, or securely anchored at support.
#### 8.1.5.4
Welding of crossing bars shall not be permitted for assembly of reinforcement unless authorized by the engineer.
### 8.1.6 Spacing of Reinforcement
#### 8.1.6.1
The minimum clear spacing between parallel bars in a layer shall be equal to one bar diameter, but not less than 25 mm, or 1.33 times of maximum nominal size of coarse aggregate, whichever is larger.
#### 8.1.6.2
Where parallel reinforcement is placed in two or more layers, bars in the upper layers shall be placed directly above those in the bottom layer with clear distance between layers not less than 25 mm.
#### 8.1.6.3
For compression members, the clear distance between longitudinal bars shall be not less than 1.5 bar diameters nor 40 mm nor 1.33 times of maximum nominal size of coarse aggregate.
#### 8.1.6.4
Clear distance limitation between bars shall apply also to the clear distance between a contact lap splice and adjacent splices or bars.
#### 8.1.6.5
In walls and one-way slabs the maximum bar spacing shall not be more than three times the wall or slab thickness h nor 450 mm.
#### 8.1.6.6
For two-way slabs, maximum spacing of bars shall not exceed twice the slab thickness h nor 450 mm.
#### 8.1.6.7
For temperature steel, maximum spacing shall not exceed 5 times the slab thickness h nor 450 mm.
#### 8.1.6.8 Bundled bars
* (a) Groups of parallel reinforcing bars bundled in contact to act as a single unit shall be limited to four.
* (b) Bundled bars shall be enclosed within stirrups or ties.
* (c) Bars larger than 32 mm diameter shall not be bundled in beams.
* (d) Individual bars within a bundle terminated within the span of flexural members shall terminate at different points with at least 4001 stagger.
* (e) Where spacing limitations and minimum concrete cover are based on bar diameter $d_b$, a unit of bundled bars shall be treated as a single bar of a diameter derived from the equivalent total area.
### 8.1.7 Exposure Condition and Cover to Reinforcement
#### 8.1.7.1
The nominal concrete cover to all reinforcement (including links), maximum free water-cement ratio and minimum cement content required for various minimum concrete strengths used in different exposure conditions shall be as specified in Table 6.8.3. However, for mild environment, the minimum concrete cover specified in Sections 8.1.7.2 and 8.1.7.3 for various structural elements may be used.
#### 8.1.7.2 Cast-in-place concrete
* (a) Minimum concrete cover for concrete cast against and permanently exposed to earth shall be 75 mm.
* (b) Concrete exposed to earth or weather, the minimum clear cover shall be as under.
19 mm to 57 mm bar diameter: 50 mm 16 mm diameter bar and smaller: 40 mm
* (c) The following minimum concrete cover may be provided for reinforcement for concrete surfaces not exposed to weather or in contact with ground:
| Slabs, Walls: | Minimum Cover |
| ------------------------------------------------------------------------------------ | ------------- |
| 40 mm to 57 mm bar diameter | 40 |
| 36 mm bar diameter and smaller | 20 |
| Beams, Columns : | |
| Primary reinforcement, Ties,
stirrups,
spirals | 40 |
| Shells, folded plate members : | |
| 19 mm bar diameter and larger | 20 |
| 16 mm bar diameter and smaller | 16 |
| Table 6.8.3\*: Concrete Cover and other Requirements for Various Exposure Conditions | |
| Environ | Exposure Conditions | | M | inimu | m
r | N/m | m2 | |
| ---------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --- | --- | ----- | -------- | ------ | ------ | ------ |
| ment | | 20 | 25 | 30 | 35 | 40 | 45 | 50 |
| | | | N | omina | l cov | er(m | m) | |
| Mild | Concrete surfaces protected | | | | | | | |
| | against weather or aggressive
conditions | 30 | 25 | 20 | 20 | 20\*\* | 20\*\* | 20\*\* |
| ment | | 20 | 25 | 30 | 35 | 40 | 45 | 50 |
| | | | N | omin | al cove | r(m | m) | |
| Moderate | Concrete surface away from
severe rain Concrete subject to
condensation
Concrete
surfaces continuously under
water Concrete in contact with
non-aggressive soil | 40 | 35 | 30 | 25 | 20 | 20 | 20 |
| Severe | Concrete surfaces exposed to
severe rain, alternate wetting
and
drying
or
severe
condensation | | 45 | 40 | 30 | 25 | 25 | 20 |
| Very
severe | Concrete surfaces exposed to
sea water spray, corrosive
fumes | | | 50 | 40 | 30 | 30 | 25 |
| Extrem
e | Concrete surfaces exposed to
abrasive action, e.g. sea water
carrying solids or flowing
water with pH\<
4.5 or
machinery or vehicles | | | | 60 | 50 | 40 | 30 |
| Maximum | water/cement ratio | 0.5 | 0.5 | 0.5 | 0.45 | 0.45 | 0.40 | 0.40 |
| Minimum | cement content, (kg/m3) | 315 | 325 | 350 | 375 | 400 | 410 | 420 |
* This Table relates to aggregate of 20 mm nominal maximum size. \*\* May be reduced to 15 mm provided the nominal maximum aggregate size does not exceed 15 mm
#### 8.1.7.3 Precast concrete (manufactured under plant control conditions) :
(a) Concrete exposed to earth or weather:
| Bar diameter | Minimum cover, mm |
| ----------------------------------------- | -------------------- |
| Wall Panels: | |
| 40 mm to 57 mm diameter | 40 |
| 36 mm diameter bar and smaller | 20 |
| Other Members: | |
| 40 mm to 57 mm diameter | 50 |
| 19 mm to 36 mm diameter | 40 |
| 16 mm diameter bar and smaller | 30 |
| (b) Concrete not exposed to weather or in | contact with ground: |
| Slabs, Walls: | |
| 40 mm to 57 mm diameter | 30 |
| 36 mm diameter bar and smaller | 16 |
| Beams, columns : | |
| Primary reinforcement | 20 ≤db≤ 40 |
| Ties, stirrups, spiral | 15 |
| Shells, folded plate members : | |
| 19 mm diameter bar and larger | 16 |
| 16 mm diameter bar and smaller | 10 |
#### 8.1.7.4
For concrete cast against and permanently exposed to earth, minimum cover shall be 75 mm. If, concrete cover specified in Sec 8.1.7.1 (Table 6.8.3) conflicts with those specified in Sec 8.1.7.2 or Sec 8.1.7.3, the larger value shall be taken.
#### 8.1.7.5 Bundled Bars
Minimum concrete cover shall be equal to the equivalent diameter of the bundle, but need not be greater than 50 mm.
#### 8.1.7.6 Future Extension
Exposed reinforcement, inserts, and plates intended for bonding with future extensions shall be protected from corrosion.
#### 8.1.7.7 Fire Protection
If a thickness of cover for fire protection greater than the concrete covers specified in Sections 8.1.7.1 to 8.1.7.6 is required, such greater thicknesses shall be specified.
#### 8.1.7.8 Corrosive Environments
If a thickness of cover for corrosive environment or other severe exposure conditions greater than the concrete covers specified in Sections 8.1.7.1 to 8.1.7.6 is required, such greater thicknesses shall be specified. For corrosion protection, a specified concrete cover for reinforcement not less than 50 mm for walls and slabs and not less than 65 mm for other members may be used. For precast concrete members a specified concrete cover not less than 40 mm for walls and slabs and not less than 50 mm for other members may be used.
Minimum compressive strength of concrete $f_c'$ for the corrosive environment or other severe exposure conditions shall be 25 MPa with minimum cement of 400 kg per cubic meter. Coarse aggregate shall be 20 mm down well-graded stone chips and fine aggregate shall be coarse sand of minimum FM 2.20.
For any non-structural member like drop wall, railing, fins etc., 12 mm down well graded stone chips may be used as coarse aggregate.
Use of brick chips (khoa) as coarse aggregate is strictly prohibited for the corrosive environment or other severe exposure conditions.
Water cement ratio shall be between 0.4-0.45. Potable water shall be used for all concreting.
### 8.1.8 Reinforcement Details for Columns
#### 8.1.8.1 Offset Bars
Offset bent longitudinal bars shall conform to the following:
* (a) The maximum slope of inclined portion of an offset bar with axis of column shall not exceed 1 in 6.
* (b) Portions of bar above and below an offset shall be parallel to the axis of column.
* (c) Horizontal support at offset bends shall be provided by lateral ties, spirals, or parts of the floor construction. Horizontal support provided shall be designed to resist 1.5 times the horizontal component of the computed force in the inclined portion of the offset bars. Lateral ties or spirals, if used, shall be placed not more than 150 mm away from points of bend.
* (d) Offset bars shall be bent before placement in the forms (see Sec 8.1.3).
* (e) Where the face of the column above is offset 75 mm or more from the face of the column below, longitudinal bars shall not be permitted to be offset bent. The longitudinal bars adjacent to the offset column faces shall be lap spliced using separate dowels. Lap splices shall conform to Sec 8.2.14.
#### 8.1.8.2 Steel Cores
Load transfer in structural steel cores of composite compression members shall be provided by the following:
* (a) Ends of structural steel cores shall be accurately finished to bear at end bearing splices, with positive provision for alignment of one core above the other in concentric contact.
* (b) At end bearing splices, bearing shall be considered effective to transfer not more than 50 percent of the total compressive stress in the steel core.
* (c) Transfer of stress between column base and footing shall be designed in accordance with Sec 6.8.8.
* (d) Base of structural steel section shall be designed to transfer the total load from the entire composite member to the footing; or, the base shall be designed to transfer the load from the steel core only, provided ample concrete section is available for transfer of the portion of the total load carried by the reinforced concrete section to the footing by compression in the concrete and by reinforcement.
### 8.1.9 Lateral Reinforcement for Columns
#### 8.1.9.1
Lateral reinforcement for compression members shall conform to the provisions of Sections 8.1.9.3 and 8.1.9.4 below and where shear or torsion reinforcement is required, shall also conform to provisions of Sec 6.4.
#### 8.1.9.2
Lateral reinforcement requirements for composite columns shall conform to Sections 6.3.13.7 and 6.3.13.8 Chapter 6.
#### 8.1.9.3 Spirals
Spiral reinforcement for columns shall conform to Sec 6.3.9.3 Chapter 6 and to the following:
* (a) Spirals shall consist of evenly spaced continuous bar or wire of such size and so assembled as to permit handling and placing without distortion from designed dimensions.
* (b) Size of spirals shall not be less than 10 mm diameter for cast-in-place construction.
* (c) The minimum and maximum clear spacing between spirals shall be 25 mm and 75 mm respectively.
* (d) Anchorage of spiral reinforcement shall be provided by 1.5 extra turns of spiral bar or wire at each end of a spiral unit.
* (e) Splices in spiral reinforcement shall be lap splices of 48 spiral diameter for deformed uncoated bar or wire and 72 spiral diameter for other cases, but not less than 300 mm.
* (f) Spirals shall extend from the top of footing or slab in any storey to the level of the lowest horizontal reinforcement in members supported above.
* (g) Spirals shall extend above termination of spiral to bottom of slab or drop panel, where beams or brackets do not frame into all sides of a column.
* (h) Spirals shall extend to a level at which the diameter or width of capital is 2 times that of the column, in case of columns with capitals.
* (i) Spirals shall be held firmly in place and true to line.
#### 8.1.9.4 Ties
Tie reinforcement for compression members shall conform to the following:
* (a) All bars shall be enclosed by lateral ties, at least 10 mm diameter in size for longitudinal bars 32 mm diameter or smaller, and at least 12 mm diameter in size for 36 mm to 57 mm diameter and bundled longitudinal bars.
* (b) Vertical spacing of ties shall not exceed 16 longitudinal bar diameters or 48 tie diameters, or the least dimension of the compression members.
* (c) Ties shall be arranged such that every corner and alternate longitudinal bar shall have lateral support provided by the corner of a tie with an included angle not more than 135o . No vertical bar shall be farther than 150 mm clear on each side along the tie from such a laterally supported bar. Where longitudinal bars are located around the perimeter of a circle, a complete circular tie is allowed.
* (d) The lowest tie in any storey shall be placed within one-half the required tie spacing from the top most horizontal reinforcement in the slab or footing below. The uppermost tie in any storey shall be within one-half the required tie spacing from the lowest horizontal reinforcement in the slab or drop panel above.
* (e) Where beams or brackets provide concrete confinement at the top of the column on all (four) sides, top tie shall be within 75 mm of the lowest horizontal reinforcement in the shallowest of such beams or brackets.
* (f) Where anchor bolts are placed in the top of columns or pedestals, the bolts shall be enclosed by lateral reinforcement that also surrounds at least four vertical bars of the column or pedestal. The lateral reinforcement shall be distributed within 125 mm of the top of the column or pedestal, and shall consist of at least two 12 mm diameter bars or three 10 mm diameter bars.
* (g) Where longitudinal bars are arranged in a circular pattern, individual circular ties per specified spacing may be used.
### 8.1.10 Lateral Reinforcement for Beams
#### 8.1.10.1
Compression reinforcement in beams shall be enclosed by ties or stirrups satisfying the size and spacing limitations in Sec 8.1.9.4 above. Such ties or stirrups shall be provided throughout the distance where compression reinforcement is required.
#### 8.1.10.2
Lateral reinforcement for flexural framing members subject to stress reversals or to torsion at supports shall consist of closed ties, closed stirrups, or spirals extending around the flexural reinforcement.
#### 8.1.10.3
Closed ties or stirrups shall be formed in one piece by overlapping standard stirrup or tie end hooks around a longitudinal bar, or formed in one or two pieces lap spliced with a Class B splice (lap of 1.3$l_d$) or anchored in accordance with Sec 8.2.10.
### 8.1.11 Shrinkage and Temperature Reinforcement
#### 8.1.11.1
Where the flexural reinforcement extends in one direction only, reinforcement for shrinkage and temperature stresses shall be provided perpendicular to flexural reinforcement in structural slabs. Shrinkage and temperature reinforcement shall be provided in accordance with Sec 8.1.11.2 below.
#### 8.1.11.2
Deformed reinforcement conforming to Sec 5.3.2 Chapter 5 shall be provided in accordance with the following:
* (a) Area of shrinkage and temperature reinforcement shall provide at least the following ratios of reinforcement area to gross concrete area:
Slabs where reinforcement with = 275 N/mm2 or 350 0.0020 N/mm2 are used: Slabs where reinforcement with = 420 N/mm2 are used: $\frac{420}{f_y} \times 0.0018$ Slabs where reinforcement with exceeding 420 $\frac{420}{f_y} \times 0.0018$ N/mm2 are used:
In any case, the reinforcement ratio shall not be less than 0.0014.
* (b) Area of shrinkage and temperature reinforcement for brick aggregate concrete shall be at least 1.5 times that provided in (a) above.
* (c) Shrinkage and temperature reinforcement shall be spaced not farther apart than 5 times the slab thickness, nor 450 mm.
* (d) At all sections where required, reinforcement for shrinkage and temperature stresses shall develop the specified yield strength in tension in accordance with Sec 8.2.
### 8.1.12 Requirements for Structural Integrity
#### 8.1.12.1
In the detailing of reinforcement and connections, members of a structure shall be effectively tied together to improve integrity of the overall structure.
#### 8.1.12.2
The minimum requirements for cast-in-place construction shall be:
* (a) In one-way slab construction, at least one bottom bar shall be continuous or shall be spliced over the support with a Class A tension splice. At non-continuous supports, the bars may be terminated with a standard hook.
* (b) Beams at the perimeter of the structure shall have at least one-sixth of the tension reinforcement required for negative moment at the support, but not less than two bars and one-quarter of the positive moment reinforcement required at midspan, but not less than two bars made continuous over the span length passing through the region bounded by the longitudinal reinforcement of the column around the perimeter and tied with closed stirrups. Closed stirrups need not be extended through any joints. The required continuity may be provided with top reinforcement spliced at mid-span and bottom reinforcement spliced at or near the support with Class B tension splices.
* (c) When closed stirrups are not provided, in other than perimeter beams, at least one-quarter of the positive moment reinforcement required at mid-span, but not less than two bars shall pass through the region bounded by the longitudinal reinforcement of the column and shall be continuous or shall be spliced over the support with a Class B tension splice. At non-continuous supports the bars shall be anchored to develop at the face of the support using a standard hook.
#### 8.1.12.3
To effectively tie elements together, tension ties shall be provided in the transverse, longitudinal, and vertical directions and around the perimeter of the structure for precast concrete construction.
### 8.1.13 Connections
#### 8.1.13.1
Enclosure shall be provided for splices of continuing reinforcement and for anchorage of terminating reinforcement at connections of principal framing elements (such as beams and columns),
#### 8.1.13.2
External concrete or internal closed ties, spirals, or stirrups shall be used as enclosures at connections.
## 8.2 Development and Splices of Reinforcement
### 8.2.1 Development of Reinforcement - General
Calculated tension or compression stress in reinforcement at each section of reinforced concrete members shall be developed on each side of that section by embedment length, hook or mechanical device, or a combination thereof. Hooks may be used in developing bars in tension only.
### 8.2.2 Limitation
The values of $f_c'$ used in Sec 8.2 shall not exceed 8.3 MPa. In addition to requirements stated here that affect detailing of reinforcement, structural integrity requirements of Sec 8.1.12 shall be satisfied.
### 8.2.3 Development of Deformed Bars and Deformed Wires in Tension
#### 8.2.3.1
Development length for deformed bars and deformed wire in tension, $\ell_d$ shall be determined from either Sec 8.2.3.2 or Sec 8.2.3.3 and applicable modification factors of Sections 8.2.3.4 and 8.2.3.5, but $\ell_d$ shall not be less than 300 mm.
#### 8.2.3.2
For deformed bars or deformed wire, $\ell_d$ shall be as follows:
| Spacing and cover | 19 mm diameter and smaller bars and deformed wires | 20 mm diameter and larger bars |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------ | ------------------------------------------------------------------ |
| Clear spacing of bars or wires being developed or spliced not less than $d_b$, clear cover not less than $d_b$, and stirrups or ties throughout $\ell_d$ not less than the Code minimum
Or, Clear spacing of bars or wires being developed or spliced not less than $2d_b$ and clear cover not less than $d_b$ | $\left(\dfrac{f_y \psi_t \psi_e}{2.1\lambda\sqrt{f_c'}}\right)d_b$ | $\left(\dfrac{f_y \psi_t \psi_e}{1.7\lambda\sqrt{f_c'}}\right)d_b$ |
| Other cases | | $\left(\dfrac{f_y \psi_t \psi_e}{1.1\lambda\sqrt{f_c'}}\right)d_b$ |
#### 8.2.3.3
For deformed bars or deformed wire, $\ell_d$ shall be
$$
l_d = \left(\frac{f_y}{1.1\lambda\sqrt{f_c'}}\frac{\psi_t\psi_e\psi_s}{\left(\dfrac{c_b+K_{tr}}{d_b}\right)}\right)d_b \tag{6.8.1}
$$
In which the confinement term $\dfrac{c_b + K_{tr}}{d_b}$ shall not be taken greater than 2.5, and
$$
K_{tr} = \frac{40A_{tr}}{sn} \tag{6.8.2}
$$
Where, $n$ is the number of bars or wires being spliced or developed along the plane of splitting. It shall be permitted to use $K_{tr} = 0$ as a design simplification even if transverse reinforcement is present.
#### 8.2.3.4
The factors used in the expressions for development of deformed bars and deformed wires in tension in Sec 8.2.3 are as follows:
* (a) Where horizontal reinforcement is placed such that more than 300 mm of fresh concrete is cast below the development length or splice, $\psi_t = 1.3$. For other cases, $\psi_t = 1.0$.
* (b) For epoxy-coated bars or wires with cover less than $3d_b$, or clear spacing less than $6d_b$, $\psi_e = 1.5$. For all other epoxy-coated bars or wires, $\psi_e = 1.2$. For uncoated and zinc-coated (galvanized) reinforcement, $\psi_e = 1.0$. However, the product $\psi_t \psi_e$ need not be greater than 1.7.
* (c) For 19 mm diameter and smaller bars, and deformed wires, $\psi_s = 0.8$. For 20 mm diameter and larger bars, $\psi_t = 1.0$.
* (d) Where lightweight concrete is used, $\lambda$ shall not exceed 0.75 unless is specified (see Sec 6.1.9.1 Chapter 6). Where normal weight concrete is used, $\lambda = 1.0$.
#### 8.2.3.5 Excess Reinforcement
Development length may be reduced by the factor$\frac{\text{As required}}{\text{As provided}}$ where reinforcement in a flexural member is in excess of that required by analysis except where anchorage or development for is specifically required or the reinforcement is designed under the provisions of Sec 8.3.2(b).
### 8.2.4 Development of Deformed Bars and Deformed Wires in Compression
#### 8.2.4.1
Development length for deformed bars and deformed wire in compression, $\ell_d$ shall be determined from Sec 8.2.4.2 and applicable modification factors of Sec 8.2.4.3, but $\ell_d$ shall not be less than 200 mm.
#### 8.2.4.2
For deformed bars and deformed wire, $\ell_d$ shall be taken as the larger $\frac{0.24 f_y}{\lambda \sqrt{f_c'}} d_b$ of and $0.043 f_y d_b$ with $\lambda$ as given in Sec 8.2.3.4(d) and the constant 0.043 I\`±Å carries the unit of mm2 /N.
#### 8.2.4.3
Length $\ell_d$ in Sec 8.2.4.2 shall be permitted to be multiplied by the applicable factors for:
* (a) Reinforcement in excess of that required by analysis:
* (b) Reinforcement enclosed within spiral reinforcement not less than 6 mm diameter and not more than 100 mm pitch or within 12 mm diameter ties in conformance with Sec 8.1.9.4 and spaced at not more than 100 mm on center:
0.75
### 8.2.5 Development of Bundled Bars
#### 8.2.5.1
Development length of individual bars within a bundle, in tension or compression, shall be that for the individual bar, increased 20 percent for 3 bar bundles and 33 percent for 4 bar bundles.
#### 8.2.5.2
For determining the appropriate spacing and cover values in Sec 8.2.3.2, the confinement term in Sec 8.2.3.3, and the $\psi_e$ factor in Sec 8.2.3.4(b), a unit of bundled bars shall be treated as a single bar of a diameter derived from the equivalent total area and having a centroid that coincides with that of the bundled bars.
### 8.2.6 Development of Standard Hooks in Tension
#### 8.2.6.1
Development length $\ell_{dh}$ for deformed bars in tension terminating in a standard hook shall be computed as the product of the basic development length for deformed bars, $\ell_{dh}$ of Sec 8.2.6.2 below and the applicable modification factor(s) of Sec 8.2.6.3, but $\ell_{dh}$ shall be not less than $8d_b$ nor less than 150 mm.
#### 8.2.6.2
For deformed bars, $\ell_{dh}$ shall be $\dfrac{0.24\psi_e f_y}{\lambda\sqrt{f_c'}}d_b$ with $\psi_e$ taken as 1.2 for epoxy-coated reinforcement, and $\lambda$ taken as 0.75 for lightweight concrete. For other cases, $\psi_e$ and $\lambda$ shall be taken as 1.0.
#### 8.2.6.3
Length $\ell_{dh}$ in Sec 8.2.6.2 shall be permitted to be multiplied by the following applicable factors:
* (a) For 36 mm diameter bar and smaller hooks with side cover (normal to plane of hook) not less than 65 mm, 0.7
* and for 90o hook with cover on bar extension beyond hook not less than 50 mm
* (b) For 90o hooks of 36 mm diameter bar and smaller bars that are either enclosed within ties or stirrups perpendicular to the bar being developed, spaced not greater than 301 along $\ell_{dh}$; or enclosed within ties or 0.8 stirrups parallel to the bar being developed, spaced not greater than 301 along the length of the tail extension of the hook plus bend
* (c) For 180o hooks of 36 mm diameter bar and smaller bars that are enclosed within ties or stirrups 0.8
* perpendicular to the bar being developed, spaced not greater than 301 along $\ell_{dh}$.
* (d) Where anchorage or development for is not $\frac{\text{As required}}{\text{As provided}}$
* specifically required, reinforcement in excess of that $\frac{\text{As required}}{\text{As provided}}$
* required by analysis
In Sections 8.2.6.3(b) and 8.2.6.3(c), $d_b$ is the diameter of the hooked bar, and the first tie or stirrup shall enclose the bent portion of the hook, within 201 of the outside of the bend.
#### 8.2.6.4
For bars being developed by a standard hook at discontinuous ends of members with both side cover and top (or bottom) cover over hook less than 65 mm, the hooked bar shall be enclosed within ties or stirrups perpendicular to the bar being developed, spaced not greater than 301 along $\ell_{dh}$ . The first tie or stirrup shall enclose the bent portion of the hook, within 201 of the outside of the bend, where $d_b$ is the diameter of the hooked bar. For this case, the factors of Sec 8.2.6.3(b) and (c) shall not apply.
#### 8.2.6.5
Hooks shall not be considered effective in developing bars in compression.
### 8.2.7 Development of Flexural Reinforcement - General
#### 8.2.7.1
Tension reinforcement may be developed by bending across the web to be anchored or made continuous with reinforcement on the opposite face of member.
#### 8.2.7.2
Critical sections for development of reinforcement in flexural members are at points of maximum stress and at points within the span where adjacent reinforcement terminates, or is bent. In addition, the provisions of Sec 8.2.8.3 shall also be satisfied.
#### 8.2.7.3
Reinforcement shall extend beyond the point at which it is no longer required to resist flexure for a distance not less than $d$ nor less than $12d_b$, except at supports of simple spans and at free end of cantilevers.
#### 8.2.7.4
Continuing reinforcement shall have an embedment length not less than the development length $\ell_d$ beyond the point where the bent or terminated tension reinforcement is no longer needed to resist bending.
#### 8.2.7.5
No flexural bar shall be terminated in a tension zone unless one of the following conditions is satisfied:
* (a) $V_u$ at the location of termination is not over two-thirds of $\phi V_n$.
* (b) Stirrup area in excess of that normally required for shear and torsion is provided over a distance along each terminated bar or wire equal to $0.75d$ from the point of cut-off. Excess stirrup area $A_v$ shall be not less than $\dfrac{0.41b_ws}{f_{yt}}$. Spacing, $s$ shall not exceed $\dfrac{d}{8\beta_b}$, where $\beta_b$ is the ratio of area of reinforcement cut off to total area of tension reinforcement at the section.
* (c) For 36 mm diameter bar and smaller, the continuing bars provide twice the area required for flexure at the cut-off point and the shear $V_u$ does not exceed three-quarter of $\phi V_n$.
#### 8.2.7.6
Where the reinforcement stress is not directly proportional to moment, such as in sloped, stepped, or tapered footings, brackets, deep flexural members, or members in which tension reinforcement is not parallel to the compression face, adequate anchorage shall be provided for the tension reinforcement. See Sections 8.2.8.4 and 8.2.9.4 for deep flexural members.
### 8.2.8 Development of Positive Moment Reinforcement
#### 8.2.8.1
At least one-third of the positive moment reinforcement in simple members and one-fourth of the positive moment reinforcement in continuous members shall extend along the same face of member into the support. In beams, such reinforcement shall extend into the support at least 150 mm.
#### 8.2.8.2
When the flexural member is a part of the primary lateral load resisting system, positive moment reinforcement extended into the support by Sec 8.2.8.1 above shall be anchored to develop the specified yield strength in tension at the face of support.
#### 8.2.8.3
At simple supports and at points of inflection, positive moment tension reinforcement shall be limited to a diameter such that $\ell_d$ computed for $f_y$ by Sec 8.2.3 satisfies Eq. 6.8.3, except that Eq. 6.8.3 need not be satisfied for reinforcement terminating beyond the centreline of simple supports by a standard hook or a mechanical anchorage at least equivalent to a standard hook.
$$
l_d \leq \frac{M_n}{V_u} + l_a \tag{6.8.3}
$$
Where,
$M_n$ = nominal moment strength assuming all reinforcement at section to be stressed to $f_y$.
$V_u$ = factored shear force at section
$l_a$ = at a support, embedded length of bar beyond centre of support; at point of zero moment, shall be limited to d or $12d_b$, whichever is greater.
The value of $\dfrac{M_n}{V_u}$ may be increased 30 percent when the ends of reinforcement are confined by a compressive reaction.
Where,
$M_n$ = nominal moment strength assuming all reinforcement at section to be stressed to .
$V_u$ = factored shear force at section
$l_a$ = at a support, embedded length of bar beyond centre of support; at point of zero moment, shall be limited to d or 1201, whichever is greater.
The value of $M_n/V_u$ may be increased 30 percent when the ends of reinforcement are confined by a compressive reaction.
#### 8.2.8.4
At simple supports of deep beams, positive moment tension reinforcement shall be anchored to develop in tension at the face of the support except that if design is carried out using Appendix I, the positive moment tension reinforcement shall be anchored in accordance with Sec I.4.3 Appendix I. At interior supports of deep beams, positive moment tension reinforcement shall be continuous or be spliced with that of the adjacent spans.
### 8.2.9 Development of Negative Moment Reinforcement
#### 8.2.9.1
Negative moment reinforcement in a continuous, restrained, or cantilever member, or in any member of a rigid frame, shall be anchored in or through the supporting member by embedment length, hooks or mechanical anchorage.
#### 8.2.9.2
Negative moment reinforcement shall have an embedment length into the span as required by Sections 8.2.1, 8.2.2 and 8.2.7.3.
#### 8.2.9.3
At least one-third of the total tension reinforcement provided for negative moment at the support shall be extended beyond the point of inflection a distance not less than $d$, $12d_b$, or $l_n/16$, whichever is greater.
#### 8.2.9.4
At interior supports of deep flexural members, negative moment tension reinforcement shall be continuous with that of the adjacent spans.
### 8.2.10 Development of Shear Reinforcement
#### 8.2.10.1
Shear reinforcement shall be carried as close to compression and tension surfaces of member as cover requirements and proximity of other reinforcement permits.
#### 8.2.10.2
The ends of single leg, simple U, or multiple U-stirrups shall be anchored by one of the following means:
* (a) By a standard hook around longitudinal reinforcement for ASTM MD200 wires, and 16 mm diameter bars and smaller and for 19 mm to 25 mm diameter bars with $f_{yt} \leq 280$ N/mm2 .
* (b) For 19 mm to 25 mm diameter stirrups with $f_{yt}$ greater than 280 N/mm2 , a standard stirrup hook around a longitudinal bar plus an embedment between mid-height of the member and the outside end of the hook equal to or greater than $\dfrac{0.17d_b f_{yt}}{\lambda\sqrt{f_c'}}$.
* (c) For each leg of welded plain wire reinforcement forming simple U- stirrups, either: (i) Two longitudinal wires spaced at a 50 mm spacing along the member at the top of the U; or (ii) One longitudinal wire located not more than $d/4$ from the compression face and a second wire closer to the compression face and spaced not less than 50 mm from the first wire. The second wire shall be permitted to be located on the stirrup leg beyond a bend, or on a bend with an inside diameter of bend not less than $8d_b$.
* (d) For each end of a single leg stirrup of welded wire reinforcement, two longitudinal wires at a minimum spacing of 50 mm and with the inner wire at least the greater of $d/4$ or 50 mm from $d/2$. Outer longitudinal wire at tension face shall not be farther from the face than the portion of primary flexural reinforcement closest to the face.
* (e) In joist construction, for 13 mm diameter bar and ASTM MD130 wire and smaller, a standard hook.
#### 8.2.10.3
Each bend in the continuous portion of a simple U-stirrup or multiple U-stirrup shall enclose a longitudinal bar between anchored ends.
#### 8.2.10.4
If extended into the region of tension, longitudinal bars bent to act as shear reinforcement shall be continuous with longitudinal reinforcement and, if extended into a region of compression, shall be anchored beyond mid-depth $d/2$ as specified for development length in Sec 8.2.3 for that part of $f_{yt}$ required to satisfy Eq. 6.6.58.
#### 8.2.10.5
Pairs of U-stirrups or ties so placed as to form a closed unit shall be considered properly spliced when length of laps are 1.3$\ell_d$. In members at least 450 mm deep, such splices with $A_b f_{yt}$ not more than 40 kN per leg shall be considered adequate if stirrup legs extend the full available depth of member.
### 8.2.11 Development of Plain Bars
For plain bars, the minimum development length shall be twice that of deformed bars specified in Sections 8.2.1 to 8.2.10 above.
### 8.2.12 Splices of Reinforcement - General
#### 8.2.12.1
Splices of reinforcement shall be made only as required or permitted on design drawings, or in specifications, or as authorized by the engineer.
#### 8.2.12.2 Lap splices
* (a) Lap splices shall not be used for 36 mm diameter bars and larger, except as provided in Sections 8.2.14.2 Chapter 8 and 6.8.8.2.3 Chapter 6.
* (b) Lap splices of bundled bars shall be based on the lap splice length required for individual bars within the bundle, increased in accordance with Sec 8.2.5. Individual bar splices within a bundle shall not overlap. Entire bundles shall not be lap spliced.
* (c) Bars spliced by noncontact lap splices in flexural members shall not be spaced transversely farther apart than one-fifth the required lap splice length, nor 150 mm.
#### 8.2.12.3 Welded splices and mechanical connections
* (a) Welded splices and other mechanical connections are allowed.
* (b) Except as provided in this Code, all welding shall conform to "Structural Welding Code - Reinforcing Steel" (AWS D1.4).
* (c) Welded splices shall be butted and welded to develop in tension at least 125 percent of specified yield strength of the bar.
* (d) A full mechanical connection shall develop in tension or compression, as required, at least 125 percent of specified yield strength of the bar.
* (e) Welded splices and mechanical connections not meeting the requirements of (c) or (d) above are allowed only for 16 mm diameter bar or smaller and in accordance with Sec 8.2.13.4.
### 8.2.13 Splices of Deformed Bars and Deformed Wire in Tension
#### 8.2.13.1
The minimum length of lap for tension splices shall be as required for Class A or B splice, but not less than 300 mm, where the classification shall be as follows:
Where, $\ell_d$ is calculated in accordance with Sec 8.2.3 to develop but without the 300 mm minimum of Sec 8.2.3.1 and without the modification factor of Sec 8.2.3.5.
#### 8.2.13.2
Lap splices of deformed bars and deformed wire in tension shall be class B splices except that Class A splices are allowed when the area of reinforcement provided is at least twice that required by analysis over the entire length of the splice, and one-half or less of total reinforcement is spliced within the required lap length.
#### 8.2.13.3
Where area of reinforcement provided is less than twice that required by analysis, welded splices or mechanical connections used shall meet the requirements of Sec 8.2.12.3(c) or Sec 8.2.12.3(d) above.
#### 8.2.13.4
Welded splices or mechanical connections not meeting the requirements of Sec 8.2.12.3(c) or Sec 8.2.12.3(d) shall be permitted for 16 mm diameter bars or smaller if the following requirements are met:
* (a) Splices shall be staggered at least 600 mm and in such manner as to develop at every section at least twice the calculated tensile force at the section but not less than 140 N/mm2 for total area of reinforcement provided.
* (b) Spliced reinforcement stress shall be taken as the specified splice strength, in computing tensile force developed at each section, but not to exceed . Unspliced reinforcement stress shall be taken as a fraction of defined by the ratio of the shortest actual development length provided beyond the section to $\ell_d$ but not to be taken greater than .
#### 8.2.13.5
When bars of different size are lap spliced in tension, splice length shall be the larger of $\ell_d$ of larger bar and tension lap splice length of smaller bar.
#### 8.2.13.6
Splices in tension tie members shall be made with a full welded splice or full mechanical connection in accordance with Sec 8.2.12.3(c) or (d) and splices in adjacent bars shall be staggered at least 750 mm.
### 8.2.14 Splices of Deformed Bars in Compression
#### 8.2.14.1
The minimum length of lap for compression splice shall be $0.071 f_y d_b$ for equal to 420 N/mm2 or less or $(0.13 f_y - 24) d_b$ for greater than 420 N/mm2 , but not less than 300 mm. For $f_c'$ less than 21 N/mm2 , length of lap shall be increased by one-third.
#### 8.2.14.2
When bars of different diameters are lap spliced in compression, the splice length shall be the larger of the development length, $\ell_d$ of the larger bar, and the compression splice length of the smaller bar. Lap splices of 40 mm, 43 mm, 50 mm and 57 mm diameter bars to 36 mm diameter and smaller bars shall be permitted.
#### 8.2.14.3
Welded splices or mechanical connections used in compression shall satisfy the requirements of Sec 8.2.12.3(c) or Sec 8.2.12.3(d).
#### 8.2.14.4 End bearing splices
* (a) Compression splices for bars required to transmit compressive stress only may consist of end bearing of square cut ends held in concentric contact by a suitable device.
* (b) Bar ends shall terminate in flat surfaces within 1.5o of a right angle to the axis of the bars, and shall be fitted within 3 degrees of full bearing after assembly.
* (c) End bearing splices shall be used only in members containing closed ties, closed stirrups or spirals.
### 8.2.15 Special Splice Requirements for Columns
#### 8.2.15.1
Lap splices, butt welded splices, mechanical connections, or endbearing splices shall be used with the limitations of Sections 8.2.15.2 to 8.2.15.4 below. A splice shall satisfy the requirements for all load combinations for the column.
#### 8.2.15.2 Lap splices in columns
* (a) Lap splices shall conform to Sec 8.2.14.1, Sec 8.2.14.2, and where applicable to Sec 8.2.15.2(d) or Sec 8.2.15.2(e) below, where the bar stresses due to factored loads is compressive.
* (b) Where the bar stress due to factored loads is tensile and does not exceed 0.5 in tension, lap splices shall be Class B tension lap splices if more than one-half of the bars are spliced at any section, or Class A tension lap splices if half or fewer of the bars are spliced at any section and alternate lap splices are staggered by $\ell_d$.
* (c) Where the bar stress due to factored loads is greater than 0.5 in tension, lap splices shall be Class B tension lap splices.
* (d) In tied reinforced compression members, if throughout lap splice length ties have an effective area of at least 0.0015ℎ in both directions, lap splice length is permitted to be multiplied by 0.83, but lap length shall not be less than 300 mm. Tie legs perpendicular to dimension ℎ shall be used in determining effective area.
* (e) For spirally reinforced compression members, lap splice length of bars within a spiral is permitted to be multiplied by 0.75, but lap length shall not be less than 300 mm.
#### 8.2.15.3 Welded splices or mechanical connectors in columns
Welded splices or mechanical connectors in columns shall meet the requirements of Sec 8.2.12.3(c) or Sec 8.2.12.3(d).
#### 8.2.15.4 End bearing splices in columns
End bearing splices complying with Sec 8.2.14.4 may be used for column bars stressed in compression provided the splices are staggered or additional bars are provided at splice locations. The continuing bars in each face of the column shall have a tensile strength at least 0.25 times the area of the vertical reinforcement in that face.
### 8.2.16 Splices of Plain Bars
For plain bars, the minimum length of lap shall be twice that of deformed bars specified in Sections 8.2.12 to 8.2.15 above.
### 8.2.17 Development of headed and mechanically anchored deformed bars in tension
#### 8.2.17.1
Development length for headed deformed bars in tension, $\ell_d$ shall be determined from Sec 8.2.17.2. Use of heads to develop deformed bars in tension shall be limited to conditions satisfying (a) through (f):
* (a) Bar shall not exceed 420 MPa;
* (b) Bar size shall not exceed 36 mm diameter;
* (c) Concrete shall be normal weight;
* (d) Net bearing area of head -1U shall not be less than 4-1;
* (e) Clear cover for bar shall not be less than 201; and
* (f) Clear spacing between bars shall not be less than 401.
#### 8.2.17.2
For headed deformed bars, development length in tension $\ell_d$ shall be $0.19\dfrac{\psi_e f_y}{\sqrt{f_c'}}d_b$, where the value of $f_c'$ used to calculate $\ell_d$ shall not exceed 40 MPa, and factor $\psi_e$ shall be taken as 1.2 for epoxy-coated reinforcement and 1.0 for other cases. Where reinforcement provided is in excess of that required by analysis, except where development of $f_y$ is specifically required, a factor of $A_{s,required}/A_{s,provided}$ may be applied to the expression for $\ell_d$. Length $\ell_d$ shall not be less than the larger of $8d_b$ and 150 mm.
#### 8.2.17.3
Heads shall not be considered effective in developing bars in compression.
#### 8.2.17.4
Any mechanical attachment or device capable of developing of reinforcement is allowed, provided that test results showing the adequacy of such attachment or device are approved by the Engineer. Development of reinforcement shall be permitted to consist of a combination of mechanical anchorage plus additional embedment length of reinforcement between critical section and mechanical attachment or device.
### 8.2.18 Development of Welded Deformed Wire Reinforcement in Tension
#### 8.2.18.1
Development length for welded deformed wire reinforcement in tension, $\ell_d$ measured from the point of critical section to the end of wire shall be computed as the product of, $\ell_d$ from Sec 8.2.3.2 or Sec 8.2.3.3, times welded deformed wire reinforcement factor, $\psi_w$ from 8.2.18.2 or 8.2.18.3. It shall be permitted to reduce $\ell_d$ in accordance with Sec 8.2.3.5 when applicable, but $\ell_d$ shall not be less than 200 mm except in computation of lap splices by Sec 8.2.20. When using $\psi_w$ from Sec 8.2.18.2, it shall be permitted to use an epoxy-coating factor $\psi_e$ of 1.0 for epoxy-coated welded deformed wire reinforcement in Sections 8.2.3.2 and 8.2.3.3.
#### 8.2.18.2
For welded deformed wire reinforcement with at least one cross wire within $\ell_d$ and not less than 50 mm from the point of the critical section, $\psi_w$ shall be the greater of $\dfrac{f_y - 240}{f_y}$ and $\dfrac{5d_b}{s}$ but not greater than 1.0, where s is the spacing between the wires to be developed.
#### 8.2.18.3
For welded deformed wire reinforcement with no cross wires within $\ell_d$ or with a single cross wire less than 50 mm from the point of the critical section, $\psi_w$ shall be taken as 1.0, and $\ell_d$ shall be determined as for deformed wire.
#### 8.2.18.4
Where any plain wires, or deformed wires larger than ASTM D 31, are present in the welded deformed wire reinforcement in the direction of the development length, the reinforcement shall be developed in accordance with Sec 8.2.19.
### 8.2.19 Development of Welded Plain Wire Reinforcement in Tension
Yield strength of welded plain wire reinforcement shall be considered developed by embedment of two cross wires with the closer cross wire not less than 50 mm from the point of the critical section. However, $\ell_d$ shall not be less than
$$
\ell_d = 3.3\frac{A_b}{s}\frac{f_y}{\lambda\sqrt{f_c'}} \tag{6.8.4}
$$
Where $\ell_d$ is measured from the point of the critical section to the outermost crosswire, $s$ is the spacing between the wires to be developed, and $\lambda$ as given in Sec 8.2.3.4(d). Where reinforcement provided is in excess of that required, $\ell_d$ may be reduced in accordance with Sec 8.2.3.5. Length, $\ell_d$ shall not be less than 150 mm except in computation of lap splices by Sec 8.2.21.
### 8.2.20 Splices of Welded Deformed Wire Reinforcement in Tension
#### 8.2.20.1
Minimum lap splice length of welded deformed wire reinforcement measured between the ends of each reinforcement sheet shall be not less than the larger of 1.3$l_d$ and 200 mm, and the overlap measured between outermost cross wires of each reinforcement sheet shall be not less than 50 mm, where $\ell_d$ is calculated in accordance with Sec 8.2.18 to develop .
#### 8.2.20.2
Lap splices of welded deformed wire reinforcement, with no cross wires within the lap splice length, shall be determined as for deformed wire.
#### 8.2.20.3
Where any plain wires, or deformed wires larger than ASTM MD200, are present in the welded deformed wire reinforcement in the direction of the lap splice or where welded deformed wire reinforcement is lap spliced to welded plain wire reinforcement, reinforcement shall be lap spliced in accordance with Sec 8.2.21.
### 8.2.21 Splices of Welded Plain Wire Reinforcement in Tension
Minimum length of lap for lap splices of welded plain wire reinforcement shall be in accordance with Sections 8.2.21.1 and 8.2.21.2.
#### 8.2.21.1
Where - provided is less than twice that required by analysis at splice location, length of overlap measured between outermost cross wires of each reinforcement sheet shall be not less than the largest of one spacing of cross wires plus 50 mm, 1.5$l_d$ and 150 mm, where $\ell_d$ is calculated in accordance with Sec 8.2.19 to develop .
#### 8.2.21.2
Where - provided is at least twice that required by analysis at splice location, length of overlap measured between outermost cross wires of each reinforcement sheet shall not be less than the larger of 1.5$l_d$ and 50 mm, where $\ell_d$ is calculated in accordance with Sec 8.2.19 to develop .
## 8.3 Earthquake-Resistant Design Provisions
### 8.3.1 Scope
This section contains special requirements for design and construction of reinforced concrete members of a structure for which the design forces, related to earthquake motions, have been determined on the basis of energy dissipation in the nonlinear range of response.
### 8.3.2 Provisions
* (a) The provisions of Chapter 6, shall apply except as modified by the provisions of this Section.
* (b) Structures assigned to seismic design category SDC D (see Chapter 2), all reinforced concrete structures shall satisfy the requirements of special seismic detailing as given in Sections 8.3.3 to 8.3.8 in addition to the requirements of Chapter 6. The provisions for special moment frames shall not permit the use of slab without beam as part of seismic force-resisting system.
* (c) Structures assigned to SDC C (see Chapter 2), all reinforced concrete structures shall be built to satisfy the requirements of intermediate seismic detailing as given in Sec 8.3.10 in addition to the requirements of Chapter 6.
* (d) Structures assigned to SDC B (see Chapter 2), all reinforced concrete structures shall be built to satisfy the requirements of ordinary detailing as given in Sec 8.3.9 in addition to the requirements of Chapter 6.
* (e) Structures in lower SDCs are permitted to design with detailing provisions of higher SDCs to take advantage of lower design force levels.
### 8.3.3 General Requirements
#### 8.3.3.1 Analysis and proportioning of structural members
* (a) The interaction of all structural and nonstructural members shall be considered in the analysis.
* (b) Rigid members which are not a part of the lateral force resisting system are allowed provided their effect on the response of the system is considered and accommodated in the structural design. Consequences of failure of structural and nonstructural members which are not a part of the lateral force resisting system shall also be considered.
* (c) Structural members below base of structure required to transmit forces resulting from earthquake effects to the foundation shall also comply with the requirements of this section.
* (d) All structural members which are not a part of the lateral force resisting system shall conform to Sec 8.3.9.
#### 8.3.3.2 Strength reduction factors
Strength reduction factors shall be in accordance with Sections 6.2.3.2 to 6.2.3.4.
#### 8.3.3.3 Concrete in special moment frames and special structural walls
Compressive strength $f_c'$ of the concrete shall be not less than 21 N/mm2 . Specified compressive strength of light-weight concrete, $f_c'$ shall not exceed 35MPa unless demonstrated by experimental evidence. Modification factor λ for lightweight concrete in Sec 8.3 shall be in accordance with Sec 6.1.8 unless noted otherwise.
#### 8.3.3.4 Reinforcement in special moment frames and special structural walls
* (a) Requirements of Sec 8.3.3.4 shall apply to special moment frames, special structural walls and all components of special structural walls including coupling beams and wall piers.
* (b) Deformed reinforcement resisting earthquake-induced flexural and axial force, or both, shall comply with ASTM A706 Grade 420. Alternatively only BDS ISO 6935-2 Grades 300, 350, 400 and 420 or ASTM A615 Grades 275 and 420 reinforcement shall be permitted if:
* (i) The actual yield strength based on mill tests does not exceed by more than 125 N/mm2 (retests shall not exceed this value by more than an additional 20 N/mm2 ); and
* (ii) The ratio of the actual tensile strength to the actual yield strength is not less than 1.25.
* (iii) Minimum elongation in 200 mm shall be at least 14 percent for bar dia. 10 mm to 20 mm, at least 12 percent for bar dia. 22 mm through 36 mm, and at least 10 percent for bar dia. 40 mm to 60 mm.
* (c) The value of used to compute the amount of confinement reinforcement shall not exceed 700 N/mm2 .
* (d) The value of or used in design of shear reinforcement shall conform to Sec 6.4.3.2.
#### 8.3.3.5 Welding
Reinforcement required by factored load combinations which include earthquake effect shall not be welded except as specified in Sections 8.3.4.2(d) and 8.3.5.3(b). In addition, welding shall not be permitted on stirrups, ties, inserts, or other similar elements to longitudinal reinforcement required by design.
### 8.3.4 Flexural Members of Special Moment Frames
#### 8.3.4.1 Scope
Requirements of this section shall apply to special moment frame members; (i) resisting earthquake induced forces, and (ii) proportioned primarily to resist flexure. These frame members shall also satisfy the following conditions. The requirements are also shown in Figure 6.8.1.
* (a) Factored axial compressive force on frame member shall not exceed $0.1A_g f_c'$ .
* (b) Clear span for the member, $\ell_n$ shall not be less than four times its effective depth.
* (c) The width to depth ratio shall be at least 0.3.
* (d) The width shall not be (i) less than 250 mm and (ii) more than the width of the supporting member (measured on a plane perpendicular to the longitudinal axis of the flexural member) plus distances on each side of the supporting member neither exceeding three-fourths of the depth of the flexural member c1nor width of supporting member c2.
#### 8.3.4.2 Longitudinal reinforcement
* (a) At any section of a flexural member and for the top as well as for the bottom reinforcement, the amount of reinforcement shall be not less than $0.25\dfrac{f_c'}{f_y}b_wd$ or $1.4\dfrac{b_wd}{f_y}$ and the reinforcement ratio, $\rho$ shall not exceed 0.025 (Figure 6.8.2). At least two bars shall be provided continuously both top and bottom. The positive moment strength at the face of the joint shall be not less than one-half of the negative moment strength provided at that face as shown in Figure 6.8.2. Neither the negative nor the positive moment strength at any section along the member length shall be less than one-fourth the maximum moment strength provided at the face of either joint.
* (b) Lap splices of flexural reinforcement shall be permitted only if hoop or spiral reinforcement is provided over the lap length. Maximum spacing of the transverse reinforcement enclosing the lapped bars shall not exceed $d/4$ nor 100 mm. Lap splices shall not be used; (i) within the joints, (ii) within a distance of twice the member depth from the face of the joint, and (iii) at locations where analysis indicates flexural yielding caused by inelastic lateral displacements of the frame. These requirements are shown in Figure 6.8.3.
Welded splices and mechanical connections conforming to Sections 8.2.12.3(a) to 8.2.12.3(d) are allowed for splicing provided not more than alternate bars in each layer of longitudinal reinforcement are spliced at a section and the centre to centre distance between splices of adjacent bars is 600 mm or more measured along the longitudinal axis of the frame member. Welded splices and mechanical connections (Type 1) shall not be used within a distance equal to twice the member depth from the column or beam faces for special moment frames or from sections where yielding of the reinforcement is likely to occur as a result of inelastic lateral displacement.
![General requirements for flexural members of special moment frames showing dimensional limitations]()
![Flexural requirements for flexural members of special moment frames]()
Notes: (i) For beam bottom bars lap shall not be provided within a distance of twice the member depth from the face of the support; (ii) Preferred lap location of top bar is within middle third of the span but may be provided beyond 2h from the face of the support; (iii) Not more than 50% of the bars shall be spliced at one location; (iv) Lap splices are to be confined by stirrups with maximum spacing d/4 or 100 mm whichever is smaller.
![Lap splice requirements for flexural members of special moment frames]()
#### 8.3.4.3 Transverse reinforcement
* (a) Hoops shall be provided in the following regions of frame members:
* (i) At both ends of the flexural member, over a length equal to twice the member depth measured from the face of the supporting member toward midspan (Figure 6.8.4).
* (ii) Over lengths equal to twice the member depth (Figure 6.8.4), on both sides of a section where flexural yielding is likely to occur in connection with inelastic lateral displacements of the frame.
* (b) The first hoop shall be located not more than 50 mm from the face of the supporting member (Figure 6.8.4). Maximum spacing of the w
* hoops shall not exceed (i) î (ii) eight times the diameter of the smallest longitudinal bars, (iii) 24 times the diameter of the hoop bars, and (iv) 300 mm.
* (c) Where hoops are required, longitudinal bars on the perimeter shall have lateral support conforming to 8.1.9.4(c), and where hoops are not required, stirrups with seismic hooks shall be spaced not more w than q throughout the length of the member (Figure 6.8.4).
* (d) Hoops in flexural members are allowed to be made up of two pieces of reinforcement consisting of a U-stirrup having hooks not less than 135o with 6 diameter but not less than 75 mm extension anchored in the confined core and a cross tie to make a closed hoop (Figure 6.8.5). Consecutive cross ties engaging the same longitudinal bar shall have their 90o hooks at opposite sides of the flexural member. If the longitudinal reinforcing bars secured by the cross ties are confined by a slab only on one side of the flexural frame member, the 90o hooks of the cross ties shall all be placed on that side.
![Transverse reinforcement requirements for flexural members of special moment frames]()
![Hoop reinforcement requirements for flexural members of special moment frames]()
### 8.3.5 Special Moment Frame Members Subjected to Bending and Axial Load
#### 8.3.5.1 Scope
The requirements of this section shall apply to columns and other frame members serving to resist earthquake forces and having a factored axial force exceeding $0.1A_g f_c'$ . These frame members shall also satisfy the following conditions. The requirements are also shown in Figure 6.8.6.
* (a) The shortest cross-sectional dimension shall not be less than 300 mm.
* (b) The ratio of the shortest cross-sectional dimension to the perpendicular dimension shall not be less than 0.4.
![General requirements for special moment frames subjected to bending and axial load]()
#### 8.3.5.2 Minimum flexural strength of columns
* (a) Flexural strength of any column designed to resist a factored axial compressive force exceeding $0.1A_g f_c'$ shall satisfy (b) or (c) below. Lateral strength and stiffness of columns not satisfying (b) below shall be ignored in calculating the strength and stiffness of the structure but shall conform to Sec 8.3.9.
* (b) The flexural strength of the columns shall satisfy the following relation:
$$
\sum M_c \geq 1.2\sum M_g \tag{6.8.5}
$$
Where,
$\sum M_c$ = sum of nominal flexural strengths of columns framing into the joint, evaluated at the face of the joint. Column flexural strength shall be calculated for the factored axial force, consistent with the direction of lateral forces considered, resulting in the lowest flexural strength.
$\sum M_g$ = sum of nominal flexural strength of the beams framing into the joint evaluated at the face of the joint.
Flexural strengths shall be summed such that the column moments oppose the beam moments. Eq. 6.8.5 shall be satisfied for beam moments acting in both directions in the vertical plane of the frame considered.
* (c) If the requirements of (b) above is not satisfied at a joint, columns supporting reactions from that joint shall be provided with transverse reinforcement as specified in Sec 8.3.5.4 over their entire height.
#### 8.3.5.3 Longitudinal reinforcement
The provisions of longitudinal reinforcement are as shown in Figure 6.8.7 and stated as under.
* (a) The reinforcement ratio, $\rho$ shall not be less than 0.01 and shall not exceed 0.06.
* (b) Lap splices are permitted only within the centre half of the member length and shall be designed as tension splices. Welded splices and mechanical connections conforming to Sections 8.2.12.3(a) to 8.2.12.3(d) are allowed for splicing the reinforcement at any section provided not more than alternate longitudinal bars are spliced at a section and the distance between splices is 600 mm or more along the longitudinal axis of the reinforcement.
![Longitudinal reinforcement requirements for special moment frames]()
#### 8.3.5.4 Transverse reinforcement
* (a) Transverse reinforcement shall be provided as specified below and shown in Figures 6.8.8 and 6.8.9 unless a larger amount is required by Sec 8.3.8.
* (i) The volumetric ratio of spiral or circular hoop reinforcement, $\rho_s$ shall not be less than that indicated by the following equation:
$$
\rho_s = \frac{0.12f_c'}{f_{yt}} \tag{6.8.6}
$$
and shall not be less than that required by Eq. (6.6.12).
* (ii) The total cross-sectional area of rectangular hoop reinforcement shall not be less than that given by the following equations:
$$
A_{sh} = 0.3\left(\frac{sh_cf_c'}{f_{yt}}\right)\left(\frac{A_g}{A_{ch}} - 1\right) \tag{6.8.7}
$$
$$
A_{sh} = 0.09\left(\frac{sh_cf_c'}{f_{yt}}\right) \tag{6.8.8}
$$
* (iii) Transverse reinforcement shall be provided by either single or overlapping hoops or cross ties of the same bar size and spacing. Each end of the cross ties shall engage a peripheral longitudinal reinforcing bar. Consecutive cross ties shall be alternated end for end along the longitudinal reinforcement.
* (iv) If the design strength of member core satisfies the requirements of the specified loading combinations including earthquake effect, Eq. 6.8.7 and Eq. 6.6.12 need not be satisfied.
* (b) Spacing of transverse reinforcement along the length $\ell_o$ of the member shall not exceed the smallest of (i) one-quarter of the minimum dimension (ii) six time the diameter of the smallest longitudinal bar and (iii) $s_o = 100 + \dfrac{(350 - h_x)}{3}$. The value of $s_o$ shall not exceed 150 mm and need not be taken less than 100 mm.
* (c) Spacing of cross ties or legs of overlapping hoops shall not be more than 350 mm on centre in the direction perpendicular to the longitudinal axis of the member.
* (d) The volume of transverse reinforcement in amount specified in (a) through (c) above shall be provided over a length $\ell_o$ from each joint face and on both sides of any section where flexural yielding is likely to occur in connection with inelastic lateral displacements of the frame. The length $\ell_o$ shall not be less than (i) the depth of the member at the joint face or at the section where flexural yielding is likely to occur, (ii) one-sixth of the clear span of the member, and (iii) 450 mm.
* (e) If the factored axial force in columns supporting reactions from discontinued stiff members, such as walls, exceeds $0.1A_g f_c'$ they shall be provided with transverse reinforcement as specified in (a) through (c) above over their full height beneath the level at which the discontinuity occurs. Transverse reinforcement shall extend into the discontinued member for at least the development length of the largest longitudinal reinforcement in the column in accordance with Sec 8.3.7.4. If the lower end of the column terminates on a wall, transverse reinforcement as specified above shall extend into the wall for at least the development length of the largest longitudinal reinforcement in the column at the point of termination. If the column terminates on a footing or mat, transverse reinforcement as specified in above shall extend at least 300 mm into the footing or mat.
* (f) Where transverse reinforcement as specified in (a) through (c) above, is not provided throughout the full length of the column, the remainder of the column length shall contain spiral or hoop reinforcement with centre to centre spacing not exceeding the smaller of 6 times the diameter of the longitudinal column bars or 150 mm.
Note: In beam column joints where members frame into all four sides of the joint and each member width is at least three-fourths the column width, the spacing of transverse reinforcement shall be 150 mm within the overall depth of the shallowest frame member. For all other conditions spacing shall be $s_o$. Use hoops and cross ties in beam column joint.
![Transverse reinforcement requirements for rectangular hoops in special moment frame members subjected to bending and axial load]()
### 8.3.6 Special Structural Walls and Coupling Beams
#### 8.3.6.1 Scope
Requirements of Sec 8.3.6 apply to special structural walls and all components of special structural walls including coupling beams and wall piers forming part of the seismic-force-resisting system.
#### 8.3.6.2 Reinforcement
* (a) The distributed web reinforcement ratios, $\rho_l$ and $\rho_t$, for structural walls shall not be less than 0.0025, except that if $V_u$ does not exceed $0.083A_{cv}\lambda\sqrt{f_c'}$, $\rho_l$ and $\rho_t$ shall be permitted to be reduced to the values required as specified below. Reinforcement spacing each way in structural walls shall not exceed 450 mm. Reinforcement contributing to $V_n$ shall be continuous and shall be distributed across the shear plane.
* (i) Minimum ratio of vertical reinforcement area to gross concrete area, ρl, shall be:
| Deformed bar not larger than 16 mm diameter with $f_y$ not less than 420 MPa: | 0.0012 |
| ----------------------------------------------------------------------------- | ------ |
| Other deformed bars: | 0.0015 |
| Welded wire reinforcement not larger than ASTM MW 200 or MD 200: | 0.0012 |
* (ii) Minimum ratio of horizontal reinforcement area to gross concrete area, $\rho_t$, shall be:
| Deformed bar not larger than 16 mm diameter with $f_y$ not less than 420 MPa: | 0.0020 |
| ----------------------------------------------------------------------------- | ------ |
| Other deformed bars: | 0.0025 |
| Welded wire reinforcement not larger than ASTM MW 200 or MD 200: | 0.0020 |
* (b) At least two curtains of reinforcement shall be used in a wall if $V_u$ exceeds $0.17A_{cv}\lambda\sqrt{f_c'}$.
* (c) Reinforcement in structural walls shall be developed or spliced for $f_y$ in tension in accordance with Sec 8.2, except:
* (i) The effective depth of the member shall be permitted to be taken as $0.8\ell_w$ for walls where, reinforcement extended beyond the point at which it is no longer required to resist flexure for a distance equal to $d$ or $12d_b$, whichever is greater, except at supports of simple spans and at free end of cantilevers.
* (ii) The requirements of Sections 8.2.8, 8.2.9, and 8.2.10 need not be satisfied.
At locations where yielding of longitudinal reinforcement is likely to occur as a result of lateral displacements, development lengths of longitudinal reinforcement shall be 1.25 times the values calculated for in tension.
![Transverse reinforcement requirements for spiral hoops in special moment frame members]()
#### 8.3.6.3 Design forces
$V_u$ shall be obtained from the lateral load analysis in accordance with the factored load combinations.
#### 8.3.6.4 Shear strength
* (a) $V_n$ of structural walls shall not exceed
$$
V_n = A_{cv}\left(\alpha_c\lambda\sqrt{f_c'} + \rho_t f_y\right) \tag{6.8.9}
$$
Where, the coefficient $\alpha_c$ is 0.25 for $h_w/\ell_w \leq 1.5$, is 0.17 for $h_w/\ell_w \geq 2.0$, and varies linearly between 0.25 and 0.17 for $h_w/\ell_w$ between 1.5 and 2.0.
* (b) In Sec 8.3.6.4(a), the value of ratio $h_w/\ell_w$ used for determining $V_n$ for segments of a wall shall be the larger of the ratios for the entire wall and the segment of wall considered.
* (c) Walls shall have distributed shear reinforcement providing resistance in two orthogonal directions in the plane of the wall. If $h_w/\ell_w$ does not exceed 2.0, reinforcement ratio $\rho_l$ shall not be less than reinforcement ratio $\rho_t$.
* (d) For all vertical wall segments resisting a common lateral force, combined $V_n$ shall not be taken larger than $0.66A_{cv}\sqrt{f_c'}$, where, $A_{cv}$ is the gross combined area of all vertical wall segments. For any one of the individual vertical wall segments, $V_n$ shall not be taken larger than $0.83A_{cw}\sqrt{f_c'}$, where $A_{cw}$ is the area of concrete section of the individual vertical wall segment considered.
* (e) For horizontal wall segments as shown in Figure 6.8.10, including coupling beams, $V_n$ shall not be taken larger than $0.83A_{cw}\sqrt{f_c'}$, where $A_{cw}$ is the area of concrete section of a horizontal wall segment or coupling beam.
![Structural wall with openings showing horizontal wall segments and coupling beams]()
#### 8.3.6.5 Design for flexure and axial loads
* (a) Structural walls and portions of such walls subject to combined flexural and axial loads shall be designed in accordance with Sections 6.3.2 and 6.3.3 except that Sec 6.3.3.7 and the nonlinear strain requirements of Sec 6.3.2.2 shall not apply. Concrete and developed longitudinal reinforcement within effective flange widths, boundary elements, and the wall web shall be considered effective. The effects of openings shall be considered.
* (b) Unless a more detailed analysis is performed, effective flange widths of flanged sections shall extend from the face of the web a distance equal to the smaller of one-half the distance to an adjacent wall web and 25 percent of the total wall height.
#### 8.3.6.6 Boundary elements of special structural walls
* (a) The need for special boundary elements at the edges of structural walls shall be evaluated in accordance with Sec 8.3.6.6(b) or (c). The requirements of Sec 8.3.6.6(d) and (e) also shall be satisfied.
* (b) This section applies to walls or wall piers that are effectively continuous from the base of structure to top of wall and designed to have a single critical section for flexure and axial loads. Walls not satisfying these requirements shall be designed by Sec 8.3.6.6(c).
* (i) Compression zones shall be reinforced with special boundary elements where
$$
c \geq \frac{l_w}{600(\delta_u/h_w)} \tag{6.8.10}
$$
In Eq. 6.8.10, $c$ corresponds to the largest neutral axis depth calculated for the factored axial force and nominal moment strength consistent with the design displacement $\delta_u$. Ratio $\dfrac{\delta_u}{h_w}$ in Eq. 6.8.10 shall not be taken less than 0.007;
* (ii) Where special boundary elements are required by b(i), the special boundary element reinforcement shall extend vertically from the critical section a distance not less than the larger of $\ell_w$ or $\dfrac{M_u}{4V_u}$.
* (c) Structural walls not designed to the provisions of (b) shall have special boundary elements at boundaries and edges around openings of structural walls where the maximum extreme fiber compressive stress, corresponding to load combinations including earthquake effects, $E$, exceeds $0.2f_c'$. The special boundary element shall be permitted to be discontinued where the calculated compressive stress is less than $0.15f_c'$. Stresses shall be calculated for the factored forces using a linearly elastic model and gross section properties. For walls with flanges, an effective flange width as defined in Sec 8.3.6.5(b) shall be used.
* (d) Where special boundary elements are required by Sec 8.3.6.6(b) or (c), following (i) to (v) shall be satisfied as shown in Figure 6.8.11:
* (i) The boundary element shall extend horizontally from the extreme compression fiber a distance not less than the larger of $c - 0.1\ell_w$ and $\dfrac{c}{2}$, where $c$ is the largest neutral axis depth
* calculated for the factored axial force and nominal moment strength consistent with $\delta_u$;
* (ii) In flanged sections, the boundary element shall include the effective flange width in compression and shall extend at least 300 mm into the web;
* (iii) The boundary element transverse reinforcement shall satisfy the requirements of Sec 8.3.5.4 as shown in Figure 6.8.8, except Eq. 6.8.7 need not be satisfied and the transverse reinforcement spacing limit of 8.3.5.4.b(i) shall be one-third of the least dimension of the boundary element;
* (iv) The boundary element transverse reinforcement at the wall base shall extend into the support at least $\ell_d$ according to Sec 8.3.6.2(c), of the largest longitudinal reinforcement in the special boundary element unless the special boundary element terminates on a footing, mat, or pile cap, where special boundary element transverse reinforcement shall extend at least 300 mm into the footing, mat, or pile cap;
* (v) Horizontal reinforcement in the wall web shall extend to within 150 mm of the end of the wall. Reinforcement shall be anchored to develop $f_y$ in tension within the confined core of the boundary element using standard hooks or heads. Where the confined boundary element has sufficient length to develop the horizontal web reinforcement, and $\dfrac{A_v f_y}{s}$ of the web reinforcement is not greater than $\dfrac{A_{sh}f_{yt}}{s}$ of the boundary element transverse reinforcement parallel to the web reinforcement, it shall be permitted to terminate the web reinforcement without a standard hook or head.
* (e) Where special boundary elements are not required by Sec 8.3.6.6(b) or (c), (i) and (ii) shall be satisfied as shown in Figure 6.8.12:
* (i) If the longitudinal reinforcement ratio at the wall boundary is greater than $\dfrac{2.8}{f_y}$, boundary transverse reinforcement shall satisfy Sec 8.3.5.4.(a).(iii), Sec 8.3.5.4.(c) as shown in Figure 6.8.8 and Sec 8.3.6.6.(d).(i). The maximum longitudinal spacing of transverse reinforcement in the boundary shall not exceed 200 mm;
* (ii) Except when $V_u$ in the plane of the wall is less than $0.083A_{cv}\lambda\sqrt{f_c'}$, horizontal reinforcement terminating at the edges of structural walls without boundary elements shall have a standard hook engaging the edge reinforcement or the edge reinforcement shall be enclosed in U-stirrups having the same size and spacing as, and spliced to, the horizontal reinforcement.
![Development of wall horizontal reinforcement in confined boundary element]()
![Longitudinal reinforcement ratios for typical wall boundary conditions]()
#### 8.3.6.7 Coupling beams
* (a) Coupling beams with $\dfrac{\ell_n}{h} > 4$ shall satisfy the requirements of Sec 8.3.7. The provisions of Sec 8.3.7.1(c) and (d) need not be satisfied if it can be shown by analysis that the beam has adequate lateral stability.
* (b) Coupling beams with $\dfrac{\ell_n}{h} < 2$ and with $V_u$ exceeding $0.33A_{cw}\lambda\sqrt{f_c'}$, shall be reinforced with two intersecting groups of diagonally placed bars symmetrical about the midspan, unless it can be shown that loss of stiffness and strength of the coupling beams will not impair the vertical load-carrying ability of the structure, the egress from the structure, or the integrity of nonstructural components and their connections to the structure.
* (c) Coupling beams not governed by Sec 8.3.6.7(a) or (b) shall be permitted to be reinforced either with two intersecting groups of diagonally placed bars symmetrical about the midspan or according to Sections 8.3.7.2 to 8.3.7.4.
* (d) Coupling beams reinforced with two intersecting groups of diagonally placed bars symmetrical about the midspan shall satisfy (i), (ii), and either (iii) or (iv). Requirements of Sec 6.4.5 Chapter 6 shall not apply.
* (i) $V_n$ shall be determined by
$$
V_n = 2A_{vd}f_y\sin\alpha \leq 0.83A_{cw}\sqrt{f_c'} \tag{6.8.11}
$$
Where, α is the angle between the diagonal bars and the longitudinal axis of the coupling beam.
* (ii) Each group of diagonal bars shall consist of a minimum of four bars provided in two or more layers. The diagonal bars shall be embedded into the wall not less than 1.25 times the development length for in tension.
* (iii) Each group of diagonal bars shall be enclosed by transverse 1â
* reinforcement having out-to-out dimensions not smaller than1â q in the direction parallel to y^ and along the other sides,
* where y^ is the web width of the coupling beam. The transverse reinforcement shall satisfy Sec 8.3.5.4 as shown in Figure 6.8.8 and shall have spacing measured parallel to the diagonal bars satisfying Sec 8.3.5.4 and not exceeding six times the diameter of the diagonal bars, and shall have spacing of crossties or legs of hoops measured perpendicular to the diagonal bars not exceeding 350 mm. For the purpose of computing Ag for use in Figure 6.8.9 and Eq. 6.8.7, the concrete cover as required in Sec 8.1.7 shall be assumed on all four sides of each group of diagonal bars. The transverse reinforcement, or its alternatively configured transverse reinforcement satisfying the spacing and volume ratio requirements of the transverse reinforcement along the diagonals, shall continue through the intersection of the diagonal bars. Additional longitudinal and transverse reinforcement shall be distributed around the beam perimeter with total area in each direction not less than 0.002y^ and spacing not exceeding 300 mm as shown in Figure 6.8.13(a).
* (iv) Transverse reinforcement shall be provided for the entire beam cross section satisfying Sec 8.3.5.4 as shown in Figure 6.8.8, with longitudinal spacing not exceeding the smaller of 150 mm and six times the diameter of the diagonal bars, and with spacing of crossties or legs of hoops both vertically and horizontally in the plane of the beam cross section not exceeding 200 mm. Each crosstie and each hoop leg shall engage a longitudinal bar of equal or larger diameter. It shall be permitted to configure hoops as shown in Figure 6.8.13(b).
#### 8.3.6.8 Wall piers
* (a) Wall piers shall satisfy the special moment frame requirements for columns of Sec 8.3.5.3 with joint faces taken as the top and bottom of eâ
* the clear height of the wall pier. Alternatively, wall piers with > 1â
* 2.5 shall satisfy (i) to (vi) below:
* (i) Design shear force shall be determined in accordance with Sec 8.3.8.1 with joint faces taken as the top and bottom of the clear height of the wall pier. Where the Code includes provisions to account for overstrength of the seismic-force-resisting system, the design shear force need not exceed Ωo times the factored shear determined by analysis of the structure for earthquake effects.
* (ii) Vh and distributed shear reinforcement shall satisfy Sec 8.3.6.4.
* (iii) Transverse reinforcement shall be in the form of hoops except it shall be permitted to use single-leg horizontal reinforcement parallel to $\ell_w$, where only one curtain of distributed shear reinforcement is provided. Single-leg horizontal reinforcement shall have 180o bends at each end that engage wall pier boundary longitudinal reinforcement.
* (iv) Vertical spacing of transverse reinforcement shall not exceed 150 mm.
* (v) Transverse reinforcement shall extend at least 300 mm above and below the clear height of wall pier.
* (vi) Special boundary elements shall be provided if required by Sec 8.3.6.6(c).
* (b) For wall piers at the edge of a wall, horizontal reinforcement shall be provided in adjacent wall segments above and below the wall pier and be proportioned to transfer the design shear force from the wall pier into the adjacent wall segments as shown in Figure 6.8.14.
![Coupling beams with diagonally oriented reinforcement]()
![Required horizontal reinforcement in wall segments above and below wall piers at the edge of a wall]()
#### 8.3.6.9 Construction joints
All construction joints in structural walls shall conform to Sec 5.16.4 and contact surfaces shall be roughened as in Sec 6.4.5.9.
#### 8.3.6.10 Discontinuous walls
Columns supporting discontinuous structural walls shall be reinforced in accordance with Sec 8.3.5.4(e).
### 8.3.7 Joints of Special Moment Frames
#### 8.3.7.1 General requirements
* (a) Forces in longitudinal beam reinforcement at the faces of joints of reinforced concrete frames shall be determined for a stress of 1.25 in the reinforcement.
* (b) Joint strength shall be calculated by the appropriate strength reduction factors specified in Sec 6.2.3.1.
* (c) Beam longitudinal reinforcement terminated in a column shall be extended to the far face of the confined column core and anchored in tension as per Sec 8.3.7.4 below and in compression according to Sec 8.2.
* (d) Where longitudinal beam reinforcement extends through a beamcolumn joint, the column dimension parallel to the beam reinforcement shall not be less than 20 times the diameter of the largest longitudinal beam bar for normal-weight concrete. For lightweight concrete, the dimension shall not be less than 26 times the bar diameter.
#### 8.3.7.2 Transverse reinforcement
The provisions of transverse reinforcement are shown in Figures 6.8.15 and 6.8.16, stated as under.
* (a) As specified in Sec 8.3.5.4, transverse hoop reinforcement shall be provided within the joint, unless the joint is confined by structural members as specified in (b) below.
* (b) Within the depth of the shallowest framing member, transverse reinforcement equal to at least one-half the amount required by Sec 8.3.5.4(a) shall be provided where members frame into all four sides of the joint and where each member width is at least three-fourths the column width. At these locations, the spacing specified in Sec 8.3.5.4(b) may be increased to 150 mm.
* (c) As required by Sec 8.3.5.4, transverse reinforcement shall be provided through the joint to provide confinement for longitudinal beam reinforcement outside the column core if such confinement is not provided by a beam framing into the joint.
![General requirements and transverse reinforcement requirements for joints not confined by structural member]()
![Transverse reinforcement requirements for joints confined by structural member]()
#### 8.3.7.3 Shear Strength
The nominal shear strength for the joint shall be taken not greater than the forces specified below:
A member that frames into a face is considered to provide confinement to the joint if at least three-quarters of the face of the joint is covered by the framing member. A joint is considered to be confined if such confining members frame into all faces of the joint.
#### 8.3.7.4 Development length of bars in tension
* (a) The development length, $\ell_{dh}$, for bar sizes 10 mm to 36 mm in diameter with a standard 90o hook shall be not less than (i) $8d_b$, (ii) 150 mm, and (iii) the length required by Eq. 6.8.9.
$$
\ell_{dh} = \frac{f_yd_b}{5.4\sqrt{f_c'}} \tag{6.8.12}
$$
For light-weight concrete, $\ell_{dh}$ for a bar with a standard 90o hook shall not be less than (i) $10d_b$, (ii) 190 mm, and (iii) 1.25 times the length required by Eq. 6.8.12. The 90o hook shall be located within the confined core of a column or a boundary element.
* (b) For bar sizes 10 mm, to 36 mm diameter, the development length, $\ell_d$ for a straight bar shall be not less than (i) 2.5 times the length required by (a) above, if the depth of the concrete cast in one lift beneath the bar does not exceed 300 mm, and (ii) 3.5 times the length required by (a) above, if the depth of the concrete cast in one lift beneath the bar exceeds 300 mm.
* (c) Straight bars terminated at a joint shall pass through the confined core of a column or of a boundary member. Any portion of the straight embedment length not within the confined core shall be increased by a factor of 1.6.
### 8.3.8 Shear Strength Requirements
#### 8.3.8.1 Design forces
* (a) Frame Members Subjected Primarily to Bending: The design shear force ’! shall be determined from consideration of the maximum forces that can be generated at the faces of the joints at each of the member. It shall be assumed that moments of opposite sign corresponding to probable strength p\ act at the joint faces, and that the member is loaded with the factored tributary gravity load along its span.
* (b) Frame Members Subjected to Combined Bending and Axial Load: The design shear force ’! shall be determined from consideration of the maximum forces that can be generated at the faces of the joints at each end of the member. These joint forces shall be determined using the maximum probable moment strengths p\ of the member associated with the range of factored axial loads on the member. The member shears need not exceed those determined from joint strengths based on the probable moment strength p\ of the transverse members framing into the joint. In no case, ’! shall be less than the factored shear determined by the analysis of the structure.
* (c) Structural Walls and Diaphragms: The design shear force ’! shall be obtained from the lateral load analysis in accordance with the factored loads and combinations specified in Chapter 2, loads.
#### 8.3.8.2 Transverse reinforcement in frame members
* (a) For determining the required transverse reinforcement in frame members, the quantity $V_c$ shall be assumed to be zero if the factored axial compressive force including earthquake effects is less than $0.05A_gf_c'$ when the earthquake-induced shear forces, calculated in accordance with Sec 8.3.8.1(a), represents one-half or more of total design shear.
* (b) Stirrups or ties required to resist shear shall be closed hoops over lengths of members as specified in Sections 8.3.4.3, 8.3.5.4 and 8.3.7.2.
#### 8.3.8.3 Shear strength of special structural walls and diaphragms
* (a) Nominal shear strength of structural walls and diaphragms shall be determined using either (b) or (c) below.
* (b) Nominal shear strength, $V_n$ of structural walls and diaphragms shall be assumed not to exceed the shear force calculated from
$$
V_n = A_{cv}\left(0.17\lambda\sqrt{f_c'} + \rho_nf_y\right) \tag{6.8.13}
$$
* (c) For walls and wall segments having a ratio of $h_w/\ell_w$ less than 2.0, nominal shear strength of wall and diaphragm shall be determined from
$$
V_n = A_{cv}\left(\alpha_c\lambda\sqrt{f_c'} + \rho_nf_y\right) \tag{6.8.14}
$$
Where the coefficient $\alpha_c$ is 0.25 for $h_w/\ell_w \leq 1.5$, is 0.17 for $h_w/\ell_w \geq 2.0$, and varies linearly between 0.25 and 0.17 for $h_w/\ell_w$ between 1.5 and 2.0.
* (d) Value of ratio $h_w/\ell_w$ used in (c) above for determining $V_n$ for segments of a wall or diaphragm shall be the larger of the ratios for the entire wall (diaphragm) and the segment of wall (diaphragm) considered.
* (e) Walls and diaphragms shall have distributed shear reinforcement providing resistance in two orthogonal directions in the plane of the Zâ
* wall. If the ratio $h_w/\ell_w$ does not exceed 2.0, reinforcement ratio, $\rho_v$ shall not be less than reinforcement ratio $\rho_n$.
* (f) Nominal shear strength of all wall piers sharing a common lateral force shall not be assumed to exceed $0.67A_{cv}\sqrt{f_c'}$, where $A_{cv}$ is the total cross-sectional area, and the nominal shear strength of any one of the individual wall piers shall not be assumed to exceed $0.83A_{cp}\sqrt{f_c'}$
Where $A_{cp}$ represents the cross-sectional area of the pier considered.
* (g) Nominal shear strength of horizontal wall segments shall be assumed not to exceed $0.83A_{cp}\sqrt{f_c'}$ where $A_{cp}$ represents the cross-sectional area of a horizontal wall segment.
### 8.3.9 Ordinary Moment Frame Members not Proportioned to Resist Forces Induced by Earthquake Motion
#### 8.3.9.1 Induced moments
Frame members assumed not to contribute to lateral resistance shall be detailed according to (a) or (b) below depending on the magnitude of moments induced in those members when subjected to twice the lateral displacement under the factored lateral forces.
* (a) Members with factored gravity axial forces not exceeding $0.1A_g f_c'$ shall satisfy Sections 8.3.4.2(a) and 8.3.8.1(a) and members with factored gravity axial forces exceeding $0.1A_g f_c'$ shall satisfy Sections 8.3.5.4, 8.3.7.2(a) and 8.3.8.1(b) when the induced moment exceeds the design moment strength of the frame member.
* (b) The member shall satisfy Sec 8.3.4.2(a) when the induced moment does not exceed the design moment strength of the frame members.
#### 8.3.9.2 Tie requirements
All frame members with factored axial compressive forces exceeding $0.1A_g f_c'$ shall satisfy the following special requirements unless they comply with Sec 8.3.5.4.
* (a) Ties shall have hooks not less than 135o with extensions not less than 6 tie bar diameter or 60 mm. Cross ties as defined in Sec 8.3.2 are allowed.
* (b) The maximum tie spacing shall be $s_o$ over a length $\ell_o$ measured from the joint face. The spacing $s_o$ shall be not more than (i) eight diameters of the smallest longitudinal bar enclosed, (ii) 24 tie bar diameters, and (iii) one-half the least cross-sectional dimension of the column. The length $\ell_o$ shall not be less than (i) one-sixth of the clear height of the column, (ii) the maximum cross-sectional dimension of the column, and (iii) 450 mm.
* (c) The first tie shall be within a distance equal to $0.5s_o$ from the face of the joint.
* (d) The tie spacing shall not exceed $2s_o$ in any part of the column.
### 8.3.10 Requirements for Intermediate Moment Frames
#### 8.3.10.1 Scope
For structures assigned to SDC C, structural frames proportioned to resist forces induced by earthquake motions shall satisfy the requirements of Sec 8.3.10 in addition to those of Chapter 6.
#### 8.3.10.2 Reinforcement requirements
Reinforcement details in a frame member shall satisfy 8.3.10.4 below if the factored compressive axial load for the member does not exceed $0.1A_g f_c'$ . If the factored compressive axial load is larger, frame reinforcement details shall satisfy Sec 8.3.10.5 below unless the member has spiral reinforcement according to Eq. 6.6.12. If a two-way slab system without beams is treated as part of a frame resisting earthquake effect, reinforcement details in any span resisting moments caused by lateral force shall satisfy Sec 8.3.10.6 below.
#### 8.3.10.3 Shear requirements
Design shear strength of beams and columns resisting earthquake effect, E, shall not be less than the smaller of (i) sum of the shear associated with development of nominal moment strengths of the member at each restrained end of clear span and the shear calculated for factored gravity loads, or (ii) maximum shear obtained from design load combinations that include E, with the E assumed to be twice that prescribed by this Code.
#### 8.3.10.4 Beams
* (a) The positive moment strength at the face of the joint shall not be less than one-third the negative moment strength provided at that face (Figure 6.8.17). Neither the negative nor positive moment strength at any section along the length of the member shall be less than onefifth of the maximum moment strength provided at the face of either joint.
* (b) At both ends of the member, stirrups shall be provided over lengths equal to twice the member depth measured from the face of the supporting member toward midspan (Figure 6.8.18). The first stirrup shall be located not more than 50 mm from the face of the supporting member. Maximum stirrup spacing shall not exceed (a) $d/4$ (b) 8 times the diameter of the smallest longitudinal bar enclosed, (c) 24 times the diameter of the stirrup bar, and (d) 300 mm.
* (c) Stirrups shall be placed at not more than $d/2$ throughout the length of the member.
![Flexural requirements for beams in intermediate moment frames (IMF)]()
#### 8.3.10.5 Columns
* (a) Maximum tie spacing shall not exceed $s_o$ over a length $\ell_o$ measured from the joint face. The spacing $s_o$ shall not exceed (i) 8 times the diameter of the smallest longitudinal bar enclosed, (ii) 24 times the diameter of the tie bar, (iii) one-half of the smallest cross-sectional dimension of the frame member, and (iv) 300 mm. The length $\ell_o$ shall not be less than (i) one-sixth of the clear span of the member, (ii) maximum cross-sectional dimension of the member, and (iii) 450 mm.
* (b) The first tie shall be located not more than $s_o/2$ from the joint face.
* (c) Joint reinforcement shall conform to Sec 6.4.9.
* (d) Tie spacing shall not exceed $2s_o$ throughout the length of the member.
These requirements are shown in Figure 6.8.19.
![Transverse reinforcement requirements for beams in intermediate moment frames (IMF)]()
#### 8.3.10.6 Two-way slabs without beams
* (a) The factored slab moment at the supports relating to earthquake effect shall be determined for load combinations specified in Chapter 2, Loads. All reinforcement provided to resist the portion of slab moment balanced by support moment shall be placed within the column strip defined in Sec 6.5.2.1 (Figure 6.8.20).
* (b) The fractional part of the column strip moment shall be resisted by reinforcement placed within the effective width (Figure 6.8.20) specified in Sec 6.5.5.3.2.
* (c) Not less than one-half of the total reinforcement in the column strip at the support shall be placed within the effective slab width (Figure 6.8.15) specified in Sec 6.5.5.3.2.
* (d) Not less than one-quarter of the top steel at the support in the column strip shall be continuous throughout the span (Figure 6.8.21).
* (e) Continuous bottom reinforcement in the column strip shall be not less than one-third of the top reinforcement at the support in the column strip.
* (f) Not less than one-half of all bottom reinforcement at midspan shall be continuous and shall develop its yield strength at the face of support (Figure 6.8.22).
* (g) At discontinuous edges of the slab all top and bottom reinforcement at the support shall be developed at the face of the support (Figures 6.8.21 and 6.8.22).
* (h) For edge and corner connections flexural reinforcement perpendicular to the edge is not considered fully effective unless it is placed within the effective slab width as shown in Figure 6.8.23.
![Transverse reinforcement requirements for columns in intermediate moment frames (IMF)]()
![Reinforcement details at support of two-way slabs without beams]()
![Reinforcement details in column strip of two-way slabs without beams]()
![Reinforcement details in middle strip of two-way slabs without beams]()
![Effective width for reinforcement placement in edge and corner connections]()
### 8.3.11 Requirements for Foundation
#### 8.3.11.1 Scope
Foundations resisting earthquake induced forces or transferring earthquakeinduced forces between structure and ground in structures assigned to SDC D shall comply with Sec 8.3.11 and other applicable Code provisions.
The provisions in this section for piles, drilled piers, caissons, and slabs-onground shall supplement other applicable Code design and construction criteria.
#### 8.3.11.2 Footings, foundation mats, and pile caps
* (a) Longitudinal reinforcement of columns and structural walls resisting forces induced by earthquake effects shall extend into the footing, mat, or pile cap, and shall be fully developed for tension at the interface.
* (b) Columns designed assuming fixed-end conditions at the foundation shall comply with Sec 8.3.11.2(a) and, if hooks are required, longitudinal reinforcement resisting flexure shall have 90o hooks near the bottom of the foundation with the free end of the bars oriented toward the centre of the column.
* (c) Columns or boundary elements of special structural walls that have an edge within one-half the footing depth from an edge of the footing shall have transverse reinforcement in accordance with Sec 8.3.5.4 provided below the top of the footing. This reinforcement shall extend into the footing, mat, or pile cap and be developed for in tension.
* (d) Where earthquake effects create uplift forces in boundary elements of special structural walls or columns, flexural reinforcement shall be provided in the top of the footing, mat, or pile cap to resist actions resulting from the design load combinations, and shall not be less than required by Sec 6.3.5.
#### 8.3.11.3 Grade beams and slabs-on-ground
* (a) Grade beams designed to act as horizontal ties between pile caps or footings shall have continuous longitudinal reinforcement that shall be developed within or beyond the supported column or anchored within the pile cap or footing at all discontinuities.
* (b) Grade beams designed to act as horizontal ties between pile caps or footings shall be proportioned such that the smallest cross-sectional dimension shall be equal to or greater than the clear spacing between connected columns divided by 20, but need not be greater than 450 mm. Closed ties shall be provided at a spacing not to exceed the lesser of one-half the smallest orthogonal cross-sectional dimension and 300 mm.
* (c) Grade beams and beams that are part of a mat foundation subjected to flexure from columns that are part of the seismic-force-resisting system shall conform to Sec 8.3.4.
* (d) Slabs-on-ground that resist seismic forces from walls or columns that are part of the seismic-force-resisting system shall be designed as structural diaphragms in accordance with Sec 8.3.6. The design drawings shall clearly state that the slab on ground is a structural diaphragm and part of the seismic-force-resisting system.
#### 8.3.11.4 Piles, piers, and caissons
* (a) Provisions of Sec 8.3.11.4 shall apply to concrete piles, piers, and caissons supporting structures designed for earthquake resistance.
* (b) Piles, piers, or caissons resisting tension loads shall have continuous longitudinal reinforcement over the length resisting design tension forces. The longitudinal reinforcement shall be detailed to transfer tension forces within the pile cap to supported structural members as shown in Figure 6.8.24.
* (c) Where tension forces induced by earthquake effects are transferred between pile cap or mat foundation and precast pile by reinforcing bars grouted or post-installed in the top of the pile, the grouting system shall have been demonstrated by test to develop at least 1.25fy of the bar.
* (d) Piles, piers, or caissons shall have transverse reinforcement, Figure 6.8.24, in accordance with Sec 8.3.5.4 at locations
* (i) Top of the member for at least 5 times the member crosssectional dimension, but not less than 1.8 m below the bottom of the pile cap;
* (ii) Portion of piles in soil that is not capable of providing lateral support, or in air and water, along the entire unsupported length plus the length required in (i).
* (e) For precast concrete driven piles, the length of transverse reinforcement provided shall be sufficient to account for potential variations in the elevation in pile tips.
* (f) Concrete piles, piers, or caissons in foundations supporting one- and two-story stud bearing wall construction are exempt from the transverse reinforcement requirements of Sec 8.3.11.4(d) and (e).
* (g) Pile caps incorporating batter piles shall be designed to resist the full compressive strength of the batter piles acting as short columns. The slenderness effects of batter piles shall be considered for the portion of the piles in soil that is not capable of providing lateral support, or in air or water.
![Spiral details of cast-in-situ pile in seismic zone 4 and SDC D]()
### 8.3.12 Requirement Members not Designated as Part of the Seismic-ForceResisting System
#### 8.3.12.1 Scope
* (a) Requirements of Sec 8.3.12 apply to frame members not designated as part of the seismic-force-resisting system in structures assigned to SDC D.
Frame members assumed not to contribute to lateral resistance, except two-way slabs without beams, shall be detailed according to Sec 8.3.12.2 or Sec 8.3.12.3 depending on the magnitude of moments induced in those members when subjected to the design displacement $\delta_u$ . If effects of $\delta_u$ are not explicitly checked, it shall be permitted to apply the requirements of Sec 8.3.12.3. For two-way slabs without beams, slab-column connections shall meet the requirements of Sec 8.3.12.5.
#### 8.3.12.2 Induced moment and shear do not exceed design capacities
Where the induced moments and shears under design displacements, $\delta_u$, combined with the factored gravity moments and shears do not exceed the design moment and shear strength of the frame member, the conditions of Sections 8.3.12.2(a), 8.3.12.2(b), and 8.3.12.2(c) shall be satisfied. The gravity load combinations of (1.2D + 1.0L + 0.2S) or 0.9D, whichever is critical, shall be used. The load factor on the live load, L, shall be permitted to be reduced to 0.5 except for garages, areas occupied as places of public assembly, and all areas where L is greater than 4.8 kN/m2 .
* (a) Members with factored gravity axial forces not exceeding $\dfrac{A_g f_c'}{10}$ shall satisfy Sec 8.3.4.2(a). Stirrups shall be spaced not more than $d/2$ throughout the length of the member.
* (b) Members with factored gravity axial forces exceeding $\dfrac{A_g f_c'}{10}$ shall satisfy Sections 8.3.5.3(a) and 8.3.5.4. The maximum longitudinal spacing of ties shall be $s_o$ for the full member length. Spacing $s_o$ shall not exceed the smaller of six diameters of the smallest longitudinal bar enclosed and 150 mm.
* (c) Members with factored gravity axial forces exceeding $0.35P_o$ shall satisfy Sec 8.3.12.2(b). The amount of transverse reinforcement provided shall be one-half of that required by Sec 8.3.5.4(a) but shall not be spaced greater than $s_o$ for the full member length.
#### 8.3.12.3 Induced moment or shear exceeds design capacities
If the induced moment or shear under design displacements, $\delta_u$ exceeds $\phi M_n$ or $\phi V_n$ of the frame member, or if induced moments are not calculated, the conditions of Sec 8.3.12.3(a), (b) and (c) shall be satisfied.
* (a) Materials shall satisfy 8.3.3.3 and 8.3.3.4. Welded splices shall satisfy 8.3.3.5.
* (b) Members with factored gravity axial forces not exceeding $\dfrac{A_g f_c'}{10}$ shall satisfy Sections 8.3.4.2 and 8.3.8. Stirrups shall be spaced at not more than $d/2$ throughout the length of the member.
* (c) Members with factored gravity axial forces exceeding $\dfrac{A_g f_c'}{10}$ shall satisfy Sections 8.3.5.3, 8.3.5.4, 8.3.7.1 and 8.3.8.
#### 8.3.12.4 Two-way slabs without beams
For slab-column connections of two-way slabs without beams, slab shear reinforcement satisfying the requirements of Sections 6.4.10.3 and 6.4.10.5 and providing $V_s$ not less than $0.29\sqrt{f_c'}\,b_od$ shall extend at least four times the slab thickness from the face of the support, unless either (i) or (ii) is satisfied :
* (i) The requirements of Sec 6.4.10.7 using the design shear $V_{ug}$ and the induced moment transferred between the slab and column under the design displacement;
* (ii) The design story drift ratio does not exceed the larger of 0.005 and $\left[0.035 - 0.05\left(\dfrac{V_{ug}}{\phi V_c}\right)\right]$.
Design story drift ratio shall be taken as the larger of the design story drift ratios of the adjacent stories above and below the slab-column connection. $V_c$ is defined in Sec 6.4.10.2. $V_{ug}$ is the factored shear force on the slab critical section for two-way action, calculated for the load combination 1.2D + 1.0L + 0.2S.
The load factor on the live load, L, shall be permitted to be reduced to 0.5 except for garages, areas occupied as places of public assembly, and all areas where L is greater than 4.8 kN/m2 .
# Chapter 9: Prestressed Concrete Structures
Source: https://docs.sayed.app/bnbc/part-6-structural-design/chapter-9-prestressed-concrete-structures
## 9.1 General
The Prestressed Concrete Structures Chapter of the Code is divided into the following three Divisions:
Division A : Design
Division B : Material and Construction
Division C : Maintenance
Division A : Scope, Definitions, Notation, Design And Analysis (Sections 9.2 To 9.18)
## 9.2 Scope
### 9.2.1
Provisions of this Chapter shall apply to members prestressed with wires, strands, or bars conforming to the specifications of prestressing tendons given in Sec 9.5.1.3.
### 9.2.2
All provisions of this Code not specifically excluded, and not in conflict with provisions of this Chapter 9, shall apply to prestressed concrete.
## 9.3 Definitions, Symbols and Notation
### 9.3.1 Definitions
ACTION Mechanical force or environmental effect to which the structure (or structural component) is subjected. ANALYSIS Acceptable methods of evaluating the performance indices or verifying the compliance of specific criteria.
ANCHORAGE In post-tensioning, a mechanical device used to anchor the tendon to the concrete; in pretensioning, a device used to anchor the tendon until the concrete has reached a pre-determined strength, and the prestressing force has been transferred to the concrete; for reinforcing bars, a length of reinforcement, or a mechanical anchor or hook, or combination thereof at the end of a bar needed to transfer the force carried by the bar into the concrete.
| ANCHORAGE
BLISTER | A build-up area on the web, flange, or flange-web
junction for the incorporation of tendon anchorage
fittings. |
| ---------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| ANCHORAGE
ZONE | The portion of the structure in which the prestressing
force is transferred from the anchorage device on to the
local zone of the concrete, and then distributed more
widely in the general zone of the structure. |
| AT JACKING | At the time of tensioning the prestressing tendons. |
| AT LOADING | The maturity of the concrete when loads are applied.
Such loads include prestressing forces and permanent
loads but generally not live loads. |
| AT TRANSFER | Immediately after the transfer of prestressing force to
the concrete. |
| AUTOGENEOUS
SHRINKAGE | Volume decrease due to loss of water in the hydration
process causing negative pore pressure in concrete. |
| BIOLOGICAL
DEGRADATION | The physical or chemical degradation of concrete due to
the effect of organic matters such as bacteria, lichens,
fungi, moss, etc. |
| BONDED
MEMBER | A prestressed concrete member in which tendons are
bonded to the concrete either directly or through
grouting. |
| BONDED POST-
TENSIONING | Post-tensioned construction in which the annular space
around the tendons is grouted after stressing, thereby
bonding the tendon to the concrete section. |
| BONDED TENDON | Prestressing tendon that is bonded to concrete either
directly or through grouting. |
| BURSTING FORCE | Tensile forces in the concrete in the vicinity of the
transfer or anchorage of prestressing forces. |
| CAST-IN-PLACE
CONCRETE | Concrete placed in its final position in the structure
while still in a plastic state. |
| CHARACTERISTIC
STRENGTH | Unless otherwise stated in this Code, the characteristic
strength of material refers to the value of the strength
below which none of the test results should fall below by
more than 15% or 3.5 MPa for ≤35 MPa concrete, and
10% or 3.5 MPa for ≥35 MPa concrete, whichever is
larger. |
| CHEMICAL
ADMIXTUREs | Admixtures which are usually used in small quantities
typically in the form of liquid and can be added to the
concrete both at the time of mixing and before placing to
improve
various
concrete
properties
such
as
workability, air content and durability, etc. |
| CLOSELY SPACED
ANCHORAGES |
Anchorage devices are defined as closely spaced if their
centre to centre spacing does not exceed 1.5 times the
width of the anchorage devices in the direction
considered. |
| CLOSURE | A placement of cast-in-place concrete used to connect
two or more previously cast portions of a structure. |
| COMPOSITE
CONSTRUCTION | Concrete components or concrete and steel components
interconnected to respond to force effects as a unit. |
| COMPRESSION-
CONTROLLED
SECTION | A cross-section in which the net tensile strain in the
extreme tension steel at nominal resistance is less than
or equal to the compression-controlled strain limit. |
| COMPRESSION-
CONTROLLED
STRAIN LIMIT | The net tensile strain in the extreme tension steel at
balanced strain conditions. |
| CONCRETE
COVER | The specified minimum distance between the surface of
the reinforcing bars, strands, post-tensioning ducts,
anchorages, or other embedded items, and the surface of
the concrete. |
| CONFINEMENT | A condition where the disintegration of the concrete
under compression is prevented by the development of
lateral and/or circumferential forces such as may be
provided by appropriate reinforcing steel or composite
tubes, or similar devices. |
| CONFINEMENT
ANCHORAGE | Anchorage for a post-tensioning tendon that functions
on the basis of containment of the concrete in the
anchorage zone by special reinforcement. |
| CREEP | Time dependent deformation of concrete under
permanent load. |
| CREEP
COEFFICIENT | The ratio of creep strain to elastic strain in concrete. |
| CREEP IN
CONCRETE | Increase in strain with time in concrete subjected to
sustained stress. |
| CURVATURE
FRICTION | Friction resulting from bends or curves in the specified
prestressing tend stage at which the compressive
stresses on profile. |
| DAMAGE
CONTROL | A means to ensure that the limit state requirement is
met for restorability or reparability of a structure. |
| DECOMPRESSION | The stage at which the compressive stresses, induced
prestress, are overcome by the tensile stresses. |
| DEFORMABILITY | A term expressing the ability of concrete to deform. |
| DEGREE OF
DETERIORATION | The extent to which the performance of a structure is
degraded or the extent to which the deterioration has
progressed from the time of construction, as a result of
its exposure to the environment. |
| DESIGN LIFE | Assumed period for which the structure is to be used
satisfactorily for its intended purpose or function with
anticipated maintenance but without substantial repair
being necessary. |
| DETERIORATION
INDEX | An index selected for estimating and evaluating the
extent of the deterioration process. |
| DETERIORATION
PREDICTION | Prediction of the future rate of deterioration of a
structure based on results of inspection and relevant
records made during the design and construction stages. |
| DEVIATION
SADDLE | A concrete block build-out in web, flange, or web-flange
junction used to control the geometry of or to provide a
means for changing direction of, external tendons. |
| DRYING
SHRINKAGE | Volume decrease due to loss of moisture from concrete
in the hardened state which is usually serious in hot and
dry environment. |
| DURABILITY
DESIGN | Design to ensure that the structure can maintain its
required
functions
during
service
life
under
environmental actions. |
| DURABILITY
GRADE | The extent of durability to which the structure shall be
maintained in order to satisfy the required performance
during its design life. This affects the degree and
frequency of the remedial actions to be carried out
during that life. |
| DYNAMIC
APPROACH | An approach based on dynamic analysis to assess the
overall forces on a structure liable to have a resonant
response to wind action. |
| DYNAMIC
RESPONSE FACTOR | Factor to account for the effects of correlation and
resonant response. |
| EARLY AGE
STATE | The state of concrete from final setting until the
achievement of the required characteristic strength. |
| EFFECTIVE
PRESTRESS | Stress remaining in prestressing tendons after all losses
have occurred, excluding effects of dead load and
superimposed load. |
| ENVIRONMENTAL
ACTIONS | An assembly of physical, chemical or biological
influences which may cause deterioration to the
materials making up the structure, which in turn may
adversely affect its serviceability, restorability and
safety. |
| FATIGUE LOADS | Repetitive loads causing fatigue in the material which
reduces its strength, stiffness and deformability. |
| FINAL PRESTRESS | Stress which exists after substantially all losses have
occurred. |
| FINAL TENSION | The tension in the steel corresponding to the state of the
final prestress. |
| FORMWORK | Total system of support for freshly placed concrete
including the mould or sheathing, all supporting
members, hardware and necessary bracings. |
| FUNCTION | The task which a structure is required to perform. |
| GENERAL ZONE | Region adjacent to a post-tensioned anchorage within
which the prestressing force spreads out to an
essentially linear stress distribution over the cross
section of the component. |
| GROUT | A mixture of cementitious material and water with or
without admixtures. |
| INITIAL
PRESTRESS | The prestress in the concrete at transfer. |
| INITIAL TENSION | The maximum stress induced in the prestressing tendon
at the time of stressing operation. |
| JACKING FORCE | Temporary force exerted by device that introduces
tension into prestressing tendons. |
| LIMIT STATE | A critical state specified using a performance index,
beyond which the structure no longer satisfies the
design performance requirements. |
| LIMITS OF
DISPLACEMENT | Allowable deformation of structure in terms of such
parameters as inter-storey drift and relative horizontal
displacement, to control excessive deflection, cracking
and vibration. |
| LONG-TERM
PERFORMANCE
INDEX | Index defining the remaining capacity of a structure in
performing its design functions during the design life. |
| LOCAL ZONE | The volume of concrete that surrounds and is
immediately ahead of the anchorage device and that is
subjected to high compressive stresses. |
| MAINTENANCE | A set of activities taken to ensure that the structure
continues to perform its functions satisfactorily during
the design life. |
| MECHANICAL
FORCES | An assembly of concentrated or distributed forces acting
on a structure, or deformations imposed on it. |
| MODEL | Mathematical
description
or
experimental
setup
simulating the actions, material properties and behavior
of a structure. |
| MONITORING | Continuous recording of data pertaining to deterioration
and/or performance of structure using appropriate
equipment. |
| NOMINAL
STRENGTH OF
MATERIAL | The characteristic values of the strength of materials
used for calculation, in absence of the available
statistical data. |
| NORMAL
CONCRETE | Concrete which is commonly used in construction; it
does not include special constituent materials other than
Portland cement, water, fine aggregate, coarse aggregate
and common mineral and chemical admixtures; it does
not require any special practice for its manufacturing
and handling. |
| OVERALL
PERFORMANCE
INDEX | Index indicating the overall performance of the
structure. |
| PARTIAL
PERFORMANCE
INDEX | Index indicating a partial performance of the structure. |
| PARTIAL SAFETY
FACTOR FOR
MATERIAL | For analysis purposes, the design strength of a material
is determined as the characteristic strength divided by a
partial safety factor. |
| PERFORMANCE | Ability (or efficiency) of a structure to perform its design
functions. |
| PERFORMANCE
INDEX | Index indicating structural performance quantitatively. |
| PERMANENT
ACTIONS | Self-weights of structures inclusive of permanent
attachments, fixtures and fittings. |
| PLASTIC | Shrinkage arising from loss of water from the exposed |
| SHRINKAGE | surface of concrete during the plastic state, leading to
cracking at the exposed surface. |
| PLASTIC STATE | The state of concrete from just after placing until the
final setting of concrete. |
| POST-
TENSIONING | Method of prestressing in which tendons are tensioned
after concrete has hardened. |
| PRESTRESSED
CONCRETE | Reinforced concrete in which internal stresses have
been introduced to reduce potential tensile stresses in
concrete resulting from loads. |
| PRETENSIONING | Method of prestressing in which tendons are tensioned
before concrete is placed. |
| SHRINKAGE LOSS | The loss of stress in the prestressing steel resulting from
the shrinkage of concrete. |
| RELIABILITY | Ability of a structure to fulfill specified requirements
during its design life. |
| REMAINING | Period from the point of inspection to the time when the |
| SERVICE LIFE | structure is no longer useable, or does not satisfactorily
perform the functions determined at the time of design. |
| REMEDIAL ACTION | Maintenance action carried out with the objective of
arresting or slowing down the deterioration process,
restoring or improving the performance of a structure,
or reducing the danger of damage or injury to the users
or any third party. |
| REPAIR | Remedial action taken with the objective of arresting or
slowing down the deterioration of a structure, or
reducing the possibility of damage to the users or third
party. |
| RESTORABILITY | Ability of a structure to be repaired physically and
economically when damaged under the effects of
considered actions. Also known as REPAIRABILITY. |
| ROBUSTNESS | Ability of a structure to withstand damage by events like
fire, explosion, impact, instability or consequences of
human
errors.
Also
known
as
STRUCTURAL
INSENSITIVITY. |
| SAFETY | Ability of a structure to ensure that no harm would come
to the users and to people in the vicinity of the structure
under any action. |
| SERVICE LIFE | The length of time from the completion of a structure
until the time when it is no longer usable because of its
failure to adequately perform its design functions. |
| SERVICEABILITY | Ability of a structure to provide adequate services or
functionality in use under the effects of considered
actions. |
| SETTLEMENT OF
CONCRETE | Sinking of the concrete surface after placing due to
bleeding and/or escaping of the entrapped and
entrained air in the concrete. |
| SPECIAL
CONCRETE | Concrete other than normal concrete including light
weight concrete, roller compacted concrete, self-
compacting concrete, fiber-reinforced concrete, anti-
washout under water concrete, etc. |
| STIFF AND
FLEXIBLE
STRUCURES | Stiff structures refer to those that are not sensitive to
dynamic effects of wind, while flexible ones are those
that are sensitive to such effects. |
| STRENGTHENING | Remedial action applied to a structure with the objective
of restoring or improving its load bearing capacity to a
level which is equal to, or higher than, the original
design level. |
| STRESS AT
TRANSFER | The stress in both the prestressing tendon and the
concrete at the stage when the prestressing tendon is
released from the prestressing mechanism. |
| TEMPERATURE
CRACKING | Cracking caused by thermal stress which arises from
differential temperatures in the concrete mass. |
| TENDON | Steel element such as wire, cable, bar, rod, or strand, or a
bundle of such elements, used to impart prestress to
concrete. |
| THRESHOLD
LEVEL OF
PERFORMANCE | Minimum acceptable level of performance of a structure. |
| TRANSFER | Act of transferring stress in prestressing tendons from
jacks or pretensioning bed to concrete member. |
| TRANSFER
LENGTH | The distance required at the end of a pretensioned
tendon for developing the maximum tendon stress by
bond. |
| ULTIMATE LIMIT
STATE | Limit state for safety. |
| VARIABLE
ACTION | Action due to a moving object on the structure as well as
any load whose intensity is variable, including traffic
load, wave load, water pressure, and load induced by
temperature variation. |
| WOBBLE
FRICTION | Friction caused by unintended deviation of prestressing
sheath or duct from its specified profile. |
| WORKABILITY | The term expressing the ease with which concrete can
be placed, compacted and filled. |
### 9.3.2 Notation and Symbols
* $A$ = Area of the part of cross-section between flexural tension face and centre of gravity of gross section, mm2
* $A_{ch}$ = Cross-sectional area of a structural member measured to the outside edges of transverse reinforcement, mm2
* $A_g$ = Gross area of concrete section, mm2 . For a hollow section, $A_g$ is the area of the concrete only and does not include the area of the void(s)
* $A_{ps}$ = Area of prestressed reinforcement in tension zone, mm2
* $A_s$ = Area of nonprestressed tension reinforcement, mm2
* $A_s'$ = Area of compression reinforcement, mm2
* $C_c$ = Clear cover of reinforcement, mm
* $D$ = Dead loads, or related internal moments and forces
* $I$ = Moment of inertia of cross-section resisting externally applied factored loads, mm4
* $I_{cr}$ = Moment of inertia of cracked section transformed to concrete, mm4, Sec 6.
* $I_g$ = Moment of inertia of gross concrete section about centroidal axis, neglecting reinforcement, mm4
* $I_e$ = Effective moment of inertia for computation of deflection, mm4
* $K$ = Wobble friction coefficient per meter of prestressing tendon
* $L$ = Live loads, or related internal moments and forces
* $M_a$ = Maximum moment in member due to service loads at stage deflection is computed, N-mm
* $M_{cr}$ = Moment causing flexural cracking at section due to externally applied loads, N-mm
* $M_{max}$ = Maximum factored moment at section due to externally applied loads, N-mm
* $M_u$ = Factored moment at section, N-mm
* $N_c$ = Tensile force in concrete due to unfactored dead load plus live load (D + L), N
* $P_j$ = Prestressing tendon force at jacking end, N
* $PI_P$ = Inherent or possessed performance index
* $PI_R$ = Inherent or possessed performance index
* $P_x$ = Prestressing tendon force at any point x
* $V_c$ = Nominal shear strength provided by concrete, N
* $V_{ci}$ = Nominal shear strength provided by concrete when diagonal cracking results from combined shear and moment, N
* $V_{cw}$ = Nominal shear strength provided by concrete when diagonal cracking results from excessive principal tensile stress in web, N
* $V_d$ = Shear force at section due to unfactored dead load, N
* $V_i$ = Factored shear force at section due to externally applied loads occurring simultaneously with $M_{max}$, N
* $V_n$ = Nominal shear strength, N
* $V_p$ = Vertical component of effective prestress force at section, N
* $V_s$ = Nominal shear strength provided by shear reinforcement, N
* $V_u$ = Factored shear force at section, N
* $X$ = Shorter overall dimension of rectangular part of cross-section
* $a$ = Depth of equivalent rectangular stress block, mm
* $b$ = Width of compression face of member, mm
* $d$ = Distance from extreme compression fiber to centroid of nonprestressed tension reinforcement, mm
* $d'$ = Distance from extreme compression fiber to centroid of compression reinforcement, mm
* $d_b$ = Nominal diameter of bar, wire, or prestressing strand, mm
* $d_p$ = Distance from extreme compression fiber to centroid of prestressed reinforcement, mm
* $e$ = Base of Napierian logarithm
* $f_c'$ = Specified compressive strength of concrete, N/mm2
* $f_{ci}'$ = Compressive strength of concrete at transfer of prestress, N/mm2
* $f_d$ = Stress due to unfactored dead load, at extreme fiber of section where tensile stress is caused by externally applied loads, N/mm2
* $f_{pe}$ = Compressive stress in concrete due to effective prestress forces only (after allowance for all prestress losses) at extreme fiber of section where tensile stress is caused by externally applied loads, N/mm2
* $f_{pc}$ = Average compressive stress in concrete due to effective prestress force only (after allowance for all prestress losses), N/mm2
* $f_{ps}$ = Stress in prestressed reinforcement at nominal strength, N/mm2
* $f_{pu}$ = Specified tensile strength of prestressing tendons, N/mm2
* $f_{py}$ = Specified yield strength of prestressing tendons, N/mm2
* $f_r$ = Modulus of rupture of concrete, N/mm2
* $f_{se}$ = Effective stress in prestressed reinforcement (after allowance for all prestress losses), N/mm2
* $f_t$ = Extreme fiber stress in tension in the pre-compressed tensile zone calculated at service loads using gross section properties, N/mm2 (MPa)
* $f_y$ = Specified yield strength of nonprestressed reinforcement, N/mm2
* $f_{yt}$ = Specified yield strength of transverse reinforcement, N/mm2
* $h$ = Overall thickness of member, mm
* $h_f$ = Overall thickness of flange of flanged section, mm
* $l$ = Length of span of two-way flat plates in direction parallel to that of the reinforcement being determined, mm
* $l_x$ = Length of prestressing tendon element from jacking end to any point x, metre
* $s$ = Spacing of shear or torsion reinforcement in direction parallel to longitudinal reinforcement, mm
* $y$ = Longer overall dimension of rectangular part of cross-section
* $y_t$ = Distance from centroidal axis of gross section, neglecting reinforcement, to extreme fibre in tension
* $\alpha$ = Total angular change of prestressing tendon profile in radians from tendon jacking end to a point x
* $\beta_1$ = Factor relating depth of equivalent rectangular compressive stress block to neutral axis depth
* $\gamma_p$ = A factor for type of prestressing steel
* $\mu$ = Curvature friction coefficient
* $\lambda$ = Modification factor reflecting the reduced mechanical properties of lightweight concrete, all relative to normal weight concrete of the same compressive strength (i.e., $\lambda$ = 1.0 for normal weight concrete and 0.75 for all lightweight concrete. Else, $\lambda$ shall be determined based on volumetric proportions of lightweight and normal weight aggregates, but shall not exceed 0.85.)
* $\rho$ = Ratio of nonprestressed tension reinforcement = $A_s/(bd)$
* $\rho'$ = Ratio of compression reinforcement = $A_s'/(bd)$
* $\rho_p$ = Ratio of prestressed reinforcement = $A_{ps}/(bd_p)$
* $\phi$ = Strength reduction factor
* $\omega$ = $\rho f_y / f_c'$
* $\omega'$ = $\rho' f_y / f_c'$
* $\omega_p$ = $\rho_p f_{ps} / f_c'$
* $\omega_p, \alpha_{p\omega}, \omega_w$ = Reinforcement indices for flanged sections computed for $\omega$, $\omega_p$ and $\omega'$ except that $b$ shall be the web width, and reinforcement area shall be that required to develop compressive strength of web only.
For other symbols and units of quantities, reference may be made to Chapter 6.
## 9.4 Analysis and Design
### 9.4.1 General
#### 9.4.1.1
Prestressed members shall be designed for adequate strength in accordance with the provisions of this Chapter.
#### 9.4.1.2
Unless specifically excluded or superseded by the provisions of this Chapter, all other relevant provisions of this Code shall apply to prestressed concrete.
#### 9.4.1.3
Design of prestressed members shall be based on strength and on the behavior at service conditions at all stages that will be critical during the life of the structure from the time prestress is first applied.
#### 9.4.1.4
Stress concentrations due to prestressing shall be considered in design.
#### 9.4.1.5
Provisions shall be made for effects on adjoining construction of elastic and plastic deformations, deflections, changes in length and rotations due to prestressing. Effects of creep, temperature and shrinkage shall also be considered.
#### 9.4.1.6
The possibility of buckling in a member between points where there is intermittent contact between prestressing steel and an oversized duct and buckling in thin webs and flanges shall be considered.
#### 9.4.1.7
In computing section properties before bonding of prestressing steel, effect of loss of area due to open ducts shall be considered.
#### 9.4.1.8
Thermal gradient and differential shrinkage shall be considered in composite construction using prestressed concrete members.
#### 9.4.1.9
In evaluating the slenderness effects during lifting of slender beams, consideration shall be given to beam geometry, location of lifting points, method of lifting and tolerances in construction. All beams which are lifted on vertical or inclined slings shall be checked for lateral stability and lateral moment on account of tilting of beam. Reference may be made to specialist literature in this regard.
### 9.4.2 Design Assumptions
#### 9.4.2.1
Strength design of prestressed members for flexure and axial loads shall be based on assumptions given in Sections 9.4.2.2 to 9.4.2.7 and shall satisfy the applicable conditions of equilibrium and compatibility of strains.
#### 9.4.2.2
Strains in steel and concrete shall be assumed to be directly proportional to the distance from the neutral axis except for Deep Beams.
#### 9.4.2.3
If nonprestressed reinforcement conforming to Sec 5.3.2 is used then, stress in such reinforcements below $f_y$, shall be taken as $E_s$ times steel strain. For strains greater than that corresponding to $f_y$, stress in reinforcement shall be considered independent of strain and equal to $f_y$.
#### 9.4.2.4
Maximum usable strain at extreme concrete compression fiber shall be assumed equal to 0.003.
#### 9.4.2.5
The relationship between concrete compressive stress distribution and concrete strain shall be assumed to be rectangular, trapezoidal, parabolic, or any other shape that results in prediction of strength in substantial agreement with results of comprehensive tests
#### 9.4.2.6
Requirements of Sec 9.4.2.5 are satisfied by an equivalent rectangular concrete stress distribution defined by the following:
* (a) Concrete stress of $0.85f_c'$ shall be assumed uniformly distributed over an equivalent compression zone bounded by edges of the cross section and a straight line located parallel to the neutral axis at a distance $a = \beta_1c$ from the fiber of maximum compressive strain.
* (b) Distance from the fiber of maximum strain to the neutral axis, $c$ is measured in a direction perpendicular to the neutral axis.
* (c) For $f_c'$ between 17.5 and 28 MPa, $\beta_1$ shall be taken as 0.85. For $f_c'$ above 28 MPa, $\beta_1$ shall be reduced linearly at a rate of 0.05 for each 7 MPa of strength in excess of 28 MPa, but $\beta_1$ shall not be taken less than 0.65.
#### 9.4.2.7
For investigation of stresses at transfer of prestress, at service loads, and at cracking loads, elastic theory shall be used with the following assumptions:
* (i) Strains vary linearly with depth through the entire load range.
* (ii) At cracked sections, concrete resists no tension.
### 9.4.3 Classification of Prestressed Concrete Members
Prestressed concrete flexural members shall be classified as Class U (uncracked), Class T (transition) and Class C (cracked) based on $f_t$, the computed extreme fiber stress in tension in the pre-compressed tensile zone calculated at service load as follows:
* (a) Class U: $f_t \leq 0.62\sqrt{f_c'}$
* (b) Class T: $0.62\sqrt{f_c'} \leq f_t \leq 1.0\sqrt{f_c'}$
* (c) Class C: $f_t > 1.0\sqrt{f_c'}$
Prestressed two-way slab systems shall be designed as class U with $f_t \leq 0.50\sqrt{f_c'}$
### 9.4.4 Shapes of Beams and Girders
For prestressed concrete non-composite beams/girders, the frequently used shapes are:
* (a) Symmetrical I-section,
* (b) Unsymmetrical I-section,
* (c) T-section,
* (d) Inverted T-section,
* (e) Box section and
* (f) Solid/hollow rectangular section.
Commentary:
The suitability of selecting a particular shape will depend on the specific design requirement and economy of construction. In general, T or equal or unequal I- section are common choices to achieve economy in steel and concrete. Due consideration to the simplicity of formwork is also required.
### 9.4.5 Material Properties for Design
#### 9.4.5.1
Concrete Preparation and Design: Concrete shall be prepared, conveyed, placed/cast, cured, tested and maintained following appropriate sections of Chapter 5 of the Code. Relevant applicable standards are mentioned in Chapter 5 and also listed in Table 6.9.9. Unless specifically applicable to prestressed concrete, general design requirements of normal concrete are those of Chapter 6 of the Code.
#### 9.4.5.2
Class: The Class of concrete is defined by the specified strength of concrete cylinder $f_c'$ at 28 days. For example, Class 20 indicates concrete cylinder crushing strength of $f_c' = 20$ N/mm2 . Commonly, the classes of concrete shall be in steps of 5 N/mm2 as given by: Class 20, 25, 30 35… … … … 65 and 70 etc. although concrete in between these classes may also be permitted (like class 21, 24, 28, 31, 38, 42, and 49 etc.).
#### 9.4.5.3
Modulus of Elasticity, $E_c$: Modulus of elasticity, $E_c$ for concrete shall be permitted to be taken as $w_c^{1.5} 0.043\sqrt{f_c'}$ (in N/mm2 ) for values of $w_c$ between 1440 and 2560 kg/m3 . For normal weight concrete, $E_c$ may be permitted to be taken as $4700\sqrt{f_c'}$.
#### 9.4.5.4
Modulus of Rupture, $f_r$: Modulus of rupture, $f_r$ for concrete shall be permitted to be taken as $0.62\lambda\sqrt{f_c'}$ where $\lambda = 1$ for normal weight concrete and 0.75 for all lightweight concrete.
#### 9.4.5.5
Reinforcing steel: Appropriate applicable standards for reinforcing steel are given in Chapter 5 and also listed in Table 6.9.10. Unless specifically applicable to prestressed concrete, general design requirements of reinforcing steel are those that has been laid down in Chapter 6 of the Code.
#### 9.4.5.6
Modulus of elasticity, $E_s$: Where it is not possible to ascertain the modulus of elasticity of reinforcing steel by test and from the manufacturer of steel, the modulus of elasticity of reinforcing steel may be permitted to be taken as $E_s = 200,000$ N/mm2 .
#### 9.4.5.7
Prestressing Steel: Appropriate applicable standards for prestressing steel are listed in Table 6.9.11.
#### 9.4.5.8
Modulus of elasticity, $E_s$: Where it is not possible to ascertain the modulus of elasticity of pain/ indented steel wire and prestressing steel (bar or strand) by test and from the manufacturer of steel, the values of $E_s$ given in Table 6.9.1 may be used:
Table 6.9.1: Modulus of Elasticity of Prestressing Steel and Cold Drawn Wire
| Type of steel | Modulus of elasticity, Es(kN/mm2) |
| ---------------------------------------------- | -------------------------------------------- |
| Plain/indented cold-drawn wire | 200 |
| High tensile steel bars rolled or heat-treated | 205 |
| Strands | 195 |
## 9.5 Serviceability Requirements – Flexural Members
### 9.5.1 Stress in Concrete At Transfer
Stresses in concrete immediately after prestress transfer (before timedependent prestress losses occur) are as follows:
* (a) Extreme fiber stress in compression except as permitted in (b) shall not exceed $0.60f_{ci}'$
* (b) Extreme fiber stress in compression at ends of simply support members shall not exceed $0.70f_{ci}'$
* (c) Where computed concrete tensile strength, $f_t$ exceeds $0.5\sqrt{f_c'}$ at ends of simply supported members, or $0.25\sqrt{f_c'}$ at other locations, additional bonded reinforcement shall be provided in the tensile zone to resist the total tensile force in concrete computed with the assumption of an uncracked section.
**Allowable stresses in concrete**
For Class U and Class T prestressed flexural members, stresses in concrete at service loads (based on uncracked section properties and after allowance for all prestress losses) shall not exceed the following:
* (a) Extreme fiber stress in compression due to prestress plus $0.45f_c'$ sustained load
* (b) Extreme fiber stress in compression due to prestress $0.60f_c'$ plus total load
### 9.5.2
Permissible stresses in Sections 9.5.1 and 9.5.2 shall be permitted to be exceeded if shown by test or analysis that performance will not be impaired.
### 9.5.3 Reinforcement Spacing
#### 9.5.3.1
For Class C prestressed flexural members not subject to fatigue or to aggressive exposure, the spacing $s$ of bonded reinforcement nearest the extreme tension face shall not exceed that for normal Reinforced Concrete, as given below:
$$
s = 380(280/f_s) - 2.5C_c \tag{6.9.1}
$$
But, not greater than $300(280/f_s)$, where $C_c$ is the least distance from the surface of reinforcement or prestressing steel to the tension face. If there is only one bar or wire nearest to the extreme tension face, $s$ used in the above equation is the width of the extreme tension face.
Calculated stress $f_s$ in reinforcement closest to the tension face at service loads shall be computed based on the unfactored moment. It shall be permitted to take $f_s$ as $\frac{2}{3} f_y$.
For structures subject to fatigue or exposed to corrosive environments, investigations, judgment and precautions are required.
#### 9.5.3.2
The spacing requirements Sec 9.5.3.1 shall be met by nonprestressed reinforcement and bonded tendons.
* (a) The spacing of bonded tendons shall not exceed 2/3rd of the maximum spacing permitted for nonprestressed reinforcement.
* Where both reinforcement and bonded tendons are used to meet the spacing requirement, the spacing between a bar and a tendon shall not exceed 5/6th of that permitted by 9.5.3.1. See also (c) below.
* (b) In applying Eq. 6.9.1 to prestressing tendons, $\Delta f_{ps}$ shall be substituted for $f_s$, where $\Delta f_{ps}$ shall be taken as the calculated stress in the prestressing steel at service loads based on a cracked section analysis minus the decompression stress $f_{dc}$. It shall be permitted to take $f_{dc}$ equal to the effective stress in the prestressing steel $f_{se}$. See also (c) below.
* (c) In applying Eq. 6.9.1 to prestressing tendons, the magnitude of $\Delta f_{ps}$ shall not exceed 250 N/mm2 . When $\Delta f_{ps}$ is less than or equal to 140 N/mm2 , the spacing requirements of Sec 9.5.3.2(a) and (b) shall not apply.
* (d) Where depth $h$ of a beam exceeds 900 mm, the area of longitudinal skin reinforcement consisting of untensioned reinforcing steel or bonded tendons shall be uniformly distributed along both side faces of the member as required by Sec 6.3.6.7. The spacing $s$ shall be determined using Sections 9.5.3.1 and 9.5.3.2 (a), (b) and (c). It shall be permitted to include such reinforcement in strength computations if a strain compatibility analysis is made to determine stress in the individual bars or wires.
### 9.5.4 Permissible Stresses in Prestressing Steel
Tensile stress in prestressing tendons shall not exceed the following:
* (a) Due to prestressing steel jacking force $0.94f_{py}$ but not greater than the lesser of $0.80f_{pu}$ and the maximum value recommended by the manufacturer of prestressing steel or anchorage devices.
* (b) Immediately after prestress transfer $0.82f_{py}$ but not greater than $0.74f_{pu}$.
* (c) Post-tensioning tendons, at anchorage devices and couplers, immediately after force transfer $0.70f_{pu}$
## 9.6 Losses of Prestress
Effective stress in prestressing steel is usually subject to different losses at different stages. Superimposed loads can result in gain of prestress due to bending of the member which shall be taken into consideration if significant. To determine effective stress in the prestressing steel, !, allowance for the following sources of loss of prestress shall be considered:
### 9.6.1 Immediate Losses
* (a) Loss due to elastic shortening of concrete;
* (b) Loss due to prestressing steel seating at transfer (Anchorage slip);
* (c) Loss due to friction (for post-tensioned concrete only).
### 9.6.2 Long-term Losses
* (a) Loss due to relaxation of prestressing steel stress;
* (b) Loss due to creep of concrete;
* (c) Loss due to shrinkage of concrete.
Unless otherwise determined by actual tests, allowance for these losses shall be made in accordance with the provisions of Sections 9.6.3 to 9.6.8.
### 9.6.3 Loss due to Elastic Shortening of Concrete
* (a) The loss of prestress due to immediate elastic shortening of adjacent concrete upon transfer of initial prestress shall be calculated as specified in this section. For pretensioning, the loss of prestress in the tendons at transfer shall be calculated on a modular ratio basis using the stress in the adjacent concrete.
* (b) For members with post-tensioned tendons which are not stressed simultaneously, there is a progressive loss of prestress during transfer due to the gradual application of the prestressing forces. This loss of prestress shall be calculated on the basis of half the product of the stress in the concrete adjacent to the tendons averaged along their lengths and the modular ratio. Alternatively, the loss of prestress may be exactly computed based on the sequence of tensioning.
### 9.6.4 Loss due to Prestressing Steel Seating at Transfer (Anchorage Slip)
* (a) Any loss of prestress which may occur due to slip of wire or strand during anchoring or due to straining of the anchorage shall be allowed for in the design.
* (b) Necessary additional elongation may be provided for at the time of tensioning to compensate for this loss.
### 9.6.5 Loss due to Relaxation of Prestressing Steel Stress
* (a) The relaxation losses in prestressing steel shall be determined from experiments. When experimental values are not available, the relaxation losses, considering normal relaxation steel, may be assumed as given in Table 6.9.2.
Table 6.9.2: Relaxation Losses for Prestressing Steel at 1000 Hours at 27o C
| Initial Stress | Relaxation Loss N/mm2 |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------ | -------------------------------- |
| 0.5\k | 0 |
| 0.6\k | 35 |
| 0.7\k | 70 |
| 0.8\k | 90 |
| For tendons at higher temperature or subject to large lateral loads, greater relaxation losses may be allowed, subject to the advice of the metallurgy specialist. | |
* (b) No reduction in the value of the relaxation losses should be made for a tendon with a load equal to or greater than the relevant jacking force that has been applied for a short duration prior to the anchoring of the tendon.
### 9.6.6 Loss due to Creep of Concrete
* (a) Creep occurs due to superimposed permanent dead load added to the member after it has been prestressed. Creep of concrete may be assumed to be proportional to the stress provided the stress in concrete does not exceed 40 percent of its compressive strength.
* (b) In the absence of test data, the ultimate creep strain may be estimated from the following values of creep coefficient, which is the ratio of the ultimate creep strain to the elastic strain at the age of loading. Table 6.9.3 shows the values at different days.
Table 6.9.3: Creep Coefficient of Concrete
| Age at Loading | Creep coefficient |
| -------------- | ----------------- |
| 7 days | 2.2 |
| 28 days | 1.6 |
| 1 year | 1.1 |
* (c) The ultimate creep strain estimated as above does not include the elastic strain. For the calculation of deformation at some stage before the total creep is reached, it may be assumed that 50 percent of the total creep takes place in the first month after loading and about 75 percent of the total creep takes place in the first six months after loading. For post-tensioning the creep coefficients shall be taken as 80% of those given here.
* (d) The loss of prestress due to creep of concrete shall be determined for all the permanently applied loads including the prestress. Loss due to stresses of short duration including live load and erection stresses may be ignored.
* (e) The loss of prestress due to creep of concrete shall be obtained as the product of the modulus of elasticity of the prestressing steel and the ultimate creep strain of the concrete fiber integrated along the centre-line of the prestressing steel over its entire length.
* (f) The total creep strain during any specific period shall be assumed to be the creep strain due to sustained stress equal to the average of the stresses at the beginning and end of the period.
### 9.6.7 Loss due to Shrinkage of Concrete
* (a) In the absence of test data, the approximate value of shrinkage strain in concrete for design purposes shall be assumed as follows:
* For pretensioning : 0.0003
* For post-tensioning : $0.0002/[\log_{10}(t + 2)]$
Where, t = age of concrete at transfer in days.
Other standard procedures like AASHTO LRFD Specifications may be used.
* (b) For the calculation of deformation of concrete at some stage before the maximum shrinkage occurs it may be assumed that 50 percent of the shrinkage takes place during the first month and about 75 percent of the shrinkage takes place in the first six months after drying of concrete starts.
* (c) The loss of prestress due to shrinkage of concrete shall be obtained as the product of the modulus of elasticity of steel and the shrinkage strain of concrete.
### 9.6.8 Loss due to Friction (For Post-tensioned Tendons Only)
* (a) The design shall take into consideration all losses in prestress that may occur during tensioning due to friction between the posttensioning tendons and the surrounding concrete or any fixture attached to the steel or concrete.
* (b) The value of prestressing force $P_x$ at a distance $l_x$ metre from the jacking end and acting in the direction of the tangent to the curve of the cable shall be calculated from the relation:
$$
P_x = P_j e^{-(Kl_x + \mu\alpha)} \tag{6.9.2}
$$
When $(Kl_x + \mu\alpha)$ is greater than 0.3, $P_x$ may be computed from
$$
P_x = \frac{P_j}{1 + Kl_x + \mu\alpha} \tag{6.9.3}
$$
For use in Equations 6.9.2 and 6.9.3, the values of wobble friction coefficient $K$ and curvature friction coefficient $\mu$ shall be experimentally determined or obtained from the tendon manufacturer, and verified during tendon stressing operations.
* (c) Values of $K$ and $\mu$ used in the design shall be shown on design drawings
* (d) In absence of test results or manufacturer's recommendation, the following values of $\mu$ and $K$ shown in Table 6.9.4 may be taken as a guide:
Table 6.9.4: Friction Coefficients (K and µ) for Post-Tensioned Tendons
| | Types of Te | ndons | Coefficient,
Kper meter | Curvature coefficient,
µper radian |
| -------------------- | ------------------------ | ----------------------------------------- | -------------------------------- | --------------------------------------- |
| Grouted
metal s | Tendons in
heathing | Wire tendons
High-strength
bars | 0.0033-0.0049
0.0003-0.0020 | 0.15-0.25
0.08-0.30 |
| | | 7-wire strand | 0.0016-0.0066 | 0.15-0.25 |
| Unbonded | Mastic | Wire tendons | 0.0033-0.0066 | 0.05-0.15 |
| tendons | coated | 7-wire strand | 0.0033-0.0066 | 0.05-0.15 |
| | Pre-greased | Wire tendons | 0.001-0.0066 | 0.05-0.15 |
| | | 7-wire strand | 0.001-0.0066 | 0.05-0.15 |
### 9.6.9
Values of wobble and curvature friction coefficients used in design shall be shown on design drawings.
### 9.6.10
The effect of reverse friction shall be taken into consideration in such cases where the initial tension applied to a prestressing tendon is partially released (e.g., anchorage slip) and action of friction in the reverse direction causes significant alteration in the distribution of stress along the length of the tendon.
### 9.6.11
Where loss of prestress in a member occurs due to connection of member to adjoining construction, such loss of prestress shall be allowed for in design.
## 9.7 Control of Deflection
### 9.7.1
For prestressed concrete flexural members, designed in accordance with the provisions of this Chapter, immediate deflection shall be computed by usual methods or formulas for elastic deflections, and the moment of inertia of gross concrete section,*I* *g*, shall be permitted to be used for Class U flexural members.
### 9.7.2
For Class C and Class T flexural members, deflection calculations shall be based on cracked transformed section analysis. It shall be permitted to base calculations on an effective moment of inertia, $I_e$ as given in Eq. 6.9.4a.
$$
I_e = \left(\frac{M_{cr}}{M_a}\right)^3I_g + \left[1-\left(\frac{M_{cr}}{M_a}\right)^3\right]I_{cr} \tag{6.9.4a}
$$
$$
M_{cr} = \frac{f_rI_g}{y_t} \tag{6.9.4b}
$$
$$
f_r = 0.62\lambda\sqrt{f_c'} \tag{6.9.4c}
$$
Deflection computed in accordance with Sec 9.7.1 shall not exceed the limits stipulated in Table 6.6.2, Chapter 6.
### 9.7.3
Additional long-term deflection of prestressed concrete members shall be computed taking into account stresses in concrete and steel under sustained load and including effects of creep and shrinkage of concrete and relaxation of steel.
## 9.8 Flexural Strength
### 9.8.1
Design moment strength of flexural members shall be computed by the strength methods of the Code. For prestressing steel, *f ps* shall be substituted for*f* *y*in strength computations.
### 9.8.2
As an alternative to a more accurate determination of $f_{ps}$ based on strain compatibility, the following approximate values of $f_{ps}$ shall be permitted to be used if $f_{se}$ is not less than $0.5f_{pu}$.
* (a) For members with bonded tendons
$$
f_{ps} = f_{pu}\left[1 - \frac{\gamma_p}{\beta_1}\left\{\rho_p \frac{f_{pu}}{f_c'} + \frac{d}{d_p}(\omega - \omega')\right\}\right] \tag{6.9.5}
$$
Where, $\omega = \dfrac{\rho f_y}{f_c'}$, $\omega' = \dfrac{\rho' f_y}{f_c'}$ and $\gamma_p$ is 0.55 for $f_{py}/f_{pu}$ not less than 0.80; 0.40 for $f_{py}/f_{pu}$ not less than 0.85; and 0.28 for $f_{py}/f_{pu}$ not less than 0.90.
If any compression reinforcement is taken into account when calculating $f_{ps}$ by Eq. 6.9.5:
The term $\left[\rho_p \dfrac{f_{pu}}{f_c'} + \dfrac{d}{d_p}(\omega - \omega')\right]$ shall be taken not less than 0.17 and d' shall be no greater than 0.15dp.
* (b) For members with unbonded tendons and with a span-to-depth ratio of 35 or less:
$$
f_{ps} = f_{se} + 70 + \frac{f_c'}{100\rho_p} \tag{6.9.6}
$$
* But $f_{ps}$ in Eq. 6.9.6 shall not be taken greater than the lesser of $f_{py}$ and $(f_{se} + 420)$.
* (c) For members with unbonded tendons and with a span-to-depth ratio greater than 35:
$$
f_{ps} = f_{se} + 70 + \frac{f_c'}{300\rho_p} \tag{6.9.7}
$$
But, $f_{ps}$ in Eq. 6.9.7 shall not be taken greater than the lesser of $f_{py}$ and $(f_{se} + 210)$
### 9.8.3
Non prestressed reinforcement conforming to Sec 5.3 Chapter 5 of this Part, if used with prestressing steel, shall be permitted to be considered to contribute to the tensile force and to be included in moment strength computations at a stress equal to $f_y$. Other non prestressed reinforcement shall
be permitted to be included in strength computations only if a strain compatibility analysis is performed to determine stresses in such reinforcement.
## 9.9 Limits For Flexural Reinforcement
### 9.9.1
Prestressed concrete sections shall be classified as either tensioncontrolled, transition, or compression-controlled sections, in accordance with a. and b. below.
* (a) Sections are compression-controlled if the net tensile strain in the extreme tension fiber $\varepsilon_t$, is equal to or less than the compressioncontrolled strain limit when the concrete in compression reaches its assumed strain limit of 0.003. The compression-controlled strain limit is the net tensile strain in the reinforcement at balanced strain conditions. For Grade 420 reinforcement, and for all prestressed reinforcement, it shall be permitted to set the compressioncontrolled strain limit to 0.002.
* (b) Sections are tension-controlled if the net tensile strain in the extreme tension steel, $\varepsilon_t$, is equal to or greater than 0.005 when the concrete in compression reaches its assumed strain limit of 0.003. Sections with $\varepsilon_t$ between the compression-controlled strain limit and 0.005 constitute a transition region between compression-controlled and tension-controlled sections. Appropriate strength reduction factor, $\phi$, from
Sec 9.9.2 shall apply.
### 9.9.2
The appropriate strength reduction factor, $\phi$, shall apply as given in (a) to (f) below.
* (a) Tension-controlled sections: 0.90
* (b) For compression-controlled sections
* (i) Members with spiral reinforcement as defined in Sec 6.2.3.2.2: 0.75
* (ii) Other reinforced members: 0.65
* (c) Shear and torsion: 0.75
* (d) Post-tensioned anchorage zones: 0.85
* (e) Strut and tie models: 0.75
* (f) Flexural sections in pre-tensioned members where strand embedment length is less than the development length
* (i) From the end of the member to the end of the transfer length: 0.75
* (ii) From the end of transfer length to the end of the development length, $\phi$ shall be taken as 0.75 to 0.90
Where bonding of the strand does not extend to the end of the member, strand embedment shall be assumed to begin at the end of the debonded length.
### 9.9.3
Total amount of prestressed and non-prestressed reinforcement in members with bonded prestressed reinforcement shall be adequate to develop a factored load at least 1.2 times the cracking load computed on the basis of the modulus of rupture*f* *c* , as given in Sec 9.4.5.4. This provision shall be permitted to be waived for flexural members with shear and flexural strength at least twice the required strength (U) calculated for the factored loads and forces in such combinations as are stipulated in Chapter 2, Loads.
### 9.9.4 Minimum Bonded Reinforcement
#### 9.9.4.1
A minimum area of bonded reinforcement shall be provided in all flexural members with unbonded tendons as required by Sections 9.9.4.2 and 9.9.4.3.
#### 9.9.4.2
Except as provided in Sec 9.9.4.3, minimum area of bonded reinforcement shall be computed by
$$
A_s = 0.004A_{ct} \tag{6.9.8}
$$
Where, $A_{ct}$ is area of that part of cross-section between the flexural tension face and center of gravity of gross-section.
* (a) Bonded reinforcement required by Eq. 6.9.8 shall be uniformly distributed over pre-compressed tensile zone as close as practicable to extreme tension fibre.
* (b) Bonded reinforcement shall be required regardless of service load stress conditions.
#### 9.9.4.3
For two-way flat slab systems, minimum area and distribution of bonded reinforcement shall be as required in (a), (b) and (c) below.
* (a) Bonded reinforcement shall not be required in positive moment areas where $f_t$, the extreme fibre stress in tension in the precompressed tensile zone at service loads (after allowance for all prestress losses), does not exceed $0.17\sqrt{f_c'}$.
* (b) In positive moment areas where computed tensile stress in concrete at service load exceeds $0.17\sqrt{f_c'}$ minimum area of bonded reinforcement shall be computed by
$$
A_s = \frac{N_c}{0.5f_y} \tag{6.9.9}
$$
Where, the value of $f_y$ used in Eq. 6.9.9 shall not exceed 420 MPa. Bonded reinforcement shall be uniformly distributed over precompressed tensile zone as close as practicable to the extreme tension fibre.
* (c) In negative moment areas at column supports, the minimum area of bonded reinforcement As in the top of the slab in each direction shall be computed by
$$
A_s = 0.00075A_g \tag{6.9.10}
$$
Where, $A_g$ is the larger gross cross-sectional area of the slab-beam strips in two orthogonal equivalent frames intersecting at a column in a two-way slab.
#### 9.9.4.4
Bonded reinforcement required by Eq. 6.9.10 shall be distributed between lines that are $1.5h$ outside opposite faces of the column support. At least four bars or wires shall be provided in each direction. Spacing of bonded reinforcement shall not exceed 300 mm.
#### 9.9.4.5
Minimum length of bonded reinforcement required by Sections 9.9.4.2 and 9.9.4.3 shall be as required in Sec 9.9.4.5 (a), (b) and (c).
* (a) In positive moment areas, minimum length of bonded reinforcement shall be one-third the clear span length, $l_n$ and centered in positive moment area.
* (b) In negative moment areas, bonded reinforcement shall extend one-sixth the clear span, $l_n$ on each side of support.
* (c) Where bonded reinforcement is provided for $\phi M_n$ in accordance with Sec 9.8.3 or for tensile stress conditions as per Sec 9.9.4.3 (b), minimum length also shall conform to provisions of Chapter 6.
## 9.10 Statically Indeterminate Structures
### 9.10.1
Frames and continuous construction of prestressed concrete shall be designed for satisfactory performance at service load conditions and for adequate strength.
### 9.10.2
Performance at service load conditions shall be determined by elastic analysis, considering reactions, moments, shears, and axial forces induced by prestressing, creep, shrinkage, temperature change, axial deformation, restraint of attached structural elements, and foundation settlement.
### 9.10.3
Moments used to compute required strength shall be the sum of the moments due to reactions induced by prestressing (with a load factor of 1.0) and the moments due to factored loads. Adjustment of the sum of these moments shall be permitted as allowed in Sec 9.10.4.
### 9.10.4
Redistribution of moments in continuous prestressed flexural members shall be:
* (a) Where bonded reinforcement is provided at supports in accordance with Sec 9.9.4, it shall be permitted to decrease negative or positive moments calculated by elastic theory for any assumed loading, in accordance with Sec 9.10.4 (b) and (c) below.
* (b) Except where approximate values for moments are used, it shall be permitted to decrease factored moments calculated by elastic theory at sections of maximum negative or maximum positive moment in any span of continuous flexural members for any assumed loading arrangement by not more than 1000 percent, with a maximum of 20 percent.
* (c) Redistribution of moment shall be made only when is equal to or greater than 0.0075 at the section at which moment is reduced.
### 9.10.5
The reduced moment shall be used for calculating redistributed moments at all other sections within the spans. Static equilibrium shall be maintained after redistribution of moments for each loading arrangement.
## 9.11 Compression Members - Combined Flexure And Axial Load
### 9.11.1 Prestressed Concrete Members Subject to Combined Flexure and Axial Load
With or without non-prestressed reinforcement, Prestressed concrete members subject to combined flexure and axial load shall be proportioned by the strength design methods of this Code. Effects of prestress, creep, shrinkage, and temperature change shall be included.
### 9.11.2 Limits for Reinforcement of Prestressed Compression Members
#### 9.11.2.1
Members with average compressive stress in concrete less than 1.6 N/mm2 , due to effective prestress force only, shall have minimum reinforcement in accordance with Sections 6.3.9.1, 6.3.9.2 for columns and Sec 6.6.3 for walls and minimum transverse reinforcement for compression members of Chapter 6.
#### 9.11.2.2
Except for walls, members with average compressive stress in concrete due to effective prestress force only, equal to or greater than 1.6 N/mm2 shall have all tendons enclosed by spirals or lateral ties in accordance with (a) through (d).
* (a) Spirals shall conform to the spiral reinforcement requirement for compression members of this Code and Sec 9.11.3.
* (b) Lateral ties shall be at least No. 10 in size or welded wire reinforcement of equivalent area, and shall be spaced vertically not to exceed 48 tie bar or wire diameters, or the least dimension of the compression member.
* (c) Ties shall be located vertically not more than half a tie spacing above top of footing or slab in any story, and not more than half a tie spacing below the lowest horizontal reinforcement in members supported above.
* (d) Where beams or brackets frame into all sides of a column, ties shall be terminated not more than 75 mm below lowest reinforcement in such beams or brackets.
#### 9.11.2.3
For walls with average compressive stress in concrete due to effective prestress force only equal to or greater than 1.6 N/mm2 , minimum reinforcement required by Sec 6.6.3 shall not apply where structural analysis shows adequate strength and stability.
### 9.11.3 Volumetric Spiral Reinforcement Ratio
Volumetric spiral reinforcement ratio, $\rho_s$ shall be not less than the value given by
$$
\rho_s = 0.45\left(\frac{A_g}{A_{ch}} - 1\right)\frac{f_c'}{f_{yt}} \tag{6.9.11}
$$
Where, the value of $f_{yt}$ in Eq. 6.9.11 shall not exceed 700 N/mm2 . For $f_{yt}$ greater than 420 N/mm2 , lap splices according to Sec 9.9.3.1(a) shall not be used.
* (a) Spiral reinforcement shall be spliced, if needed, by any one of the following methods:
Lap splices not less than the larger of 300 mm and the length indicated in Sec 8.1.9.3 (a) to (e) of Chapter 8 and summarized below:
* (i) deformed uncoated bar or wire $48d_b$
* (ii) plain uncoated bar or wire $72d_b$
* (iii) epoxy-coated deformed bar or wire $72d_b$
* (iv) plain uncoated bar or wire with a standard stirrup or tie hook in accordance with Sec 8.1.9.3 (d) of Chapter 8 at ends of lapped spiral reinforcement.
* (b) The term “standard hook” as used in this Code shall mean one of the following:
* (i) 180-degree bend plus $4d_b$ extension, but not less than 65 mm at free end of bar.
* (ii) 90-degree bend plus $12d_b$ extension at free end of bar.
* (c) For stirrup and tie hooks
* (i) No. 16 bar and smaller, 90o bend plus $6d_b$ extension at free end of bar; or
* (ii) No. 19, No. 22 bar and No. 25 bar, 90o bend plus $12d_b$ extension at free end of bar; or
* (iii)No. 25 bar and smaller, 135o bend plus $6d_b$ extension at free end of bar.
## 9.12 Slab Systems
### 9.12.1
Factored moments and shears in prestressed slab systems reinforced for flexure in more than one direction shall be determined in accordance with provisions of Sec 6.5.7 Chapter 6 or by more detailed design procedures.
### 9.12.2
$\phi M_n$ of prestressed slabs with loads and load combinations required by Chapter 2 and 6 at every section shall be greater than or equal to *Mu* considering Sections 9.10.3 and 9.10.4. $\phi V_n$ (design strength) of prestressed slabs at columns following Chapter 6 shall be greater than or equal to *Vu* (the required strength, Chapter 2).
### 9.12.3
At service load conditions, all serviceability limitations, including limits on deflections, shall be met, with appropriate consideration of the factors listed in Sec 9.10.2.
### 9.12.4
For uniformly distributed loads, spacing of tendons or groups of tendons in at least one direction shall not exceed the smaller of eight times the slab thickness and 1.5 m. Spacing of tendons also shall provide a minimum average effective prestress of 0.9 N/mm2 on the slab section tributary to the tendon or tendon group. For slabs with varying cross section along the slab span, either parallel or perpendicular to the tendon or tendon group, the minimum average effective prestress of 0.9 N/mm2 is required at every cross section tributary to the tendon or tendon group along the span. Concentrated loads and opening in slabs shall be considered when determining tendon spacing.
### 9.12.5
In slabs with unbonded tendons, bonded reinforcement shall be provided in accordance with Sections 9.9.4.3 to 9.9.4.5.
### 9.12.6
Except as permitted in Sec 9.12.7, in slabs with unbonded tendons, a minimum of two 12.7 mm diameter or larger, seven-wire post-tensioned strands shall be provided in each direction at columns, either passing through or anchored within the region bounded by the longitudinal reinforcement of the column. Outside column and shear cap faces, these two structural integrity tendons shall pass under any orthogonal tendons in adjacent spans. Where the two structural integrity tendons are anchored within the region bounded by the longitudinal reinforcement of the column, the anchorage shall be located beyond the column centroid and away from the anchored span.
### 9.12.7
Prestressed slabs not satisfying Sec 9.12.6 shall be permitted provided they contain bottom reinforcement in each direction passing within the region bounded by the longitudinal reinforcement of the column and anchored at exterior supports as required by Sec 6.5.3.8 Chapter 6. The area of bottom reinforcement in each direction shall be not less than 1.5 times that required by Eq. 6.9.12 as given below.
$$
A_{s,min} = \frac{0.25\sqrt{f_c'}}{f_y}b_wd \tag{6.9.12}
$$
and not less than $2.1b_wd/f_y$, where $b_w$ is the width of the column face through which the reinforcement passes. Minimum extension of these bars beyond the column or shear cap face shall be equal to or greater than the bar development length required by Sec 8.2.
### 9.12.8
In lift slabs, bonded bottom reinforcement shall be detailed in accordance with Sec 9.12.9.
### 9.12.9
In slabs with shear heads and in lift slab construction where it is not practical to pass to the bottom bars, required by bar detailing requirement of Sec 6.5.3.8 Chapter 6, at least two bonded bars or wires in each direction shall pass through the shear head or lifting collar as close to the column as practicable and be continuous or spliced with a Class A splice. At the exterior columns, the reinforcement shall be anchored the spear head or lifting collar.
## 9.13 Post-Tensioned Tendon Anchorage Zones
### 9.13.1 Division into Zones
The anchorage zone shall be considered as composed of two zones as described below and shown in Figure 6.9.1.
* (a) The local zone is the rectangular prism (or equivalent rectangular prism for circular or oval anchorages) of concrete immediately surrounding the anchorage device and any confining reinforcement;
* (b) The general zone is the anchorage zone beyond the local zone.
![Diagram showing anchorage zones including local zone and general zone for post-tensioned tendons]()
### 9.13.2 Local Zone
#### 9.13.2.1
Design of local zones shall be based upon the factored prestressing force, $P_{pu}$ and the requirements of Sections 9.9.2 (d)-(f) and 9.13.2.2.
#### 9.13.2.2
For post-tensioned anchorage zone design, a load factor of 1.2 shall be applied to the maximum steel jacking force.
#### 9.13.2.3
Local-zone reinforcement shall be provided where required for proper functioning of the anchorage device.
### 9.13.3 General Zone
#### 9.13.3.1
Design of general zones shall be based upon the factored prestressing force, $P_{pu}$ and the requirements of Sec 9.4.14.3 b and c.
#### 9.13.3.2
General-zone reinforcement shall be provided where required to resist bursting, spalling, and longitudinal edge tension forces induced by anchorage devices. Effects of abrupt change in section shall be considered.
The general zone requirements of Sec 9.13.3.2 are satisfied by Sections 9.13.4, 9.13.5, and 9.13.6 and whichever one of Sec 9.4.15.2 or Sec 9.4.15.3 or Sec 9.4.16.3 is applicable.
### 9.13.4 Design Methods
#### 9.13.4.1
The following methods shall be permitted for the design of the general zones of the prestressed components provided that the specific procedures used result in prediction of strength in substantial agreement with results of comprehensive tests:
* (a) Equilibrium-based plasticity models (strut-and-tie models);
* (b) Linear stress analysis (including finite element analysis or equivalent); or
* (c) Simplified equations where applicable.
#### 9.13.4.2
Simplified equations shall not be used where member cross-sections are nonrectangular, where discontinuities in or near the general zone cause deviations in the force flow path, where minimum edge distance is less than 1- 1/2 times the anchorage device lateral dimension in that direction, or where multiple anchorage devices are used in other than one closely spaced group.
#### 9.13.4.3
The stressing sequence shall be considered in the design and specified on the design drawings.
#### 9.13.4.4
Three-dimensional effects shall be considered in design and analyzed using three-dimensional procedures or approximated by considering the summation of effects for two orthogonal planes.
#### 9.13.4.5
For anchorage devices located away from the end of the member, bonded reinforcement shall be provided to transfer at least $0.35A_{ps}f_{pu}$ into the concrete section behind the anchor. Such reinforcement shall be placed symmetrically around the anchorage devices and shall be fully developed both behind and ahead of the anchorage devices.
#### 9.13.4.6
Where tendons are curved in the general zone, except for monostrand tendons in slabs or where analysis shows reinforcement is not required, bonded reinforcement shall be provided to resist radial and splitting forces.
#### 9.13.4.7
Except for mono-strand tendons in slabs or where analysis shows reinforcement is not required, minimum reinforcement with a nominal tensile strength equal to 2 percent of each factored prestressing force shall be provided in orthogonal directions parallel to the back face of all anchorage zones to limit spalling.
#### 9.13.4.8
Tensile strength of concrete shall be neglected in calculations of reinforcement requirements.
### 9.13.5 Nominal Material Strengths
#### 9.13.5.1
Tensile stress at nominal strength of bonded reinforcement is limited to for nonprestressed reinforcement and to \ for prestressed reinforcement. Tensile stress at nominal strength of unbounded prestressed reinforcement for resisting tensile forces in the anchorage zone shall be limited to \ = ! + 70.
#### 9.13.5.2
Except for concrete confined within spirals or hoops providing confinement equivalent to that corresponding to Eq. 6.9.11, compressive strength in concrete at nominal strength in the general zone shall be limited to 0.7¥gr .
#### 9.13.5.3
Concrete strength at transfer (Anchorage): Unless oversize anchorage devices are sized to compensate for the lower compressive strength or the prestressing steel is stressed to no more than 50 percent of the final prestressing force, prestressing steel shall not be stressed until compressive strength of concrete as indicated by tests consistent with the curing of the member, is at least 28 N/mm2 for multi-strand tendons or at least 17 N/mm2 for single-strand or bar tendons. Compressive strength of concrete at the time of post-tensioning shall be specified in the contract documents and in design drawings.
### 9.13.6 Detailing Requirements
Selection of reinforcement sizes, spacing, cover, and other details for anchorage zones shall make allowances for tolerances on the bending, fabrication, and placement of reinforcement, for the size of aggregate, and for adequate placement and consolidation of the concrete.
## 9.14 Design of Anchorage Zones For Monostrand or Single 16 Mm Diameter Bar Tendons
### 9.14.1 Local Zone Design
Monostrand or single 16 mm diameter or smaller diameter bar anchorage devices and local zone reinforcement shall meet the requirements of ACI 423.7 or the special anchorage device requirements of Sec 9.15.2.
### 9.14.2 General Zone Design for Slab Tendons
#### 9.14.2.1
For anchorage devices of 12.7 mm diameter or smaller diameter strands in normal weight concrete slabs, minimum reinforcement meeting the requirements of Sections 9.14.2.2 and 9.14.2.3 shall be provided unless a detailed analysis satisfying Sec 9.13.4 shows such reinforcement is not required.
#### 9.14.2.2
Two horizontal bars at least 12 mm diameter in size shall be provided parallel to the slab edge. They shall be permitted to be in contact with the front face of the anchorage device and shall be within a distance of h/2 ahead of each device. Those bars shall extend at least 150 mm either side of the outer edges of each device.
#### 9.14.2.3
If the center-to-center spacing of anchorage devices is 300 mm or less, the anchorage devices shall be considered as a group. For each group of six or more anchorage devices, (n+1) hairpin bars or closed stirrups at least No. 10 in size shall be provided, where n is the number of anchorage devices. One hairpin bar or stirrup shall be placed between each anchorage device and one on each side of the group. The hairpin bars or stirrups shall be placed with the legs extending into the slab perpendicular to the edge. The center portion of the hairpin bars or stirrups shall be placed perpendicular to the plane of the slab from 3h/8 to h/2 ahead of the anchorage devices.
#### 9.14.2.4
For anchorage devices not conforming to Sec 9.14.2.1, minimum reinforcement shall be based upon a detailed analysis satisfying Sec 9.13.4.
### 9.14.3 General Zone Design for Groups of Monostrand Tendons in Beams and Girders
Design of general zones for groups of monostrand tendons in beams and girders shall meet the requirements of Sections 9.13.3 and 9.13.4.
## 9.15 Design of Anchorage Zones For Multi-Strand Tendons
### 9.15.1 Local Zone Design
Basic multistrand anchorage devices and the related local and general zone reinforcement shall meet the requirements of AASHTO “LRFD Bridge Design Specifications (SI), 2007”, Articles 5.10.9.6, Approximate Stress Analysis and Design, and 5.10.9.7, Design of Local Zones.
Special Anchorage Devices (AASHTO “LRFD Bridge Design Specifications (SI), 2007”, Articles 5.10.9.7.3) requires that special anchorage devices that do not satisfy the requirements specified in Sec 9.15.1, they have been tested by an independent testing agency acceptable to the Engineer and have met the acceptance criteria specified in Articles 10.3.2 and 10.3.2.3.10 of AASHTO LRFD Bridge Construction Specifications.
### 9.15.2 Special Anchorage Devices
Where special anchorage devices are to be used, supplemental skin reinforcement shall be furnished in the corresponding regions of the anchorage zone, in addition to the confining reinforcement specified for the anchorage device. This supplemental reinforcement shall be similar in configuration and at least equivalent in volumetric ratio to any supplementary skin reinforcement used in the qualifying acceptance tests of the anchorage device.
### 9.15.3 General Zone Design
Design for general zones for multistrand tendons shall meet the requirements of Sections 9.13.3 to 9.13.5.
## 9.16 Cold Drawn Low Carbon Wire Prestressed Concrete (Cwpc)
### 9.16.1
CWPC (Cold drawn wire prestressed concrete) is termed as prestressed concrete technology of Chinese pattern. This technology is a modification of conventional prestressed concrete. In the conventional prestressed concrete high strength wire is used as reinforcement while in Chinese pattern cold drawn low carbon mild steel wire is used as such this technology is named as cold drawn wire prestressed concrete. In short it is termed as CWPC. CWPC technology is a process whereby cold drawn low carbon steel wire has been adopted as reinforcement for pre-fabricated prestressed concrete members of medium and small size as produced by pre tensioning method. On the other hand, large size structural members are produced by conventional prestressed concrete. The main features and advantages of CWPC technology can be summarized as follows:
* (a) Availability (Availability of materials): The raw material of cold drawn wire is made from low carbon mild steel which can be supplied by the local mills. The tensioning process of cold-drawn wire and production of pre-cast members are also simple and very easy to handle.
* (b) Simplicity (Simplicity of equipment and devices for production): The cold process of low carbon mild steel and prefabrication process of members are done using simple equipment and devices. The precise and large sized equipment are not necessary. The production techniques of manufacturing members are rather simple.
* (c) Quality (Good in quality): The members so manufactured have high crack resistance and stiffness. After pre-tensioning no crack would occur under the service load, thus the wires within the concrete members are well protected. In contrast to conventional reinforced concrete members under the same service conditions, they have comparatively high durability to ensure long term quality.
* (d) Economy (Low cost): The cold drawn low carbon steel wire used for prestressing is made of ordinary hot-rolled carbon steel coil rod. This is processed at room temperature through a special wire drawing die. The low carbon coil rods are manufactured by the steel mills; the wires are processed at the construction site or in a prefabrication plant; or are supplied by the cold drown wire plants as readymade products. By cold drawing the low carbon rod into wires the usable strength is enhanced about twice as much as that of the coil rod. This reduces the amount of steel required in prefabricating prestressed concrete members.
* (e) Therefore, in comparison with conventional reinforced concrete reinforced with common carbon steel, a prestressed concrete member reinforced with cold drawn wire would have saving of steel consumption between 30-40%. Furthermore, since prestressed concrete members have high stiffness a reduction of cross section of members is possible. A considerable amount of concrete can also be saved and hence transportation, handling and erection work can be reduced.
* (f) Light weight (Lightness in weight): As already mentioned that the stiffness of prestressed concrete members may be enhanced, the dimension of its cross-section can be reduced correspondingly. This not only results in reduction of concrete volume but also its dead weight which is estimated as 10-30%.
### 9.16.2 Materials
Basically the materials used in CWPC technology are steel and concrete.
* (a) Steel: steel used for CWPC is obtained by cold drawing. Cold drawing as already mentioned is a process of reducing the diameter of the coil rod by forcing it to pass through a conical die. By this process, the usable strength of steel can be increased by nearly 100%.
* (b) Concrete: The requirement of concrete in CWPC is same as that of ordinary reinforced concrete.
### 9.16.3 Design
Similar to other reinforced concrete structures, CWPC structures have a complete set of design specification and computational approaches by which various members of the CWPC can be designed. In the design of prestressed members the function of pre-stressing force and pre-stressing losses should be calculated. CWPC members should be checked for its strength, stability and cracking resistance respectively at different stages including service, manufacturing, handling, erection and construction. In designing members conformity to local specifications should be considered.
Cold drawn low carbon wire conforming to ASTM A615 or equivalent may be permitted for prestressing provided the mechanical requirements shown in Table 6.9.5 are satisfied.
Table 6.9.5: Tensile Strength and Elongation of Cold Drawn Wire
| Diameter of wire | Minimum tensile | Minimum elongation |
| ---------------- | --------------------------- | ------------------ |
| (mm) | strength (N/mm2) | (percent) |
| 3 | 650 | 2.0 |
| 4 | 600 | 2.5 |
| 5 | 550 | 3.0 |
## 9.17 External Post-Tensioning
### 9.17.1
Post-tensioning tendons shall be permitted to be external to any concrete section of a member. The strength and serviceability design methods of this Code shall be used in evaluating the effects of external tendon forces on the concrete structure.
### 9.17.2
External tendons shall be considered as unbonded tendons when computing flexural strength unless provisions are made to effectively bond the external tendons to the concrete section along its entire length.
### 9.17.3
External tendons shall be attached to the concrete member in a manner that maintains the desired eccentricity between the tendons and the concrete centroid throughout the full range of anticipated member deflection.
### 9.17.4
External tendons and tendon anchorage regions shall be protected against corrosion, and the details of the protection method shall be indicated on the drawings or in the project specifications.
## 9.18 Performance Requirement Of Prestressed Concrete Design
### 9.18.1 Classification of Performance Requirement
After the outline of the member dimensions are determined and the most suitable kind and type of prestressing options are selected at the structural planning stage, the prestressed concrete non-composite and composite structures and members shall satisfy all of the required performances such as safety, serviceability, restorability, durability, reparability, societal and environmental compatibility, etc. at every stage of design, construction and maintenance throughout the design life of the structure. Table 6.9.6 gives the performance requirement of prestressed concrete structures and components and related performance items.
Table 6.9.6: Classification of Performance Requirement for Prestressed Concrete Structures
| Performance
requirements | Performance
item | Examples of check items | Example of verification
index |
| ------------------------------------------------ | ----------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
| Safety | Structural
safety | Resistance of whole
structure, components,
stability, deformation
performance | Stress resultant, stress |
| | Public safety | Injury to users and third
parties | - |
| Serviceability | Live load
operating
performance | Soundness and rigidity of
structures /members under
usual conditions | Floor flatness, deformation
of main girder |
| | User comfort | User-comfort under walking-
induced vibrations | Natural frequency of main
girders |
| Restorability | Restorability
after
earthquake,
cyclone, tidal
bore, fire, etc. | Level of damage (ease of
restoration) | Response value (damage
level)/ limit value of
performance (damage
level) |
| Durability | Fatigue
resistance | Fatigue durability against
variable actions | Equivalent stress range/
allowable stress range |
| | Corrosion
resistance | Rust prevention and
corrosion protection
performance of steel material | Corrosion environment
and surface finish, paint
specification |
| | Resistance to
material
deterioration | Concrete deterioration | Water- cement ratio, cover
of concrete |
| | Maintainability | Ease of maintenance
(inspection, ease of repair,
etc.)and ease of restoration | - |
| Social and
environmental
compatibility | Social
compatibility | Appropriateness of partial
factor (consideration of
social importance of
structure) | Partial factor, structural
factor, etc. |
| | Economic
rationality | Social utility during life cycle
of structure | Life cycle cost (LCC), life
cycle utility (LTU) |
| | Environment
al
compatibility | Noise, vibration,
environmental impact,
aesthetics, etc. | Noise and vibration levels
for surrounding residents,
aesthetic reaction to
structural shape and color,
monumental aspect, etc. |
| Constructabili
ty / | Safety during
construction | Safety during construction | Stress resultant, stress,
deformation |
| workability | Initial
soundness | Material quality, welding
quality, etc. | Material properties,
workmanship |
| | Ease of
construction | Ease of fabrication and
construction work | User-friendly construction
methodology conceived at
design stage |
### 9.18.2 Performance Verification Method
* (a) Performance verification shall be based on the partial factor method on the basis of reliability theory and as a standard design procedure, it shall be based on the limit state method.
* (b) In general verification shall be based on design responses to design actions, design limits as determined by design material strengths, and individual partial factors. The performance of the structure shall, in general, be verified using Equations 6.9.13 and 6.9.14:
$$
\frac{\gamma_g S_k}{\gamma_1 f_k} \leq 1.0 \tag{6.9.13}
$$
$$
\frac{\gamma_g(S_k + Q_k)}{\gamma_1(f_k/\gamma_f)} \leq 1.0 \tag{6.9.14}
$$
Where, $R_d$ : design resistance; $f_k$ : characteristic value of material strength; $\gamma_f$ : material factor; $\gamma_1$ : structural member factor
* (c) During design, a verification shall be carried out for every limit state that can be considered.
* (d) The flow chart explaining the concept of verification of safety is given in Figure 6.9.2.
![Flow chart explaining the concept of verification of safety relating material strength, design resistance, actions, action effects, and limit state verification]()
### 9.18.3 Partial Factors
* (a) Partial factors shall be determined on the concept given (i) and (ii) below.
* (i) The material factor, structural member factor, structural analysis factor, and action factor shall be determined in consideration of
* unfavorable deviations from characteristic values,
* uncertainties in computational accuracy, and
* discrepancies between design and practice with respect to actions or structures and materials.
* Table 6.9.7 shows the standard values of partial factors.
* (ii) The structural factor ¡g shall be determined according to structural importance and also the social and economic impact of the structure reaching its limit state.
Table 6.9.8 shows the standard values of structural factor ¡õ for different performance items.
Table 6.9.7: Standard Values of Partial Factors
| Performance Item | Action
Factor,f | Structural Analysis
Factor,fg | Material
Factor,f1 | Structural Member
Factor,f |
| -------------------------------------------------- | -------------------- | ---------------------------------- | ----------------------- | ------------------------------- |
| Structural safety | 1.0῀1.6 | 1.0῀1.1 | 1.0῀1.05 | 1.0῀1.3 |
| Serviceability | 1.0 | 1.0 | 1.0῀1.05 | 1.0 |
| (user comfort) | | | | |
| Durability | 1.0῀1.1 | 1.0 | 1.0 | 1.0῀1.1 |
| (fatigue
resistance) | | | | |
| Table 6.9.8: Standard Values of Structural Factors | | | | |
| Performance item | Structural factorfõ |
| ------------------------------------------------------------- | ------------------- |
| Structural safety | 1.0῀1.2 |
| Serviceability (User comfort) | 1.0 |
| Durability (fatigue resistance) | 1.0 |
| Division B: Material and Construction (Sections 9.19 To 9.21) | |
## 9.19 Materials
### 9.19.1 Concrete Ingredients and Applicable ASTM Standards
Table 6.9.9 shows the list of commonly applicable standards for cement, coarse and fine aggregates, admixtures and mixing water.
Table 6.9.9: Applicable Standards for Cement, Coarse and Fine Aggregates, Admixtures and Water
| Material | Designation of
the Standard | Title of the Standard |
| ------------------------------------ | -------------------------------- | ------------------------------------------------------------------------------------------------------- |
| Concrete | ASTM C39 | Compression testing of cylindrical concrete
specimens |
| Cement | BDS EN 197-1 | Part
1:
Composition,
specifications
and
conformity criteria for common cements |
| Fine and
Coarse
aggregates | ASTM C136 | Standard test method for sieve analysis of fine
and coarse aggregates |
| | ASTM C40 | Standard test method for organic impurities in
fine aggregates for concrete |
| | ASTM C142 | Clay lumps and friable particles |
| | ASTM C127 | Specific gravity and absorption of coarse
aggregate |
| | ASTM C128 | Specific gravity and absorption of fine aggregate |
| | ASTM C131 | Degradation of small-size coarse aggregate by
L.A. abrasion test |
| | ASTM C29 | Unit weights and voids in aggregates |
| | ASTM C70 | Surface moisture in fine aggregate Soundness of |
| | | aggregates by use of sodium sulfate or
magnesium sulfate |
| | ASTM C88 | Soundness of aggregates by use of sodium
sulfate or magnesium sulfate |
| | ASTM C227 | Alkali reactivity, potential of cement aggregate
combinations |
| | ASTM C1260 | Potential alkali reactivity of aggregates (Mortar-
bar method) |
| | ASTM D2419 | Sand equivalent value of soils and fine aggregate |
| Admixtures | ASTM C494 | Type A – Water reducing |
| | | Type B – Retarding |
| | | Type C – Accelerating |
| | | Type D – Water reducing and retarding
Type E – Water reducing and accelerating |
| | | Type F – Water reducing, high range
Type G – Water reducing, high range and
retarding |
| | | Type S – Specific performance admixture |
| Mixing Water | ASTM C
1602/C1602M | Standard specification for mixing water used in
the production of hydraulic cement concrete |
### 9.19.2 Reinforcing Steel and Applicable Standards
Table 6.9.10 shows the types of reinforcing steel with the ASTM and BDS Designation standard specifications.
Table 6.9.10: List of Standards for the Reinforcing Steel
| Material | Designation of
the Standard | Title of the Standard |
| ----------------- | -------------------------------- | ------------------------------------------------------------------------------------------------------------------------ |
| Reinforcing Steel | BDS ISO 6935-2 | Bangladesh standard, Steel for the reinforcement of concrete, Part 2: Ribbed bars (1st revision) |
| | ASTM A615/A615M | Standard specifications for deformed and plain carbon steel bars for concrete reinforcement |
| | ASTM A706/A706M | Standard specifications for low-alloy steel deformed and plain carbon steel bars for concrete reinforcement |
| | A775/A775M | Standard Specification for Epoxy-Coated Steel Reinforcing Bars |
| | A884/A884M | Standard Specification for Epoxy-Coated Steel Wire and Welded Wire Reinforcement |
| | A934/A934M | Standard Specification for Epoxy-Coated Prefabricated Steel Reinforcing Bars |
| | ASTM A996/A996M | Specification for Axle Steel Deformed and Plain Bars for Concrete Reinforcement |
| | ASTM A996/A996M | Specification for Rail Steel Deformed and Plain Bars for Concrete Reinforcement" Including Supplementary Requirements S1 |
### 9.19.3 Prestressing Steel and Applicable ASTM Standards
Table 6.9.11 shows the types of high tensile prestressing steel and cold drawn wires used for prestressing, with the ASTM Designation standard specifications.
Table 6.9.11: List of Standards for the Prestressing Steel
| Material | Designation of the
Standard | Title of the Standard |
| ------------------ | -------------------------------- | --------------------------------------------------------------------------------------- |
| Prestressing Steel | A416/A416M | Standard Specification for Steel Strand, Uncoated Seven-Wire for Prestressed Concrete |
| | A421/A421M | Standard Specification for Uncoated Stress-Relieved Steel Wire for Prestressed Concrete |
| | ASTM A648 | Standard specification for steel, wire, hard drawn for prestressing concrete pipe |
| | A722/A722M | Standard Specification for Uncoated High-Strength Steel Bars for Prestressing Concrete |
## 9.20 Construction of Prestressed Concrete Structures
### 9.20.1 Corrosion Protection for Unbonded Tendons
#### 9.20.1.1
Unbonded prestressing steel shall be encased with sheathing. The prestressing steel shall be completely coated and the sheathing around the prestressing steel filled with suitable material to inhibit corrosion.
#### 9.20.1.2
Sheathing shall be watertight and continuous over entire length to be unbonded.
#### 9.20.1.3
For applications in corrosive environments, the sheathing shall be connected to all stressing, intermediate and fixed anchorages in a water tight fashion.
#### 9.20.1.4
Unbonded single-strand tendons shall be protected against corrosion in accordance with ACI 423.7.
### 9.20.2 Post-tensioning Ducts
#### 9.20.2.1
Ducts for grouted tendons shall be mortar- tight and nonreactive with concrete, prestressing steel, grout, and corrosion inhibitor.
#### 9.20.2.2
Ducts for grouted single-wire, single-strand, or single-bar tendons shall have an inside diameter at least 6 mm larger than the prestressing steel diameter.
#### 9.20.2.3
Ducts for grouted multiple wire, multiple strand, or multiple bar tendons shall have an inside cross-sectional area at least two times the crosssectional area of the prestressing steel.
#### 9.20.2.4
Ducts shall be maintained free of ponded water if members to be grouted are exposed to temperatures below freezing prior to grouting.
### 9.20.3 Grout for Bonded Tendons
#### 9.20.3.1
Grout shall consist of Portland cement and water; or Portland cement, sand, and water.
#### 9.20.3.2
Materials for grout shall conform to Sections 9.20.3.3 to 9.20.3.5.
#### 9.20.3.3
Portland cement shall conform to Sec 9.19.1.
#### 9.20.3.4
Water shall conform to Sec 9.19.1.
#### 9.20.3.5
Sand, if used, shall conform to Sec 9.19.1 except that gradation shall be permitted to be modified as necessary to obtain satisfactory workability.
#### 9.20.3.6
Admixtures conforming to Sec 9.19.1 and known to have no injurious effects on grout, steel, or concrete shall be permitted. Calcium chloride shall not be used.
### 9.20.4 Selection of Grout Proportions
#### 9.20.4.1
Proportions of materials for grout shall be based on either (a) or (b) below.
* (a) Results of tests on fresh and hardened grout prior to beginning grouting operations; or
* (b) Prior documented experience with similar materials and equipment and under comparable field conditions.
#### 9.20.4.2
Cement used in the Work shall correspond to that on which selection of grout proportions was based.
#### 9.20.4.3
Water content shall be minimum necessary for proper pumping of grout; however, water-cement ratio shall not exceed 0.45 by weight.
#### 9.20.4.4
Water shall not be added to increase grout flowability that has been decreased by delayed use of the grout.
### 9.20.5 Mixing and Pumping of Grout
#### 9.20.5.1
Grout shall be mixed in equipment capable of continuous mechanical mixing and agitation that will produce uniform distribution of materials, passed through screens, and pumped in a manner that will completely fill the ducts.
#### 9.20.5.2
Temperature of members at time of grouting shall be above 2°C and shall be maintained above 2°C until field-cured 50 mm cubes of grout reach a minimum compressive strength of 5.5 N/mm2 .
#### 9.20.5.3
Grout temperatures shall not be above 32°C during mixing and pumping.
### 9.20.6 Protection for Prestressing Steel During Welding
Burning or welding operations in the vicinity of prestressing steel shall be performed so that prestressing steel is not subject to excessive temperatures, welding sparks, or ground currents.
### 9.20.7 Application and Measurement of Prestressing Force
#### 9.20.7.1
Prestressing force shall be determined by both of (a) and (b):
* (a) Measurement of steel elongation. Required elongation shall be determined from average load-elongation curves for the prestressing steel used;
* (b) Observation of jacking force on a calibrated gage or load cell or by use of a calibrated dynamometer.
Cause of any difference in force determination between (a) and (b) that exceeds 5 percent for pretensioned elements or 7 percent for post-tensioned construction shall be ascertained and corrected.
#### 9.20.7.2
Where the transfer of force from the bulk- heads of pretensioning bed to the concrete is accomplished by flame cutting prestressing steel, cutting points and cutting sequence shall be predetermined to avoid undesired temporary stresses.
#### 9.20.7.3
Long lengths of exposed pretensioned strand shall be cut near the member to minimize shock to concrete.
#### 9.20.7.4
Total loss of prestress due to unreplaced broken prestressing steel shall not exceed 2 percent of total prestress.
### 9.20.8 Post-tensioning Anchorages and Couplers
#### 9.20.8.1
Anchorages and couplers for bonded and unbonded tendons shall develop at least 95 percent of the $f_{pu}$ when tested in an unbonded condition, without exceeding anticipated set. For bonded tendons, anchorages and couplers shall be located so that 100 percent of $f_{pu}$ shall be developed at critical sections after the prestressing steel is bonded in the member.
#### 9.20.8.2
Couplers shall be placed in areas approved by the licensed design professional and enclosed in housing long enough to permit necessary movements.
#### 9.20.8.3
In unbonded construction subject to repetitive loads, attention shall be given to the possibility of fatigue in anchorages and couplers.
#### 9.20.8.4
Anchorages, couplers, and end fittings shall be permanently protected against corrosion.
## 9.21 Performance Requirement of Material
### 9.21.1
The fundamental performance requirement of materials forming the structure is that they should be able to resist actions such as the various loadings to which the structure is exposed.
### 9.21.2
Materials forming the structure should not reach unexpected limit states as a result of deterioration phenomena during the working life of the structure.
### 9.21.3
Materials-related energy consumption and CO2 discharges should be minimized, while recyclability should be high.
Any materials that escape into the surrounding environment during construction and service should not have a strong impact on human beings, animals and plants.
Commentary:
Corresponding to design requirements, the materials should be evaluated to ensure that their properties are suitable with respect to strength (tensile, compressive and shear), deformation (e.g. elastic modulus), heat resistance and water tightness.
The characteristic values obtained from the tests, complying appropriate BDS, ASTM, BS, or equivalent standards, on such specimens should be converted to suit the design calculation models using appropriate conversion factors or functions. The characteristic value of material strength $f_k$ is calculated from test results using Eq. 6.9.15.
$$
f_k = f_m - k\sigma \tag{6.9.15}
$$
Where, $f_m$: mean of test values, $\sigma$: standard deviation of test values, and $k$: coefficient of variance. The coefficient k is determined from the probability of obtaining a test value less than the characteristic value and the probability distribution of test results. The 5% fractile value is often taken as the characteristic value. In this case, the value of k is 1.64 if the normal distribution is assumed for the test values.
At the structural design stage, verification shall be performed so that response value is less than or equal to the limit value of performance throughout both construction period and working life. At the end of construction stage, just completed structure shall fulfill the all required performances considered in its design.
**Division C : Maintenance (Sections 9.22 To 9.27)**
## 9.22 General
If the prestressed concrete structure is designed and constructed in accordance with the appropriate concepts described in Part I and II of this Chapter, based on which the durability is checked by verifying the performance requirements of the concrete and its constituent materials, it is not likely that structural deterioration would become so significant as to degrade the performance of the structure. On the other hand it is not easy to estimate the performance degradation process of the structure during its service life accurately. Also, it is difficult to completely avoid construction defects at all construction stages. Therefore, the new structure should be appropriately maintained by routine and regular inspections, based on an adequate maintenance plan formulated at the design stage.
For existing structures, deterioration may be evident in some cases, with the performance having been degraded. The defects of such structures should be accurately assessed and identified as initial defects, damage, or deteriorations. Major causes for such defects should be identified subsequently so that appropriate remedial actions can be selected. The initial defects and damage should be treated promptly and appropriately including emergency treatments. When the deterioration that would degrade the performance is evident, the deterioration mechanisms should be identified and appropriate maintenance, carried out based on the results of deterioration prediction and performance degradation evaluation.
## 9.23 Classification of Maintenance Action
Maintenance actions shall be classified into different categories depending on such factors as the importance of the structure, design life, impact on a third party, environmental conditions, ease of maintenance, and cost.
In the view of the above, four categories are recommended for the classifications of the maintenance actions:
### 9.23.1 Category A : Preventive Maintenance
Maintenance to prevent deterioration which would otherwise lead to unsatisfactory structural performance. Category A structures are those
* for which remedial actions are difficult to take after deterioration becomes apparent;
* of which deterioration must not be apparent;
* having a long design life.
Structures in this category generally have a high degree of importance which in many cases require monitoring.
### 9.23.2 Category B : Corrective Maintenance
Maintenance to restore the performance level and/or to reduce the rate of deterioration so as to maintain satisfactory structural performance. Category B structures are those for which
* remedial measures can be taken after deterioration becomes apparent;
* apparent deterioration causes no appreciable inconvenience.
### 9.23.3 Category C : Observational Maintenance
Maintenance in which visual inspection is necessary without any remedial action regardless of the deterioration level. Category C structures are those
* for use as long as they are usable;
* for which ensuring safety from threats posed to third parties is the only requirement.
### 9.23.4 Category D : Indirect Maintenance
Maintenance in which no direct inspection is necessary or possible. Category D structures are those for which direct inspection is extremely difficult. For these reasons, non-inspection maintenance after the initial inspection is carried out not as routine or regular inspection, but as extraordinary inspection following natural disasters, accidents, etc.
## 9.24 Maintenance Record
Records, drawings and related documents prepared during the time of planning, design and construction shall be referred to and made use of while developing an appropriate methodology for maintenance covering inspection and repairs.
Commentary:
A thorough study of the planning, design and construction related documents often provide insights into the inherent weaknesses of the structure which in turn often serve as pointers for further detailed inspection and/or repairs.
Furthermore, a clear record should be kept of the difficulties encountered, remedial actions taken and any deviation from the design drawings. These record also serve as a valuable reference in the design and construction of similar structures and their subsequent inspections.
## 9.25 Inspection
### 9.25.1 General
On the basis of the methods used in the frequency and timing, inspection shall be classified as initial inspection, routine inspection, regular inspection, detailed inspection, extraordinary inspection, and monitoring.
### 9.25.2 Initial Inspection
Initial inspection is intended to examine whether the structure is adequately constructed. It also allows the collection of basic data for initiating a maintenance program. Initial inspection shall also be carried out just after the completion of remedial actions.
Initial inspection should cover the external appearance of the structure, variation of concrete quality, existence of construction defects, construction errors on reinforcing and pretsressing bar arrangement, and so on.
### 9.25.3 Routine Inspections
It shall be carried out on a routine basis at certain intervals without making any specific effort to identify signs of deterioration, if any, and the time of their first appearance. The exact tools to be used and the frequency of such inspections may be decided on the basis of such factors as the likely mechanisms of such deterioration, environmental conditions, importance of the structure, and the maintenance action classification.
A routine inspection should cover the external appearance of the structure including cracks, spalling, delamination, color changes, rust stain from reinforcement, and isolation of free lime from concrete.
### 9.25.4 Regular Inspection
It shall be carried out at regular intervals using appropriate tools to identify signs of deterioration and the time of their first appearance. Efforts shall be made during a regular inspection to observe the structure closely to obtain details which will be difficult to gather during a routine inspection.
Visual inspection and/or hammering inspection are carried out mainly to obtain more details on the items inspected in a routine inspection. In addition, inspections by using appropriate non-destructive tests or taking concrete cores etc. can be effectively combined with the visual inspection.
### 9.25.5 Detailed Inspection
Detailed inspection shall be done when
* (a) some signs of deterioration or a change in the performance level are observed during a routine and/or regular inspection;
* (b) it is difficult to obtain reliable and accurate information during a routine and/or regular inspection;
* (c) it is found that the structural integrity of the structure has been adversely affected by the extent of the deterioration;
* (d) more detailed information is required before deciding on the necessity and scope for undertaking a major repair, rehabilitation or strengthening work.
### 9.25.6 Extraordinary Inspection
It shall be carried out after a structure has been subjected to an accidental load to assess the extent of the damage and the need for remedial actions. Such accidental loads may include those caused by an earthquake, storm, flood, fire, explosion, etc.
## 9.26 Monitoring
The deterioration and/or performance of the concerned structure as determined in 9.6.2, shall be monitored, through continuous recording of the appropriate data, together with routine and regular inspections, so that the appropriate remedial actions can be taken before the deterioration becomes detrimental to the appearance and other performance of the structure.
### 9.26.1 Deterioration Mechanism and Prediction
#### 9.26.1.1 General
The prevailing state of the concerned structure shall be evaluated as properly as possible according to the inspection results, design and construction records, environmental conditions, and any other relevant information. Then when any deterioration is found, the possible causes of the deterioration and the corresponding mechanism can be appropriately estimated.
#### 9.26.1.2 Identification of deterioration mechanisms
Deterioration of a structure is caused by the environmental actions and loading conditions. Environment-oriented deterioration includes carbonation-induced deterioration, chloride-induced deterioration, chemical attack, alkali-aggregate reaction, etc. On the other hand external force-oriented deterioration includes fatigue, excessive loading, and differential settlement of the support.
#### 9.26.1.3 Deterioration factors
Deterioration factors may be classified into those
* (a) external to structures such as temperature, humidity and any other environmental characteristics; and
* (b) internal to the structure such as design parameters and quality control during construction.
Commentary:
Design factors include the geometry of the members/ segments, crack width specifications, concrete cover to reinforcing bar and prestressing steel/ducts, and design strength. Construction factors include material selection, mix proportions, transportation, placement, and curing methods.
#### 9.26.1.4 Determination of deterioration levels and rates
The level of deterioration and/or performance shall be determined based on the results of inspections and simulations using appropriate models for the mechanisms of deterioration.
The following features appearing on the surface of the structure may be used for evaluating the degree of deterioration and the level of performance:
* (a) crack pattern, length and width;
* (b) the extent of delamination, peeling and spalling of concrete cover, and scaling and degradation areas;
* (c) abnormal hammer tapping sound and the extent of abnormality;
* (d) presence and degree of exudation of rust and efflorescence and water leakage.
### 9.26.2 Evaluation and Decision Making
#### 9.26.2.1 General
In general, the deterioration and performance degradation of a structure progress monotonically. The decision, therefore, should be made based on the evaluation outcome of the performance of the structure at the time of inspection and at the end of its design life.
#### 9.26.2.2 Threshold level
The threshold level of the structure’s degraded performance shall be specified in accordance with the requirements of safety, functionality, appearance, societal friendliness and such other factors, taking into consideration the type, importance and maintenance level of the structure and the environmental conditions.
#### 9.26.2.3 Evaluation of inspection results
The results from routine and regular inspections shall be evaluated and a decision shall be made whether a detailed inspection is required or otherwise.
The results from the detailed and/or extraordinary inspections shall be evaluated and a decision shall be made whether a remedial action is required or otherwise.
Immediate remedial actions shall be taken in cases where deterioration, damage and/or initial defects are found to be hazardous to third parties.
## 9.27 Remedial Action
### 9.27.1 General
A remedial action on a deteriorated structure shall be taken on the basis of the inspection results, importance of the structure, maintenance classification, and the threshold level of deterioration and/or performance.
Commentary:
Repair and strengthening are the main techniques of remedial actions of which details are described in Sections 9.2.7.3 and 9.2.7.4 respectively. The following measures are also included in the remedial actions.
Intensified inspection: inspection may be carried out by suitably increasing one or more of the following: frequency of inspection, number of inspection items, and the locations for inspection.
Usage restriction: suitable restriction shall be imposed on the maximum live load that the structure may carry, depending on the level of deterioration observed.
Functional improvement or restoration: this may include an appearance improvement that beautifies a structure with suitably painting or placing additional concrete, and so on.
Dismantling and removal: in a case when the deterioration of a structure is too severe for its structural performance to be sufficiently restored, and dismantling or the removal is one of the choices as the remedial measures.
Special care for emergency: when a deteriorated structure poses an immediate threat to the environment, its users, or third parties, suitable emergency action shall be taken immediately.
### 9.27.2 Selection of Remedial Action
Selection of methods and materials suitable for the relevant deterioration mechanism and degree of performance degradation is particularly important for measures for which wide varieties of methods and materials are available. Care should be taken as the method of restoring the performance may vary depending on the deterioration mechanism, even if the level of performance is the same.
### 9.27.3 Repair
#### 9.27.3.1 General
Repair of a structure refers to the remedial action taken to prevent or slow down its further deterioration and reduce the possibility of damage to its users or third parties.
Types of repair include (i) repair of defects such as cracking and peeling; (ii) removal of concrete damaged by deterioration due to carbonation and such like; (iii) surface coating to prevent re-intrusion of hazardous substances.
#### 9.27.3.2 Preparation and execution
A complete plan for the repair work including methods of repair, materials to be used, and tests to ensure the quality of work, shall be developed before the repair work commences.
Repair works shall be carried out with minimum disturbances to the surrounding environment. Necessary tests to ensure the quality of the repair work shall be carried out. Detailed record of the repair work shall be maintained for future reference.
#### 9.27.3.3 Methods and materials
Some current repair methods and associated materials are
* crack repair by injecting epoxy;
* section repair including patching using polymer cement mortar;
* surface protection by resin or mortar;
* cathodic protection;
* re-alkalization;
* de-salination, wherever required.
**Commentary:**
Development of a repair plan comprises the selection of a repair method suitable for the deterioration mechanism, establishment of the required repair level, and decisions on the repair policy, specifications for the repair materials, sectional dimensions after repair, and execution methods.
### 9.27.4 Strengthening
#### 9.27.4.1 General
Strengthening of a structure refers to the remedial action taken to restore or improve its structural properties including load carrying capacity and stiffness, to a level which is equal to or higher than that of the original design.
**Commentary:**
Strengthening methods include (i) replacement of members; (ii) an increase in the cross-sectional area of concrete; (iii) addition of members; (iv) an increase of the support points; (v) addition of strengthening members; (vi) external prestressing, etc.
#### 9.27.4.2 Preparation and execution
Strengthening of a structure shall be preceded by a thorough investigation of its deterioration considering such factors as the remaining design life, deterioration mechanism, possible causes and extent of deterioration, the remaining and desired load-carrying capacity or stiffness, importance of the structure, maintenance classification, and any remedial actions taken previously.
A complete plan for the strengthening work including design calculations, methods of strengthening, materials to be used, and tests to ensure quality of the work, shall be developed before work commences.
Strengthening work shall be carried out with minimum disturbance to the surrounding environment and the service condition of the structure.
#### 9.27.4.3 Methods and materials
Some current methods and associated materials for strengthening are
* external bonding viz plate or sheet bonding and over or under-laying using steel or carbon sheets;
* external prestressing using additional tension cables;
* addition of girders, braces and/or supports;
* replacement of members;
* seismic isolation.
Commentary:
When selecting a strengthening method, it is necessary to consider effects of strengthening, constructability, cost-effectiveness, and impact on the community/ environment during execution. It is also important to consider the ease of maintenance after strengthening and any influence on the landscape.
### 9.27.5 Record
#### 9.27.5.1 General
Records shall be kept and preserved for future reference. Such records shall include details concerning the design, inspection and evaluation procedures, plans and execution of any repair and/or strengthening work undertaken, and other such information.
#### 9.27.5.2 Preservation
The maintenance records of a structure shall be preserved while the structure remains in service. It is also desirable that such records be preserved for an indefinite period as a useful reference for the construction and maintenance of other similar structures.
Commentary:
It is important to devise a format that makes it easy to understand the history of a structure by simply referring to records. The records should be made accessible at all times.
#### 9.27.5.3 Method and item of recording
Records shall be kept in an easy-to-understand format.
The items to be recorded shall include references to concerned agencies, drawings, immediate and nearby environment, classification of structure, results of deterioration rate estimation, results of any inspections carried out, evaluation of the structure, and details of the plan and actual execution of remedial and other actions.
# Part VI: Structural Design
Source: https://docs.sayed.app/bnbc/part-6-structural-design/index
Loads, soils and foundations, and design of concrete, masonry, and steel structures.
Part VI covers structural design: loads on buildings and structures, soils and foundations, and the design of bamboo, concrete, masonry, and steel structures.
Definitions and general requirements for structural design.
Dead, live, wind, seismic, and other design loads.
Geotechnical investigation and foundation design requirements.
Design requirements for bamboo structures.
Material requirements for concrete.
Strength design provisions for reinforced concrete structures.
Design requirements for masonry structures.
Reinforcement detailing requirements.
Design requirements for prestressed concrete structures.
Design requirements for steel structures.
# Bangladesh National Building Code (BNBC) 2006
Source: https://docs.sayed.app/bnbc2006/index
Predecessor to BNBC 2020; minimum standards for design, construction, use, occupancy, and maintenance of buildings in Bangladesh.
The Bangladesh National Building Code (BNBC) 2006 was prepared by a Steering Committee formed under the Planning Commission in 1991, with consulting services provided by Development Design Consultants Limited, and published by the Housing and Building Research Institute (HBRI) and the Bangladesh Standards and Testing Institution (BSTI). It was repealed and replaced by the [Bangladesh National Building Code (BNBC) 2020](/bnbc/index).
Its purpose is to establish minimum standards for the design, construction, quality of materials, use and occupancy, location, and maintenance of all buildings within Bangladesh, in order to safeguard, within achievable limits, life, limb, health, property, and public welfare.
## Parts
Title, purpose, and scope of the Code; definitions; abbreviations.
Purpose and scope, the code enforcement agency and Building Official, and permits and inspections.
General building requirements and classification of buildings by occupancy and fire-resistance.
Precautionary requirements, means of escape, and fire detection and extinguishing systems.
Scope, definitions, and standards for building materials.
Loads, foundations, and design of masonry, concrete, steel, timber, and ferrocement structures.
Constructional responsibilities, storage and handling, safety during construction, and demolition.
Lighting, electrical installation, HVAC, lifts, water supply, drainage, and fuel gas supply.
Applicability and implementation, and evaluation and compliance.
Scope, general requirements, and specific requirements for various types of sign.
## Citing this Code
Sections are numbered per part and chapter as in the original document (for example, Sec 3.2.3.5 refers to Part 2, Chapter 3, Section 3.2.3.5). Use those numbers, not page numbers, when citing a provision (they're stable across this site's formatting).
# Chapter 1: Title, Scope and General
Source: https://docs.sayed.app/bnbc2006/part-1-scope-and-definitions/chapter-1-title-scope-and-general
## 1.1 Title
The provisions and regulations contained in this document shall constitute and be collectively known and may be cited as the "Bangladesh National Building Code", abbreviated, where desired, as BNBC, and will hereinafter be referred to as the "Code".
## 1.2 Purpose
The purpose of this Code is to establish minimum standards for design, construction, quality of materials, use and occupancy, location and maintenance of all buildings within Bangladesh in order to safeguard, within achievable limits, life, limb, health, property and public welfare. The installation and use of certain equipment, services and appurtenances related, connected or attached to such buildings are also regulated herein to achieve the same purpose.
The provisions of this Code are applicable to all persons of Bangladesh irrespective of class, creed, culture, religion or sex. The Code does not in any way create or otherwise establish or designate any particular class or group of persons who will or should be specially protected or benefited by the provisions of this Code.
The expressed intent of this Code is to insure public safety, health and general welfare insofar as they are affected by the construction, alteration, repair, removal, demolition, use or occupancy of buildings, structures or premises, through structural strength, stability, means of egress, safety from fire and other hazards, sanitation, light and ventilation.
## 1.3 Scope
The provisions of this Code shall apply to the design, construction, use or occupancy, alteration, moving, demolition and repair of any building or structure and to any appurtenances installed therein or connected or attached thereto, except such matters as are otherwise provided for in other ordinances and statutes controlling and regulating buildings.
If for any case different sections of this Code provide different specifications for materials, methods of design or construction, or other requirements, the most restrictive specification shall govern.
In case of any conflict between a general requirement and a specific requirement, the specific requirement shall be applicable.
Unless otherwise explicitly stated in this Code, all references to part, chapter or section numbers or to provisions not specifically identified by number, shall be construed to refer to such part, chapter, section or provision of this Code.
References made to a section without mentioning a part shall be construed to refer to that section of the part in which the reference is made.
The provisions of any appendix in this Code shall not be mandatory unless they are referred to as such in any section of the Code or they are specifically adopted by any regulation.
Inspection conducted or permission granted for any building or plan of building, under the provisions of this Code, shall not be construed as a warranty of the physical condition of such building or the adequacy of such plan. Neither the Authority administering the Code, nor any employee thereof shall be liable in tort for damages for any defect or hazardous or illegal condition or inadequacy in such building or plan, nor for any failure of any component of such building which may occur subsequent to such inspection or granting of permission under the provisions of the Code.
## 1.4 Existing buildings
Buildings which are in existence on the date of promulgation of this Code may have their use or occupancy continued without undergoing any alteration, abandonment or removal unless in the opinion of the Authority such continued use is hazardous to life and property and provided such use or occupancy was legal on the date of promulgation of this Code.
### 1.4.1 Addition and Alteration
Additions, alterations, modifications or repair to an existing building may be made without requiring the existing building to comply with all the requirements of this Code, provided the additions, alterations, modifications or repairs conform to that required for a new building. Such additions or alterations shall not be permitted when the existing building is not in full compliance with the provisions of this Code except when the addition or alteration will result in the existing building or structure being no more hazardous based on life safety, fire safety and sanitation than it was before the addition or alteration was undertaken.
Any building together with the new additions shall not exceed the height, number of storeys and area specified in this Code for new buildings having the relevant occupancy and type of construction. Non-structural alterations or repairs to an existing building or structure which do not adversely affect any structural member, nor reduce the strength of any part of the building or structure to result in an unsafe condition shall be made with materials and components having the required fire resistance.
### 1.4.2 Change of Use
Change in use or occupancy in an existing building may be made when such change complies with the requirements of this Code for a new building and provided such change does not render any part or the whole of the affected building or structure any more hazardous based on life safety, fire safety and sanitation than it was before such change was effected.
## 1.5 Historic and architecturally valuable buildings
A building or structure which has been designated by official action as having special historical or archaeological interest, or a building or structure identified by a legally constituted authority as being architecturally valuable, may be undertaken for repairs, alterations and additions necessary for its preservation, restoration, rehabilitation or continued use provided:
i) the proposed repair, alteration or addition to buildings of historical or archaeological significance is approved by the legally constituted authority, such as the Department of Archaeology;
ii) the proposed repair, alteration or addition to buildings of architectural value does not impair the aesthetic quality and architectural character of such buildings; and
iii) the restored building or structure will be no more hazardous, if any, based on life safety, fire safety and sanitation than the existing building.
See also Sec 3.8 of Part 2 and Sec 1.16 of Part 3.
# Chapter 2: Definitions
Source: https://docs.sayed.app/bnbc2006/part-1-scope-and-definitions/chapter-2-definitions
## 2.1 General
Unless otherwise expressly stated, the abbreviations, terms, phrases, words and their derivations listed below shall, for the purpose of this Code, be construed as set forth in this chapter. Words not explicitly defined shall have their ordinarily accepted meanings as the context implies as provided in *The Concise Oxford Dictionary of Current English*, eighth edition, Allen R.E., Ed., Oxford University Press, New Delhi, 1990; and *Chambers Science and Technology Dictionary*, W\&R Chambers Ltd and Cambridge University Press, 1988 (Allied Publishers Ltd, Bombay, Fifth Reprint 1992).
The terms defined in this part shall have a general applicability to the entire Code. Other than these, there are other terminology and definitions provided in different parts, chapters and sections which shall be applicable only to that particular part, chapter or section in which they are defined. In case of any conflict or contradiction between a definition given in this part and that in any other part, chapter or section, the meaning provided in that part, chapter or section shall govern for the interpretation of the provisions of that particular part, chapter or section. In general, definitions given in a lower level shall override the meanings of all upper levels for the interpretation of the provisions within the scope of that lower level.
## 2.2 Definitions of terms
The terminology used in this Code are defined in this section. Irrelevance of gender, tense and number is implicit in these definitions and throughout the Code. Words in the masculine gender include the feminine and the feminine the masculine. Verbs used in the present include the future. Words used in the singular include the plural and the plural the singular.
| Term | Definition |
| -------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **ACCESSORY USE** | Any use subordinate to the major use which is normally incidental to the major use. |
| **ALTERATION** | Any change, addition or modification in construction such as structural, dimensional, or any removal of any part of a building or any change to or closing of any required means of ingress or egress or a change to the fixtures or equipment or any change in land use or occupancy or use. |
| **APPROVED** | Approved by the Authority. |
| **AUTHORIZED OFFICER** | An officer appointed by the Government by notification in the Official Gazette to exercise in any area the functions of an Authorized Officer. |
| **AUTHORITY** | The Authority which has been created by a statute and which, for the purpose of administering this Code or part thereof, may authorize a committee or an official to act on its behalf. (This definition of Authority shall apply to all appearances of the term in this Code written with a capital A). |
| **BUILDING** | Any permanent or semi-permanent structure which is constructed or erected for human habitation or storage or for any other purpose and includes the foundation, plinth, walls, floors, roofs, chimneys, fixed platform, verandah, balcony, cornice, projections, extensions, annexes and any land or space enclosed by wall adjacent to it. The term building will also include the sanitary, plumbing, HVAC, outdoor display structure, signs and all other building service installations which are constructed or erected as an integral part of a building. |
| **BUILDING LINE** | The line up to which the plinth of a building may lawfully extend. Also known as SETBACK LINE. |
| **COMMITTEE** | A Building Construction Committee constituted for any area in the prescribed manner, if necessary. |
| **CONSTRUCT, TO** | See ERECT, TO. |
| **CONVERSION** | The change in occupancy or premises to any occupancy or use requiring new occupancy permit. |
| **COVERED AREA** | The ground area above the plinth level which is covered by a building structure. The covered area of a building shall exclude gardens, wells, uncovered water and swimming pool, fountains, drainage structures, boundary wall, gates, single-storey open porch, uncovered staircase, watchman's cabin, detached pump house, electrical substations, garbage chutes and other utility structures. |
| **DEVELOPMENT** | Carrying out construction of buildings, engineering, mining or other operations in, or over or under land or water. Includes redevelopment and layout and subdivision of any land. 'To develop' and other grammatical variations shall be interpreted accordingly. |
| **DRAIN** | A conduit or channel for conveying water, sewage, or other waste liquid for subsequent disposal. |
| **DRAINAGE** | The disposal of any liquid with a system meant for this purpose. |
| **ERECT, TO** | To erect a new building or re-erect an existing building or to convert a building from one occupancy to another. Also known as CONSTRUCT, TO. |
| **GOVERNMENT** | The government of the People's Republic of Bangladesh. |
| **GRADE** | The lowest point of elevation of the finished surface of the ground, pavement or footpath within the area between the building and a line which is the property line or a line 1.5 m from the building, whichever is nearer the building. |
| **HEIGHT OF BUILDING** | The vertical distance from a reference datum to the highest point of the coping or the parapet of a flat roof or to the deck line of a mansard roof or to the average height of the highest gable of a pitched or whipped roof. The reference datum shall be the elevation of the nearest footpath, or the elevation of the nearest road or street or public way at its centre line, whichever is higher. |
| **HIGH RISE BUILDING** | Any building which is more than 6 storeys or 20 m high. |
| **OCCUPANCY OR USE GROUP** | The purpose for which a building or a part thereof is used or intended to be used. |
| **OCCUPANCY, MAJOR** | The major or principal occupancy of a building or a part thereof which has attached to it subsidiary occupancy or occupancies contingent upon it. |
| **OCCUPIER** | A person paying or liable to pay rent or any portion of rent of a building in respect of which the ward is used, or compensation or premium on account of occupation of such building and also a rent-free tenant. Does not include a lodger and the words 'occupancy' and 'occupation' do not refer to the lodger. In such cases the owner himself or herself is living in his or her own building, he or she shall be deemed to be the occupier thereof. |
| **OWNER, OF A BUILDING** | The person, organization or agency at whose expenses the building is constructed or who has the right to transfer the same and includes his or her heirs, assignees and legal representatives, and a mortgagee in possession. |
| **PERMIT** | A written document or certificate issued by the Authority for carrying out a specific activity under the provisions of this Code. |
| **PLINTH AREA** | Area of a building measured at the plinth level. |
| **PLOT** | See SITE. |
| **PUBLIC WAY** | See ROAD. |
| **RELIABLE LITERATURE** | See RELIABLE REFERENCE. |
| **RELIABLE REFERENCE** | Reference materials such as published article, codes, standards or other material judged to be reliable by the professional users and specialists in the subject concerned. This may also be referred to as RELIABLE LITERATURE. |
| **ROAD** | A thoroughfare or public way which has been dedicated or deeded to the public for public use. Also known as STREET. |
| **ROAD LINE** | A line defining the side limits of a road. |
| **ROOM HEIGHT** | The clear head room between the finished floor surface and the finished ceiling surface or the underside of the joists or beams, whichever is lower. |
| **SANCTIONED PLAN** | The set of plans, design and specifications of a building submitted to the Authority as per provision of this Code and duly approved and sanctioned by the Authority. |
| **SERVICE ROAD** | A road or lane provided at the rear or side of a plot for service purposes. |
| **SETBACK LINE** | See BUILDING LINE. |
| **SITE** | A piece or parcel of land on which a building is intended to be or has already been constructed. Also known as PLOT. |
| **SPECIALIST** | A professional who by education, research, practice and experience specializes in a particular branch of a broader discipline and is generally judged to be so by the professionals in the relevant discipline. |
| **STOREY** | That portion of a building included between the upper surface of any floor and the upper surface of the floor above, except that the topmost storey shall be that portion of a building included between the upper surface of the topmost floor and the ceiling or roof above. If the finished floor level directly above a usable or unused under-floor space is more than 1.8 m above the grade, as defined herein, for more than 50 per cent of the total perimeter or is more than 3.6 m above grade at any point, such usable or unused under-floor space shall be considered as a storey. |
| **STOREY, FIRST** | The lowest storey in a building which qualifies as a storey as defined herein, except that a floor level in a building having only one floor level shall be classified as a first storey, provided such floor level is not more than 1.25 m below grade, as defined herein, for more than 50 per cent of the total perimeter, nor more than 2.5 m below grade at any point. |
| **STREET** | See ROAD. |
| **STREET LEVEL** | The elevation of the centre line of any road or street which a plot fronts. |
| **STREET LINE** | See ROAD LINE. |
| **UNSAFE BUILDING** | A building which, in the opinion of the Building Official, is structurally unsafe, or insanitary, or lacks proper means of ingress or egress, or which constitutes a hazard to life or property. |
# Chapter 3: Abbreviations
Source: https://docs.sayed.app/bnbc2006/part-1-scope-and-definitions/chapter-3-abbreviations
## 3.1 Abbreviations of names
Names of institutions, organizations and professional societies referred to in this Code are listed below in an alphabetical order.
| Abbreviation | Name |
| --------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| **ACI** | American Concrete Institute; Box 19150, Redford Station, Detroit, MI 48219, USA. |
| **AISC** | American Institute of Steel Construction, Inc.; 400 North Michigan Avenue, Chicago, IL 60611, USA. |
| **AISE** | Association of Iron and Steel Engineers; Suite 2350, Three Gateway Center, Pittsburgh, PA 15222, USA. |
| **AISI** | American Iron and Steel Institute; Suite 300, 1133 15th Street N.W., Washington, DC 20005, USA. |
| **ANSI** | American National Standards Institute; 1430 Broadway, New York, NY 10018, USA. |
| **ASHRAE** | American Society of Heating, Refrigerating and Air-conditioning Engineers, Inc.; 345 East 47th Street, New York, NY 10017, USA. |
| **ASME** | American Society of Mechanical Engineers; United Engineering Centre, 345 East 47th Street, New York, NY 10017, USA. |
| **ASTM** | American Society for Testing and Materials; 1916 Race Street, Philadelphia, PA 19103, USA. |
| **AWS** | American Welding Society; 550 N.W. LeJeune Rd., P.O. Box 351040, Miami, FL 33135, USA. |
| **BOCA** | Building Officials and Code Administrators International Inc.; 1313 East 60th Street, Chicago, IL 60637, USA. |
| **BSI** | British Standards Institution; 2 Park Street, London W1A 2BS, UK. |
| **BSTI** | Bangladesh Standards and Testing Institution; 116A Tejgaon Industrial Area, Dhaka 1208, BANGLADESH. |
| **BWDB** | Bangladesh Water Development Board; WAPDA Building, Motijheel Commercial Area, Dhaka 1000, BANGLADESH. |
| **CGSM** | Canadian General Standards Board; Technical Information Unit, Ottawa, CANADA K1A 1G6. |
| **FM** | Factory Manual; Standards Laboratories Department, 1151 Boston Providence Turnpike, Norwood, MA 02062, USA. |
| **ICBO** | International Conference of Building Officials; 5360 South Workman Mill Road, Whittier, CA 90601, USA. |
| **ISO** | International Organization for Standardization; 1, Rue de Varembé, Case Postal 56, CH-1211, Genève 20, SWITZERLAND. |
| **ISSMFE** | International Society of Soil Mechanics and Foundation Engineering; University Engineering Department, Trumpington St, Cambridge CB21PZ, UK. |
| **NFPA, NFiPA** | National Fire Protection Association; Batterymarch Park, Quincy, MA 02269, USA. |
| **PDB** | Power Development Board; WAPDA Building, Motijheel Commercial Area, Dhaka 1000, BANGLADESH. |
| **PWD** | Public Works Department; Poorta Bhaban, Segun Bagicha, Dhaka 1000, BANGLADESH. |
| **RCSC** | Research Council on Structural Connections of the Engineering Foundation; American Institute of Steel Construction (AISC). |
| **RMA** | Rubber Manufacturing Association; 1400 K Street N.W., Washington, DC 20005, USA. |
| **SBCCI** | Southern Building Code Congress International; 3617 8th Ave, S. Birmingham, AL 35222, USA. |
| **SMACNA** | Sheet Metal and Air Conditioning Contractors' National Association, 8224 Old Courthouse Road, Tysons Corner, Vienna, VA 22180, USA. |
| **SPRI** | Single Ply Roofing Institute; 104 Wilmont Road, Suite 201, Deerfield, IL 600015-5195, USA. |
| **UL** | Underwriters Laboratories, Inc; 207 East Ohio Street, Chicago, IL 60611, USA. |
## 3.2 Abbreviations of words
The abbreviations used in this Code are listed below in an alphabetical order. Abbreviations not explicitly defined herein below shall be construed to have their usual meaning as the context implies.
| Abbreviation | Meaning |
| ------------ | ------------------------------------------------------------ |
| **BDS** | Bangladesh Standards; published by the BSTI |
| **BS** | British Standard; published by the BSI |
| **CBF** | Concentric Braced Frame |
| **CFC** | Chlorofluorocarbon |
| **CGI** | Corrugated Galvanized Iron |
| **cps** | Cycles per second |
| **CWPC** | Cold Drawn Low Carbon Wire Prestressed Concrete |
| **DCP** | Dry Chemical Powder (fire extinguisher) |
| **DDT** | Dichlorodiphenyltrichloroethane |
| **DPC** | Damp-proof Course |
| **EBF** | Eccentric Braced Frame |
| **FAR** | Floor Area Ratio |
| **FM** | Fineness Modulus |
| **FPA** | Flood Prone Area |
| **GI** | Galvanized Iron |
| **IMRF** | Intermediate Moment Resisting Frame |
| **IS** | Indian Standard; published by the Bureau of Indian Standards |
| **LFD** | Load Factor Design |
| **LPG** | Liquefied Petroleum Gas |
| **MCSP** | Multipurpose Cyclone Shelter Programme |
| **OMRF** | Ordinary Moment Resisting Frame |
| **RC** | Reinforced Concrete |
| **RS** | Rolled Steel |
| **RSJ** | Rolled Steel Joist |
| **SMRF** | Special Moment Resisting Frame |
| **SPA** | Surge Prone Area |
| **SRSS** | Square Root of the Sum of the Squares |
| **UBC** | Uniform Building Code; published by the ICBO |
| **WSD** | Working Stress Design |
# Part I: Scope and Definitions
Source: https://docs.sayed.app/bnbc2006/part-1-scope-and-definitions/index
Title, purpose, and scope of the Code; definitions; abbreviations.
Part 1 sets out the Code's title, purpose, and scope; the general terms and definitions used throughout the Code; and the abbreviations of institution names and technical terms used in later parts.
## Chapters
Title, purpose, scope, existing buildings, and historic or architecturally valuable buildings.
General terms and their definitions used throughout the Code.
Abbreviations of institution and organization names, and of technical words.
# Appendix A: Forms
Source: https://docs.sayed.app/bnbc2006/part-10-signs-and-outdoor-display/appendices
Form for application for permit to erect or alter outdoor signs.
This appendix reproduces the fields of the Code's official form, referenced from Chapter 1 (Sec 1.5). The original scanned page follows the form below — right-click (or long-press) the image to save it for printing or filling in.
## Appendix A: Application for Permit to Erect or Alter Outdoor Signs
1. Type of Sign
2. Location of Sign
3. Details of Sign
* a) Dimension
* i) Length (m)
* ii) Width (m)
* iii) Thickness (mm)
* b) Clearance and Projection
* i) Clearance (m)
* ii) Projection (m)
4. Type of Materials Used
* i) Noncombustible
* ii) Approved plastic
* iii) Combination
5. Details of Electrical Installations (if any)
6. Structural details of signs and supporting structures including foundations
7. This application is accompanied by all required plans, drawings and other details as required by Sec 1.4.3 of this code.
* Yes / No
Signature of owner of the Building/Premise; Date; Name in Full; Address
Signature of Applicant; Date; Name in Full; Address
![Application Form for Permit to Erect or Alter Outdoor Signs]()
# Chapter 1: Scope and General
Source: https://docs.sayed.app/bnbc2006/part-10-signs-and-outdoor-display/chapter-1-scope-and-general
## 1.1 PURPOSE AND SCOPE
### 1.1.1
The purpose of this part of the Code is to provide minimum standards to safeguard life, health, property and public welfare by regulating and controlling the design, location, construction and maintenance of signs and outdoor display structures. The requirements of the Code cover the spatial, structural and fire safety aspects of signs located on, within or outside the building. Official traffic signs erected on roads and highways are not covered by this Code.
### 1.1.2
The regulations of this Code are not intended, and shall not be understood to permit violation of the provisions of other ordinances, regulations or official requirements in force at or near railway stations, roads, railways, terminals or other places controlled by public agencies having jurisdiction to formulate such regulations.
### 1.1.3
No sign shall be erected in any manner that would confuse or obstruct the view or interfere with official signs, signals or devices installed for the purpose of guiding or controlling the road, rail, marine or air traffic.
## 1.2 TERMINOLOGY
This section provides an alphabetical list of the terms used in and applicable to this part of the Code. In case of any conflict or contradiction between a definition given in this section and that in Part 1, the meaning specified in this part shall govern for interpretation of the provisions of this part.
**ALLEY :** Public way having a width between 2.5 m and 4 m that has been dedicated to public use.
**APPROVED PLASTIC :** Plastic materials that conform to the requirement of Sec 2.2.5.
**DISPLAY SURFACE :** The area used to display the advertising message in a sign structure.
**ILLUMINATED DISPLAY :** The display of signs with continuous or intermittent illumination of various intensity.
**MARQUEE :** A roofed structure attached to and supported by a building and projecting beyond building line or property line.
**NONCOMBUSTIBLE MATERIAL :** A material no part of which ignites or burns when subject to fire. Any material conforming to ASTM E136 shall be considered noncombustible.
**PUBLIC PASSAGE :** A public way having a width less than 2.5 m.
**PUBLIC PROPERTY :** The land property which has been dedicated or deeded to the public for use.
## 1.3 CLASSIFICATION OF SIGNS
For the purpose of this Code, and the regulations and provisions thereof, outdoor displays shall be classified into one of the following types of sign.
**BALCONY SIGN :** An advertising sign attached to, hung from or posted on a balcony or verandah of a building.
**COMBINATION SIGN :** An outdoor sign incorporating any combination of features of other signs.
**ELECTRIC SIGN :** An outdoor advertising display sign, usually animated, wired for lights or luminous tubing and containing other electric fittings, excluding those illuminated by external light source. They shall meet the requirements of the provisions of this Code governing ground, roof, wall, projecting, marquee or other sign as set forth below, depending upon where the electric signs are built.
**FIN SIGN :** An outdoor sign affixed to the wall or exterior surface of a building with the plane of the sign perpendicular to or at an angle with the building surface projecting more than 300 mm from the surface, the property line or the building line.
**GROUND SIGN :** An outdoor advertising display sign painted or otherwise displayed on the ground, supported by a pole or a structure erected independently on the ground, or mounted on a vehicle or mobile structure.
**MARQUEE SIGN :** A projecting sign attached to or hung from a marquee canopy or covered structure projecting from and supported by a building and extending beyond the building line or property line.
**PROJECTING SIGN :** An outdoor sign other than a wall sign affixed to the wall or exterior surface of a building, with the exposed face of sign in a plane parallel to the wall surface projecting more than 300 mm from the building surface, building line or property line.
**ROOF SIGN :** An outdoor sign painted on the roof surface or erected upon or above a roof or parapet of a building.
**TEMPORARY SIGN :** Any sign, banner, pendant or other display constructed of cloth, canvas, fabric, cardboard, bamboo or other light material, with or without a structural frame, intended to be displayed for a limited period only. They shall include signs on gas filled balloons afloat in the air, free or anchored to the ground or a structure, signs or words traced by smoke emitted by flying aircraft or a stationary source and signs tied to a flying aircraft.
**WALL SIGN :** An outdoor sign directly painted on or pasted or attached to or erected against the wall or exterior surface of a building, projecting not more than 300 mm from the wall.
## 1.4 APPLICATION AND PERMIT
### 1.4.1 Requirement of Permit
No sign shall be erected, re-erected, constructed, altered or maintained except as provided by this Code. A written permit shall be obtained from the Authority for all signs except those exempted from such permit in Sec 1.4.2.
### 1.4.2 Exemptions
Signs or alterations of signs described in this section and its subsections shall be exempted from the requirement of a permit. These exemptions shall not be construed as relieving the owner of the sign from the responsibility of ensuring compliance with the provisions of this Code or other regulations or laws pertaining to signs.
The following works may be undertaken on existing signs without a permit :
i) Changing of the advertisement copy or message on a painted or printed sign only. Except for cinema or theatre marquee signs or similar signs specifically designed for replaceable copy, electric signs shall not be included in this exemption.
ii) Cleaning, painting or repainting of a sign or sign structure not involving any structural alteration.
iii) Signs relating to the trade or business carried on within the premises on which such signs are displayed or notices of meeting or sale etc. to be held within the premises.
iv) Signs painted or pasted on buses or other public transport vehicles provided that no part of such signs projects beyond the body of the vehicles.
In addition, no permission shall be required for signs covered by the provisions of Sec 1.4.2.1, 1.4.2.2, 1.4.2.3 and 1.4.2.4.
### 1.4.2.1 Wall Signs
Wall signs listed below shall not require a permit :
a) Shop Signs : Signs erected over a display window or entrance of a shop or business establishment which announce the name of the shop and the business carried on provided such signs are less than 1 m in height.
b) Building Names : Wall signs erected on public or private buildings which announce the name of the establishment and the nature of occupancy .
c) Name Plates : Any wall sign less than 0.5 m² in area announcing the name and identify of the occupier.
d) Boundary Signs : Any wall sign less than 0.5 m² in area erected on boundary walls or fences surrounding the premises, or on other ornamental fences, announcing the identity of the premises.
### 1.4.2.2 Ground Signs Erected on or Visible from Highways
Ground signs erected on or visible from the highways bearing warning, cautionary, informative, identifying and temporary advertising messages of the following description shall not require a permit. When placed on highways these ground signs shall conform to the requirements of Sec 1.6.3.
a) Official warning signs, traffic directions and notices displayed on the highway by public authorities or by the requirement of a judicial order.
Examples :
| | |
| ------------- | ----------- |
| সামনে গতিরোধক | FERRY AHEAD |
b) Direction indicators to places of public service.
Examples :
| | |
| -------------- | ----------- |
| POLICE STATION | PETROL PUMP |
c) Signs bearing names of places
Examples :
| | |
| ---------- | ------------ |
| সোনার গাঁও | SHERPUR TOWN |
d) Defence warning signs.
Example :
SHOOTING RANGE
e) Private warning signs not more than 0.2 m² in area.
Examples :
| | |
| ------------ | ------------ |
| প্রবেশ নিষেধ | PRIVATE ROAD |
f) Signs not more than 0.2 m² in area placed sufficiently clear of the carriageway showing direction to a private property.
g) Signs bearing identification, direction or warning messages with respect to the premises on which they are displayed, not exceeding 0.2 m² in area.
Examples :
| | | |
| ------------ | ------------- | ----------------- |
| শান্তি কুটির | MIND THE STEP | কুকুর হইতে সাবধান |
h) Advertising signs relating to businesses, trades or professions carried out in the buildings on which they are displayed, limited to one sign not exceeding 0.3 m² in area for each business, trade or profession.
i) Identification signs relating to educational, medical, social, religious, cultural, recreational or similar institutions, hotels, blocks of flats, hostels, rest houses etc. situated on the premises on which such signs are displayed, limited to one sign not exceeding 1.2 m² in area for each such institution.
j) Temporary advertisements relating to the sale or rent of the premises on which they are displayed, limited to one sign not exceeding 2 m² in area for each sale or rent.
k) Advertisements announcing sale of goods or livestock, limited to one sign not exceeding 1.2 m² in area, displayed on the land or premises where such sale is held or goods or livestock are situated.
l) Advertisements relating to construction works in progress on the land on which the sign is displayed not exceeding 2 m² in area.
m) Signs announcing noncommercial local events of a religious, cultural, recreational or educational character, limited to a total of 0.6 m² of display on any premises on which such events are to take place.
### 1.4.2.3 Temporary Signs
Temporary signs of the following character shall not require a permit :
a) Construction site signs displaying the owner or builder's identity or the project description.
b) Special and decorative displays used for festivities, fairs, circuses, public demonstrations or promotion of civic welfare and charitable activities, provided such displays do not involve the use of electricity.
### 1.4.2.4 Other Displays
Signs displayed on the concerned premises meeting the general requirements of Table 10.1.1 and conforming with the other requirements of this Code shall not require a permit.
| **Description** | **Example** | **Number Permitted** | **Dimensional Limits** | **Maximum Size of Letters, Symbols etc.** | **Maximum Height Above Grade to Top of Sign** | **Electrification Restriction** | **Other Special Requirements** |
| ---------------------------------------------------------------------------------- | --------------------------------------------- | --------------------------------------------------------------- | ---------------------------------------------------------------------- | ----------------------------------------- | --------------------------------------------- | ------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Identification signs of public undertakings | FIRE BRIGADE | As required | As required | As required | As required | As required | - |
| Warnings, direction or identification of utilities | PATHOLOGY, NO PARKING | No limit | Maximum area 4 m² | 800 mm (400 mm in restricted sign zone\*) | 6 m (5 m in restricted sign zone) | Only for medical services and to indicate danger | - |
| Identification of company, trade, business, profession or person | KADER & CO. | One at each entrance | Maximum area 0.3 m² each | 800 mm (400 mm in restricted sign zone) | 6 m (5 m in restricted sign zone) | Only for medical services and to indicate danger | - |
| Name of building or premises | CENTRAL LAW ACADEMY, অনামিকা | One on each frontage | Maximum area 1.2 m² each | 800 mm (400 mm in restricted sign zone) | 6 m (5 m in restricted sign zone) | Only for medical services and to indicate danger | - |
| Temporary signs relating to sale or letting of property on which displayed | FOR SALE, TO LET | No restriction but total area not to exceed 2.4 m² | Width to depth ratio 2:1, total area of all signs not to exceed 2.4 m² | 800 mm (400 mm in restricted sign zone) | 6 m (5 m in restricted sign zone) | No electrification permitted | Shall not be displayed earlier than 1 month prior to date the sale or letting is due and shall be removed within 2 weeks after conclusion of sale or letting. |
| Construction site signs | SHOPPING CENTRE Consultant Contractor ....... | One for each contractor | Maximum area 4 m² | 800 mm (400 mm in restricted sign zone) | 6 m (5 m in restricted sign zone) | No electrification permitted | Permitted only while construction is in progress |
| Temporary signs announcing events displayed on the premises where these take place | বৈশাখী মেলা, কারু প্রদর্শনী | No restriction but total area not to exceed 4 m² | Maximum aggregate area 4 m² | 800 mm (400 mm in restricted sign zone) | 6 m (5 m in restricted sign zone) | Electrification shall require permission | Shall not be displayed earlier than 1 month prior to the start of event and shall be removed within 2 weeks of end of event |
| Identifying and advertising signs on business premises in restricted sign zone\* | CD BANK LTD, ABC TRAVEL | No restriction but total area not to exceed 10% of area of face | Maximum aggregate area not to exceed 10% of area of face | 400 mm | 5 m | Electrification shall require permission except for medical services and to indicate danger | - |
**Table 10.1.1** Signs Displayed on Concerned Premises which shall not Require a Permit (Sec 1.4.2.4)
* Sec 1.6.1
### 1.4.3 Application for Permit
Application for a sign permit shall be made in writing by the erector of the sign and the owner/lessee of the premises or site where the sign is to be erected on prescribed from (Appendix A). The application shall be accompanied by the following information:
a) Full specification of the sign in a sketch showing the length, height and weight of the sign, and, where applicable, number and disposition of electric lights and fittings and wiring diagram.
b) A location plan showing the position of the sign on the site, an elevation showing the sign in relation to the facade and detail drawing of the sign.
c) Detail drawings of the sign structure indicating the size of all members and the foundation and, if required by the Authority, design calculations of the structure.
d) Any other information as may be required by the Authority.
e) Required fee as may be decided by the Authority from time to time.
### 1.4.4 Condition for Grant of Permit
The grant of permit or licence to erect signs shall be subject to the following conditions :
a) An application for the grant of permit shall be made to the Authority in the manner prescribed in this Code.
b) The applicants must possess right over the property, building or premises upon which the sign is proposed to be erected either by way of ownership or by lease.
c) The permission shall be granted at any one time for a period not exceeding three years, on expiry of which the Authority shall have the right to have the sign removed at the erector's expense unless a renewal of the permit has been obtained.
d) A permit shall be renewed only upon continued satisfaction of all the conditions under which the original permit was issued.
e) The permission or the renewal of permission granted by the Authority shall become void, if
i) any addition is made to the sign structure except as may be directed by the Authority to make it secure;
ii) any change is made in the sign or part thereof, involving a change in the type of sign;
iii) any addition or alteration is made to the building which supports the sign involving disturbance of the sign or any part thereof;
iv) the sign or any part thereof falls due to accident or other causes; or
v) the building or structure supporting the sign is demolished or destroyed.
f) The Authority may, in the interest of the public, suspend the licence before expiry of the period in which case the licensee shall remove the sign forthwith.
g) The licensee shall maintain the sign and the building or structure supporting or occupied by the sign in safe, neat and sanitary condition.
h) The sign shall not, in the opinion of the Authority, mar the aesthetic beauty of the locality.
i) No sign other than that permitted by this subsection shall be allowed to obstruct or obscure building such as hospitals, public offices, educational institutions, places of worship, museums and buildings of national and historic importance.
j) No sign or boarding shall be allowed to obstruct light and ventilation of buildings situated near it.
k) No sign shall bear any objectionable, unlawful or obscene display.
l) Any boarding or sign erected on the highways shall also require the express permission of the authority or agency in charge of the highway.
m) In addition, all signs shall at all times conform to the requirements given in this Code.
### 1.4.5 Sanction or Refusal of Permit
Upon receipt of an application for permit the Authority may sanction, sanction with modification or refuse such a permit. The decision of the Authority shall be communicated within 30 days of the date of receipt of all information desired by them, failing which the permit shall be deemed to have been sanctioned. The Authority may withdraw a permit at any time in the interest of public safety and welfare.
### 1.4.6 Application for Alteration of Sign
A fresh application for permit shall be made each time the ownership of the sign changes or any change in type or structure of the sign is proposed.
### 1.4.7 Existing Signs
Signs in existence on the date of promulgation of this Code, that would otherwise require a permit, shall be exempted from the requirement of permit for a period of two years after the promulgation of the Code. On expiry of this period these signs shall require a permit as for a new sign.
## 1.5 UNSAFE AND UNLAWFUL SIGNS
### 1.5.1 Responsibility of the Owner
It shall be the responsibility of the owner to ensure the safety and legality of the sign irrespective of any reference from the Authority.
### 1.5.2 Notice of the Authority
If any sign is unlawfully installed or maintained violating any of the provisions of the Code, or if any sign becomes insecure or unsafe, the owner of the sign shall, upon written notice of the Authority, make the sign conform to the provisions of the Code or remove it, within a time period specified by the Authority which shall in no case exceed three days. If the owner fails to comply within the specified time, the Authority shall remove the sign and charge the expenses to the owner.
### 1.5.3 Prohibited Signs
Any sign, which in the opinion of the Authority, fits any of the following descriptions, shall not be permitted under any circumstances:
a) Signs of obscene, repulsive, vulgar, reveling or otherwise objectionable character,
b) Signs displaying messages prejudicial or subversive to state discipline,
c) Signs producing pernicious or injurious effect on a class of persons or the public,
d) Signs that disfigure any neighbourhood or destroy its sanctity, or
e) Signs that are likely to affect the sentiment of public.
## 1.6 RESTRICTIONS
### 1.6.1 Restricted Sign Zone
#### 1.6.1.1
The Authority may, in the interest of aesthetics, moral values or public welfare, designate an area as a restricted sign zone. Parks, playgrounds, places of historical interest, animal and bird sanctuaries, nature reserves etc. may also be designated as restricted sign zones.
#### 1.6.1.2
The erection or display of signs within the restricted sign zone shall be prohibited or restricted in any manner deemed necessary by the Authority.
#### 1.6.1.3
The wording on any sign in the restricted sign zone shall be limited to messages for identification of, direction to and information about the owner of the premises, the nature of business carried on within the premises and location of utilities and services.
#### 1.6.1.4
The restriction on signs in a restricted sign zone shall apply within a distance of 30 m outside the zone.
### 1.6.2 Prohibition of Advertisement
The erection of any advertising sign shall be prohibited on a site, when in the opinion of the Authority:
a) the site is unsuitable for display of advertising signs by virtue of the historic, cultural, architectural or similar characteristics of the locality, or
b) the display of an advertising sign is likely to pose a hazard for any form of transport.
### 1.6.3 Signs on Highways and Roads
Any advertising sign at or near highways or roads shall conform to the following requirements in addition to the requirements of the respective authority.
The item lettering skips directly from b) to d) with no item c) present; this is an anomaly in the original gazette.
a) No sign shall obscure or otherwise hinder interpretation of official traffic signs.
b) Signs on the sides of overbridges or flyovers across the carriageway shall not project beyond any edge of the parapet of the overbridge or flyover.
d) No sign shall be erected within the right of way of the road nor within 10 m of the edge of the carriageway. The size of the sign erected at 10 m away from the edge of the carriageway shall not be more than 3 m². This limit on size shall be increased by 0.3 m² for each extra metre of setback from the edge of the carriageway.
e) No sign shall be erected in such manner or at such places as to obstruct or interfere with the visibility of approaching, intersecting or merging traffic.
f) No sign shall be erected within 100 m of a bridge, railway level crossing or road junction. For urban roads this distance may be reduced to 50 m.
g) No sign shall be erected in such a way as to hinder visibility at pedestrian crossings.
### 1.6.4 Illuminated Displays
The following illuminated advertisements that threaten traffic safety shall not be permitted:
a) Illuminated or electric advertisements of such brilliance or intensity as to produce glare and impair vision of the driver and the pedestrians;
b) Advertisements containing flashing or intermittent lights of intense brightness;
c) Advertisements containing lights of such colour, disposition, brightness, movement or flashes as to obscure or reduce effectiveness of official traffic lights, signals, signs or devices.
## 1.7 MAINTENANCE AND INSPECTIONS
### 1.7.1 Maintenance
Signs and their supporting structures, together with the supports, braces, guys and anchors shall be maintained in sound condition and any deterioration shall be repaired immediately. All ungalvanized and corrosion susceptible metal components shall be painted at least once in every two years. The Authority may order removal of signs which are not maintained in proper order and such removal shall be at the owner's expense.
### 1.7.2 Inspection
Every sign shall be subject to inspection by the Authority from time to time as required by the Authority. The owner of the sign shall ensure access of the inspector and facilitate the inspection.
## 1.8 LOCATION RESTRICTIONS
An outdoor display sign shall not be erected, constructed or maintained so as to obstruct any fire escape or any window or door or opening used as a means of egress or so as to prevent free passage from one part of a roof to the other.
A sign shall not be attached in any form, shape or manner to a fire escape, nor be placed in such manner as to interfere with openings required for lighting and ventilation.
## 1.9 PROJECTION OVER PUBLIC PROPERTY
### 1.9.1
No part of a sign or sign structure shall project into a private property not owned or leased by the owner/erector of the sign, unless explicit agreement has been entered into with the owner of that property.
### 1.9.2
Signs and sign structures shall not project into public property nor into roads wider than 4 m, below a height of 2.5 m above grade, nor project more than 0.3 m when the sign is erected 2.5 m above finished grade. The signs may project 0.3 m plus 0.12 m for each 0.25 m of clearance above 2.5 m when the height is between 2.5 m and 5 m above grade. Signs may not project more than 1.5 m into a public property under any circumstance.
### 1.9.3
No sign or part thereof shall project into public passages. Projection of signs and sign structures over public alleys shall be limited to the values provided in Table 10.1.2.
| **Height Above Finished Grade (m)** | **Maximum Projection (m)** |
| ----------------------------------- | -------------------------- |
| Less than 4 | No projection permitted |
| 4 to 5 | 0.3 |
| over 5 | 0.6 |
**Table 10.1.2** Projection of Signs Over Public Alleys
## 1.10 CLEARANCE FROM POWER LINES
All signs and sign structures shall maintain the clearances from overhead electrical conductors as specified in Table 10.1.3.
| **Voltage of the Line** | **Vertical Distance (m)** | **Horizontal Distance (m)** |
| ----------------------- | -------------------------------------------------------- | --------------------------------------------------------- |
| Low and Medium Volt | 2.5 | 1.25 |
| 33 KV | 3.5 | 1.75 |
| Over 33 KV | 3.5 Plus 0.3 m for each additional 33 KV or part thereof | 1.75 Plus 0.3 m for each additional 33 KV or Part thereof |
**Table 10.1.3** Clearance from Power Lines
***
### Related Appendix
Appendix A Application for Permit to Erect or Alter Outdoor Signs
# Chapter 2: General Requirements
Source: https://docs.sayed.app/bnbc2006/part-10-signs-and-outdoor-display/chapter-2-general-requirements
## 2.1 DESIGN
### 2.1.1 Loads
All outdoor signs and sign structures shall be designed to resist wind, seismic and other forces as specified in Chapter 2, Part 6 of this Code. Combination of wind and seismic loads shall not be required. Loading that produces higher stresses shall be used.
### 2.1.2 Design Consideration
All outdoor signs and sign structures shall be designed fulfilling the design requirements as set out in Chapter 1, Part 6 of this Code.
## 2.2 CONSTRUCTION
All outdoor signs and sign structures shall be constructed and erected in accordance with the requirements of Chapter 1, Part 7 of this Code.
### 2.2.1 Use of Materials
All materials for outdoor signs and sign structures shall conform to the specification as set out in Part 5 of this Code.
### 2.2.2 Use of Combustible Materials
Ground signs not higher than 6 m may be constructed of any material that meets the requirements of this Code. No combustible material other than approved plastic as defined in Sec 2.2.5, shall be used in the construction of electric signs. Roof, wall, projecting, fin, balcony, marquee and combination signs shall be constructed of noncombustible materials except as provided below :
**a)** On roofs of combustible construction, the roof sign may be constructed of combustible materials.
**b)** On roofs of any type of construction, roof signs not higher than 1.5 m and not exceeding 5 m² in area may be constructed of combustible materials.
**c)** On walls of combustible construction, wall signs not involving the use of electricity may be constructed of combustible materials.
### 2.2.3 Anchorage
Foundation for all unbraced signs shall be designed to resist horizontal, vertical and overturning forces. All braced ground signs shall be anchored to resist the specified wind and seismic forces in any direction. Anchors shall be designed for safe soil bearing capacity and for an effective uplift force which is 25% more than the force required to resist overturning. Anchorage of signs shall not be connected to an unbraced parapet wall unless the wall is designed for seismic load.
### 2.2.4 Display Surfaces
Display surfaces of outdoor signs may be made of metal, glass or approved plastic. If the surface of the sign is made of glass, the thickness and area shall be as set forth in Table 10.2.1.
#### Table 10.2.1 Type, Size and Thickness of Glass Panels Used in Signs
| Maximum Size of Glass Panel | Minimum Thickness (mm) | Type of Glass | |
| --------------------------- | ---------------------- | ------------- | --------------------- |
| Any dimension (m) | Area (m²) | | |
| 0.75 | 0.30 | 3 | Plain, Plate or Wired |
| 1.15 | 0.45 | 5 | Plain, Plate or Wired |
| 3.65 | 2.30 | 6 | Plain, Plate or Wired |
| above 3.65 | above 2.30 | 6 | Wired Glass |
Plastic of approved type may be used for wall signs in sections not exceeding 20 m² in area. Plastics sections on wall signs shall be separated 1 m laterally and 2 m vertically. Approved plastics of unlimited area may be used on any sign other than wall sign, if approved by the Authority
### 2.2.5 Approved Plastics
Plastic materials which burn at a rate no faster than 65 mm per minute when tested in accordance with ASTM D 635 shall be deemed approved plastic. Only approved plastic shall be used for plastic display surfaces provided for in Sec 2.2.4 above. Approved plastics may also be used for ornamental purposes, decorations, lettering, facings etc. on signs and outdoor display structures.
### 2.2.6 Draining Arrangements
Signs constructed on ground or at places where possibility of accumulation of water exists shall have adequate provision for proper drainage.
## 2.3 USE OF GLASS IN SIGNS
Glass when used in outdoor signs shall be at least 3 mm thick and shall conform to the requirements of Sec 2.16.14 of Part 5 of this Code. The area of each glass panel shall not exceed 6 m² and shall be securely fixed with the frame independently. Appropriate protection against damage by falling objects shall be provided to all glass panels by metal canopies or other approved means.
## 2.4 SERVICING DEVICES
All servicing devices (ladders, platforms, hooks, rings etc.), used for cleaning, painting, repainting of sign shall have adequate safety devices and shall be of approved type and quality.
## 2.5 INTERFERENCE BY SIGNS
Signs shall not be placed at such locations that would obstruct the use of fire hydrants or other fire fighting appliances. Signs in bends and curves shall be placed in such a location so as not to obstruct the view of traffic at intersecting streets.
# Chapter 3: Specific Requirements for Various Types of Sign
Source: https://docs.sayed.app/bnbc2006/part-10-signs-and-outdoor-display/chapter-3-specific-requirements-for-various-types-of-sign
## 3.1 ELECTRIC SIGN
### 3.1.1 Materials
Materials for the construction of electric signs shall be noncombustible except as provided in Sec 2.2.2.
### 3.1.2 Location
Electric signs in colour erected at a height lower than two storeys or 6 m above the pavement shall be provided with suitable screen to avoid confusion with traffic signals. No sign in red, amber or green colours shall be erected within a horizontal distance of 10 m from any traffic signal.
### 3.1.3 Installation
All electric signs including the electrical equipment in connection with the sign shall be installed in accordance with the provisions of Part 8 Chapter 2 of this Code.
### 3.1.4 Illumination
Electric signs shall not be of such intense illumination as to cause inconvenience or disturbance to residents of adjacent buildings.
## 3.2 GROUND SIGN
### 3.2.1 Material
All ground signs over 6 m in total height shall be constructed of noncombustible materials meeting the requirements of this Code, or of approved plastics as defined in Sec 2.2.5. Materials used for the construction of ground sign supporting structures may be treated timber, masonry, concrete or corrosion resistant metal.
### 3.2.2 Height
The height of ground signs excluding the lighting reflectors shall be limited to 9 m.
### 3.2.3 Design
The design and construction of ground signs shall conform to the requirements of Parts 6 and 7 of this Code. All ground signs shall have a firm support and shall be anchored to the ground.
### 3.2.4 Clearance
All ground signs shall be provided with a clearance height of 0.6 m from the ground. The intervening space may be filled with open lattice work. Under no circumstance shall any ground sign obstruct or interfere with entrance or exit of a building.
## 3.3 ROOF SIGN
### 3.3.1 Material
All roof signs including the frames shall be constructed of noncombustible materials except as provided in Sec 2.2.2.
### 3.3.2 Design
Design and construction of roof signs shall conform to the requirements of Parts 6 and 7 of this Code. Roof signs shall be properly secured and anchored to the building and the building shall be designed to avoid overturns due to the sign.
### 3.3.3 Clearance
Roof signs shall not prevent free passage from one part of the roof to the other. Such passages shall be not less than 1 m wide and 1.25 m high.
### 3.3.4 Projection
No roof sign shall project beyond the roof in any directions.
## 3.4 PROJECTING SIGN
### 3.4.1 Material
All projecting signs and their supporting frames shall be of noncombustible material except as provided in Sec 2.2.2.
### 3.4.2 Design
The supporting frame of projecting signs and the building element to which it is anchored shall be designed to withstand, in addition to dead, live and wind loads calculated in accordance with Part 6 of this Code, appropriate loads due to servicing personnel and equipment.
### 3.4.3 Height and Clearance
A minimum of 2.5 m clearance from the road surface shall be provided for any projecting sign. The maximum height of a projecting sign shall be 15 m when affixed against buildings having a height of more than 8 storey or 36 m. For buildings 5 to 8 storeys high but not exceeding 36 m, the height of the projecting signs shall be limited to 12 m. The height of the sign shall be limited to 9 m when attached to a building less than 4 storey or 18 m high.
### 3.4.4 Projection
Projecting sign or any part of its supporting structures shall not project more than 2 m beyond the building. When such sign faces the street, it shall not project beyond the property line. Projecting sign shall not extend above the eaves of the roof of the building to which it is attached. Projection over public property or alley of projecting signs shall be limited to the values as specified in Sec 1.9.
### 3.4.5 Attachment
All projecting signs shall be so constructed or attached to the building that movement in any direction is prevented by rods, anchors, brackets, chains etc.
## 3.5 FIN SIGN
### 3.5.1 Material
Materials for fin sign shall conform to the requirements of Sec 2.2.2.
### 3.5.2 Design
Design and construction of fin signs shall conform to the requirements of Parts 6 and 7 of the Code.
### 3.5.3 Clearance
Fin signs shall not obstruct windows and reduce light and ventilation to such a point as the Code or other regulations prohibit. Such signs and their frames shall not obstruct fire escape, exit and entrance of the building to which they are attached. Projection of fin signs over public property shall conform to the requirements of Sec 1.9.
## 3.6 BALCONY SIGN
### 3.6.1 Materials
Materials for balcony signs shall conform to the requirements of Sec 2.2.2.
### 3.6.2 Location
Balcony signs shall be placed above the eaves of the balcony and shall not project beyond the rear of the roof gutter.
### 3.6.3 Size
The height of a balcony signs shall be limited to 1 m. Hanging balcony sign shall not exceed 2.5 m in length and 50 mm in thickness. For hanging box type signs the maximum allowable depth shall be 200 mm.
### 3.6.4 Projection
Balcony signs shall not extend beyond the balcony line. Hanging balcony signs shall maintain a clearance height of 2 m from the finished ground level. Projection of balcony sign over public property or alley shall be limited to values as specified in Sec 1.9.
## 3.7 MARQUEE SIGN
### 3.7.1 Materials
Materials for the construction and erection of marquee signs shall conform to the requirements of Sec 2.2.2.
### 3.7.2 Size
The height of a marquee sign shall be limited to 2 m. The length of such sign may be equal to the length of the marquee and no projection beyond the full length shall be allowed.
### 3.7.3 Clearance
A clearance height of at least 2.5 m shall be provided for marquee signs.
## 3.8 COMBINATION SIGN
All combination signs shall meet the general and specific requirements of all the component classes of sign.
## 3.9 TEMPORARY SIGN
### 3.9.1 Size
The area of a temporary sign shall not ordinarily exceed 10 m². Temporary signs of a larger area may be erected upon explicit approval of the Authority which shall only be granted, for signs of a duration not exceeding 7 days. Temporary signs made of rigid material shall not exceed 3 m² in area, nor shall they have a height more than 2 m. Such rigid signs shall be anchored to the ground or a building by a rigid structure.
### 3.9.2 Duration
Temporary signs shall be removed from the location within 60 days of first erection, unless explicit permission of the Authority for extending this period has been obtained. In no case a temporary sign shall be permitted to be maintained for more than 90 days.
### 3.9.3 Support
Temporary signs shall be adequately supported and secured in place. No part of the sign shall be permitted to dangle, sway or otherwise become loose or detached. In order to reduce wind resistance on signs made of fabric, adequate perforations shall be provided.
### 3.9.4 Location
All temporary signs shall be subject to the approval of the Authority and shall be erected in such a place so as not to obstruct any public way, foot path or entrance and exit of any building.
### 3.9.5 Projection
Temporary cloth sign may extend over public property. A clearance of 6 m shall be maintained when such signs are placed over a public street. Other temporary signs when placed 2.5 m above the ground may project not more than 300 mm over public property or beyond the legal set back line.
# Part X: Signs and Outdoor Display
Source: https://docs.sayed.app/bnbc2006/part-10-signs-and-outdoor-display/index
Scope, general requirements, and specific requirements for various types of sign.
Part 10 covers signs and outdoor display: scope and general provisions, general design and construction requirements, and requirements specific to individual sign types.
## Chapters
Purpose, scope, terminology, sign classifications, and restrictions.
Design, construction, materials, and servicing requirements for signs.
Requirements by sign type: ground, roof, projecting, fin, balcony, and temporary signs.
## Appendices
Form for application for permit to erect or alter outdoor signs.
# Appendices A-D: Forms
Source: https://docs.sayed.app/bnbc2006/part-2-administration-and-enforcement/appendices
Forms for application, certificate of supervision, sanction or refusal of permit, and completion certificate.
These appendices reproduce the fields of the Code's official forms, referenced from Chapter 3 (Sec 3.2.1, Sec 3.2.3.9, Sec 3.2.10.1, and Sec 3.3.4). Each form in the source document is addressed to the Building Official at the position and address applicable to the local jurisdiction. The original scanned page follows each form below — right-click (or long-press) the image to save it for printing or filling in.
## Appendix A: Form for First Application to Develop, Erect, Demolish or to Make Alteration in any Part of the Building
Type of intended work (check one): Develop / Erect / Demolish / Alter
* Name of the owner
* Contact address
* Post code
* Telephone no.
Name, address and qualification of the engineer, architect or planner involved in the proposed work:
* For planning
* For architectural design
* For structural design
* For civil works design
* For other services design
Address of the site:
* Plot number
* Holding number
* Dag/Khatian number
* Mouza/Block/Sector
* Street name
* Municipal ward number
Documents enclosed along with this form (name of document, number of sheets, number of copies):
1. Key plan
2. Site plan
3. Subdivision/layout plan
4. Building plan
5. Services plan
6. Specifications
7. Ownership title
Date; Signature of the owner.
*For use of the Building Official. Do not write anything below this line.*
Reference number (to be referred to in all subsequent correspondences); Date; Received by.
![Form for First Application to Develop, Erect, Demolish or to Make Alteration in any Part of the Building]()
## Appendix B: Form for Certificate of Supervision
* Reference number
* Address of the site (plot number, holding number, street name, municipal ward number)
Type of intended work (check one): Develop / Erect / Demolish / Alter
* Name of the owner
* Contact address
* Post code
* Telephone no.
"I hereby certify that the building for which the location, the type of work, and the name and address of owner appear above will be supervised by me as per the provisions of the Bangladesh National Building Code."
Signature of the engineer, architect, planner or supervisor; Name; Address; Qualification; Date.
![Form for Certificate of Supervision]()
## Appendix C: Form for Sanction or Refusal of Development/Building Permit
Reference number.
"In response to your application whose reference number appears above, I hereby inform that the documents submitted along with your application have been (check as appropriate)"
* Approved for implementation by the Authority
* Refused by the Authority for violation of the following provisions of the Bangladesh National Building Code: *(list of the sections violated)*
Signature of the Officer; Name of the Officer; Designation; Permit number; Official stamp; Date.
![Form for Sanction or Refusal of Development/Building Permit]()
## Appendix D: Form for Completion Certificate
* Reference number
* Permit number
* Address of the site (plot number, holding number, dag/khatian number, mouza/block/sector, street name, municipal ward number)
* Documents enclosed along with this form
Type of work (check one): Develop / Erect / Demolish / Alter
* Name of the owner
* Contact address
* Post code
* Telephone no.
"I hereby certify that the work having the above mentioned detailed particulars has been supervised by me and completed in accordance with the plan and design approved by the permit number cited and the provisions of the Bangladesh National Building Code."
Signature of the engineer, architect, planner or supervisor; Name; Address; Qualification; Date. Signature of the owner; Date.
*This part to be completed by the Building Official.*
"The work identified by the reference number and permit number at the top of the form is hereby accepted as complete in accordance with the approved plan and design."
Signature of the Officer; Name of the Officer; Designation; Official stamp; Date.
![Form for Completion Certificate]()
# Chapter 1: Purpose and Scope
Source: https://docs.sayed.app/bnbc2006/part-2-administration-and-enforcement/chapter-1-purpose-and-scope
## 1.1 Purpose
The purpose of this part is to specify the provisions for administration and enforcement of the Code.
## 1.2 Scope
This part of the Code sets forth the administrative procedure for enforcement of the provisions thereof. The applicability of the Code, provision for designating a Building Official, powers and duties of such Building Official, obligations and liabilities of engineers, architects or planners, provisions against violation of the Code and procedure for obtaining building permits are specified in this part.
## 1.3 Terminology
This section provides an alphabetical list of the terms used in and applicable to this part of the Code. In case of any conflict or contradiction between a definition given in this section and that in Part 1, the meaning specified in this section shall govern for interpretation of the provisions of this part.
| Term | Definition |
| ------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **ALTERATION** | Any change, addition or modification in construction such as structural, dimensional, or any removal of any part of a building or any change to or closing of any required means of ingress or egress or a change to the fixtures or equipment or any change in occupancy or use. |
| **APPLICANT** | A person, a firm, a company, a corporation, or a government, semi-government or non-government agency who intends to undertake any work regulated by this Code and who has filed an application to the Building Official for this purpose in a form prescribed in the Code. |
| **APPROVED PLAN** | The set of plans, designs and specification of a building submitted to the Authority as per provision of this Code and duly approved and sanctioned by the Authority. |
| **AUTHORIZED OFFICER** | An officer appointed by the Government by notification in the Official Gazette to exercise in any area the functions of an Authorized Officer. |
| **BUILDER** | A person, a firm, a company, a corporation or a government, semi-government or non-government agency who undertakes construction of any work regulated by the Code. Owner of a building or structure in connection to which the work is undertaken shall not be considered as a Builder. |
| **CONSTRUCT, TO** | To construct a new building or reconstruct an existing building or to convert a building from one occupancy to another. |
| **DEVELOPMENT** | Carrying out construction of buildings, engineering, mining or other operations in, or over or under land or water. Includes redevelopment and layout and subdivision of any land. 'To develop' and other grammatical variations shall be interpreted accordingly. |
| **ERECT, TO** | See CONSTRUCT, TO. |
| **OWNER (OF A BUILDING)** | The person, organization or agency at whose expenses the building is constructed and who has the legal right over the land on which it is constructed or one who has the right to transfer the same and includes his or her heirs, assignees and legal representatives, and a mortgagee in possession. |
| **PERMIT** | A written document or certificate issued by the Authority for carrying out a specific activity under the provisions of this Code. |
| **UNSAFE BUILDING** | A building which, in the opinion of the Building Official, is structurally unsafe, or insanitary, or lacks proper means of ingress or egress, or which constitutes a hazard to life or property. |
## 1.4 Applicability
The requirements of this Code shall be complied within any construction, addition, alteration or repair, use and occupancy, location, maintenance, demolition and removal of a building or structure or any appurtenances connected or attached to it as set forth herein below.
### 1.4.1 Construction
For construction of a new building, the provisions of this Code shall apply to its design and construction.
### 1.4.2 Removal
For removal of any portion or the whole of a building, the provisions of this Code shall apply to all parts of the building whether removed or not.
### 1.4.3 Demolition
For dismantling or demolition of any part or the whole of a building, the provisions of this Code shall apply to any remaining portion and to the work involved in the dismantling or demolition process.
### 1.4.4 Alteration
For alteration of a building, the provisions of this Code shall apply to the whole building whether existing or new. If the portion of the building to which the alteration is made is completely self contained with respect to the facilities and safety measures required by this Code, the provisions of this Code shall apply only to that portion and not to the whole building.
### 1.4.5 Maintenance
Maintenance work shall be undertaken for all new and existing buildings and all parts thereof to continue their compliance with the provisions of this Code. All devices, equipment and safeguards installed as per the requirements of this Code shall be maintained in conformity with the edition of the Code under which installed. The owner of the building or his designated agent shall at all times be responsible for the safe and sanitary maintenance of the building or structure, its means of egress facilities and the safety devices, equipment and services installed therein. The Building Official may cause reinspection of a building to determine its continued compliance with this section.
### 1.4.6 Repair
Application or notice to the Authority administering the Code is not necessary for ordinary repairs to buildings or structures, provided such repairs do not involve the cutting away of any wall or portion thereof, the removal or cutting of any structural or bearing element, the removal or alteration of any required means of egress, or the rearrangement of any parts of a structure affecting the access and exit facilities. All works involving addition to, alteration or change of use of any building or structure shall conform to the requirements set forth in Part 9 of this Code.
### 1.4.7 Land Development
For development of a land for construction of a building, the provisions of this Code shall apply to the entire development work.
## 1.5 Alternative provisions
### 1.5.1 Approval
The provisions of this Code are not intended to prevent the use of any material or method of construction not specifically prescribed herein provided such alternative material or method has been approved and its use authorized by the Building Official.
Such alternative may be approved by the Building Official provided the Building Official finds that the proposed design is in compliance with the provisions of this Code and that the material and the method of work and construction proposed for the intended work ensure at least the same level of suitability, strength, effectiveness, fire resistance, durability, safety and sanitation as that required by the provisions of this Code.
Whenever any such alternative is proposed, the Building Official shall require that sufficient evidence or proof be submitted to substantiate any claims that may be made regarding its use. The Building Official shall record the details of any action granting approval of any such alternative.
Whenever any new material or method of construction not specified in this Code, and for which sufficient evidence of compliance with the provisions of this Code is not available, is proposed to be used, the Building Official may require tests to be carried out as a proof of compliance with the provisions of this Code at the expense of the owner of a building or structure for which such alternate is proposed.
Tests shall be carried out as specified in this Code or by other recognized test standards. If for any test there is no provision in this Code or there is no recognized and accepted test method, the Building Official shall determine the test procedure.
Tests shall be performed by an approved agency and the reports thereof shall be retained by the Building Official for the period required for the retention of public records.
### 1.5.2 Modifications
Modifications may be granted for individual cases by the Building Official, with the approval of the Authority, when there are practical difficulties in carrying out the provisions of this Code provided that:
i) There is a special individual reason found in the opinion of the Building Official that makes strict adherence to this Code impractical;
ii) The modifications do not lessen any fire protection requirements or any degree of structural integrity; and
iii) The modifications are in conformity with the intent and purpose of this Code.
The Building Official shall record any action regarding granting of such modifications for future reference of the Code enforcing agency.
# Chapter 2: Organization and Enforcement
Source: https://docs.sayed.app/bnbc2006/part-2-administration-and-enforcement/chapter-2-organization-and-enforcement
## 2.1 Code enforcement agency
The Government shall establish a new or designate an existing agency responsible for enforcement of this Code with a given area of jurisdiction. For the purpose of administering and enforcing the provisions of this Code the code enforcing agency shall have the authority of the government and shall herein be referred to as the Authority.
### 2.1.1 Building Official
The administrative and operational chief of the code enforcing agency shall be designated as the Building Official who shall act on behalf of the Authority. The Building Official may designate an employee or employees who shall carry out the specified duty and exercise the specified power of the Building Official.
### 2.1.2 Merging the Jurisdictions under Small Local Bodies
Small local bodies like pourashavas and thanas located outside the larger city municipalities and having insufficient funds for individually carrying out the task of a code enforcing agency may jointly appoint or designate, with the approval of the authority, a Building Official who shall have a jurisdiction over the combined area of jurisdiction of the concerned local bodies.
### 2.1.3 Organization
The Building Official shall appoint such number of officers, technical assistants, inspectors and other employees as shall be required for proper administration of the Code and as authorized by the Authority.
### 2.1.4 Qualification of the Building Official
The person to be designated as the Building Official shall be at least an engineer, architect or planner in addition to fulfilling any other requirement of the Authority. The employees of the Building Official shall be adequately qualified to carry out the responsibilities assigned to them by the Building Official.
### 2.1.5 Restrictions on the Building Official
The Building Official or any of his employees shall not in any way, directly or indirectly, be engaged in planning, design, construction, repair, maintenance, modification or alteration of a building, certification of any work or materials, supply of materials, labour, equipment or appliances or any other work regulated by the provisions of this Code. The Building Official or any of his employees shall not be interested in business, either directly or indirectly, as planner, engineer, architect, builder or supplier or in any other private business transaction or activity within the jurisdiction of the Authority which conflicts with his official duties or with the interest of the code enforcing agency.
### 2.1.6 Damage Suit
In the process of discharging the official duties as required and permitted by the Code, the Building Official or any of his employees shall not be personally liable for any damage that may be caused to any person or property. Any suit filed against the Building Official or any of his employee because of an act performed by him in the official discharge of his duties and under the provisions of the Code shall be defended by the legal representative of the Authority until the final decision of the proceedings. In no case shall the Building Official or any of his employees be liable for costs in any legal action, suit, or defence proceeding that may be filed in pursuance of the provisions of the Code.
## 2.2 Powers and duties of the Building Official
### 2.2.1 General
The Building Official shall be authorized to enforce all the provisions of this Code and for such purposes the Building Official shall have the power of a law enforcing officer.
The Building Official shall be authorized to interpret this Code and to adopt and enforce rules and supplemental regulations in order to clarify the application of its provisions in conformity with the intent and purpose of this Code.
### 2.2.2 Deputies
The Building Official may appoint such number of technical officers and inspectors and other employees as shall be authorized from time to time in accordance with the prescribed procedures and with the approval of the Authority.
The Building Official may designate such officers or inspectors as may be necessary to carry out the functions of the code enforcement agency.
### 2.2.3 Recognition of Professional Services
The Building Official may recognize the professional services provided by engineers, planners, architects and supervisors. Such recognition may be withdrawn by the Building Official under the provisions set forth in Sec 2.6.3.
### 2.2.4 Application and Permits
Applications shall be made in writing to the Building Official for any erection, construction, addition, alteration, modification, repair, improvement, removal, conversion or demolition of any building or structure regulated by this Code. The Building Official shall receive such applications, examine the premises, enforce compliance with this Code and issue permits for the intended work.
### 2.2.5 Building Notices and Orders
All necessary notices and orders to correct illegal or unsafe conditions, to require the specified safeguards during construction, to require adequate access and exit facilities in existing buildings and to ensure compliance with all the requirements of safety, health and general welfare of the public as included in this Code shall be issued by the Building Official.
### 2.2.6 Right of Entry
The Building Official may enter a building or premises at reasonable times to inspect or to perform the duties imposed by this Code if:
i) it is necessary to make an inspection to enforce the provisions of this Code; or
ii) the Building Official has reasonable cause to believe that a condition contrary to or in violation of this Code exists making the building or the premises unsafe, hazardous or dangerous.
If the building or premises is occupied, the Building Official shall present credentials to the occupant and request entry. If the building or premises is unoccupied, the Building Official shall first make a reasonable effort to locate the owner or any other person having charge or control of the building or premises and request entry. If entry into the building or premises is refused or the owner of the unoccupied building or premises cannot be located, the Building Official shall secure entry as provided by the law.
### 2.2.7 Inspection
The Building Official shall inspect all construction or work for which a permit is required or he shall accept reports of inspection by an engineer, architect or planner and may approve or disapprove the work inspected. The work or construction to be inspected shall remain accessible and exposed for inspection purposes until the approval is obtained.
All reports of inspection shall be in writing and certified by the Building Official or the engineer or the architect making the inspection.
Approval of work or construction as a result of such inspection shall not be interpreted to be an approval of a violation of the provisions of this Code or of other ordinances of the jurisdiction.
The Building Official may require survey of the site and adjoining areas to verify that the structure is located in accordance with the approved plans.
### 2.2.8 Orders to Stop Work
The Building Official may issue an order for immediate discontinuation of a work and cancellation of a previous permit for such work at any stage if:
i) any work is being done contrary to the provision of this Code or other pertinent laws or ordinances implemented through the enforcement of this Code; or
ii) it is determined by the Building Official that the construction is not proceeding according to the approved plan.
In such cases the Building Official shall notify the owner in writing of such an order and all further construction shall be stayed until correction has been effected and approved.
### 2.2.9 Occupancy Violation
The Building Official may order the current uses of a building discontinued and the building or portion thereof vacated by serving a notice on any person if the Building Official determines that the building or structure or equipment therein regulated by this Code is being used contrary to the provisions of this Code. Such person shall discontinue the use within the time prescribed by the Building Official after receipt of such notice to make the structure, or portion thereof, comply with the requirements of this Code.
### 2.2.10 Maintenance of Records
The Building Official shall maintain records of all applications and drawings received, permits and orders issued, inspections made and reports prepared and submitted by other recognized agencies. Copies of all relevant papers and documents for enforcement of the Code shall be preserved by the Building Official. All such records shall be kept open to public inspection at all suitable times.
### 2.2.11 Expert Opinion
The Building Official may engage, subject to the approval of the Authority, an expert or a panel of experts for opinion on unusual technical issues that may arise in administering the provisions of the Code.
## 2.3 Board of Appeals
There shall be a Board of Appeals to hear and decide appeals of orders, decisions or determinations made by the Building Official related to the application and interpretation of this Code. The Board of Appeals shall provide reasonable interpretation of the provisions of this Code and determine the suitability of alternative materials or methods of design or construction. Such Board shall consist of members appointed by the Authority who are noted for their education and experience in the relevant field of building construction and whose term of office shall be at the pleasure of the Authority. The Building Official shall be the ex-officio nonmember secretary of the Board without having any voting power before the Board.
The Board shall, with the approval of the Authority, adopt rules of procedure for conducting its business, and shall communicate all decisions and findings in writing to the appellant with a copy to the Building Official.
The Board of Appeals shall have no authority for interpretation of the administrative provisions contained in Part 2 of this Code nor shall the Board be empowered to waive any requirement of this Code.
## 2.4 Requirement of certification of work
Any planning, design, supervision of construction, repair, maintenance, modification and alteration of buildings, or any other work regulated by the Code shall be certified by an engineer, architect or planner for its compliance with the provisions of the Code.
## 2.5 Limits of professional conduct
An engineer, architect or planner assisted if necessary by personnel working under his direct control, shall be allowed to plan, design and supervise construction, repair, maintenance, alteration and modification of buildings or structures regulated by this Code provided he certifies compliance of the work with the provisions of the Code. Such a person may provide any such certificate as long as his or her services are recognized by the Building Official as specified in Sec 2.2.3 and such recognition is not withdrawn under the provisions of Sec 2.6.3.
## 2.6 Violation and penalties
### 2.6.1 General
Any person, firm, corporation or government department or agency who as owner of the property erects, constructs, enlarges, alters, repairs, moves, improves, removes, converts, demolishes, equips, uses, occupies or maintains any building or structure or cause or permit the same to be done in violation of this Code shall be guilty of an offence and the Authority shall take legal action against such offenders. The term owner shall, for the purpose of these provisions include any developer who by appointment, contract or lease is or has been responsible for the actions listed above.
### 2.6.2 Height Control near Aerodromes
If any building or structure violates the height limitation imposed by the Civil Aviation Authority near aerodromes, it shall be demolished at the expense of the owner and reduced to bring it to a level within the permissible height.
### 2.6.3 Professional Violation
The engineer, architect or planner responsible for design, supervision or certification of any construction or other work of a building or structure shall ensure compliance of such work with the provisions of this Code, any violation of which or any other professional misconduct insofar as implementation of the provisions of this Code is concerned including making false statements or issuing false certificates or any incidence of proven professional incapability shall make him liable to penalties as prescribed by the Authority including withdrawal of recognition.
### 2.6.4 Obligation of Offender
A person shall not be relieved from the duty of carrying out the requirements or obligations imposed on him or her by virtue of the provisions of this Code even if such person is convicted for an offence under the provisions of this section.
### 2.6.5 Conviction No Bar to Further Prosecution
If a person is convicted under the provisions of this Code for failing to comply with any of its requirements or obligations such conviction shall not act as a bar for further prosecution for any subsequent failure on the part of such person to comply.
## 2.7 Power to make rules
The Authority may make rules for carrying out the provisions and intentions of this Code. Such rules shall not contradict nor nullify any of the provisions of this Code. The Authority may fix and refix from time to time application fees for issuance of permits for all works under the provisions of this Code.
# Chapter 3: Permits and Inspections
Source: https://docs.sayed.app/bnbc2006/part-2-administration-and-enforcement/chapter-3-permits-and-inspections
## 3.1 Permits
### 3.1.1 Requirement of Permit
No building or structure regulated by this Code shall be erected, constructed, enlarged, altered, repaired, moved, improved, removed, converted or demolished without first obtaining a separate permit for each such work from the Building Official.
**Exceptions:**
The following works are exempted from the requirement of a permit unless they do not otherwise violate any provisions of this Code, for the said work or any other adjacent property, regarding general building requirements, structural stability and fire safety requirements of this Code:
i) Opening or closing of a window or a door or a ventilator;
ii) Providing internal doors;
iii) Providing partitions;
iv) Providing false ceiling;
v) Gardening;
vi) Painting;
vii) Retiling and reroofing;
viii) Plastering and patch work;
ix) Reflooring;
x) Construction of sunshades on one's own land;
xi) Re-erection of portion of buildings damaged by earthquake or cyclone or other natural calamities, to the extent and specification as existed prior to such damage; and
xii) Solid boundary walls less than 1.5 m and open boundary wall less than 2.75 m in height.
### 3.1.2 Permits Obtained Prior to Adoption of Code
If permit for a building or structure or a work regulated by this Code is obtained before adoption of this Code and the building or structure or work for which the permit is obtained is not completed within three years from the date of issuance of such permit, the said permit shall be deemed to have lapsed and fresh permit shall be necessary to proceed further with the work in accordance with the provisions of this Code.
## 3.2 Application for permit
### 3.2.1 Application
Any person who intends to undertake any work on a building or structure or land regulated by this Code shall first file an application therefor in writing on a form furnished by the Building Official for that purpose (see Appendix A). Such applications shall be accompanied by plans and statements in seven copies as required by the provisions of this section.
### 3.2.2 Operation and Maintenance of Utility Services
The Government may undertake works for operation, maintenance, development or execution of any of the following utility services without requiring to obtain permit from the Building Official:
i) Railways;
ii) National highways;
iii) National waterways;
iv) National gas grid;
v) National power grid;
vi) Major ports;
vii) Airways and aerodromes;
viii) Posts and telegraphs;
ix) Telecommunications;
x) Radio, TV and other similar broadcasting services; and
xi) Any other service which the Government may, by notification, declare to be a service for the purpose of this section if the Government is of the opinion that the operation, maintenance, development or execution of such service is essential to the community.
Buildings constructed in connection with these services shall conform with the specifications of this Code.
### 3.2.3 Information Accompanying the Application
#### 3.2.3.1 General
Application for permit of any work under the provisions of this Code shall be accompanied by a key plan, a site plan, a building plan, services plans, specifications and certificate of supervision as specified in this section. The drawings shall have any of the sizes specified in Table 2.3.1. All plans and drawings shall be signed by an architect or planner or engineer which shall be considered as equivalent to certifying that the plan on which the signature appears conforms to all the requirements of this Code.
**Table 2.3.1 — Sizes of Drawing Sheet**
| Notation (ISO Standard) | Trimmed Size (mm) | Untrimmed Size (mm) |
| ----------------------- | ----------------- | ------------------- |
| A0 | 841 x 1189 | 880 x 1230 |
| A1 | 594 x 841 | 625 x 880 |
| A2 | 420 x 594 | 450 x 625 |
| A3 | 297 x 420 | 330 x 450 |
| A4 | 210 x 297 | 240 x 330 |
| A5 | 148 x 210 | 165 x 240 |
#### 3.2.3.2 Key Plan
A key plan of the site shall be submitted along with the application which shall:
i) have a scale of 1:10,000 or larger; and
ii) show the boundaries of the site with respect to neighbouring landmarks.
#### 3.2.3.3 Site Plan
The site plan to be submitted with the application shall have a scale of not less than 1:500 for a site of up to 1 ha and not less than 1:1000 for a site greater than 1 ha. The site plan shall contain the following information:
i) A north arrow and a scale factor or scale bar;
ii) The boundaries of the site and the neighbouring streets along with their dimensions and names;
iii) All existing buildings, structures or service lines on, above, below or surrounding the site;
iv) The position of the proposed building and of all other buildings on the site with respect to the boundaries of the site and of any subdivision thereof if applicable, and all adjacent buildings (with number of storeys and height) and premises within a distance of 12 m of the site;
v) The means of access from the street to the building which the applicant intends to construct and to all other buildings upon the site;
vi) Space to be left open around the building; and
vii) Any physical features, such as wells, drains etc.
#### 3.2.3.4 Application for Development Works
Applications for permit for a development work shall be accompanied by a subdivision or layout plan drawn on a scale of 1:500 or greater and containing the following information:
i) A north arrow and a scale factor or scale bar;
ii) The location of all proposed and existing roads and their dimensions;
iii) Dimensions of the plots, the building lines and setbacks;
iv) The location of utility services like drains, sewers, electric lines and gas lines;
v) The identification number, size, dimensions and use of all the plots in a tabular form;
vi) Information in a summary form indicating the total area of the site, area utilized under roads, open spaces for parks, playgrounds, recreation spaces, schools, shopping centres, community centres and other public places; and
vii) The means of access to each subdivision of the site.
#### 3.2.3.5 Building Plan
The building plans accompanying the application shall have a scale of not less than 1:100 and shall contain the following information:
i) A north arrow and a scale factor or a scale bar;
ii) Floor plans of all floors together with the covered area clearly indicating the size and spacing of all framing members and sizes of rooms and the position of staircases, ramps and lift wells;
iii) Use or occupancy of all parts of the buildings;
iv) Location of all utility services;
v) Sections showing clearly the sizes of the footing, thickness of basement wall, wall construction, size and spacing of the framing members, floor slabs and roof slabs with their materials, height of the rooms and parapets, drainage and slope of the roof and terrace (if any), and details of the staircase.
vi) Street dimensions and elevations; and
vii) All projected portions of the building.
#### 3.2.3.6 Building Plans for Multi-storeyed and Other Special Buildings
Applications for any work under the provisions of this Code involving buildings higher than 20 m and other buildings like educational, assembly, institutional, industrial or hazardous and mixed occupancies with any of the aforesaid occupancies having an area of more than 500 m² shall be accompanied with the following information as may be applicable in addition to those specified in Sec 3.2.3.5:
i) Accessibility of fire appliances and vehicles with details of vehicular turning circle and clear motorable passage around the building;
ii) Location and dimensions of alternate stairway along with any approach thereof;
iii) Location and details of lift enclosures;
iv) Location and dimensions of fire escape;
v) Smoke stop lobby or door;
vi) Refuse chutes, refuse chamber and service duct;
vii) Vehicular parking spaces and vehicle movement and parking plan;
viii) Refuse area;
ix) Details of building services like air-conditioning, mechanical ventilation system, electrical services, boiler and gas pipes;
x) Details of exits;
xi) Location of generator, transformer and switch gear room;
xii) Smoke exhaust system;
xiii) Fire alarm system;
xiv) Location of centralised control, connecting all fire alarm systems, built-in fire protection arrangement and public address system etc.;
xv) Location and dimensions of static water storage tank and pump room along with fire service inlets for mobile pump and water storage tank;
xvi) Location and details of fixed fire protection installations such as sprinklers, wet risers, hose reels, drenchers, CO2 installations etc.; and
xvii) Location of first aid arrangements.
#### 3.2.3.7 Plans of Services
The plans showing utilities to the buildings such as gas, water, electricity, drainage and sewage disposal system shall include all details of such systems within the building and their interface with the street network of the concerned agency.
#### 3.2.3.8 Specifications
Specification of the materials to be used in the building or structure shall be specified in sufficient detail to enable the Building Official to check conformity of such specifications with the provisions of this Code.
#### 3.2.3.9 Supervision of Work
The application shall be accompanied by a certificate of supervision in the form as prescribed in Appendix B by an engineer, architect, planner or supervisor of relevant field.
#### 3.2.3.10 Requirement of Additional Information
The applicant shall provide any other information required by the Building Official to determine conformity with the provisions of this Code.
### 3.2.4 Preparation and Signing of Plans
All plans shall be prepared under the guidance of an engineer, architect or planner as may be applicable who shall put his or her signature with date on the title block of the plans along with his name, address and degree. The plans shall also contain the signature, name and address of the owner.
### 3.2.5 Notice for Land Adjoining Government or Corporate Bodies Formed Under the Statute
Application and the accompanying plans for any work or development under the provision of this Code on any site adjoining any Government land or property shall be prepared and submitted in sufficient numbers to enable the Building Official to forward one set each to the appropriate Government agency or agencies for report before permission is granted. The concerned Government agency shall report to the Building Official whether or not they have any objection to the proposed work within two weeks from the date of receipt of the application and plans. If no such report is received within two weeks by the Building Official the concerned Government agency shall be deemed to have no objection to the execution of the proposed work. In case any government agency have any objection to a proposed work, such objection shall be stated with definite reasons.
### 3.2.6 Fees
All applications shall be accompanied by fees as specified by the Building Official from time to time without which the application shall be deemed to be incomplete.
### 3.2.7 Duration of Permit
Works for which permit has been obtained under the provisions of this Code shall be valid for a duration of 5 years. For projects of exceptionally large magnitude the Building Official may extend the duration of such permit. On expiry of a permit, the owner shall obtain a fresh permit which may be granted by the Building Official on satisfaction of the provisions of the version of the Code in force at that time.
### 3.2.8 Deviation from Approved Plan
Deviations from the approved plans may be permitted provided such deviation is notified to the Building Official before undertaking the related work and approval is obtained for the deviation. The revised plan showing the deviations shall be submitted and the procedure specified for the original plan heretofore shall apply to all such amended plans.
**Exception:**
The works specified in Sec 3.1.1 as exceptions shall be exempted from the requirements of obtaining permits from the Building Official unless they do not otherwise violate any provisions of this Code regarding general building requirements, structural stability and fire safety requirements of this Code.
### 3.2.9 Cancellation of Permit
The Building Official shall have the authority to cancel any permit issued previously under the provisions of this Code if there is any false statement or any misrepresentation of any material fact in the application on the basis of which the permit was issued, or there is any deviation from the approved plans without any prior approval of the Building Official.
### 3.2.10 Granting or Refusal of Permit
#### 3.2.10.1 General
The Building Official may either grant or refuse permit to an applicant for carrying out the intended work (see Appendix C).
#### 3.2.10.2 Multi-storeyed and Other Special Buildings
In case of applications for works related to buildings as specified in Sec 3.2.3.6, all relevant drawings and other information shall be subject to scrutiny of the fire authority and their approval shall be necessary for approval of the plan by the Building Official.
#### 3.2.10.3 Time Limit
The Building Official shall notify the applicant within 60 days from the date of receipt of an application and all other information required by him of either approval or refusal of the permit for any work. If the Building Official does not notify the applicant of such approval or refusal within this specified period, the plans shall be deemed to have been approved provided the fact is brought to the notice of the Building Official. Such approval shall not be interpreted to authorize any person to do anything in contravention of or against the terms of lease or titles of the land or against any other regulations, bylaws or ordinance operating on the site of the work or any of the provisions of this Code.
#### 3.2.10.4 Reason for Refusal and Remedy Thereof
Refusal of permit shall be accompanied with reason and the Building Official shall quote the relevant sections of this Code which the plans contravene. The applicant may correct or remove such reasons and reapply for permit with any fee that may be required. The Building Official shall scrutinise the resubmitted plan and if there be no further objections the plan shall be approved and permit issued.
## 3.3 Responsibilities and duties of the owner
### 3.3.1 General
The owner of a building or structure regulated by the provisions of this Code shall be responsible for carrying out the work in conformity with the provisions of this Code. Granting of permission for any work or approval of plans or inspection by the Building Official or any of his deputies shall not relieve the owner from such responsibility.
### 3.3.2 Right of Entry
The owner shall allow the Building Official to enter the site for the purpose of enforcing the Code as required by the provision of Sec 2.2.6 and for the purpose of inspection as provided in Sec 3.4 below.
### 3.3.3 Permit from Other Agencies
The owner shall obtain permit as may be applicable from other concerned agencies relating to building, zoning, grades, sewers, water mains, plumbing, signs, blasting, street occupancy, gas, electricity, highways and all other permits required in connection with the proposed work.
### 3.3.4 Notice of Completion
The owner shall notify the Building Official in the form prescribed in Appendix D of the completion of the work for which permit was granted. The Building Official may or may not cause an inspection of the completed work for verification of its conformity with the approved plan and design and certify accordingly on the form. The work shall not be accepted as complete without such certification from the Building Official.
### 3.3.5 Documents at Site
The owner shall preserve at the site a copy of all permits issued and all drawings approved by the Building Official. Results of tests carried out for determination of conformity of the work with the provisions of this Code shall also be preserved and made available for inspection during execution of the work.
## 3.4 Inspection
All works relating to a building or structure regulated by the provisions of this Code for which permits are required shall be subject to inspection by the Building Official. An engineer, architect, planner or a supervisor shall supervise the work and certify conformity of the work with the provisions of the Code. Such certificates shall be preserved at the site and produced before the Building Official during any inspection.
## 3.5 Unsafe buildings
### 3.5.1 General
All buildings considered to constitute danger to public safety or property shall be declared unsafe and shall be repaired or demolished as directed by the Building Official.
### 3.5.2 Examination
The Building Official shall examine or cause examination of every building reported to pose threat to safety or be damaged by wear and tear or accident and shall make a written record of such examinations.
### 3.5.3 Notification
If a building is found to be unsafe the Building Official shall notify the owner of the building and specify the defects thereof. The notice shall require the owner within a stated time either to complete the required repair or improvement or demolish and remove the building or portion thereof.
### 3.5.4 Disregard of Notice
In case the owner fails, neglects or refuses to carry out the repair or improvement of the unsafe building or portion thereof as specified in the notice, the Building Official shall cause the danger to be removed either by demolition or repair of the building or portion thereof or otherwise, the cost of which shall be borne by the owner.
### 3.5.5 Cases of Emergency
If the Building Official considers that an unsafe building or structure constitutes imminent danger to human life or health or public property, the Building Official shall at once or with a notice as may be possible promptly cause such building or structure or portion thereof to be rendered safe or removed. In such cases the decision of the Building Official shall be final and binding, and he or any of his assigned deputies may at once enter such structure or land on which it stands or the abutting land or structure, with such assistance from and at such cost to the owner as may be deemed necessary. The Building Official may also get the adjacent structures vacated and protect the public by an appropriate fence or such other means as may be necessary.
### 3.5.6 Cost Involvement
The cost incurred in carrying out the activities of the Building Official under Sec 3.5.4 and 3.5.5 above shall be realized from the owner of the building or structure or the premises concerned.
## 3.6 Demolition of buildings
If a building or structure is to be demolished, the owner shall notify all agencies providing utility services to the building. Such agencies shall remove all their appurtenances and equipment and dismantle all service connections to ensure a safe condition. The Building Official shall not grant any permit for demolition of a building until a release is obtained from the utility services stating that all service connections have been removed in the proper manner.
## 3.7 Validity of the provisions of this Code
### 3.7.1 Partial Invalidity
In case any provision of this Code is held to be illegal or void, this shall have no effect on the validity of any other provision of the Code nor on the same provision in different cases nor on the Code as a whole, and they shall remain effective.
### 3.7.2 Invalidity on Existing Buildings
If any provision of this Code is held to be illegal or void by the Authority as applied to an existing building or structure, validity of that provision or any other provision of the Code in its application to buildings hereafter erected shall not be affected.
## 3.8 Architectural and environmental control
### 3.8.1
Besides enforcing the provisions of this Code for normal buildings and structures, the Building Official shall, for special structures such as those listed in Sec 3.8.2 below, also examine the aesthetics and environmental issues vis-a-vis the existing structures and the characteristics of the area, and exercise architectural and environmental control in accordance with the provisions of this section.
### 3.8.2
Special structures for which architectural and environmental control shall be exercised by the Building Official shall include:
a) major public building complexes,
b) buildings in the vicinity of monuments and major sculptures,
c) buildings and structures near existing structures identified to be architecturally valuable (see Sec 1.16 of Part 3),
d) buildings and structures near historic buildings or in an area of historical or archaeological significance,
e) buildings near any structure that represents the special characteristics of an area,
f) any proposed building or structure that represents the special characteristics or forms part of a larger master plan of an area, and
g) any development that may have an effect on or mar the environment or characteristics of an area.
### 3.8.3
The Authority shall, for the purpose of exercising the architectural and environmental control and for identifying existing structures having architectural value, appoint a standing committee comprising noted experts from the fields of Architecture, Planning, Engineering, History, Art, Literature or any other discipline which may be deemed relevant. The committee shall examine the aesthetic quality of the proposed building, structure or development and the effect it may have on the characteristics and environment of the area in order to ensure aesthetic continuance of the new structure with the existing ones and aesthetic blending of the new structure with the surroundings. The committee may require additional drawings and information to those specified in Sec 3.2.3 for a detailed study of the proposed work. The committee, for the purpose of arriving at their decision, may at their discretion depending on the magnitude of the project and the impact it may have on public life, hear the architect of the proposed work who may wish to explain the various features of the project, note comments of other experts in the relevant disciplines, or in exceptional circumstances, institute a public hearing to assess public reaction to the project.
### 3.8.4
The committee may approve the proposed work, recommend changes in the scheme, or disapprove the scheme, for reasons of aesthetics and environmental control.
### 3.8.5
The Building Official shall not issue permit for undertaking the proposed work until obtaining a report from the standing committee stating that the intended work is acceptable in respect of its effect on the environment, landscape, architectural characteristics, historical feature or any other aesthetic quality of the locality, area or landscape concerned.
See also Sec 1.5 of Part 1 and Sec 1.16 of Part 3.
## Related appendices
See [Appendices A-D](/bnbc2006/part-2-administration-and-enforcement/appendices) for the forms referenced throughout this chapter: first application (Appendix A), certificate of supervision (Appendix B), sanction or refusal of permit (Appendix C), and completion certificate (Appendix D).
# Part II: Administration and Enforcement
Source: https://docs.sayed.app/bnbc2006/part-2-administration-and-enforcement/index
Purpose and scope, the code enforcement agency and Building Official, and permits and inspections.
Part 2 sets forth the administrative procedure for enforcement of the Code: the applicability of the Code, provision for designating a Building Official, powers and duties of such Building Official, obligations and liabilities of engineers, architects or planners, provisions against violation of the Code, and the procedure for obtaining building permits.
## Chapters
Purpose, scope, terminology, applicability, and alternative provisions.
The code enforcement agency, powers and duties of the Building Official, the Board of Appeals, and violation and penalties.
Permits, applications, responsibilities of the owner, inspection, unsafe buildings, and demolition.
## Appendices
Forms for application, certificate of supervision, sanction or refusal of permit, and completion certificate.
# Appendices
Source: https://docs.sayed.app/bnbc2006/part-3-general-building-requirements-control-and-regulation/appendices
## APPENDIX A: Guidelines for the Development of Minimum Standard Housing (Occupancy A4)
### A.1 GENERAL
#### A.1.1
Government bodies or public agencies may designate an area in the master plan for the development of mass housing projects for the low income people. It may not be convenient or practicable for the dwelling units in such projects to be in full compliance with all the requirements of this Code. All such dwelling units in planned layouts of an approved settlement shall be classified as Occupancy A4 : Minimum Standard Housing. The guidelines of this appendix cover the planning and the general building requirements of such minimum standard housing developments.
#### A.1.2
Only government bodies or public agencies should be responsible for planning the number and location of the settlements in a master plan and the layout of units within the settlement. The guidelines of this appendix regarding layout planning are applicable to government bodies or public agencies responsible for such planning.
#### A.1.3
The guidelines and requirements regarding design and construction of buildings for minimum standard housing in approved layouts are applicable to government bodies, public agencies, private developers or individual owners who undertake such constructions.
### A.2 TYPES OF DEVELOPMENT
The developments of minimum standard housing may be any one or a combination of the following types :
a) Single unit plots of row type housing,
b) Multi-storied flats of row type housing,
c) Block development as group or cluster housing, and
d) Site and service schemes.
The guidelines for planning and general building requirements shall be applicable to all types of development of minimum standard housing.
### A.3 PLANNING
#### A.3.1 Basic Master Plan Requirements
Each cluster of minimum standard housing should accommodate a maximum of 400 dwelling units with an average of 5 persons per dwelling. The following common spaces should be provided in the layout plan of a settlement :
Community open spaces like park, children's play area etc. : 1000 m² per 1000 population
Internal roads and walkways : 15 to 20 per cent of the site area
Primary school : 1 school covering 1000 m² per 1500 population
Shopping centre : 4 shops per 1000 population
Clinic/dispensary : 175 m² per 2000 population
Places of worship : 175 m² per 2000 population
Services : 175 m² per 2000 population
Community welfare centre : 400 m² per 1500 population
#### A.3.2 Density
The permissible density of dwelling units should be worked out in consideration of the minimum common space requirements given above and the size of the units. The density of minimum standard housing shall not be more than 175 units per hectare.
#### A.3.3 Size of Plot
**A.3.3.1** Minimum standard housing with one room, cooking space, bathing facility and water closet in the ground floor and prospect of future extension of one room and bath/WC on the first floor or ground floor shall normally require a minimum plot size of 30 m². In areas other than metropolitan cities, with population less than 0.5 million, the minimum size of plot for such houses should be 40 m².
**A.3.3.2** Developments having minimum standard houses with two rooms, kitchen, bathing facility and water closet in multi-storied flats, group housing or individual ownership houses shall require a minimum plot size of 40 m². In areas other than metropolitan cities, having a population less than 0.5 million, the minimum size of the plot for such houses should be 60 m². In dense inner city areas of metropolitan cities with population more than 1.5 million, the Government may decide to have a minimum plot size of 25 m² for such houses.
#### A.3.4 Plot Frontage
The minimum frontage of individual plots shall be 3.5 m. Plots for group housing developments in multi-storied blocks and plots for multi-storied flats will require a larger frontage.
#### A.3.5 Site and Service Schemes
**A.3.5.1** Minimum Provisions : Site and service schemes shall delineate individual plots and provide for the infrastructural needs for the development of a permanent housing. Interim constructions by the allottees should also be permitted. Skeletal structures with a roof on columns and/or developed plinths may be provided if funds are available.
**A.3.5.2** Sanitation : Sanitation and water supply must be provided in all site and service schemes. A sanitary service core or common water supply and sanitation facilities for planned groups of plots should normally suffice.
**A.3.5.3** The developing agency shall install the services before handing over the plots.
#### A.3.6 Internal Roads and Walkways
Pedestrian walkways when provided as means of access, shall be at least 3 m wide. Such walkways shall not be longer than 60 m, nor serve more than 10 plots on each side of the path. Buildings on plots abutting such walkways shall not be higher than two times the sum of the width of the walkway and the front open space.
Other internal roads shall be at least 6 m wide to allow emergency vehicles to enter. The paved portion of such roads, if used for pedestrian movement only, should be at least 2 m wide.
### A.4 GENERAL BUILDING REQUIREMENTS
#### A.4.1 Plinth Coverage
The plinth area coverage of any plot of minimum standard housing shall not exceed 75 per cent of the plot area. There shall be a set back of minimum 1.5 m on the rear side of a plot. There is no requirement for such set back on the sides and front of a plot.
#### A.4.2 Height Limitation
The height of any building in a minimum standard housing scheme shall not exceed 6 storeys or 20 m. Whenever feasible, the height should be limited to 5 storeys. For buildings on internal pedestrian walkways, the provisions of Sec A.3.6 regarding height shall be applicable.
#### A.4.3 Plinth Level
The minimum height of the plinth shall be 300 mm from the surrounding ground level.
#### A.4.4 Habitable Room
**A.4.4.1** One roomed dwelling units shall have a multi-purpose room which may include an alcove or space for cooking. The minimum area of the room shall be 12 m² with a minimum width of 2.5 m.
**A.4.4.2** For dwelling units with two habitable rooms the minimum size of any room shall be 6 m² with a minimum width of 2.1 m. The total area of the two rooms shall not be less than 15 m².
**A.4.4.3** One-roomed dwelling with plan for future extension into a two-roomed house in a staged construction scheme shall satisfy the requirement of A.4.4.2 regarding room sizes. The first room to be built in this type of development shall have a minimum area of 9 m² with a minimum width of 2.5 m. The total area of the two rooms after future extension shall be a minimum of 15 m².
**A.4.4.4** All habitable rooms shall have a minimum clear height of 2.75 m. For sloped roofs the average height shall not be less than 2.75 m with a minimum of 2 m at the lowest side.
#### A.4.5 Kitchen
**A.4.5.1** The size of the cooking alcove or cooking space provided in a multi-purpose room of a one-roomed house shall not be less than 2.25 m² with a minimum width of 1.2 m.
**A.4.5.2** Separate kitchen provided in a two-roomed house shall have a minimum area of 3.25 m² with a minimum width of 1.6 m.
**A.4.5.3** Minimum clear height of the kitchen or cooking space shall be 2.15 m.
#### A.4.6 Bathroom and Water Closet
**A.4.6.1** Independent water closets shall have a minimum width of 0.9 m and a minimum length of 1.15 m. The water closet shall be fitted with a door.
**A.4.6.2** Independent bathroom without water closet shall have a minimum width of 1 m and a minimum length of 1.4 m.
**A.4.6.3** The minimum size of a combined bathroom and water closet shall be 1.8 m² with a minimum width of 1 m. The bathroom shall be fitted with a door.
**A.4.6.4** The minimum clear height of bathrooms and water closets shall be 2.15 m.
#### A.4.7 Balcony and Corridor
The minimum width of individual balcony shall be 0.9 m. Corridors for use of more than one dwelling units shall have a minimum width of 1.2 m.
#### A.4.8 Stairs
**A.4.8.1** Minimum Width : The minimum widths of stairs serving not more than two dwelling units per floor shall be as follows :
2 - storeyed buildings 0.75 m
3 - storeyed buildings 0.80 m
4 - storeyed buildings 0.90 m
5 or 6-storeyed buildings 1.00 m
**A.4.8.2** Maximum Rise : The height of the riser shall not be more than 215 mm. The maximum number of risers per flight in a straight flight stair shall be 15.
**A.4.8.3** Minimum Tread Depth : The minimum depth of the tread shall be as follows :
2 or 3-storeyed buildings 215 mm
4, 5 or 6-storeyed buildings 250 mm
**A.4.8.4** Minimum Head Room : The minimum clear head room between flights of a staircase shall be 2.15 m. The clear head room may be reduced to 2.03 m for not more than three flights in any staircase.
**A.4.8.5** Landing : The depth of landing at any level shall be at least equal to the width of the stair.
#### A.4.9 Water Supply
One water tap or hand tubewell pump per dwelling unit should be provided, if feasible. Each unit of public water hydrants or community hand pumps, if provided in lieu of individual water supply, shall serve not more than 10 dwelling units and shall not be farther than 15 m from any dwelling unit served.
#### A.4.10 Lighting and Ventilation
Every room, bathroom and kitchen shall have windows in an external wall opening on a courtyard, a balcony not wider than 2.5 m, or the exterior. The aggregate area of openings in the exterior wall of a habitable room or kitchen shall not be less than 12% of the floor area and that for a nonhabitable room such as bath room, water closet or stair shall be at least 8% of the floor area.
***
## APPENDIX B: Suggestive Typical Termite Proof Constructions and Preconstructional Measures
### B.1 GENERAL
Constructions and preconstructional measures presented in the following sections may be adopted for design and construction of termite proof buildings.
### B.2 CONSTRUCTIONAL MEASURES
**B.2.1** Suggested typical anti-termite constructions for brick masonry works are shown in Fig B.1.
![Fig. B1 Anti-Termite Construction in Masonry Works]()
**B.2.2** Fig B.2 (a), (b) and (c) present termite shield, groove at entrance and arrangement at their junctions. Ends of termite shield shall overlap by at least 20 mm and soldered. A piece of 20x10 mm shall be cut off from the lower end portion of one of the pieces before soldering the two ends so that the thickness at the free edges remain constant.
![Fig. B2 (a) and (b) Termite Shield at Plinth Level and Anti-Termite Groove]()
![Fig. B2 (c) and Fig. B3]()
**B.2.3** Bottom of wooden columns supported directly on basement floors shall be protected with termite caps. Such caps shall be a metal sheet covering the whole section of the column and projecting 50 mm beyond the outer edge of the column.
### B.3 PRECONSTRUCTIONAL MEASURES
**B.3.1** For load bearing walls, treatment of soil shall be carried out at the bottom of the trenches and at the sides up to 300 mm above the bottom (Fig B.3 and B.4). In such cases, 5 litre of the chemical shall be sprayed per m² of the surface area. The backfill material in direct contact with the foundation shall be treated with 15 litre of chemical emulsion per m² of the surface area of the foundation. If water is used for compaction operation, it shall be done before applying the chemicals. Treatment shall follow the same layer wise sequence as that of the backfilling operation.
**B.3.2** For frame structures, if the concrete mix of the foundation is 1:2:4 or richer, treatment of soil at the bottom of the trench is not needed. A layer of treated soil at a depth of 500 mm from the ground level shall be prepared. Details of this treatment is shown in Fig B.5. The density of chemicals in such treatment shall be 15 litre/m³.
**B.3.3** The top surface of plinth in any building having a floor at the ground level shall be treated with a chemical emulsion at the rate of 5 litre/m².
![Fig. B4 and Fig. B5 Treatment for Foundations]()
# Chapter 1: General Building Requirements
Source: https://docs.sayed.app/bnbc2006/part-3-general-building-requirements-control-and-regulation/chapter-1-general-building-requirements
## 1.1 Scope
This part of the Code puts forward classification of buildings based on occupancy or nature of use and deals with the general and specific requirements of each of the occupancy groups. Fire resistance requirements are expressed in terms of type of construction which shall conform with the specified fire-resistive properties.
## 1.2 Terminology
This section provides an alphabetical list of the terms used in and applicable to this part of the Code. In case of any conflict or contradiction between a definition given in this section and that in Part 1, the meaning provided in this part shall govern for interpretation of the provisions of this part.
| Term | Definition |
| ------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **AREA PLANNING AUTHORITY** | A government or semi-government agency or a local body which has been legally designated to formulate land use or plans of the area under their jurisdiction. |
| **BALCONY** | A portion of the seating space in an assembly room the lowest of which is at least 1.2 m above the level of the main floor and shall include the area providing access to the seating area or serving only as a foyer. |
| **BALUSTER** | A short vertical member to support guard rails. |
| **BALUSTRADE** | A row of balusters meant for supporting handrails. |
| **BASEMENT** | A floor level below the first storey in a building, except that a floor level in a building having only one floor level shall be classified as a basement unless such floor level qualifies as a first storey as defined in Part 1. |
| **BUILDING LINE** | The line up to which the plinth of a building may lawfully extend. |
| **CITY DEVELOPMENT AUTHORITY** | A government or semi-government agency or a local body which has been legally designated to carry out and/or control development works of the area under its jurisdiction. |
| **FAR** | Abbreviation for Floor Area Ratio. Measured as the ratio of total covered area of all floors of a building to the area of the plot on which the building is erected or intended to be erected. |
| **FIRE SEPARATION DISTANCE** | The minimum distance to be maintained from considerations of fire safety between a building and any other building on the site, or from other site, or from the opposite side of a street or other public space. |
| **FRONTAGE** | Length of the side of a plot facing the street. There may be more than one frontages depending on the location of a plot with respect to the street. (See Fig 3.1.1 for definition of front, side and rear of a plot). |
| **GALLERY** | An intermediate floor or platform projecting from a wall of an auditorium or a hall providing extra floor area or additional seating accommodation. |
| **PLOT** | A piece or parcel of land on which a building is intended to be or has already been constructed. |
| **STRUCTURAL FRAME** | Columns, girders, beams, trusses and spandrels which have direct connections with the columns and all other members which are essential to the stability of the building or structure as a whole. |
| **TERRACE** | A level paved area or floor on or adjacent to a building usually open to the sky. |
| **VERANDAH** | A covered area with at least one side open to the outside. |
## 1.3 Occupancy classification of buildings
Every building or portion thereof shall be classified according to its use or character of occupancy. A brief description of such occupancy groups is presented in Table 3.1.1. Details of each Occupancy and its sub-divisions are set forth in Sec 2.1. Occupancy A4 (Minimum Standard Housing) is described in Appendix A. Types of construction based on fire resistance are specified in Table 3.1.2. Details of such types of construction are set forth in Sec 3.1.
**Table 3.1.1 — Summary of Occupancy Classification** (Details in Sec 2.1. Details of Occupancy A4 in Appendix A)
| Occupancy type | Sub-division | Nature of use or occupancy |
| -------------------------- | ------------ | -------------------------------------------------------------- |
| A: Residential | A1 | Detached single family dwelling |
| | A2 | Flats or apartments |
| | A3 | Mess, boarding houses, dormitories and hostels |
| | A4 | Minimum standard housing |
| | A5 | Hotels and lodging houses |
| B: Educational | B1 | Educational facilities |
| | B2 | Preschool facilities |
| C: Institutional | C1 | Institutions for care of children |
| | C2 | Custodial institutions for physically capable |
| | C3 | Custodial institutions for physically incapable or handicapped |
| | C4 | Penal and mental institutions |
| D: Health Care | D1 | Normal medical facilities |
| | D2 | Emergency medical facilities |
| E: Assembly | E1 | Large assembly with fixed seats |
| | E2 | Small assembly with fixed seats |
| | E3 | Large assembly without fixed seats |
| | E4 | Small assembly without fixed seats |
| | E5 | Sports facilities |
| F: Business and Mercantile | F1 | Offices |
| | F2 | Small shops and markets |
| | F3 | Large shops and markets |
| | F4 | Garages and petrol stations |
| | F5 | Essential services |
| G: Industrial | G1 | Low hazard industries |
| | G2 | Moderate hazard industries |
| H: Storage | H1 | Low fire risk storage |
| | H2 | Moderate fire risk storage |
| J: Hazardous | J1 | Explosion hazard building |
| | J2 | Chemical, biological or radiation hazard building |
| K: Miscellaneous | K1 | Private garages and special structures |
| | K2 | Fences, tanks and towers |
**Table 3.1.2 — Classification of Buildings Based on Types of Construction** (Details in Sec 3.1)
| Type | Description |
| ---- | ---------------------------------- |
| 1 | Highest degree of fire resistance |
| 2 | Moderate degree of fire resistance |
| 3 | Lowest degree of fire resistance |
## 1.4 Land use classification and permitted uses
Every city, township, municipality or other development shall be divided into zones according to the intended land use pattern by the development and planning authorities and approved by the Government. This land use classification may divide an area into zones such as residential, commercial, industrial, storage, green park etc. or any combination of these. The land use zones shall be shown on the approved master plan of the area and the permitted occupancy classes for each zone clearly stated in the planning regulations. The Occupancy classes permitted in any zone shall be one or more of the Types of Occupancy defined in Sec 2.1.
## 1.5 Requirements of plots
### 1.5.1 General Requirements
#### 1.5.1.1
No building shall be constructed on any site which is water logged, or on any part of which is deposited refuse, excreta or other objectionable material, until such site has been effectively drained and cleared to the satisfaction of the Authority.
#### 1.5.1.2
Provision shall be kept for any space within the plot left vacant after the erection of the building to be effectively drained by means of surface or underground drainage system.
#### 1.5.1.3
Basic minimum sanitary waste and excreta disposal facility shall be created on the premises, unless the plot is served by a disposal system provided by any utility service authority or agency.
#### 1.5.1.4
Written approval of the Authority or the appropriate drainage and sanitation authority shall be obtained for connecting any soil or surface water drain to the sewer line.
### 1.5.2 Clearance from Overhead Electric Lines
No building or any part thereof shall be erected within, nor any auxiliary part of the building be allowed to come closer than, the distances shown in Table 3.1.3 from any overhead electric line.
**Table 3.1.3 — Minimum Distances from Overhead Electric Lines**
| Line Voltage | Vertically (m) | Horizontally (m) |
| --------------------------------------------- | ------------------------------------------------------ | ------------------------------------------------------- |
| Low to medium voltage lines and service lines | 2.5 | 1.25 |
| High voltage lines up to 33 kV | 3.5 | 1.75 |
| High voltage lines beyond 33 kV | 3.5 plus 0.3 for each additional 33 kV or part thereof | 1.75 plus 0.3 for each additional 33 kV or part thereof |
### 1.5.3 Plinth and Formation Levels
The formation level of the plot shall not be lower than the adjacent road level. In areas not susceptible to flood, the formation level shall not be higher than 450 mm from the surface level of the centre line of the adjacent front road. For flood prone and uneven or undulated areas the permitted height of the formation level shall be decided by the Authority considering the general characteristics of the terrain and future development plans. The plinth or ground floor level of the building shall be at least 450 mm above the surface level of the centre line of the adjacent front road.
### 1.5.4 Boundary Wall
Solid boundary walls surrounding a plot not higher than 1.5 m and open boundary walls made of grill, jali (screen), balustrade etc. with a maximum height of 2.75 m shall not require the permission of the Authority. For boundary walls made of a combination of solid wall and open grill or jali, the solid wall portion shall not be higher than 1.5 m. The Authority may, on specific application, permit the use of higher boundary walls.
### 1.5.5 Plot Sizes
#### 1.5.5.1 Residential Plots
a) The minimum size of the plot shall be 65 m².
b) Corresponding to each type of residential development the sizes of the plots and the corresponding minimum widths of road frontage of the plots shall be as specified in Table 3.1.4, provided that:
i) plots accessible by link roads shall be considered to have a frontage equal to its width, and
ii) plots of irregular shape abutting the road shall be considered to have a frontage equal to their average width parallel to the road.
**Table 3.1.4 — Plot Sizes and Corresponding Minimum Frontages for Various Types of Residential Development**
| Type of Residential Development | Plot Size (m²) | Minimum Frontage (m) |
| ------------------------------- | ------------------ | -------------------- |
| Approved row type houses | 65 (Minimum size) | 4.5 |
| | Over 65 to 135 | 7 |
| Detached houses | 65 (Minimum size) | 5.5 |
| | Over 65 to 135 | 7 |
| | Over 135 to 200 | 8 |
| | Over 200 to 265 | 10 |
| | Over 265 | Above 10 |
| Semi-detached houses | 135 (Minimum size) | 7 |
| | Over 135 to 200 | 8 |
| | Over 200 to 265 | 10 |
| | Over 265 | Above 10 |
c) The limitations of plot sizes and frontages imposed in (a) and (b) above may be waived for approved low income housing including site and service schemes. Guidelines governing the planning and design of such housing are given in Appendix A.
d) The minimum size of the plot for a group housing development scheme and other special requirements for group housing developments shall be as specified or approved by the respective city development authority.
e) Common private road or family road serving not more than four plots shall be at least 2.5 m wide. Open space requirements and height and area limitations of buildings on such plots shall be decided in view of the nearest public road.
f) Common private road or family road serving more than four plots shall be at least 3.5 m wide. Notwithstanding any other requirement for front open space, a residential building may be permitted to be constructed at a minimum distance of 1.5 m from the front property line of such plots.
#### 1.5.5.2 Plots for Educational Buildings
The minimum size of plot for educational buildings shall be based on occupant capacity and shall be at the rate of 4 m² per pupil or occupant. In no case shall the size of the plot be less than 200 m².
#### 1.5.5.3 Plots for Assembly Halls, Theatres, Cinema
The minimum size of plot for assembly halls, theatres, cinema halls and other similar buildings where people gather for entertainment or other public functions shall be based on the seating capacity of the building and shall be at the rate of 3 m² per seat.
#### 1.5.5.4 Plots for Community Centres
The size of plot for rural or urban community centres shall be not less than 1300 m² and commensurate with the size of the community.
#### 1.5.5.5 Business and Mercantile Plots
The minimum size of a business and mercantile plot shall be 200 m² and its road frontage width shall not be less than 10 m.
#### 1.5.5.6 Industrial Plots
The minimum size of an industrial plot shall be 300 m² and its road frontage width shall not be less than 15 m.
#### 1.5.5.7 Petrol Filling Stations
The minimum size of the plot for a petrol filling station without service bay or repair workshop shall be 500 m² and its road frontage width shall not be less than 30 m. The minimum size of the plot for a petrol filling station with service bay but without repair workshop shall be 1100 m² and its road frontage width shall not be less than 30 m.
#### 1.5.5.8 Plots for Other Uses
The minimum sizes of plots for buildings for uses other than those mentioned in 1.5.5.1 to 1.5.5.7 shall be as determined by the Authority for specific areas.
## 1.6 Means of access
### 1.6.1
All buildings and plots shall be approachable by a public or private road or street or an approved means of access.
### 1.6.2 Residential Plots
Public roads or means of access on which a residential plot abuts shall satisfy the minimum width requirements depending on the type of development and plot size specified in Table 3.1.5. Minimum widths of common private road or family road shall be as specified in 1.5.5.1 (e) and (f).
**Table 3.1.5 — Minimum Widths of Public Means of Access to Residential Plots**
| Type of Development | Plot Size (m²) | Minimum Width of Access Road — Existing Development (m) | Minimum Width of Access Road — New Development (m) |
| ------------------- | ------------------ | ------------------------------------------------------- | -------------------------------------------------- |
| Approved row Type | 65 (minimum size) | 3.0 | 4.5 |
| | Over 65 to 135 | 3.5 | 4.5 |
| Detached | 65 (minimum size) | 2.5 | 4.75 |
| | Over 65 to 135 | 2.5 | 6.0 |
| | Over 135 to 200 | 2.5 | 7.5 |
| | Over 200 to 265 | 2.5 | 9.0 |
| | Over 265 | Over 3.0 | Over 9.0 |
| Semi-detached | 135 (minimum size) | 2.5 | 6.0 |
| | Over 135 to 200 | 2.5 | 7.5 |
| | Over 200 to 265 | 2.5 | 9.0 |
| | Over 265 | Over 3.0 | Over 9.0 |
Note: Existing Development — Any approved residential development already in existence on the date of promulgation of this Code, with roads and streets for which the area planning authority does not have any scheme for future widening. New Development — Any new residential development implemented subsequent to the promulgation of this Code.
### 1.6.3 Assembly buildings
For Assembly buildings such as cinema halls, theatres, halls for wedding receptions etc. where large crowds are likely to assemble, the width of the approach road shall not be less than 15 m.
### 1.6.4 Other Buildings
The width of the approach road for all plots other than residential and assembly shall be not less than 9 m.
### 1.6.5 Internal Roads
#### 1.6.5.1
The width of internal roads and drive ways in a plot shall be decided by the number of buildings served. For internal roads on residential plots the provisions of Sec 1.5.5.1 (e) and (f) shall apply. For plots other than residential the width of internal roads and driveways shall be not less than 7 m. The permissible maximum length of internal roads for non-residential plots shall depend on their widths and shall be as specified in Table 3.1.6.
**Table 3.1.6 — Maximum Permissible Length of Internal Roads in Non-Residential Plots**
| Width (m) | Maximum Permissible Length (m) |
| ---------- | ------------------------------ |
| 7 | 80 |
| 8 | 150 |
| 9 | 300 |
| 10 or over | Unlimited |
#### 1.6.5.2
The internal roads in all types of plots shall be set back not less than 250 mm from the boundary wall/property line and the building.
### 1.6.6 Pedestrian Walkways
#### 1.6.6.1
The exterior pedestrian walkway that links buildings and the approach road shall not contribute to the building area.
#### 1.6.6.2
The walkway shall not be used for any purpose other than pedestrian movement.
#### 1.6.6.3
The minimum width of the walkway shall be 1.0 m provided the walkway is not enclosed by adjacent walls on both sides, otherwise the minimum width shall be 1.25 m.
#### 1.6.6.4
Pedestrian walkways for access to different dwelling units in one or two-storeyed low income row or cluster housing schemes or site and service facilities shall be at least 3 m wide, subject to the condition that the height of the building shall not exceed two times the sum of the width of the walkway abutting and the front open space. The pedestrian walkway of 3 m width shall serve a maximum of 10 plots on each side of the walkway. The length of such walkway shall be limited to 60 m.
## 1.7 Open spaces within a plot
### 1.7.1
For the purpose of applying the provisions of open space requirements, the side, rear and front of a plot shall be defined as shown in Fig 3.1.1 depending on the layout of roads around the plot.
![Definition of Front, Side and Rear of a Plot]()
### 1.7.2
At least one side of all habitable rooms shall be exposed to an exterior or an interior open space or to a balcony or verandah.
### 1.7.3
The total open area in a plot on which a building of educational, institutional, health care or assembly occupancy is constructed shall not be less than 50 per cent of the plot area.
### 1.7.4
The total open area in a plot on which a building of residential, industrial, storage, hazardous or miscellaneous occupancy is constructed shall not be less than 33 per cent of the plot area.
### 1.7.5
For the purpose of Sec 1.7.3 and 1.7.4, the total open area shall include all exterior open spaces and interior courtyards, but exclude the area of any lighting and ventilation shaft.
### 1.7.6
For approved low income row type or cluster housing or site and service schemes, the requirement of 1.7.3 may be relaxed by the Authority taking into consideration the density of occupancy, width of the approach road, fire safety and general lighting and ventilation (see Appendix A).
### 1.7.7
The total open area requirement for plots on which buildings of business and mercantile occupancy are constructed shall be as decided by the Authority for specific city, municipality, township or area taking into consideration fire safety, height of the building, parking facilities, occupancy load, abutting road widths and general lighting and ventilation.
### 1.7.8 Separation of Buildings in the Same Plot
For more than one building in the same plot, a minimum separation of 2 m between the buildings shall be maintained if the heights of both the adjacent buildings are not more than 8 m nor two storeys. If the height of either of the adjacent buildings in the same plot is more than 8 m or two storeys, mandatory open spaces between the buildings as specified in Fig 3.1.2 (a) to (c) and in the following shall be maintained:
a) For grid iron layouts such as those shown in Fig 3.1.2 (a), the end to end open space between the buildings shall not be less than 2 m. The open space between the longer sides of the buildings shall not be less than 0.5 times the height of the shielding building on the south or the east.
b) For staggered layouts such as those shown in Fig 3.1.2 (b), the open space between the longer sides of the buildings shall not be less than 0.4 times the height of the shielding building on the south or the east, provided that at least 0.33 times the length of the shielded building is left unshielded by the shielding building.
c) For front to end layouts such as those shown in Fig 3.1.2 (c), the open space between the buildings shall not be less than 3 m, provided that the width of the shielding building on the south or the east is not more than 0.33 times the length of the shielded building. When the width of the shielding building is more than 0.33 times but less than 0.67 times the length of the shielded building, the open space between the buildings shall be at least 0.4 times the height of the shielding building; otherwise the open space between the buildings shall be at least 0.5 times the height of the shielding building. For the purpose of this requirement the width of the shielding building shall be taken as that portion of its width which actually shields the other building, or the aggregate of such widths of all shielding buildings, as the case may be.
![Open Space Requirements Between Adjacent Buildings in the Same Plot in Different Layouts]()
### 1.7.9 Road Front Open Space for All Buildings
#### 1.7.9.1
All buildings facing a street and having a height not more than 17 m or five storeys shall be constructed at a distance of at least 4.5 m from the centre of the street or at least 1.5 m from the road front property line whichever is greater.
#### 1.7.9.2
All buildings facing a street and having a height more than 17 m or 5 storeys shall be constructed at a distance of at least 4.5 m from the centre of the street or at least 2 m from the road front property line whichever is greater.
#### 1.7.9.3
In case a building abuts two or more roads, the road front open space requirement specified in Sec 1.7.9.1 and 1.7.9.2 shall be applicable to all the road fronts of the plot (see Fig 3.1.1).
### 1.7.10 Side and Rear Open Spaces
#### 1.7.10.1
The minimum side and rear open space requirements of a plot for buildings of various occupancy classes shall be as specified in Table 3.1.7.
#### 1.7.10.2
For approved row type residential, commercial or other buildings as may be permitted by the respective city or area development authority and for approved low income row type, cluster or site and service schemes, the requirement of side open space may be waived.
#### 1.7.10.3
For semidetached buildings approved by the city or area development authority, which are permitted to be constructed with one side on the property line, the minimum requirements of open space, specified in Sec 1.7.9, 1.7.10.1 and 1.7.10.2, for the side opposite to that property line shall be increased by 0.5 m. The requirement of open space for the remaining sides shall remain unchanged.
**Table 3.1.7 — Minimum Rear and Side Open Space Requirements of a Plot**
| Occupancy | Plot Size (m²) | Minimum Rear Open Space (m) | Minimum Side Open Space (m) |
| ------------------------------------------------------------------------------------ | --------------- | --------------------------- | --------------------------- |
| Residential (Not higher than 10 storeys or 33 m) | Not over 135 | 1.25 | Nil |
| | Over 135 to 200 | 1.5 | 1.25 |
| | Over 200 to 265 | 1.75 | 1.25 |
| | Over 265 to 330 | 2.5 | 1.25 |
| | Over 330 to 660 | 3.0 | 1.25 |
| | Over 660 | 4.0 | 1.25 |
| Residential (Higher than 10 storeys or 33 m) | Any | 4.0 | 3.0 |
| Business and Mercantile (Not higher than 10 storeys or 33 m) | Any | 1.5 | 1.5 |
| Business and Mercantile (Higher than 10 storeys or 33 m) | Any | 2.0 | 2.0 |
| Educational, Institutional, Health Care, Assembly, Industrial, Storage and Hazardous | Any | 3.0 | 3.0 |
Note: For residential buildings not higher than 10 storeys or 33 m, if the rear property line of the plot is curved or not a continuous straight line or not parallel with the building, the minimum rear open space requirement shall apply to the average distance of the rear property line from the building, but at no point shall the distance be less than 1.25 m.
### 1.7.11 Interior Courtyard
#### 1.7.11.1
If any room depends entirely on an interior open space for its natural light and ventilation, such interior open space shall be in the form of an interior courtyard open to the sky over its entire cross-section. The interior courtyard shall have the minimum dimensions depending on the height of the building as specified in Table 3.1.8. The shorter side dimension of such interior courtyard shall not be less than one-third of the longer side dimension.
For buildings over 20 storeys high, the size of the interior courtyard shall not be less than the square of one-third the height of the tallest wall abutting the courtyard.
#### 1.7.11.2
The courtyard shall not be interrupted by any form of construction at the courtyard level, except landscaping, sculpture etc.
#### 1.7.11.3
If the courtyard is to serve as a component of the means of escape, it shall be accessible from all exit points at ground level.
### 1.7.12 Permitted Construction in the Mandatory Open Space
#### 1.7.12.1
No construction except landscaping, sculpture etc. shall be permitted in the interior courtyard.
#### 1.7.12.2
A maximum of one-third of the mandatory exterior open space in a plot required by the provisions of Sec 1.7.9 and 1.7.10 may be used for construction of garage, servants' quarter and other services auxiliary to and required for the main occupancy of the building, provided that the building is not higher than 10 storeys or 32 m, and provided further that conditions (a) to (g) below are satisfied:
a) No such construction permitted in the mandatory open space shall be higher than 2.75 m from the formation level of the plot, except for the tops of inverted beams or intermittent parapets, which may rise up to 3.25 m.
b) No window, door or ventilator shall be placed on any wall adjacent to the abutting property or street.
c) Entrance to the garage shall not be directly from the road. A minimum distance of 1.5 m shall be kept between the entrance to the garage and the property line adjoining the road.
d) Drainage from the roof or any other part of such construction shall not be allowed to discharge into the adjacent property. Drainage from any part shall not discharge directly into the street through spouts.
e) No structure or room shall be constructed over the garage or any other permitted service structure within the limits of the mandatory open space.
f) The roof of any construction permitted in the mandatory open space shall not be used as a balcony or a terrace or in any such manner that would interfere with the privacy of the occupants of the adjacent property.
g) No toilet shall be constructed adjoining the abutting property or street.
**Table 3.1.8 — Minimum Area of Interior Courtyard**
| No. of Storeys | Maximum Height (m) | Minimum Net Area of the Interior Courtyard (m²) |
| -------------- | ------------------ | ----------------------------------------------- |
| Up to 3 | 11 | 9 |
| 4 | 14 | 16 |
| 5 | 17 | 25 |
| 6 | 20 | 36 |
| 7 | 23 | 49 |
| 8 | 26 | 64 |
| 9 | 29 | 81 |
| 10 | 32 | 100 |
| 11 | 36 | 121 |
| 12-13 | 42 | 144 |
| 14-15 | 48 | 196 |
| 16-17 | 54 | 256 |
| 18-20 | 63 | 361 |
#### 1.7.12.3
Roof or cornice of the building may be extended into the mandatory open space for a maximum distance of 0.5 m. The construction of the roof shall be such that rain or other water from the roof is not drained into the neighbouring property or street.
#### 1.7.12.4
Sunshades over exterior doors or windows of the building may extend into the mandatory open space for a maximum distance of 0.75 m, provided that such sunshades are at least 2.5 m above the formation level of the ground.
#### 1.7.12.5
Cantilever canopy at a clear height of at least 2.5 m above the formation level may project into the mandatory open space provided that a clearance of at least 1.5 m is maintained between the edge of the canopy and the property line. The top of such canopy shall not be used as a balcony and shall not be accessible from the building.
#### 1.7.12.6
Balconies at levels higher than 6 m may project into the mandatory open space by not more than 0.9 m provided that a clearance of at least 1.5 m is maintained between the edge of the balcony and the property line.
#### 1.7.12.7
Underground constructions such as water reservoirs, septic tanks, inspection pits, sewer lines etc. shall be permitted in the mandatory open space provided that no part of such construction projects more than 150 mm above the formation level.
## 1.8 General height and area limitations
### 1.8.1
Not withstanding the requirements of open spaces and the height limitations specified in Sec 1.7, the maximum permissible height and area of a building shall not be more than the provisions of Sec 1.8.2 and 1.8.3.
### 1.8.2 Height Limitations Based on Road Width
#### 1.8.2.1
The maximum height of any building of Type 1 construction shall not exceed the nominal value of two times the sum of the width of the front road and the front open space (distance between the front property line and the building). For the purpose of fulfilling this requirement, the height limitations specified in Table 3.1.9 shall apply.
#### 1.8.2.2
For plots having front road width not less than 23 m in an approved residential or business and mercantile area, there shall be no restriction on height for residential and business & mercantile buildings of Type 1 construction, provided the minimum open space requirements specified in Table 3.1.10 are satisfied.
#### 1.8.2.3
For Type 2 construction, the maximum permissible height of the building shall be 4 storeys or 14 m for values of two times the sum of the width of the front road and the front open space not less than 13.6 m.
#### 1.8.2.4
For Type 3 construction, the maximum permissible height of the building shall be 3 storeys or 11 m for values of two times the sum of the width of the front road and the front open space not less than 13.6 m.
#### 1.8.2.5
For applying the provisions of Sec 1.8.2.1 through 1.8.2.4, the width of the front road for the layouts shown in Fig 3.1.1 (b), (c), (d), (e) and (f) where the plot abuts more than one road, shall be taken as the average of the widths of the abutting roads.
**Table 3.1.9 — Height Limitations Based on Road Width and Front Open Space**
| 2 times (Front Road Width Plus Front Open Space) | Type 1 — No. of storeys | Type 1 — Height (m) | Type 2 — No. of storeys | Type 2 — Height (m) | Type 3 — No. of storeys | Type 3 — Height (m) |
| ----------------------------------------------------- | ----------------------- | ------------------- | ----------------------- | ------------------- | ----------------------- | ------------------- |
| Below 10.6 m | 3 | 11 | 2 | 8 | 2 | 8 |
| 10.6 m to below 13.6 m | 4 | 14 | 3 | 11 | 2 | 8 |
| 13.6 m to below 16.6 m | 5 | 17 | 4 | 14 | 3 | 11 |
| 16.6 m to below 19.6 m | 6 | 20 | 4 | 14 | 3 | 11 |
| 19.6 m to below 22.6 m | 7 | 23 | 4 | 14 | 3 | 11 |
| 22.6 m to below 25.6 m | 8 | 26 | 4 | 14 | 3 | 11 |
| 25.6 m to below 28.6 m | 9 | 29 | 4 | 14 | 3 | 11 |
| 28.6 m to below 31.6 m | 10 | 32 | 4 | 14 | 3 | 11 |
| 31.6 m to below 34.6 m | 11 | 36 | 4 | 14 | 3 | 11 |
| 34.6 m to below 37.6 m | 12 | 39 | 4 | 14 | 3 | 11 |
| 37.6 m to below 40.6 m | 13 | 42 | 4 | 14 | 3 | 11 |
| 40.6 m to below 43.6 m | 14 | 45 | 4 | 14 | 3 | 11 |
| 43.6 m to below 46.6 m and so on in increments of 3 m | 15 | 48 | 4 | 14 | 3 | 11 |
Note: For plots with front road width (Sec 1.8.2.5) not less than 23 m, residential and business & mercantile buildings of Type 1 construction shall have no height restriction subject to additional open space requirements (Sec 1.8.2.2). The maximum permissible height for Type 2 construction is 4 storeys or 14 m (Sec 1.8.2.3). The maximum permissible height for Type 3 construction is 3 storeys or 11 m (Sec 1.8.2.4).
#### 1.8.2.6
For buildings more than six storeys or 20 m high, the following arrangements shall be provided:
a) Lifts of adequate size, capacity and number (See Chap 5, Part 8);
b) Adequate fire protection and fire fighting arrangements (See Part 4);
c) Separate emergency fire escape stair.
**Table 3.1.10 — Minimum Open Space Requirements for Buildings of Unlimited Height and Area** (Sec 1.8.2.2 and 1.8.3.5)
| Occupancy | Minimum Open Space — Front (m) | Minimum Open Space — Rear (m) | Minimum Open Space — Side (m) |
| -------------------------------- | ------------------------------ | ----------------------------- | ----------------------------- |
| Residential | 4.0 | 6.0 | 4.0 |
| Business and Mercantile or other | 6.0 | 6.0 | 6.0 |
#### 1.8.2.7
For buildings in the vicinity of airports or aerodromes, the height shall be limited by the requirements of the civil aviation authority, city or area development authority or other concerned agencies of the Government.
### 1.8.3 Area Limitations Based on FAR
#### 1.8.3.1
The limiting total building area for different classes of Occupancy and Types of construction shall be based on the maximum permissible floor area ratio (FAR). For the purpose of this section, FAR shall be calculated as the total floor area of the building in all the storeys divided by the area of the plot.
#### 1.8.3.2
The maximum permissible values of FAR for different classes of Occupancy and Types of construction shall be as specified in Table 3.1.11.
#### 1.8.3.3
The FAR values specified in Table 3.1.11 are based on the following considerations:
a) that the approach roads to the plots do not suffer from traffic congestion problems of a serious nature;
b) that the use of the plot as well as that of the others in the area conform with the land use classification indicated in the master plan;
c) that adequate off street car parking facilities are created in conformity with the provisions of this Code;
d) that adequate utility services such as gas, electricity, water supply, drainage etc. are provided in accordance with the requirements of this Code;
e) that fire fighting facilities are available locally so that the fire brigade is able to arrive within half an hour of a distress call; and
f) that adequate fire protection measures are provided in the building in accordance with the requirements of this Code for the Occupancy class and Type of construction of the building.
**Table 3.1.11 — Maximum Permissible Floor Area Ratios (FAR)**
| Occupancy | Type 1 | Type 2 | Type 3 |
| -------------------------- | ------ | ------ | ------ |
| A1 Residential | 3.0 | 2.0 | 1.5 |
| A2 | UL | 2.0 | 1.5 |
| A3 | UL | 2.0 | 1.5 |
| A4 | 4.5 | 3.0 | 1.5 |
| A5 | UL | 2.0 | 1.5 |
| B1 Educational | 2.5 | 1.5 | 0.5 |
| B2 | 2.0 | 1.5 | 0.5 |
| C1 Institutional | 3.0 | 1.5 | 0.5 |
| C2 | 3.0 | 1.5 | 0.5 |
| C3 | 3.0 | 1.5 | 0.5 |
| C4 | UL | NP | NP |
| D1 Health Care | 6.0 | 1.5 | 1.0 |
| D2 | 4.0 | NP | NP |
| E1 Assembly | 3.5 | 1.0 | 0.5 |
| E2 | 3.5 | 1.0 | 0.5 |
| E3 | 3.5 | 1.0 | 0.5 |
| E4 | 3.5 | 1.0 | 0.5 |
| E5 | 3.5 | 0.5 | 0.25 |
| F1 Business and mercantile | UL | 2.0 | 1.5 |
| F2 | 4.0 | 1.5 | 1.0 |
| F3 | UL | 2.0 | 1.5 |
| F4 | 6.0 | 1.5 | 1.0 |
| F5 | 3.0 | NP | NP |
| G1 Industrial | 7.5 | 1.5 | 1.0 |
| G2 | 5.0 | 1.5 | 1.0 |
| H1 Storage | 6.0 | 1.5 | 1.0 |
| H2 | 4.0 | 1.0 | 0.5 |
| J1 Hazardous | 3.0 | NP | NP |
| J2 | 2.0 | NP | NP |
Note: UL = Unlimited, NP = Not permitted. For occupancy classification of buildings, see Sec 2.1. For classification based on type of construction, see Sec 3.1.
#### 1.8.3.4
The values of FAR specified in Table 3.1.11 shall be applicable in general, unless the city or area development authority specifies different values of FAR for a particular zone or area with the approval of the Authority. In specifying any deviation in FAR from Table 3.1.11, the city or area development authority shall take into consideration the following:
a) Occupancy group,
b) Type of construction,
c) Width of approach roads,
d) Traffic density in the approach roads,
e) Population density of the area,
f) Parking facilities,
g) Utility services,
h) Local fire fighting facilities.
#### 1.8.3.5
For Occupancy for which unlimited area is permitted by Table 3.1.11, the minimum open space requirements specified in Table 3.1.10 shall be applicable.
#### 1.8.3.6
For the purpose of calculating FAR, the area of any floor including basement, of which at least two-third is used exclusively for car parking and the remaining one-third is used for purposes such as mechanical plant room, electrical substation, security cabin, reception booth, water tank, pump house, stairs and lifts, which are accessory to the main occupancy, shall be excluded from the total floor area of the building.
### 1.8.4
The height limitations imposed in Sec 1.8.2 (Table 3.1.9) can be exceeded for stepped tower structures if the area limitations imposed by the FAR requirements of Sec 1.8.3 are not exceeded, provided the following conditions are satisfied:
a) the building is of Type 1 construction;
b) the front road width is at least 9 m;
c) local conditions or regulations do not restrict the height (Sec 1.8.2.7);
d) the minimum ground level open spaces of Table 3.1.10 are maintained as for buildings of unlimited height;
e) every part of the building is contained within the envelope shown in Fig 3.1.3, which is a volume bounded by vertical sides at required distances from the property line up to the height limited by the requirements of Sec 1.8.2, topped by a pyramid with sides inclined at 2 vertical to 1 horizontal.
![Limiting Envelope for Stepped Tower Structures]()
## 1.9 Off street parking spaces
### 1.9.1
Every building shall be provided with adequate arrangements for entrance, exit, loading, unloading and parking of vehicles. The parking spaces can be either covered or open.
### 1.9.2
Ramps, if provided, shall have a grade not steeper than 1 vertical to 8 horizontal.
### 1.9.3
The parking space shall be provided either within the building or adjacent to it within the plot.
### 1.9.4
A 23 m² space shall be allotted for parking of each car. The number of parking spaces required shall be based on the total floor area of the building and shall depend on its occupancy. Parking spaces shall be provided for various occupancies at the following minimum rates:
| Occupancy | Parking Requirement |
| ------------------------------- | -------------------------------------- |
| A. Residential (A1 & A2) | 1 car for every 300 m² |
| " (A5) | 1 car for every 200 m² |
| B. Educational | 1 car for every 200 m² |
| C. Institutional | 1 car for every 300 m² |
| D. Health Care | 1 car for every 300 m² |
| E. Assembly | 1 car for every 20 occupants or 100 m² |
| F. Business and Mercantile (F1) | 1 car for every 200 m² |
| " (F5) | 1 car for every 100 m² |
| G. Industrial | 1 car for every 300 m² |
| H. Storage | 1 car for every 25 occupants |
| J. Hazardous | 1 car for every 25 occupants |
### 1.9.5
For storage and industrial buildings, required space for loading and unloading of at least one truck/lorry shall be provided.
### 1.9.6
When administrative or sales offices are located in the industrial premises, parking space for one car for every 300 m² of the office area shall be provided in the premises.
### 1.9.7
For residential buildings with front road width not less than 9 m, the parking space requirements may be reduced or waived provided the road is not too busy to preclude on street parking. The city or area development authority shall earmark all such streets where on street parking for adjacent residential property is not permitted.
### 1.9.8
In planned commercial developments, where separate car parking facilities are available, the parking space requirements of neighbouring buildings may be reduced or waived. The city or area development authority shall have all such commercial areas and commercial plots identified in the master plan.
### 1.9.9
In areas other than metropolitan cities, the city or area development authority may waive or alter the minimum parking requirements with the approval of the Authority.
## 1.10 Street encroachment
No part of any building shall project beyond the property line or building line established by the provisions of this Code into the street, except the following:
a) Below Grade: The footing of the boundary wall adjacent to the street may encroach the street land not more than 0.3 m at least 1.5 m below grade.
b) Above Grade: Marquee, canopy or other temporary projection of cantilever type from buildings of business and mercantile occupancy may project on the footpath of a road, provided that no part of such projection is below a height of 3 m from the footpath level and that the outer edge of the canopy is at a minimum clear horizontal distance of 0.25 m from the road side edge of the footpath. The canopy shall be so constructed as to be readily removable without endangering the building structure. No canopy shall project into a street without a footpath.
## 1.11 Community open space and amenities
### 1.11.1 Community Space for a Single Tall Building
For all residential or residential-cum-business buildings having ten or more storeys, community space at the rate of 5% of the total floor area shall be provided either within the building or outside within the premises solely for use of the occupants of the building. Roofs of such buildings shall not be considered as community open spaces. For residential or residential-cum-business plots measuring more than 0.1 hectare, 10% of the area of land shall be left vacant to be used as children's playground. This playground shall be contiguous and shall have a length not exceeding 2.5 times its width. The playground may extend into the mandatory open space of the plot.
### 1.11.2 Community Space for a Group of Buildings in One Plot
#### 1.11.2.1
For all plots on which more than one residential or residential-cum-business buildings are constructed, community space at the rate of 5% of the total floor area of all the buildings shall be provided either within the buildings or outside within the premises. Roofs of such buildings shall not be considered as community open spaces.
#### 1.11.2.2
A single storeyed structure such as a pavilion not exceeding 25 m² in area shall be permitted to be constructed in such community spaces, which area shall be excluded from the FAR calculations. No toilet block shall be permitted in such a structure.
#### 1.11.2.3
Each community area or the structure built thereon shall be accessible either directly from each building on the plot or by an independent means of access.
#### 1.11.2.4
No building shall extend beyond 3 m of the boundary of the community space.
#### 1.11.2.5
Such community open spaces shall cater only to the needs of the immediate community contiguous to the open space and shall not be made available for use of outsiders.
### 1.11.3 Community Open Space for Industrial Buildings
A minimum of 10% of the total area but not exceeding 0.25 hectare of every industrial plot having an area of 1.0 hectare or more, shall be reserved as community open space. Such area shall be contiguous and shall have a means of access from every unit of the industry for recreational activities of the persons working in the industry.
### 1.11.4 Community Open Space Zones in Area Layouts
#### 1.11.4.1 Residential or Business Areas
In dividing any land measuring a total of 0.4 hectares or more into residential or business plots, community open spaces shall be reserved for recreational purposes of the population for which the layout is planned. The minimum requirement of open spaces in a layout shall be as follows:
a) 15% of the area of the planned layout, or
b) 2000 m² for every 1000 persons. For approved low income housing schemes this limit may be reduced to 1000 m² for every 1000 persons.
The community open space in residential or business layouts shall as far as practicable be provided in one place or planned out to serve the community in clusters or groups. No such community open space plot shall be less than 400 m² in area. The shape of the plot shall be such that the length is not more than 2.5 times its width.
#### 1.11.4.2 Industrial Areas
In dividing any land measuring a total of 1 hectare or more into industrial plots, 5% of the total land area shall be reserved as amenity open space which shall be used as lawn, park or garden. The minimum size of such open space shall be 600 m². When the area of the open space exceeds 1000 m², the area of land in excess of 1000 m² can be used for the construction of buildings for banks, clinics, welfare centres and other common facilities for use of the persons working in the industries.
## 1.12 Requirements of parts of buildings
### 1.12.1 Plinth and Formation Levels
The plinth and formation levels of the building and the plot shall conform to the requirements of Sec 1.5.3.
### 1.12.2 Room Dimensions
#### 1.12.2.1 Ceiling Heights
a) All habitable rooms in non-air-conditioned residential and business & mercantile buildings, apart from kitchen, store room, utility room, box room and garage, shall have a ceiling height not less than 2.75 m measured from the finished surface of the floor to the under side of the finished ceiling, or false ceiling. A maximum of one-third of the floor area of such habitable rooms may, however, have a minimum ceiling height of 2.44 m. For air-conditioned rooms in such buildings, the minimum ceiling height shall be 2.44 m.
In the case of pitched roof without a horizontal ceiling the lowest point of the finished ceiling shall be at least 2 m above the finished surface of the floor and the average height of the ceiling shall not be less than 2.44 m.
b) The minimum clear head room under the ceiling, folded plate, shell etc. and under the false ceiling or duct in an air-conditioned room shall not be less than 2.44 m. The minimum clear distance between the floor below and the soffit of a beam shall not be less than 2.15 m.
c) The requirements of ceiling height for buildings of occupancy other than residential and business & mercantile shall be as follows:
| Occupancy | Minimum Ceiling Height |
| -------------------------------------------------- | ---------------------------------------------------------------------- |
| Educational, Institutional, Health Care, Assembly. | 3 m for non-air-conditioned and 2.6 m for air-conditioned buildings. |
| Industrial, Storage, Hazardous. | 3.5 m for non-air-conditioned and 3.0 m for air-conditioned buildings. |
#### 1.12.2.2 Room Sizes
Every dwelling unit in a residential building shall have at least one room which shall have not less than 9.5 m² of floor area with a minimum width of 2.5 m. Other habitable rooms in the dwelling unit shall have a minimum area of 5 m² each with a minimum width of 2 m.
### 1.12.3 Kitchen
#### 1.12.3.1
The minimum clear height of kitchen measured from the finished surface of the floor to the finished ceiling shall be 2.75 m, except for any floor trap of the upper floor which shall have a minimum clearance of 2.15 m above the finished floor. The minimum clear height of kitchen shall be 2.15 m where mechanical exhaust is installed.
#### 1.12.3.2
The minimum floor area of kitchen without provision for dining shall be 4 m² with a minimum width of 1.5 m. The minimum floor area of a kitchen which is intended to provide dining or occasional sleeping space shall be 7.5 m² with a minimum width of 2.2 m.
#### 1.12.3.3
Every kitchen shall be provided with a kitchen sink or other means for washing utensils. The waste water shall be discharged into the waste water pipe or drain.
#### 1.12.3.4
The floor of the kitchen shall be water tight.
#### 1.12.3.5
Every kitchen shall be provided with window having a minimum area of 1 m² which shall open to the exterior or to an interior open space of adequate dimensions (see Sec 1.7.11).
### 1.12.4 Bathroom and Toilets
#### 1.12.4.1
The height of any bathroom, toilet or water closet shall not be less than 2.15 m measured from the finished floor surface to the finished ceiling or false ceiling or to the lowest point of any trap of the upper floor's plumbing system.
#### 1.12.4.2
The minimum floor area of a bathroom where water closet and bathing facilities are combined shall be 2.8 m² with a minimum width of 1 m. For bathrooms without water closet, the minimum area shall be 1.5 m² with a minimum width of 1 m. The minimum area of a toilet with water closet only shall be 1.2 m² with a minimum width of 1 m. Three fixture bathrooms containing bathing, hand washing and water closet facilities shall have a minimum area of 3 m² with a minimum width of 1.25 m.
#### 1.12.4.3
No bathroom or toilet containing water closet shall open directly into any kitchen or cooking space by a door, window, ventilator, fanlight or any other opening. Every such bathroom or toilet shall have a door completely shutting it off from the exterior.
#### 1.12.4.4
Every bathroom, toilet and water closet shall be located against an exterior wall or wall on the interior open space (see Sec 1.7.11), except where they are ventilated through an interior lighting and ventilation shaft. Such interior lighting and ventilation shafts shall have the minimum dimensions specified in Table 3.1.12 for different heights of buildings. In addition, shafts for buildings exceeding 6 storeys or a height of 20 m shall be mechanically ventilated. All shafts must be accessible at the ground floor level for cleaning and servicing purposes.
**Table 3.1.12 — Minimum Dimensions of Lighting and Ventilation Shaft**
| Building Height — No. of Storeys | Building Height (m) | Minimum Net Cross-sectional Area of Shaft (m²) | Minimum Width of Shaft (m) |
| -------------------------------- | ------------------- | ---------------------------------------------- | -------------------------- |
| Up to 3 | Up to 11 | 1.5 | 1.0 |
| 4 | 14 | 3.0 | 1.2 |
| 5 | 17 | 4.0 | 1.5 |
| 6 | 20 | 5.0 | 2.0 |
| Over 6\* | Over 20 | 6.5 | 2.5 |
\* Mechanical ventilation of the shaft shall be provided for buildings over 6 storeys high. Shaft dimensions shall conform to mechanical design considerations.
#### 1.12.4.5
Floors of bathrooms, toilets or water closets shall be treated with water repellent material and shall be water tight. All bathroom walls or partitions shall be treated with non-absorbent water repellent smooth impervious finish material to a height of not less than 1 m above the finished floor level. The floor shall be sloped gently towards gratings or openings of the floor traps.
### 1.12.5 Stair case
#### 1.12.5.1 Limiting Dimensions
The minimum width of the staircase for various occupancies shall be as specified in Table 3.1.13.
**Table 3.1.13 — Limiting Dimensions of the Staircase**
| Occupancy | Minimum Width of Stair (m) |
| ------------------------------------------------------------- | -------------------------- |
| A. Residential Buildings — A1 Detached Single Family Dwelling | 1.0 |
| A2 Flats or Apartments | 1.15 |
| A3 Mess, Boarding House and Hostel | 1.25 |
| A4 Minimum Standard Housing | See Appendix A |
| A5 Hotels and Lodging Houses | 1.25 |
| B. Educational Buildings | 1.5 |
| C. Institutional Buildings | 1.5 |
| D. Health Care Buildings | 2.0 |
| E. Assembly Buildings | 2.0 |
| F. Business and Mercantile Buildings — F1 Offices | 1.5 |
| F2 Small Shops and Markets | 1.5 |
| F3 Large Shops and Markets | 2.0 |
| F5 Essential Services | 1.5 |
| All Other Buildings | 1.25 |
#### 1.12.5.2
Combination of the riser and the tread dimensions shall be such that the sum of the riser height and the tread depth shall be between 400 mm and 425 mm with a minimum tread depth of 215 mm and a maximum riser height of 215 mm. The tread depth may include any nosing and any increase due to slant riser faces. The variation between depths of adjacent treads and heights of adjacent risers shall not exceed 5 mm. The difference between the largest and the smallest riser or between the largest and the smallest tread shall not exceed 2 per cent of the respective average dimensions in any flight of stairs.
#### 1.12.5.3
The number of steps in a single flight shall be limited to 15.
#### 1.12.5.4
The minimum clear head room between flights of a staircase shall be 2.15 m. The clear head room may be reduced to 2.03 m for not more than three flights in any staircase.
#### 1.12.5.5
The minimum clear height of any passage below a landing providing access to non-habitable and service spaces shall be 2.03 m. The minimum clear height of all other passages and spaces below a landing shall be 2.15 m.
#### 1.12.5.6
Handrails shall have a minimum height of 0.9 m measured from the nose of stair to the top of the handrail. When children are likely to use the stairs, the balustrade design shall incorporate adequate child safety measure.
### 1.12.6 Mezzanine Floor
#### 1.12.6.1
The total area of mezzanine floors in a building shall not exceed one-third the plinth area of the building. The area of the mezzanine floors shall be included in calculating the FAR.
#### 1.12.6.2
The clear headroom both over and under the mezzanine floor shall be at least 2.2 m.
#### 1.12.6.3
The lighting and ventilation of the space both over and under the mezzanine floor shall not be obstructed in any way.
### 1.12.7 Lofts
#### 1.12.7.1
The minimum height of a loft shall be 1.5 m and it shall not be used as a habitable space.
#### 1.12.7.2
The minimum height requirements for various rooms specified under Sec 1.12.2, 1.12.3 and 1.12.4 shall be maintained under the loft.
#### 1.12.7.3
A maximum of 25% of the floor area of any room may be covered by a loft, except bathrooms, toilets, water closets, store rooms and corridors where the whole area may have an overhead loft.
#### 1.12.7.4
The loft shall not interfere with the lighting and ventilation of any room.
### 1.12.8 Cabins or Chambers
#### 1.12.8.1
Cabins or Chambers created by removable partitions on an open floor shall have a minimum area of 3 m².
#### 1.12.8.2
Clear passages at least 0.75 m wide shall be maintained between the cabins leading to a means of exit which shall in no case be further than 16 m from any cabin.
#### 1.12.8.3
A clear gap of at least 300 mm shall be maintained between the top of the partition walls enclosing the cabin and the ceiling, unless the cabin is exposed to the exterior deriving natural light and ventilation or is artificially lighted and ventilated.
### 1.12.9 Store Room
A store room provided in a dwelling unit of a residential building shall have a minimum area of 1.5 m² with a minimum width of 1 m. The clear height of the store room shall not be less than 2.2 m.
### 1.12.10 Private Garage
A private garage in a residential building shall have a minimum clear height of 2.03 m. The length of the garage shall not be less than 4.5 m. The width of the garage for a single car shall be at least 2.6 m and for two cars shall be at least 5 m.
### 1.12.11 Basement
#### 1.12.11.1
Any underground floor of a building wholly or partially below formation level shall be called a basement and shall satisfy the requirements of the following sections.
#### 1.12.11.2
Subject to the provision of Sec 1.8.3.6, the area of the basement shall be included in the calculation of FAR.
#### 1.12.11.3
The walls and floors of the basement shall be damp-proof and waterproof (see Chap 3, Part 6). The basement shall be protected against surface water and drainage waste intrusion.
#### 1.12.11.4
The basement shall have natural lighting and ventilation or shall be artificially lighted and ventilated.
#### 1.12.11.5
The portion of the staircase below the ground floor level shall be secluded by a fire wall or fire separation assembly having a minimum fire resistance time of 2 hours. Independent open staircase and open ramps for access to the basement from the ground floor or the street level shall be permitted.
#### 1.12.11.6
The slope of any ramp provided shall not be steeper than 1 vertical in 8 horizontal.
#### 1.12.11.7
The clear height of the basement below soffit of beams shall not be less than 2.03 m.
#### 1.12.11.8
The floor and the walls of the basement shall be made damp-proof in accordance with the provisions of Sec 3.13 of Part 6.
### 1.12.12 Entrance to the Building
All buildings shall have a covered entrance or other covered area for callers waiting at the door. The main entrance door to the building shall not open into an uncovered exterior.
### 1.12.13 Roof Drainage
#### 1.12.13.1
The roof of a building shall be constructed in such a manner that rain water is drained freely away from the building without causing dampness of the roof or the walls of the building or of an adjacent building.
#### 1.12.13.2
Water from the roof shall not be discharged into the adjacent property or street.
#### 1.12.13.3
For one or two storeyed buildings with flat or pitched roof, rain water may be discharged directly to the ground, in which case the roof shall have extended eaves or cornices to direct the water away from the walls.
#### 1.12.13.4
For other buildings, gutters or parapets shall be provided to direct the water to the piping of an adequate rain water drainage system.
#### 1.12.13.5
The roof shall be impermeable or shall be treated with an impervious material to make it effectively water tight. Flat concrete roofs shall be topped with an impervious layer of lime concrete or other effective means of waterproofing. All flat roofs shall be sloped gently towards gutters, gratings or mouths of the rain water drainage pipes.
### 1.12.14 Parapet
All accessible flat roofs shall be enclosed by parapets or hand rails having a height of at least 1 m. All such parapets and hand rails shall be designed to withstand the lateral forces due to wind and occupancy in conformity with the provisions of Part 6 of this Code.
### 1.12.15 Septic Tank
A septic tank shall be provided within the premises for disposal of sewage, where no public sewer is available. The location, design and construction of the septic tank shall conform with the requirements of Chapter 7, Part 8 of this Code.
## 1.13 Landscaping
### 1.13.1
Plantation of trees and shrubs within the open spaces of a plot aimed at enhancing the environmental quality of the building shall comply with the requirements of this section.
### 1.13.2
Trees and shrubs shall be planted judiciously to meet the requirements of shade and sunshine, to control noise and dust, to provide privacy and to improve visual quality, without jeopardizing natural ventilation and lighting of a building.
### 1.13.3
Species of trees shall be so chosen and planted that their roots do not endanger the building foundation and their branches do not interfere with the building superstructure. This shall be achieved by maintaining sufficient distance between the trees and the building depending on the species of the tree.
## 1.14 Damp-proofing and waterproofing of floors and walls
### 1.14.1
All floors at the ground floor level and all foundation and plinth walls shall be made damp-proof and waterproof.
### 1.14.2
Protective measure shall be taken to eliminate rising damp in ground floor walls by including a RC grade beam at the plinth level. The grade beam may be dispensed with if an approved membrane is applied at the plinth level. If no beam or membrane is provided a damp-proof course (DPC) shall be placed along all the walls at the plinth level. Such damp-proof course shall be made of a rich cement concrete having a thickness of 75 mm and shall be finished with two coats of bitumen.
### 1.14.3
Foundation, floor and walls below grade shall be damp-proofed and waterproofed in accordance with the provisions of Sec 3.13 of Part 6.
## 1.15 Existing buildings
### 1.15.1
Existing buildings and structures in their present occupancy condition shall not be required to be in full compliance with all the requirements of this Code. Additions or alterations to such existing buildings or change of use thereof shall not be permitted if such addition, alteration or change of use is likely to render the building more hazardous with respect to fire safety, life safety and sanitation than it was before.
### 1.15.2
Any horizontal or vertical extension of an existing building or any change of use thereof shall subject the altered building or occupancy to the provisions of this Code for a new building. The building together with the additions and changes shall not exceed the height, area and open space requirements for new buildings specified in this Code.
### 1.15.3
All buildings and structures, both new and existing shall be maintained in a safe and sanitary condition as provided for in this Code. To determine compliance with this requirement, the Authority may cause the building or structure to be periodically inspected.
### 1.15.4
Any proposed change in an existing building or structure shall have to satisfy the requirements set forth in Part 9 of this Code.
## 1.16 Buildings and places of historical or architectural value
### 1.16.1
All historic buildings and places identified, listed and classified so by the appropriate agency of the Government under the Act of Antiquity shall be deemed to be protected. Any change of use, repair, alteration or extension of such buildings shall be in compliance with the requirements of this section and those of the Department of Archaeology of the Government.
Similarly, buildings and works under the jurisdiction of and identified by the Authority as having architectural value shall be exempted from satisfying some of the provisions of this Code as specified in Sec 1.16.2 below. The owner of any such building may also apply to the Building Official for enlistment as a building with architectural value. To be so identified, a building shall have been in existence for at least 20 years from the date of its completion. To determine whether the building or work is architecturally valuable, the Authority shall appoint a standing committee comprising noted experts from the fields of Architecture, Planning, Engineering, History, Art, Literature or any other discipline which may be deemed relevant. The committee shall identify a building as architecturally valuable if, in their judgement, the building possesses distinctive architectural features, has cultural or symbolic value, has become part of the heritage, or bears testimony of some historical event. In addition to satisfying the requirements of Sec 1.16.2 below, any proposed repair, alteration or addition to such buildings must also have the approval of the standing committee who shall have to be satisfied that the proposed changes will not impair the aesthetic quality and architectural character of the building.
### 1.16.2
Repairs, alterations and additions necessary for the preservation, restoration, rehabilitation or continued use or adaptive reuse of such historic buildings and structures, and of buildings and works of architectural value may be exempted by the Authority from having to be in full compliance with all the requirements of this Code, provided that the restored building or structure will be no more hazardous, if any, than the existing conditions in terms of life safety, fire protection and sanitation.
See also Sec 1.5 of Part 1 and Sec 3.8 of Part 2.
## 1.17 Ventilation, lighting and sanitation
### 1.17.1
All rooms and interior spaces designated for human occupancy shall be provided with means of natural or artificial lighting and natural or mechanical ventilation.
### 1.17.2
All buildings shall have water and sanitation facilities as provided for in this chapter and in Chapters 6 and 7 of Part 8.
### 1.17.3
Every kitchen shall have facility for washing of utensils.
### 1.17.4
Every building or independent unit thereof shall be provided with at least one water closet.
### 1.17.5
All naturally ventilated and illuminated interior spaces, staircases and other areas of human occupancy in a building shall have windows or ventilators opening directly to the exterior or an interior open space or to a verandah. Ventilation of bathrooms may also be achieved through ventilation shafts as provided for in Sec 1.12.4.4.
### 1.17.6
All habitable and non-habitable spaces within a building shall have the following minimum aggregate area of openings in the exterior wall, excluding doors, expressed as percentage of the net floor area:
| Space | Minimum Aggregate Area of Openings |
| --------------------------------------------------------------------------- | ---------------------------------- |
| Habitable rooms such as those used for sleeping, living, study, dining etc. | 15% |
| Kitchens | 18% |
| Non-habitable spaces such as bathrooms, store, staircase and other utility | 10% |
#### 1.17.6.1
Notwithstanding the provision of 1.17.6 an enclosed staircase shall have exterior windows not less than 1 m² in area on every floor through which the stairway passes.
#### 1.17.6.2
Toilet and bathroom windows shall open to the exterior or an approved ventilation shaft and the openable area shall not be less than 1 m².
### 1.17.7
The required minimum average intensity of illumination in a habitable space at a height of 750 mm above the floor level shall be 65 lux. Any point in a room more than 7 m away from an exterior window shall be considered to be not illuminated by daylight unless measurement of illumination gives an intensity of 65 lux or more.
#### 1.17.7.1
The required intensity of illumination for various tasks in a building shall be as specified in Chapter 1 of Part 8.
#### 1.17.7.2
Whenever the illumination achieved by daylight is not sufficient or occupancy at night is necessary, artificial lighting shall be installed to supplement daylight, or to provide the required night lighting, in accordance with the provisions of Chapter 1 of Part 8.
### 1.17.8
The requirements of opening areas specified in Sec 1.17.6 shall suffice for ventilation provided that the windows or ventilators forming the opening are openable. When part of the window area is made of fixed glazing, the openable portion only shall be counted in aggregating the opening area.
#### 1.17.8.1
The net clear opening area required for supplying oxygen for breathing shall be taken as 5% of the floor area.
#### 1.17.8.2
Mechanical ventilation, when provided, shall conform to the requirements of Chapter 3 of Part 8.
## 1.18 Air-conditioning and heating
All air-conditioning and heating equipments shall be selected and installed in accordance with the requirements of Chapter 3 of Part 8.
## 1.19 Provision of lifts and escalators
Wherever required by this Code or desired by the owner for comfort, lifts and escalator facilities shall be planned, designed and installed in accordance with the provisions of Chapter 5 Part 8.
## 1.20 Sound insulation
Acoustical design of a building to attain the desired noise levels shall be performed in accordance with the provisions of Chapter 4 of Part 8.
## 1.21 Thermal insulation
Thermal comfort in a building shall be achieved through adequate ventilation and thermal insulation of walls and roof.
## 1.22 Lightning protection of buildings
Lightning protection measures shall be installed on all buildings whose exposure conditions indicate the likelihood of lightning strike and consequential hazard to life and property. Buildings housing explosives or detonators, buildings where a large number of people live or congregate and those that are of strategic or defence importance shall always be protected against lightning strikes. The requirement of lightning protection systems shall be assessed and they shall be designed and installed in accordance with the provisions of Chapter 2 of Part 8.
## 1.23 Rat proofing and termite proofing of buildings
Rat proofing and termite proofing measures shall be undertaken on the basis of the degree of protection desired from rats and termites. Any chemical used for the control of rats and termite shall be free from environmental hazards.
### 1.23.1 Rat Proofing
#### 1.23.1.1
Buildings supported directly on the ground, for which rat proofing is required, shall have continuous foundation walls extending from at least 600 mm below the ground level to at least 150 mm above the ground level. The floor of such buildings shall be of continuous masonry or reinforced concrete or any other effective rat proof construction.
#### 1.23.1.2
Openings in such buildings shall be made rat proof. Doors and windows shall be tight-fitting. Drains, construction joints or other junctions shall be tight-fitting and shall have a protection with grillage or screening or shall be properly closed with metal sheet or masonry or concrete cover.
#### 1.23.1.3
Commercially available chemicals which are repellent or lethal to rats and which do not constitute environmental hazard may be used in buildings according to the manufacturer's instructions.
### 1.23.2 Termite Proofing
The provisions of this section shall apply to buildings where termite infestation may be a problem and measure for protection against termite is considered necessary.
#### 1.23.2.1 Constructional Measures
a) The site of any building shall be cleared of any scrap timber, wooden debris, roots, leaves, stumps or other organic matter. Such debris shall not be buried or accumulated near the building or under the floor or under the foundation.
b) The area underneath the building and its surroundings shall be properly drained and water shall not be allowed to accumulate in such areas. Access of water into these areas from the surroundings shall be effectively prevented.
c) No void or opening or cracks shall be allowed in the foundation or floor or its sub-base. All earth filling in the sub-base and the surroundings shall be free from roots, leaves or other organic matters and properly rammed to prevent any subsidence or formation of voids or cracks. Joints in the foundation or floor or its sub-base shall be properly sealed. Joints in the upper layer shall be staggered from the sub-base.
d) If timber is used in a building, it shall be capable of resisting the attacks of termite or fungi.
e) All masonry works of lime mortar to be exposed to soil shall have a mix ratio of no leaner than 1:3.
f) Vertical joints between the floor and the plinth masonry shall be filled with heavy grade coal tar pitch.
g) In buildings where high degree of termite proofing is necessary, anti-termite construction or termite shields, termite caps or termite grove may be used. (See Appendix B)
#### 1.23.2.2 Pre-constructional Chemical Treatment
a) Termite mounds within the plinth area of a building shall be destroyed with insecticides in the form of water suspension or emulsion. The mound shall be opened at several places onto which suspension or emulsion of the insecticide shall be poured. The mix ratio of the emulsion and the volume of such emulsion to be used may be determined from manufacturer's instructions, or 4 litre for about $1\text{ m}^2$ of the mound may be used with the following emulsions (expressed in concentration by weight):
5 per cent DDT
0.5 per cent BHC
0.25 per cent dieldrin
0.25 per cent aldrin
0.5 per cent heptachlor
0.5 per cent chlordane
b) Complete and continuous chemical barriers may be formed under the whole of the structure to be protected. All foundations shall be fully surrounded by a barrier of treated soil. The barrier shall be formed with commercially available termite repellent chemicals according to the manufacturer's instructions or any of the following chemicals in water emulsion is effective when applied uniformly over the area to be treated:
0.5 per cent dieldrin
0.5 per cent aldrin
0.5 per cent heptachlor
1 per cent chlordane
Treatment of the soil shall be undertaken when excavation is complete and ready for pouring of foundation concrete or laying of form work. (See Appendix B)
Note: The use of chemicals specified in Sec 1.23.2.2 shall be permissible in applications for termite proofing of buildings as long as any of these are not prohibited by the Government for environmental or other reasons for such application. In such cases the relevant chemical shall be deemed to be deleted from the lists given in Sec 1.23.2.2.
#### 1.23.2.3 Treatment for Existing Building
a) Termites detected in a building shall be exterminated by applying oil or kerosene based solution of either dieldrin 0.5 per cent concentration or chlordane 1.0 per cent concentration by weight. Other commercially available chemicals may be used as per instructions of the manufacturer.
b) Existing buildings may be protected against termites by treating the soil adjacent to or under the building with a chemical toxicant that kills or repels termites. One of the emulsions specified in Sec 1.23.2.2(b) or any other environment friendly commercially available chemicals may be used for such termite protection work.
i) The soil in contact with the outer vertical surface of the foundations shall be treated with 15 litre/m² of the vertical surface. Such treatment shall extend up to a depth of 500 mm from the ground level but shall not extend below the top of the footing. Emulsions may be sprayed on the foundation surface by opening trenches or by pouring into holes.
ii) The soil below any opening in the floor through which termites are likely to seek entry into a building shall be treated with emulsions. Holes of diameter 12 mm at an interval of 300 mm shall be drilled in the floor along cracks, construction joints or any other opening and emulsions shall be pumped in until refusal or up to a maximum of 1 litre per hole.
iii) For protection of masonry walls against termites, holes shall be made on such walls on both sides at critical points like wall corners and where door and window frames are embedded in the floor or wall at 300 mm interval. The holes shall have a downward slant of 45° through which emulsions shall be applied with a manually operated pump till refusal or to a maximum of 1 litre per hole. The holes shall be sealed after the treatment.
### 1.23.3 Inspection
Periodic inspections shall be undertaken for effective protection against rats and termites.
## 1.24 Requirements for buildings in flood prone and coastal regions of Bangladesh
The specifications of this section shall be applicable to all buildings located in the flood or surge prone areas in addition to other requirements of this Code.
a) The planning and development control authority of the city, township, municipality or region where this Code is intended to be applied shall delineate any area having a potential for being flooded under at least 1 m deep water due to flooding as Flood Prone Area (FPA). The provisions of Sec 1.24.1 shall be applicable to areas designated as FPA. There shall be a design flood level in the FPA's which shall be recommended by the Authority to be used in interpreting the provisions of this section.
b) Similar delineation shall be made in the coastal regions on the basis of expected occurrence of a surge or wave run-up of 1 m or higher. Such areas shall be designated as Surge Prone Area (SPA). The provisions of Sec 1.24.2 shall be applicable to buildings located in the SPA's. There shall be a design surge height in the SPA's which shall be recommended by the Authority to be used in interpreting the provisions of this section.
### 1.24.1 Flood Prone Areas
#### 1.24.1.1 Elevation
The lowest floor including the basement of any building located in the FPA shall not be located below the design flood level. For buildings of height two storey or less the roof shall be accessible with an exterior stair. For buildings three storeys or higher, the floor immediately above the design flood level shall be accessible with an exterior stair.
Exceptions:
1. Except for Occupancy A (Residential), any occupancy may have floors below the design flood level in accordance with the provisions of Sec 1.24.1.3.
2. A floor of Occupancy A (Residential) may be constructed below the design flood level provided the building has at least another floor of Occupancy A above the design flood level. Such floors shall comply with the requirements of Sec 1.24.1.2 and 1.24.1.3.
3. Floors which are used only for building access, exits, foyers, storage or parking garages may be located below the design flood level in accordance with the provisions of Sec 1.24.1.2.
#### 1.24.1.2 Enclosures below Design Flood Level
There shall be no enclosed space below the design flood level except for building access, exits, foyers, storage and parking garages. There shall be vents, valves or other openings in the walls of the enclosed spaces which shall equalize the lateral pressure of the water. The bottom of such openings shall not be higher than 300 mm above the finished grade. There shall be at least one opening for each enclosure in a building but the total number of such openings shall be at least two. The total net area of openings for an enclosure shall be at least 0.4 m², or 7 per cent of the floor area of the enclosure, whichever is greater.
#### 1.24.1.3 Flood-resistant Construction
Floors constructed below the design flood level under the provisions of Exceptions in Sec 1.24.1.1 shall comply with the following requirements:
a) Floors and exterior walls of such floors shall have a construction impermeable to the passage of water.
b) Structural components of such floors shall be capable of resisting the hydraulic and buoyant forces resulting from the occurrence of floods at the design flood level. Design requirements in such cases are specified in Chapter 1, Part 6.
c) Vents, openings and valves provided below the design level shall have water-tight closures capable of resisting any structural forces resulting from the occurrence of the design flood.
d) Penetrations made for electrical, mechanical or plumbing installations shall be made water-tight to prevent any penetration of flood water. Sewerage systems having opening below the design flood level shall have a closure device to prevent backwater flow during the occurrence of floods.
### 1.24.2 Surge Prone Areas
#### 1.24.2.1 Elevation
The lowest floor including the basement of any building in a surge prone area shall not be located below the design surge height. For buildings of height two storey or less the roof shall be accessible with an exterior stair. For buildings three storeys or higher, the floor immediately above the design surge level shall be accessible with an exterior stair.
Exception:
Footing, mat or raft foundations, piles, pile caps, columns, grade beams and bracings may be constructed below the design surge height.
#### 1.24.2.2 Enclosures below Design Surge Height
Spaces of a building in the SPA's below the design surge height shall not obstruct any flow of water during the occurrence of surge.
Exception:
Structural or non-structural members serving as entries or exits may be constructed below design surge height.
#### 1.24.2.3 Foundations
Foundations of the buildings erected in the SPA's shall be located well below the ground level so that they are safe from erosion or scour during the occurrence of surge. If piled foundations are used, they shall be designed to withstand with adequate factor of safety the loss of support due to scour. Design of the foundations shall conform to the requirements of Chapter 3, Part 6.
# Chapter 2: Classification of Buildings Based on Occupancy
Source: https://docs.sayed.app/bnbc2006/part-3-general-building-requirements-control-and-regulation/chapter-2-classification-of-buildings-based-on-occupancy
## 2.1 OCCUPANCY CLASSIFICATION
Every building shall be classified according to its use or the character of its occupancy as a building of
Occupancy A, B, C, D, E, F, G, H, J or K as defined below :
Occupancy A : \_ Residential
Occupancy B : Educational
Occupancy C : \_ Institutional
Occupancy D : Health Care
Occupancy E : Assembly
Occupancy F : Business and Mercantile
Occupancy G : Industrial
Occupancy H : Storage
Occupancy J: Hazardous
Occupancy K : Miscellaneous
Minor occupancy incidental to operations in another type of occupancy shall be considered as part of the
main occupancy, and shall be classified under the occupancy group relevant for the main occupancy.
Any occupancy not mentioned specifically shall be classified Ps the Authority under the occupancy group to
which its use most closely resembles, considering the potential life and fire hazard.
Each occupancy group shall be subdivided as detailed in the following sections. The example provided for
each occupancy group are nonexhaustive and indicative only. If there is any use or character of occupancy
in a building which is not mentioned here, it shall be classified by the Authority.
Part 3 General Building Requirements, Control and Regulation
### 2.1.1 Occupancy A : Residential Buildings
Buildings classified under this Occupancy shall include all buildings that provide sleeping and living
accommodations to related or unrelated groups of people, with or without cooking or dink facilities,
except any building classified under Occupancy C or D. This Occupancy shall be subdivided as fellowes:
Al DETACHED SINGLE FAMILY DWELLING : These shall include any building, detached from
neighbouring buildings by distances nye paps by this Code, and having independent access, which is
used for private dwelling by members of a single family. ,
A2 FLATS OR APARTMENTS : These shall include any building or portion thereof or group of buildings
in which a | quarters are provided for more than one family, living independently of each other,
with independent cooking facility for each family. Flats or apartments may be located in walk up
buildings, high rise buildings or in housing complexes.
A3 MESS, BOARDING HOUSES, DORMITORIES AND HOSTELS : These shall include any building in
which sleeping and living accommodations are provided for groupe of unrelated persons, with or
without common dining facilities, and with common cooking under management control or with
individual or group cooking facilities, for example, mess houses, dormitories, boarding houses,
hostels and students’ halls of residence.
A4 MINIMUM STANDARD HOUSING : These shall include any building in which one or more families
are housed, specifically built for minimum standard accommodation of lower income families, in
which the minimum requirements for hygiene and safety are maintained, for example, multi-storeyed
complexes, cluster houses and rehabilitation housing or housing undertaken by private low income
groups approved by the Authority.
‘ A5 HOTELS AND LODGING HOUSES : These shall include sas building or group of buildings under
single management, in which sleeping and living accommodation, with or without dining facilities
but without cooking facilities for individuals, is provided for hire on transient or permanent basis, for
example, hotels, motels, rest houses, lodging and rooming houses, inns, and clubs.
### 2.1.2 Occupancy B : Educational Buildings
Buildings classified under this Occupancy shall include all Lie pare in which education and care are
provided to children or adults. This Occupancy shall be subdivided as follows :
B1 EDUCATIONAL FACILITIES : These shall include any eg or portion thereof used for purposes
involving assembly for instruction, education and recreation of more than six persons, and which is
not covered by occupancy E, for example school, college, university class rooms, lobbies and related
facilities, coaching centres, tutorial homes etc.
B2 PRESCHOOL FACILITIES : These shall include any building or portion of a building used for
purposes involving care and education of children more than six in number, for example, day-care
centres, nurseries, kindergartens and other preschool facilities.
### 2.1.3 Occupancy C : Institutional Buildings
Buildings classified under this Occupancy shall include those used for purposes of institutional care of the
occupants, such as medical or nursing care of persons suffering from physical or mental illness or infirmity,
care of infants, orphans, convalescents or old persons, and care and detention for correctional or penal
purposes where the personal liberty of the inmates is restricted. These buildings shall ordinarily provide
sleeping accommodation for the occupants. This occupancy shall be subdivided as follows :
Cl \_ INSTITUTIONS FOR CARE OF CHILDREN : These shall include ay, building or portion thereof or
group of buildings under single management used as an institution for the full time care of children,
including in a each Fee enact ake than six children, for example, child care
institutions and orphanages, Lillah boarding, child care homes and school hostels.
C2 CUSTODIAL INSTITUTIONS FOR THE PHYSICALLY CAPABLE : These shall include my building
or eae thereof or group of buildings under single management used for Lee ape of full time care
and custody of old or ene disabled acl es hear 2 capable of responding to emergency, for
example, home for the aged, home for the care of mentally disabled persons in which the personal
liberty of the inmates is not restricted, and convalescent home for locomotory patients.
C3 CUSTODIAL INSTITUTIONS FOR THE INCAPABLE : These shall include any building or portion
thereof or group of buildings under single management used for purposes of full time care and
custody of persons physically or mentally incapable of responding to emergency, for example, home
for the old and infirm persons not capable of self preservation in an emergency, convalescent home
for non locomotory patients, and mental institution without detention facilities.
C4 PENAL AND MENTAL INSTITUTIONS : These shall include any building or portion thereof or
roup of poe under single management used for OES pore under restraint, or who are
Boiied for penal and corrective purposes, in which personal liberty of the inmates is restricted, for
i I ES a a el
example, jails, prisons, mental hospitals and psychiatric sanatoria with detention facilities, Borstals
and reformatories.
### 2.1.4 Occupancy D : Health Care Buildings
Buildings under this Ign xr group shall include those used for purposes of providing medical care and
treatment to persons, in which sleeping accommodation may or may not be provided. This Occupancy shall
be subdivided as follows :
D1 NORMAL MEDICAL FACILITIES : These shall include ed building or portion thereof or group of
buildings under single management in which general and specialized medical, ala and other
treatment is provided to persons suffering from Beye limitations because of health, for example,
hospitals, nursing homes, clinics, dispensaries, infirmaries and sanatoria.
D2 EMERGENCY MEDICAL FACILITIES : These shall include any building or portion thereof used for
purposes of providing essential medical facilities having reg emergency and casualty treatment
areas, which is Da se and designated to handle post disaster panes! pet and is required to
remain operational after disasters, for example, emergency and casualty units of designated hospitals,
and clinics and dispensaries built as part of a disaster preparedness programme.
### 2.1.5 Occupancy E : Assembly Buildings
Buildings under this gray apc group shall include any building or portion thereof in which groups of pore
congregate or assemble for recreation, amusement, social, religious, political, cultural, travel and similar
purposes, for example, cinemas, theatres, assembly halls, auditoriums, mosques and other places of worship,
ig halls, exhibition halls, museums, art galleries, epee stadiums, restaurants, club rooms, dance
alls, recreation piers, passenger stations and terminals of rail, bus, air and marine transportation systems,
community centres and lecture halls. This Occupancy shall be subdivided as follows :
El LARGE ASSEMBLY WITH FIXED SEATS : This occupancy shall include assembly buildings
provided with a stage and with fixed seats for 1000 or more persons. Assembly buildings under this
subdivision shall be primarily meant for theatrical, operatic or cinematic performances having a
raised stage, proscenium curtains, scenery loft or projection screen, lights, projection booth and
necessary theatrical and mechanical equipment. a Se of this Occupancy are, large theatres,
cinema halls, auditoriums and similar large assembly halls meant for presentation of the performing
arts.
E2 SMALL ASSEMBLY WITH FIXED SEATS : This occupancy shall include any building primarily
meant for use as described for buildings under Occupancy E1, but with fixed seats for less than 1000
persons. These assembly buildings may or may not be provided with a legitimate theatrical stage or
related accessories or equipment. aeest. ya of this sens ope are, small and medium sized theatres,
cinema halls, auditoriums, churches with fixed pew, seminar halls and other assembly halls.
E3 = LARGE ASSEMBLY WITHOUT FIXED SEATS : This Poa ney shall include any assembly building,
its lobbies, foyer, corridors and other related spaces, in which there are no fixed seats, which may or
may not be provided with a legitimate stage or theatrical accessories, and which has accommodation
for 300 or more persons, for example, mosques, prayer halls and other places of worship, lecture
halls, waiting lounges, museums, art galleries, dance halls, restaurants, night clubs, library reading
rooms and lending counters, passenger terminals, exhibition halls and halls for incidental picture
shows or dramatic or theatrical presentations.
E4 SMALL ASSEMBLY WITHOUT FIXED SEATS : This shall include any building primarily intended
for use as described in Occupancy E3, but with accommodation for less than 300 persons.
E5 SPORTS FACILITIES : This shall include any building meant for assembly of people for recreational,
amusement and sporting purposes, for pec ae stadiums, reviewing stands, indoor stadiums, sports
centres, indoor facilities of amusement parks, and indoor swimming pools and gymnasiums with
spectator gallery.
### 2.1.6 Occupancy F : Business and Mercantile Buildings
Buildings under this Occupancy group shall include any building or portion thereof which is used for
transaction of business, display and sale of merchandise, and keeping of accounts and records. This
Occupancy shall be subdivided as follows :
Fl OFFICES : These shall include any building or part thereof which is used as offices, banks and
professional establishments such as architect and engineer's offices, lawyer's and doctor's chambers,
air dressing saloons and beauty parlours, research establishments and test laboratories involving
low hazard materials, computer installations.
F2 SMALL SHOPS AND MARKETS : These shall include any building or portion thereof used for
purposes of display and sale of merchandise, either wholesale or retail, with or without incidental
storage and service facilities, with an area not exceeding 300 m?, for example, shops, stores and
markets.
F3 LARGE SHOPS AND MARKETS : These shall include any building or portion thereof used for
purposes of display and sale of merchandise, either wholesale or retail, with or without incidental
storage and service facilities, with an area more than 300 m?, for example, large shops, markets,
departmental stores, supermarkets and hyper markets.
F4 GARAGES AND PETROL STATIONS : These shall include any beers | or portion thereof used for
providing services moderately hazardous in nature, for example, petrol pump stations, automobile
garages, and aircraft hangars without repair services.
F5 ESSENTIAL SERVICES : These shall include any building or portion thereof used for purposes of
eggitocsl Langs’ vo services and utilities which are required to remain operational after a disaster
or in other emergency situations, for example, police stations, fire stations, TV, radio,
telecommunication and air terminal ae. fates stations and other utilities designated to
provide post disaster emergency services, and buildings having critical national defence capabilities.
### 2.1.7 Occupancy G : Industrial Buildings
Buildings under this Occupancy group shall include any building or portion thereof in which materials are
fabricated, assembled, or processed by physical, chemical, pharmaceutical, nuclear, mechanical and other
processes, in order to alter their characteristics or to produce or manufacture new materials. Such buildings
bane also house incidental storage and handling of the raw and the finished materials or goods. Examples of
such buildings are various mills, factories and plants, automatic laundries, power plants, pumpin; stations,
smoke houses, saw mills, foundries and machine shops, pharmaceutical, nuclear and irradiation hats,
Buildings under this Occupancy shall be subdivided on the basis of hazard potential of the contents and the
processes of the industry. The potential hazard of the Gigs Fame for the purpose of the Code, shall be
determined by the pacha on the basis of the character of the contents and the processes or operations
conducted in the industry. The hazard shall generally mean the relative danger of the start of fire and the
rapidity of its spread, the danger of smoke and gases generated, the danger of Lovee contamination,
radiation sepe and infection, and the od of oe losion and other occurrences that pose a potential
threat to the safety of the occupants of the building. Where the combustibility of the building structure, the
flame spread rate of interior finishes and fittings, or other potential hazards integral to the type of
construction of the building, constitute a greater degree of hazard than that associated with the contents or
processes of the industry, the greater degree of hazard shall dictate the classification. Unless areas with
different degrees of hazard are effectively segregated and separated in accordance with the provisions of the
Code, the most hazardous area ina building shall govern its classification. The Industrial tecapency group
shall be subdivided as follows :
G1 LOW HAZARD INDUSTRIES : These shall include any industrial building in which the contents are
of such low combustibility and the processes conducted therein are of such low hazardous nature
that danger of pi a and self-propagation of fire is nonexistent, the only danger being an onset
of fire from external sources with the Heute danger to life and property arising only from panic,
fumes or smoke.
G2 MODERATE HAZARD INDUSTRIES : These shall include any industrial building in which the
contents are moderately combustible and the industrial processes conducted therein are liable to give
rise to a fire which will spread with moderate rapidity, giving off considerable smoke, but in which
the danger of toxic fumes, biological contamination, radiation or explosions is non-existent.
### 2.1.8 Occupancy H : Storage Buildings
Buildings under this Occupancy group shall include any building or portion thereof used primarily for
storage or sheltering, including incidental servicing, processing or repairs, of goods, wares, merchandise,
vehices or animals. Goods, wares and merchandise stored in Buildings of this ray Sead group, shall be
nonexplosive and shall not involve highly combustible or self-igniting substances. Storage buildings are
characterized by a relatively small number of human occupants in proportion to the area. Incidental storage
auxiliary to other uses shale render a building to be classified as storage building.
Examples of buildings in this bes sed are, warehouses, godowns, cold storage, freight depots, transit
sheds, truck and marine terminals, silos, barns and stables. This Occupancy shall be subdivided as follows :
H1 LOW FIRE RISK STORAGE : These shall include any building or fees thereof which is used for
storage of materials or other contents which do not constitute the ange of self-ignition, and which
in the event of fire will burn with low to moderate rapidity, for example, cold storage, freight depots,
warehouses or godowns containing low fire risk materials, grain silos, terminals, stables and barns
etc.
H2 MODERATE FIRE RISK STORAGE : These shall include any building or portion thereof which is
used for storage of materials which do not constitute the danger of self-ignition but which in the
event of fire will burn with moderate rapidity, for example, warehouses, godowns or depots
containing high fire risk materials, such as paper, textiles, cotton, jute etc., library stack rooms.
re
Items which shall be deemed to render a building hazardous are specified in Sec 2.13.13 along with the
; exempted amount for each item.
### 2.1.9 Occupancy J : Hazardous Buildings
pranks 3 under this Occupancy group shall include any building or portion thereof which is used for the
storage, handling, processing or manufacture of hazardous materials or yeaa The hazards ay arise out
of handling, processing, manufacture or storage of materials which are highly combustible or sk osive that
burn with extreme rapidity emitting poisonous fumes or smokes, which may produce explosive dust
capable of self-ignition, or which are highly corrosive, toxic or noxious producing flame, fumes, and
tae poisonous, irritant or corrosive pee. and materials which pose biological contamination or
radiation danger. This Occupancy shall be subdivided as follows :
jl EXPLOSION HAZARD BUILDINGS : These shall include any puking or portion thereof which is
used for storage, handling, epg 3 or manufacture of materials and products that present high
explosion hazard or that are highly lammable or combustible, capable of self-ignition and/or salf-
re a of fire. Such materials include explosives, blasting meets, fireworks, black powder,
natural gases, other explosive and combustible gases, rocket propellants, petroleum, kerosene, other
fuel oils and highly flammable liquids.
Jj2 CHEMICAL HAZARD BUILDINGS : These shall include any building or portion thereof which is
used for storage, handling, processing or manufacture of materials and products that are ey
corrosive, toxic, powanoss and epi: sn harmful including corrosive and toxic alkalis, acid or
other liquids or chemicals, producing flame, fumes, radiation, and explosive, poisonous, irritant and
corrosive gases.
Definition of hazard and the amount of such materials which shall be deemed to render a building
hazardous are set forth in Sec 2.13.13.
### 2.1.10
Occupancy K : Miscellaneous Buildings
Buildings under this org es group shall include tere buildings and ancillary structures not covered in
other Occupancy groups. The Occupancy shall be subdivided as follows :
K1 PRIVATE GARAGES AND SPECIAL STRUCTURES : These shall include private garages, carports,
garden sheds and tools sheds, zoo, park and botanical garden structures, bus stops etc.
K2 FENCES, TANKS AND TOWERS : These shall include fences and boundary walls over 1.5 m high,
water tanks and towers.
## 2.2 CHANGE OF USE
No change shall be made in the character of occupancy or use of es building that would Dg itina
different group or in a different subdivision of the wai Py Such changes may be made only when the
building is made to comply with the provisions of this Code for such group of Occupancy.
Exceptions:
a) Change in character of occupancy or use of any building may be made and approved by the Authority without
complying to all the requirements of the new group provided the building is less hazardous, based on life and fire
risk, than the existing occupancy.
b) Changes and extensions in existing buildings may be allowed provided such changes and extensions comply with
Sec 1.15 (Existing Buildings).
## 2.3 MIXED OCCUPANCY
When a building is utilized for more than one occupancy or purpose, each part having a distinct occupan
as defined in Sec 2.1 shall be separated from any other cio él as specilied in Table: 3.2.1. Each pontavet
the building shall ce with the et gor of this Code for the ecepeney it accommodates. If
separations are not provided as specified in Table 3.2.1, the building shall conform to the requirements of
the most hazardous of the occupancies.
![Table 3.2.1]()
### 2.3.1 Nonseparated Uses
The following occupancies are not required to be separated from uses to which they are accessory :
a) Assembly rooms having a floor area not more than 75 m?.
b) The administrative and clerical offices and similar offices not exceeding 25 per cent of the floor area of
the major occupancy and not related to Occupancy J (Hazardous Buildings).
c) Administrative offices, gift wii and other similar uses in Occupancy A (Residential Buildings)
provided the uses do not exceed 10 per cent of the floor area of the major occupancy.
d) Kitchens associated with a dining area.
e) Carports having at least two sides entirely open associated with Occupancy A.
f) Parking or storage of motor vehicles associated with Occupancy F4 (Garages and Petrol Stations).
g) Fuel dispensin, Pune covered with a canopy with pees on at least three sides associated with
Occupancy F2 rail hops and Markets) provided the following conditions exist:
i) The Occupancy F2 is provided with two exits separated by a distance of at least one-half the
maximum diagonal dimension of the building or area to be served and not located in the same
exterior wall.
ii) | The pump islands are located more than 6 meter away from the Occupancy F2.
### 2.3.2 Forms of Occupancy Separations ;
Portions of a building having different occupancies shall be separated with horizontal or vertical or of any
other form of separation as may be required to achieve a complete separation.
### 2.3.3 Types of Occupancy Separation
The occupancy separations shall be classified as follows:
a) Four Hour Fire Resistive : The four hour fire resistive separation shall have no openings therein and
shall provide a fire resistance of at least four hours.
‘ b) Three Hour Fire Resistive : The three hour fire resistive separation shall provide a fire resistance of not ;
less than three hours. The total width of all openings in any one storey shall not exceed 25 per cent of
the length of the wall in that storey and no single opening shall have an area greater than 12 m\*. The
openings shall be protected with a fire resistance assembly providing a fire resistance of at least three
hours.
In case of a floor having a three hour fire resistance rating, the openings shall be protected by vertical
enclosures extending above and below such openings. The walls of such vertical enclosures shall be of a
construction offering at least two hours of fire resistance. All openings in the walls of these vertical
enclosures shall be protected with fire assembly having a fire resistance rating of at least one and one-
half hour.
c) Two Hour Fire Resistive : The two hour fire resistive separation shall be of a construction having a fire
resistance ie of not less than two hours. All openings in such separations shall be protected with a
fire assembly of a fire protection rating of at least one and one-half hour.
d) One Hour Fire Resistive : The one hour fire resistive separation shall be of at least one hour fire
protection construction. All openings in such separations shall be protected with a fire protection
assembly of at least one-half hour fire resistance.
## 2.4 GENERAL REQUIREMENTS OF ALL OCCUPANCIES
24.1 Location on Hie aa
#### 2.4.1.1
All buildings shall have access to a public road or yard on at least one side of the property.
#### 2.4.1.2
Fire separation distance of the exterior wall of a building shall be measured from the building face
to the Ce pede property line. For the purpose of this section, the centre line of an adjoining public way, shall
be considered an adjacent prope line. For two buildings on the same plot an imaginary line equidistant
from both buildings shall be considered as the relevant property line.
#### 2.4.1.3
The exterior walls shall have a fire resistance and opening protection as specified in
Tables 3.2.2 and 3.2.3 and in accordance with such additional provisions as are set forth in Part 4.
#### 2.4.1.4
Projection beyond exterior building line shall be limited to the sunshade line as specified in
Sec 1.7.12.4.
#### 2.4.1.5
When openings in exterior walls are required to be protected due to distance from the prpeny
line, the aggregate area of such openings shall not exceed 50 per cent of the total area of the wall in eac!
storey.
### 2.4.2 Allowable Floor Areas
#### 2.4.2.1
The total area of the building shall comply with Sec 1.8.3.
#### 2.4.2.2
The area of the mezzanines shall be included in the area of the floor where the mezzanines are
located, unless they are considered as separate floors.
Part 3 ‘
General Building Requirements, Control and Regulation :
#### 2.4.2.3
A basement floor area need not be included in the total available area of the building provided it is
used for car parking, electrical or mechanical plant or service room. For other uses or occupancies in the
basement, the floor area shall be included in the total area of the building.
Table 3.2.2
Fire Resistance Ratings of Exterior Walls (in hours) for Various Occupancy Groups
(See Sec 3.18 for exceptions)
Distance Al, A2, A4 A3, A5, F3, F4, F5, H2,J |
K1, K2 B,C, D,E, G2,H1 |
Fi, F2,G1 |
Up to 1.5m il 1 4 |
Greater than 1.5m N L 1 2 3 |
and up to3m ]
Greater than 3m N N N 1 2
and up to 4.5m |
Greater than 4.5m N N N N 1
and up to9m |
Greater than 9m N N N N N
|
Table 3.2.3
Requirements for Opening Protection Zeon Based on Fire Resistance |
Rating of Exterior Walls
Fire Resistance Rating of Wal Fire Resistance Required for |
(in hours) Opening Assembly (in hours)
4 Not permitted
3 3
2 ES
1 0.5
N No requirements
### 2.4.3 Permitted vee of Construction
The types of construction for any occupancy shall conform to the specifications set forth in Table 3.2.4.
Table 3.2.4 |
Permitted Types of Construction and Fire Zones for Various Occupancy Groups |
Occupancy Permitted Types o! Fire Zone
Construction |
A |
Cc |
D 12ers: 1
E
F1, F2, F3
H1
K
F4, FS
G lor2 2
H2
\[ot ee (oe en Se ee
## 2.5 REQUIREMENTS OF OCCUPANCY A - RESIDENTIAL BUILDINGS
Buildings shall be classified as Occupancy A in accordance with Sec 2.1.1.
### 2.5.1 Construction, Height and Allowable Area
#### 2.5.1.1
Buildings or pons thereof classified as Occupancy A shall be limited to the Re of construction set
forth in Table 3.2.4 and shall not exceed in area or height as specified in Sec 1.8 and 2.4.2.
|
#### 2.5.1.2
Walls and floors separating dwelling units in the same building shall not be of less than one-hour
fire resistive construction.
#### 2.5.1.3
Storage or laundry rooms in Occupancy A2, A3 or A5 that are used in common by the occupants
shall be separated from the rest of the building by at least one hour fire resistive occupancy separation.
#### 2.5.1.4
When the basement or ground floor of a building of Sige gees ! A2 or AS is used for posting or
storage of private cars of the occupants, the parking floor shall be of Type 1 construction and shall be
separated from the floor above with a three hour occupancy separation.
### 2.5.2 Location on Property
Buildings of Occupancy A shall comply with the requirements for location on property and fire resistive
exterior walls and openings as specified in Sec 2.4.1.
### 2.5.3 Access and Exit Facilities and Emergency Escapes ;
#### 2.5.3.1
Facilities for access and exit shall comply with the provisions set forth in Sec 1.6, and Chapter 3,
Part 4.
#### 2.5.3.2
Every sleeping room in ground, first and second floors shall have at least one openable window or
door for emegency. acces which shall open dyectty into the exterior or an interior courtyard. The units
shall be openable from the inside without the use of any tool to provide a minimum clear opening of 500
mm width by 600 mm height with a maximum sill height of 1 m above the floor.
### 2.5.4 Lighting, Ventilation and Sanitation ;
Daylighting and natural ventilation along with artificial ippting and mechanical ventilation required by this
Code are specified in Sec 1.17 and Chapters 1 and 3, Part 8.
### 2.5.5 Minimum Dimensions of Habitable and Nonhabitable Rooms
The minimum dimensions of habitable and nonhabitable rooms are specified in Sec 1.12.2. The minimum
dimensions of A4 housing (Minimum Standard Housing) are specified in Appendix A.
### 2.5.6 Smoke Detectors and Sprinkler Systems
The ae Gees for smoke detectors and sprinkler systems are specified in Chapters 4 and 5 Part 4 and
those shall be installed according to manufacturer's instructions.
### 2.5.7 Shaft and Exit Enclosures
Elevator shafts, vent shaft, dumbwaiter shaft, garbage chute and other vertical openings shall be enclosed at
least by a four hour resistive construction. Exit requirements are specified in Chapter 3, Part 4.
### 2.5.8 Fire Alarm Systems
Requirements for fire alarm systems in Occupancy A buildings are specified in Chapters 4 and 5, Part 4. Fire
alarms shall be installed in the following residential occupancies :
a) cae seme A2 (Flats or Apartments) having more than 16 pening units ina seal building or more
than 4 occupancy floors shall be provided with an approved manual or automatic fire alarm system.
b) Occupancy A3 (Mess, Boaading Houses and Hostels) buildings of five storey or more in height or
having an occupant load of 30 persons or more shall be equipped with an approved manual or
automatic fire alarm system
c) Fire alarm systems need not be required for residential buildings of not over two storey in height
provided it has adequate exit facilities.
; d) A5 (Hotels and Lodging Houses) with three storey or more in height or containing 20 or more guest
rooms shall be provided with an approved manual or automatic fire alarm system.
e) Multi-storeyed blocks of Occupancy A4 (Minimum Standard owing) with more than 4 occupancy
floors each accommodating 4 or more dwelling units shall be provided with an approved manual fire
alarm system.
## 2.6 REQUIREMENTS FOR OCCUPANCY B - EDUCATIONAL BUILDINGS
Buildings shall be classified as Occupancy B in accordance with Sec 2.1.2.
### 2.6.1 Construction, Height and Allowable Area
bree or parts of buildings classified as Occupancy B shall be limited to type of construction set forth in
Table 3.2.4 and comply with the provisions of Sec 1.8 and 2.4.2, to meet the requirements of height and area
limitations.
#### 2.6.1.1
For the purpose of this section, the following terminology are applicable:
a) Common Space Condition : A common space condition exists between rooms, spaces or areas within a
building or part of a building which are not separated by an approved smoke or draft barrier.
\| b) Separate Space Condition : A separate space condition exists between rooms, spaces or areas when
separated by approved smoke or draft barrier.
c) Smoke and Draft Barrier : A smoke or draft barrier is a wall or floor or partition with or without
openings therein of such construction that will prevent transmission of smoke or gases through them.
#### 2.6.1.2
Automatic closing fire assemblies installed in separate space conditions shall be activated by
approved smoke detectors.
#### 2.6.1.3
The areas of common and separate space conditions served by one side open corridor or verandah
in a building having a height of not more than 14 m or 4 storeys will not require smoke detectors and
standpipes or sprinkler systems except hazardous laboratories, vocational shops and other similar areas
containing hazardous materials. Such hazardous materials shall not exceed the quantities as specified in Sec
#### 2.6.1.4
Rooms or groups of rooms sharing a common space where flammable liquids, combustible dust or
hazardous materials are used, stored, developed or handled in an amount exceeding that specified in Sec
2.13.1.3 shall be classified as Occupancy J. Such rooms or groups of rooms shall comply with the
requirements of fire protection as specified in Chapters 4 and 5, Part 4.
#### 2.6.1.5
Rooms or groups of rooms, sharing a common space or having separate spaces, served by a
common corridor or passage with less than 20 per cent outdoor opening of wall in a building of height 11 m
or less, or three storeys or less, need not be provided with smoke detectors and standpipe or sprinkler
system for fire protection provided it conforms with the access and exit requirements specified in Sec 1.6,
and Chapters 4 and 5, Part 4.
#### 2.6.1.6
Buildings of Occupancy B situated outside the jurisdiction of any municipality shall have a
construction of at least two hours fire resistance.
### 2.6.2 Location on Property
Buildings of Occupancy B shall varud with the requirements for location on property and fire resistive
exterior walls and openings as specified in Sec 2.4.1.
### 2.6.3 Access and Exit Facilities and Emergency Escapes
Facilities for access and exit and emergency escape shall comply with the provisions set forth in Sec 1.6;
Chapter 3, Part 4.
'
### 2.6.4 Lighting, Ventilation and Sanitation
#### 2.6.4.1
yee ventilation and sanitation facilities provided in all Occupancy B buildings shall conform |
to Sec 1.17, and Chapters 1 and 3, Part 8.
#### 2.6.4.2
The ratio of number of water closets to number of students shall be as follows:
bat Girls
| School Level | Boys | Girls |
| :------------------------------ | :---: | :---: |
| For primary schools | 1:100 | 1:35 |
| For secondary schools and above | 1:100 | 1:45 |
In addition to this, urinals shall be provided for boys at the ratio of 1:30 for all schools.
There shall be at least one drinking fountain on each floor.
### 2.6.5 Minimum Dimensions of Class Rooms, Common Toilets and Staircases
The dimension of a class room shall be not less than 4 m on any side and shall have an area of not less than 0.75 m2 per student. Other provisions for minimum dimensions shall comply with the requirements set forth
in Sec 1.8.
### 2.6.6 Shaft and Exit Enclosures
Elevator shafts, vent shafts and other vertical cea shall be enclosed with a construction of at least 3
hour fire resistance. Exit requirements shall comply with Chapter 3 Part 4.
### 2.6.7 Sprinkler and Standpipe System 3
Sprinkler and standpipe systems shall be installed as specified in Chapters 4 and 5, Part 4.
### 2.6.8 Fire Alarm Systems
Requirements for fire alarm systems in Occupancy B buildings are specified in Chapters 4 and 5, Part 4.
## 2.7 REQUIREMENTS FOR OCCUPANCY C - INSTITUTIONAL BUILDINGS
Buildings shall be classified as Occupancy C in accordance with Sec 2.1.3.
:
### 2.7.1 Construction, Height and Allowable Area
The buildings or rao thereof classified as Occupancy C shall be limited to the type of construction set forth
in Table 3.2.4 and shall comply with the provisions of Sec 1.8 and 2.4.2 to meet the requirements of height
and area limitations.
### 2.7.2 Location on Property
Buildings of Occupancy C shall comply with the requirements for location on property and fire resistive
exterior walls and openings as specified in Sec 2.4.1.
### 2.7.3 Access and Exit Facilities and Emergency Escapes
Facilities for access and exit and emergency escape shall comply with the provisions set forth in Sec 1.6, and
Chapter 3, Part 4.
### 2.7.4 Lighting, Ventilation and Sanitation
All bui en: 7 or part of a apres) classified as Occupancy C shall conform with the provisions of
Sec 1.17, and Chapters 1 and 3, Part 8.
### 2.7.5 Shaft and Exit Enclosures
Elevator shafts, vent shafts and other vertical teen shall be enclosed with a construction of at least 4
hour fire resistance. Exit requirements shall comply with Chapter 3, Part 4.
### 2.7.6 Sprinkler and Standpipe Systems
Sprinkler and standpipe systems shall be installed as specified in Chapters 4 and 5, Part 4.
### 2.7.7 Fire Alarm Systems
Requirements for fire alarm systems in Occupancy C buildings are specified in Chapters 4 and 5, Part 4.
## 2.8 REQUIREMENTS FOR OCCUPANCY D - HEALTH CARE BUILDINGS
Buildings shall be classified as Occupancy D in accordance with Sec 2.1.4.
### 2.8.1 Construction, Height and Allowable Area
The buildings or parts thereof classified as Occupancy D shall be limited to the type of construction set forth
in Table 3.2.4 and shall comply with the provisions of Sec 1.8 and 2.4.2 to meet the requirements of height
and area limitations.
### 2.8.2 Location on Property
Buildings of Occupancy D shall comply with the requirements for location on property and fire resistive
exterior walls and openings as specified in Sec 2.4.1.
### 2.8.3 Access and Exit Facilities and Emergency Escapes
Facilities for access and exit and emergency escape shall comply with the provisions set forth in Sec 1.6;
Chapter 3 of Part 4.
### 2.8.4 Lighting, Ventilation and Sanitation
All buildings or es of a building classified as Occupancy D shall conform with the provisions of
Sec 1.17, Chapters 1 and 3 of Part 8.
### 2.8.5 Shaft and Exit Enclosures
Elevator shafts, vent shafts and other vertical openings shall be enclosed with a construction of at least four
hour fire resistance. Exit requirements shall comply with Chapter 3 of Part 4.
### 2.8.6 Sprinkler and Standpipe Systems
. Sprinkler and standpipe systems shall be installed as specified in Chapters 4 and 5 of Part 4.
### 2.8.7 Fire Alarm Systems
Requirements for fire alarm systems in buildings of Occupancy A are specified in Chapters 4 and 5 of
Part 4.
## 2.9 REQUIREMENTS FOR OCCUPANCY E - ASSEMBLY BUILDINGS
Buildings shall be classified as Occupancy E in accordance with Sec 2.1.5.
### 2.9.1 Construction, Height and Allowable Area
The buildings or parts thereof classified as Occupancy E shall be limited to the type of construction set forth
in Table 3.2.4 ond shall comply with the provisions of Sec 1.8 and 2.4.2 to meet the requirements of height
and area limitations.
### 2.9.2 Location on Property
Buildings of Occupancy E shall comply with the requirements for location on property and fire resistive
exterior walls and openings as specified in Sec 2.4.1.
### 2.9.3 Access and Exit Facilities and Emergency Escapes
Facilities for access and exit and emergency escape shall comply with the provisions set forth in Sec 1.6,
Part 3 and Chapter 3, Part 4.
### 2.9.4 Lighting, Ventilation and Sanitation
All buildings or Ns of a petty ype as Occupancy E shall conform with the provisions of
Sec 1.17, Part 3 and Chapters 1 and 3, Part 8.
### 2.9.5 Shaft and Exit Enclosures
Elevator shafts, vent shafts and other vertical bs ripe 8 shall be enclosed with a construction of at least 4
hour fire resistance. Exit requirements shall comply with Chapter 3, Part 4.
### 2.9.6 Smoke Detectors
Smoke detectors of approved quality shall be installed in stage area, assembly rooms with more than 50
occupancy load, projection and control rooms, back stage storage and dressing rooms (see Chapter 5, Part 4).
### 2.9.7 Sprinkler and Standpipe Systems
Sprinkler and standpipe systems shall be installed as specified in Chapters 4 and 5, Part 4.
### 2.9.8 Fire Alarm Systems
Requirements for fire alarm systems in Occupancy E buildings are specified in Chapters 4 and 5, Part 4.
### 2.9.9 Stage, Platform, Proscenium Wall and Curtain
#### 2.9.9.1
The specification of this section shall apply to all parts of buildings and structures that contain
stages or platforms and other similar appurtenances as herein defined.
a) Stages : A stage is a three side enclosed or partially enclosed portion of a bes ory, Resor § is designed or
used for presentation of plays or lectures or other entertainment. A stage shall be further classified as
legitimate stage, regular stage and thrust stage. ,
b) Stage, Legitimate : A stage wherein curtains, drops, leg drops, SE lighting devices or other stage
effects are adjustable horizontally or vertically or suspended over head.
c) Stage, Repilar : A stage wherein curtains, fixed drops, valances, scenery and other stage effects are
suspended and are not adjustable or retractable.
d) Stage, Thrust: A stage or platform extended beyond the proscenium line and into the audience.
#### 2.9.9.2
Stage, Legitimate : Legitimate stage shall be constructed as specified in Table 3.2.4, specifying the
type of construction but shall not be less than construction Type 2. The position of the legitimate stage
extending beyond the proscenium opening line shall be permitted to be constructed with two hour fire-
resistive materials.
The floor of the stage may be constructed with one hour fire rating materials. Thickness of a wooden floor
shall not be less than 50 mm.
#### 2.9.9.3
Stage, Regular and Thrust : Regular — and thrust stages shall be constructed yr not less than
two hour fire resistive materials. Wooden floor when required in a stage shall not be less than 50 mm in
thickness with one hour fire resistive rating.
#### 2.9.9.4
All trap doors and any other opening in stage floors shall be equipped with tight fitting solid wood
trap doors with thickness not less than 4) mm.
#### 2.9.9.5
Stage Rigging Loft : The grid iron frame in the loft housing lighting and audio pee gers all the
machinery for flying scenery and fly galleries along with their installations shall be constructed of approved
noncombustible materials.
#### 2.9.9.6
Foot Lights and Stage Electrical Equipment : Foot lights and border lights shall be installed in a
protective cover constructed of noncombustible materials.
#### 2.9.9.7
Trim, Finish and Decorative Hangings : All materials used in moulding and decoration around
the proscenium shall be noncombustible.
#### 2.9.9.8
Proscenium Curtain : The proscenium curtain shall be of approved fire retardant material and
shall protect against passage of flame and smoke for at least 30 minutes.
### 2.9.10
Motion Picture Projection Rooms
Every projection room shall be constructed in conformity with the construction requirements for the type of
the baliding in which the av ei room is located. The wall opening squire’ for projection need not have '
a fire protection assembly but shall be closed with glass or other approved materials.
eee
The floor area of a projection room shall not be less than 8 m? for a single machine. The working space
between the machines when more than one machine are used shall not be less than 0.75 m.
‘ The height of the projection room shall have a minimum clear space of 2.5 m.
### 2.9.11
Sports Facilities
#### 2.9.11.1
Vomiters, Aisles and Exits of Seating Galleries
a) There shall be a minimum of two exits remotely located from each other immediately to the outside for
each balcony or tier. There shall be three exits when seating capacity exceeds 1000 persons and four
exits when it exceeds 4000 persons.
b) There shall be at least 0.6 m? of space per person in the gallery. Minimum width of a seat in the gallery
shall be 0.45 m.
c) There shall be a maximum of 33 seats on each side of the aisle. Maximum width of the main aisles and
the secondary aisles shall be 1.0 m and 0.7 m respectively.
d) Entrance and exits shall be protected by safety railings.
e) Back to back space between two rows of seats shall not be less than 0.80 m.
f) The evacuation time in the galleries shall not be more than 10 minutes.
#### 2.9.11.2
Swimming Pools
a) Any swimming pool used or constructed for the exclusive use by the Occupancy A1 and is available
only to the occupants and private guests shall be classified as a private swimming pool. Any swimming
pool other than private swimming pool shall be classified as a public swimming pool.
b) There shall be at least 1.5 m space between any side of a swimming pool and a rear or side property
lines. For street property lines, this distance shall be at least 2.0 m.
c) Swimming pools shall be sa with overflow provision to remove scum and other materials from
the surface of the water. When water skimmers are used for private pools there shall be one skimming
device for each 50 m? of surface area or fraction thereof.
d) The overflow gutters shall not be less than 75 mm deep and shall be pitched to slope of one unit vertical :
to 50 units horizontal (1:50) toward drains.
e) Public swimming pools shall be so designed that the pool water turnover is at least once every 8 hours.
f) Private swimming pools shall be designed so that there is a pool water turnover at least once every 18
hours.
g) Public swimming pools shall be equipped with filters the capacity of which shall be controlled to filter
140 litres per minute per m/ of surface area. Private swimming pool filters shall not filter more than 230
litres per minute per m? of the surface area.
h) The acidity and alkalinity of the pool water shall be between 7.0 and 7.5.
i) All pacers ¢ systems shall be equipped with an approved hair and lint strainer installed in the
3 system ahead of the pump.
j) All swimming pool and equipment shall be designed to be emptied completely of water and the
discharged water shall be disposed in an approved manner and shall not create problems in the
neighbouring property.
k) Pumps, filters and other mechanical and electrical equipment shall be placed in enclosed spaces and
shall not be accessible to the bathers.
### 2.9.12
Amusement Building Alarm System
An approved smoke detection system shall be installed in an amusement building according to the fire
protection provisions specified in Chapters 4 and 5, Part 4.
### 2.9.13
Public Address System
A public address system may be installed when required to act as alarm system.
## 2.10 REQUIREMENTS FOR OCCUPANCY F - BUSINESS AND MERCANTILE BUILDINGS
Buildings shall be classified as Occupancy F in accordance with Sec 2.1.6.
Part 3 ,
General Building Requirements, Control and Regulation
### 2.10.1
Construction, Height and Allowable Area
The buildings or pra thereof classified as Occupancy F shall be limited to the type of construction set forth
in Table 3.2.4 and shall comply with the provisions of Sec 1.8 and 2.4.2 to meet the requirements of height
and area limitations. F
Special provisions for the buildings of Occupancy F are specified in the following sections.
#### 2.10.1.1
Ground floor or basement of a building used for car parking and separated from the building
above by at least three hour fire resistive construction shall not be iochiaied in the area calculation of the
building nor shall it be included in the calculation of number of storeys provided the floors above
accommodate one or more of the following occupancies:
i) A2, AS
ii) E2, E3, E4
iii): Fi, F2,F3
Entry lobbies, mechanical and electrical rooms and other similar uses incidental to the operation of the
building may be provided in the car parking floor provided the total area of such uses remains within 4 of
the parking floor area.
#### 2.10.1.2
The storage area in Occupancy F2 and F3 in connection with whole sale or retail sales shall be
separated from public area by a one hour fire resistive construction.
Exceptions :
Occupancy separation need not be provided when any one or more of the following conditions prevail:
i) The storage area does not exceed 100 m2,
ii) The storage area is protected with approved sprinkler system and does not exceed 300 m?,
### 2.10.2
Location on Property
Buildings of Occupancy F shall cee. with the requirements for location on property and fire resistive
exterior walls and openings as specified in Sec 2.4.1.
### 2.10.3
Access and Exit Facilities and Emergency Escapes
Facilities for access and exit and emergency escape shall comply with the provisions set forth in Sec 1.6;
\$ Chapter 3, Part 4.
### 2.10.4
pes geen Ventilation and Sanitation
All buildings or pete of a building classified as Occupancy F shall conform with the provisions of
Sec 1.17; Chapters 1 and 3, Part 8.
### 2.10.5
Shaft and Exit Enclosures
Elevator shafts, vent shafts and other vertical openings shall be enclosed with a construction of at least 4
hour fire resistance. Exit requirements shall comply with Chapter 3, Part 4.
### 2.10.6
Highrise Buildings
The provision of this section shall apply to all beilcoe having floors used for human occupancy located
more than 20 m from ground level or the lowest level of fire department vehicle access.
Exceptions :
The provisions of this section may not be required for the following buildings and structures: :
i) Airport traffic control towers notwithstanding other provisions of this Code,
ii) Open parking structures,
iii) Buildings used for low hazard special uses which are approved by the Authority.
#### 2.10.6.1
Maintenance and Inspection: All fire protection systems shall be maintained and pri ona
regular basis to keep them in operative condition. The maintenance inspection shall be performed quarterly.
All plumbing installations shall be maintained and inspected periodically to keep them in operative
ced preg
#### 2.10.6.2
Type of Construction: All highrise buildings shall be of Type 1 construction.
### 2.10.7
Sprinkler and Standpipe System
When required ia other Socmaa of this Code, sprinkler system shall be installed according to the
specifications set forth in Chapters 4 and 5, Part 4.
### 2.10.8
Special Hazards
Installation of pre heating ei impaye boiler, central heating or air-conditioning plant shall conform to
the provisions of this Code as specified in Chapter 3, Part 8.
eee
SSE
### 2.10.9
Open Parking Garages
Open parking garages used exclusively for car parking or storage of private or pleasure type motor vehicles
shall have Type 1 or Type 2 construction.
#### 2.10.9.1
Openings : The exterior opening of a garage structure shall not be less than 20 per cent of the floor
area in any floor.
#### 2.10.9.2
Ramps, exit stair and elevators shall be provided as specified in Sec 1.12, and Chapter 3, Part 4.
### 2.10.10
Helistops
2,10.10.1 General : Helistops on the roof top of a building or other locations shall be constructed in
accordance with this section.
#### 2.10.10.2
Size: The minimum dimension of the lea area for helicopters bape less than 1600 kg
shall be 6 m x 6 m. There shall be an average clearance of 4 m surrounding and at the level of the landing
area which shall not be less than 2 m at any point.
#### 2.10.10.3
Construction : Helicopter landing areas and supports shall be constructed with non-combustible
material.
#### 2.10.10.4
Aviation Approval : Before helistops start operating formal approval shall be obtained from the
civil aviation authority.
### 2.10.11
Smoke Detectors
Smoke detectors of approved quality shall be installed in storage areas of F2 and F3 occupancies and
highrise F1 occupancies.
### 2.10.12
Fire Alarm Systems
Requirements for fire alarm systems in buildings of Occupancy F are specified in Chapter 5, Part 4.
## 2.11 REQUIREMENTS FOR OCCUPANCY G - INDUSTRIAL BUILDINGS
Buildings shall be classified as bags ae | G in accordance with Sec 2.1.7. An nonexhaustive and indicative
list of low hazard and moderate hazard industrial uses are listed in Tables 3.2.5 and 3.2.6 + amealat
Storage and use of hazardous materials shall not exceed the exempt amount specified in Sec 2.13.1.3.
### 2.11.1
Construction, Height and Allowable Area
The buildings or Lae thereof classified as Occupancy G shall be limited to the type of construction set forth
in Table 3.2.4 and shall comply with the provisions of Sec 1.8 and 2.4.2 to meet the requirements of height
and area limitations.
### 2.11.2
Location on Property
Buildings of Occupancy G shall comply with the requirements for location on property and fire resistive
exterior walls and openings as specified in Sec 2.4.1.
### Table 3.2.5: Examples of Low Hazard Industries
| Sl. No. | Description |
| :-----: | :--------------------------------------------- |
| 1 | Beverages, nonalcoholic |
| 2 | Brick and masonry |
| 3 | Ceramic products |
| 4 | Foundries |
| 5 | Glass products |
| 6 | Gypsum |
| 7 | Ice plants |
| 8 | Metal fabricator and assembly |
| 9 | Water pumping plants |
| 10 | Agricultural farms |
| 11 | Grain processing mills (agricultural products) |
| 12 | Silk processing and spinning |
### 2.11.3
Access and Exit Facilities and Emergency Escapes
Facilities for access and exit and emergency escape shall comply with the provisions set forth in Sec 1.6;
Chapter 3, Part 4.
### 2.11.4
Lighting, Ventilation and Sanitation
All buildings or part of a building classified as Occupancy G shall conform with the provisions of
Sec 1.17; Chapters 1 and 3, Part 8.
}
Part 3 i
General Building Requirements, Control and Regulation :
Special provisions: Industrial buildings having roof opening for daylighting and natural ventilation shall
comply with the following requirements:
i) The aggregate opening in roof and external windows shall not be less than 10 per cent of the floor
area.
ii) For natural ventilation by means of exterior window openings, the operable window area shall not be
less than 5 per cent of the total floor area.
Exception :
Industrial buildings wherein artificial lighting and mechanically operated ventilation systems of approved quality are
installed need not be provided with natural ventilation or natural lighting.
### 2.11.5
Shaft and Exit Enclosures |
Elevator shafts, vent shafts and other vertical openings shall be enclosed with a construction of at least 4
hour fire resistance. Exit requirements shall comply with Chapter 3, Part 4.
### 2.11.6
ene and Standpipe System j
en required Les bertaadl el nse of this Code, sprinkler system shall be installed according to the
specifications set forth in Chapters 4 and 5, Part 4.
### 2.11.7 Special Hazards
Chimneys, vents and ventilation ducts shall be constructed with noncombustible materials. Every bailer,
central heating plants, electrical rooms, or hot water supply bailer shall be separated from the rest of the
occupancy or use by not less than two hour fire resistive construction.
### 2.11.8
Fire Alarm Systems
Requirements for fire alarm systems in Occupancy G buildings are specified in Chapters 4 and 5, Part 4.
## 2.12 REQUIREMENTS FOR OCCUPANCY H - STORAGE BUILDINGS
Buildings shall be classified as Occupancy H in accordance with Sec 2.1.8.
### 2.12.1
Construction, Height and Allowable Area
The buildings or pee thereof classified as Occupancy H shall be limited to the type of construction set forth
in Table 3.2.4 and shall comply with the provisions of Sec 1.8 and 2.4.2 to meet the requirements of height |
and area limitations. |
### 2.12.2
Location on Property
The location on property for Occupancy H shall conform with Sec 2.4.1.
### 2.12.3
Access and Exit Facilities and Emergency Escapes
Facilities for access and exit and emergency escape shall comply with the provisions set forth in Sec 1.6;
Chapter 3, Part 4. i
### 2.12.4
Lighting, Ventilation and Sanitation
All buildings or part of a building classified as Occupancy H shall conform with the provisions of
Sec 1.17; Chapters 1 and 3, Part 8.
Special Provision : The provisions of Sec 1.17, does not apply to nonhabitable spaces of H1 and H2 i
occupancies unless otherwise ip nl by this Code. Ventilators of size not less than 0.25 m? shall be |
espe where suitable 0.30 m above the floor level for floor level ventilators and 0.30 m below the roof ]
evel for roof level ventilators. There shall be one floor level ventilator and one roof level ventilator for every
0.25 m? of the floor area. Mechanized ventilation system of approved quality shall be installed where
required.
### 2.12.5
Shaft and Exit Enclosures
Elevator shafts, vent shafts and other vertical oe shall be enclosed with a construction of at least 4
hour fire resistance. Exit requirements shall comply with Chapter 3, Part 4.
### 2.12.6 Sprinkler and Standpipe System
When required by other provisions of this Code, sprinkler system shall be installed according to the
specifications set forth in Chapters 4 and 5, Part 4.
### 2.12.7 Special Hazards
The storage of hazardous materials shall not exceed the exempt amount as specified in Table 3.2.7. The storage of moderate and low hazardous materials shall be separated at least by a two hour fire resistive construction.
## 2.13 REQUIREMENTS FOR OCCUPANCY J - HAZARDOUS BUILDINGS
Buildings shall be classified as Occupancy J in accordance with Sec 2.1.9.
### 2.13.1 General
The plans for buildings and structures accommodating Occupancy J shall clearly indicate the type and intended use of materials and its processing or handling methods so as to reflect the nature of use of each portion of such buildings.
#### 2.13.1.1 Occupancy J1
Any building or portion thereof containing the following shall be classified as Occupancy J1.
a) Any building or portion thereof containing the following shall be classified as Occupancy J1:
* Combustible dusts and any similar solid material sufficiently comminuted for suspension in still air which, when so suspended, is capable of self-sustained combustion.
* Combustible liquids - Any liquid having a flash point at or above 40°C shall be known as class II and class III liquids. Combustible liquids shall be classified as follows:
* Class II Liquids having flash point at or above 40°C and below 60°C.
* Class III Liquids having flash points at or above 60°C and below 95°C.
* Cryogenic liquids (flammable or oxidizing): Any liquid that has a boiling point below -130°C.
* Flammable Gases : Any gas when mixed with air in a proportion of 13% (by volume) forms a flammable mixture under atmospheric temperature and pressure.
* Flammable Liquids : Any liquid that has a flash point below 40°C and has a net vapour pressure exceeding 275 kPa at 40°C. Flammable liquids shall be known as Class I liquid and shall be further classified as follows:
* Class I. A : Liquids having flash point below 25°C and having a boiling point below 40°C.
* Class I. B : Liquids having flash point below 25°C and having a boiling point at or above 40°C.
* Class I. C : Liquids having flash points at or above 25°C and below 40°C.
* Oxidizers class 3 : As determined in accordance with NFPA 43A.
* Oxidizing gases : As determined in accordance with NFPA 43C.
* Pyrophoric liquids, solids and gases that will ignite spontaneously in air at a temperature of 55°C or below.
* Unstable (reactive) materials class 3, nondetonatable as determined in accordance with NFPA 704.
* Combustible fibres: Includes readily ignitable fibres like cotton, sisal, jute hemp, tow, cocoa fibre, oakum, baled waste, baled waste paper, kapok, hay, straw, excelsior, Spanish moss and other similar materials.
* Flammable solid: Any solid including blasting agent or explosive that is liable to cause fire through absorption of moisture, spontaneous chemical change or retained heat from manufacturing or processing, or which when ignited burns so vigorously and persistently as to create a serious hazard.
* Organic peroxides, Class II and Class III as determined in accordance with NFPA 43B.
* Oxidizers Class I and Class II as determined in accordance with NFPA 43A.
* The bulk storage of unstable (reactive) materials Class 1 and Class 2 as determined in accordance with NFPA 704, water reactive materials, Class 2 and Class 3 which react with water to release a gas that is either flammable or present a health hazard as determined in accordance with NFPA 704.
#### 2.13.1.2 Occupancy J2
a) Any building or portion thereof containing the following shall be classified as Occupancy J2:
* Corrosives: Any substance that causes visible destruction of or irreversible alteration in living tissues by chemical action at the site of contact.
* Highly toxic materials: The materials falling in this category are as follows:
i) Oral Toxicity : A chemical that has a median lethal dose of 50 mg or less per kg of body weight when administered orally to albino rats weighing between 200 and 300 gms each.
ii) Toxicity of Inhalation : A chemical that has a median lethal concentration in air of 200 ppm or less by volume of gas or vapour, or 2 mg per litre or less of mist, fume or dust, when administered by continuous inhalation for 1 hour (or less if death occurs within 1 hour) to albino rats weighing between 200 and 300 grams each.
iii) Toxicity by Skin Absorption : A chemical that has median lethal dose of 200 mg or less per kg of body weight when administered by continuous contact for 24 hours (or less if death occurs within 24 hours) with the bare skin of albino rabbits weighing between 2 and 3 kg each.
iv) Irritants : Any noncorrosive chemical or substance which causes a reversible inflammatory effect on living tissues by chemical action at the site of contact.
v) Radioactive Material : Any material or combination of materials that spontaneously emit ionizing radiation.
vi) Sensitizers : A chemical or substance that causes a substantial proportion of exposed people or animals to develop an allergic reaction in normal tissue after repeated exposure to the chemical.
b) The Occupancy J2 shall also include among others the followings:
i) Dry cleaning establishments using flammable solvents.
ii) Explosive manufacturing.
iii) Paint or solvent manufacturing (flammable base).
iv) Pyroxylin plastic manufacturing.
v) Sodium nitrate or ammonium nitrate.
vi) Storage of combustible film.
#### 2.13.1.3 Special Provisions
The following shall not be included in Occupancy J but shall be classified in the occupancy group which they most nearly resemble and such classification shall be approved by the Authority:
i) All buildings and structures and portions thereof which contain less than the exempt quantities as specified in Table 3.2.7, when such buildings comply with the fire protection provisions of this Code.
ii) Rooms containing flammable liquid in tightly closed containers of 4 litre capacity or less for retail sales or private use on the premises and in quantities not exceeding 820 litre/m² of room area.
iii) Retail paint sales rooms with quantities not exceeding 820 litre/m² of room area.
iv) Closed systems housing flammable or combustible liquids or gases used for the operation of machinery or equipment.
v) Cleaning establishments.
vi) Liquor stores and distributors without bulk storage.
vii) Tyre storage containing less than 10,000 vehicle tyres.
viii) The storage or use of materials for agricultural purposes for use on the premises.
ix) Pyrophoric solids or liquids not exceeding 3 m³ in storage cabinet located in a building that is equipped throughout with an automatic sprinkler system provided in accordance with the fire protection provisions of this Code.
x) Pyrophoric solids or liquids not exceeding 3 kg in storage cabinet located in a building that is provided with an automatic sprinkler system installed in accordance with the fire protection provisions of this Code.
xi) Class 2 water reactive materials not exceeding 100 kg in an approved storage cabinet located in a building that is provided with automatic sprinkler installed in accordance with the fire protection provisions of this Code.
### Table 3.2.7: Exempt Amounts of Hazardous Materials
| Sl. No. | Material | Class/State | Maximum Quantities |
| :-----: | :-------------------------------------- | :----------------------------------------------------------- | :--------------------------------------------------- |
| 1. | Flammable liquids | Class I-A
Class I-B
Class I-C | 115 litres\*
230 litres\*
340 litres\* |
| 2. | Combustible liquids | Class-II
Class-III A | 455 litres\*
950 litres\* |
| 3. | Combination of flammable liquids | | 455 litres\* |
| 4. | Flammable gases | | 84,000 litres atmospheric pressure at 21°C |
| 5. | Liquefied flammable | | 230 litres |
| 6. | Combustible fibres | Loose | 2800 litres |
| 7. | Combustible fibres | Baled | 28,000 litres |
| 8. | Flammable solids | | 230 kg. |
| 9. | Unstable materials | | No exemptions |
| 10. | Corrosive liquids | | 210 litres |
| 11. | Oxidizing materials | Gases | 168,000 litres |
| 12. | Oxidizing materials | Liquids | 190 litres |
| 13. | Oxidizing materials | Solids
Class-1
Class-2
Class-3
Class-4 |
1815 kg.
455 kg.
90 kg.
4.5 kg. |
| 14. | Organic peroxides | Class-1
Class-1 & 3 | No exemptions
4.5 kg. |
| 15. | Nitromethane | Unstable materials | No exemptions |
| 16. | Ammonium nitrate | | 455 kg. |
| 17. | Ammonium nitrate | Compound mixtures containing more than 60% nitrate by weight | 455 kg. |
| 18. | Highly toxic material and poisonous gas | | No exemptions |
| 19. | Irritants | | 2270 kg. |
| 20. | Sensitizers | | 2270 kg. |
| 21. | Smokeless Powder | | 9 kg. |
| 22. | Black sporting powder | | 2.3 kg. |
*The maximum quantities may be increased by 100 per cent in areas not accessible to the public in buildings provided with automatic sprinkler system.*
### 2.13.2 Construction, Height and Allowable Area
#### 2.13.2.1
The buildings or parts thereof classified as Occupancy J shall be limited to the type of construction set forth in Table 3.2.4 and shall comply with the provisions of Sec 1.8 and 2.4.2 to meet the requirements of height and area limitations.
#### 2.13.2.2 Floors
The floors and spaces containing hazardous materials and in areas where motor vehicles, boats, helicopters or airplanes are stored, repaired or operated shall be of noncombustible, liquid-tight construction.
Exception :
In floors and areas where no repair works are carried out may be surfaced or waterproofed with asphaltic paving materials.
#### 2.13.2.3
Spill Control : The floors containing hazardous repair or other works shall be recessed a minimum
of 100 mm so as to prevent flow of liquids to adjoining areas.
#### 2.13.2.4
Drainage : The buildings and areas shall be provided with approved drainage system to direct the
Fl flow of liquids to an odie location or room or area designed to provide secondary containment of the
hazardous materials and fire protection water. f
The drains shall be designed with adequate slope and section to carry the design discharge of the sprinkler
system. The material used in the drains shall be suitable for drainage of the storage materials.
Separate drainage system shall be designed for materials which react with each other producing undesirable
results. They may be combined when ey have been provided with approved means of discharge into the
public sewer or natural stream or river.
#### 2.13.2.5
Containment: The outflow from the drains shall be directed to a containment system or other area
that provide a secondary storage for the hazardous materials and bi 4 and fire protection water. The
containment capacity shall be capable of containing the outflow from the drains for a period of at least one
hour.
The overflow from secondary containment system shall be directed to a safe location away from the
building, adjoining properties and storm drain.
If the secondary containment storage area is open to rainfall it shall be designed to accommodate 24 hour
rainfall or a continuous rainfall of 100 mm per dey,
Chapter 2 °
Classification of Buildings Based on Occupancy
#### 2.13.2.6
Smoke and Heat Vents : Smoke and heat vents shall be provided in areas or rooms containing
hazardous materials exceeding the exempt amount of Table 3.2.7.
#### 2.13.2.7
Standby Power : Standby power shall be provided in the occupancies where Class I, II or III
organic peroxides are stored.
### 2.13.3
Location on Property
The location on property for Occupancy J shall conform with Sec 2.4.1.
### 2.13.4
Access and Exit Facilities and Emergency Escapes
Facilities for access and exit and emergency escape shall comply with the provisions set forth in Sec 1.6, and
Chapter 3, Part 4.
### 2.13.5
Lighting, Ventilation and Sanitation é
#### 2.13.45.1
All spaces and rooms customarily occupied by human beings shall be peorided with natural light
by means of exterior see Beda an area of not less than 10 per cent of the floor area. Such rooms and
spaces shall be provided with natural ventilation id means of exterior Sp enioes with an openable area not
less than 5 per cent of the total floor area or artificial light and mechanically operated ventilation system.
#### 2.13.5.2
Ventilation in Hazardous Locations : The rooms, spaces or areas where explosive, corrosive,
combustible, flammable or highly toxic dust, mists, fumes, vapous or gases are stored or may be emitted
due to the processing, use, handling or storage of materials shall be mechanically ventilated.
) The mechanical ventilation of all hazardous uses shall be segregated or separated from the ventilation of ;
other areas. The emissions generated at work areas shall be confined to the area in which they are generated
and shall be removed or discharged outside the building ee peseeee measures against back flow of such
hazardous fumes or gases inside the building shall be installed.
#### 2.13.5.3
Ventilation of Toilets : Toilets shall be provided with fully openable exterior window of at least 0.3
m? in area or a vertical duct not less than 62500 mm? in cross-section for the first water closet, with 31250
additional mm? for each additional fixture or a Saecrrange'? 7, ange exhaust system equipped to provide a
complete change of air in ere 15 minutes. Such system shall be connected to the outside air and the point
of discharge shall be at least 1.0 m away from any other opening into the building.
Other requirements of water closets are specified in Sec 1.11.4.
### 2.13.6
Shaft and Exit Enclosures
Elevator shafts, vent shafts and other vertical cee shall be enclosed with a construction of at least 4
hour fire resistance. Exit requirements shall comply with Chapter 3, Part 4.
### 2.13.7 Sprinkler and Standpipe Systems
When required by other provisions of this Code, sprinkler system shall be installed according to the
specifications set forth in Chapters 4 and 4, Part 4.
### 2.13.8
Explosion Control
Explosion control, equivalent protective devices or sy) bani systems or barricades shall be installed to
control or vent the gases resulting from deflagrations of dusts, gases or mists in a room or area, building or
other enclosures to minimize structural or mechanical damage.
Walls, floors and roofs separating a use from explosion exposure shall be designed according to the
provisions of Chapter 1, Part 6.
Explosion ens shall be designe? in exterior walls or roof only. The venting shall be provided to prevent
serious structural damage and production of lethal al gee The ener design shall recognize the
natural characteristics and behaviours of a ee is in an explosion. The vents shall be designed to
relieve at a maximum internal pressure of 1 kPa but not less than the loads required by Chapter 2, Part 6.
One or more of the following systems shall be installed to relieve explosion, where applicable:
a) Light weight materials in walls.
b) Light fastening devices with hatch covers.
c) Light fastening with outward opening swing doors in exterior walls.
d) Nonbearing walls with light ties.
The Bevinaca nape shall discharge vertically or horizontally directly to an unoccupied yard having a width
of not less than 16 m on the same plot.
The sees devices shall be so located that the discharge end shall not be less than 3 m vertically and 6 m
horizontally from window openings or exits in the same or adjoining buildings.
ee eee
### 2.13.9
Fire Alarm Systems
A manual fire alarm system shall be installed in ay cord J2 and an automatic smoke detection system
shall be installed in rooms, spaces or buildings with Occupancy J1 in accordance with the provisions of
Chapters 4 and 5, Part 4.
### 2.13.10 Special Hazards
Chimneys and vents and ventilation ducts shall be of noncombustible materials.
Every bailer, central heating plants, electrical rooms or hot water supply bailer shall be separated from the
rest of the occupancies or uses by not less than 2 hour fire resistive construction.
The devices that generate a spark, flame or glow capable of igniting gasoline shall not be installed or used
within 0.5 m of the floor.
Equipment or machinery that produces or emits combustible or explosive dust or fibres shall be provided
with an approved dust collecting and exhaust system.
The equipment or system that are used to collect, process or convey combustible dust or fibres shall be
installed with explosion venting or containment system.
## 2.14 REQUIREMENTS FOR OCCUPANCY K - MISCELLANEOUS BUILDINGS
Buildings shall be classified as Occupancy K in accordance with Sec 2.1.10. \
q
### 2.14.1 General
The buildings or parts thereof classified as Occupancy K shall be limited to the type of construction set forth
in Table 3.2.4 and shall comply with the requirements of Sec 1.8 and 2.4.2 to meet the requirements of height
and area limitations. ;
Any building or portion thereof that exceeds the limitations provided in this chapter shall be classified in the |
occupancy group other than K that it most nearly resembles. 4
In mixed occupancy buildings, the exterior wall and opens, eee for K1 occupancy shall follow the
> onal of the major ee of the building. For such mixed occupancy buildings, the allowable
> oor area for Occupancy K1 shall be as permitted for the major occupancy contained therein.
### 2.14.2 Location on Property
The location on property for Occupancy K shall conform with Sec 2.4.1.
### 2.14.3 Access and Exit Facilities and Emergency Escapes
Access and exit facilities for Occupancy K shall comply with the specification set forth in Sec 1.6; Chapter 3,
Part 4.
### 2.14.4 Lighting, Ventilation and Sanitation
All buildings or pa of a building classified as Occupancy K shall conform with the provisions of
Sec 1.17; Chapters 1 and 3, Part 8. 3
### 2.14.5 Shaft and Exit Enclosures
Elevator shafts, vent shafts and other vertical corns shall be enclosed with a construction of at least 4
hour fire resistance. Exit requirements shall comply with the requirements of Chapter 3, Part 4.
### 2.14.6 Sprinkler and Standpipe System
When required by other provisions of this Code, sprinkler system shall be installed according to the
specifications set forth in Chapters 4 and 5, Part 4.
### 2.14.7 Fire Alarm Systems
Requirements for fire alarm systems in Occupancy K buildings are specified in Chapters 4 and 5, Part 4.
### 2.14.8 Special Hazards
Chimneys and exhausts shall be constructed with noncombustible materials.
The garage floor shall be constructed with not less than 4 hour fire resistance materials.
### Related Appendix
| Appendix | Title |
| :------------- | :------------------------------------------------------------------------ |
| **Appendix A** | Guidelines for the Development of Minimum Standard Housing (Occupancy A4) |
# Chapter 3: Classification of Building Construction Types Based on Fire Resistance
Source: https://docs.sayed.app/bnbc2006/part-3-general-building-requirements-control-and-regulation/chapter-3-classification-of-building-construction-types-based-on-fire-resistance
## 3.1 CLASSIFICATION AND GENERAL REQUIREMENTS
### 3.1.1 Classification by Type of Construction
For the purpose of this Code, there shall be three types of construction based on fire resistance which are as follows:
Type 1 : Highest degree of fire resistance
Type 2 : Intermediate degree of fire resistance
Type 3 : Lowest degree of fire resistance
The fire resistance ratings of various types of construction for structural and nonstructural members are specified in Table 3.3.1.
Buildings having a height of more than 20 m shall be constructed with noncombustible materials.
The fire resistance ratings of various building components shall conform to ASTM standards.
![Table 3.3.1: Required Fire Resistance Ratings of Building Elements (in hours) for Various Types of Construction]()
### 3.1.2 Fire Zones
The planning and development authority of the city, township, municipality or region where this Code is intended to be implemented shall divide the area under their jurisdiction into distinct fire zones. The basis for this zoning shall be the fire hazard inherent in the buildings and the degree of safety desired for the occupancy accommodated therein. The number of zones in an area shall depend on its size and the strategies undertaken for its development.
#### 3.1.2.1 Fire Zone 1
The following occupancy groups shall comprise this zone:
Occupancy A : Residential
Occupancy B : Educational
Occupancy C : Institutional
Occupancy D : Health Care
Occupancy E : Assembly
Occupancy F1,F2,F3 : Business and Mercantile (Offices, small shops and markets, large shops and markets)
Occupancy H1 : Storage Buildings (Low fire risk storage)
Occupancy K : Miscellaneous Buildings
#### 3.1.2.2 Fire Zone 2
The following occupancy groups shall comprise this zone:
Occupancy F4, F5 : Business and Mercantile (Garages and petrol stations, essential services)
Occupancy G : Industrial Buildings
Occupancy H2 : Storage Buildings (Moderate fire risk storage)
#### 3.1.2.3 Fire Zone 3
The only occupancy falling in this zone shall be Occupancy J, Hazardous Buildings.
#### 3.1.2.4 Change in Fire Zone Boundaries
The demarcations of fire zones may be changed or new occupancies may be included in any fire zone through the same procedure as for promulgating new rules or ordinances or both.
#### 3.1.2.5 Buildings on Overlapping Fire Zones
Buildings falling on more than one fire zones shall be considered to be situated on the zone in which the major portion of the building falls. If a building is divided equally between more than one fire zone, it shall be considered as falling in the fire zone having more hazardous occupancy buildings.
#### 3.1.2.6 Restrictions on Temporary Constructions
Permission may be granted by the Authority for temporary constructions only in fire zones 1 and 2 and not in fire zone 3. Such temporary constructions shall adhere to the conditions of the permission and shall be demolished and removed completely after the expiry of the duration of the permission unless it is extended by the Authority or a new permission is obtained.
### 3.1.3 Permissible Types of Construction for Various Occupancies
#### 3.1.3.1 New Buildings
Types of constructions permitted for various buildings on the basis of fire zones are specified in Table 3.2.4.
#### 3.1.3.2 Existing Buildings
Existing buildings in any fire zone need not comply with the provision of this Code for type of construction unless they are altered or in the opinion of the Authority they constitute a hazard to the safety to the occupants of the buildings or the adjacent properties.
### 3.1.4 Exterior Walls
The fire resistance rating of the exterior walls shall conform with the provisions set forth in Table 3.2.2 and 3.2.3.
### 3.1.5 Mixed Occupancy Separation
When a building accommodates more than one occupancy, each such occupancy shall be separated from the others according to the provisions specified in Sec 2.3.
### 3.1.6 Basement Floor
Basement floor of a building shall be enclosed with a one hour fire resistive construction. Doors in such constructions shall be made of noncombustible materials.
Exception :
Occupancies F4 and K need not conform with these requirements.
### 3.1.7 Restricting Vertical Spread of Fire
#### 3.1.7.1 Interior Walls
Propagation of fire, smoke, gas or fume through the voids of fire resistive floors and walls shall be restricted by sealing such voids with an approved material which shall have a fire resistance rating of at least equal to that of the floor-wall assembly. The sealing material shall be capable of preventing passage of flame and hot gases sufficient to ignite cotton waste when tested in accordance with ASTM E119-8.
#### 3.1.7.2 Exterior Walls
Openings in the exterior wall in two consecutive floors lying within 1.5 m laterally shall be separated with a flame barrier projecting at least 75 cm from the external face of the exterior wall. The flame barrier shall have a fire resistance rating of not less than three-fourths hour.
### 3.1.8 Exceptions to Fire Resistance Requirements
The provisions of this section are exceptions to the occupation separation requirements of Table 3.2.1.
#### 3.1.8.1 Fixed Partitions
a) Stores and Offices : In such cases where offices, stores and similar places occupied by one tenant are separated by nonload bearing walls that do not form a corridor serving an occupant load, the partition walls may be constructed of any one of the following :
i) Noncombustible materials;
ii) Fire retardant treated wood;
iii) One hour fire resistive construction;
iv) Wood panels or similar light construction up to three fourths the height of the room in which placed; and
v) Wood panels or similar light construction more than three-fourths the height of the room in which placed with not less than upper one fourth of the partition constructed of glass.
b) Hotels and Apartments : In such cases where nonload bearing walls act as interior partitions in individual dwelling units in apartment houses and guest rooms or suites in hotels when such dwelling units, guest rooms or suites are separated from each other and from corridors by not less than one-hour fire-resistive construction, the partition walls may be constructed of any one of the following:
i) Noncombustible materials or fire retardant treated wood in buildings of any type of construction; or
ii) Combustible framing with noncombustible materials applied to the framing in buildings of Type 3 construction.
c) Folding, Portable or Movable Partitions : Folding, portable or movable partitions need not have a fire resistance rating if the following conditions are satisfied:
i) Required exits are not blocked without providing alternative conforming exits;
ii) Tracks, guides or other approved methods are used to restrict their locations; and
iii) Flammability shall be limited to materials having a flame-spread classification as set forth in Tables 3.3.2 and 3.3.3 for rooms or areas.
#### Table 3.3.2: Flame Spread Classification
| Class | Flame Spread Index |
| :---: | :----------------: |
| I | 0–25 |
| II | 26–75 |
| III | 76–200 |
#### Table 3.3.3: Maximum Flame Spread Class
| Occupancy Group | Enclosed Vertical Exit Ways | Other Exit Ways | Rooms or Areas |
| :-------------- | :-------------------------: | :-------------: | :-------------: |
| E | I | II | II |
| B | I | II | III |
| C, D | I | I | II |
| J | I | II | III |
| F, G, H | I | II | III |
| A2, A5 | I | II | III |
| A1, A3, A4 | III | III | III |
| K | No restrictions | No restrictions | No restrictions |
d) Walls Fronting on Streets or Yards : For walls fronting on a street or yard having a width of at least 12 m, certain elements of the wall may be constructed as follows regardless of their fire-resistive requirements:
i) Bulkheads below show windows, show window frames, aprons and show-cases may be of combustible materials provided the height of such construction does not exceed 5 m above grade.
ii) Wood veneer of boards not less than 25 mm in nominal thickness or exterior type panels not less than 10 mm in nominal thickness may be used in walls provided:
1. the veneer does not extend beyond 5 m above grade; and
2. the veneer is placed either directly against noncombustible surface or furred out from such surfaces not to exceed 40 mm with all concealed spaces fire blocked.
e) Trim: Wood may be used to construct trim, picture moulds, chair rails, baseboards, handrails and show window backing. If there is no requirement for using fire protected construction, unprotected wood doors and windows may be used.
f) Loading Platform : Noncombustible construction of heavy timber may be used for exterior loading platforms with wood floors not less than 50 mm in nominal thickness. Such wood construction shall not be carried through the exterior walls.
g) Insulating Boards : Combustible finished boards may be used under finished flooring.
### 3.1.9 Shaft Enclosures
#### 3.1.9.1 General
Construction requirement for shafts through floors shall conform to the provisions of Table 3.3.1.
#### 3.1.9.2 Extent of Enclosures
Shaft enclosures shall extend from the lowest floor opening through successive floor openings and shall be enclosed at the top and bottom.
Exceptions:
1. Shafts need not be enclosed at the top if it extends through or to the underside of the roof sheathing, deck or slab.
2. Noncombustible ducts carrying vapours, dusts or combustion products may penetrate the enclosure at the bottom.
3. Shafts need not be enclosed at the bottom when protected by fire dampers conforming to "Test Methods for Fire Dampers and Ceiling Dampers" (U.B.C. Standard No. 43-7), installed at the lowest floor level within the shaft enclosure.
#### 3.1.9.3 Special Provision
In groups other than Occupancies C and D, openings which penetrate only one floor and are not connected with any other floor or basement and which are not concealed within building construction assemblies need not be enclosed.
#### 3.1.9.4 Protection of Openings
Openings in shaft enclosures shall be protected with a self-closing or an automatic-closing fire assembly having a fire resistance rating of
i) one hour for one hour fire resistive walls
ii) one and one-half hours for two hour fire resistive walls
#### 3.1.9.5 Rubbish and Linen Chute Termination Rooms
Rubbish and linen chute shall terminate in rooms separate from the remaining of the building having the same fire resistance as required for shafts in Table 3.3.1 but not less than one hour.
### 3.1.10 Expansion and Contraction Joints
Expansion and contraction joints provided to accommodate expansion, contraction, wind or seismic movement shall be protected with an approved material having the same degree of fire resistance as that of the wall or floor in which it is installed.
### 3.1.11 Weather Protection
#### 3.1.11.1 Weather Resistive Barrier
All weather exposed surfaces shall have a weather barrier to protect the interior wall from damping. Such weather barriers shall have a fire resistance rating of at least equal to that of the wall or floor on which it is applied. Weather resistive barrier need not be used in the following cases:
i) When exterior covering is of approved waterproof panels
ii) In back plastered construction
iii) When there is no human occupancy
iv) Over water repellent panel sheathing
v) Under approved paper backed metal or wire fabric lath
vi) Behind lath and portland cement plaster applied to the underside of roof and eave projections.
#### 3.1.11.2 Flashing and Counter Flashing
Exterior openings exposed to the weather shall be flashed to make them weather proof. There shall be copings with all parapets. Corrosion resistant metals shall be used for flashing, counter flashing and coping.
#### 3.1.11.3 Waterproofing Weather-exposed Areas
Waterproofing shall be applied to exposed surfaces like balconies, external stairways and landings.
#### 3.1.11.4 Damp-proofing Foundation Walls
Outside of foundation walls enclosing a basement floor below finished grade shall be damp-proofed from outside.
### 3.1.12 Members Carrying Walls
All members carrying masonry or concrete walls shall be fire protected as specified in Table 3.3.1.
### 3.1.13 Parapets
Parapets constructed on exterior wall of a building shall have the same degree of fire resistance required for the wall upon which they are erected and there shall be noncombustible faces on the side adjacent to the roof surface for the uppermost 405 mm including counter flashing and coping materials. The height of the parapet shall be at least 750 mm from the upper surface of the roof.
### 3.1.14 Projections
Sunshades, cornices, projected balconies and overhangings beyond walls of Type 1 or 2 construction shall be of noncombustible materials. Projections from walls of Type 3 may be of combustible or noncombustible materials.
### 3.1.15 Guardrails and Barriers
#### 3.1.15.1 Guardrails
Guardrails shall be provided to protect unenclosed floor and roof openings, open and glazed sides of stairways, landings and ramps, balconies or porches, which are more than 750 mm above the grade or floor below, and roofs accessible for purposes other than service works.
#### 3.1.15.2 Barrier
Barriers shall be provided in parking garages located more than 1.5 m above the adjacent grades. The height of the barrier shall be at least 300 mm and it shall be centred at 450 mm above the parking surface.
### 3.1.16 Insulation
The provisions of this section are applicable to thermal and acoustical insulations located on or within floor-ceiling and roof ceiling assemblies, crawl spaces, walls, partitions and insulation on pipes and tubings.
Materials used for such insulation and covering shall have a flame spread rating not more than 25 and a smoke density not more than 450.
### 3.1.17 Atria
#### 3.1.17.1 General
Atria may be provided in all groups other than Occupancy J (Hazardous Buildings) provided there are sprinkler system installed throughout the building. Such atria shall have a minimum opening and are as specified in Table 3.3.4.
![Table 3.3.4: Atrium Opening and Area]()
#### 3.1.17.2 Smoke Control System
A mechanically operated air-handling system shall be installed to exhaust the smoke either entering or developed within the atrium.
a) Exhaust Openings : The location of the exhaust openings shall be in the ceiling or in a smoke trap area immediately adjacent to the ceiling of the atrium above the top of the highest portion of door openings into the atrium.
b) Supply Openings : Supply openings designed for a minimum of 50 per cent of the exhaust volume shall be located at the lowest level of the atrium. Supply air may be introduced by gravity provided the height of the atrium is not more than 18 m and smoke control is established. For atria having height greater than 18 m, supply air shall be introduced mechanically from the floor of the atrium and directed vertically toward the exhaust outlets. Supplemental air supply may be introduced at upper levels in atria over six storeys in height or when tenant spaces above the second storey are open to the atrium.
c) Automatic Operation : The smoke control system for the atrium shall be activated automatically by the automatic sprinkler system or smoke detectors installed within the atrium or areas open to the atrium.
d) Manual Operation : The smoke control system shall also be manually operable for use by the fire department. The smoke control system may be separate from or integrated with other air handling systems. Air handling systems interfering with the smoke control system shall be shut down automatically when the smoke control system is activated.
e) Smoke Detector Location : Smoke detectors which will automatically operate the smoke control system of the atrium shall be accessible for maintenance, testing and servicing. Their locations shall be as follows:
i) At the atrium ceiling, spaced in accordance with the manufacturer's instructions.
ii) On the underside of projections into the atrium, in accordance with the manufacturer's instructions.
iii) Around the perimeter of the atrium opening on all floors open to the atrium. These detectors shall be spaced no more than 9 m on centre and shall be located within 5 m of the atrium opening.
If projected beam type smoke detectors are used, they shall be installed in accordance with manufacturer's instructions.
f) Enclosure of Atria : Atria shall be separated from the adjacent spaces with fire resistive separation of at least one hour.
Fire windows may be provided in fixed glazed openings when the window has a fire resistive rating of at least three-fourths hour and the area of the opening does not exceed 25 per cent of the wall common to the atrium and the room into which the opening is provided.
### 3.1.18 Mezzanine Floors
Construction of a mezzanine floor shall conform with the requirements of the floor in which it is constructed but the fire resistance rating need not exceed one hour for unenclosed mezzanines.
## 3.2 REQUIREMENTS OF TYPE 1 FIRE RESISTIVE BUILDINGS
### 3.2.1 General
Type 1 construction shall be of materials like steel, iron, concrete or masonry. Walls and permanent partitions shall be of noncombustible fire resistive construction except that permanent nonbearing partitions of one hour or two hour fire resistive construction which are not part of a shaft enclosure, may have fire retardant treated wood within the assembly.
### 3.2.2 Exterior Wall
Exterior walls and all structural members shall conform to the requirements of Tables 3.2.2 and 3.3.1 for fire resistance rating. Openings in the exterior walls shall have a fire-resistive assembly of not less than three-fourths hour when they are located at not less than 6 m from an adjacent property line or centre line of a public way.
For occupancy groups B, C, D, E, F, G1 and H1 located less than 1.5 m from the property line and A and M located less than 1 m from the property line, no opening shall be permitted.
Exceptions:
i) Fire resistive protection need not be used for nonbearing walls of noncombustible construction fronting on public ways or yards having a width of at least 12 m.
ii) In all occupancy groups other than Occupancy H, exterior nonbearing walls may be of
1. one hour fire resistive noncombustible construction where openings are permitted, and
2. two hour fire resistive noncombustible construction where fire protection of openings is required.
### 3.2.3 Structural Frame
Structural frame shall be of reinforced concrete, masonry or steel as per the provisions of Part 6.
### 3.2.4 Floor Construction
Materials of floor construction shall be noncombustible and shall have fire resistance rating in accordance with Table 3.3.1.
### 3.2.5 Stairway Construction
Stairways shall be constructed with reinforced concrete, steel, masonry or any other hard noncombustible materials. For finishing works, brick, marble or other noncombustible materials may be used. Stairways shall be constructed in accordance with the exit provisions specified in Chapter 3, Part 4.
### 3.2.6 Roof Construction
Roofs and their members, other than the structural frame, may be constructed with unprotected noncombustible materials in all occupancy groups other than Occupancy J when every part of the roof framing including the structural frame is at least 8 m above the floor, balcony or gallery immediately below.
When every part of the structural framework of the roof of a building of Occupancy B or E or of an atrium is not less than 8 m above any floor, balcony or gallery, fire protection of all members of the roof construction, including those of the structural frame, may be omitted.
Where every part of the structural steel framework of the roof of a building Occupancy A or B is more than 6 m and less than 8 m above any floor, balcony or gallery, the roof construction shall be protected by a ceiling of not less than one hour fire resistive construction.
## 3.3 REQUIREMENTS FOR TYPE 2 FIRE-RESISTIVE BUILDINGS
### 3.3.1 General
Type 2 construction shall be of noncombustible materials like steel, iron, concrete, masonry or any other material permitted in this Code.
### 3.3.2 Exterior Walls and Openings
#### 3.3.2.1 Exterior Walls
Exterior walls shall be constructed of noncombustible materials and shall comply with the fire resistive requirements set forth in Tables 3.2.2 and 3.3.1.
Exceptions:
1. Nonbearing walls fronting on public ways or yards having a width of at least 13 m may be unprotected when entirely of noncombustible material.
2. In Occupancies other than C, D and J, exterior nonbearing walls may be noncombustible one hour fire resistive where unprotected openings are permitted and noncombustible two hour fire resistive where protection of openings is required.
3. In buildings of Occupancy A2, A5 and F, exterior noncombustible bearing walls may be two hour fire resistive where openings are permitted.
#### 3.3.2.2 Openings in Exterior Walls
Openings in exterior walls shall conform to the requirements of Table 3.2.3 and shall be protected by a fire assembly having a three-fourths hour fire resistive rating when they are less than 6 m from an adjacent property line or the centre line of a public way.
No openings shall be permitted in exterior walls of Occupancy B, C, D, E, F1, F2 and F4 less than 1.5 m from the property line, and no openings in Occupancy A, G1 and K less than 1 m from the property line.
### 3.3.3 Structural Frame
Structural frame shall be of reinforced concrete, masonry or steel as per the provisions of Part 6.
### 3.3.4 Floor Construction
Floors of construction Type 2 shall be of noncombustible materials permitted in this Code.
For wood flooring on masonry or concrete, the gap between the floor slab and the underside of the wood flooring shall be filled with noncombustible materials or fire blocked and there shall be no open spaces under the flooring exceeding 10 m2.
Exception :
Fire blocking need not be provided in floors at or below the grade levels.
### 3.3.5 Stairway Construction
#### 3.3.5.1
Stairways shall comply with the exit requirements of Chapter 3, Part 4.
#### 3.3.5.2
Interior stairways serving buildings not exceeding three storeys in height may be constructed of any material permitted by this Code. In buildings more than three storeys in height, interior stairways shall be constructed as required for Type 1 buildings.
#### 3.3.5.3
Exterior stairways shall be of noncombustible material except that on buildings not exceeding two storeys in height, they may be of wood of not less than 50 mm in nominal thickness.
### 3.3.6 Roof Construction
In all Occupancies other than F2, F4 and J, roofs and their members other than structural frame may be of unprotected noncombustible materials when every part of the roof framing, including the structural frame, is 8 m or more above the floor, balcony or gallery immediately below.
## 3.4 REQUIREMENTS FOR TYPE 3 FIRE RESISTIVE BUILDINGS
### 3.4.1 General
Structural and nonstructural elements of Type 3 construction may be any material permitted in this Code.
### 3.4.2 Exterior Wall
Exterior walls shall be constructed of in accordance with the provisions of Tables 3.2.2, 3.2.3 and 3.3.1. Openings in exterior walls shall be protected by a fire assembly having a fire resistance rating of at least three-fourths hour.
### 3.4.3 Structural Frame
Structural frame shall be of concrete, masonry or steel as specified in Chapter 2, Part 5.
### 3.4.4 Floor Construction
Floors shall have a fire resistance rating of one hour and shall comply with the requirements of Chapter 2, Part 5.
### 3.4.5 Stairway Construction
Interior stairway may be constructed of any materials permitted in this Code. Exterior walls shall be constructed of noncombustible materials or of wood not less than 50 mm in nominal thickness.
### 3.4.6 Roof Construction
Roof construction shall be of any materials permitted in this Code.
# Part III: General Building Requirements, Control and Regulation
Source: https://docs.sayed.app/bnbc2006/part-3-general-building-requirements-control-and-regulation/index
General building requirements and classification of buildings by occupancy and fire-resistance.
Part 3 sets out general requirements applicable to all buildings, and classifies buildings by occupancy group and by construction type based on fire resistance.
## Chapters
Site requirements, means of egress, light and ventilation, and other general provisions.
Occupancy groups and mixed-occupancy provisions.
Construction types and fire-resistance ratings.
## Appendices
Supporting appendices for Part 3.
# Appendices
Source: https://docs.sayed.app/bnbc2006/part-4-fire-protection/appendices
## APPENDIX A: Guidelines for Fire Drill and Evacuation Procedure for High Rise Buildings
## APPENDIX B: Fire Protection Considerations for Venting in Industrial and Storage Buildings
## APPENDIX C: Detailed Guidelines for Selection and Siting of Fire Detection System
## APPENDIX D: Special Requirements of Buildings more than 20 Metre High
***
## APPENDIX A Guidelines for Fire Drill and Evacuation Procedure for High Rise Buildings
### A1
### A2
### A3
### A31
### A32
### A33
### A4
### A4 l
### A42
### A43
### A44
### A45
Appendix A Guidelines for Fire Drill and Evacuation Procedure for High Rise Buildings
INTRODUCTION
The following guidelines are provided to enable safe evacuation of the occupants of a high rise building in case of fire or any other emergency.
FIRE REPORTING
Any occupant within the occupancy discovering a fire, heat or smoke, shall forthwith report the incident to the fire brigade directly or through the ground command station, if there be any. Reporting of emergency situation to fire brigade should not be unnecessarily delayed by any person by way of making, issuing, posting or maintaining any regulation or order, written or verbal, to that effect.
FIRE DRILLS
Fire drill shall be conducted quarterly (4 times a year) in existing buildings as detailed under the Fire Safety Plan (Sec A 4.7 and A 4.8 below) for the first two years from the data of enforcement of this Code. For new buildings, the period of 2 years shall be counted from the beginning of occupancy of the building. After this initial period of 2 years, fire drill shall be conducted twice a year in all buildings.
All occupants of the Paling. shall participate in the fire drill and the building service employees includin| fire warden and his/her staff shall actively help the inmates in the process ae drill. However, the very old, convalescent patients or otherwise incapacitated inmates are not obliged to actively take part in the exercise, except the fire warden and his staff and family members of such penn shall chalk out a clear plan as to how to evacuate in a real emergent situation with such incapacitated persons.
A may of such drills shall be kept in writing for at least 3 years for the inspection of fire brigade whenever ca or.
SIGNS AND FLOOR PLANS
A sign shall be cs and maintained in front of the landing area of lifts on all floors so conspicuously and in such size and colour (sign reference may be given) that occupants may not miss the same, which shall direct the occupants to use stairs and not Tits during emergencies /fires, if not directed otherwise and shall also contain a floor plan with exact location of the stair and the relative position between the sign and the stair. Such posting in front of the landing area of lifts shall be omitted only if such signs are posted on all floors and some other area conspicuously located with the same message inscribed on it.
The sign shall be written in Bangla, English translation of which reads "USE STAIRS IN CASE OF FIRE UNLESS OTHERWISE INSTRUCTED". The lettering shall be at least 25 mm in red on white background. the sign should be so written as to Laisa good legibility. When floor plan with stair location is shown, the si; shall be at least 250x300 mm. en two signs are used, one for the notice and the other for floor plan, the sizes shall at least be 60 x 300 mm and 200 x 300 mm respectively. The sign/signs may be posted directl above the call button of the lift or any other conspicuous location securely attached to the surface of the wall. The top of the sign shall not be more than 2 metres above floor level.
Signs Depicting Floor Number ;
A sign shall be posted and maintained on each stair enclosure preferably on the wall of the intermediate landing which in actual fact shall be half storey more or less than the actual indicating the floor number. The number shall be at least 75 mm square and in Bangla. The number and background shall be in contrasting colours, e.g. black on a white background.
Stair and Elevator Identification
Each stair and Elevator shall be identified by an alphabet in Bangla and posted with a sign and securely placed preferably on the wall of the stair side of the lift door from which a is to be made. The letters shall be 75 mm square and shall be painted on a contrasting background e.g. black on a white background.
Stair re-entry Provision
A sign shall be posted and maintained on each floor within stairway and on the occupancy side of the stairway where required, indicating whether re-entry is provided into the building and the floor where such re-entry is provided. The lettering and numbers of the signs shall be at least 25 mm high on a contrasting beckgeound: and shall be posted securely at least 1.5 m above the floor.
Command Station
Command station on the ground floor shall be provided with a detailed floor plan of the entire building including detailed locations of all first aid fire fighting equipment and other pertinent information. Command stations shall be adequately illuminated.
### A46 Two way Communications and Fire Alarm
A two way communication system between each floor and the command station on the lobby of the entrance floor shall be provided and maintained by the owner of the building. Similarly fire alarm on each floor and the command station shall be fitted and maintained.
A47 Fire Safety Plan . A fire safety plan shall be developed in line with the details elaborated under A 4.8 and must have the approval of the local Fire Department regarding its adequacy.
A 4.7.1 Once the bia is accorded after ele by the Fire Department, the plan shall be distributed to all the tenants of the building by the building management, (be it a committee or a cooperative) including the employees of the tenants and employees of the management.
A 4.7.2 If the building is owned by an individual or a single corporate body and the owner or right holding member/members of the corporate body are residing in the building, shall be equally subject to fire safety plan applicable to other tenants.
A4.7.3 All major changes in the safety plan shall be promptly reported to Fire Department for their approval.
### A48 Fire Safety Plan
Fire Safety Plan elaborates the purpose and objective of the plan with details of personnel and their duties and fire drilling and evacuation plan.
A 48.1 Fire Safety Plan starts with the location, address of the building with telephone number and details of any other communication facilities available within the building.
A48.2 Purpose of the plan is to delineate details of systematic safe and orderly evacuation of a part or whole of the building by its occupants in case of fire/emergency in the shortest possible time to a safe area through the safe means of egress. It also details out the use of in-built facilities of fire warning and fire fighting like fire alarm, first aid an etc. to safeguard the lives of the inmates of the building.
A4.8.3 Objective of the plan is to provide continued education to the inmates and the fire command personnel and keep the people oriented to the in-built equipment in readiness to act in the event of fire. The plan shall be rehearsed through fire drill and the written plans containing instruction shall be updated if needed and use of the in-built equipment along with initiating fire safety procedure to safeguard life in case of fire until the fire brigade arrives. ;
A484 Fire command crew may be cris Pe of personnel like Fire ia Director, Deputy Fire Safety Director, Fire Wardens and Deputy Fire Wardens. Number of these people shall be dependent on the size and number of inmates living within the building.
A 4.8.4.1 a) Fire Safety Director: The plan shall contain the name, whether employed by a fire security firm or directly employed by the management, assigned regular location, how to contact him at his/her regular location, how to contact him/her if not at regular location during normal working hours.
b) Qualifications and experience: Depending on the size and complexity of the building, the Director shall
be a person of proven capability, having good ra bay Soe schooling with adequate experience in dealing with fire. Preference may be given to retired Fire Department personnel.
c) Duties of Fire Safety Director shall primarily include but not be limited to the following.
i) Shall be well conversant with the written fire safety plan for the fire drill and evacuation
procedures. ;
ii) Shall be in charge of selecting qualified building service employees for the fire command and
. engage in organizing, training and supervising the works of command crew.
iii) Shall be responsible to conduct fire and evacuation drill.
iv) Shall be responsible for the availability and state of preparedness of fire command crew during
emergencies.
v) Shall be responsible for the assignment and training of Fire Warden on floor supported by
adequate number of Deputy Fire Wardens as detailed out in the fire safety plan.
vi) Shall be responsible for the day to day supervision of the warden and his deputies and the state
of alertness of the crew. When the number of crew of Warden and Deputy Wardens become such that it becomes impractical for the Director to check them directly during the working hours, the Warden or Deputy Warden shall intimate the Director for the persons not available for some length of time, so that he may provide substitute during such period of absence. Nonetheless the Director shall spot check any number of floors as he wishes or time permits. An up to date organization chart shall be displayed at appropriate locations.
vii) Cases of negligence to duties on the part of members of his crew shall be taken up by him and he
shall rectify the situation by appropriate measures as far as he has been empowered under the fire safety plan failing which he shall notify the matter to the owner or the management of the building. The owner or the management on their part shall take up the matter with the fire security firm or if employed directly shall deal with the matter directly. If the person/persons is/are employed by a firm, and the firm fails to correct the situation, the owner /management shall notify the matter to the Fire Department to take disciplinary action against the firm.
viii) In the event of fire/emergency he/she shall be in charge of fire command station and shall
supervise, guide and coordinate activities such as ensuring that the Fire Department has been notified of fire or fire alarm, direct the evacuation procedure as detailed in the fire safety plan, manning the fire command station, appraise the Fire Department about the spot of fire on their arrival, advise the Fire Department officer in charge of the operation.
A 4.8.4.2 a) Deputy Fire Safety Director: The fire safety plan shall contain the details of Deputy Fire Safety Director similar to the details mentioned under the Director A 4.8.4.1(a).
b) Qualification and experience shall also be similar to those of the Director excepting that he may be less experience than the Director and covered under A 4.8.4.1 (b).
c) Duties of the Deputy Fire safety Director shall be similar to those mentioned under A 4.8.4.1(c) except that he shall receive command from the Director for execution and shall assume the role of Director in his absence.
A 4.8.4.3 a) Fire Warden and Deputy Fire Wardens: The fire safety plan shall contain their names on the
organization chart for the floors they have been assigned against. The entire organization chart shall be kept updated in the command station for fire drill and evacuation assignment.
b) Tenant or tenants of each floor upon request by the owner or in-charge of the building shall assign and make available dependable and trustworthy person/persons under their employee at the disposal of the Director to act as Wardens, Deputy Wardens. They shall undergo basic fire fighting and evacuation training by the Director or his deputy.
c) Each floor of a building shall be under the command of a Fire Warden and each tenant under a Deputy Fire Warden for the safe evacuation of inmates in the case of fire. When the floor area of a tenant exceeds 700 m? a Deputy Fire Warden shall be assigned for each 700 m? or part thereof.
i) Each Fire Warden and Deputy Fire Warden shall be conversant with the fire safety plan. They
must be well acquainted with fire exits and location and operation of fire alarms.
ii) In case of fire or fire alarm, the Fire Warden and Deputies shall ascertain location of fire and
unfold evacuation procedure as directed from the command station and to the following general guides.
1. The most critical area for immediate evacuation would be the fire floor and the floors above.
Evacuation from other floors shall be initiated if so commanded by the ground command station or the situation indicates to be so. Evacuation should be carried out via stairs not influenced by fire and fire warden shall try to carry out the operation using stair other then the ones used by the Fire Department personnel. If this become impossible, the wardens before fame door to the fire floor shall sought advice from the Fire Department personnel.
2. Evacuation to two or more floors below the fire floor should be adequate. He/She shall continuously keep the ground command station informed of his/her location.
3. Ensure that fire alarm has been transmitted.
4. Fire Wardens and their deputies shall ensure that all the inmates are intimated of the excegency and shall immediately proceed with the evacuation exercise detailed under Fire Safety Plan.
5. Fire Warden shall keep the ground station informed of the step being taken by him/her.
6. Similarly Fire Warden above fire floor shall notify the command station of the means being taken by him/her or any other special feature after unfolding Fire Safety Plan.
7. If and when stairways serving fire floor/floors above become useless by the presence of fire, smoke, fumes, in several floors above and when fire engulfs a considerable number of inmates then use of elevators shall be considered in accordance with the followings:
* If the elevator serving the floor to be evacuated also serves the fire floor, the lifts shall
not be used. If there are more than one lift bank, however, the lift/lifts in the other bank may be used if notified by the ground command station that one may use such lift/lifts.
* If the lifts do not serve the fire floor or lift shaft has no opening on the fire floor, they
may be used if not otherwise instructed by the command station.
* Elevators taken over by trained in-house person or Fire Department personnel may be
used.
* In absence of unaffected available lift/lifts, Fire Warden shall decide to use the safest
stairway for evacuation based on considerations /information available on the floor and any other instruction received from ground command. Before entering the stairway with the evacuees, the Fire Warden shall be sure about the environment within the stairway by personal inspection and in case of adverse environment‘consider using an alternate stairway and shall notify the ground command accordingly.
* The Fire Warden shall keep the ground command informed of the means adopted by
him during the evacuation process.
A 4.8.4.4 a) Building Evacuation Supervisors: A Building Evacuation Supervisor shall be available at all times other
than normal working hours when the Fire Safety Director or his Deputy are not available within the building.
b) Building Evacuation Supervisor shall be a person capable of directing the evacuation procedure of
occupants within the buildings as detailed in the Fire Safety Plan.
c) During fire/emergencies, his primary function shall be to take over command of the ground station and
to direct and execute the evacuation process as laid down in the plan.
Building Evacuation Supervisor shall be trained by the Director and shall be under his command for all evacuation purposes. His activities shall be controlled and governed by the clauses in Fire Safety Plan and shall be subject to scrutiny of the Fire Department.
A 4.8.4.5 Fire Party: If, in the opinion of the Fire Safety Director and endorsed by the Fire Department that the
### A485
### A48.6
number of Wardens and Deputy Wardens are inadequate, a Fire Party shall be raised from among the employees of the tenants and the management who shall be acting as help to regular in-house fire fighting force in the event of fire and follow the same work schedule and fancbda in the same manner as Wardens/Deputy Warden.
Organization Chart for Fire Drill and Evacuation Assignment
a) An organization chart clearly yay tase et attributed to designated employees shall be
prepared as per Fire Safety Plan and posted to all tenants and in very conspicuous location/locations on each floor. A copy of the chart shall be in possession of the Fire Safety Director.
b) An updated list shall be continuously made available withthe Director, his Deputy and Fire Wardens
and their deputies for all the disabled occupants unable to move without aid in the stairs. Arrangement shall be made in detail in the Fire Safety Plan to have these inmates assigned in moving down the stairs two or more floors below fire floor. If it becomes ReCeerY to move them still further down the stair, help may be sought of the elevator bank unaffected by fire and evacuated safely to ground floor. In case any extra assistance is needed, the Director shall be notified.
c) During fire or fire drill exercise, Fire Wardens shall be using arm band or such other identification.
d) During fire on the fire floor it is to be ensured that all inmates are notified and are evacuated to safe
area. A rush search shall be carried out including lavatories that all the inmates have been covered arid the person in charge of this operation shall be trained in accomplishing this task fast and flawless.
e) Persons not available on duty as per organization chart shall be promptly replaced as per contingency
plan detailed in the Fire Safety Plan.
f) On completion of evacuation operation, a head count shall be carried out of all the regular occupants
known to have occupied the floor evacuated.
g) Immediately on receipt of the alarm, the Fire Wardens shall take position near the two way
communication station on the floor, so that he/she can maintain continuous contact with the ground command and receive instructions.
Instruction to Inmates of the Building: Once the Fire Safety Plan has been approved by the Fire Department, the applicable portion of the plan shall be distributed to all the tenants and the management of the buildin; who in turn shall pass it on the their respective employees. All the occupants shall actively participate an: cooperate in carrying out the provisions of Fire Safety Plan.
A 4.8.7 Fire Prevention and Protection Program: A Plan for periodic formal inspection of each floor shall be
### A48.8
### A48.9
developed in respect of exit facilities, fire pied nin and good house keeping. Reports of such inspection shall be carefully maintained for inspection of Fire Department. The Plan shalttiave provision for monthly testing of two way communication and fire alarm system.
Detailed Building Information: A form shall be maintained for the benefit of all concerned with fire hazard of the building and shall contain the following basic information.
a) Building address in adequate details about its location.
b) Name, Address and telephone number of the owner (corporate body or individual) and the person in
charge of the building.
c) Name address and telephone number if any, of the Fire Safety Director and his Deputy.
d) Certificate of occupancy.
e) Height, area, construction class (details of various load and non-load bearing elements).
f) Number, type and location of fire stairs and/or fire towers.
g) Number, type and location of horizontal exits or other refuge areas.
h) Number, type location and operation of elevators and escalators (if any).
i) Locations of fire alarm — floorwise and central.
j) Communication System (telephone, walkie talkie).
k) Size and location of stand pipe system, gravity or pressure tank, fire pump and the name and
qualifications of the person or persons in charge of the facilities.
1. Automatic fire sprinkler system, primary and secondary water supply system and the area or areas being protected along with the name and qualification of the person or persons in charge.
m) Any other fire extinguishing systera, their location, efficacy and other pertinent details.
n) Average number of employed persons by day and night.
0. Average number of disabled persons visiting the building by day and night.
p) Average number of outsiders visiting the building by day and night.
q) Locations, types and capacities of other service facilities like primary and standby electric power,
normal and emergency lighting arrangement, heating with fuel (if any), ventilation with fixed windows, other means of emergency exhaust facilities of smoke and heat, air-conditioning system including floor coverage and ducting, refuse disposal facilities, any other fire fighting equipment, any other service facilities available. :
r) Measures taken or to be taken for addition, alteration and repair of any aspect within the buildings.
s) Information on flammable solids, liquids and gases if used and stored within the building premises.
t) In mixed occupancy, complete details of such occupancies and their special needs to be covered during
fire or emergencies.
Floor plan of entire building with floors having different configuration showing locations of fire fighting facilities shall be kept under the command of Fire Safety Director with a copy to Fire Department.
A 4.8.10 In developing Fire Safety Plan, evaluation of all the individual floor layout, total occupancy load on each
floor, number and kinds of exits available, zoning of the floor by area and occupancy shall be taken into consideration, careful evaluation of occupant movements and the most expeditions routes to exit and alternate routes shall be identified and taken into consideration.
A 4.8.11 Personal Fire Instruction Card: All the occupants of the building shall be supplied with a personal Fire
Instruction Card containing details of the floor plan and exit routes as well as instruction to be followed during fire. Instructions may contain the following either in Bangla or both in Bangla and English.
### A4.8.11.1 English Text of Instruction
a) Safety First
b)
d)
* Push button fire alarm boxes (number is mentioned here) are provided on your floor. Please read
the operating instruction posted on them. - Please read the oes instructions on the body of the fire cal rovided in your floor.
* Nearest exit from your flat is shown in this plan (plan to be provided chy
* Assemble on the ground floor at the location indicated on the following plan. For clarification,
Sa the Warden or Deputy Warden. (plan of assembly point in poles floor to be provided ere)
For personal and collective safety, notify the Warden/Deputy Warden in case.
* Exit route and/or door are‘obstructed by dumping of boxes or such other loose materials.
* Staircase door, lift lobby doors do not close mgt ion or completely. ‘
* Push button fire alarm or fire extinguisher are obstructed or damaged or seem to be out of order.
If you Discover a Fire
* Break the glass and push the button of the nearest fire alarm and call the fire service.
* With assistance from the floor Warden if needed, fight fire with the in-built facilities on your floor.
* Evacuate, if so instructed by the Warden
When you hear Evacuation Instructions
Immediately leave the floor taking the nearest staircase.
Report to your Warden on reaching the predetermined assembly point outside the building. Try not to use lifts.
Avoid going to cloak room.
Refrain from running or shouting, do not get panicked.
Do not waste a moment collecting personal belongings.
Keep the lift lobby and staircase doors shut.
(oe eet ie ee
### A4.8.11.2 Bangla Text of Instruction
ক) সতর্কতাই সর্বোৎকৃষ্ট রক্ষা ব্যবস্থা খ) নিজের এবং সামগ্রিক নিরাপত্তার স্বার্থে... গ) আপনি যদি কোথাও আগুন দেখতে পান ঘ) স্থান ত্যাগের নির্দেশ পাওয়ার সাথে সাথে নিম্নলিখিত ব্যবস্থা গ্রহণ করবেন
## APPENDIX B Fire Protection Considerations for Venting in Industrial and Storage Buildings
### B1
### B11
### B12
### B2
### B21
### B2.1.1
### B2.1.2
### B2.1.3
### B2.1.4
### B2.1.5
### B2.1.6
### B2.1.7
### B2.1.8
### B2.1.9
### B2.1.10
### B2.1.11
Appendix B Fire Protection Considerations for Venting in Industrial and Storage Buildings
SCOPE
This appendix covers venting requirements in industrial buildings. Provisions contained herein shall be applicable to single storey factory and storage facilities requiring large floor areas without dividing walls and enclosures.
This annex does not cover fire and smoke venting requirements for tall buildings.
Venting requirements in industrial buildings are specified in this appendix under two heads as follows : a) Smoke and fire venting
b) Explosion venting
SMOKE AND FIRE VENTING The following provisions shall be complied with for fire and smoke venting.
The combustion product of fire including smoke, being lighter than surrounding air tend to accumulate near the high point of a structure and tend to spread out in all directions to form a floating layer on top of a relatively cool air below. In absence of vent, the hot floating layer progressively become pales and the whole occupancy is engulfed with smoking hot gases. Time needed to reach this stage may be only a few minutes depending on the type of materials on fire, storage conditions of the materials involved etc.
Convection current of air always help lateral spread of fire once the hot gases reach the roof.
Adequate number of vents, properly fre ee and judiciously placed, can disperse the smoke and hot gases to atmosphere, thereby prevents spread of fire, as well as reduces risk of explosion from unburnt gases.
Time needed for accumulation of hot gases and smoke within the structure being very short, it is imperative that the venting devices are to be so designed and installed that they operate automatically at the earliest sign of fire, sensed through smoke and heat detectors.
The smoke and fire venting system shall be so designed and installed as to keep the temperature of the combustion product as low as possible, preferably below 150°C.
Venting systems are complement any of the to fire extinguishing system. Where automatic sprinklers are installed as fire extinguishing system, the sprinklers shall operate before the vent system comes into operation.
It is obvious that the smoke venting is easier than cleaning smoke once the structure has been filled with it.
Apart from large area factory and storage, venting may be considered essential for windowless buildings, underground structures and hazardous occupancies. Automatic fire vents shall be provided in all industrial and storage buildings classified as medium hazard or above, with floor areas in excess of 750 m2, This provision is mandatory irrespective of whether a large area is compartmentalized or not.
Determination of precise venting requirements is difficult, as variables like rate of combustion vis-a-vis nature, shape, size and packaging of the combustible materials as well the size, height and disposition of the stacks of materials are involved with it.
Industrial buildings having floor area less than 750 m? and which is rated as low hazard industry, may use conventional ventilators fitted high above near the eaves of the external walls as vents for smoke and hot
ases, provided opening of the ventilators can be ensured at all times or are designed to open automatically in case of fire.
Because of the large volume of air present in the large industrial buildings, it is most unlikely that the closure of doors and windows shall eventually extinct the fire.
B 2.1.12 It is usually the vertical and not horizontal ventilation that is adopted in the single storey industrial
buildings.
B 2.1.13 Heat produced in fire being 70 to 80 per cent connective in nature, suitable arrangements shall be
### B2.1.14
incorporated in the vent system for early outflow of heat to atmosphere to contain fire spread.
To minimize venting problems use of combustible roof linings shall be avoided.
B 2.1.15 Wind produces a negative pressure when blowing across a flat roof or a roof with a pitch under 40°.
Negative pressure tend to draw gases out of the structure, thereby aids venting of hot gases and smoke.
### B2.1.16
To achieve full efficien
Conversely when the pitch is more than 40°, gases will be drawn inside and will oppose outward flow on the windward side of the roof.
cy in vents total area of cold air inlets into the buildings should be at least equal to total areas of all vents. Ideally the inlets should be as close to the ground as possible.
B 2.1.17 When vents are installed, the size, design, number and disposition and associated roof screen or curtain
boards shall be carefully assessed.
B2.2 Venting area i, oar ong for ventilation are estimated largely on the basis of assumed time needed between the build up of fire from the initial outbreak to the time of effective taking over by the fire brigade.
B 2.2.1 Because the entrained air forms the bulk of the vent gases, it is natural that the vent area required to be provided shall be proportional to the perimeter of the fire area. F
B 2.2.2 The effective area shall be the minimum cross-sectional area through which the hot gases must flow out to atmosphere.
B 2.2.3 Increased air movement generated by power operated fans shall be disregarded in deciding venting area because it is assumed that in the event of fire power will be disrupted and/or fan damaged.
B2.2.4 Effective vent opening shall be different for different occupancies but shall be proportional to the floor area. The ratios of total vent areas to be provided to the floor area are as shown below:
a) Low hazard industry 1:150
b) Moderate hazard industry 1:100
c) Hazardous occupancy 1:30 to 1:50
B2.3 Venting shall be accomplished by any of the types, such as monitors, continuous gravity type, unit type or sawtooth roof skylights.
B 2.3.1 Wire glass or metal panels shall be used in monitor type vents only if arrangements can be made for its automatic opening.
B 2.3.2 Use of plain thin glass shall be avoided because of its doubtful behaviour during fire. However, if glass or other early disintegrating suitable plastic materials are used, they should be designed for automatic operation.
B 2.3.3 In monitor or unit type vents, the panels shall be hinged at the bottom and bm era to open automatically. Both leaf of the vent shall be designed to vent simultaneously disregarding wind direction and ensure their effectiveness during fire.
B2.3.4 Moveable shutters in continuous gravity vents shall be designed to open automatically in case of fire.
B2.3.5 Unit type vents shall be relatively small ranging between 1 and 9 m?in area, have light weight metal frames and housed with hinged dampers. They shall be designed for both automatic and manual operation.
B2.3.6 Roof skylight shall be satisfactory for venting only if designed for automatic operation.
B 2.3.7. Exterior wall windows alone in industrial buildings shall not be accepted as satisfactory means of ventin; but may be reckoned as additional means of venting when located close to the eaves and are provided wit ordinary glass or movable section arranged for both manual and automatic operation.
B2.3.8 Because of substantial reduction in the effective venting area, baffles shall not be installed inside vents.
B2.4 Vents shall be automatic in operation unless where designed specifically for both manual and automatic operation.
B 2.4.1 The release mechanism shall be simple in operation and shall not be dependent on electric power for operation, as power operation may be disrupted during fire.
B 2.4.2 The automatic operation of vents can be achieved by actuation of fusible links or other heat or smoke detectors or by interlacing with the operation of sprinkler system or any other automatic fire eee system covering the area. The vents can be so designed as to open by counterweights utilizing the force o} gravity or spring loaded level following its release.
B2.4.3\_ For simultaneous operation automatic fire alarm and automatic vent system shall be coupled.
B2.4.4 Vents and automatic sprinklers where installed together, sprinkler shall go into operation first before vents open, in order to avoid delay in sprinkler irae Heat actuated devices, if used for vent release, shall be properly covered from water spray or sprinkler which might delay their action.
### B2.4.5
### B2.4.6
### B25
### B2.5.1
### B25.2
### B2.5.3
### B2.5.4
### B2.5.5
### B2.6
### B2.6.1
### B2.6.2
### B2.6.3
### B2.6.4
### B26.5
### B2.6.6
### B2.6.7
### B3
### B3.1
### B3.1.1
### B3.1.2
### B3.1.3
To ensure vent opening, release mechanism shall not only be joined to fusible links but also with smoke actuated automatic fire detectors, where the height of roof apex of the occupancy is 10 m or more or the materials handled or stored have high smoke producing characteristics.
Materials used in hinges, hatches and other related parts in vents shall be noncorrosive in nature for long trouble free operation.
Vents shall be properly sited, always as far as possible at the highest point in each area to be covered.
As far possible vents shall be sited right on top of the probable risk area to be protected to ensure free and speedy removal of smoke and other combustion product.
Minimum vent opening shall not be less than 1250 mm in any direction.
Vent spacing shall be designed considering the fact that higher number of smaller vents are better than smaller number of large vents.
Maximum spacing of vents shall be as follows:
a) Low hazard occupancy 45 m between centres
b) Moderate hazard occupancy 36 m between centres
c) Hazardous occupancy 22.5 to 30 m between centres
In deciding location of the vents on roof Sec B 2.1.15 shall be adhered to as far as possible.
Industrial buildings having large floor area without separating or subdivision walls shall be compartmentalized with the aid of roof screen or curtain boards. The curtains are extended from the roof downward at specific intervals preventing lateral spread of heat and smoke in the event of fire.
Curtain board materials shall be heavy sheet metal or any other noncombustible material capable of withstanding damage by heat or impact.
The curtain boards shall be reasonably gas-tight, although small openings for passage of pipes conduits etc. may be permitted.
They shall extend at least up to 2200 mm from the downside of roof. Sites of special hazard shall be enclosed by roof curtains extending down to 400 mm. They shall extend down to a height of 300 mm from the floor where the roof/ceiling exceeds 15m or more.
In moderate hazard occupancies the distance between the screens shall not exceed 75m and enclosed areas (compartmentalized) shall not exceed 4500 m?.
In high hazard occupancies the distance between the screen shall not exceed 30m and enclosed area shall be limited to 750 m?,
The enclosed roof area shall be so spaced and disposed as to create an effective area for disposing off smoke and hot gases of combustion.
In buildings provided with sprinklers, the screens shall preferably be so located as to coincide with unit areas of sprinkler system.
EXPLOSION RELIEF VENTS
Explosior. relief vents shall be provided in industrial premises where combustible dusts, flammable gases, vapours or mists in concentrations capable of initiating an explosion are present and constantly keep the premises under the threat of explosion hazards. Magnitude of pressure developed may range around 7x10° N/m? and ordinar ee will not be able to withstand shock that will be produced from such explosion. Such buildings shall be fitted with explosion relief vents to prevent structural damage.
Most ordinary buildings will not be able to stand under a sustained internal pressure of 7x10° N/m?. Consequently the vents shall be so designed as to operate at a pressure much below the pressure at which the walls shall crumble down.
Pressures rises with an explosion within an enclosure, even when vents are open and unobstructed. As a result any delay in opening venting devices further increase the pressure.
It is possible to isolate hazardous operations and equipment outside of buildings with a pressure resisting wall which will reduce risk of structural damage. Such operations and equipment may be housed in a single storey building having appropriate venting facilities and a device to absorb explosion shock from blowing through the duct back to the building.
B 3.1.4 Sometimes it may not be possible to house hazardous operations and equipment outside of the building, in which case the separation from other parts and equipment shall be achieved by pressure resisting walls and such units shall be ventilated outdoors. If suitable vents are integrated, external walls may be of heavy construction or of heavy panel which may be blown off easily.
B 3.1.5 No hazardous equipment or operations shall be permitted to be located in the basement or partially underground structure.
B3.1.6 Explosion hazards usually are accompanied by fire. Fixed fire fighting equipment like automatic sprinklers, if installed, shall be such that minimum damage is caused to it.
B 3.1.7 Maximum pressure in a vent structure decreases with increase in the size of vent but is independent of rupture pressure of the diaphragm. ’
B 3.1.8 Unobstructed vent opening is the most effective pressure release vent structures.
B3.1.9 Pressure required to rupture diaphragms of the vent areas and material varies directly with the thickness of the material.
B3.1.10 The extent of venting required directly varies with the degree of explosion hazard.
B 3.1.11 It has been established from experience that explosion from dusts, vapours and gases do not involve the entire column of the enclosures, rather concentrates in the upper and lower part of the explosion range. As a result such explosions are relatively weak compared to an optimum situation where the concentration of such matters spread all over the explosion range.
B3.1.12 Unrestricted rectangular vents are equally effective as square vents of the same area.
B3.1.13 The finer the dust particle size the more violent is the explosion for a given material. Due to very fast rise in ressure it is difficult to effectively vent such materials as aluminium powdes, hydrogen and acetylene. Flow burning dust in confined space may cause much damage because of longer duration of pressure. Some
dusts may even react with some inert gases such as nitrogen and carbon dioxide and ignite.
B3.2 Explosion relief vents may be provided with open or unobstructed vents, louvers, open roof vents, hanger e doors, building doors, windows, roof or wall panels or marble/fixed sash. Any or more than one of ese may be adopted depending on individual situations and requirements as decided by the Authority.
B 3.2.1 Suction of external wind pressure shall be taken into consideration while designing and type of vents since wind pressure may reach up to 2 x 10° N/m? in severe wind storms.
B 3.2.2 Selection of explosion relief vent for any occupancy shall be based on two considerations, safety to lives of inmates and minimum damage to property.
B3.2.3. When large hanger type doors or metal curtain doors in sidewalls are used as vents it has to be ensured that they are open during operation of the related machinery or equipment.
B3.2.4 Roof vents covered with weather hoods shall be as light as possible and attached lightly, so that it is easily blown off as and when an explosion occurs.
B3.2.5 Doors and windows used as ee tanec vents shall be so fixed as to open outward. Doors shall be fitted with friction, spring or magnetic, latches that function automatically at the slight increase in internal pressure.
B 3.2.6 Placed at the top or bottom, the hinged or projected movable sash shall be ng peeoon with latch or friction device to prevent accidental opening due to wind action or intrusion. Such latches or locks shall be well maintained.
B 3.2.7 Fixed sash shall be set with light anchorage in the wall or when the anchorage is tight shall be fitted with plastic glazing in plastic putty.
\| B 3.2.8 In worst scenario or case where a whole building or an entire room is involved, it may be desirable to have the entire structure constructed with light wall and roof to collapse and thus prevent the worst effect of explosion.
B3.4 Area requirement depend ordinarily on the expected maximum intensity or an explosion, the strength of the structure, the type of vent closure and other factors.
B 3.4.1 Venting shall be so planned as to prevent injury to inmates and damage to enclosure. In populated locations, substantial ducts or diverts shall be provided to channelize the blast towards a pre-determined direction.
B 3.4.2 When ducts are used, they shall be of such strength as to withstand the maximum expected explosion pressure.
### B3.4.3
### B3.4.4
### B3.4.5
### B3.4.6
### B3.4.7
### B3.4.8
### B3.4.9
### B3.4.10
### B3.4.11
### B3.4.12
### B3.4.13
### B3.4.14
### B3.4.15
### B3.4.16
If explosion are probable within the duct, they shall be equipped with diaphragm to rupture at predetermined locations. The duct system shall not be physically connected to more than one collector.
In large structures the location of vents shall be relative to the point of explosion as it may be very difficult to pinpoint location of explosion.
Light, hinged scrounge type panels shall be preferred over diaphragm type in slow explosion involving coal dust, chlorinated solvents etc.
Particularly in case of rapid explosion hazard, vent blocking or obstruction shall be meticulously avoided. Counter weights inducing inertia to vents shall be avoided.
Venting devices actuated by detonators shall open at as low pressure as possible and shall be of light construction, so that full opening can be quickly achieved.
Vents shall be so sized and designed as to prevent rupture of the protected device.
Skylight with moveable sash that opens outward or fixed sash having panes of glass or plastic that blow out readily under pressure from within can be used to supplement wall vents or windows, provided their resistance to opening or displacement may be kept as low as possible consistent with structural requirement of the building. :
Flexible plastic sheets in slotted frames may be used for vent closure in such manner as to budge and be relieved off the frame when subject pressure from within.
This transparent or translucent plastic sheets that crack or rupture under less pressure than single strength glass are preferred materials for vent closure or window sash.
For equivalent explosion pressure release, larger closed vents will be required compared to open vents.
More generous venting shall be provided for small enclosures like that of a machine or equipment room based on the following considerations:
\| Vent opening per unit Volume of enclosure | Types of volumes of enclosures | Examples | Remarks | | :--- | :--- | :--- | :--- | | **a)** \text^2 / 0.3\text0.9\text^3$ | Small enclosures of less than \text{ m}^3$ | Machines and ovens of light construction | | | **b)** \text^2 / 0.9\text^3$ | Small enclosures | More sturdy construction having reasonably high bursting pressure | | | **c)** \text{ m}^2 / 0.9\text{ to }1.5\text{ m}^3$ *(typo in original print for $\text{cm}^2$)* | Fairly large enclosure \text700\text^3$ | Bins, Silos, Rooms, Storage tanks | Important to try and predict point of origin of explosion in relation to vent location. | | **d) i)** \text{ cm}^2 / 2.25\text{ m}^3$
**ii)** \text^2 / 1.65\text2.25\text^3$
**iii)** \text{ cm}^2 / 1.5\text{ to }1.65\text{ m}^3$ | Large rooms or buildings over \text^3\$
- Enclosure with heavy reinforced concrete walls
- Light reinforced concrete brick or wood construction
- Light weight construction, prefabricated panels | Small fraction of space of the large enclosure occupied by hazardous equipment/machinery | |
### B3.4.15
### B3.4.16
If explosion are probable within the duct, they shall be equipped with diaphragm to rupture at predetermined locations. The duct system shall not be physically connected to more than one collector.
In large structures the location of vents shall be relative to the point of explosion as it may be very difficult to pinpoint location of explosion.
Light, hinged scrounge type panels shall be preferred over diaphragm type in slow explosion involving coal dust, chlorinated solvents etc.
Particularly in case of rapid explosion hazard, vent blocking or obstruction shall be meticulously avoided. Counter weights inducing inertia to vents shall be avoided.
Venting devices actuated by detonators shall open at as low pressure as possible and shall be of light construction, so that full opening can be quickly achieved.
Vents shall be so sized and designed as to prevent rupture of the protected device.
Skylight with moveable sash that opens outward or fixed sash having panes of glass or plastic that blow out readily under pressure from within can be used to supplement wall vents or windows, provided their resistance to opening or displacement may be kept as low as possible consistent with structural requirement of the building. :
Flexible plastic sheets in slotted frames may be used for vent closure in such manner as to budge and be relieved off the frame when subject pressure from within.
This transparent or translucent plastic sheets that crack or rupture under less pressure than single strength glass are preferred materials for vent closure or window sash.
For equivalent explosion pressure release, larger closed vents will be required compared to open vents.
More generous venting shall be provided for small enclosures like that of a machine or equipment room based on the following considerations:
Volume of enclosure enclosures. a) 100.cm\*/0.3 to 0.9m mall enclosures of less achines and ovens 0
than 30m? light construction b) 100 cm\*/0.9m mall enclosures More sturdy construc-
tion having reasonably high bursting pressure ly Bi = R
¢) 100m\*/0.9 to 1.5m: Bins, ilos, ooms | Important to try d) i)
Remarks
Storage tanks and predict point of origin of explo- sion in relation to vent location.
‘action of space o: the large enclosure occupied by hazardous equipment/machinery
i) 100cm\*/2.25 m
over 700m? Enclosure with heavy reinforce concrete, walls
Light reinforced concrete brick or wood construction Light weight construction,
pre fabricated panels
ii) 1000 cm2/1.65 to
2.25 m3
iii) 1000 cm\*/1.5 to
1.65 m3
As far as possible hazardous areas shall be segregated be means of fire walls or party walls to prevent spread of fire.
Use of tile or such other light construction materials shall not be permitted in hazardous locations because of its potential to cause injuries to inmates in case of explosion.
## APPENDIX C Detailed Guidelines for Selection and Siting of Fire Detection System
### C1 GENERAL
This appendix provides a guideline for selection and siting of equipment for fire detection in buildings. Ley! CHOICE OF FIRE DETECTORS
Fire detectors may respond to any one manifestations of combustions such as heat generation, smoke and flames. No single detector is able to meet the need of all types of fires and all t of occupancies. As such, based on needs arising out of various situations and occupancies, judicious selection is extremely important for the reduction of fire hazards. :
### C21 Heat Detectors
"Point" or "Spot" type detectors are actuated by heat at layer adjacent to it over a limited area. "Line" type detectors are sensitive to the effect produced by heated gas along any portion of the detector line. Both the types operate on two broad principles: one, the heat sensitive elements is actuated by temperature risin beyond a predetermined level; while the second system is actuated by predetermined rate of rise o} temperature.
### C22 . Smoke Detectors y
Three types of smoke detectors are commonly used. First type is actuated by absorption or scattering of visible or near-visible light by combustion product and known as “optical detector’. The second type is actuated by the production on ionization current within the detector and referred to as "ionization detector". The third type is sensitive to carbon monoxide or other products of combustion and is known as "chemically sensitive detector".
### C23 Flame Detectors
Flame detectors are sensitive to radiation emitted by flames.
### C3 APPLICATION
Since both heat, smoke and flame are produced during a fire, detectors responding to all these are accepted as general purpose detectors.
C31 Fixed temperature heat detectors are suitable for use where ambient temperatures are high and or may rise and fall rapidly over a short period.
### C3.2 Rate of Rise Heat Detectors
These are suitable for use where ambient temperatures are low and/or may rise over a wide range slowly. Abnormally sharp rise in temperature during a fire actuates this alarm. ts such it cannot be used with confidence where ambient temperatures reaches in the neighborhood of 40°C, but are best used where ambient temperatures are in the range of about 40°C.
### C33 Smoke Detectors
In general, these should be used at places where ambient temperature varies between 0° to 35°C.
### C3.4 Optical Smoke Detectors
Invisible smoke from a clear burning shall not actuate the such detectors. But they respond quickly where smoke is optically dense and as such suitable for use in dust free clean atmosphere. Over a period of time, due to dust and dirt, the sensitive surface of photo sensitive element and Dor executor aap of optical detectors may loose its efficiency and as such optical detectors should be cleaned and maintaine pels a
### C3.5 Ionization Chamber Smoke Detector
These respond: quickly to invisible smoke of clear burning, but may not respond to fire producing dense smoke. These can be used in dust free, humidity controlled area. Smoke and other fumes, dust including slow accumulated and disturbed aerial dust, fibre, steam and condensation produced by normal processes and vehicle engines may, cause false alarm. Warehouses exposed to fast air flows can also cause false alarm. Burning of polyvinyl chloride will not sensitize the detector in time and may provide late warning or no warning at all.
### C3.6 Chemically Sensitive Smoke Detectors
Chemically coated sensitive elements react to carbon monoxide or other products of combustion present in smoke. Dust or moisture adversely affects the sensitive elements and are not very suitable for residential | use.
C3.7 Smoke detectors are not naturally suitable in places where the production process produces smokes. Other suitable types need to be used.
### C3.8
### C4
### C41
### C42
### C43
### C44
### C45
### C46
### C47
cs
### C6
### C61
### C62
### C63
### C64
### C65
### C66
### C67
### C68
Application of flame detectors are restricted due to the fact that all combustions do not necessarily accompany flame and that clear line of sight is desirable as radiation from flames travel in straight lines for actuation of sensitive element. As supplement to heat and smoke detectors, flame detectors may be used.
SITING OF DETECTORS
Every portion of building should be covered and all effectively enclosed spaces should be considered separately based on the limits of spacing for types of detectors concerned.
Rooms divided into sections by walls, partitions or storage racks, as in libraries and archives, arching up to 300 mm to the ceiling or goods stacked in defined areas shall have detectors for each section of passageway.
Hoist, elevators and similar openings, windows, doors, ventilators and inlet ducts of an air-conditioning system shall be covered by detector within 1.5 m at the top for every 2 m of their width or part thereof.
Detectors shall be installed at the centre of each inlet to the return duct of an air-conditioning system. Detectors shall be installed 2 m apart if the inlet is continuous or oblong.
Staircases shall be covered by detectors on each floor, and all lantern lights shall be covered by detectors.
Specie of detectors shall be reduced up to 75 per cent from the standard spacing in case of ceilings with waffle having depth between 200 and 500 mm and up to 50 per cent with depths above 500 mm. Where detectors are installed in the ridges of the waffle, each waffle shall be treated as an independent compartment.
Ceiling intersected by beams more than 250 mm in depth, each | shall be considered as separate compartment and detectors shall be installed considering each bay an independent compartment.
HEIGHT CONSIDERATION
Coverage provided by the sensitive detectors fall sharply as the height above floor level increases, generally, where roof height exceeds 9 m, heat sensitive detectors become ineffective.
SITING OF THE SENSITIVE DETECTORS (POINT OR SPOT TYPE)
Distance from Ceiling When positioned, heat sensitive elements shall be placed between 25 and 150 mm from the ceiling or underside of roof.
Spacing of Detectors Depends on probable hazards in relation to occupancy and shall have to be approved by the fire authority.
When ceiling are crossed by beams, girders or other structural elements of 250 mm or more in depth to form compartments, detectors shall be placed in each compartment.
Single Truss and North Light Roofs
One row of detectors shall be sited along the apex of each roof or bay. Space of this row of detectors and other detectors headed to cover the area shall be determined from the designed requirement and approved by the authority.
Floor Opening At least one detector shall be suitably positioned within 1.5 m of hoists, elevators, stairways, wall holes and similar openings to the floor above.
Lantern Lights Fixed temperature type detectors shall be used in lantern which shall be protected from direct sun light as the combination of solar and internal heating cause rapid temperature variation.
Heated Areas within Building
Only fixed temperature type detectors shall be used in areas like kitchen, boiler room, furnace, room etc. where sudden temperature rise may take place. If ambient temperature is likely to exceed 40°C, detector's nominal operating temperature may need to be increased. However the maximum operating temperature setting should not exceed 117°C.
Vibration and Rapid Temperature Change Detectors covering hoist apertures may be subject to vibration and may experience rapid temperature change and thus shall be fitted with fixed temperature fusible alloy fuses. ‘
### C8 SITING OF SMOKE SENSITIVE DETECTORS
**C8.1** Once on fire, a building accumulates the greatest concentration of visible and invisible smoke at the highest points of enclosed areas. Smoke detectors are usually sited here. The detectors shall be as mounted as to place the sensing elements between 25 and 100 mm from the underside of roof.
**C8.2** Area coverage by individual detectors are same as that of heat detectors but the maximum distance between two detectors may be 20 per cent more than that recommended for heat detectors. Actual spacing depends on airflow pattern in protected area.
**C8.3** Area coverage of smoke detectors is dependent on many factors. The following aspects shall be taken into considerations in the design of detectors.
a) When a big room or space to be protected is divided into section by walls, partition or storage racks including book stacks in libraries and archives, each section or passageway shall be protected separately. Additional rows of detectors shall be provided at the rate of one per 2 metre or part thereof. The detectors being not more than 3m apart in each row, shall be staggered.
b) Any area of a building provided with mechanical ventilation system results in more than 10 air changes per hours, which causes dilution of smoke and a definite air flow pattern is established. In such cases ventilation inlet and exhaust openings shall be covered by additional detectors.
c) Additional detectors may become necessary to cover smaller extract ducts, windows, ventilations and other openings. In rooms with high rate of air change, additional detectors may be necessary to cope with air flow pattern and dilution of combustion product.
d) Detectors shall be installed within 1.5 m of duct to monitor inlet duct.
e) Detector shall be installed in the centre of inlet of return air duct. Where place above the false ceiling is used as return air duct, the opening to return air shall have a detector every 2 m or part thereof of its length within 250 mm of the opening.
f) In most buildings mechanical ventilation do not run continuously. The detectors shall, thus, be so sited as to detect fire irrespective of mechanical ventilators are in operation or not.
g) Warm air naturally concentrates under ceiling and in the apex of pitched roofs. Sometimes this warm air creates what is known as heat barrier acting as an effective barrier to the products of combustion. This results in small fire producing little or no appreciable change in ambulant environment. The combustion products from such a fire will spread out below the heat barrier in the same way as they do beneath the ceiling or an apex of a pitched roof. Siting of detectors should be arranged to take this into account.
h) Factors capable of establishing temporary or permanent effects on detector's siting shall be borne in mind while designing the system and include the following:
i) Various forms of overhead heating
ii) Exhaust air from air cooling equipment blowing out into the room or factory area
iii) Deep beams
iv) Roofs and ceiling of unusual shape
v) Building with ground areas above 10 m and up to 30 m in height
vi) Staircases
vii) Canteen and Restaurants
viii) Plant Rooms
ix) Ambulant air currents
## Appendix D Special Requirements of Buildings more than 20 Metre High
### D1 GENERAL
This appendix specifies the special requirements for the fire protection in buildings more than 20 m in height.
### D2 CONSTRUCTION
**D2.1** Construction of all load bearing components like stairways, corridors and facades shall be of noncombustible materials.
**D2.2** Internal staircase walls shall be made of bricks or reinforced concrete with a minimum of 2 hour fire rating.
**D2.3** The crown and landings of a staircase shall be ventilated to atmosphere with 0.5 m² openings in the external walls and crown. Because of difficult location or other compelling reasons, if it becomes impossible to ventilate the staircase, a positive pressure of 50 pa shall be maintained inside the staircase by any mechanical means. Pressure sensitive Automatic Fire Alarm System shall be installed in the staircase. Stair roof shall be 1 m above the surrounding roof level. Use of glazing or fire bricks in the stair shall not be permitted.
**D2.4** Materials used for inner finish shall be restricted to Class I rating of flame spreadability.
### D3 LIFTS
Lifts installed in tall buildings shall comply with the following requirements over and above those listed under Chapter 5, Part 8.
**D3.1** Walls enclosing the lift core shall have a fire resistance rating of 2 hours. Lift shaft shall have a top vent area of not less than 0.2 m².
**D3.2** The room containing the motor operating the lift shall preferably be placed at the roof of the lift core and shall be separated from the rest of the lift core by a floor wall having same fire rating as that of the lift core walls.
**D3.3** Landing doors in lift core shall have at least half an hour fire resistance rating.
**D3.4** Not more than 4 independent lifts can be assembled together in one liftbank core and the core walls of individual lifts shall have a fire resistance rating of at least 2 hour.
**D3.5** Lift car doors shall have a fire resistance rating of at least 1 hour.
**D3.6** For lift in tall buildings above 20 m in height, collapsible gates shall not be permitted. Instead solid doors of fire resistance rating equal to that of Sec K 3.5 shall be installed.
**D3.7** When lifts are located in a central core location of building, exits from lift lobby shall be through a self closing smoke door of half an hour fire resistance.
**D3.8** Lifts shall not normally serve the basement.
**D3.9** Ground switch of the lifts hall be provided at ground floor level so that fire personnel can bring the lifts to ground level at the time of emergency.
**D3.10** Telephone or other voice communications facilities may be provided in lifts installed in buildings of 26m or more in height. The communication system, in such cases shall be connected to ground command station.
**D3.11** Appropriate slope in floor shall be provided to avoid water entering the lift shaft during fire fighting.
**D3.12** Suitable signs shall be erected and maintained at appropriate positions on all floors of a highrise building showing the floor plan and exit stairways. Cautions regarding use of lifts during a fire shall be inscribed in the signs.
### D4 FIRE LIFTS
One or more lifts shall be exclusively designed and maintained for the use of firemen is case of emergency.
**D4.1** The lifts shall be so designed and maintained as to be able to reach upper floors and are directly accessible to every dwelling or lettable floor space on each floor by fire personnel.
**D4.2** The lift or lifts shall have a load carrying capacity of 545 kg (8 persons) with a minimum floor area of 1.4 m² and auto close doors.
**D4.3** Power supply of the fire lift shall be separated from the main source supplying the building.
**D4.4** In case of power failure from normal supply, it shall be so designed as to trip automatically to alternate supply of power. In tall apartment complexes such tripover could be accomplished by manually operated changeover switch. Other alternative could be an electric wiring which shall be so designed as to bring the lift car to ground level with door open in case of power failure.
**D4.5** Fire lifts shall be operated on a two-button switch system. Two button switch is placed adjacent to the lift at floor level and kept in a glass covered box. When the switch is on landing call points become inoperative and the lift is controlled from the car. When the switch is off the lift returns automatically to normal operation and can be used by occupants at normal times.
**D4.6** On landing doors at each floor, the sign "FIRE LIFT" shall be painted conspicuously in such sizes as to be easily noticeable by occupants or users of the lift.
**D4.7** Irrespective of height lift speed shall be such as to reach the top floor from ground level in 1 minute.
### D5 SERVICE DUCTS
If there is any service duct, they shall comply with the following provisions.
**D5.1** Services ducts, if any, shall be enclosed by a 2 hour rated fire walls and doors. Ducts having area more than 1 m² shall be closed at each floor level except the passage of pipes etc. across the floors. The passage gaps of pipes, cables etc. shall be suitably sealed.
**D5.2** A vent opening at the crown of the service shaft shall be provided with an opening, the size of which shall be between 25 and 50 per cent of the duct area.
**D5.3** Air-conditioning or other service shafts shall be located as far away as possible from the exits of a building.
### D6 REFUSE CHUTES
Refuse chutes shall be enclosed by wall of fire resistance rating of at least 2 hours and shall extend at least 1 m above roof level and shall be vented to atmosphere. Chutes in no case shall be located within the staircase enclosure. Inspection panels and doors to refuse chutes shall be at least 1 hours fire resistance rating.
### D7 REFUSE AREA
Except multi-family dwelling, all other buildings shall incorporate provision of refuge area on the external walls as cantilever projection or any other suitable manner. Refuge area shall not be less than 15 m² at the heights mentioned below:
a) Floors between 20 and 26m: One refuge area on the floor immediately above 20 m.
b) Floors above 26 m: One refuge area on the floor immediately above 26 m and then one refuge area per five floor above 26 m.
### D8 BASEMENTS
Each basement shall be independently ventilated. Venting shall be achieved by grills, breakable stall board lights or pavement lights or by way of shafts of aggregates having cross-sectional area of not less than 2.5 per cent of floor area spread evenly around the perimeter of the basement. Alternatively air flow inlet at floor level and smoke outlet at ceiling level may be provided. Inlets and extracts may be terminated at ground level with stall boards and pavement light, but ducts for conveyance of fresh air to floor shall have to be laid. Stall boards and pavement lights shall be so positioned as to be easily accessible by fire brigade personnel.
**D8.1** Basement staircase shall be encased and placed near the outer edge of the basement with materials of 2 hours fire resistance. The stair shall be entered at the ground level from open air so that the smoke from a fire in the basement shall not obstruct any exit serving the ground and upper floors. Communication with the basement in case of emergency shall be maintained through a lobby provided with a fire resisting self closing door of 1 hour fire resistance. Additional staircases shall be provided at appropriate locations if travel distance exceeds 20 m.
**D8.2** Single intake duct may serve all the floors of a multi-storey basement, but separate smoke outlet duct or ducts shall be provided for each basement or basement compartment.
**D8.3** For lower basement floors, mechanical extractors for smoke venting shall be provided. The system shall operate automatically by heat sensitive elements or sprinklers. Devices with manual operation may also be installed. The following features shall also be considered.
a) Ventilating ducts shall be constructed with the brick masonry or cement concrete work as far as possible. Fire dampers shall be provided when these ducts cross the transformer or electrical switch board areas.
b) Kitchen using gas, departmental stores and shops shall not be allowed to operate in basement or sub-basement.
c) Openable windows on external walls shall be fitted with such locks which can be opened by fire man axe.
d) Floor area exceeding 750 m² shall be compartmented by fire partition walls having 2 hours fire rating. Floor areas provided with sprinklers may be increased by 50 per cent. In long buildings distance between fire walls shall not exceed 40 m.
### D9 BUILDING SERVICES
Building services in tall buildings shall comply with the following provisions.
**D9.1** Air-conditioning shall conform to the following:
a) Escape passageways like staircases, common corridors, lift lobbies shall not be used as return air passage.
b) Gauge metal of thickness and quality approved by the authority shall only be used in ducting.
c) Openings exerted by the passage of ducts across fire walls or floors shall be properly sealed with fire resisting materials like vermiculite concrete or asbestos fibre materials.
d) Duct insulation (inside and outside) materials shall be of noncombustible nature (such as glasswool) which shall not be wrapped or secured around the duct by any material of combustible nature.
e) Metallic ducts shall be used as far as possible instead of using the space above false ceiling as return air passage.
f) Floor areas more than 750m² shall be partitioned for isolation by fire walls and automatic fire dampers.
g) Air ducts serving main floor areas and corridors shall not pass through the staircase enclosure.
h) Air handling units and ducts shall be independent for each floor and there shall be no interconnection of ducts between floors.
i) In case of air handling units serving more than one floor, the system shall comply with the following provisions, in addition to the conditions mentioned above.
1. Individual floors shall be isolated from the main riser by incorporating automatic fire dampers working on fusible link.
2. Respective air handling units of air-conditioning system shall automatically be switched off as soon as the automatic fire alarm become active.
j) Treated fresh air conveyance through the vertical shaft shall be of masonry construction.
k) Ceiling and its fixtures shall be of noncombustible materials when these will be used as return air passage.
l) The air filters of the air handling units shall be of noncombustible materials.
m) Air handling equipment room shall not store any combustible material.
n) To have access to main fire dampers and for cleaning the duct of accumulated dusts, the main air duct trunk shall be fitted with appropriate inspection panels of tight fitting nature.
**D9.2 Fire Dampers**
Fire dampers shall be located in the line of air-condition ducts and return air ducts or passage in the following places:
* At the fire separation wall,
* Where ducts or passages entre the central vertical shaft,
* Where the ducts pass through floors, and
* At the inlet of supply air ducts and the return air duct of each compartment in every floor.
**D9.2.1** The fire dampers shall come into operation when air handling fans shall switch off. Devices with manual operations shall also be made available. Blowers using extraction and dust accumulation system shall be provided with dampers.
**D9.2.2** For smoke extraction, smoke dampers shall be installed in building of 26 m or more in height. In apartment houses, non-ventilated lobbies and corridors shall be covered by smoke dampers operated by fusible link and also manual control. In other buildings operation of dampers shall be manual in nature.
**D9.2.3** Operated by fusible link, automatic fire dampers shall be so arranged as to be closed by gravity in the direction of air movement and shall remain tightly closed.
### D10 GAS SUPPLY
**D10.1** Gas supply in tall buildings shall be from city gas main or L.P gas and shall conform to the provisions detailed in Chapter 8, Part 8.
**D10.2** Gas pipe lines shall run in exclusive shafts on external walls and shall be away from staircase. These shafts, shall be exclusive for each floor. L.P. gas distribution pipes in shortest possible run shall always be below false ceiling. Entire cooking range area in the kitchen shall be covered by an exhaust system of 50 mm²/per m² of hood projected area. The hood shall be fitted with metallic grease filter to trap oil vapour of the smoke.
**D10.3** Power line wiring in the fume hood shall be in fibre glass insulation. Kitchens for hotels, hospitals or such other places in high rise buildings shall have heat detectors fixed in fume hood which will automatically cutoff LP gas and trip off exhaust fan in case of fire. Actuation of the devices shall be by 24v or 100v DC with external rectifier.
### D11 BOILER LOCATION AND BOILER ROOMS
The following provisions shall be complied with for location and housing of boilers.
**D11.1** Boiler shall be allowed to be installed in basement away from escape route but shall not be allowed in sub-basement.
**D11.2** Boiler room shall be situated on the periphery of the basement and shall have a 4 hour fire resistance wall. Floor shall be sloped to a catch pit.
**D11.3** For fresh air supply to the boiler room, it shall be fitted with air inlets and smoke exhaust system directly open to the atmosphere.
**D11.4** Entry to boiler room shall be through a 2 hour fire resistance composite door.
**D11.5** Furnace oil for boiler, if stored in oil tank in an adjacent room, shall be separated by a 4 hour fire resistance wall. Entrance to this room shall be controlled by double composite doors. To prevent spread of accidental spillage of furnace oil, a suitable curb shall be erected at the entrance door opening.
**D11.6** For the convenience of Fire Department personnel to work with foam from outside the building, suitable foam inlet facilities shall be in built on the external wall.
### D12 STAIRCASE AND CORRIDOR LIGHTS
Staircase and corridor lights shall comply with the following provisions.
**D12.1** The staircase and corridor lighting shall be connected to a separate independent circuit so that at times of emergency the fire fighting personnel can operate the same from an easily accessible location on the ground floor disregarding individual control of light points. The circuit shall be equipped with a miniature circuit breaker type of switch.
**D12.2** To avoid connection to two sources of supply at the same time, lighting installed in the staircase and corridor shall be suitably mounted on a double throw switch. To terminate standby supply, double throw switch shall be installed in the service room.
**D12.3** Staircase and corridor lighting shall also be connected with an alternate supply.
**D12.4** Staircase and corridors shall be provided with emergency lights.
### D13 ELECTRICAL SERVICES
Electrical Services shall confirm to the following provisions.
**D13.1** The electric distribution cables and wiring shall run through separate ducts. The duct shall be sealed with noncombustible materials at every floor level having the same fire resistance rating of that of the duct. Low and medium voltage wiring running in shafts and false ceiling shall run in separate conduits.
**D13.2** The duct carrying the electric cable shall not contain any other services like water mains, telephone lines, intercom lines, gas pipes etc.
**D13.3** Electric power supply to water pumps, lifts, staircases, corridor lighting and blowers to keep pressure system running shall directly be provided through main switch gear panel. Power lines shall be laid in separate conduit pipes, so that fire in one circuit will not affect the others. Master switch circuit elements shall be clearly labeled.
**D13.4** Doors and inspection panel doors in the shaft shall be fitted with air-tight fire doors having fire rating of at least 2 hours.
**D13.5** Medium and low voltage power lines in the shaft and within false ceiling shall run within metal conduits. 220v wiring for lighting and other services above false ceiling shall have a 660v grade insulation. The false ceiling and all the materials and fixtures used its suspension shall be of noncombustible materials.
**D13.6** Electricity supply from the public authority and alternate supply cables shall lead to an independent well ventilated room on the ground floor for the purpose of termination for eventual distribution into the building. The door fitted in the service room shall be at least 2 hours fire resistance rated.
**D13.7** If the power authority agrees to install meters on upper floors, the authority and consumer cable lines shall be separated by a partition in the duct. Meter rooms on upper floors shall not open on staircase and shall be directly ventilated to open air outside.
### D14 STANDBY GENERATOR
The standby generator shall comply with the following.
**D14.1** A standby electric generator shall be installed to supply power for staircase and corridor lighting, fire lifts, standby fire pump, pressurization fans and blowers, smoke extraction and damper systems in case of failure of normal electricity supply.
**D14.2** The generator shall be capable of taking starting currents of all the machines and circuits stated above simultaneously.
**D14.3** When the standby pump is connected to diesel engine for supply of power, the pump may be withdrawn from standby generator supply.
**D14.4** For emergency, if supply is available from a separate sub-station with appropriate transformer, the provision of generator may be waived with the approval of power authority.
### D15 TRANSFORMER
Transformers shall conform to the following provisions.
**D15.1** Without proper oil drainage arrangement, a sub-station or a switch station along with accompanying machines having more than 2000 litres oil shall not be located in the basement of the building in normal circumstances. Transformers, when housed below ground level, shall be housed in the first basement in a separate 4 hour rated room located on the periphery of the basement floor. The entrance to this room shall have a fire resisting door of 2 hour fire rating. To prevent spread of accidental spillage of oil, a suitable curb shall be erected at the door opening. Direct access preferably from outside shall be provided to the transformer room. Switch gears and transformer bays shall be separately housed with a 4 hour fire rated wall in between.
**D15.2** When housed in basement, transformer rooms shall be equipped with automatic high velocity water spray system.
**D15.3** When a transformer is housed in complete segregation by a 4 hour fire rated wall all around and has direct access from outside, the transformer room may be protected by CO2 (carbon dioxide), BCF (Bromo-chlorodifuoromethane) or BTM (Bromo-triflouromethane) fixed system.
**D15.4** When the transformer is on the ground level, the room shall be completely segregated from rest of the premises by 4 hour fire rated walls all around.
**D15.5** Oil filled transformers shall not be housed above ground level.
**D15.6** Where aggregate oil capacities of all machines do not exceed 200 litre, they shall be provided with a catch pit. When the aggregate capacity exceeds 200 litre, an RCC tank capable of holding the entire need shall be provided at lower level to collect the oil from catch pit in case of emergency. The connection between catch pit and tank shall be of noncombustible construction and provided with a flame arrester.
### D16 FIRST AID FIRE FIGHTING APPLIANCES
First aid fire fighting appliances shall be provided on all floors, basements, lift room etc. as required by the authority. Location and distributions of fire fighting appliances shall also be as required by the authority.
### D17 FIRE ALARM SYSTEM
Fire alarm system shall comply with the following provisions.
**D17.1** All buildings with a height of more than 20 m shall be equipped with manually operated electrical fire alarm system and automatic fire alarm system. Offices and apartment buildings between 20 and 26 m in height, however, may be exempted from installing automatic fire alarm system, if they do not pose threat towards safety of adjacent buildings and inmates of the buildings itself are safe in the opinion of the authority.
**D17.2** Manually operated electrical alarm system shall be installed in a building with single or multiple call boxes located on each floor and shall conform to:
a) location of call boxes shall be decided after careful review of the floor plan so that all the occupant can approach to any one of the call box without having traveled more than 22.5 m
b) Usually call boxes shall be of the type having no moving parts, but in case they have, they are to be approved by the authority to ensure timely function. Usual boxes shall be "break glass" type and the act of breaking the glass shall constitute fire alarm transmission to the command station.
c) All call boxes shall be wired in a closed circuit to a control panel in the command station which clearly indicates the origin or location of the alarm. The circuit shall be equipped with a rechargeable battery with capacity for full normal working load for 2 days. The circuit may be connected to an alternate source of supply.
d) The call boxes shall be installed 1 m above the floor on the corridor or passage so that they are easily visible, yet do not obstruct the safe means of egress at times of emergency.
e) The call boxes are installed to actuate single or multiple sounders so that all inmates can hear the alarm.
### D18 COMMAND STATION
All buildings above 26 m in height shall have a command station on the entrance lobby with suitable public address system having communication to all floors as well as facilities to receive messages from all floors. The command station shall be equipped with detailed floor plans along with clearly demarcated locations of fire detection and fighting devices and through the panel board able to detect fire alarm from any floor. The command station shall be manned with properly trained personnel having responsibility of maintenance and operating fire fighting facilities within the building.
### D19 CARETAKER/FIRE OFFICER
All residential, business, hotels, and other buildings having height more than 53 m shall keep standby one trained fire officer round the clock. He shall be responsible for:
a) Maintaining fire fighting equipment in good working condition all the time.
b) Layout fire orders and operational plans.
c) Impart training to inmates of the building in handling available equipment and keep them informed of fire crisis and evacuation plan.
d) Keep contact with local fire authority.
### D20 HOUSE KEEPING
To reduce or minimize fire hazard, strict house keeping within and outside shall be strictly maintained by the occupants and owner of the building.
### D21 FIRE DRILLS
Fire notices or orders shall be prepared in fulfilment of the requirements for fire fighting and evacuation in case of fire or other emergency. Such notices and orders shall be so displayed as to make the occupants well conversant with needed action in the event of emergency. Details of fire drill are specified in Appendix A.
# Chapter 1: General Provisions
Source: https://docs.sayed.app/bnbc2006/part-4-fire-protection/chapter-1-general-provisions
## 1.1 SCOPE
This part of the Code prescribes regulations for safeguarding life and property in the use or occupancy of buildings or premises from the hazards of fire and explosions. The provisions of this part include general requirements of fire protection, precautionary requirements for resisting a fire, means of escape requirements, equipment and in-built facilities required for fire fighting, and fire fighting arrangements required for various occupancy groups.
## 1.2 TERMINOLOGY
This section provides an alphabetical list of the terms used in and applicable to this part of the Code. In case of any conflict or contradiction between a definition given in this section and that in Part 1, the meaning specified in this part shall govern for interpretation of the provisions of this part.
**ALARM CONTROL UNIT :** It consists of a circuit, controls, relays, switches and associated system which receive signals from alarm initiating devices and transmit to alarm signalling devices.
**ALARM INITIATING DEVICE :** An equipments operated manually or automatically which, when activated, initiates an alarm through an alarm signalling device.
**ALARM SIGNAL :** Signals of audible or visual nature or both, indicating the existence of a fire condition. Audible devices may be bells, horns, chimes, speaker or similar devices.
**ALARM SIGNAL DEVICE :** The equipment that produces the alarm signal.
**ALARM SYSTEM :** It is a combination of compatible devices, which when activated with necessary electrical energy can produce an alarm in the event of fire.
**ALARM ZONE:** It describes a defined area of the building or buildings for alarm initiating locations.
**ANNUNCIATOR :** Equipment capable of indicating the zone or area of a building from which an alarm has been initiated or the location of such devices and the operational condition of alarm circuit of the system.
**AUTOMATIC FIRE DETECTING AND ALARM SYSTEM :** These include all types of fire detecting and alarm signalling devices which activate themselves during a fire without manual intervention. The equipment/ devices include temperature sensitive fuses, thermostat, fluid filled tubes and electronic devices which can detect a fire and transmit automatic alarm signals.
**AUTOMATIC SPRINKLER SYSTEM :** The system consists of an array of pipe works fitted with fusible solder or glass bulb in a predetermined temperature fed from town main, elevated private reservoir, gravity tank, pressure tank or automatic pump supply and other connecting equipment which operate automatically by sensing the heat of fire and discharge water to extinguish it. These devices also actuate an audible alarm automatically.
**AUTOMATIC HIGH VELOCITY WATER SPRAY :** This system applies water in the form of a conical spray of droplets of water discharged at high velocity through specially designed projectors to extinguish fire by emulsification, cooling and smothering. High velocity system is used for the protection of medium and heavy oils or similar flammable liquids.
**CARBON DIOXIDE EXTINGUISHING SYSTEM :** This installation consists of a group of one or more cylinders of carbondioxide, interconnected by a manifold and feeding into a system of high pressure distribution pipework fitted with special discharge nozzles.
**COMBUSTIBLE MATERIAL :** Any material which burns and enhances the magnitude of fire.
**DOWN COMER :** See WET RISER-CUM-DOWN COMER STANDPIPE SYSTEM.
**DRY-CHEMICAL EXTINGUISHING SYSTEM :** This system consists of specially designed pipe works and discharge nozzles linked to the dry powder containers and CO2 cylinders which are automatically / manually operated in case of fire.
**DRY RISER :** A dry riser is a vertical pipe which is normally kept empty of water, fitted with outlets at various floor levels in the building. It is not connected to a water supply, but is charged when required, by means of fire pumps.
**FIRE EXIT :** A continuous and unobstructed means of escape to a public way, which includes doors, corridors, stairway, aisles, gates, balconies, ramps, horizontal exits, fireproof enclosures etc.
**FIRE RESISTANCE RATING :** It denotes the resistance of a building construction material and/or construction itself and is expressed as a period of time during which the materials/constructions are (a) resistant to collapse due to fire, (b) resistant to flame penetration and (c) resistant to excessive temperature rise on the unexposed surface.
**FIRE SEPARATION :** Horizontal or vertical fire resistance rated assembly of materials having protected openings or a clear area around a building for the purpose of preventing the spread of fire.
**FIRE TOWER :** These are open to outer air staircases separated from any building which can be approached from various floors of a building by connecting corridors, landings or lobbies and are separated from the floor area and main staircase by fire resisting doors.
**FIRE WALL:** A fire resistance rated wall having protective openings, which is constructed from the ground level to at least 1m above the roof of a building to restrict the spread of a fire.
**FOAM EXTINGUISHING SYSTEM :** This system operates automatically / manually to extinguish special fires. It consists of several types, of which pump proportioned mechanical foam type, self contained pressurised type and pre-mixed foam types are commonly used.
**HALOGENATED EXTINGUISHING SYSTEM :** This system consists of distribution of pipe works and specially designed nozzles which are sited strategically around the fire risk zone. The chemicals are kept under pressure and released automatically / manually in case of fire. At present only B.T.M. (HALON-1301) is internationally recommended for fixed system.
**HORIZONTAL EXIT :** An escape system which connects a floor horizontally with an adjacent structure at or near the same level.
**ROOF EXIT :** The exit which opens at the roof and is accessible from the ground level.
**SMOKE DETECTOR :** A devise capable of sensing visible or invisible particles produced during combustion.
**TRAVEL DISTANCE :** The travel distance of an escape route from a location within the building.
**VENTILATION :** Natural or mechanical intake of fresh air from outside and removal of trapped air of an enclosed space.
**VENT (FIRE) :** A system which activates itself automatically during a fire or can be activated manually to release the heat and smoke generated by the fire and prevents lateral spread of fire and smoke.
**WET-CHEMICAL EXTINGUISHING SYSTEM :** A system where a solution of water and potassium carbonate and/or potassium acetate based chemical forms the extinguishing agent.
**WET RISER-CUM-DOWN COMER STANDPIPE SYSTEM:** Wet riser consists of an array of pipes installed vertically in a building with outlets (landing valves) at various levels throughout the building containing permanently charged water at a specified pressure for fire fighting purposes.
'Down comer' is similar in function to that of a Wet Riser which is constructed as vertical piping, but is supplied with water from a tank on the roof or at intermediate levels.
## 1.3 GENERAL REQUIREMENTS
The provisions of this section shall govern the general requirements in respect of height and area limitations, open space requirements and access facilities for the fire service, which are to be provided for a building to protect it from potential fire hazards.
### 1.3.1 Height and Area Limitation
The height and area limitations of all buildings and structures shall be governed by the occupancy group classification, Floor Area Ratio and type of construction, which are specified in Sec 1.8 of Part 3.
### 1.3.2 Open Space Requirement
For the purpose of applying the above regulations on open space requirements of a building at its side, rear and front, Sec 1.7, Part 3 of this Code shall be followed.
### 1.3.3 Access Facilities for Fire Service
The access facilities for fire service vehicles and engines shall meet the following requirements.
#### 1.3.3.1
Fire apparatus access roads shall have an unobstructed width of 4.5 m and the minimum vertical clearance shall be 5 m. The width and vertical clearance of fire apparatus access roads may be increased when in the opinion of the fire authority, the clearances are not adequate to provide fire apparatus access.
#### 1.3.3.2
Fire apparatus access roads having a dead end longer than 30 m from the main road shall be provided with appropriate provisions for turning around of the fire apparatus.
#### 1.3.3.3
The fire apparatus access road shall be marked by an approved sign.
## 1.4 FIRE DRILL
Fire drills based on fire order shall be arranged to train the occupants of a building in fire fighting and evacuation. The occupants shall be made thoroughly conversant with fire order, fire fighting and evacuation procedures in the event of an emergency.
The guidelines of fire drill and evacuation procedure are given in Appendix A.
## 1.5 FIRE TESTS AND FIRE RESISTANCE RATING
The fire resistance rating of individual building construction components shall be determined by standard materials testing procedure as detailed below.
### 1.5.1
The fire resistance ratings of building assemblies and structural elements shall be determined in accordance with ASTM E 119.
### 1.5.2
The construction materials which are intended to be classified as noncombustible shall be tested in accordance with ASTM E 136.
### 1.5.3
Flame resistance rating of all materials used for interior finish and trim shall be tested in accordance with ASTM E 84.
### 1.5.4
The fire door assemblies shall conform to the test requirements of ASTM E 152.
### 1.5.5
The fire windows and fire shutters shall meet the test requirements of ASTM E 163.
### 1.5.6
The fire resistance rating of structural elements, which are widely used in Bangladesh, are provided in Table 4.1.1 below, as a guideline. These ratings shall be used unless tests conducted in accordance with the above indicate higher fire resistance ratings, in which case the higher values may be used.
#### Table 4.1.1 Fire Resistance Rating of Common Construction Elements
| Structural Element | Fire Resistance Rating |
| :------------------------------------------------------ | :--------------------- |
| **75 mm thick walls of clay bricks** | 0.75 hour |
| **125 mm thick walls of clay bricks** | 1.5 hours |
| **250 mm thick walls** | 5.0 hours |
| **150 mm thick RC wall** | 3.0 hours |
| **200 mm thick RC wall** | 4.0 hours |
| **250 mm thick RC walls** | 5 hours |
| **300 mm thick RC walls** | 6 hours |
| **100 mm RC slabs with 13 mm cover over reinforcement** | 1 hours |
| **150 mm RC slabs with 19 mm cover over reinforcement** | 2.5 hours |
| **200 mm RC slabs with 19 mm cover over reinforcement** | 3.75 hours |
| **250 mm RC slabs with 25 mm cover over reinforcement** | 5.0 hours |
| **RC COLUMNS (1:2:4)** | |
| **250 mm x 250 mm with 25 mm cover over reinforcement** | 3.0 hours |
| **300 mm x 300 mm with 25 mm cover over reinforcement** | 4.0 hours |
| **400 mm x 400 mm with 25 mm cover over reinforcement** | 6.0 hours |
| **400 mm x 400 mm with 50 mm cover over reinforcement** | 8.0 hours |
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# Chapter 2: Precautionary Requirements
Source: https://docs.sayed.app/bnbc2006/part-4-fire-protection/chapter-2-precautionary-requirements
## 2.1 OCCUPANCY CLASSIFICATION
All buildings shall be classified according to their use or by considering the character of their occupancy. For the purpose of this Code, the occupancy classification groups shall be as follows:
Occupancy A: Residential\
Occupancy B: Educational\
Occupancy C: Institutional\
Occupancy D: Health Care\
Occupancy E: Assembly\
Occupancy F: Business and Mercantile\
Occupancy G: Industrial\
Occupancy H: Storage\
Occupancy J: Hazardous\
Occupancy K: Miscellaneous
The details of occupancy classification of buildings are provided in Sec 2.1 of Part 3.
## 2.2 CLASSIFICATION OF CONSTRUCTION TYPES
All buildings and structures to be constructed, altered and/or extended in height or area shall be classified in any one or in a combination of the following three construction types:
Type 1 : Highest degree of fire resistance\
Type 2 : Intermediate degree of fire resistance\
Type 3 : Lowest degree of fire resistance
The types of construction are based on fire resistance of construction elements, which are detailed in Sec 3.1 of Part 3.
## 2.3 FIRE ZONES
The fire zones shall divide the development areas of a city, township or municipality into three distinct areas based on the inherent fire hazards of the buildings to be constructed and the degree of safety desired for the occupancy group accommodated therein.
## 2.4 MIXED OCCUPANCY
Mixed Occupancy shall be allowed only when the occupancies are separated by fire resistant walls as specified in Sec 2.3 of Part 3. Mixing of occupancy group J (Hazardous occupancy) with other groups shall not be allowed.
## 2.5 OPENINGS IN SEPARATING WALL
### 2.5.1
The openings in occupancy separation wall shall conform with the provisions set forth in Sec 2.3.3, Part 3.
### 2.5.2
Openings in fire separating walls and floors shall not exceed the approved limit and the opening shall be of protective type and conform to the approved provisions.
### 2.5.3
Fire separating walls shall not have opening exceeding 11.2 m² in area and the aggregate width of all openings at any floor level shall not exceed 25 per cent of the length of the wall. When the entire first storey floor area on both the sides of a fire separating wall are covered by automatic fire suppression system, the maximum allowable opening may be doubled with a minimum distance of 0.9 m between adjacent openings.
### 2.5.4
Doors and other openings in Type 1 construction (opening in a separating wall) shall be limited to 5.6 m² in area with a maximum height of 2.75 m and width of 2.1 m. Wall openings shall be protected with approved fire resisting means like fire doors or steel rolling shutters conforming to approved standards. All openings in floors shall be protected by vertical enclosures extending above and below such openings. Walls of such opening enclosure shall have at least 2 hours fire resistance rating.
### 2.5.5
Openings of service lines like cables, electrical wirings, telephone cables, plumbing fixture etc. shall be protected by enclosures having a fire resistance rating of not less than 2 hours. Medium or low voltage electrical wire running through shaft or ducts shall be either armoured or cased within metal conduits.
### 2.5.6
All openings in the separating walls and doors shall be provided with minimum 2 hours fire resistance assemblies in Type 3 construction.
## 2.6 SMOKE AND HEAT VENTS
### 2.6.1
Smoke and heat vents shall be installed in single storeyed windowless buildings, underground structures, factories with large floor spaces and other areas of restricted ventilation.
### 2.6.2
Where exit access travel distance is more than 25 m, smoke and heat vents shall be constructed in accordance with the provisions of this Code.
### 2.6.3
The vent area and spacing of the vents shall comply with Table 4.2.1.
#### Table 4.2.1 Smoke and Heat Vent Size and Spacing
| Use group | Hazard Condition | Vent Area to Floor Area Ratio | Max Spacing of Vent Centres |
| :----------- | :--------------- | :---------------------------: | :-------------------------: |
| Occupancy G1 | Low Hazard | 1:100 | 30 m |
| Occupancy G2 | Moderate hazard | 1:75 | 20 m |
| Occupancy H1 | Low Hazard | 1:100 | 30 m |
| Occupancy H2 | Moderate Hazard | 1:75 | 20 m |
| Occupancy J1 | High Hazard | 1:30 | 15 m |
| Occupancy J2 | High Hazard | 1:30 | 15 m |
| Occupancy K1 | Low Hazard | 1:100 | 30 m |
### 2.6.4
Closures of natural draft, smoke and heat vents shall be installed in such a way that fire service personnel can open it easily during a fire.
### 2.6.5
Smoke and heat vents on roof or ceiling or wall shall normally be kept open. In case of closed vents, automatic activation of the openings by heat-responsive device rated at 38°C to 104°C above ambient shall be a requirement. The releasing mechanism shall be capable of opening the vent fully when the vent is exposed to a time-temperature gradient that reaches an air temperature of 260°C within 5 minutes. The vents shall also be capable of being opened by manual operation.
### 2.6.6
Venting requirements for Industrial and Storage Buildings are given in Appendix B.
## 2.7 ELECTRICAL, GAS AND HVAC SERVICES
### 2.7.1
The requirements of the electrical, HVAC and gas services shall meet the provisions of Chapters 2, 3 and 8 respectively of Part 8.
### 2.7.2
Air-conditioning and ventilation systems shall be installed and maintained in such a manner that the fire, fumes or smoke do not spread from one floor or area of fire to other parts of a building through the ducts or vents.
### 2.7.3
Properly designed fire dampers shall be installed within the air-conditioning and ventilation ducts, which shall automatically close the flow of air in case of fire.
### 2.7.4
For large assembly areas, department stores and hotels with more than 100 rooms in a single block, effective means of preventing circulation of smoke through the air-conditioning ducts shall be installed. Such means shall consist of approved photo-electric or other smoke sensing control devices, as the fuses and dampers may not function during early state of a fire due to insufficient heat.
## 2.8 SURFACE FINISHES
### 2.8.1
Plastic, wood or other flammable materials used to trim and cover the interior and exterior facade of a building structure have the potential of generating smoke and toxic fumes during a fire and have the potentiality of changing the nature of fire due to its ignitability as fuel.
### 2.8.2
The fire susceptibility of various types of surface finishes are determined in terms of the rate of spread of fire (ASTM E 84-87). Based on the rate of spread of fire, the surface finish materials shall be classified into 3 classes:
Class I Surfaces of low flame spread: Flame does not effectively spread more than 300 mm in the first 1.5 minutes with an ultimate value of 600 mm.\
Class II Surfaces of medium flame spread: Flame does not spread effectively more than 300 and 850 mm in the first 1.5 and 10 minutes respectively.\
Class III Surfaces of rapid flame spread: Flame spreads effectively more than 300 and 850 mm in the first 1.5 and 10 minutes respectively.
### 2.8.3
Interior finish of walls and ceilings shall have a flame spread rating not greater than those in Table 4.2.2 for various occupancy classes.
#### Table 4.2.2 Acceptable Flame Spread Rating Classes of Interior Finish
| Use Group | Vertical Exits and Passage Ways | Corridors Providing Exit Access | Rooms or Enclosed Areas |
| :----------------------------------------------- | :-----------------------------: | :-----------------------------: | :---------------------: |
| A1 - Detached single family dwelling | III | III | III |
| A2 - Flats or Apartments | I | I | I |
| A5 - Hotels and lodging Houses | I | I | I |
| B - Educational | I | I | I |
| C1 & C2 - Institutional, Residential & Custodial | I | I | III\* |
| C3 - Institutional - Incapacitated | I | I | I |
| C4 - Institutional - Restrained | I | I | I |
| D - Health Care | I | I | I |
| E1 - Large assembly with fixed seats | I | I | I |
| E2 - Small assembly with fixed seats | I | I | I |
| E3 - Large assembly without fixed seats | I | I | I |
| E4 - Small assembly without fixed seats | I | I | I |
| F - Business & Mercantile | I | II | II |
| G - Industrial | I | II | II |
| H - Storage | III | II | III |
| J - Hazardous | I | II | III |
*Class II may be adopted in case the area is covered by automatic fire suppression system.*
## 2.9 GLAZING
### 2.9.1
Buildings of construction Type 1, 2 and 3 shall use any one of the following types of glazing (covered under Sec 2.9.2 and 2.9.3) using wire glass and square formed by electro-copper. Building of construction Type 3, may use hardwood sashes or frames or both.
### 2.9.2 Wired Glass Panels
Wired glass panels shall comply with the following requirements :
a) Thickness of the glass shall not be less than 6 mm.
b) Embedded wire netting mesh in the glass shall not be more than 25 mm mesh.
c) The sashes or frames or both shall be entirely made up of iron or any other approved metal. The frame shall be securely fixed into the wall (except panels of internal doors).
d) Setting of the panels of glass shall be achieved by rebates or grooves of not less than 6 mm width or depth keeping due allowance for expansion. The glass shall be secured to the frame by hard metal fastenings. Lead, cement or putty may be used for weather proofing.
Where wired glass panels are labeled as protective openings, they shall conform to the size limitations shown in the Table 4.2.3.
#### Table 4.2.3 Size limitations of Wire Glass Panels
| Fire Rating/Opening | Max Height in m | Max Width in m | Max Area in m² |
| :--------------------------------------------- | :-------------: | :------------: | :------------: |
| 3 hours (not permitted) | -- | -- | -- |
| 1½ hour door in exterior walls (not permitted) | -- | -- | -- |
| 1½ hour fire rating | 0.85 | 0.25 | 0.065 |
| ¾ hour fire rating | 1.4 | 1.4 | 0.85 |
| Fire windows | 1.4 | 1.4 | 0.85 |
### 2.9.3 Electro-copper Glazing
Electro-copper glazing shall comply with the following requirements:
a) Thickness of the glass shall not be less than 6 mm.
b) Not more than 0.4 m² of square glass shall be formed by electro-copper glazing in sectional lights.
c) The sashes or frames or both shall be entirely made up of iron or any other approved metal. The frame shall be securely bolted into the wall (except panels and internal doors).
d) Setting of the panels of glass shall be achieved by rebates or grooves of not less than 6 mm width or depth keeping due allowance for expansion. The glass shall be secured to the frame by hard metal fastenings. Lead, cement or putty may be used for weather proofing.
### 2.9.4
Wall openings more than 5 m² shall not be deemed to be of effectively protected by wired glass or electro-copper glazing.
### 2.9.5
Wired glass or electro-copper glazing not exceeding 0.85 m² in area shall be allowed provided it is cased in hard metal and secured to the frames by hard metal hinges not exceeding 60 mm apart and by fastening at top, centre and bottom.
## 2.10 SKYLIGHTS
### 2.10.1
Wired glasses used in skylights shall comply with the following requirements:
a) Thickness of the glass shall not be less than 6 mm;
b) Wire netting mesh embedded in the glass shall not be more than 25 mm square;
c) The glazing shall be cased in frame of continuous metal divided by bars 750 mm apart centre to centre. The frame and bars shall be iron or other approved metal (or of hard wood covered with sheet metal).
d) The glass shall be secured to the frame by hard metal fastenings. Lead, cement or putty may be used for weather proofing.
### 2.10.2
Skylight openings more than 5 m² shall not be deemed to be effectively protected by wired glass.
## 2.11 FIRE LIFTS
### 2.11.1
Fire lifts shall be used in buildings more than 20 metre in height. Fire lifts, where used shall be fully automated from the ground level with approved wiring and switches and shall have a minimum capacity of 8 persons.
### 2.11.2
Fire lifts may be operated by the inmates of the buildings except during fire. During fire, only firemen shall operate such lifts.
### 2.11.3
Fire lifts shall be equipped with approved intercommunication (including two way voice communication) with the fire command station or control room on the ground floor lobby of the building.
### 2.11.4
Number and location of fire lifts in a building shall be decided on the basis of total occupant load, floor area and compartmentation.
## 2.12 SPECIAL HAZARDS
The various occupancy groups are exposed to fire hazard of different nature and intensity, which are detailed below under different occupancy classes.
### 2.12.1 Special Hazards in Occupancy A : Residential
a) Flammable liquids used for domestic purposes shall be kept adequately sealed in approved containers at all times.
b) Stoves and heaters using open flame or otherwise shall be so located as not to create any obstruction on the escape route in case of fire. Such appliances shall not be located directly on or near the foot of stairs.
c) Exhaust fans used in kitchens shall be placed on a peripheral wall of the building or to a duct connected directly to outside and shall be made of noncombustible material. The duct shall not pass through combustible materials.
d) Doors leading into a room containing flammable liquids shall be provided with self closing devices. Appropriate signs identifying the storage materials and requesting the users to keep the door closed shall be marked on both sides of the door.
e) All outdoor television antenna shall be properly grounded and protected against lightning.
f) Rooms containing boiler using liquid or solid fuel shall be separated from the main building by appropriate separation wall with all its openings protected as per provisions detailed in Sec 2.3 of Part 3 and Sec 2.5 of this Chapter.
g) Rooms containing high pressure boilers, refrigerating machinery, transformers or such other equipment necessary for extending services to inmates of such occupancies shall be so located that these do not block the means of escape. Such rooms shall be effectively segregated from the main occupancy area and shall be provided with adequate venting to outside.
h) Areas or rooms within the building identified as hazardous occupancy shall be protected or segregated by appropriate separation wall or by other approved means as directed by the Authority.
### 2.12.2 Special Hazards in Occupancy B : Educational
a) Rooms or areas containing volatile flammable liquids shall be separated from the adjoining areas in accordance with Sec 2.3 of Part 3 and Sec 2.5 of this chapter.
b) Gas pipeline entering any building shall be equipped with shutoff valves outside the building with conspicuous marking clearly delineating the location. (See Chapter 8 of Part 8).
c) The exterior openings of boiler rooms shall be adequately protected by fixed, automatic or self closing fire assemblies.
### 2.12.3 Special Hazards in Occupancy C: Institutional
Permit shall not be granted for storage or handling of any hazardous material, except for normal use in amounts not exceeding the exempted amounts specified in Chapter 2 of Part 3, in a building or part thereof classified as Occupancy C.
### 2.12.4 Special Hazards in Occupancy D: Health Care
Storage of volatile flammable liquids such as chloroform, ethyl alcohol, mentholated spirit etc. shall be stored in safe storage and no unauthorized person shall be allowed to handle such liquids.
### 2.12.5 Special Hazards in Occupancy E: Assembly
a) All materials used for decorative purposes in buildings of Occupancy E shall be noncombustible. If fabric and papers are used for decorative purposes those shall be treated with flame resistant chemicals/materials.
b) Assembly buildings primarily meant for theatrical, operatic or cinematic performances shall have the seats securely fastened to the floor with exceptions as permitted in 2.12.5 (c) below. All seats in balconies and galleries shall be securely fastened to the floor except boxes with level floor and less than 14 seats.
c) Seats not fixed to the floor shall be permitted in restaurants and such other places provided that 1.25 m² of floor space is allotted for every seat excluding dancing floor and stage. Adequate aisles shall be maintained at all times to reach exits without obstruction when such occupancies are in use.
i) Not more than 14 seats shall be allowed in one row between aisles.
ii) 50 per cent of seats in a row shall have one opening of an aisle.
iii) Capacity of seats without dividing arms shall be calculated at the rate of 450 mm per person.
iv) The minimum space between rows of seats shall be 850 mm and space between the back of one seat and the front of the seat immediately behind shall not be less than 350 mm measured between plumb lines.
v) Rooms and parts of a building containing high pressure boilers, refrigerating machinery, large transformer or other service equipment having explosion potential shall not be located on or adjacent to the defined exit route. Such rooms shall be effectively cut off from the rest of the building and connected to open air through approved ducts or openings.
e) Rooms or parts of a building used for storage of combustible materials such as paints or other items shall be effectively cut off from main assembly building or protected by approved automatic sprinkler system. Such areas shall be away from staircases.
f) Stages having such facilities as fly galleries, gridirons and rigging shall be covered by an automatic sprinkler system above and below such stage areas or spaces. Auxiliary spaces such as dressing rooms, store rooms, and workshops and the proscenium opening shall be effectively covered by fire resistant curtains capable of withstanding a lateral pressure of 4 kN/m². The curtain shall be equipped with self closing emergency device and when closed shall be tight enough to prevent spread of smoke.
g) Stage roof above every theatre using movable scenery or motion picture screen constructed of highly combustible materials shall be fitted with ventilators in or above it. The ventilators shall be openable from the stage floor manually or by fusible links or some approved automatic heat actuated device to give an opening to sky with an area of one-eighth the area of the stage.
h) In theaters not protected by automatic fire sprinklers, the proscenium wall using movable scenery of decorations shall be provided with maximum of two openings to enter the stage and each opening shall not be of more than 2 m².
i) Film projection apparatus shall be enclosed within fire resistant enclosures.
j) Auditoriums of theaters and cinemas shall be installed with vents on roof having vent area equal to 1/30 th the floor area including balconies and galleries, boxes and tiers. Larger numbers of smaller vents shall be preferable over smaller number of larger vents.
### 2.12.6 Special Hazards in Occupancy F : Business and Mercantile
a) Exit aisles or approaches in self-service stores shall not be obstructed by placing check out stand with associated railings or barriers on its passage.
b) All operations in open air markets, petrol filling stations, road side stands for sale of farm products etc. shall be so conducted that unobstructed access to exits are always maintained.
### 2.12.7 Special Hazards in Occupancy G : Industrial
a) No apparatus generating flames capable of igniting flammable vapour shall be permitted within a room or part of a building using or storing volatile flammable liquid. Rooms or parts of a building using or storing such flammable liquid shall be covered by exhaust ventilation system.
b) Boiler rooms and areas containing heating plants shall be effectively segregated from the rest of the occupancy.
c) Adequate protective measures shall be taken against hazards associated with distribution and use of electricity and gas in accordance with the provisions of Chapters 2 and 8 of Part 8.
d) Automatic sprinkler or other protections like installation of vents shall be made in all buildings of Occupancy G2 (Moderate Hazard Industries).
e) The machine layout shall be congenial to safe fire practice.
### 2.12.8 Special Hazards in Occupancy H : Storage
a) No apparatus generating flames capable of igniting flammable vapour shall be permitted within a room or part of a building using or storing volatile flammable liquid. Rooms or parts of a building using or storing such flammable liquid shall be covered by exhaust ventilation system.
b) Boiler rooms and areas containing heating plants shall be effectively segregated from the rest of the occupancy.
c) Adequate protection shall be taken against hazards associated with distribution and use of electricity and gas in accordance with the provisions of Chapters 2 and 8 of Part 8.
d) Automatic sprinkler or other protections like installation of vents shall be made in all buildings of Occupancy H2 (Moderate Fire Risk Storage).
### 2.12.9 Special Hazards in Occupancy J : Hazardous
a) Equipment, machinery and operations emitting combustible volatile substances shall be protected with dry chemical, foam or CO₂ fire extinguishing system.
b) Dry cleaning machines using flammable liquids shall be directly connected to a steam line. Arrangements shall be so made that in case of explosion, steam will be automatically released inside each machine.
c) Except wall vents, all openings in exterior walls shall be protected by fixed, automatic or self closing fire assemblies. Wall vents shall be placed near the floor line having openings not less than 0.01 m² each and distance between two successive vents shall not be more than 1.8 m. Power driven exhaust fans for ventilation in every building shall be so arranged and operated that a complete change of air is affected every 3 minutes.
d) Gas inlet pipes shall be fitted with gas shutoff valves outside the building and marked conspicuously for ready recognition.
e) Rooms containing boiler or heating plant shall be effectively separated from the main building by a separating wall.
f) Devices capable of generating spark and glow flame that can ignite gasoline vapour, shall not be installed or permitted in rooms where volatile flammable liquids are used or stored unless the area is enclosed with a flame-proof enclosure.
> \[!NOTE]
> **Related Appendix:**
> Appendix B Fire Protection Considerations for Venting in Industrial and Storage Buildings
# Chapter 3: Means of Escape
Source: https://docs.sayed.app/bnbc2006/part-4-fire-protection/chapter-3-means-of-escape
## 3.1 SCOPE
The provisions of this section shall control the design, construction and arrangement of building components to provide a reasonably safe means of escape therefrom. Buildings shall be evacuated during any repair or alteration works unless the existing means of escape and fire protection system are continuously maintained or other exit and protection measures are taken to provide an equivalent degree of safety.
## 3.2 COMPONENTS OF MEANS OF ESCAPE
### 3.2.1
A means of escape shall be a continuous and unobstructed way of exit travel from any point in a building to a street, the roof of a building or a designated area of refuge. The path of travel along a means of escape may consist of three parts : (a) the exit access, (b) the exit, and (c) the exit discharge. That portion of the means of escape which leads to the entrance of an exit and is included in the measure of travel distance to reach an exit shall be termed the exit access. The exit itself shall be considered to be that portion of the means of escape which is protected from the area of incidence and provides a safe path to the exit discharge. The exit discharge shall comprise any portion of the travel between the termination of exit and the exterior or the area of refuge.
### 3.2.2
The parts of the means of escape may consist of any of the following exit components :
a) A doorway, corridor or passage leading to an exterior or interior staircase, smoke proof and fireproof enclosure, ramp, balcony, fire escape or combination thereof, having direct access to the street, the roof of a building or any designated refuge area which affords safety from fire or smoke from the area of incidence;
b) A horizontal exit from the affected building to an adjoining building or an area of refuge at the same level which provides safety from fire and smoke from the area of incidence and the areas communicating therewith.
### 3.2.3
Lifts, escalators and moving walks shall not be regarded as components of means of escape.
## 3.3 GENERAL REQUIREMENTS
### 3.3.1
All buildings constructed for human occupancy or storage shall be provided with adequate exit facilities to permit safe and quick unaided escape of the occupants in the event of fire or other emergency.
### 3.3.2
An exit shall at no time be used for any purpose that would interfere with its use as a means of escape.
### 3.3.3
Exits and exit access corridors shall not be used as supply or return air ducts.
### 3.3.4
Where changes in elevation not exceeding 300 mm exist in exits or exit access corridors, ramps shall be used. At exterior doors not required to be used by handicapped or aged people, a maximum step down of 200 mm shall be permitted.
All exits shall be clearly visible and exit access corridors and passages leading to the exit shall be marked and signposted to guide the occupancy traffic. Exit signs in pubic places used during the hours of darkness and those in areas required to have more than one exit or exit access shall be illuminated in accordance with the provisions of Sec 1.5 of Part 8.
### 3.3.5
The owner or lessee of all new and existing buildings shall be responsible for the safety of all occupants. If in any existing building, the exit facilities are deemed inadequate in view of the requirements of this Code, the Authority may order additional provisions to be incorporated in the building in order to minimize hazard to life of the occupants.
## 3.4 LOCATION AND ARRANGEMENT OF EXITS
### 3.4.1
All exits shall be easily discernible and accessible from the areas served by them.
### 3.4.2
Exit from any room or space shall not open into an adjoining or intervening room or area except where such adjoining room or area is an accessory to the area served, is not a hazardous occupancy and provide a direct escape to the designated exit area.
### 3.4.3
No portion of an exit route shall pass through a room that may be subject to locking or be intervened by a door that may be locked when the building is occupied.
### 3.4.4
All assembly buildings shall front on at least one street on which the main exit discharge shall be located. The main entrance to an assembly building shall also serve as the main exit capable of providing escape for at least one-half of the total occupant load. For assembly buildings having more than one levels or floors each level shall be provided with additional exits capable of providing escape for at least two-thirds of the occupant load served by that level.
### 3.4.5
All exits shall be so located and arranged that they provide continuous and unobstructed means of escape to the exterior of the building leading to a street or to other designated areas of refuge.
## 3.5 OCCUPANT LOAD
### 3.5.1 Design Occupant Load
The occupant load for which the exit facilities are to be provided shall be established by the largest number computed by the provisions of (a), (b) and (c) below :
a) The actual number of occupants for whom the area served by the exits is designed;
b) Number of occupants computed at the rate of one occupant per unit of floor area as prescribed in Table 4.3.1.
c) The number of occupants in any area as computed by the provisions of (a) or (b) above plus the number similarly computed for all spaces that discharge through this space in order to gain access to the exit.
### 3.5.2 Fixed Seats
The occupant load for an assembly or educational area having fixed seats shall be determined by the seating capacity of the area. For fixed seats without dividing arms, the capacity shall be taken as one person for every 500 mm of seat.
### 3.5.3 Maximum Occupant Load
The occupant load calculated as above need not exceed one person per 0.3 m² of usable floor space.
### 3.5.4 Mezzanine Floors
The occupant load of a mezzanine floor discharging through a floor below shall be added to the receiving floor's occupant load.
### 3.5.5 Roofs
Roofs used as assembly, educational or other areas of human occupancy shall be provided with exit facilities for the required occupant load.
## 3.6 CAPACITY OF EXIT COMPONENTS
The capacity of means of exit shall be adequate for the occupant load of the area served thereby. The required width of each exit component shall be computed on the basis of the exit width per occupant prescribed in Table 4.3.2, subject to the minimum width of each such component specified in Sec 3.7, 3.8, 3.9, 3.10, 3.11 and 3.12.
**Table 4.3.1 Occupant Load for Various Occupancies**
| Occupancy | Unit of Floor Area in m² per Occupant |
| :-------------------------------------------------------------------------------------------------------------------------------- | :------------------------------------------------------- |
| **A Residential** | 18 gross |
| **B Educational**
class room
preschool |
2 net (see also Sec 3.5)
3.5 net |
| **C Institutional** | 12 gross |
| **D Health Care**
In patient areas
Out-patient areas |
15 gross
10 gross |
| **E Assembly**
with fixed seats
without fixed seats
standing space only
with table and chairs |
See Sec 3.5
0.7 net
0.3 net
1.5 net |
| **F Business and Mercantile**
Office space
Shopping/sales area |
10 gross
3 gross |
| **G Industrial** | 10 gross |
| **H Storage** | 30 gross |
| **J Hazardous** | 10 gross |
**Table 4.3.2 Required Exit Width per Occupant**
| Occupancy | Buildings without Sprinkler System
(mm per person)
Stairways \| Ramps & Corridors \| Doors | Buildings thoroughly Sprinkled
(mm per person)
Stairways \| Ramps & Corridors \| Doors |
| :--------------------------------------------------------------------------------------------------------------------------------------------- | :--------------------------------------------------------------------------------------------------: | :----------------------------------------------------------------------------------------------: |
| **A Residential**
**B Educational**
**F1, F2 Business & Mercantile**
**F4 Mercantile**
**G Industrial**
**H Storage** | 8 5 4 | 5 4 4 |
| **C1, C2 Institutional** | 10 5 4 | 5 5 4 |
| **C3, C4 Institutional** | 8 5 4 | 8 5 4 |
| **D Health Care** | 25 18 10 | 15 12 10 |
| **E Assembly**
**F3 Business and Mercantile** | 10 7 5 | 7 5 5 |
| **J Hazardous** | 8 5 4 | 8 5 4 |
## 3.7 CORRIDORS AND PASSAGEWAYS
### 3.7.1
Direct route of access to required exits shall be provided through continuous passageways, corridors or aisles which are maintained free of obstructions. As far as practicable, occupants commencing exit travel at any point along the corridor or passageway shall be lead to an exit irrespective of their direction of travel. The length of a dead end in which no exit door is available shall not exceed 10 m.
### 3.7.2
The minimum required width of corridors and passageways shall be determined on the basis of the occupant load in accordance with the provisions of Sec 3.6, but it shall not be less than the most restrictive of the following :
a) 1.1 m where serving an occupant load of more than 50.
b) 0.9 m where serving an occupant load of 50 or less.
c) 2.4 m in Health Care buildings (Occupancy D) where movement of beds is necessary.
d) 1.8 m in Educational buildings (Occupancy B) where the occupant load is more than 150.
### 3.7.3
The width of exit corridors and passageways shall not be less than the aggregate of the required width of doors leading from them towards the exterior.
### 3.7.4
The minimum clear height of the corridors and passageways shall not be less than 2.4 m.
### 3.7.5
All exit access corridors shall have a fire resistance rating of 1 hour or more.
### 3.7.6
Door assemblies opening on to the exit access corridors shall be fire doors having a fire resistance rating of at least 20 minutes when tested in accordance with ASTM E152 without the hose stream test.
## 3.8 ASSEMBLY AISLES
### 3.8.1
Assembly buildings which contain seats, tables, equipment or displays shall be provided with aisles, free of obstructions, leading to the exit.
### 3.8.2
Exit access aisles may be level or ramped with slopes not exceeding 1 in 8. The clear width of level or ramped aisles shall be obtained at the rate of 5 mm per person, subject to the minimum specified in Sec 3.8.4.
### 3.8.3
When stepped aisles are provided the minimum tread depth shall be 275 mm. The required width per person shall be obtained from the following expressions, subject to the minimum specified in Sec 3.8.5.
For aisles with handrails,
$$
\text{width} = 7 + 0.04 (R - 175) \text{ mm per person;}
$$
For aisles without handrails,
$$
\text{width} = 9 + 0.04 (R - 175) \text{ mm per person;}
$$
in which $R = 175$, for rise up to 175 mm, and $R$ = the rise, for rise greater than 175 mm.
The rise shall not be less than 100 mm nor more than 200 mm.
### 3.8.4
The minimum width of level or ramped aisles shall be as specified below :
* Seats on both sides of the aisle: 1 m
* Seats on one side of the aisle: 0.9 m
### 3.8.5
The minimum width of stepped aisles shall be as specified below :
* Seats on both sides of the aisle: 1.2 m
* Seats on one side of the aisle: 1 m
### 3.8.6
The minimum clear gap between rows, measured as the clear horizontal distance between the back of the row ahead and the nearest projection of the row behind shall be 300 mm. For chairs having automatic or self-rising seats, the measurement shall be made with the seats in the raised position; for non-automatic seats the measurement shall be taken with the seats in the down position.
### 3.8.7
For rows of seats served by aisles or doorways at both ends, the number of seats per row shall not exceed 100. The minimum clear gap between rows shall be increased beyond 300 mm specified in Sec 3.8.6 by 7 mm for each seat in excess of 15, but the clear gap need not exceed 550 mm.
### 3.8.8
For rows of seating served by an aisle or doorway at only one end of the row, the path of travel shall not exceed 10 m from any seat to the aisle or doorway. The minimum clear gap between rows shall be increased beyond 300 mm specified in Sec 3.8.6 by 15 mm for each seat in excess of 7, but the clear gap need not exceed 550 mm.
## 3.9 DOORWAYS
### 3.9.1
Each occupant of a room or space shall have access to at least one exit or exit access door. The occupant load per exit door and the travel distance up to that door shall not exceed the values specified in Table 4.3.3.
### 3.9.2
Where either the occupant load or the travel distance exceeds the values specified in Table 4.3.3, at least two exit doors shall be provided.
### 3.9.3
The width of a doorway shall not be less than 1 m and the height not less than 2 m.
### 3.9.4
No sliding or hanging door shall be used as a means of exit.
### 3.9.5
All exit access doors shall be of a side-swinging type. When the occupant load exceeds 50, or in a hazardous occupancy, the doors shall swing outward from the room or in the direction of travel. Swinging of the door shall not constrict the width of the corridor below 0.9 m measured at the most critical position.
### 3.9.6
Exit doorways shall not open directly on a flight of stairs. A space of width not less than the width of the doorway shall be maintained immediately outside the doorway. The space shall be at the same level as that of the floor the door serves.
**Table 4.3.3 Maximum Occupant Load and Travel Distance for Spaces with One Exit Door**
| Occupancy | Maximum Occupant Load | Maximum Travel Distance (m) |
| :--------------------------------------------------------------------------- | :-------------------: | :-------------------------: |
| A Residential
C Institutional
D Health Care | 12 | 23 |
| B Educational
E Assembly
F Business & Mercantile
G Industrial | 50 | 23 |
| H Storage | 30 | 30 |
| J Hazardous | 5 | 8 |
### 3.9.7
Revolving doors shall not be used as a means of exit in assembly, educational or institutional buildings or in spaces with an occupant load of 200 or more. In all other cases revolving doors shall not constitute more than half of the total required exit door width. No power operated revolving door that cannot be operated manually in the event of power failure shall be permitted.
### 3.9.8
All exit doors shall be openable from the side they serve without the use of a key.
## 3.10 STAIRWAYS
### 3.10.1
The required width of exit stairways shall be computed in accordance with the provisions of Sec 3.6, but it shall not be less than the minimum widths specified in Table 4.3.4.
**Table 4.3.4 Minimum Widths of Exit Stairways**
| Occupancy | Minimum Width of Stairway (m) |
| :---------------------------------------------------------------------------------- | :---------------------------: |
| A Residential
A1, A2
A3, A4
A5 |
1.0
1.5
0.75 |
| B Educational
Occupant load up to 150
Occupant load more than 150 |
1.5
2.0 |
| E Assembly
E1, E3, E5
E2, E4 |
2.0
1.5 |
| All others | 1.5 |
### 3.10.2
The least dimension of landings and platforms in exit stairways shall not be less than the required width of stairway, except that the landing between two stair flights in a straight run shall not be required to be wider than 1.2 m in the direction of travel.
### 3.10.3
The rise and tread dimensions and the headroom requirements shall conform to the provisions Sec 1.12.5 of Part 3.
### 3.10.4
Spiral and winding stairways shall be permitted as an element of a means of escape only within a dwelling unit and from a mezzanine floor not more than 25 m² in area. The minimum width of all such stairways shall be 650 mm with each tread having a minimum depth of 200 mm at a distance of 300 mm from the narrower end. All treads shall be identical. The rise shall not be more than 225 mm with a permissible tolerance of 5 mm between adjacent risers and 10 mm between the largest and the smallest risers.
### 3.10.5
Stairways serving as means of escape shall have continuous guards and handrails on both sides. Where the width of the stair exceeds 2.2 m, intermediate handrails shall be provided so that no point on the stair is farther than 1 m from the handrails.
### 3.10.6
All exit stairways shall be constructed of materials that conform to the fire resistance requirements of the type of construction of the building, except that solid wooden handrails shall be permitted for all types of construction.
### 3.10.7
An exit stairway shall not be built around a lift shaft unless the enclosure of the lift shaft is solid and made of a material with fire resistance rating required for the type of construction of the building.
### 3.10.8
Exterior staircases used as fire escapes shall not be considered as a means of exit, unless they lead directly to the ground, are separated from the building interior by fire resistive assemblies or walls and are constructed of noncombustible materials.
## 3.11 RAMPS
### 3.11.1
The minimum width of exit ramps shall not be less than that required for corridors by Sec 3.7.
### 3.11.2
The slope of an exit ramp shall not exceed 1 in 8, but for slopes steeper than 1 in 10 the ramp shall be surfaced with approved non-slip material or finished such as to effectively prevent slipping.
### 3.11.3
Guards or handrails shall be provided on both sides of ramps having slope steeper than 1 in 15.
## 3.12 HORIZONTAL EXITS
### 3.12.1
The connection between an area of the building which the horizontal exit serves and the area of refuge or another building shall be provided with protected openings in 2 hour fire resistance rated walls, or by open air balcony or bridge.
### 3.12.2
The horizontal exit shall be protected from the area of incidence by self closing type fire door.
### 3.12.3
The width of a horizontal exit shall not be less than 1 m.
### 3.12.4
The slope of the horizontal exit shall not exceed 1 vertical in 10 horizontal. No steps shall be used in horizontal exits.
### 3.12.5
Where the horizontal exit serves as an exit from only one side, all doors shall swing in the direction of escape travel. Where exit from both sides may be required, the doors shall have two leaves opening in opposite directions, or there shall be adjacent doors opening in opposite directions. The doors shall be openable at all times when the building is occupied without the use of a key.
### 3.12.6
The discharge area of a horizontal exit shall be either public spaces or private to the occupants of the building. The capacity of the area of refuge or building on the refuge side shall be computed as the minimum net floor area excluding stairways, shafts etc. The required capacity of refuge shall be 0.28 m² per occupant. In the case of patients confined to bed in hospitals and clinics etc., the required capacity of refuge shall be 2.8 m² per bed.
## 3.13 SMOKE PROOF ENCLOSURES
### 3.13.1
A smoke proof enclosure shall consist of an interior stairway conforming to Sec 3.10 and an exterior balcony or a ventilated vestibule.
### 3.13.2
All exit stairways serving occupants located more than 23 m above the ground shall be protected by a smoke proof enclosure.
### 3.13.3
There shall be access to the stairways from every storey by way of a vestibule or an open balcony. The minimum width of a vestibule shall not be less than 1.1 m nor less than the width of the corridor leading to the vestibule. The minimum length of a vestibule in the direction of escape travel shall be 1.8 m.
### 3.13.4
The minimum fire resistance rating of the walls separating the smoke proof enclosure from the area of incidence shall be 4 hours with no openings other than the required fire doors for exit.
### 3.13.5
All doors in smoke proof enclosure shall be self closing type or they shall be fitted with automatic closing devices triggered by the fire detection system installed at the floor side entrance to the enclosure. The activation of fire detection system at any door in any floor shall activate the automatic door closers of all the doors at all levels of the smoke proof enclosure.
### 3.13.6
When access to the stairway is through a vestibule instead of an open exterior balcony, the vestibule shall have adequate natural ventilation. Each vestibule shall have a minimum area of opening of 1.5 m² in an exterior wall facing a courtyard, street or public way wider than 6 m.
## 3.14 NUMBER OF EXITS
### 3.14.1
The requirements of the number of exits specified in this subsection shall apply to buildings of all occupancy groups unless a more restrictive requirement for any occupancy is provided in Chapter 5, Part 4 or elsewhere in this Code.
### 3.14.2
Only one means of exit shall suffice for the buildings specified in Table 4.3.5 provided that they do not have more than one floor below the level of exit discharge.
### 3.14.3
For all other buildings the required number of exits shall depend on the occupant load as specified below:
* Occupant load 500 or less: Minimum 2 exits
* Occupant load 501 to 1000: Minimum 3 exits
* Occupant load more than 1000: Minimum 4 exits
**Table 4.3.5 Buildings Served by One Means of Exit**
| Occupancy | Maximum Number of Storeys | Other Restrictions |
| :-------- | :-----------------------: | :-------------------------------------------------------------- |
| All | 1 | Maximum occupant load 100 and maximum travel distance 25 m |
| A1 | 2 | Maximum occupant load 30 |
| A2 | 6 | Maximum 12 dwelling units |
| A3 | 4 | Maximum 50 occupants per floor and maximum travel distance 25 m |
| A4 | 6 | Maximum 50 occupants per floor and maximum travel distance 25 m |
| A5 | 2 | Maximum occupant load 50 |
| B, C | 2 | Maximum occupant load 200 |
| D | 2 | Maximum occupant load 50 |
| F, G, H | 2 | Maximum occupant load 100 and maximum travel distance 25 m |
### 3.14.4
All buildings more than 6 storeys or 20 m in height and all buildings having a floor area larger than 500 m² on each floor, used as educational, institutional, assembly, industrial, storage or hazardous occupancy or a mixed occupancy involving any of these, shall have a minimum of two staircases. The staircases shall be of the enclosed type and shall lead directly to the exterior or the designated area of refuge.
## 3.15 LENGTH OF TRAVEL
### 3.15.1
Exits shall be arranged in such a manner that the travel distance from any point in the area served shall not exceed the following values:
* Occupancy A, B, C, D, E, J: 25 m
* Occupancy F, H: 30 m
* Occupancy G: 45 m
### 3.15.2
Wherever more than one exit are required in a building they shall be placed as remote as possible from each other. As far as practicable, exits shall be arranged in such a manner as to provide refuge to a person irrespective of the direction of travel from any point in the area served.
## 3.16 MEANS OF EXIT SIGNS AND ILLUMINATION
### 3.16.1
All required means of exit or exit access in buildings or areas requiring more than one exit shall be signposted. The signs shall be clearly visible at all times, where necessary supplemented by directional signs. All exit doors shall be clearly marked for easy identification.
#### 3.16.1.1 Location
Exit signs shall be installed at stair enclosure doors, horizontal exits and other required exits from the storey. When two or more exits are required from a room or area, exit signs shall be installed at the required exits from the room or area and where otherwise necessary to clearly indicate the direction of escape.
**Exceptions:**
1. Main exterior exit doors which obviously and clearly are identifiable as exits need not be signed when approved by the Building Official.
2. Exit signs are not required for buildings of Occupancy A1 and individual units of A2.
3. No sign is needed for exits from rooms or areas with an occupant load of less than 50 when located within C1, C2 or C3 Occupancy.
#### 3.16.1.2 Graphics
The colour and design of lettering, arrows and other symbols on exit signs shall be in high contrast with their background. Words on the signs shall be at least 150 mm high with a stroke of not less than 20 mm.
#### 3.16.1.3 Illumination
Signs shall be internally or externally illuminated by two electric lamps or shall be of an approved self-luminous type. When the luminance on the face of an exit sign is from an external source, it shall have an intensity of not less than 5.0 foot-candles from either lamp. Internally illuminated signs shall provide equivalent luminance.
#### 3.16.1.4 Source of Power
Supply of power to one of the lamps for exit signs shall be provided by the premises’ wiring system. Power to the other lamp shall be from storage batteries or an on-site generator set and the system shall be installed in accordance with the provisions of Chapter 2, Part 8.
#### 3.16.1.5 Floor-level Exit Signs
For floor-level exit signs additional approved low-level exit signs which are externally or internally illuminated, or self-luminous, shall be provided in all interior exit corridors serving guest rooms of hotels in Occupancy A5. The bottom of the sign shall be less than 150 mm or more than 200 mm above the floor level. For exit doors, the sign shall be on the door or adjacent to the door with the closest edge of the sign within 100 mm of the door frame.
#### 3.16.1.6 Amusement Building Exit Marking
Approved exit direction marking and exit signs shall be provided. Approved low-level exit signs and directional marking shall be located not more than 200 mm above the walking surface and at the exit path.
### 3.16.2
All exit signs shall be illuminated at night, or during dark periods within the area served, in accordance with the provisions of Sec 1.5.1, Part 8.
### 3.16.3
The means of exit and exit access in buildings requiring more than one exit shall be equipped with artificial lighting. The lighting facilities shall satisfy the requirements of Sec 1.5.2, Part 8.
## 3.17 EXIT REQUIREMENTS FOR OCCUPANCY A: RESIDENTIAL
In addition to the general exit requirements specified in Sec 3.3 through 3.16 residential buildings shall satisfy the particular exit requirements specified in this section.
### 3.17.1 A1 Detached Single Family Dwelling
#### 3.17.1.1
Every sleeping room in a detached single family dwelling having more than two bedrooms shall have at least one exit door directly leading to the building's means of exit or the exterior. In addition, every sleeping room in the ground, first and second floors shall have an emergency escape route through an openable window or door in accordance with the requirements of Sec 2.5.3.2 of Part 3.
#### 3.17.1.2
Rooms having access to it only by removable ladder, folding stair or trap door shall not be used as a habitable room.
#### 3.17.1.3
All locking devices shall be prohibited should it impede or obstruct exit, such as chain type bolts, limited opening sliding type locks and burglar locks which do not disengage easily by quick-release catches. All closet door latches shall be such that all occupants including children can manipulate and open it from inside.
#### 3.17.1.4
Basement shall not be used to accommodate habitable rooms.
### 3.17.2 A2 Flats or Apartments
#### 3.17.2.1
All dwelling units of occupancy A2 shall comply with the exit requirements specified for occupancy A1.
#### 3.17.2.2
Basement of such buildings with floor level not more than 2.5 m below the formation level may house a heating plant, incinerator room or such other hazardous occupancy, provided that the access to the basement is only from the exterior of the building.
#### 3.17.2.3
At least half of the required exits shall discharge directly to the outside of the building.
### 3.17.3 A3 Mess, Boarding Houses, Dormitories and Hostels
The dwelling units of occupancy class A3 shall comply with the exit requirements specified under Sec 3.17.1 and 3.17.2 above.
### 3.17.4 Minimum Standard Housing
Provisions specified for occupancy A1 and A2, as detailed in Sec 3.17.1 and 3.17.2 above shall be complied with.
### 3.17.5 A5 Hotels and Lodging Houses
#### 3.17.5.1
All floors including the basement shall have access to at least two exit points located as remote as possible.
#### 3.17.5.2
The exits shall be linked with a common lobby or open area, so that the occupants may choose any of the two travel paths in case of emergency.
#### 3.17.5.3
Single exit shall be permitted where the rooms open directly to the street or a grade level and the travel distance from any point of the building to the exit is not more than 15 m.
#### 3.17.5.4
Habitable rooms in basements shall have at least two independent exits.
#### 3.17.5.5
Basements, which are not open to public and used for storage or as electro-mechanical room or for other service operation shall have exit appropriate for that particular use in accordance with the provisions of this Code.
## 3.18 EXIT REQUIREMENTS FOR OCCUPANCY B: EDUCATIONAL
In addition to the general exit requirements specified in Sec 3.3 through 3.16, educational buildings shall satisfy the following exit requirements.
### 3.18.1
There shall be at least two separate exits on every floor of the building and the exits shall be as far apart as possible.
### 3.18.2
There shall not be any dead end pockets in the circulation corridors and on the exit route.
### 3.18.3
Rooms having capacity of accommodating 100 persons shall have two doorway and such doorways shall provide access to separate exits or shall open to a passageway leading to separate exits in opposite direction.
### 3.18.4
The door locks of classroom shall be of simple type so that the occupants can operate the locks easily during emergency.
## 3.19 EXIT REQUIREMENT FOR OCCUPANCY C: INSTITUTIONAL
In addition to the provisions set forth in Sec 3.3 through 3.16, institutional buildings shall satisfy the following exit requirements.
### 3.19.1
At least two exits shall be provided for every floor. The exits may be of one or more of the following types:
a) Doors leading directly outside the building
b) Stairways
c) Ramps
d) Horizontal exits
### 3.19.2
Revolving doors shall not be considered as an exit.
### 3.19.3
The exits of custodial and penal and mental institutions shall have a minimum clear width of 1.5 m and the corridors serving the inmates shall have a minimum width of 2.4 m.
### 3.19.4
The elevators and lifts shall not be counted as exits.
### 3.19.5
The fire doors and smoke barriers shall be kept open during normal operation but shall close automatically during emergency. Provisions of manual closing of fire or smoke door during emergency shall be provided.
### 3.19.6
Reliable means shall be provided to permit prompt release of inmates from any locked section in case of fire or other emergency. Adequate number of guards and other personnel shall be continuously on duty to evacuate the inmates from penal and mental institutions during emergency.
## 3.20 EXIT REQUIREMENTS FOR OCCUPANCY D: HEALTH CARE
In addition to the provisions set forth in Sec 3.3 through 3.16, health care facilities shall satisfy the requirements as detailed in Sec 3.19 above.
## 3.21 EXIT REQUIREMENTS FOR OCCUPANCY E: ASSEMBLY
In addition to the general requirements specified in Sec 3.3 through 3.16, assembly buildings shall satisfy the particular exit requirements specified in this section.
### 3.21.1
Large assembly buildings with fixed seats (Occupancy E1) shall have at least four separate exits located as remote from each other as possible.
### 3.21.2
Small assembly buildings with fixed seats (Occupancy E2) shall have at least two separate exits located as remote as possible from each other. If the capacity of assembly exceeds 600 persons, at least three exits shall be provided.
### 3.21.3
Assemblies of Occupancy E3, E4 and E5 shall have at least two means of exits leading directly to the street or leading to a corridor or open space having access to exits in two independent and different direction.
### 3.21.4
For fixed seat assemblies, clear width of aisles shall not be less than 1.2 m and no seats shall be seven seats away from the aisles. Cross-aisles for every 10 rows of seating shall be provided to facilitate direct access to the exit. Steps shall not be provided in aisles, unless the gradient exceeds 1 in 10.
### 3.21.5
Balconies, galleries, fascia of boxes shall be provided with railings not less than 650 mm high above the floor.
### 3.21.6
No turnstile or other devices to restrict the movements of persons shall be installed in assembly areas.
### 3.21.7
In theatres and similar places, the waiting lobby shall be designed in such a way that it does not encroach the required width of exit. The exits of theatres, auditorium etc. shall be designed in such a way that these may serve the people inside the theatre or auditorium and the people waiting in the lobby simultaneously at the time of emergency.
### 3.21.8
Display of exit signs shall be placed in such a way that it does not interfere with the access of any exit. No mirror shall be placed adjacent to exit way as it may confuse the direction of exits.
### 3.21.9
The interior finish of lobby, exit corridor and exit shall be of a noncombustible material.
## 3.22 EXIT REQUIREMENTS FOR OCCUPANCY F: BUSINESS AND MERCANTILE
In addition to the general requirements as specified in Sec 3.3 through 3.16, business and mercantile buildings shall meet the requirements of this section.
### 3.22.1
At least two exits shall be provided for every floor including the basement of a business and mercantile building.
### 3.22.2
The occupancy of mezzanine floor, balconies, open floor space etc., which are linked with the main business or mercantile building shall be taken into consideration for determining the exit requirements.
## 3.23 EXIT REQUIREMENTS FOR OCCUPANCY G: INDUSTRIAL
In addition to the provisions specified in Sec 3.3 through 3.16, industrial buildings shall meet the requirements specified in this section.
### 3.23.1
At least two exits shall be provided for each floor including basement of an industrial building.
### 3.23.2
For very large industrial buildings like aircraft assembly hanger, jute and textile mills etc., additional means of exit shall be provided so that the travel distance from any work area to exit point does not exceed 30 m.
## 3.24 EXIT REQUIREMENTS FOR OCCUPANCY H: STORAGE
In addition to the general requirements as specified in Sec 3.3 through 3.16, storage facilities shall satisfy the requirements detailed in this section.
### 3.24.1
All structures which are used as storage and have more than 1400 m² of floor area or where more than 10 persons are normally present shall have at least two separate means of exit.
### 3.24.2
During operational hours, the door locks of a storage building shall be kept in such a way that these can be unlocked easily during a fire or emergency.
### 3.24.3
The parking garages shall have at least two separate means of exit.
### 3.24.4
Exits from aircraft hangers shall be provided at intervals of not more than 45 m on all exterior walls and there shall be a minimum of two exits for each aircraft storage or servicing area.
### 3.24.5
For grain or other silos, there shall be at least one dust proof, noncombustible tower connecting all the floors. Self closing noncombustible door shall have to be provided at each floor landing.
### 3.24.6
An exterior basket type ladder shall be provided form the roof of workhouse to ground level.
## 3.25 EXIT REQUIREMENTS FOR OCCUPANCY J: HAZARDOUS
The exit requirements for hazardous occupancy shall be those specified in Sec 3.3 through 3.16. Exits in such occupancy shall also meet the requirements of Sec 3.23.
# Chapter 4: Equipment and In-built Facilities
Source: https://docs.sayed.app/bnbc2006/part-4-fire-protection/chapter-4-equipment-and-in-built-facilities
## 4.1 SCOPE
The provisions of this chapter shall control the design, installation and management of equipment and in-built facilities for fire fighting within a building and its premises. The regulations of this chapter shall be applicable for all buildings (whether the system will be required by the Code or by owner's request) and the provisions stated herein shall not cover the fire fighting requirements outside the building premises.
## 4.2 FIRE PROTECTION PLUMBING
### 4.2.1 Water Requirement for Interior Fire Protection
The minimum quantity of water for sprinkler and hose use within the building according to their occupancy classification shall be in accordance with Table 4.4.1 or on the basis of the hydraulic design of the system.
**Table 4.4.1: Fire Protection Flow Requirements**
| Building Type | Sprinkler System (l/min.)\* | Standpipe and hose System (l/min.)\* | Duration\*\* (minute, min.) |
| --------------------- | --------------------------- | ------------------------------------ | --------------------------- |
| Light hazard - I | 1000 | 1000 | 30 |
| Light hazard - II | 1900 | 1900 | 50 |
| Ordinary hazard - I | 2650 | 1900 | 75 |
| Ordinary hazard - II | 3200 | 1900 | 75 |
| Ordinary hazard - III | 4800 | 1900 | 75 |
*Notes:*
*\* Values will be for one riser serving floor area of 1000 m².*
*\*\* These durations shall be for a building up to the height of 51 m. For greater height of 51-102 m and above 102 m, the duration will be 1.25 times and 1.5 times of the specified values respectively.*
*Light hazard - I : Occupancy groups, A1, A2, A4*
*Light hazard - II : Occupancy groups, A3, A6, A7, A8, B, C, D, E2, E4, E7, F1 & F2*
*Ordinary hazard - I : Occupancy groups, E1, E3, E5, F3, F4, F5, F6, F7, G1 & G4*
*Ordinary hazard - II : Occupancy groups, G2 & H1*
*Ordinary hazard - III : Occupancy groups, G3 & H2*
*Extra hazard : Occupancy group J - pressure and flow requirement for this group shall be determined by Fire Department but shall not be less than required value for Ordinary hazard - III*
### 4.2.2 Water Sources for Fire Protection
Water required for interior fire protection of a building shall be supplied from one or a combination of the following sources.
#### 4.2.2.1 Direct Connection to Water Main
For continuous water supply (public water supply system or independent system only for fire protection) with sufficient quantity and pressure to feed fire fighting equipments during peak demand period, direct connection of fire fighting system to the water main may be adopted (Fig 4.4.1).
#### 4.2.2.2 Roof Gravity Tanks
For water supply system with sufficient quantity of water during peak demand period but with insufficient pressure to roof tank, a roof gravity tank shall be provided to feed fire fighting equipments (Fig 4.4.2).
#### 4.2.2.3 Storage Tank
For water supply system with inadequate pressure to feed fire fighting equipments or roof gravity tank, the building premises shall have a ground (or underground) tank to store water for fire fighting and one of the combinations shown in Fig 4.4.3, 4.4.4 and 4.4.5 shall be adopted.
The system only for fire fighting purpose may be designed with automatic fire pump as shown in Fig 4.4.3.
The water supply system for domestic use and fire service may be designed with roof gravity tank and manually controlled pump as shown in Fig 4.4.4. The pressure tank with automatic fire pump and compressor may be used for supplying water to the fire fighting equipments as shown in Fig 4.4.5 and 4.4.6.
The location of pressure tank shall be such that it will provide the required pressure at the highest fire fighting equipment.
The water stored in storage tank for fire fighting operation shall not be used for other purposes (see Fig 4.4.7).
The ground storage tank shall be easily accessible to fire engine of Fire Department. In absence of space available for fire engine, the cover slab of ground storage tank shall be designed to withstand a vehicular load of local fire engine.
### 4.2.2.4 Individual Water Sources
In absence of public water supply system, the building premises shall have individual water sources specified in Sec 6.19 of Part 8. The individual water sources with adequate yield during peak demand period will serve as a fire service ground tank as shown in Fig 4.4.3, 4.4.4 and 4.4.5. Otherwise, the water from the individual sources shall have to be stored in a storage tank specified in Sec 4.2.2.3.
### 4.2.3 Design Considerations for Standpipe and Hose System
#### 4.2.3.1
The fire protection system shall be designed for their effective use either by amateur or trained fire fighting personnel or both.
#### 4.2.3.2
All standpipes in standpipe system shall be sized so that they will provide a minimum flow specified in Table 4.4.1. In standpipe system with more than one standpipe, the supply piping shall be sized for the minimum flow specified in Table 4.4.1 for the first standpipe plus 1000 litre per minute for each additional standpipe. The total number of such additional standpipes shall not be more than 8. All standpipe risers shall be connected through a gate valve with a main of size equal to that of the largest riser.
#### 4.2.3.3
The minimum pressure for standpipes supplying a 50 mm or larger hose shall be at least 300 kPa. For standpipe supplying first aid hose (38 mm nominal) may have a minimum pressure of 200 kPa.
#### 4.2.3.4
The size (diameter) of standpipes for various building height may be as shown in Table 4.4.2 or hydraulically designed to provide the required flow (Sec 4.2.3.2) and pressure (Sec 4.2.3.3) at the topmost outlet.
#### 4.2.3.5
The water supply required for combined system (for partial automatic sprinkler and Fire Department hose) shall be calculated in accordance with Sec 4.2.3.2 plus an amount equal to the hydraulically calculated sprinkler demand or 550 litre per minute for light hazard occupancy groups or 1900 litre per minute for ordinary hazard occupancy groups.
#### 4.2.3.6
The size of combined system shall be at least 150 mm or hydraulically designed to provide the required flow (Sec 4.2.3.5) and pressure.
#### 4.2.3.7
The standpipe shall be located in noncombustible enclosure such that it will be able to provide hose stream to the most remote area of the floor served.
**Table 4.4.2: Standpipe Sizes**
| No. of Storeys | Building Height (m) | Size of Standpipe (mm) |
| -------------- | ------------------- | ---------------------- |
| Up to 5 | Up to 17 | 75\* |
| Up to 10 | Up to 33 | 100 |
| 10 to 20 | 33 to 63 | 150 |
| 20 to 54 | 63 to 165 | 200 |
*\* Note: This size may be used only for occupancy groups A1, A2 and A4.*
#### 4.2.3.8
The hose shall be connected to the standpipe within 1.5 m from the floor. Hose stations shall be easily accessible for inspection and testing.
#### 4.2.3.9
The hose connection to a standpipe for large stream shall be at least 100 mm nominal and that of small stream may be 63 mm or 50 mm on each floor. The size of first aid hose shall be 38 mm nominal. The hose length shall not be more than 30 m.
#### 4.2.3.10
The static pressure in standpipe shall not exceed 650 kPa at hose outlet. Where pressure reducing valves are used, the design of pressure reducing valve shall be so that the pressure with the flowing stream shall not exceed 650 kPa.
#### 4.2.3.11
Different piping materials and fittings for standpipe system presented in Tables 4.4.3 and 4.4.4 shall conform to the standard or one of the standards cited against them. The standard requirements for other materials not provided in these tables shall be subject to the approval of the Authority.
#### 4.2.3.12
The standpipe riser shall be supported at the top and at the lowest level. The riser shall also be provided with support at the alternate level in between top and bottom level of the pipe riser. The support shall be of adequate strength to support the water-filled pipe load and an additional load of 110 kg.
The horizontal standpipe shall have hangers with a spacing not more than 5 m. The hanger shall be able to carry a load of five times the weight of the water-filled pipe and an additional load of 110 kg.
**Table 4.4.3: Piping for Standpipe System**
| Material | Standard |
| ---------------------------- | ------------------------------ |
| Copper Tube | ASTM B75, ASTM B88 |
| Copper and Copper-Alloy Tube | ASTM B251 |
| Steel Pipe | ASTM A53, ASTM A120, ASTM A135 |
| Wrought Steel or Iron | ANSI B36.10 |
**Table 4.4.4: Standpipe Fittings**
| Material | Standard |
| -------------- | ----------------------------------------------------------- |
| Cast Iron | ANSI B16.1, ANSI B16.4 |
| Copper | ANSI B16.18, ANSI B16.22 |
| Malleable Iron | ANSI B16.3 |
| Steel | ANSI B16.5, ANSI B16.9, ANSI B16.11, ANSI B16.25, ASTM A234 |
#### 4.2.3.13
There shall be Siamese connection to the standpipe system or to the delivery pipe of the gravity roof storage tank. The Siamese connection shall be easily accessible to fire engine.
#### 4.2.3.14
The system shall be provided with adequate drainage piping to discharge under pressure. The drain pipe shall not discharge into sanitary sewer.
#### 4.2.3.15
All control valves shall be designed to withstand the pressure specified in Sec 4.2.7.2a.
### 4.2.4 Design Consideration for Sprinkler System
#### 4.2.4.1
The pipe schedule sizing to supply different number of sprinklers for their different uses may be in accordance with Tables 4.4.5 and 4.4.6.
#### 4.2.4.2
Each sprinkler shall serve a maximum ceiling area specified in Table 4.4.7 for different types of building according to their uses.
#### 4.2.4.3
The recommended pressure for sprinkler system will be 100 kPa. The location of gravity storage tank to serve sprinkler system shall be at least 10 m above the top most line of sprinklers.
#### 4.2.4.4
Water supply pipings and fittings for sprinkler system shall conform to the standard or one of the standards cited against them in accordance with Tables 4.4.4 and 4.4.8. The standard requirements for other pipe materials not provided in these tables shall be subject to the approval of the Authority.
#### 4.2.4.5
The sprinkler system shall be provided with adequate support or made flexible to prevent pipe breakage during earthquake.
#### 4.2.4.6
The hanger in sprinkler system shall be designed to carry a load equal to five times the weight of the water-filled pipe plus an addition load of 110 kg.
The support shall be designed to support a load equal to the weight-filled pipe plus an additional load of 110 kg.
**Table 4.4.5: Size of Water Supply Steel Pipe to Sprinklers**
| Pipe Size mm (inch) nominal | No. of Sprinkler Connection for Light Hazard\* | No. of Sprinkler Connection Ordinary Hazard\* | No. of Sprinkler Connection Extra Hazard\* |
| --------------------------- | ---------------------------------------------- | --------------------------------------------- | ------------------------------------------ |
| 25 (1) | 2 | 2 | 1 |
| 32 (1¼) | 3 | 3 | 2 |
| 38 (1½) | 5 | 5 | 5 |
| 50 (2) | 10 | 10 | 8 |
| 63 (2½) | 30 | 20 | 15 |
| 75 (3) | 60 | 40 | 27 |
| 88 (3½) | 100 | 65 | 40 |
| 100 (4) | NL\*\* | 100 | 55 |
| 125 (5) | - | 160 | 90 |
| 150 (6) | - | 275 | 150 |
| 200 (8) | - | 400\*\*\* | 225\*\*\* |
*\* Definition of these terms are given in Table 4.4.1.*
*\*\* No limit.*
*\*\*\* One sprinkler system riser or combined system riser shall serve the floor area not more than 4850 m² for light and ordinary hazardous occupancy and 2325 m² for extra hazardous occupancy.*
**Table 4.4.6: Size of Water Supply Copper Pipe to Sprinklers**
| Pipe Size mm (inch) nominal | No. of Sprinkler Connection for Light Hazard\* | No. of Sprinkler Connection Ordinary Hazard\* | No. of Sprinkler Connection Extra Hazard\* |
| --------------------------- | ---------------------------------------------- | --------------------------------------------- | ------------------------------------------ |
| 25 (1) | 2 | 2 | 1 |
| 32 (1¼) | 3 | 3 | 2 |
| 38 (1½) | 5 | 5 | 5 |
| 50 (2) | 12 | 12 | 8 |
| 63 (2½) | 40 | 25 | 20 |
| 75 (3) | 65 | 45 | 30 |
| 88 (3½) | 115 | 75 | 45 |
| 100 (4) | NL\*\* | 115 | 65 |
| 125 (5) | - | 180 | 100 |
| 150 (6) | - | 300 | 170 |
| 200 (8) | - | \*\*\* | \*\*\* |
*\* Definition of these terms are given in Table 4.4.1.*
*\*\* No limit.*
*\*\*\* One sprinkler system riser or combined system riser shall serve the floor area not more than 4850 m² for light and ordinary hazard occupancy and 2325 m² for extra hazard occupancy.*
**Table 4.4.7: Ceiling Area for a Sprinkler**
| Building Type | Light Hazard\*\* Area, m² | Ordinary Hazard\*\* Area, m² | Extra Hazard\*\* Area, m² |
| ----------------------------------------- | ------------------------- | ---------------------------- | ------------------------- |
| Roof or Floor on Trusses, Girders or Beam | 20 (4.5\*) | 12 (4.5\*) | 8.4 (3.5\*) |
| With High Piling\*\*\* | - | 9.3 (3.5\*) | 8.4 (3.5\*) |
| Open Wood Joists | 12 (4.5\*) | 12 (4.5\*) | 8.4 (3.5\*) |
| With High Piling\*\*\* | - | 9.3 (3.5\*) | 8.4 (3.5\*) |
| Other Type of Construction | 15.6 (4.5\*) | 12 (4.5\*) | 8.4 (3.5\*) |
| With High Piling\*\*\* | - | 9.3 (3.5\*) | 8.4 (3.5\*) |
*Notes:*
*\* Maximum distance in m between sprinklers and between line of piping.*
*\*\* The definitions of these terms are given in Table 4.4.1.*
*\*\*\* Storage facilities which permit closely piled materials over 4.5 m or materials on rack over 3.6 m.*
**Table 4.4.8: Piping for Sprinkler System**
| Material | Standard |
| ----------------------- | ------------------------------------------------------ |
| Copper and Copper-Alloy | ASTM B32, ASTM B75, ASTM B88, ASTM B251 |
| Steel | ANSI B36.10, ASTM A53, ASTM A120, ASTM A135, ASTM A795 |
#### 4.2.4.7
There shall be Siamese connection to the sprinkler system located outside the building and accessible to the Fire Department connection.
#### 4.2.4.8
All risers shall be connected through a gate valve with a main of size equal to that largest riser.
#### 4.2.4.9
The sprinkler system shall be provided with adequate drainage arrangement. The drain pipe shall not discharge into sanitary sewer.
#### 4.2.4.10
All control valves and fittings shall be able to withstand the pressure specified in 4.2.7.2b.
### 4.2.5 Water Supply for Fire Protection in Tall Building
The quantity, sources and mode of water supply in tall building shall be in accordance with Sec 4.2.1 and 4.2.2. In tall buildings fittings and equipments for fire fighting may be subject to excessive pressure. Pressure on fire fighting equipments (Sec 4.2.3.10) in tall building shall be reduced by one or a combination of the following methods:
a) **Water Supply Zones with Automatic Fire Pump:** The building shall be divided into different water supply zones so that the fire fighting equipment will serve within their maximum allowable limit of pressure (Fig 4.4.8). Separate automatic fire pump or combination of pressure tank and automatic pump shall be installed for supplying water to the fire fighting equipments in each zone.
b) **Water Supply Zones with Intermediate Gravity Tank:** The building shall be divided into different water supply zones in accordance with 4.2.5a. Each water supply zones shall be provided with separate gravity overhead tank and manually operated pump (Fig 4.4.9). The fire fighting equipments in each water supply zone shall be supplied with water from their respective overhead gravity tanks.
c) **Using Pressure Reducing Device:** The water required by fire fighting equipments shall be supplied from roof gravity tank (Fig 4.4.10). Pressure on different fire fighting equipments shall be reduced by using pressure reducing valves (Fig 4.4.10).
### 4.2.6 Fire Pump
The fire pump shall be so designed that it shall satisfy the required pressures and flow for fire fighting equipments at the highest and most remote part of the protected premises during their peak demand hour or for pressure tank or for roof storage tank. The pump shall be housed in a readily accessible position in a building of non combustible construction. The pump shall be adequately protected against mechanical damage.
A manually controlled pump may be used to feed water into gravity overhead tank with fire reserve. There shall be provision for standby fire pump driven by a compression ignition (diesel) engine or electric pump with own generator.
The fire fighting equipments directly fed by fire pump shall be designed with automatic fire pump. Once the pump starts it shall run continuously until stopped manually. The pump shall be fully operational within 30 seconds after starting. There shall be provision for manual starting. The pump shall be compression ignition type or electricity driven with own generator. Where priming is necessary, automatic priming equipment shall be provided to ensure priming with water at all times. The fire pump shall not be used for other purpose.
### 4.2.7 Inspection, Testing and Maintenance
#### 4.2.7.1 Inspection
All pipings and equipments shall be inspected for satisfactory supports (in accordance with Sec 6.13 in Part 8 of this Code) and protection from damage and corrosion. All outlets shall be free from obstruction.
#### 4.2.7.2 Testing
Fire protection plumbing system or part thereof shall be tested and approved after installation by the Authority.
a) **Testing of Standpipe System:** The system shall be tested for a pressure 25% in excess of the highest working pressure for at least 2 hours. The system shall be able to maintain above test pressures. The system shall be also be tested for the required flow at the highest outlet.
b) **Testing of Sprinkler System:** This system shall be tested for at least 2 hours for a pressure of 1000 kPa or at 350 kPa in excess of normal working pressure when normal working pressure will be more than 650 kPa. The system shall be able to maintain above test pressures. The system shall also be tested for the required flow at the highest outlet.
c) **Testing of Pump:** The pump used for fire fighting purposes shall be tested for their performance characteristics. The pump shall be restored or repaired to its original condition if their performance characteristics fall below more than 10 per cent of the supplier's test characteristic curve or as specified for the fire protection water supply system.
#### 4.2.7.3 Maintenance
The system shall be maintained for safe operating conditions and tested at least once a year.
## 4.3 FIRE PROTECTIVE SIGNALLING OR FIRE ALARM SYSTEM
Fire protective signalling or fire alarm system, where required by the Code, shall specify plans and clearly delineate the locations and number of all alarm-initiating devices and alarm-indicating appliances. The plan shall also provide details of all equipment to be used, proposed zoning, list of auxiliary control functions, location of the control panel and enunciators and a complete sequence of operation for the system.
Fire protective signalling or fire alarm system, wherever required and installed shall be maintained in full operating condition.
## 4.4 AUTOMATIC FIRE AND SMOKE DETECTION SYSTEM
The installation of automatic fire and smoke detection system shall be a necessity when the size, arrangement and occupancy of a building become such that a fire itself can not provide adequate warning to its occupants.
The automatic fire and smoke detection system shall include, spot or line type heat sensitive detectors and optical, ionized or chemical sensitive type of smoke detectors. A guideline for selection and siting of fire detection system is provided in Appendix C.
## 4.5 FOAM EXTINGUISHING SYSTEM
### 4.5.1 General
Foam extinguishing system shall be of an approved type and shall be installed in accordance with the provisions of this Code. The foam extinguishing system is designed to discharge fire suppressive foam concentrates over the area to be protected.
#### 4.5.1.1
A foam extinguishing system shall be automatically actuated during a fire with provision of manual actuation.
#### 4.5.1.2
Warning sign and discharge alarm system shall be provided with the foam extinguishing system, which shall be actuated during the use of the system.
#### 4.5.1.3
The system shall be provided for protection of boiler rooms with its ancillary storage of furnace oils in basement and other areas where hazardous liquids are stored.
## 4.6 CARBON DIOXIDE EXTINGUISHING SYSTEM
### 4.6.1 General
Carbon dioxide extinguishing system shall be of an approved type and shall be installed as per provisions of this Code. The system supplies CO2 from a pressurized vessel through fixed pipes and nozzles.
#### 4.6.1.1
The system is used where water or foam cannot be used for fire extinguishing because of the special nature of the contents within the building or areas to be protected.
#### 4.6.1.2
The system shall be automatically actuated and shall be equipped with manual actuation devices as well.
#### 4.6.1.3
Warning signs and discharge alarm shall be provided where persons are likely to be trapped in an area made hazardous by carbon dioxide discharge.
## 4.7 HALOGENATED EXTINGUISHING SYSTEM
### 4.7.1 General
Halogenated extinguishing system shall be of an approved type and shall be installed in accordance with the provisions of this Code. The system comprise pipes, nozzles and halogenated chemical container under pressure.
#### 4.7.1.1
When carbon dioxide extinguishing systems are not proved suitable for special fire risk zones, halogenated extinguishing system shall be installed. The system shall be automatically actuated during a fire and shall be equipped with manual actuation devices as well.
#### 4.7.1.2
Warning sign and discharge alarm shall be provided where persons are likely to be trapped in an area made hazardous by halogenated hydrocarbons.
## 4.8 DRY CHEMICAL EXTINGUISHING SYSTEM
### 4.8.1 General
Dry chemical extinguishing system shall be of an approved type and shall be installed in accordance with the provisions of this Code and manufacture's instruction.
#### 4.8.1.1
The system shall be automatically actuated during a fire and shall be equipped with manual actuation device as well.
#### 4.8.1.2
Warning signs and discharge alarm shall be provided where persons are likely to be exposed to dry chemical discharge.
#### 4.8.1.3
The dry chemical agent of the system shall be nontoxic.
## 4.9 WET CHEMICAL EXTINGUISHING SYSTEM
### 4.9.1 General
A wet chemical system is a solution of water and potassium carbonate or acetate based chemical which forms the extinguishing agent. The system shall be installed in accordance with the provisions of this Code and manufacturer's installation instruction.
#### 4.9.1.1
The system shall be automatically actuated during a fire and shall be equipped with manual actuation device as well.
#### 4.9.1.2
In case of wet chemical range hood extinguishing system, label of an approved agent shall be affixed to the system.
#### 4.9.1.3
Warning signs and discharge alarm shall be provided where persons are likely to be exposed to wet chemical discharge.
## 4.10 PORTABLE FIRE EXTINGUISHER
### 4.10.1 General
Portable fire extinguisher shall be of an approved type and shall be installed as per manufacturer's instruction.
#### 4.10.1.1
Portable fire extinguisher shall be installed in private and public buildings as per specification and requirements of BDS 825 : 1991 (BDS 825 : 91).
#### 4.10.1.2
The portable extinguisher shall be placed near the path of exit travel and it shall be easily accessible.
#### 4.10.1.3
Fire hazard areas of a building like kitchen, public area, storage, electrical distribution point etc. shall be installed with portable fire extinguishers.
***
**Related Appendix**
Appendix C Detailed Guidelines for Selection and Siting of Fire Detection System
# Chapter 5: Specific Requirements for Various Occupancies
Source: https://docs.sayed.app/bnbc2006/part-4-fire-protection/chapter-5-specific-requirements-for-various-occupancies
## 5.1 SCOPE
The provisions of this chapter shall control the installation of fire detection and fixed fire fighting arrangement in low rise buildings of different occupancy groups. The term ‘Lowrise Building’ shall include all structures which are not taller than 20 m from the finished ground level and do not have more than six floors.
The fire detection and fire fighting arrangement required for highrise buildings are specified in Appendix D.
## 5.2 OCCUPANCY A: RESIDENTIAL
In addition to the general provisions covered under Chapter 4, the following requirements for lowrise buildings shall be complied with.
### 5.2.1 Occupancy A1: Detached Single Family Dwelling
Fire detection and fixed fire fighting arrangements shall not be required.
### 5.2.2 Occupancy A2: Flats and Apartments
Fire detection and fixed fire fighting arrangements shall not be required.
### 5.2.3 Occupancy A3: Mess, Boarding House and Hostels
For buildings upto 2 storey height, fire detection and fixed fire fighting arrangements shall not be required. Buildings having 3 floors or above and having floor area less than 300m² shall not require fire detection and fixed fire fighting arrangements. But if the floor area of such building is more than 300m² per floor and has central corridor with rooms on both sides, manually operated electric fire alarm system shall be provided along with portable fire extinguishers.
### 5.2.4 Occupancy A4: Minimum Standard Housing
Fire detection and fixed fire fighting arrangements shall not be required.
### 5.2.5 Occupancy A5: Hotels and Lodging Houses
For building upto 2 storey height, fire detection and fixed fire fighting arrangements shall not be required. Buildings having more than 2 floors or having an area of more than 300m² per floor, shall be provided with manually operated electric fire alarm system. Portable fire fighting appliances shall be kept as per instruction of the authority.
## 5.3 OCCUPANCY B: EDUCATIONAL
In addition to the general provisions specified in Chapter 4, the following requirements for Occupancy B shall be complied with.
### 5.3.1
Educational buildings upto 2 storey height and having less than 100m² floor area per floor shall not require fixed fire detection and fire fighting arrangements.
### 5.3.2
Educational buildings having more than 2 storey shall be provided with manually operated electric fire alarm system.
### 5.3.3
Portable fire fighting appliances shall be kept as per instruction of the concerned authority.
## 5.4 OCCUPANCY C: INSTITUTIONAL
The following provisions shall be complied with for lowrise institutional buildings.
### 5.4.1 Occupancy C1: Institution for Care of Children
Fire detection and fixed fire fighting arrangements shall not be required. Portable fire fighting appliances shall be kept as per instruction of the concerned authority.
### 5.4.2 Occupancy C2: Custodial Institution for the Physically Capable
Fire detection and fixed fire fighting arrangements shall not be required. Portable fire fighting appliances shall be kept as per instruction of the concerned authority.
### 5.4.3 Occupancy C3: Custodial Institution for the Physically Incapable
Manually operated electric fire alarm system shall be installed. Portable fire fighting appliances shall be kept as per instruction of the concerned authority.
## 5.5 OCCUPANCY D: HEALTH CARE FACILITIES
In addition to the general provisions, as detailed under Chapter 4, the following requirements shall be complied with.
### 5.5.1 Occupancy D1: Normal Medical Facilities
Manually operated electric fire alarm system and/or automatic fire alarm system shall be installed in the duty room, so that the duty personnel receive the fire warning well in advance. Requirements of manual or automatic fire alarm system or both shall be decided and approved by the appropriate authority. Portable fire fighting appliances shall be kept as per instruction of the concerned authority.
### 5.5.2 Occupancy D2: Emergency Medical Facilities
The requirements shall include the installation of manually operated electric fire alarm system and/or automatic fire alarm system as per Sec 5.5.1 above. Portable fire fighting appliances shall be kept as per instruction of the concerned authority.
## 5.6 OCCUPANCY E: ASSEMBLY
The special requirements for Occupancy E shall include the following.
### 5.6.1 Occupancy E1: Large Assembly with Fixed Seats
All auditorium, corridor, green rooms and canteen attached to assembly buildings shall be fitted with automatic fire alarm system and the performing stage shall preferably be covered by an automatic sprinkler system. Portable fire fighting appliances shall be kept as per instruction of the concerned authority.
### 5.6.2 Occupancy E2: Small Assembly with Fixed Seats
Shall comply with the requirements laid down in Sec 5.6.1 above.
### 5.6.3 Occupancy E3: Large Assembly without Fixed Seats
Automatic fire alarm system shall be provided. Portable fire fighting appliances shall be kept as per instruction of the concerned authority.
### 5.6.4 Occupancy E4: Small Assembly without Fixed Seats
Requirements specified in Sec 5.6.3 shall be complied with.
### 5.6.5 Occupancy E5: Sports Facilities
Manually operated electric fire alarm system shall be provided. Portable fire fighting appliances shall be kept as per instruction of the concerned authority.
## 5.7 OCCUPANCY F: BUSINESS AND MERCANTILE
In addition to the general provisions covered under Chapter 4, the following requirements for Occupancy F shall be complied with.
### 5.7.1 Occupancy F1: Offices
i) Office buildings less than 2 storey high and 500 m² floor area: No provision required except portable fire extinguishers.
ii) Office buildings more than 2 storey high or floor area more than 500m²: Manually operated electric fire alarm system shall be provided along with portable fire extinguishers.
iii) Other mercantile buildings more than 2 storey high and more than 500m² in floor area: Automatic fire alarm system required along with portable fire extinguishers.
iv) Laboratories with precision instruments: Automatic fire alarm system and fixed automatic CO2 fire extinguishing system shall be provided in addition to portable fire extinguishers.
v) Buildings dealing with flammable liquids: Automatic foam or CO2 or dry chemical fire extinguishing system required along with portable fire extinguishers.
vi) Solvent storage in office: Automatic foam or CO2 or dry chemical fire extinguishing system required along with portable fire extinguishers.
vii) Computer installation: Automatic fire alarm system and fixed CO2 or fixed vaporising liquid fire extinguishing system required along with portable fire extinguishers.
viii) Electrical switch board room/sub-station: Automatic fire alarm and/or fixed CO2 or fixed vaporising liquid fire extinguishing system shall be installed along with portable fire extinguishers.
ix) Space under false ceiling: Automatic fire alarm system shall be installed.
### 5.7.2 Occupancy F2: Small Shops and Markets
i) Whole sale establishments, warehouses, transport booking establishments: Automatic sprinkler or automatic fire alarm system shall be provided along with portable fire extinguishers.
ii) Other premises (other than shops, stores, markets etc.): Automatic fire alarm system shall be provided along with portable fire extinguishers.
### 5.7.3 Occupancy F3: Large Shops and Markets
i) Shopping arcade with central corridors open to sky: Automatic fire alarm system and portable fire extinguishers shall be provided.
ii) Shopping complex under covered roof with areas more than 500m² on each floor: Automatic fire alarm and venting system, fixed and portable CO2 fire extinguisher shall be installed. Provision for portable fire pump with relevant accessories and conservance of water shall be provided along with trained personnel.
iii) Underground shopping complex: Automatic fire alarm, sprinklers and fixed and portable CO2 fire extinguisher shall be installed.
### 5.7.4 Occupancy F4: Garages and Petrol Stations
i) Petrol pump station, automobile garages: Fixed wall hung CO2 or dry chemical fire extinguisher shall be provided or arrangements shall be made as directed by the authority.
ii) Aircraft hangars: Foam or dry chemical or CO2 Fire extinguishers shall be installed.
### 5.7.5 Occupancy F5: Essential Services
Automatic fire alarm system and automatic fire sprinkler shall be provided along with portable fire extinguishers.
## 5.8 OCCUPANCY G: INDUSTRIAL
In addition to the general provision covered under Chapter 4, the following requirements for Occupancy G shall be complied with.
### 5.8.1 Occupancy G1: Low Hazard Industries
Manually operated electric fire alarm system shall be installed along with portable fire extinguishers.
### 5.8.2 Occupancy G2: Moderate Hazard Industries
a) Area upto 750 m² shall be installed with automatic fire alarm system along with portable fire extinguishers.
b) Area above 750 m² shall be fitted with Automatic sprinkler and/or automatic fire alarms system along with portable fire extinguishers.
## 5.9 OCCUPANCY H: STORAGE
In addition to the general provisions covered under Chapter 4, the following requirements for Occupancy H shall be complied with.
### 5.9.1 Occupancy H1: Low Fire Risk Storage
Manually operated electric fire alarm system shall be installed. Depending on the type of materials to be stored, other detection and fire fighting system shall be provided as per direction of the Authority.
### 5.9.2 Occupancy H2: Moderate Fire Risk Storage
Automatic fire alarm system shall be installed. Depending on the type of stored materials other fire detection and fire fighting arrangement shall be provided as per direction of the Authority.
## 5.10 OCCUPANCY J: HAZARDOUS
In addition to the general provisions covered under Chapter 4, the following requirements for the occupancy group shall be complied with.
All hazardous occupancies shall be installed with Automatic Fire Alarm and Sprinkler System. CO2 or foam or dry chemical extinguishing system shall be installed as per direction of the Authority.
## 5.11 OCCUPANCY K: MISCELLANEOUS
Fire detection and fire fighting arrangements shall be installed as and where directed and approved by the Authority.
> **Related Appendix:**
> Appendix D Special Requirements of Buildings more than 20 Metre High
# Part IV: Fire Protection
Source: https://docs.sayed.app/bnbc2006/part-4-fire-protection/index
Precautionary requirements, means of escape, and fire detection and extinguishing systems.
Part 4 covers fire protection requirements: general provisions, precautionary requirements, means of escape, fire detection and extinguishing equipment, and requirements specific to various occupancies.
## Chapters
Scope and general fire-protection provisions.
Precautionary measures against fire hazards.
Exit design, stairways, and egress requirements.
Fire detection, alarm, and extinguishing systems.
Fire-protection requirements by occupancy type.
## Appendices
Supporting appendices for Part 4.
# Chapter 1: Scope and Definitions
Source: https://docs.sayed.app/bnbc2006/part-5-building-materials/chapter-1-scope-and-definitions
## 1.1 SCOPE
This part specifies the minimum requirements of materials to be complied with in buildings and works under the provisions of the Code.
For each of the building materials the applicable standard specifications and test methods are listed. All materials shall conform to these standards.
The list of standards given in this part of the Code would be augmented from time to time by amendments, revisions and additions of which the Authority shall take cognizance. The latest version of a specification shall, as far as practicable, be applied in order to fulfil the requirements of this part.
In view of the limited number of Bangladesh Standards for building materials available at the present time, a number of standards of other countries have been referenced in this Code as applicable standards. As more Bangladesh Standards regarding building materials become available, these after adoption by amendment of the Code, shall supplement and /or replace the relevant standards listed in this part.
## 1.2 TERMINOLOGY
This section provides an alphabetical list of the terms used in and applicable to this part of the Code. In case of any conflict or contradiction between a definition given in this section and that in Part 1, the meaning provided in this part shall govern for interpretation of the provisions of this part.
ACTUAL DIMENSIONS: Measured dimensions of a designated item.
ADMIXTURE: Material other than water, aggregate, or hydraulic cement used as an ingredient of concrete and added to concrete before or during its mixing to modify its properties.
AGGREGATE, LIGHTWEIGHT: Aggregate with a dry, loose weight of 11.25 kN/m3.
AGGREGATE: Granular material, such as sand, gravel, crushed stone, crushed brick and iron blast-furnace slag, when used with a cementing medium forms a hydraulic cement concrete or mortar.
CONCRETE: A mixture of Portland cement or any other hydraulic cement, fine aggregate, coarse aggregate and water, with or without admixtures.
DEFORMED REINFORCEMENT: Deformed reinforcing bars, bar and rod mats, deformed wire, welded smooth wire fabric and welded deformed wire fabric.
FIBREBOARD: A fibre-felted, homogenous panel made from lignocellulosic fibres (usually wood or cane) and having a unit weight of less than 5 kN/m3 but more than 1.6 kN/m3.
GROUTED HOLLOW-UNIT MASONRY: Form of grouted masonry construction in which certain designated cells of hollow units are continuously filled with grout.
HARDBOARD: A fibre-felted homogenous panel made from lignocellulosic fibres consolidated under heat and pressure in a hot press to a density not less than 4.9 kN/m3.
HOLLOW MASONRY UNIT: A masonry unit whose net cross-sectional area in every plane parallel to the bearing surface is less than 75 per cent of the gross cross-sectional area in the same plane.
MASONRY UNIT: Brick, tile, stone, glass-block or concrete-block used in masonry constructions.
NOMINAL DIMENSIONS: Nominal dimensions of masonry units are equal to their specified dimensions plus the thickness of the joint with which the unit is laid.
PARTICLE BOARD: A manufactured panel product consisting of particles of wood or combinations of wood particles and wood fibres cemented together with synthetic resins or other suitable bonding system by an appropriate bonding process.
PLAIN CONCRETE: Concrete that does not conform to the definition of reinforced concrete.
PLAIN REINFORCEMENT: Reinforcement that does not conform to definition of deformed reinforcement.
PLYWOOD: A built-up panel of laminated veneers.
PRECAST CONCRETE: Plain or reinforced concrete element cast separately before they are fixed in position.
PRESTRESSED CONCRETE: Reinforced concrete in which internal stresses have been introduced to reduce potential tensile stresses in concrete resulting from loads.
REINFORCED CONCRETE: Concrete containing adequate reinforcement, prestressed or non-prestressed, and designed on the assumption that the two materials act together in resisting forces.
REINFORCED MASONRY: Form of masonry construction in which reinforcement acting in conjunction with the masonry is used to resist designed forces.
REINFORCEMENT: Reinforcing bars, plain or deformed, excluding prestressing tendons, bar and rod mats, welded smooth wire fabric and welded deformed wire fabric used in concrete.
SOLID MASONRY UNIT: A masonry unit whose net cross-sectional area in every plane parallel to the bearing surface is 75 per cent or more of the gross cross-sectional area in the same plane.
SPIRAL REINFORCEMENT: Continuously wound reinforcement in the form of a cylindrical helix.
STIRRUP: Reinforcement used to resist shear and torsion stresses in structural member; typically bars, wires, or welded wire fabric (smooth or deformed) bent into L, U or rectangular shapes and located perpendicular to or at an angle to longitudinal reinforcement. (The term "Stirrup" is usually applied to lateral reinforcement in flexural members and the term "ties" to those in compression members).
STRUCTURAL GLUED LAMINATED TIMBER: Any member comprising an assembly of laminations of lumber in which the grain of all laminations is approximately parallel longitudinally in which the laminations are bonded with adhesives.
TENDON: Steel element such as wire, cable, bar, rod or strand, or a bundle of such elements, used to impart prestress to concrete.
TIE: A loop of reinforcing bar or wire enclosing longitudinal reinforcement.
YIELD STRENGTH: The stress at which plastic deformation takes place under constant or reduced load.
# Chapter 2: Materials
Source: https://docs.sayed.app/bnbc2006/part-5-building-materials/chapter-2-materials
## 2.1 GENERAL
Materials used for the construction of buildings shall conform to standard specifications listed in this part of
the Code. Any deviation from the type design or architectural detail from those aac in these standards
nr iad accepted by the Building Official as long as the materials standards specified therein are conformed
with.
### 2.1.1 New or Alternative Materials
The provisions of this part are not intended to prevent the use of any new and alternative materials. Any
such material may be approved provided it is shown to be satisfactory for the purpose intended and at least
the equivalent of that required in this part in quality, strength, effectiveness, fire resistiveness, durability,
safety, maintenance and compatibility.
Approval in writing shall be obtained by the owner or his agent before any new, alternative or equivalent
materials are used. The es Official shall base such es, on the principle set forth in the previous
paragraph and shall require that specified tests be made (Sec 2.1.4) or sufficient evidence or proof be
submitted, at the expense of the owner or his agent, to substantiate any claim for the proposed material. (See
Part 2, Administration and Enforcement).
### 2.1.2 Used Materials
The provisions of this part do not preclude the use of used or reclaimed materials provided such materials
meet the applicable requirements as for new materials for their intended use.
### 2.1.3 Storage of Materials
All building materials shall be stored at the building site(s) in such a way as to prevent deterioration or the
ae or impairment of their structural and other essential properties (See Part 7, Construction Practices and
afety).
Methods of Test
Every test of material required in this part, or by the Building Official, for the control of quality and for the
fulfilment of design and specification requirements, shall be carried out in accordance with a standard method
of test issued by the Bangladesh Standards and Testing Institution. In the absence of Bangladesh Standards,
Part 5
Building Materials
the Building Official shall determine the test procedures. Laboratory tests shall be conducted by recognized
laboratories acceptable to the Building Official.
If, in the opinion of the Building Official, there is insufficient evidence of compliance with any of the
provisions of the Code or there is evidence that any material or construction does not conform to the
requirements of this Code, the Building Official may require tests to be performed as proof of compliance. The
cost of any such test shall be borne by the owner.
The manufacturer or supplier shall satisfy himself that the materials conform to the relevant standards and if
requested shall furnish a certificate or guarantee to this effect.
## 2.2 MASONRY
### 2.2.1 Aggregates
Aggregates for masonry shall conform to the standards listed as follows: ASTM C144, Aggregates for
Masonry Mortar; ASTM C404, Aggregates for Masonry Grout; ASTM C331, Lightweight Aggregates for
Concrete Masonry Units (the applicable standards for masonry are listed at the end of this section).
### 2.2.2 Cement
Cement for masonry shall conform to the standards listed as follows: BDS 232: 1974, Portland Cement
(Ordinary and Rapid Hardening) or ASTM C150, Portland Cement; ASTM C91, Masonry Cement; ASTM
C595, Blended Hydraulic Cements.
### 2.2.3 Lime
Limes for meseney shall conform to the standards listed as follows: ASTM C5, Quicklime for Structural
Purposes; ASTM C207, Hydrated Lime for Masonry Purposes.
### 2.2.4 Masonry Units
a) Clay: Masonry units of clay (or shale) shall conform to the standards listed as follows: BDS 208: 1980,
Common Building Clay Bricks (First Revision); BDS 1249:1989, Acid Resistant Bricks; BDS 1250: 1989,
Burnt Clay Facing Bricks; BDS 1263: 1990, Burnt Clay Hollow Bricks for Walls and Partitions; ASTM
C34, Structural Clay Pog cio 2 Tile; ASTM C212, Structural Clay Facing Tile; ASTM C56
Structural Clay Non-Load-Bearing Tile; and IS 7556-1975 Burnt Clay Jallies.
b) Concrete : Concrete masonry units shall conform to the standards listed as follows: ASTM C90, Hollow
Load-Bearing Concrete Masonry Units; ASTM C129, Non-Load Bearing Units; ASTM C145, Solid
Load-Bearing Units; ASTM C55, Concrete Building Bricks.
c) Others
i) Calcium Silicate: Calcium Silicate Face Brick (Sand-Lime Brick) shall conform to ASTM standard
specification C73-75.
ii) Glazed Masonry Units: Glazed Masonry building units shall conform to the standards listed as
follows: ASTM C126, Ceramic-Glazed Structural Cla ses | Tile, Facing Brick, and Solid
Masonry Units; or ASTM C744, Prefaced Concrete and Calcium Silicate Masonry Units.
iii) Glass Block: Glass block may be solid or hollow and contain inserts; all mortar contact surfaces
shall be treated to ensure adhesion between mortar and glass.
iv) | Unburnt Clay Masonry Units: Masonry of unburnt clay units including cement stabilized and
lime stabilized blocks shall not be used, in any building more than one storey in height.
v) Architectural Terra Cotta: All architectural terra cotta units shall be formed with a strong
homogeneous body of hard-burnt weather-resistant clay which Lae off a sharp metallic ring
when struck. All units shall be formed to engage securely with and anchor to the structural frame
or masonry wall.
vi) Natural Stone: Natural stone for masonry shall be sound and free from loose friable inclusions.
Natural stone shall have the strength and fire resistance required for the intended use.
vii) Cast Stone: All cast stone shall be fabricated of concrete or other approved materials of required
strength, durability and fire resistance for the intended use and shall be reinforced where
necessary.
viii) Second Hand Units: Second hand masonry units shall not be used unless the units conform to the
requirements for new units. The units shall be of whole, sound material and be free form cracks
and other defects that would interfere with proper laying or use. All old mortar shall be cleaned
from the units before reuse.
### 2.2.5 Mortar
Mortar shall consist of a mixture of cementitious material and aggregates to which sufficient water and
approved additives, if any, have been added to achieve a workable, plastic consistency. Cementitious
materials for mortar shall be one or more of the following: lime, masonry cement, Portland cement and mortar
cement. Mortar for masonry construction other than the installation of ceramic tile shall conform to the
requirements of ASTM C270, Mortar for Unit Masonry .
### 2.2.6 Grout
Grout shall consist of a mixture of cementitious materials and aggregates to which water has been added such
that the mixture will flow without segregation of the constituents. Cenectiteds materials for grout shall be
one or both of the following: Lime and Portland cement. Grout shall have a minimum compressive strength of
13 MPa. Grout used in reinforced and nonreinforced masonry construction shall conform to the requirements
of ASTM C476, Grout for Masonry.
### 2.2.7 Mortar for Ceramic Wall and Floor Tile
Portland cement mortars for installing ceramic wall and floor tile shall comply with ANSI A 108.1 listed in
Sec 2.2.11 and be of the composition specified in Table 5.2.1.
Table 5.2.1 Ceramic Tile Mortar Compositions
| Location | Coat | Composition |
| :------- | :----------------------------- | :------------------------------------------------------------------------------------ |
| Walls | Scratchcoat | 1 cement; 1/5 hydrated lime; \* 4 dry or 5 damp sand |
| | Setting bed and levelling coat | 1 cement; 1/2 hydrated lime; 5 damp sand to 1 cement; 1 hydrated lime; 7 damp sand |
| Floors | Setting bed | 1 cement; 1/10 hydrated lime; 5 dry or 6 damp sand; or 1 cement; 5 dry or 6 damp sand |
| Ceilings | Scratch coat and sand bed | 1 cement; 1/2 hydrated lime; 2 1/2 dry sand or 3 damp sand |
Note: \* Lime may be excluded from the mortar if trial mixes indicate that the desired workability and performance are achieved without lime.
### 2.2.8 Metal Ties and Anchors
Metal ties and anchors shall conform to the standards listed as follows: ASTM A82, Wire Anchor and Ties;
and ASTM A366 M, Sheet Metal Anchors and Ties.
### 2.2.9 Reinforcement
Reinforcement in masonry shall conform to the standards listed as follows: ASTM A82, Cold Drawn Steel
Wire for Concrete Reinforcement; ASTM A615M, Deformed and Plain Billet Steel Bars; ASTM A616M, Rail-
Steel Deformed and Plain Bars; ASTM A617M, Axle-Steel Deformed and Plain Bars; ASTM A706M, Low-
Alloy Steel Deformed Bars; ASTM A767M, Zinc-Coated (Galvanized) Steel Bars; and ASTM A775M, Epoxy
* Coated Reinforcing Steel Bars.
### 2.2.10 Water
Water used in mortar or grout shall be clean and free of deleterious amounts of acid, alkalis or organic
material or other harmful substances.
### 2.2.11 Applicable Standards for Masonry
The applicable standards for Masonry are listed below:
BDS 208 : 1980 Specification for Common Building Clay Bricks (First Revision);
BDS 232 : 1974 Specification for Portland Cement (Ordinary and Rapid Hardening) (First
Revision);
BDS 1249 ; 1989 Specification for Acid Resistant Bricks;
BDS 1250 : 1989 Specification for Burnt Clay Facing Bricks;
BDS 1263 : 1990 Specification for Burnt Clay Hollow Bricks for Walls and Partitions;
ANSI A108-1 S a for the Installation of Ceramic Tile with Portland Cement
ortar;
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
\_ ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
## 2.3 STEEL
A82-90a
A366M-91
A615-90
A615M-90
A616M-90
A617M-90
A706M-90
A76M-90
A775M-91b
C5-79(1988)
C34-84 (1990)
C55-85
C56-71 (1986)
C73-85 (1989)
C90-91
C126-86
C129-85(1990)
C144-89
C145-85
€207-79(1988)
€212-60 (1986)
€331-89
C476-83
C595-89
C744-73(1985)
### 2.3.1 Reinforcing Steel
Reinforcing steel shall comply with the requirements specified in Sec 2.4.6 in this Part.
Specification for Steel Wire, Plain, for Concrete Reinforcement;
Specification for Steel Sheet, Carbon, Cold-Rolled, Commercial Quality;
Specification for Deformed and Plain Billet-steel Bars for Concrete
Reinforcement;
Specification for Deformed and Plain Billet-Steel Bars for Concrete
Reinforcement ;
Specification for Rail-Steel Deformed and Plain Bars for Concrete
Reinforcement;
Specification for Axle-Steel Deformed and Plain Bars for Concrete
Reinforcement;
Specification for Low-Alloy Steel Deformed Bars for Concrete
Reinforcement;
Specification for Zinc-Coated (Galvanized) Steel Bars for Concrete
Reinforcement;
Specification for Epoxy-Coated Reinforcing Steel Bars;
Specification for Quicklime for Structural Purposes;
Specification for Structural Clay Load Bearing Wall Tile;
Specification for Concrete Building Brick;
Specification for Structural Clay Non-Load -Bearing Tile;
Specification for Calcium Silicate Face Brick (Sand-Lime Brick);
Specification for Hollow Load-Bearing Concrete Masonry Units;
Specification for Masonry Cement;
Specification for Ceramic Glazed Structural Clay Facing Tile, Facing Brick,
and Solid Masonry Units;
Specification for Non-Load-Bearing Concrete Masonry Units;
Specification for Aggregate for Masonry Mortar;
Specification for Solid Load-Bearing Concrete Masonry Unit;
Specification for Portland Cement;
Specification for Hydrated Lime for Masonry Purposes;
Specification for Structural Clay Facing Tile;
Specification for Mortar for Unit Masonry;
Specification for Lightweight Aggregates for Concrete Masonry Units;
Specification for Aggregates for Masonry Grout;
Specification for Grout for Masonry;
Specification for Blended Hydraulic Cements;
Specification for Prefaced Concrete and Calcium Silicate Masonry Units;
### 2.3.2 Structural Steel
Structural steel shall conform to Bangladesh Standards BDS 878 : 1978, Specification for Weldable
Structural Steels; BDS 1355 : 1992, Dimensions and Properties of Hot Rolled Steel Beam, Column, Channel
and Angle Sections. Where Bangladesh standards are not available, the relevant standards listed below shall
be applicable.
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
A27M-91
A36 M-91
A48-88(1990)
A53-90
A148 M-90
A242 M-91
A252-90
A283 M-91
A307-91
A325-91
A325 M-91
A336 M-89
A446 M-91
A449-91
A490 M-91
A500-90
A501-89
A514 M-91
A529 M-89
A563 M-91
A569 M-91
A570 M-91
A572 M-91
A588 M-91
A606-91
Specifications for Steel, Castings, Carbon, for General Application;
Specification for Structural Steel;
Specification for Grey Iron Castings;
Specifications for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated Welded
and Seamless;
Specifications for Steel Castings, High Strength, for Structural Purposes;
Specification for High-Strength Low-Alloy Structural Steel;
Specification for Welded and Seamless Steel Pipe Piles;
Spansion for Low and Interntediate Tensile Strength Carbon Steel
Plates; 3
Specification for Carbon Steel Bolts and studs, 413.7 MPa, (60000 psi)
ensile Strength;
Specification for Structural Bolts, Heat Treated, 827.4/861.9 MPa
(20 /125 ksi) Minimum Tensile Strength;
Specification for High Strength Bolts for Structural Steel Joints;
eee aes for Steel Forgings, Alloy; for Pressure and High-Temperature
‘arts;
Specification for Steel, Sheet, Zinc Coated (Galvanized) by the Hot-Dip
Process, Structural (Physical) Quality;
Specification for Quenched and Tempered Steel Bolts and Studs;
Specification for High-Strength Steel Bolts for Structural Steel Joints;
Specification for Cold-Formed Welded and Seamless Carbon Steel
Structural Tubing in Rounds and Shapes;
Sperication for Hot-Formed Welded and Seamless Carbon Steel Structural
‘ubing;
Specification for High-Yield Strength, Quenched and Tempered Alloy Steel
Plate, Suitable for Welding;
Specification for Structural Steel with 290 MPa (42 ksi) Minimum Yield
Point (13 mm or 4 in Maximum Thickness);
Specification for Carbon and Alloy Steel Nuts;
Specification for Steel, Carbon (0.15 Maximum, per cent), Hot-Rolled Sheet
and Strip Commercial Quality;
tae for Steel Sheet and Strip, Carbon, Hot-Rolled, Structural
ality;
Specification for High Strength, Low-Alloy Columbium-Vanadium Steels of
Structural Quality;
Specification for High Strength Low-Alloy Structural Steel with 345 MPa
en ksi) Minimum Yield Point to 100 mm (4 in.) Thick;
Specification for Steel; Sheet and Strip, High-Strength, Low-Alloy, Hot-
Rolled and Cold-Rolled, with Improved Atmospheric Corrosion Resistance;
ASTM A607-91 Specification for Steel Sheet and Strip, High-Strength, Low-Alloy
olumbium or Vanadium, or Both, Hot-Rolled and Cold-Rolled;
ASTM A611-91 Specification for Steel, Carbon, Cold-Rolled, Structural Quality;
ASTM A618-90 Specification for Hot-Formed Welded and Seamless High-Strength Low-
Alloy Structural Tubing;
ASTM A666-91 Specification for Austenitic Stainless Steel, Sheet, Strip, Plate and Flat Bar;
ASTM A668-90 ages for Steel Forgings, Carbon and Alloy, for General Industrial
Se;
ASTM A690 M-90 Specification for High-Strength Low-Alloy Steel H Piles and Sheet Piling
for Use in Marine Environments;
ASTM A715-91 Specification for Steel Sheet and Strip, High Strength, Low-Alloy, Hot-
Rolled and Steel, Sheet Cold-Rolled, High-Strength, Low-Alloy with
Improved Formability;
ASTM A852 M-91 Specification for Quenched and Tempered Low-Alloy Structural Steel Plate
with 485 MPa (70 ksi) Minimum Yield Strength to 100 mm (4 in.) Thick.
### 2.3.3 Steel Plate, Sheet and Strips
These shall conform to the following standards.
BDS 681 : 1968 Specification for Hot-Rolled Steel Strips (under revision);
BDS 868 : 1978 Code of Practice for Galvanized Corrugated Sheet Roof and Wall
Coverings;
BDS 1122 : 1985 Specification for Hot-dip Galvanized Steel Sheet and Coil;
IS 412: 1975 Specification for Expanded Metal Steel Sheets for General Purposes
(Second Revision);
IS 1079 : 1973 Specification for Hot-Rolled Carbon Steel Sheet and Strip (Third Revision);
IS 4030 : 1973 Specification for Cold-Rolled Carbon Steel Strip for General Engineering
Purposes (First Revision);
IS 7226 : 1974 Specification for Cold-Rolled Medium, High Carbon and Low-Alloy Steel
Strip for General Engineering Purposes;
IS 3502 : 1966 Specification for Steel Chequered Plates.
For steel plate, sheet and strip, where Bangladesh Standards are not available, the relevant ASTM standards
(listed below) shall be applicable.
ASTM A109M-91 Specifications for Steel, Strip, Carbon, Cold-Rolled;
ASTM A123-89 Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel
Products;
ASTM A167-91 ane for Stainless and Heat-Resisting Chromium-Nickel Steel Plate,
Sheet, and Strip;
ASTM A176-90 Specification for Stainless and Heat-Resisting Chromium-Steel Plate, Sheet,
and Strip;
ASTM A240-91 Specification for Heat-Resisting Chromium and Chromium-Nickel Stainless
Steel Plate, Sheet, and Strip for Pressure Vessels;
ASTM A263-91 Specification for Corrosion-Resisting chromium Steel-Clad Plate, Sheet, and
Strip;
ASTM A264-91 Specification for Stainless Chromium-Nickel Steel-Clad Steel Plate, and
Strip;
ASTM A285/A285 M-90 Specification for Pressure Vessel Plates, Carbon Steel, Low and
Intermediate-Tensile Strength;
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
A328/A328 M-90
A366/A366M-91
414/A414 M-91
A424-91
A444/A444M-89
A463-88
A480/A480 M-91
A505-87
A506-91
A506-91
A527 /A527M-90
A568/A568 M-91
A569A569 M-91
A570/A570 M-91
A577/A577 M-90
A578/A578 M-90
A591/A591 M-89
A599-84
A606-91
A607-91
A611-91
A635/A635 M-91
A642/A642 M-90
A666-91
690/A690 M-90
A715-91
Specification for Steel Sheet Piling;
Specification for Steel Sheet, Carbon, Cold-Rolled, Commercial Quality;
Specification for Steel Sheet, Carbon, for Pressure Vessels;
Specification for Steel, Sheet, for Porecelain Enameling;
Specification for Steel Sheet, Zinc-Coated (Galvanized) by the Hot-Dip
Process for Storm Sewer and Drainage Pipe;
Specification for Steel Sheet Cold-Rolled, Aluminum-Coated, Type 1 and
ype 2;
Specification for General Requirements for Flat-Rolled Stainless and Heat-
Resisting Steel Plate, Sheet, and Strip;
Specification for Steel, Sheet and Strip, Alloy, Hot-Rolled and Cold-Rolled,
neral Requirements for;
Specification for Steel, Sheet and Strip, Alloy, Hot-Rolled and Cold-Rolled,
egular Quality and Structural Quality;
Specification for Steel, Sheet and Strip, Alloy, Hot-Rolled and Cold-Rolled, ‘
Drawing Quality;
Specification for Steel Sheet, Zinc-Coated (Galvanized) by the Hot-Dip
Process, Lock-forming Quality;
Specification for Steel, Sheet, Carbon, and High-Strength, Low-Alloy, Hot-
Rolled and Cold-Rolled, General Requirements for;
Specification for Steel, Carbon (0.15 Maximum, Per cent), Hot-Rolled Sheet
and Strip Commercial Quality;
S eo for Steel, Sheet and Strip, Carbon, Hot-Rolled, Structural
ality;
Specification for Ultrasonic Angle-Beam Examination of Steel Plates;
Specification for Straight-Beam Ultrasonic Examination of Plain and Clad
Steel Plates for Special Applications;
Specification for Steel Sheet, Electrolytic Zinc-Coated, for Light Coating
ass Applications;
Specification for Steel Sheet, Cold-Rolled, Tin-Coated by Electro-
deposition;
Specification for Steel, Sheet and bal High-Strength, Low-Alloy, Hot-
Rolled and Cold-Rolled, with Improved Atmospheric Corrosion Resistance;
Specification for Steel, Sheet and Strip, High-Strength, Low-Alloy,
olumbium or Vanadium, or Both, Hot-Rolled and Cold-Rolled;
Specification for Steel, Sheet, Carbon, Cold-Rolled, Structural Quality;
Specification for Steel, Sheet and Strip, Heavy-Thickness Coils, Carbon,
ot-Rolled;
Specification for Steel Sheet, Zinc-Coated (Galvanized) by the Hot-dip
Process, Drawing Quality, Special Killed;
Specification for Austenitic Stainless Steel, Sheet, Strip, Plate, and Flat Bar;
Specification for High-Strength Low-Alloy Steel H-Piles and Sheet Piling
for Use in Marine Environments;
Specification for Steel Sheet and Strip, ee iene Low-Alloy, Hot-
Rolled, and Steel Sheet, Cold-Rolled, High-Strength, Low-Alloy, with
Improved Formability;
ASTM
ASTM
ASTM
ASTM
### 2.3.4 Steel Pipe, Tube and Fittings
These items shall conform to the following standards :
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
A775/A775 M-91
A792 M-85
A857-90
A875/A875 M-88
A53-90
A105/A105M-90
A106-91
A134-90
A139-90
A181/A181M-90
A182/A182M-91
A211-75 (1985)
A234/A234M-90
A252-90
A254-91
A268/A268M-91
A269-90
A270-90
A312/A312m-91
A333/A333m-91
A334/A334M-91
A403/A403M-91
A420/A420M-91
A423/A423M-90
A450/A450M-91
A500-90
A501-89
Specification for Epoxy-Coated Reinforcing Steel Bars;
Specification for Steel Sheet, Aluminum-Zinc Alloy-Coated by the Hot-Dip
Process. General Requirements (Metric);
Specification for Steel Sheet Piling, Cold Formed, Light Gage;
Fe igre for Steel Sheet, Zinc-5 % Aluminum Alloy Metallic-Coated by
the Hot-Dip Process;
Specification for Pipe, Steel, Black and Hot-Dipped, Zine Coated Welded
and Seamless;
Specification for Forgings, Carbon Steel, for Piping Components;
Specification for Seamless Carbon Steel Pipe for High-Temperature Service;
Specification for Pipe Steel Electric - Fusion (Arc) - Welded (sizes NPS 16
and Over);
Specification for Electric-Fusion (Arc) - Welded Steel Pipe (NPS-4 and
er);
Specification for Forgings, Carbon Steel, for General-Purpose Piping;
Specification for Forged or Rolled Alloy-Steel Pipe Flanges, Forged
Fittings, and Valves and Parts for High-Temperature Service;
Specification for Spiral-Welded Steel or Iron Pipe;
Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel
for Moderate and Elevated Temperatures;
Specification for Welded and Seamless Steel Pipe Piles;
Specification for Copper-Brazed Steel Tubing;
Specification for Seamless and Welded Ferritic and Martenistic Stainless
Steel Tubing for General Service;
Specification for Seamless and Welded Austenitic Stainless Steel Tubing
for General Service;
S eeueeton for Seamless and Welded Austenitic Stainless Steel Sanitary
‘ubing;
Specification for Seamless and Welded Austenitic Stainless Steel Pipes;
Specification for Seamless and Welded Steel Pipe for Low-Temperature
Service;
Specification for Seamless and Welded Carbon and Alloy-Steel Tubes for
Low-Temperature Service;
Specification Wrought Austenitic Stainless Steel Piping Fittings;
Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel
for Low-Temperature Service;
Specification for Seamless and Electric-Welded Low-Alloy-Steel Tubes;
Specification for General Requirements for Carbon, Ferritic Alloy, and
Austenitic Alloy steel Tubes;
Specification for Cold-Formed Welded and Seamless Carbon Steel
Structural Tubing in Rounds and Shapes;
Specification for Hot-Formed Welded and Seamless Carbon Steel Structural
tubing;
ASTM A522/A522M-90 Specification for Forged or Rolled 8 and 9% Nickel Alloy Steel Flanges,
Fittings, Valves, and Parts for Low Temperature Service;
ASTM A524-89 esa ee for Seamless Carbon Steel Pipe for Atmospheric and Lower
emperatures;
ASTM A530/A530M-91 Specification for General Requirements for Specialized Carbon and Alloy
Steel Pipe;
ASTM A589-89 Specification for Seamless and Welded Carbon Steel Water-Well Pipe;
ASTM A618-90 Specification for Hot-Formed Welded and Seamless High-Strength Low-
Alloy Structural Tubing;
ASTM A632-90 ct Aaah crt for Seamless and Welded Austenitic Stainless Steel Tubing
(Small-Diameter) for General Service;
ASTM A707/A707M-90 7 Secor for Flanges, Forged, Carbon and Alloy-Steel for Low-
emperature Service;
ASTM A733-89 Specification for Welded and Seamless Carbon Steel and Austenitic
Stainless Steel Pipe Nipples;
ASTM A778-90 Specification for Welded, Unannealed Austenitic Stainless Steel Tubular
Products;
ASTM A807-88 Practice for Installing Factory-Made Corrugated Steel Pipe for Sewers and
Other Applications;
ASTM A865-89 Steet for Threaded a a ae Steel, Black or Zinc-Coated
(Galvanized) Welded or Seamless, for Use in Steel Pipe Joints.
### 2.3.5 Steel Bars, Wire and Wire Rods
These shall conform to the following standards.
ASTM A29 M-91 Specification for Steel Bars, Carbon and Alloy, Hot-Wrought and Cold-
inished, General Requirements for;
ASTM A49-87 Specification for Heat-Treated Carbon Steel Joint Bars;
ASTM A108-90 Specification for Steel Bars, Carbon Cold Finished, Standard Quality;
ASTM A116-88 Specification for Zinc Coated (galvanized) Steel Woven Wire Fence Fabric;
ASTM A185-90a Specification for Steel Welded Wire Fabric, Plain for Concrete
Reinforcement;
ASTM A227 M-91 Specification for Steel Wire, Cold-Drawn for Mechanical Springs;
ASTM A228 M-91 Specification for Steel Wire, Music Spring Quality;
ASTM A229 M-91 Specification for Steel Wire, Oil-Tempered for Mechanical Springs;
ASTM A276-91 Specification for Stainless and Heat-Resisting Steel Bars and Shapes;
ASTM A311 M-90 Specification for Stress-Relieved Cold-Drawn Carbon Steel Bars Subject to
lechanical Property Requirements;
ASTM A321-90 Specification for Steel Bars, Carbon, Quenched and Tempered;
ASTM A322-91 Specification for Steel Bars, Alloy, Standard Grades;
ASTM A331-90 Specification for Steel Bars, Alloy, Cold-Finished;
ASTM A368-82 Specification for Stainless and Heat-Resisting Steel Wire Stand;
ASTM A434-90 Specification for Steel Bars, Alloy, Hot-Wrought or Cold-finished,
tuenched and Tempered;
ASTM A475-89 Specification for Zinc-Coated Steel Wire Strand;
ASTM A478-91 Specification for Chromium-Nickel Stainless and Heat-Resisting Steel
eaving and Knitting Wire;
ASTM A479 M-91 Specification for Stainless and Heat-Resisting Steel Bars and Shapes for
se in Boilers and other Pressure Vessels;
ASTM A492-82(1987) Specification for Stainless and Heat-Resisting Steel Rope Wire;
ASTM A499-89 Specification for Steel Bars and Shapes, Carbon Rolled for "T" Rails;
ASTM A510-91 Specification for Wire Rods and Coarse Round Wire, Carbon Steel;
ASTM A575-89 Specification for Steel Bars, Carbon, Merchant Quality, M Grades;
ASTM A576-90 Specification for Steel Bars, Carbon, Hot-Wrought Special Quality;
ASTM A580-91 Specification for Stainless and Heat-Resisting Steel Wire;
ASTM A586-86(1991) Pe for Zinc-Coated Parallel and Helical Steel Wire Structural
trand;
ASTM A603-88 Specification for Zinc-Coated Steel Structural Wire Rope;
ASTM A627-88 Specification for Homogeneous Tool-Resisting Steel Bars for Security
Applications;
ASTM A629-88 Specification for Tool-Resisting Steel Flat Bars and Shapes for Security
Applications;
ASTM A641 M-91 Specification for Zinc-Coated (Galvanized) Carbon Steel Wire,
ASTM A663 M-89 Specification for Steel Bars, Carbon, Merchant Quality, Mechanical
Properties;
ASTM A666-91 Specification for Austenitic Stainless Steel Sheet, Strip, Plate and Flat Bar;
ASTM A706 M-90 Specification for Low-Alloy Steel Deformed Bars for Concrete
Reinforcement;
ASTM A764-90 Specification for Steel Wire, Carbon, Drawn Galvanized and Galvanized
at Size for Mechanical Springs;
ASTM = (C933-80(1990) Specification for Welded Wire Lath.
### 2.3.6 Steel Fasteners
Steel fasteners shall conform to the following standards :
ASTM A31-89 Specification for Steel Rivets and Bars for Rivets, Pressure Vessels;
ASTM \_ A183-83(1990) Specification for Carbon Steel Track Bolts and Nuts;
ASTM A193 M-91 Hf eagemansi for Alloy-Steel and Stainless Steel Bolting Materials for
'igh-Temperature Service;
ASTM A194 M-91 Specification for Carbon and Alloy Steel Nuts for Bolts for High-Pressure
and High-Temperature Service;
ASTM A307-91 a a ih for Carbon Steel Bolts and Steeds, 413.7 MPa (60,000 psi)
ensile Strength;
ASTM A320 M-91 Specification for Alloy-Steel Bolting Materials for Low-Temperature
Service;
ASTM A325 M-91 Specification for High-Strength Bolts for Structural Steel Joints;
ASTM A354-91 Specification for Quenched and Tempered Alloy-Steel Bolts, Studs and
other Externally Threaded Fasteners;
ASTM A437M-90 Specification for Alloy-Steel Turbine-Type Bolting Material Specially
eat Treated for High-Temperature Service;
ASTM A449-91 Specification for Quenched and Tempered Steel Bolts and Steeds;
ee
ASTM A489-90 Specification for Carbon Steel Eyebolts;
ASTM A490 M-91 pee age for ai Steel Bolts for Structural Steel Joints
(Classes 10.9 and 10.9.3);
ASTM A502-91 Specification for Steel Structural Rivets;
ASTM A540 M-88 Specification for Alloy-Steel Bolting Materials for Special Applications;
ASTM A563 M-91 Specification for Carbon and Alloy Steel Nuts;
ASTM = C954-86 Specification for Steel Drill Screws for the Application of Gypsum Board
or Metal Plaster Bases to Steel Studs from 0.84 mm (0.033 in.) to 2.84 mm
(0.112 in. ) in Thickness;
ASTM C955-88 Specification for Load-Bearing (Transverse and Axial) Steel Studs, Runner
Ch rack), and Bracing or Bridging, for Screw Application of Gypsum Board
and Metal Plaster Bases;
ASTM F959-90 Specification for Compressible-Washer-Type Direct Tension Indicators for
se with Structural Fasteners;
ASTM = C1002-88 Specification for Steel Drill Screws for the Application of Gypsum Board
or Metal Plaster Bases.
ASTM F436 M-91 Specification for Hardened Steel Washers;
ASTM F593-91 Specification Stainless Steel Bolts, Hex Cap Screws and Studs;
ASTM F594-91 Specification for Stainless Steel Nuts;
ASTM F844-90 Specification for Washers, Steel, Plain (Flat), Unhardened for General Use;
ASTM A574 M-90 Specification for Alloy-Steel Socket-Head Cap Screws;
ASTM A687-89 Specification for High-Strength Non headed Steel Bolts and Steeds;
ASTM C514-86 Specification for Nails for the Application of Gypsum Board;
### 2.3.7 Welding Electrodes and Wires
Welding electrodes and wires shall conform to the following standards :
IS 814 - 1974 Specification for Covered Electrodes for Arc Welding of Structural Steels :
Part I for Welding Products Other Than Sheets (Fourth Revision);
Part II for Welding Sheets (Fourth Revision);
IS 815-1974 Classification and Coding of Covered Electrodes for Metal Arc Welding of
Structural Steels (Second Revision);
IS 1278-1972 Specification for Filler Rods and Wires for Gas Welding (Second Revision);
IS 1395-1982 Specification for Low and Medium Alloy Steel Covered Electrodes for
anual Metal Arc Welding (Third Revision);
IS 3613-1974 Acceptance Tests for Wire Flux Combinations for Submerged-Arc Welding
of Structural Steel (First Revision);
IS 4972-1968 Specification for Resistance Spot-Welding Electrodes;
IS 6419-1971 Specification for Welding Rods and Base Electroes for Gas Shielded Are
elding of Structural Steel;
IS 6560-1972 Specification for Molybdenum and Chromium-Moly-bdenum Low Alloy
Steel Welding Rods and Base Electrodes for Gas Shielded Arc Welding;
IS 7280-1974 Specification for Base Wire Electrodes for Submerged-Arc Welding of
Structural Steels;
IS 8363-1976 Specification for Bare Wire Electrodes for Electroslag Welding of Streels;
BDS 239: 1963 Specification for Soft Solder (under revision);
ISO 9453:1990 Soft Solder Alloys-Chemical Compositions and Forms;
ISO 9454:1990 Soft Soldering Fluxes-Classification and Requirements
Part 1 : Classification, Labelling and Packaging;
ISO 9455-1: 1990 Soft Soldering Fluxes- Test Methods
Part 1: Determination of Non-volatile Matter, Gravimetric Method;
ISO 9455-8:1991 Soft Soldering Fluxes-Test Methods
Part 8 : Determination of Zinc Content;
ISO 9455-11:1991 Soft Soldering Fluxes-Test Methods
Part 11 : Solubility of Flux Residues;
ISO 9455-14:1991 Soft Soldering Fluxes-Test Methods
Part 14: Assessment of Tacriness of Flux Residues.
## 2.4 CEMENT AND CONCRETE
### 2.4.1 General
Materials used to produce concrete and admixtures for concrete shall comply with the requirements of this
section and those of Chapter 5, Part 6 of this Code.
### 2.4.2 Aggregates
Concrete aggregates shall conform to the following standards:
BDS 243 : 1963, Coarse and Fine Aggregates from Natural Sources for Concrete; ASTM C33, Concrete
Ag: regates; ASTM C330, Lightweight Aggregates for Structural Concrete; ASTM C637, Aggregates for
Radiation-Shielding Concrete; ASTM C332 , Lightweight Aggregate for Insulating Concrete; IS: 9142
Artificial Lightweight Aggregates for Concrete Masonry Units.
#### 2.4.2.1 Special Tests
Aggregates failing to meet the specifications listed in Sec 2.4.2 shall not be used
unless it is shown by special test or actual service experience to produce concrete of adequate strength and
durability and approved by the Building Official.
#### 2.4.2.2 Nominal Size
Nominal maximum size of coarse aggregate shall not be larger than:
i) One-fifth of the narrowest dimension between sides of forms; or
ii) One-third the depth of slabs; or
iii) Three fourths the minimum clear spacing between individual reinforcing bars or wires, bundles of bars,
or prestressing tendons or ducts.
Exception:
The above limitations regarding size of coarse aggregate may be waived if, in the judgment of the Engineer,
workability and methods of consolidation are such that concrete can be placed without honeycomb or voids.
### 2.4.3 Cement
Cement shall conform to the ae retckck Skirt oe BDS 232, Portland Cement (Ordinary and Rapid
Hardening); BDS 612, Sulphate Resisting Portland Cement-Type A; ASTM C150, Portland Cement; ASTM C
595, Blended Hydraulic Cements; and to other such,cements listed in ACI 318.
### 2.4.4 Water
Water used in mixing concrete shall be clean and free from injurious amounts of oils, alkalies salts, organic
materials or other substances that may be deleterious to concrete or reinforcement.
#### 2.4.4.1 Chloride Ions
Mixing water for prestressed concrete, or for concrete that will contain aluminium
embededments, including the portion of mixing water contributed in the form of free moisture on aggregates
shall not contain deleterious amounts of chloride ion. The maximum water-soluble chloride ion concentration
in concrete shall not exceed the limitations specified in Sec 5.5.3 of Part 6.
#### 2.4.4.2 Potability
Nonpotable water shall not be used in concrete unless the following are satisfied:
a) Selection of concrete proportions shall be based on concrete mixes using water from the such source.
b) Mortar test cubes made with nonpotable mixing water shall have 7-day and 28-day strengths equal to at
least 90 per cent of strengths of similar specimens made with potable water.
### 2.4.5 Admixtures
Admixtures to be used in concrete shall be subject to prior approval by the Building Official and shall comply
with Sec. 2.4.5.1 through 2.4.5.5.
#### 2.4.5.1 Chloride
Calcium chloride or admixtures containing chloride from admixture ingredients shall not
be used in prestressed concrete, concrete containing embedded aluminium in concrete cast against permanent
galvanized metal forms, or in concrete exposed to severe or very severe sulphate-containing solutions (see Sec
5.2.1 of Part 6).
#### 2.4.5.2 Standards
Air-entraining admixtures shall conform to ASTM C260. Water-reducing admixtures,
retarding admixtures, accelerating admixtures, water-reducing and retarding admixtures, and water-reducin
and accelerating admixtures shall conform to ASTM C494, Chemical Admixtures for Concrete, or AST!
C1017, Chemical Admixtures for Use in Producing Flowing Concrete.
#### 2.4.5.3 Pozzolanas
Fly ash (Pulverized Fuel Ash) or other pozzolans used as admixtures shall conform to
ASTM C618.
#### 2.4.5.4 Blast Furnace Slag
Ground granulated blast-furnace slag used as an admixture shall conform to
ASTM C989.
#### 2.4.5.5 Pigment for Coloured Concrete
Pigment for integrally coloured concrete shall conform to ASTM
979\.
### 2.4.6 Metal Reinforcement
Reinforcement and welding of reinforcement to be placed in concrete shall conform to the requirements of this
section.
a) Deformed Reinforcement : Deformed reinforcing bars shall conform to the following standards; BDS
1313, Steel Bars and Wires for Reinforcement of Concrete; BDS 580, Rolled Deformed Steel Bars
(intermediate grade) for Concrete Reinforcement; Reinforcement conforming to the ASTM, Standards:
A615M, Deformed and Plain Billet-Steel Bars; A616M, Rail-Steel Deformed and Plain Bars; A617M,
Axle-Steel Deformed and Plain Bars; A706M, Low-Alloy Steel Deformed Bars; A767M, Zinc Coated
(Galvanized) Steel Bars; and A775M, Epoxy-Coated Reinforcing Steel.
Deformed reinforcing bars with a specified yield strength ( iby ) exceeding 410 MPa may be used, provided
fy shall be the stress corresponding to a strain of 0.35 per cent and the bars otherwise conform to
ASTM standards noted above. Fabricated deformed steel bar mats conforming to ASTM A184M and
deformed steel wire complying with ASTM A496 may be used. Deformed wire for concrete reinforcement
shall not be smaller than size D4 (Nominal diameter : 5.72 mm), and for wire with a specified yield
strength f,, exceeding 410 MPa shall be the stress corresponding to a strain of 0.35 per cent.
eth fy 8 y ponding P
Welded deformed steel wire fabric conforming to ASTM A497 may be used; for a wire with a specified
yield strength ( ie ) exceeding 410 MPa, fy shall be the stress corresponding to a strain of 0.35 per cent.
Welded intersections shall not be spaced farther apart than 400 mm in direction of calculated stress,
except for wire fabric used as stirrups.
b) Plain Reinforcement : Plain reinforcement shall conform to the following BDS and ASTM standards. BDS
1313; ASTM A615M; A616M and A617M. Steel welded wire, fabric plain reinforcement conforming to
ASTM A185 may be used, except that for wire with a specified yield strength f, exceeding 410 MPa, fy
shall be the stress corresponding to a strain of 0.35 per cent. Welded intersections shall not be spaced
farther apart than 300 mm in direction of calculated stress, except for wire fabric used as stirrups.
Smooth steel wire conforming to ASTM A82 may be used in concrete; except that for a wire with a
specified yield strength fy exceeding 410 MPa, fy shall be the stress corresponding to a strain of 0.35
per cent.
c) Cold-worked Steel Reinforcement : Cold-worked steel high strength bars shall conform to IS 1786 : 1985
or BS 4461 : 1978.
d) Bitte Shae : Wire, strands and bars for tendons in prestressed concrete shall conform to BDS :
240, Plain Cold Drawn Steel Wire; ASTM A416, Steel Strand Uncoated Seven-Wire Stress Relieved;
ASTM A421, Uncoated Stress Relieved Steel Wire; and ASTM A722, Uncoated High-Strength Steel Bar.
Wires, strands and bars not specifically listed in the above standards may be used, provided they
conform to minimum requirements of these specifications and do not have properties that make them less
satisfactory than those listed.
e) Structural Steel, Steel Pipe or Tubing : Structural steel used with reinforcing bars in composite
compression members meeting the requirements of the Code shall conform to ‘ASTM A36M, Structural
Steel; ASTM A242M, High Strength Low-Alloy Structural Steel; ASTM A572M, High-Strength Low-
Alloy CohuiabiaineVaradicicn Steel; and ASTM A588M, High-Strength Low-Alloy Structural Steel.
Steel pipe or tubing for composite compression members socspcora of a steel-encased concrete core meetin;
the requirements of this Code shall conform to ASTM A53, re Steel, Black and Hot Dipped Zinc Coated
Welded and Seamless; ASTM A500 Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in
Rounds and Shapes; and ASTM A501, Hot-Formed Welded and Seamless Carbon Steel Structural Tubing.
### 2.4.7 Applicable Standards
terials used in concrete shall comply with the applicable standards listed below.
BDS 279:1963 Specification for Abrasion of Coarse Aggregates by Use of Los Angeles
achine (under revision);
BDS 281:1963 Specification for Organic Impurities in Sands for Concrete (under revision);
BDS 282:1963 Specification for Method of Test for Amount of Materials Finer than
0\. 200 BDS Sieve in Aggregates;
BDS 283:1963 Specification for Method of Test for Soundness of Aggregates by Use of
Sodium Sulphate or Magnesium Sulphate (under revisien:
BDS 284:1963 Specification for Sampling Aggregates for Concrete (under revision);
BDS 285:1963 Aas bgp for Method of Test for Sieve or Screen Analysis of Fine and
oarse Aggregates (under revision);
BDS 921:1980 Specification for Standard Sand for Testing of Cement;
BDS 1044:1983 Methods of Testing Concrete,
Part-1, Methods of Sampling Fresh Concrete;
Part-2, Method of Testing Fresh Concrete;
BDS 240:1963 Specification for Plain Cold Drawn Steel Wire for Prestressed Concrete;
BDS 242:1963 Specification for Tensile Testing of Steel Wire (under revision);
BDS 243:1963 Specification for Coarse and Fine Aggregates from Natural Sources for
concrete;
BDS 244: 1964 Bend Test for Steel (under revision);
ASTM C31-89 Practice for Making and Curing Concrete Test Specimens in the Field;
ASTM C39-86 Test Method for Compressive Strength of Cylindrical Concrete Specimens;
ASTM C42-90 Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of
Concrete;
ASTM C78-84 Test Method for Flexural Strength of Concrete (Using Simple Beam with
Third-Point Loading);
ASTM C94-90 Specification for Ready-Mixed Concrete;
ASTM C172-90 Practice for Sampling Freshly Mixed Concrete;
ASTM C192-90 Practice for Making and Curing Concrete Test Specimens in the
Laboratory.
ASTM C317-91 Specification for Gypsum Concrete;
ASTM C496-90 Test Method for Splitting Tensile Strength of Cylindrical Concrete
; Specimens;
ASTM C617-87 Practice for Capping Cylindrical Concrete Specimens;
ASTM C685-90 eros for Concrete Made by Volumetric Batching and Continuous
ixing;
ASTM C989-89 Specification for Ground Granulated Blast-Furnace Slag for Use in
‘oncrete and Mortars.
### 2.4.8 Concrete Pipe and Precast Sections
Concrete pipes and precast sections shall conform to the standards listed below :
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
C14M-90
C76M-90
C361M-90
C444 M-90
C478M-90
C507 M-90
C654 M-90
C655 M-90
C789 M-90
858-83 (1990)
C913-89
C924 M-89
IS 458-1971
IS 784-1978
IS 1916-1963
IS 3597-1966
IS 4350-1969
IS 7319-1974
IS 7322-1974
### 2.4.9 Asbestos Cement Products
Specification for Concrete Sewer, Storm Drain, and Culvert Pipe;
Specification for Reinforced Concrete Culverts, Storm Drain, and Sewer
Pipe;
Specification for Reinforced Concrete Low-Head Pressure Pipe;
Specification for Perforated Concrete Pipe;
Specification for Precast Reinforced Concrete Manhole Sections;
Specification for Reinforced Concrete Elliptical Culvert, Storm Drain and
Sewer Pipe;
Specification for Porous Concrete Pipe;
Specification for Reinforced Concrete D-Load Culvert, Storm Drain and
Sewer Pipe;
Specification for Precast Reinforced Concrete Box; Sections for Culverts,
Storm Drains, and Sewers;
Underground Precast Concrete Utility Structures; and
Practice for Installation of Underground Precast Concrete Utility
Structures and Testing Concrete Pipe Sewer Lines by Low-Pressure;
Specification for Precast Concrete Water and Wastewater Structures;
Practice for Testing Concrete Pipe Sewer Lines by Low-Pressure Air Test;
Specification for Concrete Pipes (with or without reinforcement) (Second
Revision);
Specification for Prestressed Concrete Pipes (including fittings) (First
Revision);
Specification for Steel Cylinder Reinforced Concrete Pipes;
Methods of Test for Concrete Pipes;
Specifications for Porous Pipes for Underdrainage;
Specification for Perforated Concrete Pipes;
Specification for Specials for Steel Cylinder Reinforced Concrete Pipes.
Asbestos cement products shall conform to the following standards:
BDS
BDS
BDS
BDS
BDS
BDS
ASTM
ASTM
428:1964
429:1964
430:1964
431:1964
579:1966
1046:1983
C222-88
C223-88
Specification for Asbestos Cement Pressure Pipes (under revision);
Specification for Asbestos Cement Building and Sanitary Pipes (under
revision);
Specification for Asbestos Cement Corrugated Sheets for Roofing and
adding (under revision);
Specification for Asymmetrical Section Corrugated Sheets in Asbestos
‘ement for Roofing and Cladding (under revision);
Specification for Asbestos Cement Flat Sheets (under revision);
Specification for Asbestos Cement Products-Corrugated Sheets and Fittings
for Roofing and Cladding;
Specification for Asbestos Cement Roofing Shingles;
Specification for Asbestos Cement Siding;
ASTM C500-88 Test Methods for Asbestos Cement Pipe;
ASTM C508-90 Specification for Asbestos Cement Underdrain Pipe;
ASTM C663-88 Specification for Asbestos Cement Storm Drain Pipe;
ASTM C875-90 Specification for Asbestos Cement Conduit;
ASTM (966-85 Guide for Installing Asbestos Cement Nonpressure Sewer Pipe Lines.
## 2.5 BUILDING LIMES
Building limes shall comply, with the following ASTM standard yrs ASTM C206, Finishing
Hydrated Lime; ASTM C207, Hydrated Lime for Masonry Purposes; ASTM C141, Hydraulic Hydrated Lime
for Structural Purposes; ASTM C977, Quicklime and Hydrated Lime for Soil Stabilization; and ASTM C5,
Quicklime for Structural Purposes.
The following Indian Standards may be accepted for lime concrete and testing of building limes:
IS 2686-1977 ier ein for Cinder Aggregates for Use in Lime Concrete (First
IS 3068-1975 Specification for Broken Brick (burnt clay) Coarse Aggregates for Use in
Lime Concrete (First Revision);
IS 3182-1975 ere for Broken Brick (burnt clay) Fine Aggregates for Use in Lime
IS 1624-1974 Method of Field Testing of Building Lime (First Revision);
IS 3115-1978 Specification for Lime-based Blocks (First Revision);
IS 4139-1976 Specification for Sand-lime Bricks (First Revision);
IS 4098-1983 Specification for Lime-Pozzolana Mixture (First Revision);
IS 10360-1982 Specification for Lime-Pozzolana Concrete Blocks for Paving;
IS 6932 (Parts 1 to X - 1973; Part XI-1983) Method of Tests for Building Limes.
## 2.6 GYPSUM BUILDING MATERIALS AND PLASTER
Gypsum building materials shall conform to the standards listed below.
ASTM (22-91 Specification for Gypsum;
ASTM C28-91 Specification for Gypsum Plasters;
ASTM C35-89 Specification for Inorganic Aggregates for Use in Gypsum Plaster;
ASTM C36-91 "Specification for Gypsum Wallboard;
ASTM C59-91 Specification for Gypsum Casting and Molding Plaster;
ASTM C79-91 Specification for Gypsum Sheathing Board;
ASTM (317-91 Specification for Gypsum Concrete;
ASTM (442-91 Specification for Gypsum Backing Board and Coreboard;
ASTM C471-91 Test Methods for Chemical Analysis of Gypsum and Gypsum Products;
ASTM C472-90 oe for Physical Testing of Gypsum Plasters and Gypsum
ASTM (473-87 hat Methods for Physical Testing of Gypsum Board Products and Gypsum
ASTM (474-89 Test Methods for Testing Joint Treatment Materials for Gypsum Board
Construction;
ASTM C587-91 Specification for Gypsum Veneer Plaster;
ASTM C588-91 Specification for Gypsum Base for Veneer Plasters;
ASTM C630-91 Specification for Water-Resistant Gypsum Backing Board;
ASTM C931-91 Specification for Exterior Gypsum Soffit Board;
ASTM C960-91 Specification for Predecorated Gypsum Board;
IS 2849-1983 Specification for Non-Load Bearing Gypsum Partition Blocks (Solid and
ollow Types) (First Revision).
## 2.7 FLOORING MATERIALS
### 2.7.1 General
Flooring materials are generally of two types; precast systems like tiles, bricks and cast insitu.
### 2.7.2 Concrete/Terrazzo Tiles
Concrete/Terrazzo tiles shall have good abrasion and impact resistance properties. Factors such as the type
of cement and the type and grading of aggregate used influence the resistance of such tiles to chemicals
including cleaning agents. Terrazzo tiles shall have a wear layer after lig at least 6 mm composed of
graded marble es hie in white, tinted or grey Portland cement on a layer of fine concrete. They may be
und after manutacture to expose the marble aggregate and isan noire grouted. a, resisting grits may be
incorporated. These tiles shall conform to BDS : 531-1965, Cement Concrete Flooring Tile (under revision) or
IS: 1337-1980, Specification for Cement Concrete Flooring Tile.
### 2.7.3 Asphalt Tiles/Flooring
Asphalt tiles/floorings are suitable for industrial flooring in areas where they will not be exposed to
solvents, grease, oil, corrosive chemicals and excessive heat. Bitumen mastic for flooring shall conform to IS:
1195-1978; IS : 8374-1977, Bitumen Mastic, Anti-static and Electrically Conducting Grade and IS : 9510-
1980, Bitumen Mastic Acid Resisting Grade.
### 2.7.4 Mosaic Tiles
Mosaic tiles of a variety of shapes and sizes may be used. Thickness of the wear layer is dependent on the
sizes of marble chips but shall not be less than 6 mm thick. The tiles shall be wet cured for sufficient time
before laying so that their surfaces are not damaged during grinding and polishing.
### 2.7.5 Clay Tiles
Clay floor tiles shall have sufficient strength and abrasion resistant characteristics to withstand the impact
and abrasion they are likely to be subject to. When glazed earthenware tiles are used in flooring they shall
conform to IS: :1970, Glazed Earthenware Tiles.
### 2.7.6 Vinyl Tiles
The vinyl tiles shall consist of a ey blended composition of thermoplastic binder, asbestos fibre,
fillers and pigments. The thermoplastic binder shall consist substantially of either or both of the following:
a) vinyl chloride polymer
3 vinyl chloride copolymers.
The polymeric material shall be compounded with suitable plasticizers and stabilizers. The tiles may be
plain, patterned or mottled. The thickness shall not be less than 1.5 mm.
### 2.7.7 Rubber Tiles
These tiles are composed of natural, synthetic or reclaimed rubber, or a combination of these, with
reinforcing fibres, pigments, and fillers, vulcanized and moulded under pressure. The tiles shall have excellent
resilience and resistance to indentation, and good resistance to grease, alkali and abrasion. The thickness
shall not be less than 2 mm.
### 2.7.8 Cast in Situ Floor Coverings
a) Terrazzo : Terrazzo is a marble mosaic with Portland cement matrix and is generally composed of two
parts marble chips to one pat Portland cement. Colour pigments may be added. The thickness of terrazzo
topping may vary from 13mm to 19 mm and may be app! to green concrete of the floor or bonded with
neat Portland cement, or over a sand cushion placed on the concrete floor.
b) Concrete : A concrete topping may be applied to a concrete structural slab before or after the base slab
has hardened. Integral toppings may generally be 25 mm to 40 mm thick; independent toppings about 25
mm to 50 mm thick. Aggregate sizes shall not exceed 6 mm.
### 2.7.9 Other Flooring Materials
Other flooring materials i.e. bricks, natural stone, etc. showing satisfactory performance in similar situations
re allowed. Plastic flooring tile and ceramic unglazed vitreous acid resistant tiles, if used, shall conform
to IS : 3464 and IS : 4357 respectively.
Flooring compositions complying with IS : 657, Materials for Use in the Manufacture of Magnesium
Oxychloride Flooring Composition; and IS: 9197, cd Resin Composition for Floor Topping may be
allowed. Linoleum sheets and tiles shall conform to IS : 653.
## 2.8 TIMBER
Details of the uses of timber in structures or elements of structures including terminology, material
requirements, moisture content pesened cut sizes of sawn timbers, grading, permissible defects, suitability in
respect of durability and treatability, design criteria, and details of joints are given in Chapter 11 of Part 6.
Timber and timber constructions shall satisfy the requirements of that chapter and conform to the following
standards :
BDS 142: 1961 Specification for Wood Doors (under revision);
BDS 173: 1962 Specification for Wood Windows (under revision);
BDS 230: 1962 Glossary of Terms Applicable to Timber, Plywood and Joinery (under
revision);
BDS 803:1973 Trade Names and Abbreviated Symbols for Timber Species;
BDS 819:1975 Code of Practice for Preservation of Timber;
BDS 820:1978 Recommendation for Maximum Permissible Moisture Content of Timber
used for Different Purposes in Bangladesh;
BDS 857:1977 Specification for Grading Rules for Logs and Sawn Timbers;
BDS 1090:1984 Methods of Test for Plywood;
BDS 1256:1990 Classification of Commercial Timber;
BDS 1311:1990 Key for Identification of Commercial Timber.
## 2.9 WOOD PRODUCTS
### 2.9.1 Plywood
Plywood shall conform to the following standards:
BDS 799:1983 Specification for Plywood for General Purposes (First Revision);
BDS 1158:1986 Specification for Veneered Decorative Plywood;
For sampling and testing of Plywood, the following Bangladesh Standards are applicable :
BDS 1087:1984 Specification for Method of Sampling of Plywood :
BDS 1090 : 1984 Methods of Test of Plywood.
IS 4990-1981 : Specifications for Plywood for Concrete Shuttering Work (First Revision);
IS 5509-1980 Specification for Fire Retardant Plywood (First Revision);
IS 5539-1969 Specification for Preservative Treated Plywood.
### 2.9.2 Particle Boards and Fibre Boards
These materials shall conform to the following standards:
BDS ;619:1967 Specification for Particle Board (medium density) (under revision);
BDS 620:1967 Specification for Hardboard (under revision);
ISO 820:1975 Particle Boards—Definition and Classification
ISO 821-1975 Particle Boards—Determination of Dimensions of Test Pieces;
ISO 822:1975 Particle Boards—Determination of Density;
ISO 823:1975 Particle Boards—Determination of Moisture Content;
ISO 766: 1972 Fibre Building Boards—Determination of Dimensions of Test Pieces;
ISO 767:1975 Fibre Building Boards—Determination of Moisture Content;
ISO 768:1972 Fibre Building Boards—Determination of Bending Strength;
ISO 769:1972 Fibre Building Boards—Hard and Medium Boards—Determination of Water
Absorption and of Swelling in Thickness after Immersion in Water;
ISO 818:1975 Fibre Building Boards—Definition-Classification;
ISO 819:1975 Fibre Building Boards Determination of Density;
ISO 2695:1976 Fibre Building Boards—-Hard and Medium Boards for General Purposes-
Quality Specifications-Appearance, Shape and Dimensional Tolerances;
ISO 2696:1976 Fibre Building Boards-Hard and Medium Boards-Quality Specifications-
Water Absorption and Swelling in Thickness;
ISO 3340:1976 Fibre Building Boards-Determination of Sand Content;
ISO 3346:1976 Fibre Building Boards-Determination of Surface Finish (roughness);
ISO 3729:1976 Fibre Building Boards-Determination of Surface Stability;
ISO/TR 7469:1981 Dimensional Stability of Hardboards.
### 2.9.3 Wood based Laminates
Wood based laminates shall conform to the following standards :
IS 3513-1966 Specification for High and Medium Density Wood-based Laminates
(compress);
Part III General Purposes
Part IV Sampling and Tests
IS 9307-1979 (Parts I to VIII) Methods of Tests for Wood-based Structural Sandwich
Construction.
Part I Flexure Test
Part II | Edgewise Compression Test
Part III Flatwise Compression Test
PartIV Shear Test
Part V\_\_\_ Flatwise Tension Test
Part VI\_ Flexure Creep Test
Part VII Cantilever Vibration Test
Part VIII Weathering Test
### 2.9.4 Adhesives and Glue
Adhesives shall conform to the following standards :
IS 848-1974 Specification for Synthetic Resign Adhesives for Plywood (Phenolic and
aminoplastic) (First Revision);
IS 849-1957 Specification for Cold Setting Casein Glue for Wood
IS 851-1978 Specification for Synthetic Resin Adhesives for Construction Work (non
structural) in Wood (First Revision);
IS 852-1969 Specification for Animal Glue for General Wood-Working Purposes (First
Revision);
IS 4835-1979 Specification for Polyvinyl Acetate Dispersion-based Adhesives for Wood
irst Revision);
IS 9188-1979 Specification for Adhesive for Structural Laminated Wood Products for
se Under Exterior Exposure Condition.
## 2.10 DOORS AND WINDOWS
### 2.10.1 Wooden Doors and Window Frames, and Shutters
These shall conform to the following standards:
BDS 142:1961 Specification for Wood Door (under revision);
BDS 173:1962 Specification for Wood Windows (under revision);
BDS 820:1978 Recommendation for Maximum Permissible Moisture Content of Timber
Used for Different Purposes in Bangladesh;
IS 1003-1977/83 Specification for Timber Panelled and Glazed Shutters;
Part I-1977 Door Shutters (Second Revision);
Part II-1983 Window and Ventilator Shutters (Second Revision);
IS 1826-1961 Specification for Venetian Blinds for Windows;
IS 2191-1983 oe for Wooden Flush Door Shutters (cellular and hollow core
e);
art Plywood Face Panels (Fourth Revision);
Part II Particle Board Face Panels and Hardboard Face Panels (Third
Revision);
IS 2202-1983 Specification for Wooden Flush Door Shutters (solid core type);
Part! Plywood Face Panels (Fourth Revision);
Part II Particle Board Face Panels and Hardboard Face Panels (Third
Revision);
IS 4020-1967 Methods of Tests for Wooden Flush Doors : Type Tests;
IS 4121-1983 Specification for Timber Door, Window and Ventilator Frames (Second
Revision);
IS 4962-1968 Specification for Wooden Side Sliding Doors;
IS 6198-1983 > area sag for Ledged, Braced and Battened Timber Door Shutters (First
evision);
### 2.10.2 Metal Door and Window Frames and Shutters
These shall conform to the following standards :
BDS 1270: 1990 Specification for Strong Room Door;
BDS 1273: 1990 Specification for Vault Doors;
IS 1038-1983 Specification for Steel Doors, Windows and Ventilators (Third Revision);
IS’ 1361-1978 Specification for Steel Windows for Industrial Buildings (First Revision);
IS 1948-1961 Specification for Aluminium Doors, Windows and Ventilators;
IS 1949-1961 Specification for Aluminium Windows for Industrial Buildings;
IS 4351-1976 Specification for Steel Door Frames (First Revision);
IS 6248-1979 Specification for Metal Rolling Shutters and Rolling Grills (First
Revision);
IS 7452-1982 Specification for Hot Rolled Steel Sections for Doors, Windows and
entilators (First Revision);
IS 10451-1983 Specification for Steel Sliding Shutters (top hung type);
IS 10521-1983 Specification for Collapsible Gates;
## 2.11 ALUMINIUM AND ALUMINIUM ALLOYS
Aluminium and Aluminium Alloys shall conform to the following standards:
ASTM B26 M-91 Specification for Aluminium-Alloy Sand Castings;
ASTM \_ B85-90 Specification for Aluminium-Alloy Die Castings;
ASTM B108-91 ’ Specification for Aluminium-Alloy Permanent Mold Castings;
ASTM B209 M-90 Specification for Aluminium and Aluminium-Alloy Sheet and Plate;
ASTM B210M-90 Specification for Aluminium and Aluminium-Alloy Drawn Seamless Tubes;
ASTM B211 M-90 Specification for Aluminium and Aluminium-Alloy Bar, Rod and Wire;
ASTM B221 M-90 sg “at for Aluminium and Aluminium-Alloy Extruded Bar, Rods,
ire, Shapes and Tubes;
ASTM B241 M-90 Specification for Aluminium and Aluminium-Alloy Seamless Pipe and
Seamless Extruded Tube;
\| ASTM \_ B308 M-90 Specification for Aluminium-Alloy 6061-T6 Standard Structural Shapes,
Rolled or Extruded;
ASTM B313 M-90 Specification for Aluminium and Aluminium-Alloy Round Welded Tubes;
ASTM B316 M-90 sacar for Aluminium and Aluminium-Alloy Rivet and Cold Heading
ire and Rods;
ASTM B429-90 Specification for Aluminium-Alloy Extruded Structural Pipe and Tube;
ASTM B483 M-90 Specification for Aluminium and Aluminium-Alloy Drawn tubes for
eneral Purpose Applications;
ASTM B547-90 Specification for Aluminium and Aluminium-Alloy Formed and Arc-Welded
Round Tube;
ASTM B632 M-90\_ . Specification for Aluminium Alloy Rolled Tread Plate;
ASTM B745 M-90 Specification for Corrugated Aluminium Pipe for Sewers and Drains;
ASTM E34-88 = Methods for Chemical Analysis of Aluminium and Aluminium Base
Alloys.
## 2.12 BUILDERS HARDWARE
The applicable standards are listed below :
BDS 113:1986 Specification for Latches and Locks for Doors in Buildings;
IS 204-78 Specification for Tower Bolts;
Part I Ferrous Metals (Fourth Revision);
Part If Nonferrous metals (Fourth Revision);
IS 205-1978 Specification for Nonferrous Metal Butt Hinges (Third Revision);
IS 206-1981 Specification for Tee and Strap Hinges (Third Revision);
IS 208-1979 Specification for Door Handles (Third Revision);
IS 281-1973 Specification for Mild Steel Sliding Door Bolts for Use with Padlock
( nd Revision);
IS 362-1982 Specification for Parliament Hinges (Fourth Revision);
IS 363-1976 Specification for Hasps and Staples (Third Revision);
IS 364-1970 Specification for Fanlight Catch (Second Revision);
IS 452-1973 Specification for Door Springs, Rat-tail Type (Second Revision);
IS 453-1973 Specification for Double Acting Spring Hinges (Second Revision);
IS\_ 729-1979 Specification for Drawer Locks, Cupboard Locks and Box Locks (Third
Revision);
IS 1019-1974 Specification for Rim Latches (Second Revision);
IS 1341-1981 Specification for Steel Butt Hinges (Fourth Revision);
\| IS 1823-1980 Specification for Floor Door Stoppers (Third Revision);
i
IS 1837-1966 Specification for Fanlight Pivots (First Revision);
IS 2209-1976 Specification for Mortice Locks (vertical type) (Third Revision);
IS 2681-1979 Specification for Nonferrous Metal Sliding Door Bolts for Use with
Padlocks (Second Revision);
IS 3564-1975 Specification for Door Closers (hydraulically regulated) (Second
Revision);
IS 3818-1971 Specification for Continuous (piano) Hinges (First Revision);
IS 3828-1966 Specification for Ventilator Chains;
IS 3843-1966 Specification for Steel Backflap Hinges;
IS 3847-1966 Specification for Mortice Night Latches;
IS 4621-1975 Specification for Indicating Bolts for use in Public Baths and Lavatories
(First Revision);
IS 4948-1974 Specification for Welded Steel Wire Fabric for General Use (First
Revision);
IS 4992-1975 Specification for Door Handles for Mortice Locks (vertical type) (First
Revision);
IS 5187-1972 Specification for Flush Bolts (First Revision);
IS 5899-1970 Specification for Bathroom Latches;
IS 5930-1970 Specification for Mortice Latch (vertical type);
IS 6315-1971 Specification for Floor Springs (hydraulically regulated) for Heavy Doors;
IS 6318-1971 Specification for Plastic Window Stays and Fasteners;
IS 6343-1982 Specification for Door Closers (pneumatically regulated) for Light Doors
Weighing up to 40 kg (First Revision);
IS 6602-1972 Specification for Ventilator Poles;
IS 6607-1972 Specification for Rebated Mortice Locks (vertical type);
IS 7196-1974 Specification for Hold Fast;
IS 7197-1974 Specification for Double Action Floor Springs (without oil check) for
Heavy Doors;
IS 7534-1974 Specification for Mild Steel Locking Bolts with Holes for Padlocks;
IS 7540-1974 Specification for Mortice Dead Locks;
IS 8756-1978 Specification for Ball Catches for use in Wooden Almirah;
IS 8760-1978 Specification for Mortice Sliding Door Locks, with Lever Mechanism;
IS 9106-1979 Specification for Rising Butt Hinges;
IS 9131-1979 Specification for Rim Locks;
IS 9460-1980 Specification for Flush Drop Handle for Drawer;
IS 9899-1981 Specification for Hat, Coat and Wardrobe Hooks;
IS 10019-1981 Specification for Steel Window Stays and Fasteners;
IS 10090-1982 Specification for Numericals;
IS 10342-1982 Specification for Curtain Rail System.
## 2.13 ROOF COVERINGS
### 2.13.1 Scope
The provisions of this section shall govern the materials used for roof coverings.
### 2.13.2 Compatibility of Materials
All roofs and roof coverings shall be of materials that are compatible with each other and with the building
or structure to which the materials are applied.
### 2.13.3 Material Specifications and Physical Characteristics
All materials to be used in the construction of roofs and roof coverings shall conform to the applicable
standards listed in this section. In the absence of applicable standards or when materials are of questionable
suitability, testing by an approved testing agency may be required by the building official to determine the
character, quality and limitations of use of the materials.
### 2.13.4 Weather Protection
All roofs shall be covered with approved roof coverings properly secured to the building or structure to
resist wind and rain. Roof coverings shall be designed, totalled and maintained in accordance with
approved manufacturer's recommendations such that the roof covering shall serve to protect the building or
structure.
### 2.13.5 Wind Resistance
All roofs and roof coverings shall be secured in place to the building or structure to withstand the wind
loads.
### 2.13.6 Structural and Construction Loads
The structural roof components shall be capable of mapparting the roof covering system and the material and
equipment loads that will be encountered during installation of the roof covering system.
### 2.13.7 Impact Resistance
Roof coverings shall resist impact damage based on the results of tests conducted in accordance with ASTM
D4272 or D3746.
### 2.13.8 Metal-sheet Roof Coverings
Metal-sheet roof coverings installed over structural aang and decking shall comply with BDS 868,
Galvanized Corrugated Sheet Roof and Wall Coverings; BDS 1122, Hot-dip Galvainzed Steel Sheet and Coil;
ASTM A361, A755 or B 101. Metal-sheet roof coverings shall be installed in accordance with approved
manufacturer's installation instructions.
### 2.13.9 Asbestos Sheet Roof Covering
Asbestos sheets used for roof coverings shall comply with BDS 430, Asbestos Cement Corrugated Sheets for
Roofing and Cladding; BDS 431, Asymmetrical Section Corrugated Sheets in Asbestos Cement Roofing and
Cladding; BDS 579, Abestos Cement Flat Sheets; BDS 1046, Asbestos Cement Products-Corrugated Sheets and
Fittings for Roofing and Cladding.
### 2.13.10 Interlocking Clay or Cement Tile
Interlocking clay or cement tile shall be installed only over solid sheathing or spaced structural sheathing
boards. Interlockin clay or cement tile shall not be installed on roof slopes below one unit vertical in 3 units
horizontal (1:3). Horizontal battens shall be required on roof slopes over one unit vertical in 2 units
horizontal (1:2). Single layer underlayment is required over solid sheathing on all roof slopes. Reinforced
underlayment shall be required when spaced sheathing is used. Regardless of roof slope, the first three tile
courses and all tiles within 900 mm of roof edges, tiles at changes in roof slope or changes in slope direction,
shall be fastened to the roof. For the field of the roof, fastening is not required on roof slopes below one unit
vertical in 2 units horizontal (1:2). Every other tile course shall be fastened on roof slopes 1:2 to less than
1:1; and every tile shall be fastened on roof slopes 1:1 and over. Tile overlap shall be in accordance with
approved manufacturer's installation instructions.
### 2.13.11 Non-interlocking Clay or Cement Tile
Non-interlocking clay or cement tile shall not be installed on roof slopes below one unit vertical in 5 units
horizontal (1:5). Double layer underlayment is required on roof slopes below one unit vertical in 4\_ units
horizontal (1:4). Single layer underlayment is required on all other roof slopes. Non-interlocking clay or
cement tile shall be secured to the roof with two fasteners per tile. The minimum tile overlap shall be 75 mm.
### 2.13.12 Roof Insulation
Rigid combustible roof insulation shall be cate provided the insulation is covered with approved roof
coverings directly applied thereto. Insitu lime concrete may be used on flat roofs of buildings. Minimum
compacted thickness of such a layer shall be 75 mm and have adequate slope for drainage. The materials used
in lime concrete shall conform to the standards specified in Sec 2.5 of this Part.
### 2.13.13 Recovering and Replacement of Roof Coverings
New roof coverings shall not be installed without first removing existing roof coverings when the existing
roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering
is not acceptable as a base for additional roofing.
### 2.13.14 Reuse of Materials
Slate, clay or cement tile shall be permitted for reuse, except that damaged, cracked or broken slate or
tile shall not be reused. Existing vent flashings, metal edgings, drain outlets, collars and metal counter
flashings shall not be reused where rusted, damaged or deteriorated. Aggregate surfacing materials shall not
be reused.
### 2.13.15 Applicable Standards
The applicable standards for materials used in roofs and roof coverings are listed below:
BDS 430:1964
BDS 431:1964
BDS 579:1966
BDS 868:1978
BDS
BDS
ASTM
1046:1983
1122:1985
A361/A
361M - 85 (1990)
ASTM A755/A755M-89
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
B101-83 (1988)
C222-88
C836-89
C 95 -87
C1029-90
D224-89
D225-86
D226-89
D227-89
D249-89
D312-89
D371-89
D450-78 (1984)
D1227-87
D1863-86
D2178-89
Specification for Asbestos Cement Corrugated Sheets for Roofing and
adding (under revision);
Specification for Asymmetrical Section Corrugated Sheets in Asbestos
Cament for Roofing and Cladding (under revision);
Specification for Asbestos Cement Flat Sheets (under revision);
Code of Practice for Galvanized Corrugated Sheet Roof and Wall
Coverings;
Specification for Asbestos Cement Products - Corrugated Sheets and
ittings for Roofing and Cladding;
Specification for Hot-dip Galvanized Steel and Coil.
Specification for Steel Sheet, Zinc-Coated (Galvanized) by
the Hot-dip Process for Roofing and Siding;
Specification for Steel Sheet, Metallic Coated by the Hot-dip Process and
Prepainted by the Coil-Coating Process for Exterior Exposed Building
Products;
Specification for Lead-Coated Copper Sheets;
Specification for Asbestos-Cement Roofing Shingles;
Specification for Roofing Slate;
Specification for High Solids Content, Cold Liquid-Applied Elastomeric
aterproofing Membrane for Use With Separate Wearing Course;
Specification for High-Solids Content, Cold Liquid-Applied Elastomeric
aterproofing Membrane With Integral Wearing Surface;
Specification for Spray-Applied Rigid Cellular Polyurethane Thermal
Insulation;
Specification for Smooth-Surfaced Asphalt Roll Roofing (Organic Felt);
Specification for Asphalt Shingles (Organic Felt) Surfaced with Mineral
ranules;
Specification for Asphalt-Saturated Organic Felt Used in Roofing and
aterproofing; C
Specification for Coal-Tar-Saturated Organic Felt Used in Roofing and
aterproofing;
Specification for Asphalt Roll Roofing (Organic Felt) Surfaced with
ineral Granules;
Specification for Asphalt Used in Roofing;
Specification for Asphalt Roll Roofing (Organic Felt) Surfaced with
ineral Granules; Wide Selvage;
Specification for Coal - Tar Pitch Used in Roofing, Dampproofing, and
aterproofing;
Specification for Emulsified Asphalt Used as a Protective Coating for
Roofing;
Specification for Mineral Aggregate Used on Built-Up Roofs;
Specification for Asphalt Glass Felt Used in Roofing and Waterproofing;
ASTM D2626-86 Specification for Asphalt-Saturated and Coated Organic Felt Base Sheet
Used in Roofing;
ASTM D2898-81 (1986) Methods for Accelerated Weathering on Fire-Retardant-Treated Wood for
Fire Testing;
ASTM D3161-81 (1986) Test Method for Wind-Resistance of Asphalt Shingles;
ASTM D3672-86 Specification for Venting Asphalt-Saturated and Coated Inorganic Felt
Base Sheet Used in Roofing;
ASTM D3747-85 Test Method for Impact Resistance of Bituminous Roofing Systems;
ASTM D3909-86 S ag for Asphalt Roll Roofing (Glass Felt) Surfaced with Mineral
ranules;
ASTM D4272-90 Test Method for Total Energy Impact of Plastic Films by Dart Drop;
ASTM D4434-87 Specification for Poly (Vinyl Chloride) Sheet Roofing;
ASTM D4601-86 Specification for Asphalt-Coated Glass Fibre Base Sheet Used in Roofing;
ASTM D4637-87 Specification for Vulcanized Rubber Sheet Used in Single-Ply Roof
lembrane;
ASTM E108-90 Test Method for Fire Tests of Roof Coverings;
ASTM E838-81 Practice for Pasioseine Accelerated Outdoor Weathering Using
Concentrated Natural Sunlight;
ASTM G23-90 Practice for bo Light-Exposure Apparatus (Carbon-Arc Type) With
and Without Water for Exposure of Nonmetallic Materials;
ASTM G26-90 Practice for rating Light-Exposure Apparatus (Xenon-Arc Type) With
and Without Water for Exposure of Nonmetallic Materials;
ASTM G53-88 Practice for Operating Light- and Water-Exposure Apparatus (Fluorescent
UV-Condensation Type) for Exposure of Nonmetallic Materials;
RMA (Rubber Manufacturer Association, USA) RP - 4 - 88
Wind Design Guide for Ballasted Single-Ply Roofing Systems;
SPRI (Single Ply Roofing Institute, USA) - 86
Wind Design Guide for Ballasted Single-Ply Roofing Systems;
FM ( Factory Manual) 4450 - 89
Standard Laboratories Department Approved Standard for Class I
Insulated Steel Deck Roofs;
FM 447 -86 Approval Standard for Class I Roof Coverings;
CGSB (Canadian General Standards Board) 37 - GP - 56M - 80
Membrane, Modified Bituminous, Prefabricated, and Reinforced for
Roofing;
## 2.14 PAINTS AND VARNISHES
### 2.14.1 Water Based Paints
Water based paints shall conform to the following standards:
BDS 500:1965 Specification for Distemper Dry (under revision);
BDS 1097:1984 Specification for Plastic Emulsion Paint.
Part I for Interior Use;
Part 2 for Exterior Use;
IS 5410-1969 Specification for Cement Paint, Colour as Required;
IS 428-1969 : Specification for Distemper, Oil Emulsion, Colour as Required
### 2.14.2 Ready Mixed Paint and Enamels
Ready mixed paints and enamels shall conform to the following standards:
BDS 13:1960 Specification for Ready Mixed Paints, Varnish, Lacquers and Related
Products (under revision);
BDS 14:1960 Specification for Black Bituminous Paint, Brushing for General Purposes
(under revision);
BDS 397:1964 Specification for Ready Mixed Paint, Brushing, Red Oxide Zinc Chrome,
Priming (under revision);
BDS 398:1964 Specification for Ready Mixed Paint, Spraying, Red Oxide Zinc Chrome,
Priming (under revision);
BDS 399:1964 Specification for Aluminum Paint, Spraying for General Purposes, in Dual
ontainer (under revision);
BDS 400:1964 Fe ara for Aluminium Paint, Brushing, for General Purposes in Dual
‘ontainer (under revision);
BDS 401:1964 potatoes for Varnish, Finishing, Exterior, Type-I, (Synthetic)
(Tentative) (under revision);
BDS 402:1989 psig ead for Ready Mixed Paint, Brushing, Finishing, Semigloss, for
eral Purposes (First Revision);
BDS 499:1965 Specification for Ready Mixed Paints, Brushing, for Road Marking (white,
yellow and black) (under revision);
BDS 616:1966 Specification for Enamel, Brushing, Exterior (i) Undercoating, (ii)
Finishing, Colour as Required (under revision);
BDS 617:1966 Specification for Enamel, Brushing, Interior (i) Undercoating, (ii) Finishing,
‘olour as Required (under revision);
BDS 926:1980 Specification for Ready Mixed Paint, Brushing, Petrol Resisting, Air
rying, for Exterior Painting of Containers, Colour as Required;
BDS 927:1980 Specification for Ready Mixed Paint, Brushing, Petrol Resisting, Air
ing, for Interior Painting of Tanks and Containers, Red Oxide (colour
unspecified);
BDS 928:1980 Specification for Ready Mixed Paint, Brushing, Acid Resisting, for
Protection Against Acid Fumes, Colour as Required;
BDS 973:1981 Specification for Specification and Methods of Test for Linseed Stand Oil
for Paints and Varnishes;
BDS 974:1981 Specification and Methods of Test for Raw Tung Oils for Paints and
arnishes; ‘
BDS 1005:1981 Specification for Ready Mixed Paint, Brushing, Finishing, Stoving, Enamel,
olour as Required;
BDS 1141:1986 Specification for Ready Mixed Aluminium Priming Paints for Woodwork;
BDS 1151:1986 Specification for Pavement Marking Paints.
### 2.14.3 Thinners and Solvents
These shall conform to the following standards:
IS 324-1959 Specification for Ordinary Denatured Spirit (revised);
IS 533-1973 Specification for Gum Spirit of Turpentine (Oil of Turpentine) (First
Revision);
IS 82-1973 Methods of Sampling and Test for Thinners and Solvents for Paints (First
Revision). .
### 2.14.4 Varnishes and Lacquers
These materials shall conform to the following standards:
BDS
BDS
BDS
BDS
IS
Is
Is
Is
Is
401:1964
1064:1983
1065:1983
1066:1983
340-1978
347-1975
Specification for Varnish, Finishing, Exterior, Type-I, (synthetic) (under
revision);
Specification for Varnish, Stoving;
Specification for Varnish, Acid Resisting;
Specification for Varnish, Finishing, Interior;
Methods of sampling and Test for Varnishes and Lacquers (First Revision);
Specification for Varnish, Mixing (First Revision);
Specification for Varnish, Spirit, Clear, Hard;
Specification for Varnish, Shellac for general purposes (First Revision);
Specification for French Polish (First Revision);
## 2.15 SANITARY APPLIANCES AND FITTINGS
### 2.15.1 Sanitary Appliances
Sanitary appliances shall conform to the following standards:
BDS
BDS
1162: 1987
1163 : 1987
ASHRA E90A-80
ASHRA \_ E 90B-75
AWWA \_ 700-77
AWWA \_C701-78
AWWA C702-78
AWWA C702-78
BS
BS
BS
BS
BS
1125: 1987
1244
1254:1981
1329:1974
1876: 1992 (1977)
### 2.15.2 Pipes and Pipe Fittings for Water Supply and Sanitation
Pipes and pipe fittings
BDS
BDS
BDS
BDS
BDS
428:1964
429:1964
1111:1984
1356:1972
1357: 1972
‘
Specification for Ceramic Wash Basins and Pedestals;
Leap for Vitreous Sanitary Appliances,
art-1, General Requirements;
Part-2, Specific Requirements for Water Closets;
Part-3, Specification Requirements for Urinal (Bowl type);
Part-4, Specific Requirements for Foot Rest;
Part-5, Specific Requirements for Integrated Squatting Pans.
Energy Conservation in New Building Design;
Energy Conservation in New Building Design;
Cold Water Meter Displacement Type;
Cold Water Meter Turbine Type Class-I;
Cold Water Meter Turbine Type Class-II;
Cold Water Meter Compound Type,
Specification for WC Flushing Cisterns (Including Dual Flash Cisterns and
ush Pipes);
Metal Sink for Domestic Purposes;
Specification for C Seats (Plastics);
Specification for Metal Hand Rinse Basins;
Specification for Automatic Flushing Cistern for Urinals
s for Water Supply and Sanitation
‘or water supply and sanitation shall comply with the following standards.
Specification for Asbestos Cement Pressure Pipe;
Specification for Asbestos Cement Building and Sanitary Pipes (under
revision);
Centrifugally Cast (spun) Iron Pressure Pipes for Water, Gas and Sewage;
Specification for Ferrules for Water Services;
Specification for Washers with Fittings for Water Service;
ASTM A53-90 Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated Welded
and Seamless;
ASTM A74-87 Specification for Cast Iron Soil Pipe and Fittings
ASTM A377-89 Index of Specification for Ductile-Iron Pressure Pipe;
ASTM B42-89 Specification for Seamless Copper Pipe, Standard Sizes;
ASTM B43-91 Specification for Seamless Red Brass Pipe, Standard Sizes;
ASTM B75M-90 Specification for Seamless Copper Tube;
ASTM B88M-89 Specification for Seamless Copper Water Tube;
ASTM B251M-88 Specification for General Requirements for Wrought Seamless Copper and
Copper-Alloy Tube;
ASTM B302-1988 Specification for Threadless Copper Pipe;
ASTM B306-1988 Specification for Copper Drainage Tube (DWV);
ASTM \_ B429-1990 Specification for Aluminium-Alloy Extruded Structural Pipe and Tube;
ASTM B447-1989 Specification for Welded Copper Tube;
ASTM B745/B745M-1990 \_ Specification for Corrugated Aluminium Pipe for Sewers and Drains;
ASTM C4-62 (1986) Specification for Clay Drain Tile;
ASTM C14M-90 Specification for Concrete Sewer, Storm Drain, and Culvert Pipe;
ASTM C76M-90 a for Reinforced Concrete Culvert, Storm Drain, and Sewer
ASTM C508-90 Specification for Asbestos-Cement Underdrain Pipe;
ASTM C654M-90 Specification for Porous Concrete Pipe;
ASTM (700-89 Specification for Vitrified Clay Pipe, Extra Strength, Standard Strength,
and Perforated;
ASTM D1527-89 Specification for Acrylonitrile-Butadience-Styrene (ABS) Plastic Pipe,
Schedules 40 and 80;
ASTM D1785-91 ne ea for Poly (Vinyl chloride) (PVC) Plastic pipe, Schedules 40, 80
ASTM D1861-88 Specification for Homogeneous Bituminized Fibre Drain and Sewer Pipe;
ASTM D1862-88 Specification for Laminated-Wall Bituminized Fibre Drain and Sewer Pipe;
ASTM D2239-89 Specification for Polyethylene (PE) Plastic pipe (SIDR-PR) Based on
ontrolled Inside Diameter;
ASTM D2241-89 a for Poly (Vinyl Chloride) (PVC) Pressure-Rated Pipe (SDR
Ties);
ASTM D2282-89 cea for Acrylonitrile-Butadiene-Styrene (ABS) Plastic Pipe (SDR-
ASTM D2311-88 Specification for Perforated, Homogeneous Bituminized Fibre Pipe for
eneral Drainage;
ASTM D2321-89 Practice for Underground Installation of Thermoplastic Pipe for Sewers
and Other Gravity-flow Applications;
ASTM D2464-91 Specification for Threaded Poly Vinyl Chloride (PVC) Plastic Pipe Fittings,
Schedule 80;
ASTM D2466-90 Specification for Poly Vinyl Chloride (PVC) Plastic Pipe Fittings,
schedule 40;
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
IS 404 (Part-I)-1977
ISO
D2467-90
D2609-90
D2661-91
D262-89
D2665-91
D2666-89
D2672-89
D2729-89
D2737-89
D2751-91
D2846-90
D2949-89
D3034-89
D3309-89
F405-89
F409-91
F437-89
F438-90
F439-90
F441-89
F442-89
F628-91
F891-1991
160: 1980
ISO 392:1986
ISO 881:1980
Spetication for Socket-Type Poly (Vinyl Chloride) (PVC) Plastic Pipe
ittings, Schedule 80;
Specification of Plastic Insert Fittings for Polyethylene (PE) Plastic Pipe;
Specification for Acrylonitrile-Butadiene-Styrene (ABS) Schedule 40
Plastic Drain, Waste, and Vent Pipe;
Specification for Polybutylene (PB) Plastic Pipe (SIDR-PR) Based on
controlled Inside Diameter;
Specification for Poly (Vinyl Chloride) (PVC) Plastic Drain, Waste and
ent Pipe and Fittings;
Specification for Polybutylene (PB) Plastic Tubing;
Specification for Joints for IPS PVC Pipe Using Solvent cement;
Specification for Poly (Vinyl Chloride) (PVC) Sewer Pipe and Fittings;
Specification for Polyethylene (PE) Plastic Tubing;
Specification for Acrylonitrile-Butadiene-Styrene (ABS) Sewer Pipe and
ittings;” 2
Specification for Chlorinated Poly (Vinyl Chloride) (CPVC) Plastic Hot-
and Cold-Water Distribution system;
Specification for 82 mm (3.25-in) Outside Diameter Poly (Vinyl Chloride)
(Pvc) Plastic Drain, Waste, and Vent Pipe and Fittings;
Specification for Type PSM Poly (Vinyl Chloride) (PVC) Sewer Pipe and
ittings;
specication for Polybutylene (PB) Plastic Hot and Cold-Water
istribution Systems;
Specification for Corrugated Polyethylene (PE) Tubing and Fittings;
ot age a for Thermoplastic Accessible and Replaceable Tube and
‘ubular Fittings;
apr ook for Threaded Chlorinated Poly (Vinyl Chloride) (CPVC)
Plastic Pipe Fittings, Schedule 80;
Specification for Socket-Type Chlorinated Poly (Vinyl Chloride) (CPVC)
lastic Pipe Fittings, Schedule 40;
Specification for Socket-Type Chlorinated Poly (Vinyl Chloride) (CPVC)
Plastic Pipe Fittings, Sch le 80;
Specification for Chlorinated Poly (Vinyl Chloride) (CPVC) Plastic Pipe
Schedule 40 and 80;
Specification for Chlorinated Poly Vinyl Chloride (CPVC) Plastic Pipe
@DR-PR);
Specification for Acrylonitrile-Butadiene-Styrene (ABS) Schedule 40
Plastic Drain, Waste, and Vent Pipe With a Cellular Core;
Specification for Coextruded Poly Vinyl Chloride (PVC) Plastic Pipe with
a Cellular Core;
Specification for Lead Pipes Part I for other than Chemical Purpose (Second
Revision);
Asbestos-Cement Pressure Pipes and Joints;
Asbestos-Cement Pipe Fittings for Building and Sanitary Purposes;
Asbestos-Cement Pipes, Joints and Fittings for Sewerage and Drainage;
ISO 2531-1991 Ductile Iron Pipes, Fittings and Accessories for Pressure Pipelines;
ASME/ANSI\_ B16.3-85 Malleable Iron Threaded Fittings;
ASME/ANSI B16.485 Cast Iron Threaded Fittings;
ASME/ANSI\_ B16.9-86 Factory Made Wrought Steel Buttwelding Fittings;
ASME/ANSI\_ B16.11-80 Forged Steel Fittings, Socket-Welding and Threaded;
ASME/ABSI\_ B16.12-83 Cast-Iron Threaded Drainage Fittings;
ASME/ANSI B16.15-85 Cast Bronze Threaded Fittings;
ASME/ANSI B16.18-84 Cast Copper Alloy Solder Joint Pressure Fittings;
ASME/ANSI B16.22-89 Wrought Copper and Copper Alloy Solder Joint Pressure Fittings;
ASME/ANSI\_ B16.23-84 Cast Copper Alloy Solder Joint Drainage Fittings (DWV);
ASME/ANSI B16.28-86 Wrought Steel Buttwelding Short radius Elbows and Returns;
ASME/ANSI\_ B16.29-86 Wrought Copper and Wrought Copper Alloy Solder Joint Fittings for
sovent Drainage Systems;
ASME/ANSI B16.32-84 Cast Copper Alloy Solder Joint Fittings for Sovent Drainage Systems;
AWWA 110-87 picinicnag for Grey Iron and Ductile Iron pine gg 76 mm to 1220 mm (3 in.
‘ough 48 inches), for Water and Other Liquids.
### 2.15.3 Joints and Connections Between Pipes and Fittings
Applicable standards for joints and connections between pipes and fittings are listed below:
ASTM \_B42-89 Specification for Seamless Copper Pipe, Standard Sizes;
ASTM (425-90 Specification for Compression Joints for Vitrified Clay Pipe and Fittings;
ASTM C443M-85(1990) Specification for Joints for Circular Concrete Sewer and Culvert Pipe,
sing Rubber Gaskets;
ASTM C564-88 Specification for Rubber Gaskets for Cast Iron Soil Pipe and Fittings;
ASTM D1869-78 (1984) Specification for Rubber Rings for Asbestos Cement Pipe;
ASTM D2235-88 Speacnion for Solvent Cement for Acrylonitrile-Butadiene-Styrene
(ABS) Plastic Pipe and Fittings;
ASTM D2564-91 Specification for Solvent Cements for Poly Vinyl Chloride (PVC) Plastic
Pipe and Fittings;
ASTM D2657-90 Practice for Heat-Joining Polyolefin Pipe and Fittings;
ASTM D2661-91 Specification for acrylonitrile-Butadiene-Styrene (ABS) Schedule 40
Plastic Drain, Waste and Vent Pipe;
ASTM D2846-90 Specification for Chlorinated Poly (Vinyl Chloride) (CPVC) Plastic Hot-
and Cold-Water Distribution systems;
ASTM D2855-90 Practice for Making Solvent-Cemented Joints with Poly (Vinyl Chloride)
, (PVC) Pipe and Fittings;
ASTM D3139-89 Specification for Joints for Plastic Pressure Pipes Using Flexible
Elastometric Seals;
ASTM D3140-90 Practice for Flaring Polyolefin Pipe and Tubing;
ASTM D3212-89 Specification for Joints for Drain and Sewer Plastic Pipes Using Flexible
lastomeric Seals;
ASTM D3309-89 Specification for Polybutylene (PB) Plastic Hot and Cold-Water
Distribution Systems;
ASTM F402-88 Practice for Safe ee Solvent Cements, Primers, and Cleaners Used
for Joining Thermoplastic Pipe and Fittings;
ASTM F493-89 Poway Pe for Solvent cements for Chlorinated Poly (Vinyl Chloride)
(CPVC) Plastic Pipe and Fittings;
ASTM F628-91 Specification for Acrylonitrile-Butadiene-Styrene (ABS) Schedule 40
Plastic Drain, Waste, and vent Pipe with a Cellular Core;
ASTM F656-89 Specification for Primers for Use in Solvent Cement Joints of Poly (Vinyl
loride) (PVC) Plastic Pipe and Fittings;
ASME/ANSI B1.20.1 Malleable Iron Threaded Fittings.
### 2.15.4 Taps and Valves
Taps and valves shall conform to the following standards :
BS 1212 3 (Parts) Specification for Float Operated Valves (excluding floats);
BS 1010 Specification for Draw-Off Taps and Stopvalves for Water Services;
BS 1968 Specification for Floats for Ball Valves (copper);
BS 5433: 1976 Specification for Underground Stopvalves for Water Services (copper);
BS 2456: 1973 Specification for Floats for Ball Valves (plastic) for Cold and Hot Water
BS 1415 (2 parts) Mixing Valves (Manullay Operated);
BS 5163: 1986 Specification for Predominantly Key-Operated Cast Iron Wedge Gate
alve for Water Works;
BS 3377:1985 Specification for Boilers for Use with Domestic Solid Mineral Fuel
' Appliances;
BS 843: 1976 Specification for Thermal Storage Electric Water Heaters;
BS 855:1976 Sh pala emis for Welded Steel Boilers for Central Heating and Indirect Hot
ater Supply.
## 2.16 MISCELLANEOUS MATERIALS
### 2.16.1 Ferrocement
Details including material requirements are given in Chapter 12 of Part 6.
### 2.16.2 Plastics
Plastics may be used in buildings or structures as light transmitting materials such as glazing, skylights,
tighting lenses, luminous ceilings, roof panels, signs and similar purposes. Foam plastics are also used in
buildings.
et Sei for aeppor st of a plastic material shall furnish all necessary technical data required by the
Building Official. The data shall include chemical composition; applicable physical, sechaziical and thermal
properties such as fire resistance, flammability and flame spread; weather resistance; electrical properties;
products of combustion; and coefficient of expansion.
The requirements for light transmitting plastics, including roof panels and foam plastics are given below.
#### 2.16.2.1 Light Transmitting Plastics
An approved light transmitting plastic shall be any thermoplastic,
thermosetting or reinforced thermosetting plastic material which has a self-ignition temperature of 343°C or
greater when tested in accordance with ASTM D1929, Test Method for Ignition Properties of Plastics; a
smoke density rating not greater than 450 when tested in the manner intended for use in accordance with
ASTM E84, Test Method for Surface Burning Characteristics of Building Materials; or not greater than 75
when tested in the thickness intended for use in accordance with ASTM 2843, Test Method for Density of
Smoke from the Burning or Decomposition of Plastics; and which conforms to one of the following
combustibility classifications:
Class C1: Plastic materials which have a burning extent of 25 mm or less when tested at a nominal thickness
of 1.5 mm, or in the thickness intended for use, in accordance with ASTM D635, Test Method for Rate of
Burning and/or Extent and Time of Burning of Self-Supporting Plastics in Horizontal Position; or
Class C2: Plastic materials which have a burning rate of 63 mm/min or less when tested at a nominal
thickness of 1.5 mm, or in the thickness intended for use, in accordance with ASTM D635.
#### 2.16.2.2 Foam Plastics
All foam plastics and foam plastic cores of manufactured assemblies shall have a
flame spread rating of not more than 75 and shall have a smoke Sri rating of not more than 450 when
tested in the maximum thickness intended for use in accordance with E84.
All foam plastics, unless otherwise indicated in this section, shall be separated from the interior of a buildin
by an approved thermal barrier of 13 mm gypsum wall board or equivalent thermal barrier material whi
will limit the average temperature rise of the unexposed surface to not more than 121°C after 15 minutes of
fire exposure complying with the standard time-temperature curve of ASTM E119, Test Methods for Fire
Tests of Building Construction and Materials. The thermal barrier shall be installed in such a manner that it
will stay in place for a minimum of 15 minutes under the same testing conditions. The thermal barrier is not
required when the foam plastic is protected by a 25 mm minimum thickness of masonry or concrete.
#### 2.16.2.3 Applicable Standards
Alist of applicable standards for plastics is given below:
BDS 885:1979 Method for Measuring Viscosity Number and K-Value of PVC Resins;
BDS 886:1978 Method for Direct Measuring the Specific Gravity of Plastics;
BDS 887:1978 Method for Measuring Deformation under Heat of Flexible Rigid PVC
Compounds;
BDS 888:1978 Method for Measuring Temperature of Deflection under Load;
BDS 889:1978 Method for Measuring the Vicat Softening Temperature (VST) of
Thermoplastics;
BDS 890:1978 Method for Measuring the Water Absorption at Room Temperature and
Bolling Water Absorption of Plastics;
BDS 891:1978 Method for Measuring the Flexural Modulus of Plastics;
BDS 892:1978 Method for Measuring the Resistance to Tear Propagation of Flexible
Plastics, Film or Sheeting;
ASTM D543-87 Test Method for Resistance of Plastics to Chemical Reagents;
ASTM D568-77(1985) Test Method for Rate of Burning and/or Extent and Time of Burning of
Flexible Plastics in a Vertical Position;
ASTM D635-88 Test Method for Rate of Burning and/or Extent of Time of Burning of Self
Supporting Plastics in a Horizontal Position;
ASTM D638-90 Test Method for Tensile Properties of Plastics;
ASTM D695M-90 Test Method for Compression Properties of Rigid Plastics;
ASTM D882-90 Test Methods for Tensile Properties of Thin Plastic Sheeting;
ASTM D1003-61(1988) oe for Haze and Luminous Transmittance of Transparent
ASTM D1044-90 Test Method for Resistance of Transparent Plastics to Surface Abrasion;
ASTM D1204-84 Test Method for Linear Dimensional Changes of Nonrigid Thermoplastic
; Sheeting or Film at Elevated Temperature;
ASTM D1242-87 Test Methods for Resistance of Plastic Materials to Abrasion;
ASTM D1593-89 Specification for Non rigid Vinyl Chloride Plastic Sheeting;
ASTM D1925-70(1988) Test Method for Yellowness Index of Plastics;
ASTM D1927-81(1988) Specification for Rigid Poly (Vinyl Chloride) Plastic Sheet;
ASTM D1929-91 Test Method for Ignition Properties of Plastics;
ASTM D2103-86 Specification for Polyethylene Film and Sheeting;
ssn Sahn area anneinehervaiinnen ns
ASTM D2126-87 Test Method for Response of Rigid Cellular Plastics to Thermal and Humid
Aging:
ASTM D2842-69(1988) Test Method for Water Absorption of Rigid Cellular Plastics;
ASTM D2843-77(1988) noe for Density of Smoke from the Burning or Decomposition of
ASTM D3293-90 Specification for PTFE Resin Molded Sheet;
ASTM D3678-88 Ferg for Rigid Poly (Vinyl Chloride) (PVC) Interior-Profile
ASTM D3679-91 Specification for Rigid Poly (Vinyl Chloride(PVC) Siding;
ASTM D3841-88 Specification for Glass-Fibre-Reinforced Polyester Plastic Panels;
ASTM D4802-88 Specification for Poly (Methyl Methacrylate)Acrylic Plastic Sheet;
ASTM E84-91 Test Method for Surface Burning Characteristics of Building Materials;
ASTM E119-88 Test Methods for Fire Tests of Building Construction and Materials.
### 2.16.3 Ballies and Wood Poles
Ballies of Sal/Gazari, Sundari and Garjan are used in building construction. These shall be free from rots,
knots and sap, and straight and uniform in size. These should conform to the following standards:
BDS 809:1973 ers for Wood Poles for Overhead Power and Telecommunication
ines;
ASTM D25-91 Specification for Round Timber Piles;
IS 3337:1978 Specification for Ballies for General Purposes (First Revision);
IS 1900:1974 Method of Testing Wood Poles;
IS 6711:1972 Code of Practice for Maintenance of Wood Poles for Overhead Power and
Telecommunications Lines.
### 2.16.4 Bamboos
The following standards shall be applicable for bamboos used for structural and nonstructural purposes:
IS 1902:1961 Code of Practice for Preservation of Bamboo and Cane for Non-structural
Purposes;
IS 6874:1973 Method of Tests for Round Bamboos;
IS 8242:1976 Methods of Tests for Split Bamboo;
IS 8295:1976 Specification for Bamboo Chicks, Part I Fine;
IS 9096:1979 Code of Practice for Preservation of Bamboos for Structural Purposes.
### 2.16.5 Fillers, Stoppers and Putties
These shall conform to the following standards:
IS 110:1968 Specification for pia? A Mixed Paint, Brushing, Grey Filler, for Enamels,
or Use Over Primers (First Revision);
IS 345:1952 Specification for Wood Filler, Transparent, Liquid;
IS 419:1967 Specification for Putty for Use on Window Frames (First Revision);
IS 421:1953 Specification for Jointing Paste, for Bedding Moldings on Coaching Stock;
IS 423:1961 Specification for Plastic Wood, for Joiners’ Filler (revised);
IS 424:1965 Specification for Plastic Asphalt (revised);
IS 3709:1966 Specification for Mastic Cement for Bedding of Metal Windows;
IS 7164:1973 Specification for Stopper.
### 2.16.6 Wire Ropes and Wire Products
These materials shall conform to the following standards:
ASTM A116-88 So Sd for Zinc-Coated (Galvanized) Steel Woven Wire Fence
ASTM A121-86 Specification for Zinc-Coated (Galvanized) Steel Barbed Wire;
ASTM A368-82(1987) Specification for Stainless and Heat-Resisting Steel Wire Strand;
ASTM A392-91 Specification for Zinc-Coated Steel Chain-Link Fence Fabric;
ASTM A475-89 Specification for Zinc-Coated Steel Wire Strand;
ASTM A492-82(1987) Specification for Stainless and Heat -Resisting Steel Rope Wire;
ASTM AS510-91 Specification for General Requirements for Wire Rods and Coarse Round
ire, Carbon Steel;
ASTM A585-86 Specification for Aluminium Coated Steel Barbed Wire;
ASTM A586-86(1991) aerate for Zinc-Coated Parallel and Helical Steel Wire Structural
ASTM A603-88 Specification for Zinc-Coated Steel Structural Wire Rope;
ASTM A817-91 Specification for Metallic-Coated Steel Wire for Chain Link Fence Fabric;
ASTM A824-91 Specification for Metallic-Coated Steel Marcelled Tension Wire for Use
with Chain Link Fence.
ASTM F1183-88 Specification for Aluminium-Alloy Chain Link Fence Fabric;
IS 2365:1977 Specification for Steel Wire Suspension Ropes for Lifts, Elevators and
oists (First Revision).
### 2.16.7 Waterproofing and Damp-proofing Materials
Waterproofing and damp-proofing materials shall conform to the following standards:
ASTM D41-85 Specification for Asphalt Primer Used in Roofing, Damp-proofing and
aterproofing;
ASTM D43-73(1988) Specification for Creosote Primer Used in Roofing, Damp-proofing and
aterproofing; ,
ASTM D146-90 Test methods of Sampling and Testing Bitumen Saturated Felts and Woven
Fabrics for Roofing and Waterproofing;
ASTM D173-73 Specification for Bitumen-Saturated Cotton Fabrics Used in Roofing and
aterproofing;
ASTM D 224-89 Specification for Smooth-Surfaced Asphalt Roll Roofing (Organic Felt);
ASTM D226-89 Specification for Asphalt-Saturated Organic Felt Used in Roofing and
aterproofing;
ASTM D227-89 Specification for Coal-Tar-Saturated Organic Felt Used in Roofing and
aterproofing;
ASTM D 249-89 Specification for Asphalt Roll Roofing (Organic Felt) Surfaced with
ineral Granules;
ASTM D250-88 Specification for Asphalt-Saturated Asbestos Felt Used in Roofing and
aterproofing;
ASTM D312-89 Specification of Asphalt Used in Roofing;
ASTM D 449-89 Specification for Asphalt Used in Damp-proofing and Waterproofing;
ASTM D450-78 aioe for Coal-Tar Pitch Used in Roofing, Damp-proofing and
aterproofing;
ASTM D1327-86 Specification for Bitumen-Saturated Woven Burlap Fabrics Used in
Roofing and Waterproofing;
ASTM D1668-86 Specification for Glass Fabrics (Woven and Treated) for Roofing and
aterproofing;
ASTM D2178-89 Specification for Asphalt Glass Felt Used in Roofing and Waterproofing;
ASTM D2626-86 4 ea for Asphalt-Saturated and Coated Organic Felt Base Sheet
sed in Roofing;
ASTM D3468-90 Specification for Liquid-Applied Neoprene and Chlorosulfonated
Polyethylene Used in Roofing and Waterproofing.
### 2.16.8 Glazed Tiles and Tile-setting Mortars
Glazed tiles shall conform to the following standards:
BDS 1301:1990 Specification for Glazed Earthenware Wall Tiles;
ASTM C126 - 86 Specification for Ceramic Glazed Structural Clay Facing Tile, Facing Brick
and Solid Masonry Units;
ANSI A137.1 Specification for Ceramic Tile;
BS 6431 Part 1 to Part 23 Ceramic Floor and Wall Tiles.
#### 2.16.8.1 Mortars for Ceramic Wall and Floor Tile
a)
b)
°)
d)
e)
h)
i)
Portland Cement Mortars: Portland cement mortars for installing ceramic wall and floor tile shall
comply with ANSI A108.1 and be of the compositions indicated in Table 5.2.1.
Dry-set Portland Cement Mortars: Premixed prepared Portland cement mortars, which require only the
addition of water and which are used in the installation of ceramic tile, shall comply with ANSI A 118 1
The shear bond strength for tile set in such mortar shall be as required in accordance with that standard.
Tile set in dry-set Portland cement mortar shall be installed in accordance with ANSI A 108.5.
Electrically Conductive Dry-Set Mortars: Premixed prepared Portland cement mortars, which require
only the addition of water and which comply with ANSI A118.2, shall be used in the installation of
electrically conductive ceramic tile. Tile set in electrically conductive dry-set mortar shall be installed in
accordance with ANSI A 108.7.
Latex-modified Portland Cement Mortars: Latex-modified Portland cement thin set mortars in which
Lalex is added to dry-set mortar as a replacement for all or part of the pauging water which are used for
the installation of ceramic tile shall comply with ANSI A 118.4. Tile set in latex-modified Portland
cement mortar shall be installed in accordance with ANSI A 108.5.
Epoxy Mortar: Chemical-resistant epoxy for setting and grouting ceramic tile shall comply with ANSI A
118.3. Tile set and grouted with epoxy shall be installed in accordance with ANSI A 108.6.
Furan Mortar and Grout: Chemical resistant furan mortar and grout which are used to install ceramic
tile shall rt with ANSI A 118.5. Tile set and grouted with furan shall be installed in accordance
with ANSI A 108.8
Modified Epoxy-Emulsion Mortar and Grout: Modified ee psig a mortar and grout which are
used to install ceramic tile shall comply with ANSI A 118.8. Tile set and grouted with modified epoxy-
emulsion mortar and grout shall be installed in accordance with ANSI A 108.9.
Organic Adhesives: Water-resistant organic adhesives used for the installation of ceramic tile shall
comply with ANSI A 136.1. The shear bond strength after water immersion shal] not be less than 0.25
kN/mmé? for Type I adhesive, and not less than 0.13 KN/mm? for Type Il adhesive when tested in
accordance with ANSI A 136.1. Tile set in organic adhesive shall be installed in accordance with ANSI
A 108.4.
Portland Cement Grouts: Portland cement grouts used for the installation of ceramic tile shall comply
with ANSI A 118.6. Portland cement grouts for tilework shall be installed in accordance with ANSI A
108.10.
ae Applicable Standards: A list of applicable standards for tiles, mortars and adhesives is given
elow.
BDS
1301 : 1990 Specification for Glazed Earthenware Wall Tiles;
ASTM (C126 - 86 Specification for Ceramic Glazed Structural Clay Facing Tile, Facing Brick
and Solid Masonry Units;
ANSI A108.1-85 Specification for the Installation of Ceramic Tile with Portland Cement
ortar;
ANSI A108.4-85 Installation of Ceramic Tile with Organic Adhesives or Water Cleanable
Tile Setting Epoxy Adhesive; ‘
ANSI A108.5-85 Installation of Ceramic Tile with Dry-Set Portland Cement Mortar or
Latex-Portland Cement Mortar;
ANSI A108.6-85 Installation of Ceramic Tile with Chemical Resistant, Water Cleanable Tile
Setting and Grouting Epoxy;
ANSI A108.7-85 Specification for Electrically Conductive Ceramic Tile Installed with
onductive Dry-Set Portland Cement Mortar;
ANSI A108.8-85 ee of Ceramic Tile with Chemical Resistant Furan Mortar and
rout;
ANSI A108.9-85 Installation of Ceramic Tile with Modified Epoxy Emulsion
Mortar/Grout;
ANSI A108.10-85 Installation of Grout in Tilework;
ANSI A118.1-85 Specification for Dry-Set Portland Cement Mortar;
ANSI A118.2-85 Specifications for Conductive Dry-set Portland Cement Mortar;
ANSI = A118.3-85 Specifications for Chemical Resistant Water Cleanable Tile Setting and
routing Epoxy and Water Cleanable Tile Setting Epoxy Adhesive;
ANSI A118.4-85 Specifications Furan Latex - Portland Cement Mortar;
ANSI A118.5-85 Specifications for Chemical Resistant Furan;
ANSI . A118.6-85 Specifications for Ceramic Tile Grouts;
ANSI A118.8-85 Specifications for Modified Epoxy Emulsion Mortar/Grout;
ANSI A136.1-85 Organic Adhesives for Installation of Ceramic Tile;
ANSI —\_A137.1-88 Specifications for Ceramic Tile;
BS 6431 Floor and Wall Tiles;
BS 6431 Part 1 1983 Specification for Classification and Making, Including Definitions and
aracteristics;
BS 6431 Part 2.1984 Specification for Extruded Ceramic Tiles with Low Water Absorption (E\<3%) Group A1;
BS 6431 Part 3 Extruded Ceramic Tiles with a Water Absorption of 3% \< 6%. Group A
lla;
BS 6431 Part 3
Section 3.1 1986 Specification for General Products;
BS 6481 Part 3 ;
Section 3.2 1986 Specification for Products Terre Cuite, Cotto, Baldosion Catalan;
BS 6431 Part 4 Extruded Ceramic Tiles with a Water Absorption of 6% \ 10%, Group A111;
Specification for Dust-prestressed Ceramic Tiles with a Low-Water
Absorption (E\<3%) Group B1;
Specification for Dust-prestressed Ceramic Tiles with a Water Absorption
of 3% \10%. Group B111;
Method for Determination of Dimensions and Surface Quality;
Method for Determination of Water Absorption;
Method for Determination of Modulus of;
Method for Determination of Scratch Hardness of Surface According to
Mhos;
Method for Determination of Resistance to Abrasion of Unglazed Tiles;
Method for Determination of Linear Thermal Expansion;
Method for Determination of Resistance to Thermal Shock;
Method for Determination of Crazing Resistance-Glazed Tiles;
Method for Determination of Chemical Resistance-Unglazed Tiles;
Method for Determination of Chemical Resistance-Unglazed Tiles;
Method for Determination of Resistance to Surface Abrasion-Glazed
Tiles;
Specification for Sampling and Basis for Acceptance;
Refractories shall conform to the following standards:
Iso
IsO
Iso
IsO
IsO
ISO
Iso
IsO
ISO
Iso
528:1983
1109:1975
1146:1988
1893:1989
1927:1984
2245:1990
2477:1987
2478:1987
3187:1989
5013:1985
Refractory Products-Determination of Pyrometric Cone Equivalent
(refractoriness);
Refractory Products-Classification of Dense Shaped Refractory Products;
Pyrometric Reference Cones for Laboratory Use-Specification;
Refractory Products-Determination of Refractoriness-Under-Load
(differential with rising temperature);
Prepared Unshaped Refractory Materials (Dense and Insulating)
Classification;
Shaped Insulating Refractory Products-Classification;
ISO 2477:1987 Shaped Insulating Refractory Products-Determination of Permanent Change
in Dimensions on Heating;
Dense Shaped Refractory Products-Determination of Permanent Change in
Dimensions on Heating;
Refractory Products-Determination of Creep in Compression;
Refractory Products-Determination of Modulus of Rupture at Elevated
Temperatures;
ISO
IsO
IsO
IsO
IsO
ISO
IsO
IsO
ISO
IsO
ISO
IsO
IsO
Iso
ISO
IsO
ISO
IsO
ISO
### 2.16.10 Thermal Insulating Materials
5014:1986
5016:1986
5017:1988
5018:1983
5019-1:1984
5019-2:1984
5019-3:1984
5419-4:1988
5015-6:1984
5022:1979
8656:1988
8840:1987
8890:1988
8894-1:1987
8894-2:1990
8895:1986
9205:1988
10080:1990
10081:1991
Refractory Products-Determination of Modulus of Rupture at Ambient
Temperature;
Shaped Insulating Refractory Products-Determination of Bulk Density and
True Porosity;
Dense Shaped Refractory Products-Determination of Bulk Density,
Apparent Porosity and True Porosity;
Refractory Materials-Determination of True Density;
Refractory Bricks-Dimensions-Part I: Rectangular Bricks;
Refractory Bricks-Dimensions-Part 2: Arch Bricks;
Refractory Bricks-Dimensions-Part 3: Rectangular Checker Bricks for
Regenerative Furnace;
a sig Bricks-Dimensions-Part 4: Dome Bricks for Electric arc Furnace
OOIS;
Refractory Bricks-Dimensions-Part 6: Basic Bricks for Oxygen Steel
Making Converters;
Shaped Refractory Products-Sampling and Acceptance Testing;
Refractory Bricks for Use in Rotary Kilns-Dimensions;
Refractory Products-Sampling of Raw Materials and Unshaped Products;
Part 1; Sampling Scheme;
Refractory Materials-Determination of Bulk Density of Granular
Materials (Grain Density);
Dense Shaped Refractory Products-Determination of Resistance to Sulfuric. \_
Acid;
Refractory Materials-Determination of Thermal Conductivity-
Part 1: Hot-Wire Method (Cross-Array);
Refractory Materials-Determination of Thermal Conductivity-
Part 2: Hot-Wire Method (Parallel);
Shaped Insulating Refractory Products-Determination of Cold Crushing
Strength;
Refractory Bricks for Use in Rotary Kilns-Hot-face Identification
Marking;
Refractory Products-Classification of Dense, Shaped Acid-Resisting
Products; :
Basic Refractory Products-Classification-Part I: Products Containing Less
Than 7% Residual Carbon.
Thermal insulation may be in the following physical forms:
Loose fill dry
granules or nodules poured or below in place;
Flexible or semi rigid blankets and bolts of wool like material;
Rigid boards and blocks;
Membrane reflective insulation;
Spray applied mineral fibre or insulating concrete;
Poured in plain-insulating concrete;
Foamed in place-polyurethane;
Gypsum plaster.
Thermal insulating materials shall conform to the standards listed below.
ASTM C167-90
Test Methods for Thickness and Density of Blanket or Batt Thermal
Insulations;
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
ASTM
C177-85
C195-90
C196-87
C208-72 (1982)
C209-84
C236-89
C240-91
C335-89
411-82 (1987)
C449 /C449M-88S
516-80 (1990)
C518-91
520-81 (1985)
533-85 (1990)
547-77
549-81 (1986)
553-70 (1977)
591-85
610-85
C665-88
C726-88
C739-91
Test Method for Steady-State Heat Flux Measurements and Thermal
Transmission Properties by Means of the Guarded Hot plate Apparatus;
Specification for Mineral Fibre Thermal Insulating Cement;
ee for Expanded or Exfoliated Vermiculite Thermal Insulating
Specification for Insulating Board (Cellulose Fibre), Structural and
ecorative;
Methods of Testing Insulating Board (Cellulose Fibre), Structural and
Decorative;
Test Method of Steady-State Thermal Performance of Building Assemblies
by Means of a Guarded Hot Box;
Test Methods of Testing Cellular Glass Insulation Block;
Test Method for Steady-State Heat Transfer Properties of Horizontal Pipe
Insulation;
Test Method for Hot-Surface Performance of High-Temperature Thermal
Insulation;
Specification for Mineral Fibre Hydraulic-Setting Thermal Insulating and
inishing Cement;
Specification for Vermiculite Loose Fill Thermal Insulation;
Test Method for Steady-State Heat Flux Measurements and Thermal
Transmission Properties by Means of the Heat Flow Meter Apparatus;
Test Methods for Density of Granular Loose Fill Insulations;
Specification for Structural Insulating Formboard (Cellulosic Fibre);
Specification for Calcium Silicate Block and Pipe Thermal Insulation;
Specification for Preformed Flexible Elastomeric Cellular Thermal
Insulation in Sheet and Tubular Form;
Specification for Mineral Fibre Preformed Pipe Insulation;
Specification of Perlite Loose Fill Insulation;
Specification for Cellular Glass Thermal Insulation;
—— for Mineral Fibre Blanket and Felt Insulation (Industrial
ype);
Specification for Preformed Cellular Polystyrene Thermal Insulation;
Specification for Unfaced Preformed Rigid Cellular Polyurethane Thermal
Insulation;
Specification for Mineral Fibre Blanket Insulation and Blanket-Type
Insulation (Metal Mesh Covered);
Specification for Expanded Perlite Block and Pipe Thermal Insulation;
Specification for Mineral Fibre Block and Board Thermal Insulation;
Specification for Mineral-Fibre Blanket Thermal Insulation for Light
‘rame Construction and Manufactured Housing;
Specification for Mineral Fibre Roof Insulation Board;
Specification for Perlite Thermal Insulation Board;
Specification for Cellulosic Fibre (Wood-Base) Loose Fill Thermal
Insulation;
:
ASTM C764-91 Specification for Mineral Fibre Loose-Fill Thermal Insulation;
ASTM (916-85 (1990) Specification for Adhesives for Duct Thermal Insulation;
ASTM C984-83 Specification for Perlite Board and Rigid Cellular Polyurethane Composite
oof Insulation;
ASTM C991-90 Specification for Flexible Glass Fibre Insulation for Pre-Engineered Metal
Buildings;
ASTM C1013-85 Specification for Membrane-Faced Rigid Cellular Polyurethane Roof
Insulation;
ASTM C1014-88 Specification for Spray-Applied Mineral Fibre Thermal or Acoustical
Insulation;
ASTM C1029-90 Specification for Spray-Applied Rigid Cellular Polyurethane Thermal
‘ Insulation;
ASTM C1050-91 Specification for Rigid Cellular Polystyrene-Cellulosic Fibre Composite
Roof Insulation;
ASTM (1071-86 Specification for Thermal and Acoustical Insulation (Mineral Fibre Duct
Lining Material).
### 2.16.11 Screw Threads and Rivets
These shall conform to the following standards :
IS 554:1975 Dimensions for Pipe Threads where Pressure Tight Joints are Required on
the Threads (Second Revision);
IS 1929:1982 Specification for Hot Forged Steel Rivets for Hot Closing (12 to 36 mm
diameter) (First Revision);
IS 2155:1982 —— for Cold-Forged Solid Steel Rivets for Hot Closing (6 to 16 mm
ameter) (First Revision);
IS 2643:1975 Dimensions for Pipe Threads for Fastening Purposes;
Part I - Basic Profile and Dimensions (First Revision);
Part II - Tolerances (First Revision);
Part III - Limits of Sizes;
IS 2907:1964 Specification for Non-ferrous Rivets (1.6 mm to 10 mm)
IS 2998:1981 Specification for Cold Forged Steel Rivets for Cold Closing (1 to 16 mm
diameter) (First Revision);
IS 10102:1982 Technical supply conditions for Rivets.
### 2.16.12 Sealants
* Sealants shall conform to the following standards:
ASTM C 509-90 S rN a for Elastomeric Céllular Preformed Gasket and Sealing
aterial;
ASTM C542-90 Specification for Lock-Strip Gaskets;
ASTM (C564-88 Specification for Rubber Gaskets for Cast Iron Soil Pipe and Fittings;
ASTM = (C570-72(1989) Specification for Oil-and-Resin-Base Caulking Compound for Building
‘onstruction;
ASTM (C716-87 Specification for Installing Lock-Strip Gaskets and Infill Glazing
aterials;
ASTM (719-86 Test Method for Adhesion and Cohesion of Elastomeric Joint Sealants
Under Cyclic Movement (Hockman Cycle);
ASTM C790-90 Guide for Use of Latex Sealants;
ASTM (C794-80 (1986) Test Method for Adhesion-in-Peel of Elastomeric Joint Sealants;
ASTM C804-83 (1988) Practices for Use of Solvent-Release Type Sealants;
ASTM (834-76 (1986) Specification for Latex Sealing Compounds;
ASTM C864-90 Specification for Dense Elastomeric Compression Seal Gaskets, Setting
Blocks, and Spacers;
ASTM (919-84 (1988) Practice of Use of Sealants in Acoustical Applications;
ASTM (920-87 Specification for Elastomeric Joint Sealants;
ASTM (C962-86 Guide for Use of Elastameric Joint Sealants;
ASTM D2628-91 Specification for Preformed Polycholoroprene Elastomeric Joint Seals for
‘oncrete Pavements;
ASTM D3405-78 Specification for Joint Sealants, Hot-Poured, for Concrete and Asphalt
Pavements;
ASTM D3406-85 Specification for Joint-Sealant, Hot-Applied, Elastomeric-Type, for
Portland Cement Concrete pavement ;
ASTM D3667-85 (1990) Specification for Rubber Seals Used in Flat-Plate Solar Collectors;
ASTM D3771-85 (1990) Specification for Rubber Seals Used in Concentrating Solar Collectors;
ASTM D3832-79 (1987) Specification for Rubber Seals Contacting Liquids in Solar Energy Systems;
ISO 3934:1978 Rubber Building Gaskets-Materials in Preformed Solid Vulcanizates Used
for Sealing Glazing and Panels-Specification;
ISO 4633:1983 Rubber Seals-Joint gy for Water Supply, Drainage and Sewerage
Pipelines-Specifications for Materials;
ISO 4635:1982 Rubber, Vulcanized-Preformed Compression Seals for Use Between
Concrete Motorway Paving Sections-Specifications for Material;
ISO 5892:1981 Rubber Building Gaskets-Materials for Preformed Solid Vulcanized
Structural Gaskets-Specification;
ISO 6447:1991 Rubber Seals-Joint een Used for Gas Supply Pipes and Fittings-
Specification for Material;
ISO 9331:1991 Rubber Seals Joint Rings for Hot Water Supply Pipelines up to 110°C
Specifications for the Material.
### 2.16.13 Joints and Jointing Products -
Joints and jointing products shall conform to the following standards :
ISO 2444 : 1988 Joints in Buildings-Vocabulary;
ISO 3867:1982 Agglomerated Cork-Material of Expansion Joints for Construction and
Building Test-Methods;
ISO 3869:1981 sh heey mam Cork-Filler Material of Expansion Joints for Construction
and Buildings -Characteristics, Sampling and Packing;
ISO 3934:1978 Rubber Building Gaskets-Materials in Preformed Solid Vulcanizates Used
for Sealing Glazing and Panels-Specification;
ISO 4633:1983 Rubber Seals-Joint Rings for Water Supply, Drainage and Sewerage
Pipelines-Specification for Materials;
ISO 4635:1982 Rubber, Vulcanized-Preformed Compression Seals for Use Between
Concrete Motorway Paving Sections-Specification for Material;
ISO 5892:1981 Rubber Building Gaskets-Materials for Preformed Solid Vulcanized
Structural Gaskets-Specification;
ISO 6447:1983 Rubber Seals-Joint = Used for Gas Supply Pipes and Fittings-
Specification for Material
7
ISO 6589:1983 Joints in Building-Laboratory Method of Test for Air Permeability of
Joints;
ISO 7389:1987 Building Construction-Jointing Products-Determination of Elastic
Recovery;
ISO 7390:1987 + ne Construction-Jointing Products-Determination of Resistance to
low;
ISO 7727:1984 Joints in Buildin, -Principles for Jointing of Building Components-
Accommodation of Dimensional Deviations Burin ig, Construction;
ISO 8339:1984 Building Construction-Jointing Products-Sealants-Determination of Tensile
Properties;
ISO 8340:1984 Building Construction-Jointing Products-Sealants-Determination of Tensile
Properties at Maintained Extension;
ISO 8394:1988 Building Construction-Jointing Products-Determination of Extrudability of
One-Component Sealants;
ISO 9046:1987 Building Construction-Sealants-Determination of Adhesion/ Cohesion
Properties at Constant Temperature;
ISO 9047:1989 Building Construction-Sealants-Determination of Adhesion/ Cohesion
Properties at Variable Temperatures;
ISO 9631:1991 Rubber Seals-Joint Rings for Hot Water Supply Pipelines up to 110°C
Specifications for the Material;
ISO 10563:1991 Building Construction-Sealants for Joints-Determination of Change in
Mass and Volume;
IsO 10590:1991 Building Construction-Sealants-Determination of Adhesion/Cohesion
Properties at Maintained Extension after Immersion in Water;
ISO: 1059T 21991: Building Construction-Sealants-Determination of Adhesion/Cohesion
Properties after Immersion in Water.
### 2.16.14 Glass and Glazing
The applicable standards for glass and glazing are listed below :
ASTM C1036-90 Specification for Flat Glass;
ASTM C1044-90 Specification of Heat-Treated Flast Glass Kind HS, Kind FT Coated and
ncoated Glass;
ANSI Z 97.1 Safety Performance Specifications and Methods of Tests for Transport
Safety Glazing Materials Used in Building;
CPSC \_16‘CFR Safety Standard for’Architectural Glazing Materials.
Part 1201A
## 2.17 CGI SHEET ROOFING AND WALLING
Galvanized corrugated steel sheets conforming to BDS 868, Galvanized Corrugated Sheet Roof and Wall
Coverings, may be used over structural framing for construction of roofs and walls. Requirements for various
roofing materials including CGI sheet have been specified in Sec 2.13 above.
# Part V: Building Materials
Source: https://docs.sayed.app/bnbc2006/part-5-building-materials/index
Scope, definitions, and standards for building materials.
Part 5 covers the scope and definitions for building materials, and material-specific requirements and standards.
## Chapters
Scope and definitions for building materials.
Requirements and standards for individual building materials.
# Appendices A-E
Source: https://docs.sayed.app/bnbc2006/part-6-structural-design/appendices
Appendix A: Conversion of Expressions from SI to FPS Units; Appendix B: Methods of Soil Exploration and Sampling; Appendix C: Guidelines for Computing the Column Interaction Diagrams; Appendix D: Calculation of Volume Fraction of Reinforcement; Appendix E: Common Types and Sizes of Steel Meshes used in Ferrocement
## Appendix A: Conversion of Expressions from SI to FPS Units
This appendix provides the FPS equivalents of selected empirical expressions and equations presented in SI units in Part 6 of the Code. It may be noted that the computed values obtained from an SI expression and its FPS equivalent given in this Appendix may show some differences, which may be due to rounding off of the constants within these expressions. However, these differences, if any, may be only minor, and the FPS equivalent expressions are intended to serve as references only.
### Chapter 2
The following units are applicable to the corresponding variables in the expressions provided below.
| Quantity | SI Unit | FPS Unit |
| ----------------------------------- | ------- | -------- |
| Length, height, other dimensions | m | ft |
| Area | m² | ft² |
| Weight, loads, force (axial, shear) | kN | lb |
| Pressure, stress | kN/m² | psf |
| Speed, velocity | km/h | miles/h |
| Section/Table | SI | FPS Equivalent |
| ---------------------- | ------------------------------------------------ | --------------------------------------------- |
| Table 6.2.7 | $R = 0.6 + \sqrt{8/A_t}$ | $R = 0.6 + \sqrt{86/A_t}$ |
| | $R = 0.25 + \sqrt{14/A_t}$ | $R = 0.25 + \sqrt{151/A_t}$ |
| 2.4.6 | $C_c = 47.2 \times 10^{-6}$ | $C_c = 62.5 \times 10^{-4}$ |
| | $\bar{f} = \dfrac{55.44fh}{sV_b}$ | $\bar{f} = \dfrac{10.5fh}{sV_b}$ |
| | $T_I = \dfrac{2.35\sqrt{D_o}}{(h/13.72)^\alpha}$ | $T_I = \dfrac{2.35\sqrt{D_o}}{(h/45)^\alpha}$ |
| | $k = 0.0065$ | $k = 0.002$ |
| | $k = 0.00328$ | $k = 0.001$ |
| Table 6.2.12 | $1.0/h$ | $3.28/h$ |
| | $0.07/h$ | $0.23/h$ |
| | $0.0061/h$ | $0.02/h$ |
| Tables 6.2.16 & 6.2.19 | $D\sqrt{q_z} > 0.167$ | $D\sqrt{q_z} > 2.5$ |
| 2.5.6 | $C_t = 0.083$ | $C_t = 0.035$ |
| | $= 0.073$ | $= 0.030$ |
| | $= 0.049$ | $= 0.020$ |
| | $C_t = 0.031/\sqrt{A_c}$ | $C_t = 0.1/\sqrt{A_c}$ |
### Chapter 4
The following units are applicable to the corresponding variables in the expressions provided below.
| Quantity | SI Unit | FPS Unit |
| -------------------------------------------------- | ------- | -------- |
| Length, other dimensions | mm | in |
| Area | mm² | in² |
| Moment of inertia | mm⁴ | in⁴ |
| Force (axial, shear) | N | lb |
| Moment, torsion | N·mm | lb-in |
| Stress, strength | N/mm² | psi |
| Modulus of elasticity, shear modulus of elasticity | N/mm² | psi |
| Section/Table | SI | FPS Equivalent |
| ------------- | -------------------------------------------------------- | ------------------------------------------------------- |
| 4.3.5 | $F_v = 0.083\sqrt{f_m'} \leq 0.25$ | $F_v = 1.0\sqrt{f_m'} \leq 36$ |
| | $F_v = 0.25\sqrt{f_m'} \leq 0.75$ | $F_v = 3.0\sqrt{f_m'} \leq 110$ |
| | $F_v = 0.025\sqrt{f_m'} \leq 0.40$ | $F_v = 0.3\sqrt{f_m'} \leq 60$ |
| Table 6.4.4 | $\dfrac{1}{36}\left(4 - \dfrac{M}{Vd}\right)\sqrt{f_m'}$ | $\dfrac{1}{3}\left(4 - \dfrac{M}{Vd}\right)\sqrt{f_m'}$ |
| | $\left(0.4 - 0.2\dfrac{M}{Vd}\right)$ | $\left(60 - 30\dfrac{M}{Vd}\right)$ |
| | $0.083\sqrt{f_m'}$ | $1.0\sqrt{f_m'}$ |
| | $\dfrac{1}{24}\left(4 - \dfrac{M}{Vd}\right)\sqrt{f_m'}$ | $\dfrac{1}{2}\left(4 - \dfrac{M}{Vd}\right)\sqrt{f_m'}$ |
| | $\left(0.6 - 0.2\dfrac{M}{Vd}\right)$ | $\left(90 - 30\dfrac{M}{Vd}\right)$ |
| | $0.125\sqrt{f_m'}$ | $1.5\sqrt{f_m'}$ |
| 4.3.9 | $B_v = 1070(f_m'A_b)^{1/4}$ | $B_v = 350(f_m'A_b)^{1/4}$ |
| | $B_t = 0.04A_p\sqrt{f_m'}$ | $B_t = 0.5A_p\sqrt{f_m'}$ |
| 4.6.6 | $l_d = 0.29d_bf_s$ | $l_d = 0.002d_bf_s$ |
| | $l_d = 0.22d_bf_s$ | $l_d = 0.0015d_bf_s$ |
| Table 6.4.13 | $0.17\sqrt{f_m'} \leq 0.65$ | $2\sqrt{f_m'} \leq 95$ |
| | $0.33\sqrt{f_m'} \leq 1.2$ | $4\sqrt{f_m'} \leq 175$ |
| | $0.21\sqrt{f_m'} \leq 0.65$ | $2.5\sqrt{f_m'} \leq 95$ |
| | $V_m = 0.083C_dA_{mv}\sqrt{f_m'}$ | $V_m = C_dA_{mv}\sqrt{f_m'}$ |
### Chapter 5
The following units are applicable to the corresponding variables in the expressions provided below.
| Quantity | SI Unit | FPS Unit |
| ------------------------ | ------- | -------- |
| Length, other dimensions | mm | in |
| Area | mm² | in² |
| Unit weight | kN/m³ | lb/ft³ |
| Stress, strength | N/mm² | psi |
| Modulus of elasticity | N/mm² | psi |
| Section/Table | SI | FPS Equivalent |
| ------------- | ------------------------------ | ------------------------------ |
| 5.6.2 | $f_{cr}' = f_c' + 2.33s - 3.5$ | $f_{cr}' = f_c' + 2.33s - 500$ |
| | $f_c' + 7.0$ | $f_c' + 1000$ |
| | $f_c' + 8.5$ | $f_c' + 1200$ |
| | $f_c' + 10.0$ | $f_c' + 1400$ |
| | $44w_c^{1.5}\sqrt{f_c'}$ | $33w_c^{1.5}\sqrt{f_c'}$ |
| | $4700\sqrt{f_c'}$ | $57000\sqrt{f_c'}$ |
| | $3750\sqrt{f_c'}$ | $45000\sqrt{f_c'}$ |
### Chapter 6
The following units are applicable to the corresponding variables in the expressions provided below.
| Quantity | SI Unit | FPS Unit |
| -------------------------------------------------- | ------- | -------- |
| Length, other dimensions | mm | in |
| Area | mm² | in² |
| Moment of inertia | mm⁴ | in⁴ |
| Force (axial, shear) | N | lb |
| Moment, torsion | N·mm | lb-in |
| Stress, strength | N/mm² | psi |
| Modulus of elasticity, shear modulus of elasticity | N/mm² | psi |
| Section/Table | SI | FPS Equivalent |
| ------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 6.2.3 | $\beta_1 = 0.85 - 0.008(f_c' - 30)$ | $\beta_1 = 0.85 - 5\times10^{-5}(f_c' - 4000)$ |
| 6.2.5 | $\rho_b = \dfrac{0.85\beta_1f_c'}{f_y}\dfrac{600}{600+f_y}$ | $\rho_b = \dfrac{0.85\beta_1f_c'}{f_y}\dfrac{87000}{87000+f_y}$ |
| | $V_c = 0.17\sqrt{f_c'}b_wd$ | $V_c = 2\sqrt{f_c'}b_wd$ |
| 6.2.7 | $V_c = 0.17\left(1+0.073\dfrac{N_u}{A_g}\right)\sqrt{f_c'}b_wd$ | $V_c = 2\left(1+\dfrac{N_u}{2000A_g}\right)\sqrt{f_c'}b_wd$ |
| | $V_c = \left(0.16\sqrt{f_c'}+17.2\rho_w\dfrac{V_ud}{M_u}\right)b_wd$ | $V_c = \left(1.9\sqrt{f_c'}+2500\rho_w\dfrac{V_ud}{M_u}\right)b_wd$ |
| | $0.3\sqrt{f_c'}b_wd$ | $3.5\sqrt{f_c'}b_wd$ |
| | $V_c = 0.3\sqrt{f_c'}b_wd\sqrt{1+0.3\dfrac{N_u}{A_g}}$ | $V_c = 3.5\sqrt{f_c'}b_wd\sqrt{1+\dfrac{N_u}{500A_g}}$ |
| | $V_c = 0.17\left(1+0.3\dfrac{N_u}{A_g}\right)\sqrt{f_c'}b_wd$ | $V_c = 2\left(1+\dfrac{N_u}{500A_g}\right)\sqrt{f_c'}b_wd$ |
| | $0.33\sqrt{f_c'}b_wd$ | $4\sqrt{f_c'}b_wd$ |
| | $\phi\left[(0.04\sqrt{f_c'})\sum x^2y\right]$ | $\phi\left[(0.5\sqrt{f_c'})\sum x^2y\right]$ |
| | $A_v = 0.35\dfrac{b_ws}{f_y}$ | $A_v = 50\dfrac{b_ws}{f_y}$ |
| | $A_v + 2A_t = 0.35\dfrac{b_ws}{f_y}$ | $A_v + 2A_t = 50\dfrac{b_ws}{f_y}$ |
| | $0.25\sqrt{f_c'}b_wd$ | $3\sqrt{f_c'}b_wd$ |
| | $0.67\sqrt{f_c'}b_wd$ | $8\sqrt{f_c'}b_wd$ |
| | $0.04\sqrt{f_c'}$ | $0.5\sqrt{f_c'}$ |
| | $V_c = \dfrac{0.17\sqrt{f_c'}b_wd}{\sqrt{1+\left(2.5C_t\dfrac{T_u}{V_u}\right)^2}}$ | $V_c = \dfrac{2\sqrt{f_c'}b_wd}{\sqrt{1+\left(2.5C_t\dfrac{T_u}{V_u}\right)^2}}$ |
| | $\phi\left[(0.11\sqrt{f_c'})\sum x^2y\right]$ | $\phi\left[(1.33\sqrt{f_c'})\sum x^2y\right]$ |
| | $T_c = \dfrac{(0.066\sqrt{f_c'})\sum x^2y}{\sqrt{1+\left(\dfrac{0.4V_u}{C_tT_u}\right)^2}}$ | $T_c = \dfrac{(0.8\sqrt{f_c'})\sum x^2y}{\sqrt{1+\left(\dfrac{0.4V_u}{C_tT_u}\right)^2}}$ |
| | $(1+0.3N_u/A_g)$ | $(1+0.002N_u/A_g)$ |
| | $A_\ell = \left[\dfrac{2.8xs}{f_y}\left(\dfrac{T_u}{T_u+\dfrac{V_u}{3C_t}}\right)-2A_t\right]\left(\dfrac{x_1+y_1}{s}\right)$ | $A_\ell = \left[\dfrac{400xs}{f_y}\left(\dfrac{T_u}{T_u+\dfrac{V_u}{3C_t}}\right)-2A_t\right]\left(\dfrac{x_1+y_1}{s}\right)$ |
| | $(0.35b_ws/f_y)$ | $(50b_ws/f_y)$ |
| 6.2.8 | $\rho_{min} = \dfrac{1.38}{f_y}$ | $\rho_{min} = \dfrac{200}{f_y}$ |
| | $(0.4+f_y/685)$ | $(0.4+f_y/100000)$ |
| 6.2.10 | $f_r = 0.62\sqrt{f_c'}$ | $f_r = 7.5\sqrt{f_c'}$ |
| 6.3.8 | $(15+0.03h)$ | $(0.6+0.03h)$ |
| 6.4.3 | $h = \dfrac{\ell_n(0.8+f_y/1400)}{36+5\beta[\alpha_m-0.12(1+1/\beta)]}$ | $h = \dfrac{\ell_n(0.8+f_y/200000)}{36+5\beta[\alpha_m-0.12(1+1/\beta)]}$ |
| | $h = \dfrac{\ell_n(0.8+f_y/1400)}{36+9\beta}$ | $h = \dfrac{\ell_n(0.8+f_y/200000)}{36+9\beta}$ |
| | $h = \dfrac{\ell_n(0.8+f_y/1400)}{36}$ | $h = \dfrac{\ell_n(0.8+f_y/200000)}{36}$ |
| 6.4.7 | $V_c = 0.17(1+2/\beta_c)\sqrt{f_c'}b_od$ | $V_c = 2(1+2/\beta_c)\sqrt{f_c'}b_od$ |
| | $V_c = 0.17\left(1+\dfrac{\alpha_sd}{b_o}\right)\sqrt{f_c'}b_od$ | $V_c = 2\left(1+\dfrac{\alpha_sd}{b_o}\right)\sqrt{f_c'}b_od$ |
| | $0.33\sqrt{f_c'}b_od$ | $4\sqrt{f_c'}b_od$ |
| | $0.5\sqrt{f_c'}b_od$ | $6\sqrt{f_c'}b_od$ |
| | $0.17\sqrt{f_c'}b_od$ | $2\sqrt{f_c'}b_od$ |
| | $0.58\sqrt{f_c'}b_od$ | $7\sqrt{f_c'}b_od$ |
| | $0.33\phi\sqrt{f_c'}$ | $4\phi\sqrt{f_c'}$ |
| 6.8.4 | $V_n \leq 0.67\sqrt{f_c'}b_wd$ | $V_n \leq 8\sqrt{f_c'}b_wd$ |
| | $V_n = 0.056\left(10+\dfrac{\ell_n}{d}\right)\sqrt{f_c'}b_wd$ | $V_n = \dfrac{2}{3}\left(10+\dfrac{\ell_n}{d}\right)\sqrt{f_c'}b_wd$ |
| | $V_c = 0.17\sqrt{f_c'}b_wd$ | $V_c = 2\sqrt{f_c'}b_wd$ |
| | $V_c = \left(3.5-2.5\dfrac{M_u}{V_ud}\right)\left(0.16\sqrt{f_c'}+17.2\rho_w\dfrac{V_ud}{M_u}\right)b_wd$ | $V_c = \left(3.5-2.5\dfrac{M_u}{V_ud}\right)\left(1.9\sqrt{f_c'}+2500\rho_w\dfrac{V_ud}{M_u}\right)b_wd$ |
| | $0.5\sqrt{f_c'}b_wd$ | $6\sqrt{f_c'}b_wd$ |
| 6.9.6 | $0.83\sqrt{f_c'}hd$ | $10\sqrt{f_c'}hd$ |
| | $0.17\sqrt{f_c'}hd$ | $2\sqrt{f_c'}hd$ |
| | $V_c = 0.27\sqrt{f_c'}hd+\dfrac{N_ud}{4\ell_w}$ | $V_c = 3.3\sqrt{f_c'}hd+\dfrac{N_ud}{4\ell_w}$ |
| | $V_c = \left(0.05\sqrt{f_c'}+\dfrac{\ell_w\left(0.1\sqrt{f_c'}+0.2\dfrac{N_u}{\ell_wh}\right)}{\left(\dfrac{M_u}{V_u}-\dfrac{\ell_w}{2}\right)}\right)hd$ | $V_c = \left(0.6\sqrt{f_c'}+\dfrac{\ell_w\left(1.25\sqrt{f_c'}+0.2\dfrac{N_u}{\ell_wh}\right)}{\left(\dfrac{M_u}{V_u}-\dfrac{\ell_w}{2}\right)}\right)hd$ |
| 6.10.4 | $V_c = 0.17\sqrt{f_c'}bd$ | $V_c = 2\sqrt{f_c'}bd$ |
| | $V_c = \left(0.16\sqrt{f_c'}+17.2\rho_w\dfrac{V_ud}{M_u}\right)bd$ | $V_c = \left(1.9\sqrt{f_c'}+2500\rho_w\dfrac{V_ud}{M_u}\right)bd$ |
| | $0.17\sqrt{f_c'}b_od$ | $2\sqrt{f_c'}b_od$ |
| | $0.5\sqrt{f_c'}b_od$ | $6\sqrt{f_c'}b_od$ |
| 6.10.9 | $V_c = 0.8\sqrt{f_c'}bd(2d/a_v)$ | $V_c = 9.6\sqrt{f_c'}bd(2d/a_v)$ |
| | $0.8\phi\sqrt{f_c'}$ | $9.6\phi\sqrt{f_c'}$ |
| 6.12.6 | $0.33\phi\sqrt{f_c'}$ | $4\phi\sqrt{f_c'}$ |
### Chapter 7
The following units are applicable to the corresponding variables in the expressions provided below.
| Quantity | SI Unit | FPS Unit |
| -------------------------------------------------- | ------- | -------- |
| Length, other dimensions | mm | in |
| Area | mm² | in² |
| Moment of inertia | mm⁴ | in⁴ |
| Force (axial, shear) | N | lb |
| Moment, torsion | N·mm | lb-in |
| Stress, strength | N/mm² | psi |
| Modulus of elasticity, shear modulus of elasticity | N/mm² | psi |
| Section/Table | SI | FPS Equivalent |
| ------------- | ------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------- |
| 7.1.9 | $0.091\sqrt{f_c'}$ | $1.1\sqrt{f_c'}$ |
| | $0.457\sqrt{f_c'}$ | $5.5\sqrt{f_c'}$ |
| | $0.10\sqrt{f_c'}$ | $1.2\sqrt{f_c'}$ |
| | $(0.083+0.17/\beta_c)\sqrt{f_c'} \leq 0.17\sqrt{f_c'}$ | $(1+2/\beta_c)\sqrt{f_c'} \leq 2\sqrt{f_c'}$ |
| | $0.3\sqrt{f_c'}$ | $3.6\sqrt{f_c'}$ |
| 7.2.7 | $0.091\sqrt{f_c'}b_wd$ | $1.1\sqrt{f_c'}b_wd$ |
| | $V_c = 0.091\left(1+0.58\dfrac{N}{A_g}\right)\sqrt{f_c'}b_wd$ | $V_c = 1.1\left(1+\dfrac{N}{250A_g}\right)\sqrt{f_c'}b_wd$ |
| | $V_c = \left(0.083\sqrt{f_c'}+9\rho_w\dfrac{Vd}{M}\right)b_wd \leq 0.16\sqrt{f_c'}b_wd$ | $V_c = \left(\sqrt{f_c'}+1300\rho_w\dfrac{Vd}{M}\right)b_wd \leq 1.9\sqrt{f_c'}b_wd$ |
| | $V_c = 0.091\left(1+0.09\dfrac{N}{A_g}\right)\sqrt{f_c'}b_wd$ | $V_c = 1.1\left(1+\dfrac{N}{1667A_g}\right)\sqrt{f_c'}b_wd$ |
| | $0.023\sqrt{f_c'}\sum x^2y$ | $0.275\sqrt{f_c'}\sum x^2y$ |
| | $V_c = \dfrac{0.091\sqrt{f_c'}b_wd}{\sqrt{1+(2.5C_tT/V)^2}}$ | $V_c = \dfrac{1.1\sqrt{f_c'}b_wd}{\sqrt{1+(2.5C_tT/V)^2}}$ |
| | $0.17\sqrt{f_c'}b_wd$ | $2\sqrt{f_c'}b_wd$ |
| | $A_v = 0.35\dfrac{b_ws}{f_y}$ | $A_v = 50\dfrac{b_ws}{f_y}$ |
| | $0.133\sqrt{f_c'}b_wd$ | $1.6\sqrt{f_c'}b_wd$ |
| | $0.365\sqrt{f_c'}b_wd$ | $4.4\sqrt{f_c'}b_wd$ |
| | $(0.06\sqrt{f_c'})\sum x^2y$ | $(0.72\sqrt{f_c'})\sum x^2y$ |
| | $T_c = \dfrac{(0.036\sqrt{f_c'})\sum x^2y}{\sqrt{1+\left(\dfrac{0.4V}{C_tT}\right)^2}}$ | $T_c = \dfrac{(0.44\sqrt{f_c'})\sum x^2y}{\sqrt{1+\left(\dfrac{0.4V}{C_tT}\right)^2}}$ |
| | $(1+0.3N/A_g)$ | $(1+0.002N/A_g)$ |
| | $A_\ell = \left[\dfrac{2.8xs}{f_y}\left(\dfrac{T}{T+\dfrac{V}{3C_t}}\right)-2A_t\right]\left(\dfrac{x_1+y_1}{s}\right)$ | $A_\ell = \left[\dfrac{400xs}{f_y}\left(\dfrac{T}{T+\dfrac{V}{3C_t}}\right)-2A_t\right]\left(\dfrac{x_1+y_1}{s}\right)$ |
| | $A_\ell = \left[\dfrac{2.8xs}{f_y}\left(\dfrac{T}{T+\dfrac{V}{3C_t}}\right)-\dfrac{b_ws}{3f_y}\right]\left(\dfrac{x_1+y_1}{s}\right)$ | $A_\ell = \left[\dfrac{400xs}{f_y}\left(\dfrac{T}{T+\dfrac{V}{3C_t}}\right)-\dfrac{50b_ws}{f_y}\right]\left(\dfrac{x_1+y_1}{s}\right)$ |
| 7.2.8 | $\rho_{min} = \dfrac{1.38}{f_y}$ | $\rho_{min} = \dfrac{200}{f_y}$ |
| 7.4.4 | $v_c = 0.083\left(1+\dfrac{2}{\beta_c}\right)\sqrt{f_c'} \leq 0.17\sqrt{f_c'}$ | $v_c = \left(1+\dfrac{2}{\beta_c}\right)\sqrt{f_c'} \leq 2\sqrt{f_c'}$ |
| 7.4.5 | $0.083\sqrt{f_c'}$ | $\sqrt{f_c'}$ |
| | $0.25\sqrt{f_c'}$ | $3\sqrt{f_c'}$ |
| 7.4.6 | $0.29\sqrt{f_c'}$ | $3.5\sqrt{f_c'}$ |
| | $0.17\sqrt{f_c'}$ | $2\sqrt{f_c'}$ |
| 7.8.4 | $0.37\sqrt{f_c'}b_wd$ | $4.5\sqrt{f_c'}b_wd$ |
| | $V_n = 0.031\left(10+\dfrac{\ell_n}{d}\right)\sqrt{f_c'}b_wd$ | $V_n = 0.37\left(10+\dfrac{\ell_n}{d}\right)\sqrt{f_c'}b_wd$ |
| | $V_c = 0.091\sqrt{f_c'}b_wd$ | $V_c = 1.1\sqrt{f_c'}b_wd$ |
| | $V_c = \left(1.93-1.38\dfrac{M}{Vd}\right)\left(0.16\sqrt{f_c'}+17.2\rho_w\dfrac{Vd}{M}\right)b_wd$ | $V_c = \left(1.93-1.38\dfrac{M}{Vd}\right)\left(1.9\sqrt{f_c'}+2500\rho_w\dfrac{Vd}{M}\right)b_wd$ |
| | $0.275\sqrt{f_c'}b_wd$ | $3.3\sqrt{f_c'}b_wd$ |
| 7.10.8 | $v_c = \left(0.083+\dfrac{0.17}{\beta_c}\right)\sqrt{f_c'} \leq 0.17\sqrt{f_c'}$ | $v_c = \left(1+\dfrac{2}{\beta_c}\right)\sqrt{f_c'} \leq 2\sqrt{f_c'}$ |
| | $0.083\sqrt{f_c'}$ | $\sqrt{f_c'}$ |
| | $0.25\sqrt{f_c'}$ | $3\sqrt{f_c'}$ |
| | $V_c = 0.4\sqrt{f_c'}bd(2d/a_v)$ | $V_c = 4.8\sqrt{f_c'}bd(2d/a_v)$ |
| | $0.4\sqrt{f_c'}$ | $4.8\sqrt{f_c'}$ |
| 7.12 | $0.17\sqrt{f_c'}$ | $2\sqrt{f_c'}$ |
### Chapter 8
The following units are applicable to the corresponding variables in the expressions provided below.
| Quantity | SI Unit | FPS Unit |
| ------------------------ | ------- | -------- |
| Length, other dimensions | mm | in |
| Area | mm² | in² |
| Force (axial, shear) | N | lb |
| Stress, strength | N/mm² | psi |
| Section/Table | SI | FPS Equivalent |
| ------------- | ---------------------------------------------------- | ------------------------------------------------- |
| 8.2.3 | $0.02A_bf_y/\sqrt{f_c'}$ | $0.04A_bf_y/\sqrt{f_c'}$ |
| | $25f_y/\sqrt{f_c'}$ | $0.085f_y/\sqrt{f_c'}$ |
| | $35f_y/\sqrt{f_c'}$ | $0.125f_y/\sqrt{f_c'}$ |
| | $0.375d_bf_y/\sqrt{f_c'}$ | $0.03d_bf_y/\sqrt{f_c'}$ |
| 8.2.4 | $0.24d_bf_y/\sqrt{f_c'}$ | $0.02d_bf_y/\sqrt{f_c'}$ |
| | $0.04d_bf_y$ | $0.0003d_bf_y$ |
| 8.2.6 | $100d_b/\sqrt{f_c'}$ | $1200d_b/\sqrt{f_c'}$ |
| | $f_y/410$ | $f_y/60000$ |
| 8.2.7 | $0.4b_ws/f_y$ | $60b_ws/f_y$ |
| 8.2.10 | $0.175d_bf_y/\sqrt{f_c'}$ | $0.014d_bf_y/\sqrt{f_c'}$ |
| 8.2.14 | $0.07f_yd_b$ | $0.0005f_yd_b$ |
| | $(0.13f_y-24)d_b$ | $(0.0009f_y-24)d_b$ |
| 8.3.4 | $1.38b_wd/f_y$ | $200b_wd/f_y$ |
| 8.3.6 | $0.083A_{cv}\sqrt{f_c'}$ | $A_{cv}\sqrt{f_c'}$ |
| | $0.17A_{cv}\sqrt{f_c'}$ | $2A_{cv}\sqrt{f_c'}$ |
| 8.3.7 | $1.66\sqrt{f_c'}A_j$ | $20\sqrt{f_c'}A_j$ |
| | $1.24\sqrt{f_c'}A_j$ | $15\sqrt{f_c'}A_j$ |
| | $1.0\sqrt{f_c'}A_j$ | $12\sqrt{f_c'}A_j$ |
| | $\ell_{dh} = 0.185f_yd_b/\sqrt{f_c'}$ | $\ell_{dh} = 0.0154f_yd_b/\sqrt{f_c'}$ |
| 8.3.8 | $V_n = A_{cv}\left(0.17\sqrt{f_c'}+\rho_nf_y\right)$ | $V_n = A_{cv}\left(2\sqrt{f_c'}+\rho_nf_y\right)$ |
| | $\alpha_c$ varies linearly from 0.25 to 0.17 | $\alpha_c$ varies linearly from 3.0 to 2.0 |
| | $0.67A_{cv}\sqrt{f_c'}$ | $8A_{cv}\sqrt{f_c'}$ |
| | $0.83A_{cp}\sqrt{f_c'}$ | $10A_{cp}\sqrt{f_c'}$ |
### Chapter 9
The following units are applicable to the corresponding variables in the expressions provided below.
| Quantity | SI Unit | FPS Unit |
| ------------------------ | ------- | -------- |
| Length, other dimensions | mm | in |
| Area | mm² | in² |
| Moment of inertia | mm⁴ | in⁴ |
| Force (axial, shear) | N | lb |
| Moment, torsion | N·mm | lb-in |
| Stress, strength | N/mm² | psi |
| Section/Table | SI | FPS Equivalent |
| ------------- | ------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------- |
| 9.5.5 | $\beta_1 = 0.85 - 0.008(f_c' - 30)$ | $\beta_1 = 0.85 - 5\times10^{-5}(f_c' - 4000)$ |
| 9.8.1 | $f_t = 0.50\sqrt{f_c'}$ | $f_t = 6\sqrt{f_c'}$ |
| | $f_t = 0.40\sqrt{f_c'}$ | $f_t = 4.8\sqrt{f_c'}$ |
| | $f_t = 0.70F\sqrt{f_c'}$ | $f_t = 8.4F\sqrt{f_c'}$ |
| | $f_t = 0.85F\sqrt{f_c'}$ | $f_t = 10.2F\sqrt{f_c'}$ |
| | $f_t = 0.90F\sqrt{f_c'}$ | $f_t = 10.8F\sqrt{f_c'}$ |
| | $f_t = 1.00F\sqrt{f_c'}$ | $f_t = 12.0F\sqrt{f_c'}$ |
| | $F = 1.2 - \dfrac{d}{2000}$ | $F = 1.2 - \dfrac{d}{80}$ |
| | $0.50\sqrt{f_{ci}'}$ | $6\sqrt{f_{ci}'}$ |
| | $0.40\sqrt{f_{ci}'}$ | $4.8\sqrt{f_{ci}'}$ |
| 9.13.1 | $\dfrac{A_{ps}f_{ps}+A_sf_y-A_s'f_y}{bd} \geq 0.85\beta_1f_c'\dfrac{d'}{d}\left(\dfrac{600}{600-f_y}\right)$ | $\dfrac{A_{ps}f_{ps}+A_sf_y-A_s'f_y}{bd} \geq 0.85\beta_1f_c'\dfrac{d'}{d}\left(\dfrac{87000}{87000-f_y}\right)$ |
| 9.13.2 | $f_{ps} = f_{se}+69+\dfrac{f_c'}{100\rho_p}$ | $f_{ps} = f_{se}+10{,}000+\dfrac{f_c'}{100\rho_p}$ |
| | $(f_{se}+414)$ | $(f_{se}+60{,}000)$ |
| | $f_{ps} = f_{se}+69+\dfrac{f_c'}{300\rho_p}$ | $f_{ps} = f_{se}+10{,}000+\dfrac{f_c'}{300\rho_p}$ |
| | $(f_{se}+207)$ | $(f_{se}+30{,}000)$ |
| 9.14.3 | $f_r = 0.62\sqrt{f_c'}$ | $f_r = 7.5\sqrt{f_c'}$ |
| 9.15.3 | $0.17\sqrt{f_c'}$ | $2\sqrt{f_c'}$ |
| 9.16 | $\ell_t = \dfrac{K_td_b}{\sqrt{f_{ci}'}}$ | $\ell_t = \dfrac{12K_td_b}{\sqrt{f_{ci}'}}$ |
| 9.19.2 | $V_c = \left(0.05\sqrt{f_c'}+4.8\dfrac{V_ud}{M_u}\right)b_wd$ | $V_c = \left(0.6\sqrt{f_c'}+700\dfrac{V_ud}{M_u}\right)b_wd$ |
| | $0.17\sqrt{f_c'}b_wd$ | $2\sqrt{f_c'}b_wd$ |
| | $0.42\sqrt{f_c'}b_wd$ | $5\sqrt{f_c'}b_wd$ |
| | $V_{ci} = 0.05\sqrt{f_c'}b_wd+V_d+\dfrac{V_iM_{cr}}{M_{max}}$ | $V_{ci} = 0.6\sqrt{f_c'}b_wd+V_d+\dfrac{V_iM_{cr}}{M_{max}}$ |
| | $0.14\sqrt{f_c'}b_wd$ | $1.7\sqrt{f_c'}b_wd$ |
| | $M_{cr} = (I/y_t)\left(0.5\sqrt{f_c'}+f_{pe}-f_d\right)$ | $M_{cr} = (I/y_t)\left(6\sqrt{f_c'}+f_{pe}-f_d\right)$ |
| | $V_{cw} = \left(0.29\sqrt{f_c'}+0.3f_{pc}\right)b_wd+V_p$ | $V_{cw} = \left(3.5\sqrt{f_c'}+0.3f_{pc}\right)b_wd+V_p$ |
| 9.19.3 | $0.33\sqrt{f_c'}b_wd$ | $4\sqrt{f_c'}b_wd$ |
| | $\phi\left(0.04\sqrt{f_c'}\sum x^2y\right)$ | $\phi\left(0.5\sqrt{f_c'}\sum x^2y\right)$ |
| | $A_v = 0.35\dfrac{b_ws}{f_y}$ | $A_v = 50\dfrac{b_ws}{f_y}$ |
| | $A_v+2A_t = 0.35\dfrac{b_ws}{f_y}$ | $A_v+2A_t = 50\dfrac{b_ws}{f_y}$ |
| | $0.67\sqrt{f_c'}b_wd$ | $8\sqrt{f_c'}b_wd$ |
### Chapter 10
The following units are applicable to the corresponding variables in the expressions provided below.
| Quantity | SI Unit | FPS Unit |
| -------------------------------------------------- | ------- | -------- |
| Length, other dimensions | mm | in |
| Area | mm² | in² |
| Section modulus | mm³ | in³ |
| Moment of inertia, torsional constant | mm⁴ | in⁴ |
| Force, load, strength | kN | kips |
| Moment, torsion | kN·m | kip-in |
| Stress | N/mm² | ksi |
| Modulus of elasticity, shear modulus of elasticity | N/mm² | ksi |
| Warping constant | mm⁶ | in⁶ |
Chapter 10 (Steel Structures) is by far the densest section of Appendix A, with well over a hundred paired expressions. Each row below reproduces one SI expression from the Code and its FPS equivalent, in the same order as the source table, grouped by the Section/Table reference given in the source (a blank Section/Table cell means the expression continues under the row above it).
| Section/Table | SI | FPS Equivalent |
| ------------- | ------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------- |
| Table 6.10.1 | $170/\sqrt{F_y}$ | $65/\sqrt{F_y}$ |
| | $250/\sqrt{F_y}$ | $95/\sqrt{F_y}$ |
| | $250/\sqrt{F_{yf}/k_c}$ | $95/\sqrt{F_{yf}/k_c}$ |
| | $250/\sqrt{F_y/k_c}$ | $95/\sqrt{F_y/k_c}$ |
| | $333/\sqrt{F_y}$ | $127/\sqrt{F_y}$ |
| | $200/\sqrt{F_y}$ | $76/\sqrt{F_y}$ |
| | $500/\sqrt{F_y}$ | $190/\sqrt{F_y}$ |
| | $625/\sqrt{F_y}$ | $238/\sqrt{F_y}$ |
| | $832/\sqrt{F_y}$ | $317/\sqrt{F_y}$ |
| | $665/\sqrt{F_y}$ | $253/\sqrt{F_y}$ |
| | $1680/\sqrt{F_y}$ | $640/\sqrt{F_y}$ |
| | $1995/\sqrt{F_b}$ | $760/\sqrt{F_b}$ |
| | $\dfrac{1680}{\sqrt{F_y}}\left(1-3.74\dfrac{f_a}{F_y}\right)$ | $\dfrac{640}{\sqrt{F_y}}\left(1-3.74\dfrac{f_a}{F_y}\right)$ |
| | $675/\sqrt{F_y}$ | $257/\sqrt{F_y}$ |
| | $1995/\sqrt{F_b}$ | $760/\sqrt{F_b}$ |
| | $22752/F_y$ | $3300/F_y$ |
| 10.7.5 | $200/\sqrt{F_y} < b/t < 407/\sqrt{F_y}$ | $76/\sqrt{F_y} < b/t < 155/\sqrt{F_y}$ |
| | $Q_s = 1.340 - 0.0017(b/t)\sqrt{F_y}$ | $Q_s = 1.340 - 0.00447(b/t)\sqrt{F_y}$ |
| | $Q_s = 106867/\left[F_y(b/t)^2\right]$ | $Q_s = 15500/\left[F_y(b/t)^2\right]$ |
| | $250/\sqrt{F_y/k_c} < b/t < 512/\sqrt{F_y/k_c}$ | $95/\sqrt{F_y/k_c} < b/t < 195/\sqrt{F_y/k_c}$ |
| | $Q_s = 1.293 - 0.0012(b/t)\sqrt{F_y/k_c}$ | $Q_s = 1.293 - 0.00309(b/t)\sqrt{F_y/k_c}$ |
| | $Q_s = 180640k_c/\left[F_y(b/t)^2\right]$ | $Q_s = 26200k_c/\left[F_y(b/t)^2\right]$ |
| | $333/\sqrt{F_y} < b/t < 462/\sqrt{F_y}$ | $127/\sqrt{F_y} < b/t < 176/\sqrt{F_y}$ |
| | $Q_s = 1.908 - 0.0027(b/t)\sqrt{F_y}$ | $Q_s = 1.908 - 0.00715(b/t)\sqrt{F_y}$ |
| | $Q_s = 137890/\left[F_y(b/t)^2\right]$ | $Q_s = 20000/\left[F_y(b/t)^2\right]$ |
| | $b_e = \dfrac{665t}{\sqrt{f}}\left[1-\dfrac{132}{(b/t)\sqrt{f}}\right] \leq b$ | $b_e = \dfrac{253t}{\sqrt{f}}\left[1-\dfrac{50.3}{(b/t)\sqrt{f}}\right] \leq b$ |
| | $b_e = \dfrac{665t}{\sqrt{f}}\left[1-\dfrac{116}{(b/t)\sqrt{f}}\right] \leq b$ | $b_e = \dfrac{253t}{\sqrt{f}}\left[1-\dfrac{44.3}{(b/t)\sqrt{f}}\right] \leq b$ |
| | $F_a = \dfrac{4564}{D/t}+0.40F_y$ | $F_a = \dfrac{662}{D/t}+0.40F_y$ |
| 10.7.6 | $\dfrac{200b_f}{\sqrt{F_y}}$ or $\dfrac{138000}{(d/A_f)F_y}$ | $\dfrac{76b_f}{\sqrt{F_y}}$ or $\dfrac{20000}{(d/A_f)F_y}$ |
| | $F_b = F_y\left[0.79-0.00038\dfrac{b_f}{t_f}\sqrt{F_y}\right]$ | $F_b = F_y\left[0.79-0.001\dfrac{b_f}{t_f}\sqrt{F_y}\right]$ |
| | $F_b = F_y\left[0.79-0.00038\dfrac{b_f}{t_f}\sqrt{F_y/k_c}\right]$ | $F_b = F_y\left[0.79-0.001\dfrac{b_f}{t_f}\sqrt{F_y/k_c}\right]$ |
| | $\dfrac{200b_f}{\sqrt{F_y}}$ | $\dfrac{76b_f}{\sqrt{F_y}}$ |
| | $\sqrt{\dfrac{703\times10^3C_b}{F_y}} \leq \dfrac{l}{r_T} \leq \sqrt{\dfrac{3516\times10^3C_b}{F_y}}$ | $\sqrt{\dfrac{102\times10^3C_b}{F_y}} \leq \dfrac{l}{r_T} \leq \sqrt{\dfrac{510\times10^3C_b}{F_y}}$ |
| | $F_b = \left[\dfrac{2}{3}-\dfrac{F_y(l/r_T)^2}{10550\times10^3C_b}\right]F_y \leq 0.60F_y$ | $F_b = \left[\dfrac{2}{3}-\dfrac{F_y(l/r_T)^2}{1530\times10^3C_b}\right]F_y \leq 0.60F_y$ |
| | $F_b = \dfrac{1172\times10^3C_b}{(l/r_T)^2} \leq 0.60F_y$ | $F_b = \dfrac{170\times10^3C_b}{(l/r_T)^2} \leq 0.60F_y$ |
| | $F_b = \dfrac{83\times10^3C_b}{(ld/A_f)} \leq 0.60F_y$ | $F_b = \dfrac{12\times10^3C_b}{(ld/A_f)} \leq 0.60F_y$ |
| | $F_b = F_y\left[1.075-0.00095\left(\dfrac{b_f}{t_f}\right)\sqrt{F_y}\right]$ | $F_b = F_y\left[1.075-0.0025\left(\dfrac{b_f}{t_f}\right)\sqrt{F_y}\right]$ |
| | $L_c = \left(13445+8274\dfrac{M_1}{M_2}\right)\dfrac{b}{F_y}$ | $L_c = \left(1950+1200\dfrac{M_1}{M_2}\right)\dfrac{b}{F_y}$ |
| | $1000/\sqrt{F_y}$ | $380/\sqrt{F_y}$ |
| | $C_v = \dfrac{310260k_v}{F_y(h/t_w)^2} = \dfrac{500}{h/t_w}\sqrt{\dfrac{k_v}{F_y}}$ | $C_v = \dfrac{45000k_v}{F_y(h/t_w)^2} = \dfrac{190}{h/t_w}\sqrt{\dfrac{k_v}{F_y}}$ |
| | $F_{s\gamma} = \dfrac{2.1\times10^6}{h_sLd_o/A_f}$ | $F_{s\gamma} = \dfrac{12\times10^3}{h_sLd_o/A_f}$ |
| | $F_{w\gamma} = \dfrac{756\times10^6}{(h_wL/r_{T_o})^2}$ | $F_{w\gamma} = \dfrac{170\times10^6}{(h_wL/r_{T_o})^2}$ |
| 10.7.7 | $1995/\sqrt{F_b}$ | $760/\sqrt{F_b}$ |
| | $\dfrac{h}{t_w} \leq \dfrac{96550}{\sqrt{F_{yf}(F_{yf}+114)}}$ | $\dfrac{h}{t_w} \leq \dfrac{14000}{\sqrt{F_{yf}(F_{yf}+16.5)}}$ |
| | $\dfrac{h}{t_w} \leq \dfrac{5250}{\sqrt{F_{yf}}}$ | $\dfrac{h}{t_w} \leq \dfrac{2000}{\sqrt{F_{yf}}}$ |
| | $R_{PG} = 1-0.0005\dfrac{A_w}{A_f}\left(\dfrac{h}{t}-\dfrac{1995}{\sqrt{F_b}}\right) \leq 1.0$ | $R_{PG} = 1-0.0005\dfrac{A_w}{A_f}\left(\dfrac{h}{t}-\dfrac{760}{\sqrt{F_b}}\right) \leq 1.0$ |
| | $f_{vs} = h\sqrt{\left(\dfrac{F_y}{647}\right)^3}$ | $f_{vs} = h\sqrt{\left(\dfrac{F_y}{340}\right)^3}$ |
| 10.7.11 | $t_f < 12.65\sqrt{P_{bf}/F_{yc}}$ | $t_f < 0.4\sqrt{P_{bf}/F_{yc}}$ |
| | $\dfrac{1000R}{t_w(N+5k)} \leq 0.66F_y$ | $\dfrac{R}{t_w(N+5k)} \leq 0.66F_y$ |
| | $\dfrac{1000R}{t_w(N+2.5k)} \leq 0.66F_y$ | $\dfrac{R}{t_w(N+5k)} \leq 0.66F_y$ |
| | $R = 0.177t_w^2\left[1+3\left(\dfrac{N}{d}\right)\left(\dfrac{t_w}{t_f}\right)^{1.5}\right]\sqrt{F_{yw}t_f/t_w}$ | $R = 67.5t_w^2\left[1+3\left(\dfrac{N}{d}\right)\left(\dfrac{t_w}{t_f}\right)^{1.5}\right]\sqrt{F_{yw}t_f/t_w}$ |
| | $R = 0.089t_w^2\left[1+3\left(\dfrac{N}{d}\right)\left(\dfrac{t_w}{t_f}\right)^{1.5}\right]\sqrt{F_{yw}t_f/t_w}$ | $R = 34t_w^2\left[1+3\left(\dfrac{N}{d}\right)\left(\dfrac{t_w}{t_f}\right)^{1.5}\right]\sqrt{F_{yw}t_f/t_w}$ |
| | $R = \dfrac{46.88t_w^3}{h}\left[1+0.4\left(\dfrac{d_c/t_w}{l/b_f}\right)^3\right]$ | $R = \dfrac{6800t_w^3}{h}\left[1+0.4\left(\dfrac{d_c/t_w}{l/b_f}\right)^3\right]$ |
| | $R = \dfrac{46.88t_w^3}{h}\left[0.4\left(\dfrac{d_c/t_w}{l/b_f}\right)^3\right]$ | $R = \dfrac{6800t_w^3}{h}\left[0.4\left(\dfrac{d_c/t_w}{l/b_f}\right)^3\right]$ |
| | $\dfrac{10.76t_{wc}^3\sqrt{F_{yc}}}{P_{bf}}$ | $\dfrac{4100t_{wc}^3\sqrt{F_{yc}}}{P_{bf}}$ |
| | $\dfrac{1000P_{bf}-F_{yc}t_{wc}(t_b+5k)}{F_{yst}}$ | $\dfrac{P_{bf}-F_{yc}t_{wc}(t_b+5k)}{F_{yst}}$ |
| | $I_d \geq 3955S^4$ | $I_d \geq 25\times10^{-6}S^4$ |
| | $C_p = \dfrac{506L_sL_p^4}{I_p}$ | $C_p = \dfrac{32L_sL_p^4}{I_p}$ |
| | $C_s = \dfrac{506SL_s^4}{I_s}$ | $C_s = \dfrac{32SL_s^4}{I_s}$ |
| Table 6.10.4 | $170/\sqrt{F_y}$ | $65/\sqrt{F_y}$ |
| | $369/\sqrt{F_y-69}$ | $141/\sqrt{F_y-10}$ |
| | $170/\sqrt{F_{yf}}$ | $65/\sqrt{F_{yf}}$ |
| | $278/\sqrt{F_{yw}-114}$ | $106/\sqrt{F_{yw}-16.5}$ |
| | $250/\sqrt{F_y}$ | $95/\sqrt{F_y}$ |
| | $500/\sqrt{F_y}$ | $190/\sqrt{F_y}$ |
| | $625/\sqrt{F_y-F_r}$ | $238/\sqrt{F_y-F_r}$ |
| | $832/\sqrt{F_y-F_r}$ | $317/\sqrt{F_y-F_r}$ |
| | $200/\sqrt{F_y}$ | $76/\sqrt{F_y}$ |
| | $333/\sqrt{F_y}$ | $127/\sqrt{F_y}$ |
| | $665/\sqrt{F_y}$ | $253/\sqrt{F_y}$ |
| | $1680/\sqrt{F_y}$ | $640/\sqrt{F_y}$ |
| | $2547/\sqrt{F_y}$ | $970/\sqrt{F_y}$ |
| | $\dfrac{1680}{\sqrt{F_y}}\left(1-\dfrac{2.75P_u}{\phi_bP_y}\right)$ | $\dfrac{640}{\sqrt{F_y}}\left(1-\dfrac{2.75P_u}{\phi_bP_y}\right)$ |
| | $\dfrac{502}{\sqrt{F_y}}\left(2.33-\dfrac{P_u}{\phi_bP_y}\right) \geq \dfrac{665}{\sqrt{F_y}}$ | $\dfrac{191}{\sqrt{F_y}}\left(2.33-\dfrac{P_u}{\phi_bP_y}\right) \geq \dfrac{253}{\sqrt{F_y}}$ |
| | $14272/F_y$ | $2070/F_y$ |
| | $22752/F_y$ | $3300/F_y$ |
| | $61845/F_y$ | $8970/F_y$ |
| 10.8.4 | $P_n = 0.001F_yA_g$ | $P_n = F_yA_g$ |
| | $P_n = 0.001F_uA_e$ | $P_n = F_uA_e$ |
| | $P_n = 0.002tb_{eff}F_u$ | $P_n = 2tb_{eff}F_u$ |
| | $P_n = 0.0006A_{sf}F_u$ | $P_n = 0.6A_{sf}F_u$ |
| | $P_n = 0.001A_{pb}F_y$ | $P_n = A_{pb}F_y$ |
| | $b_{eff} = 2t+16$ | $b_{eff} = 2t+0.63$ |
| 10.8.5 | $P_n = 0.001A_gF_{cr}$ | $P_n = A_gF_{cr}$ |
| | $333/\sqrt{F_y}$ | $127/\sqrt{F_y}$ |
| | $500/\sqrt{F_y}$ | $190/\sqrt{F_y}$ |
| | $200/\sqrt{F_y} < b/t < 407/\sqrt{F_y}$ | $76/\sqrt{F_y} < b/t < 155/\sqrt{F_y}$ |
| | $Q_s = 1.340-0.0017(b/t)\sqrt{F_y}$ | $Q_s = 1.340-0.00447(b/t)\sqrt{F_y}$ |
| | $Q_s = 106867/\left[F_y(b/t)^2\right]$ | $Q_s = 15500/\left[F_y(b/t)^2\right]$ |
| | $250/\sqrt{F_y} < b/t < 462/\sqrt{F_y}$ | $95/\sqrt{F_y} < b/t < 176/\sqrt{F_y}$ |
| | $Q_s = 1.415-0.00166(b/t)\sqrt{F_y}$ | $Q_s = 1.415-0.00437(b/t)\sqrt{F_y}$ |
| | $Q_s = 137890/\left[F_y(b/t)^2\right]$ | $Q_s = 20000/\left[F_y(b/t)^2\right]$ |
| | $333/\sqrt{F_y} < b/t < 462/\sqrt{F_y}$ | $127/\sqrt{F_y} < b/t < 176/\sqrt{F_y}$ |
| | $Q_s = 1.908-0.0027(b/t)\sqrt{F_y}$ | $Q_s = 1.908-0.00715(b/t)\sqrt{F_y}$ |
| | $b_e = \dfrac{856t}{\sqrt{f}}\left[1-\dfrac{170}{(b/t)\sqrt{f}}\right] \leq b$ | $b_e = \dfrac{326t}{\sqrt{f}}\left[1-\dfrac{64.9}{(b/t)\sqrt{f}}\right] \leq b$ |
| | $b_e = \dfrac{856t}{\sqrt{f}}\left[1-\dfrac{150}{(b/t)\sqrt{f}}\right] \leq b$ | $b_e = \dfrac{326t}{\sqrt{f}}\left[1-\dfrac{57.2}{(b/t)\sqrt{f}}\right] \leq b$ |
| | $Q = \dfrac{7584}{F_y(D/t)}+\dfrac{2}{3}$ | $Q = \dfrac{1100}{F_y(D/t)}+\dfrac{2}{3}$ |
| 10.8.6 | $L_{pd} = \dfrac{25000+15000(M_1/M_p)}{F_y}r_y$ | $L_{pd} = \dfrac{3600+2200(M_1/M_p)}{F_y}r_y$ |
| | $L_{pd} = \dfrac{34500+20700(M_1/M_p)}{F_y}r_y \geq 20700r_y/F_y$ | $L_{pd} = \dfrac{5000+3000(M_1/M_p)}{F_y}r_y \geq 3000r_y/F_y$ |
| | $L_p = \dfrac{790r_y}{\sqrt{F_{yf}}}$ | $L_p = \dfrac{300r_y}{\sqrt{F_{yf}}}$ |
| | $L_p = \dfrac{25.86\times10^{-3}r_y}{M_p}\sqrt{JA}$ | $L_p = \dfrac{3750r_y}{M_p}\sqrt{JA}$ |
| | $M_r = 10^{-6}(F_{yw}-F_r)S_x$ | $M_r = (F_{yw}-F_r)S_x$ |
| | $L_r = \dfrac{0.393r_y\sqrt{JA}}{M_r}$ | $L_r = \dfrac{57000r_y\sqrt{JA}}{M_r}$ |
| | $M_r = 10^{-6}F_yS_x$ | $M_r = F_yS_x$ |
| | $M_{cr} = 10^{-6}C_b\dfrac{M}{L_b}\sqrt{EI_yGJ+\left(\dfrac{\pi E}{L_b}\right)^2I_yC_w}$ | $M_{cr} = C_b\dfrac{M}{L_b}\sqrt{EI_yGJ+\left(\dfrac{\pi E}{L_b}\right)^2I_yC_w}$ |
| | $= 10^{-6}\dfrac{C_bS_xX_1\sqrt{2}}{L_b/r_y}\sqrt{1+\dfrac{X_1^2X_2}{2(L_b/r_y)^2}}$ | $= \dfrac{C_bS_xX_1\sqrt{2}}{L_b/r_y}\sqrt{1+\dfrac{X_1^2X_2}{2(L_b/r_y)^2}}$ |
| | $M_{cr} = \dfrac{0.393C_b\sqrt{JA}}{L_b/r_y}$ | $M_{cr} = \dfrac{57000C_b\sqrt{JA}}{L_b/r_y}$ |
| | $M_n = M_{cr} = 10^{-6}\dfrac{C_b\pi\sqrt{EI_yGJ}}{L_b}\left[B+\sqrt{1+B^2}\right] \leq M$ | $M_n = M_{cr} = \dfrac{C_b\pi\sqrt{EI_yGJ}}{L_b}\left[B+\sqrt{1+B^2}\right] \leq M$ |
| | $M_n = M_{cr} = 10^{-6}SF_{cr}$ | $M_n = M_{cr} = SF_{cr}$ |
| | $\dfrac{h}{t_w} \leq 490\sqrt{k/F_{yw}}$ | $\dfrac{h}{t_w} \leq 187\sqrt{k/F_{yw}}$ |
| | $V_n = 0.0006F_{yw}A_w$ | $V_n = 0.6F_{yw}A_w$ |
| | $490\sqrt{k/F_{yw}} < \dfrac{h}{t_w} \leq 615\sqrt{k/F_{yw}}$ | $187\sqrt{k/F_{yw}} < \dfrac{h}{t_w} \leq 234\sqrt{k/F_{yw}}$ |
| | $V_n = 0.0006F_{yw}A_w\dfrac{490\sqrt{k/F_{yw}}}{h/t_w}$ | $V_n = 0.6F_{yw}A_w\dfrac{187\sqrt{k/F_{yw}}}{h/t_w}$ |
| | $\dfrac{h}{t_w} > 615\sqrt{k/F_{yw}}$ | $\dfrac{h}{t_w} > 234\sqrt{k/F_{yw}}$ |
| | $V_n = A_w\dfrac{182k}{(h/t_w)^2}$ | $V_n = A_w\dfrac{26400k}{(h/t_w)^2}$ |
| | $\left(\dfrac{h}{t_w}\right)_{max} = \dfrac{5250}{\sqrt{F_{yf}}}$ | $\left(\dfrac{h}{t_w}\right)_{max} = \dfrac{2000}{\sqrt{F_{yf}}}$ |
| | $\left(\dfrac{h}{t_w}\right)_{max} = \dfrac{96525}{\sqrt{F_{yf}(F_{yf}+114)}}$ | $\left(\dfrac{h}{t_w}\right)_{max} = \dfrac{14000}{\sqrt{F_{yf}(F_{yf}+16.5)}}$ |
| | $h/t_w \leq 1100/\sqrt{F_{yw}}$ | $h/t_w \leq 418/\sqrt{F_{yw}}$ |
| | $M_n = 1.67\times10^{-3}S_x'F_{by}$ | $M_n = 1.67S_x'F_{by}$ |
| | $F_{sy} = \dfrac{82735}{(h_sLd_o/A_f)}$ | $F_{sy} = \dfrac{12000}{(h_sLd_o/A_f)}$ |
| | $F_{wy} = \dfrac{1172\times10^3}{(h_wL/r_{T_o})^2}$ | $F_{wy} = \dfrac{170\times10^3}{(h_wL/r_{T_o})^2}$ |
| 10.8.7 | $2550/\sqrt{F_{yf}}$ | $970/\sqrt{F_{yf}}$ |
| | $\left(\dfrac{h}{t_w}\right)_{max} = \dfrac{5250}{\sqrt{F_{yf}}}$ | $\left(\dfrac{h}{t_w}\right)_{max} = \dfrac{2000}{\sqrt{F_{yf}}}$ |
| | $\left(\dfrac{h}{t_w}\right)_{max} = \dfrac{96525}{\sqrt{F_{yf}}}$ | $\left(\dfrac{h}{t_w}\right)_{max} = \dfrac{14000}{\sqrt{F_{yf}}}$ |
| | $M_n = 10^{-6}S_{xt}R_{PG}R_eF_{yt}$ | $M_n = S_{xt}R_{PG}R_eF_{yt}$ |
| | $M_n = 10^{-6}S_{xc}R_{PG}R_eF_{cr}$ | $M_n = S_{xc}R_{PG}R_eF_{cr}$ |
| | $R_{PG} = 1-0.0005a_r\left(\dfrac{h_e}{t_w}-\dfrac{5250}{\sqrt{F_{cr}}}\right)$ | $R_{PG} = 1-0.0005a_r\left(\dfrac{h_e}{t_w}-\dfrac{970}{\sqrt{F_{cr}}}\right)$ |
| | $\lambda_p = \dfrac{790}{\sqrt{F_{yf}}}$ | $\lambda_p = \dfrac{300}{\sqrt{F_{yf}}}$ |
| | $\lambda_r = \dfrac{1985}{\sqrt{F_{yf}}}$ | $\lambda_r = \dfrac{756}{\sqrt{F_{yf}}}$ |
| | $\lambda_p = \dfrac{170}{\sqrt{F_{yf}}}$ | $\lambda_p = \dfrac{65}{\sqrt{F_{yf}}}$ |
| | $\lambda_r = \dfrac{395}{\sqrt{F_{yf}}}$ | $\lambda_r = \dfrac{150}{\sqrt{F_{yf}}}$ |
| | $C_{PG} = 77200$ | $C_{PG} = 11200$ |
| | $h/t_w \leq 492\sqrt{k/F_{yw}}$ | $h/t_w \leq 187\sqrt{k/F_{yw}}$ |
| | $V_n = 0.0006A_wF_{yw}$ | $V_n = 0.6A_wF_{yw}$ |
| | $V_n = 0.0006A_wF_{yw}\left(C_v+\dfrac{1-C_v}{1.15\sqrt{1+(a/h)^2}}\right)$ | $V_n = 0.6A_wF_{yw}\left(C_v+\dfrac{1-C_v}{1.15\sqrt{1+(a/h)^2}}\right)$ |
| | $V_n = 0.0006A_wF_{yw}C_v$ | $V_n = 0.6A_wF_{yw}C_v$ |
| | $492\sqrt{k/F_{yw}} \leq h/t_w \leq 616\sqrt{k/F_{yw}}$ | $187\sqrt{k/F_{yw}} \leq h/t_w \leq 234\sqrt{k/F_{yw}}$ |
| | $C_v = \dfrac{492\sqrt{k/F_{yw}}}{h/t_w}$ | $C_v = \dfrac{187\sqrt{k/F_{yw}}}{h/t_w}$ |
| | $C_v = \dfrac{303365k}{(h/t_w)^2F_{yw}}$ | $C_v = \dfrac{44000k}{(h/t_w)^2F_{yw}}$ |
| | $h/t_w \leq 1100/\sqrt{F_{yw}}$ | $h/t_w \leq 418/\sqrt{F_{yw}}$ |
| | $0.0006\phi A_wF_{yw}C_v$ | $0.6\phi A_wF_{yw}C_v$ |
| 10.8.10 | $h_c/t_w \leq 1680/\sqrt{F_{yf}}$ | $h_c/t_w \leq 640/\sqrt{F_{yf}}$ |
| | $0.85\times10^{-3}f_c'A_c$ | $0.85f_c'A_c$ |
| | $10^{-3}A_sF_y$ | $A_sF_y$ |
| | $10^{-3}A_rF_{yr}$ | $A_rF_{yr}$ |
| | $Q_n = 0.5\times10^{-3}A_{sc}\sqrt{f_c'E_c} \leq 10^{-3}A_{sc}F_u$ | $Q_n = 0.5A_{sc}\sqrt{f_c'E_c} \leq A_{sc}F_u$ |
| | $Q_n = 0.3\times10^{-3}(t_f+0.5t_w)L_c\sqrt{f_c'E_c}$ | $Q_n = 0.3(t_f+0.5t_w)L_c\sqrt{f_c'E_c}$ |
| 10.8.11 | $R_n = 0.00625t_f^2F_{yt}$ | $R_n = 6.25t_f^2F_{yt}$ |
| | $R_n = \left(\dfrac{5k+N}{1000}\right)F_{yw}t_w$ | $R_n = (5k+N)F_{yw}t_w$ |
| | $R_n = \left(\dfrac{2.5k+N}{1000}\right)F_{yw}t_w$ | $R_n = (2.5k+N)F_{yw}t_w$ |
| | $R_n = 0.354t_w^2\left[1+3\left(\dfrac{N}{d}\right)\left(\dfrac{t_w}{t_f}\right)^{1.5}\right]\sqrt{F_{yw}t_f/t_w}$ | $R_n = 135t_w^2\left[1+3\left(\dfrac{N}{d}\right)\left(\dfrac{t_w}{t_f}\right)^{1.5}\right]\sqrt{F_{yw}t_f/t_w}$ |
| | $R_n = 0.179t_w^2\left[1+3\left(\dfrac{N}{d}\right)\left(\dfrac{t_w}{t_f}\right)^{1.5}\right]\sqrt{F_{yw}t_f/t_w}$ | $R_n = 68t_w^2\left[1+3\left(\dfrac{N}{d}\right)\left(\dfrac{t_w}{t_f}\right)^{1.5}\right]\sqrt{F_{yw}t_f/t_w}$ |
| | $R_n = \dfrac{83t_w^3}{h}\left[1+0.4\left(\dfrac{d_c/t_w}{l/b_f}\right)^3\right]$ | $R_n = \dfrac{12000t_w^3}{h}\left[1+0.4\left(\dfrac{d_c/t_w}{l/b_f}\right)^3\right]$ |
| | $R_n = \dfrac{83t_w^3}{h}\left[0.4\left(\dfrac{d_c/t_w}{l/b_f}\right)^3\right]$ | $R_n = \dfrac{12000t_w^3}{h}\left[0.4\left(\dfrac{d_c/t_w}{l/b_f}\right)^3\right]$ |
| | $R_n = \dfrac{10.76t_w^3\sqrt{F_{yw}}}{d_c}$ | $R_n = \dfrac{4100t_w^3\sqrt{F_{yw}}}{d_c}$ |
| | $R_v = 0.0007F_yd_ct_w$ | $R_v = 0.7F_yd_ct_w$ |
| | $R_v = 0.0007F_yd_ct_w\left[1.9-1.2(P_u/P_n)\right]$ | $R_v = 0.7F_yd_ct_w\left[1.9-1.2(P_u/P_n)\right]$ |
| 10.8.12 | $10^{-6}b_ft_f(d-t_f)F_{yf} \geq 0.7M_p$ | $b_ft_f(d-t_f)F_{yf} \geq 0.7M_p$ |
| | $\phi_vV_n = 0.55\times10^{-3}\phi_vF_yd_ct_p\left[1+\dfrac{3b_{cf}t_{cf}^2}{d_bd_ct_p}\right]$ | $\phi_vV_n = 0.55\phi_vF_yd_ct_p\left[1+\dfrac{3b_{cf}t_{cf}^2}{d_bd_ct_p}\right]$ |
| | $1.8\times10^{-3}F_{yb}b_ft_{bf}$ | $1.8F_{yb}b_ft_{bf}$ |
| Table 6.10.5 | $136/\sqrt{F_y}$ | $52/\sqrt{F_y}$ |
| | $\dfrac{1365}{\sqrt{F_y}}\left[1-\dfrac{1.54P_u}{\phi_bP_y}\right]$ | $\dfrac{520}{\sqrt{F_y}}\left[1-\dfrac{1.54P_u}{\phi_bP_y}\right]$ |
| | $\dfrac{500}{\sqrt{F_y}}\left[2.33-\dfrac{P_u}{\phi_bP_y}\right] \geq \dfrac{665}{\sqrt{F_y}}$ | $\dfrac{191}{\sqrt{F_y}}\left[2.33-\dfrac{P_u}{\phi_bP_y}\right] \geq \dfrac{253}{\sqrt{F_y}}$ |
| | $\dfrac{\sum Z_c(F_{yc}-P_{uc}/A_g)}{1000V_nd_b(H/[H-d_b])} \geq 1.0$ | $\dfrac{\sum Z_c(F_{yc}-P_{uc}/A_g)}{V_nd_b(H/[H-d_b])} \geq 1.0$ |
| | $P_{uc} < 0.3\times10^{-3}F_yA_g$ | $P_{uc} < 0.3F_yA_g$ |
| | $17237r_y/F_y$ | $2500r_y/F_y$ |
| | $L/r \leq 1890/\sqrt{F_y}$ | $L/r \leq 720/\sqrt{F_y}$ |
| | $8965/\sqrt{F_y}$ | $1300/\sqrt{F_y}$ |
| | $290/\sqrt{F_y}$ | $110/\sqrt{F_y}$ |
| | $2000\phi_bM_p/e$ | $2\phi_bM_p/e$ |
| | $V_y = 0.6\times10^{-3}F_ydt_w$ | $V_y = 0.6F_ydt_w$ |
| | $P_y = 10^{-3}A_gF_y$ | $P_y = A_gF_y$ |
| | $2000\phi_bM_{pa}/e$ | $2\phi_bM_{pa}/e$ |
| | $\left[1.15-0.5(P_u/V_y)(A_w/A_g)\right]1600M_p/V_y$ | $\left[1.15-0.5(P_u/V_y)(A_w/A_g)\right]1.6M_p/V_y$ |
| | $1600M_p/V_y$ | $1.6M_p/V_y$ |
| | $2600M_p/V_y$ | $2.6M_p/V_y$ |
| | $5000M_p/V_y$ | $5M_p/V_y$ |
| 10.9 | $\sqrt{(303)^2-4.39f_v^2}$ | $\sqrt{(44)^2-4.39f_v^2}$ |
| | $\sqrt{(303)^2-2.15f_v^2}$ | $\sqrt{(44)^2-2.15f_v^2}$ |
| | $\sqrt{(372)^2-3.75f_v^2}$ | $\sqrt{(54)^2-3.75f_v^2}$ |
| | $\sqrt{(372)^2-1.82f_v^2}$ | $\sqrt{(54)^2-1.82f_v^2}$ |
| | $207-1.3f_v \leq 160$ | $30-1.3f_v \leq 23$ |
| | $262-1.3f_v \leq 200$ | $38-1.3f_v \leq 29$ |
| Table 6.10.17 | $270-1.8f_v \leq 207$ | $38-1.8f_v \leq 30$ |
| | $585-1.8f_v \leq 470$ | $85-1.8f_v \leq 68$ |
| | $585-1.4f_v \leq 470$ | $85-1.4f_v \leq 68$ |
| | $730-1.8f_v \leq 580$ | $106-1.8f_v \leq 84$ |
| | $730-1.4f_v \leq 580$ | $106-1.4f_v \leq 84$ |
| | $304-1.3f_v \leq 234$ | $44-1.3f_v \leq 34$ |
| | $407-1.3f_v \leq 310$ | $59-1.3f_v \leq 45$ |
| 10.9.3 | $R_n = 2.4\times10^{-3}dtF_u$ | $R_n = 2.4dtF_u$ |
| | $R_n = 2.0\times10^{-3}dtF_u$ | $R_n = 2.0dtF_u$ |
| | $R_n = \dfrac{LtF_u}{100}$ | $R_n = LtF_u$ |
| | $R_n = 3.0\times10^{-3}dtF_u$ | $R_n = 3.0dtF_u$ |
| | $s \leq 2000P/F_ut+d/2$ | $s \leq 2P/F_ut+d/2$ |
| | $s \leq \dfrac{1000P}{\phi F_ut}+\dfrac{d}{2}$ | $s \leq \dfrac{P}{\phi F_ut}+\dfrac{d}{2}$ |
| | $L_e \leq 2000P/F_ut$ | $L_e \leq 2P/F_ut$ |
| | $L_e \leq \dfrac{1000P}{\phi F_ut}$ | $L_e \leq \dfrac{P}{\phi F_ut}$ |
| 10.9.5 | $R_n = \dfrac{A_gF_y}{1000}$ | $R_n = A_gF_y$ |
| | $R_n = \dfrac{A_nF_u}{1000}$ | $R_n = A_nF_u$ |
| | $R_n = 0.7\times10^{-3}A_gF_y$ | $R_n = 0.7A_gF_y$ |
| 10.9.8 | $F_p = \left(\dfrac{F_y-90}{20}\right)0.66d$ | $F_p = \left(\dfrac{F_y-13}{20}\right)0.66d$ |
| | $R_n = 2.0\times10^{-3}F_yA_{pb}$ | $R_n = 2.0F_yA_{pb}$ |
| | $R_n = 1.5(F_y-90)ld/20$ | $R_n = 1.5(F_y-13)ld/20$ |
### Chapter 11
In the following equations, the unit of $D$ is mm in SI unit and inch (in) in FPS unit.
| Section/Table | SI | FPS Equivalent |
| ------------- | ------------------------------------------------------------- | -------------------------------------------------------- |
| 11.6.3 | $K_3 = 0.81\left\{\dfrac{D^2+89400}{D^2+55000}\right\}$ | $K_3 = 0.81\left\{\dfrac{D^2+139}{D^2+85}\right\}$ |
| | $K_4 = 0.8+0.8Y\left\{\dfrac{D^2+89400}{D^2+55000}-1\right\}$ | $K_4 = 0.8+0.8Y\left\{\dfrac{D^2+139}{D^2+85}-1\right\}$ |
## Appendix B: Methods of Soil Exploration and Sampling
### B1 Methods of soil exploration
The detailed methods of soil investigation usually includes collecting undisturbed samples and or performing field tests. Listed below are some of the common methods of subsoil exploration.
a) **Open trial pits**: In this method trial pits are excavated exposing the subsoil thoroughly. Undisturbed samples are taken from intact sides and bottom of the trial pits. This is suitable for all types of formation but for cuts which cannot stand below water table, proper bracing shall be provided. This method is normally used for shallow depths (up to 3 m).
b) **Auger boring**: Augers, hand or power operated, are rotated and forced into soil. Augers are withdrawn and emptied when full. Soil cuttings obtained are used to interpret stratification and soil type. The method is unsatisfactory for cohesionless soils above or below ground water.
c) **Shell and auger boring**: Manual or mechanized rigs are used for vertical boring. The tools consist of auger for soft to stiff clays, shells for very stiff to hard clays, shells or sand pumps attached to sectional boring rods for sandy strata.
d) **Wash boring**: In this method, soil is loosened by chopping and cutting by impact and twisting action of a lightweight bit. Soil is removed from the borehole by a stream of water or drilling mud from lower end of the wash pipe which is worked up and down or rotated into the borehole. The water or mud flow carries the soil through the annular space between the wash pipe and casing and is overflown at ground level. The soil in suspension is allowed to settle in a pond or tank and the fluid is recirculated as required. The soil brought to surface by the wash water can be used for identification purposes but is not representative of the character and consistency of the material penetrated and the flushing water may disturb the surrounding ground. Subsoil can be identified throughly if field tests (viz. Standard Penetration Test) are performed and or undisturbed samples are collected frequently.
e) **Sounding/probing**: A number of sounding methods are available. The most common is the Standard Penetration Test (SPT)1. The SPT test is specified both in reference 1 and in ASTM D1586. Other methods include procedures like Cone Penetration Test (CPT)2 and Dynamic Probing (DP)3. Sounding/probing may be done in conjunction with inhole tests such as "Field Vane Shear Test in Cohesive Soil", (ASTM D2573), bore-hole shear (Iowa Bore-hole Shear) Test, Flat Dilatometer Test (DMT)4 or "Pressuremeter Tests in Soils", (ASTM D4719).
Numerals in the superscript in this paragraph refer to the corresponding reference materials cited in the list of references in Sec B4 in this appendix.
f) **Geophysical methods**: Geophysical survey techniques are based on determining variations in physical properties, such as electrical conductivity (resistivity), variation in density (gravimetric), magnetic susceptibility (magnetic) or velocity of sonic waves (seismic). Anomalies such as near surface disturbance (often known as noise) are common in urban environment and may limit the usefulness of geophysics in these areas. Moreover, a geophysical anomaly does not always match an engineering or geological boundary, and often there is a transition zone at a boundary. These may lead to a margin of uncertainty.
g) **Percussion boring and rotary drilling**: In percussion drilling method borehole is advanced by chopping action of a heavy bit driven by power. Water is added at the bottom of the borehole during chopping action, if ground water is not already struck. Slurry formed at the bottom of hole is removed by bailer or sand pump. Casing may be needed. In rotary drilling, borehole is advanced by power rotation of drilling bit and removal of cutting by circulating fluids which may be water, bentonite slurry or mud slurry. Casing may or may not be needed during drilling.
### B2 Choice of method
The choice of a method of soil exploration depends upon:
a) the topography, type of ground to be investigated and ground water conditions;
b) the type of building envisaged and technical requirements;
c) amount of existing information;
d) expected variability of soil;
e) external constraints such as availability of plant, access, cost and time.
The technical requirements of the investigation rather than cost should be the overriding factor in the selection of exploration method. In clayey soils, borings are suitable for deep exploration and pit for shallow exploration. In sandy soils special equipments are needed for taking representative samples below the water table. Ground investigation is normally done by boreholes, but where only shallow depths are to be investigated, and where ground water problems are not envisaged, trial pits may prove more versatile and economical. Boreholes may be necessary on waterlogged sites where it is impracticable to excavate trial pits without dewatering.
Safety aspects must be considered when selecting and carrying out exploration. Precautions relating to safety, health and welfare of workmen, hazards from underground services, contaminated ground and inspection pits or shafts shall be undertaken. Overhead power lines are a hazard if ground investigation rigs are to operate in the vicinity.
### B3 Sampling methods
Sample quality is dependent on type of soil being sampled, type and condition of equipment and the skill with which it is used. The weaker material is the most significant in an investigation, and is usually difficult to secure in an undisturbed condition. It is rarely possible to sample granular (non-cohesive) materials in undisturbed condition, unless special techniques are used. Granular soil conditions are usually assessed by in-situ tests and confirmed by disturbed samples which permit classification and grading analysis and visual inspection. Cohesive soils may be tested both in-situ and in laboratory on undisturbed or relatively undisturbed samples.
Based on assessment of the quality, samples can be classed into five categories as specified in Table B1.
**Table B1: Categories of Soil Samples Based on Quality**
| Quality | Recommended use of Sample |
| ------- | ----------------------------------------------------------------------------------- |
| Class 1 | Index test, moisture content, density, strength and deformation characteristics |
| Class 2 | Index test, moisture content, grading, density and remoulded strength in some clays |
| Class 3 | Index test and moisture content |
| Class 4 | Index test |
| Class 5 | Strata identification only |
The sample and/or test locations must be such that all changes of stratum are recorded. A number of extra samples and test results are usually required to assess variation of the properties of a stratum with depth. The record of all borings shall include the following information:
a) Size of casing (if used),
b) Number of blows per 300 mm required to drive the sampling spoon,
c) The elevation of the ground surface referred to an established datum,
d) Location and depth of boring and its relation to the proposed construction,
e) Elevation at which samples were taken,
f) Elevation of the boundaries of soil strata,
g) Description of the soil strata encountered and any particular unusual or special condition such as loss of water in the earth and rock strata, presence of boulders, cavities and obstructions, use of special type of samplers, traps, etc., and,
h) The level of ground water together with a description of how and when it was observed.
All abandoned and unsuccessful attempts of borings or drillings shall also be reported. In complex formations, details of sampling are necessary and, therefore, separate holes may be employed purely for sampling or testing, termed as double hole sampling.
Care shall be taken in protecting, handling, labelling and subsequently transporting the samples, so that samples can be received in a fit state for examination and testing, and can be correctly recognized as coming from a specific trial pit or boring.
Class 1 and Class 2 samples listed in Table B1 are generally referred to as 'undisturbed' while Classes 3, 4, and 5 as 'disturbed' samples.
a) **Disturbed samples**: These are taken by methods which modify or destroy the natural structure of the material though with suitable precaution the natural moisture content can be preserved. The amount of sample generally required for testing purposes is given in Table B2.
b) **Undisturbed samples**: These are taken by methods which preserve the structure and properties of the material. Truely undisturbed samples can not be taken from boreholes, and in practice there are only differing levels of disturbed samples. Material may be secured in open tube samplers for clays except of firm or of stiff consistency. For softer clays stationary piston samplers of low area ratio\*, shall be used and careful boring and sample preservation technique shall be employed. The minimum diameter of undisturbed sample shall be 40 mm with minimum length/diameter ratio of 3.
\* The area ratio $A_r$ is defined as the ratio of the volume of soil displacement to the volume of the collected sample, expressed as a percentage;
$$
A_r = \dfrac{D_o^2 - D_i^2}{D_i^2} \times 100
$$
where
$D_o$ = outside diameter of tube
$D_i$ = inside diameter of cutting edge.
Well designed sample tubes should have an area ratio of less than about 10 per cent.
c) **Representative samples**: These samples have all their constituent parts preserved, but may or may not be structurally disturbed.
**Table B2: Weight of Soil Sample Required for Laboratory Tests**
| Purpose of Sample | Type of Soil | Weight of Sample Required, kg. |
| -------------------------------------------------------------------------------------------- | ---------------------- | ------------------------------ |
| Soil identification, natural moisture content test, mechanical analysis and index properties | Cohesive soil | 1 |
| | Sand and gravel | 3 |
| Chemical test | Cohesive soil | 2 |
| | Sand and gravel | 3 |
| Compaction test | Cohesive soil and sand | 12.5 |
| | Gravelly soil | 25 |
| Comprehensive examination of construction materials including stabilization | Cohesive soil and sand | 25 to 50 |
| | Gravelly soil | 50 to 100 |
### B4 List of references
1. ISSMFE, TC-16, Report of the Technical Committee on Penetration Testing of Soils, International Reference Test Procedures for Standard Penetration Test; Swedish Geotechnical Society; Swedish Geotechnical Institute, Appendix B: ISSN 0281-7578 (1989)
2. ISSMFE, TC-16, Report of the Technical Committee on Penetration Testing of Soils, International Reference Test procedures for Cone Penetration Test (CPT): Swedish Geotechnical Society; Swedish Geotechnical Institute, Appendix A: ISSN 0281-7578 (1989)
3. ISSMFE, TC-16, Report of the Technical Committee on Penetration Testing of Soils, International Reference Test Procedures for Dynamic Probing (DP): Swedish Geotechnical Society; Swedish Geotechnical Institute, Appendix C: ISSN 0281-7578 (1989)
4. Merchetti, S. "In Situ Tests by Flat Dilatometer", Journal, GTE Divn., ASCE, Vol 106, GT 3, March, pp. 299-321 (1980).
## Appendix C: Guidelines for Computing the Column Interaction Diagrams
### C1 General
The interaction diagram of a given column section is drawn by assuming a series of strain distributions, each corresponding to a particular point on the interaction diagram, and computing the corresponding values of axial load $P$ and moment $M$. Once enough such points have been computed, the results are summarized on an interaction diagram.
In this appendix, the method and relationships needed to compute the various points on an interaction diagram are given based on strain compatibility and mechanics. The calculations involve the assumptions stated in Sec 6.2.3.1 through 6.2.3.7 and Sec 6.3.3.2 of Part 6.
### C2 Computation of interaction diagram
The various controlling points of an interaction diagram are shown in Fig C1.
![Fig C1: Controlling points on the interaction diagram]()
#### C2.1 Computation of Point A
The maximum usable axial load is represented by point A on the interaction diagram. The maximum axial load $\phi P_m$ shall be calculated as
$$
\phi P_m = \phi P_n(max) \tag{C 1}
$$
where $\phi P_n(max)$ is given by Eq (6.3.1) for spiral columns and by Eq (6.3.2) for tied columns.
Once $\phi P_m$ is evaluated, a horizontal straight line shall be drawn through A. This line shall mark the upper boundary of the interaction diagram.
#### C2.2 General Case
Point A' in Fig C1 represents the theoretical maximum (but not usable) axial load for a column under truly concentric loading. This theoretical maximum axial load is calculated as
$$
\phi P_o = \phi\left[0.85f_c'(A_g - A_{st}) + f_yA_{st}\right] \tag{C 2}
$$
For a symmetrical section, the corresponding moment will be zero. For unsymmetrical columns, provided the moments are taken about the geometric centroid of the section, Eq (C 10) may be used to compute the moment corresponding to $\phi P_o$.
Point E on the interaction diagram can be obtained by evaluating the moment capacity, $\phi M_o$, for pure flexure with no axial load.
While point A' is outside the interaction diagram and the portion of curve between A' and B is not usable, the solution of the general case applies for the entire curve A'BCDE.
For the purpose of this general solution, the longitudinal column bars will be considered in layers perpendicular to the plane of bending.
Layer 1 is closest to the "least compressed" surface and is at a distance $d_1$ from the "most compressed" surface. Layers 2, 3, 4 etc. are successively away from the least compressed surface and at distances $d_2, d_3, d_4$ etc. respectively from the most compressed surface.
Each strain distribution to be considered is linear with the maximum compressive strain in concrete $\varepsilon_{cu} = 0.003$. Layer 1 will have a strain $\varepsilon_{s1}$ and area $A_{s1}$, layer 2 strain $\varepsilon_{s2}$ and area $A_{s2}$ and so on. The strain distribution will be defined by setting $\varepsilon_{s1} = Z\varepsilon_y$ and $\varepsilon_{cu} = 0.003$, where $\varepsilon_y$ is the strain in steel at the onset of yield. Each strain distribution considered will correspond to a different arbitrarily chosen strain ratio $Z$, where positive values of $Z$ correspond to positive (compressive) strains. For example, $Z = -1$ corresponds to $\varepsilon_{s1} = -\varepsilon_y$, the yield strain in tension.
If $\varepsilon_{si}$ and $d_i$ are the strain in the $i$th layer of steel and the depth to that layer from the most compressed surface respectively,
$$
\varepsilon_{si} = 0.003\left(\dfrac{c-d_i}{c}\right) \tag{C 3}
$$
where $c$ is the depth of the compression zone given by
$$
c = \dfrac{0.003}{0.003-Z\varepsilon_y}d_1 \tag{C 4}
$$
Once the values of $c$ and $\varepsilon_{s1}, \varepsilon_{s2}$ and so on, are known, the stress in each layer of steel is computed as
$$
f_{si} = \varepsilon_{si}E_s \quad \text{but} \quad -f_y \leq f_{si} \leq f_y \tag{C 5}
$$
The concrete stress is uniform over the equivalent rectangular stress block having a depth $a = \beta_1c$ where $\beta_1$ is given in Sec 6.2.3.7(c).
The compressive force in concrete is given by
$$
F_c = 0.85f_c'A \tag{C 6}
$$
where $A$ is the area of the compression zone.
For a rectangular section, $A = ab$, in which $b$ is the width of the section.
For a nonrectangular section, $A$ is the area of the compression zone having a depth $a$, measured perpendicular to the neutral axis.
If $a$ is less than $d_i$ for a particular layer of steel, the force in that layer of steel is given by
$$
F_{si} = f_{si}A_{si} \tag{C 7}
$$
If $a$ is greater than $d_i$ for a particular layer of steel, the force in that layer of steel is
$$
F_{si} = (f_{si}-0.85f_c')A_{si} \tag{C 8}
$$
The axial load capacity, $P_n$ for the assumed strain distribution is obtained as
$$
P_n = F_c + \sum_{i=1}^{n}F_{si} \tag{C 9}
$$
The corresponding moment capacity, $M_n$ for an assumed strain distribution, taken about the centroid is given by
$$
M_n = F_c\bar{y} + \sum_{i=1}^{n}F_{si}(h/d-d_i) \tag{C 10}
$$
where $h$ is the overall dimension of the concrete cross-section parallel to the plane of bending, and $\bar{y}$ is the distance of the centroid of compression zone from the centroid of the section.
#### C2.3 Computation of Point C
Point C on the interaction diagram of Fig C1 corresponds to the balanced condition ($f_{s1} = f_y$ in tension) and is obtained from Eq (C 3) through (C 10) using $Z = -1$. Once $P_n$ and $M_n$ are evaluated from Eq (C 9) and (C 10), point C can be located as
$$
\phi P_b = \phi P_n \quad \text{and} \quad \phi M_b = \phi M_n
$$
in which the $\phi$ values shall be taken as follows:
$\phi = 0.7$ for tied columns, and
$\phi = 0.75$ for spiral columns.
#### C2.4 Determination of Portion BC
Portion BC of the interaction diagram can be constructed by repeated application of Eq (C 3) through (C 10) for various values of the strain ratio $Z$. The recommended sequence of strain ratios are $Z = +0.5, +0.375, +0.25, +0.125, -0.25, -0.5, -0.75$ and $-1.0$. Of these, points corresponding to $Z = 0$ (zero tension in steel), $Z = -0.25$ (maximum steel tension 25% of $f_y$), $Z = -0.5$ (maximum steel tension 50% of $f_y$) and $Z = -1.0$ (maximum steel tension $f_y$) should always be determined. The points on the curve are $(\phi M_n, \phi P_n)$ for each value of $Z$, where $\phi$ is to be taken as 0.7 for tied columns, and 0.75 for spiral columns.
Once adequate points are plotted, portion A'C can be drawn. The intersection of this curve with the horizontal line through A locates point B.
#### C2.5 Determination of Portion CD
Portion CD of the interaction diagram of Fig C1 can be obtained by taking negative values of $Z$ beyond $-1.0$, such as $Z = -1.5, -2.0, -2.5, -3.0$ and so on, and using Eq (C 3) through (C 10).
Each time the value of $\phi$ is to be taken as $\phi = 0.7$ for tied columns, and $\phi = 0.75$ for spiral columns. Once adequate points $(\phi M_n, \phi P_n)$ are plotted, the portion of curve CD (or its extension) should be drawn. The intersection of this curve with the horizontal straight line corresponding to $\phi P_n = \phi P_t$ locates the transition point D. Here, $P_t$ is the axial load capacity at the transition point D as given in Sec 6.3.5.
#### C2.6 Determination of Portion DE
Once the transition point D is located, portion DE can be drawn by using Eq (C 3) through (C 10) for negative values of $Z$ beyond $-1.0$. For this portion, however, an increased value of $\phi$ is to be used, as given in Sec 6.3.5, for the evaluation of $\phi P_n$ and $\phi M_n$. Once the portion of curve DE (or its extension) is drawn, its intersection with the abscissa ($\phi P_n = 0$) locates point E.
### C3 Interaction diagram for circular columns
Equations (C 3) through (C 10) can also be used to determine the interaction diagram of a circular column. However, this time the compression zone is a segment of a circle, of depth $a$, as shown in Fig C2.
To compute the compressive force in concrete and its moment about the centroid of the section using Eq (C 6) and (C 10), the following parameters may be helpful.
Area of the compression zone segment
$$
A = \dfrac{h^2}{4}(\theta - \sin\theta\cos\theta) \tag{C 11}
$$
Distance of centroid of the compression zone segment form the centroid of the circular section
$$
\bar{y} = \dfrac{h\sin^3\theta}{3(\theta-\sin\theta\cos\theta)} \tag{C 12}
$$
![Fig C2: Circular column section - section, strains, and stresses]()
In Eq (C 11) and (C 12), $\theta$ is half the angle subtended at the centre by the segment representing compression zone, expressed in radians.
For $a \leq h/2, \theta \leq \pi/2$
$$
\theta = \cos^{-1}\left(\dfrac{h/2-a}{h/2}\right)
$$
For $a > h/2, \theta > \pi/2$
$$
\theta = \pi - \cos^{-1}\left(\dfrac{a-h/2}{h/2}\right)
$$
The shape of the interaction diagram of circular columns is affected by the number of bars and their orientation relative to the neutral axis. For any number of bars, the interaction diagram should be determined using the least favourable bar orientation.
### C4 Unsymmetrical section
For unsymmetrical sections, with different amount of steel on opposite sides of the neutral axis, the same procedure using Eq (C 3) through (C 10) can be employed for determining the interaction diagram. However, the balanced load for positive moment will be different from that for negative moment. In a similar manner, the maximum axial load capacity, corresponding to a uniform compressive strain of 0.003 across the section, will be accompanied by a moment.
### C5 Nondimensional interaction diagrams
It may be useful to express interaction diagrams independently of column dimensions. This can be done by dividing $\phi P_n$ by $A_g$ and $\phi M_n$ by $A_gh$ and drawing the curves with $\phi M_n/(A_gh)$ as abscissa and $\phi P_n/A_g$ as ordinate. A family of such interaction diagrams for various combinations of $f_c'$ and $f_y$ with different reinforcement amounts and arrangements can be prepared to serve as design aids.
## Appendix D: Calculation of Volume Fraction of Reinforcement
The volume fraction of reinforcement in a ferrocement section can be readily calculated if the density of the mesh material and the weight of mesh per unit area are known.
For ferrocement section reinforced with expanded metal mesh, the volume fraction of mesh reinforcement may be calculated from the following relationship.
$$
V_f = \dfrac{\text{Volume of mesh}}{\text{Volume of ferrocement section}} = \dfrac{w_mN}{\gamma_mh} \times 100 \text{ per cent}
$$
where,
* $N$ = number of mesh layers
* $h$ = thickness of ferrocement section, mm
* $w_m$ = weight of mesh per unit area, N/mm²
* $\gamma_m$ = unit weight of steel, N/mm³
For ferrocement reinforced with square or rectangular mesh, the volume fraction of mesh reinforcement may be calculated from the following relationship:
$$
V_f = \dfrac{N\pi d_b^2}{4h}\left(\dfrac{1}{D_l}+\dfrac{1}{D_t}\right) \times 100 \text{ per cent}
$$
where,
* $N$ = number of layers of mesh reinforcement
* $d_b$ = diameter of mesh wire
* $h$ = thickness of ferrocement
* $D_t$ = centre to centre spacing of wires aligned transverseley in reinforcing mesh, mm
* $D_l$ = centre to centre spacing of wires aligned longitudinally in reinforcing mesh, mm
## Appendix E: Common Types and Sizes of Steel Meshes used in Ferrocement
**Table: Common Types and Sizes of Steel Meshes used in Ferrocement**
| Type | Shape | Fabrication | Mesh Size\* | Wire Gauge\* | Wire Spacing (mm) | Wire Diameter or Sheet Thickness (mm) |
| ------------------- | ----------- | --------------- | -------------------- | ------------ | ----------------- | ------------------------------------- |
| Wire mesh | Square | Woven or welded | 3/4 × 3/4 | No. 16 | 19.0 | 1.60 |
| | | | 2 × 2 | No. 19 | 13.0 | 1.00 |
| | | | 3 × 3 | No. 22 | 8.5 | 0.72 |
| | | | 4 × 4 | No. 23 | 6.4 | 0.64 |
| | | Welded | 1 × 1 | No. 14 | 25.0 | 2.00 |
| | Rectangular | Welded | 2 × 1 | No. 14 | 50 × 25 | 2.00 |
| | Hexagonal | Twisted | 1 | No. 18 | 25.0 | 1.20 |
| | | | 1 | No. 20 | 25.0 | 0.88 |
| | | | 1/2 | No. 22 | 13.0 | 0.72 |
| Expanded metal mesh | Diamond | Slit and drawn | 18 N/m² Gauge No. 18 | | | 0.58 / 1.00 |
| | | | Gauge No. 20 | | | 0.76 |
\* American wire gauge.
The source table's "Expanded metal mesh" row packs the mesh-size designation ("18 N/m²"), the two gauge callouts, and their corresponding thicknesses (0.58, 1.00, 0.76 mm) into fewer columns than the wire-mesh rows above it — the mesh has no discrete wire spacing or AWG-numbered wire gauge in the same sense as woven/welded wire mesh. The values above are transcribed in the same left-to-right order as the source table.
# Chapter 1: General Design Requirements
Source: https://docs.sayed.app/bnbc2006/part-6-structural-design/chapter-1-general-design-requirements
## 1.1 INTRODUCTION
### 1.1.1 Scope
The general requirements for the structural design of buildings, structures, and components thereof are specified in this chapter. These requirements shall apply to all buildings and structures regulated by this code. All applied loads required for structural design shall be determined in accordance with the provisions of Chapter 2. Design parameters required for the structural design of foundation elements shall conform to the provisions of Chapter 3. Design of structural members using various construction materials shall comply with the relevant provisions of Chapters 4 through 12. The FPS equivalents of the empirical expressions used throughout Part 6 are listed in Appendix A.
### 1.1.2 Definitions
The following definitions shall provide the meaning of certain terms used in this chapter.
**BASE SHEAR:** Total design lateral force or shear at the base of a structure.
**BASIC WIND SPEED:** The fastest mile wind speed in km/h, at 10 metres above the mean ground level under terrain Exposure-B defined in Sec 2.4.4 and associated with an annual probability of occurrence of 0.02.
**BEARING WALL SYSTEM:** A structural system without a complete vertical load carrying space frame.
**BRACED FRAME:** An essentially vertical truss system of the concentric or eccentric type which is provided to resist lateral forces.
**BUILDING FRAME SYSTEM:** An essentially complete space frame which provides support for gravity loads.
**CONCENTRIC BRACED FRAME (CBF):** A steel braced frame designed in conformance with Sec 10.5.17.8.
**COLLECTOR:** A member or element used to transfer lateral forces from a portion of a structure to the vertical elements of the lateral force resisting elements.
**BUILDINGS:** Structures that enclose a space and are used for various occupancies.
**DEAD LOAD:** The load due to the weight of all permanent structural and nonstructural components of a building or a structure, such as walls, floors, roofs and fixed service equipment.
**DIAPHRAGM:** A horizontal or nearly horizontal system acting to transmit lateral forces to the vertical resisting elements. The term "diaphragm" includes horizontal bracing systems.
**DUAL SYSTEM:** A combination of Moment Resisting Frames and Shear Walls or Braced Frames to resist lateral loads designed in accordance with the criteria of Sec 1.3.2.
**ECCENTRIC BRACED FRAME (EBF):** A steel braced frame designed in conformance with Sec 10.5.17.9.
**FASTEST-MILE WIND SPEED:** The highest sustained mean wind speed in km/h based on the time required for a one-mile (1.61 km) long sample of air to pass a fixed point.
**HORIZONTAL BRACING SYSTEM:** A horizontal truss system that serves the same function as a floor or roof diaphragm.
**INTERMEDIATE MOMENT RESISTING FRAME (IMRF):** A concrete moment resisting frame designed in accordance with Sec 8.3.10.
**LIVE LOAD:** The load superimposed by the use and occupancy of a building.
**MOMENT RESISTING FRAME:** A frame in which members and joints are capable of resisting forces primarily by flexure.
**ORDINARY MOMENT RESISTING FRAME (OMRF):** A moment resisting frame not meeting special detailing requirements for ductile behaviour.
**PRIMARY FRAMING SYSTEM:** That part of the structural system assigned to resist lateral forces.
**SHEARWALL:** A wall designed to resist lateral forces parallel to the plane of the wall (sometimes referred to as a vertical diaphragm or a structural wall).
**SLENDER BUILDINGS AND STRUCTURES:** Buildings and structures having a height exceeding five times the least horizontal dimension, or having a fundamental natural frequency less than 1 Hz. For those cases where the horizontal dimensions vary with height, the least horizontal dimension at mid height shall be used.
**SOFT STOREY:** Storey in which the lateral stiffness is less than 70 per cent of the stiffness of the storey above.
**SPACE FRAME:** A three-dimensional structural system without bearing walls composed of members interconnected so as to function as a complete self contained unit with or without the aid of horizontal diaphragms or floor bracing systems.
**SPECIAL MOMENT RESISTING FRAME (SMRF):** A moment resisting frame specially detailed to provide ductile behaviour complying with the requirements of Chapter 8 or 10 for concrete or steel frames respectively.
**SPECIAL STRUCTURAL SYSTEM:** A structural system not listed in Table 6.1.2 and specially designed to carry the lateral loads. See Sec 1.3.2 (e).
**STOREY:** The space between any two floor levels including the roof of a building. Storey-$x$ is the storey below level $x$.
**STOREY SHEAR, $V_x$:** The summation of design lateral forces above the storey under consideration.
**STRENGTH:** The usable capacity of an element or a member to resist the load as prescribed in these provisions.
**TERRAIN:** The ground surface roughness condition when considering the size and arrangement of obstructions to the wind.
**TOWER:** A tall, slim vertical structure.
**VERTICAL LOAD-CARRYING FRAME:** A space frame designed to carry all vertical gravity loads.
**WEAK STOREY:** Storey in which the lateral strength is less than 80 per cent of that of the storey above.
### 1.1.3 Symbols and Notation
The following symbols and notation shall apply to the provisions of this chapter:
| Symbol | Definition |
| :-------------- | :------------------------------------------------------------------------------------------------------------------------------- |
| $C$ | numerical coefficient specified in Sec 2.5.6.1 |
| $D$ | dead load on a member including self weight and weight of components, materials and permanent equipments supported by the member |
| $E$ | earthquake load |
| $E'$ | amplified earthquake load equal to $(0.375R)E$ |
| $F_i$ | lateral force applied at level-$i$ of a building |
| $F_t$ | a portion of the seismic base shear, $V$, considered concentrated at the top of the building in addition to the force $F_n$ |
| $h$ | height of a building or a structure above ground level in metres |
| $h_i, h_n, h_x$ | height in metres above ground level to level-$i$, -$n$ or -$x$ respectively |
| level-$i$ | $i$-th level of a structure above the base; $i=1$ designates the first level above the base |
| level-$n$ | upper most level of a structure |
| level-$x$ | $x$-th level of a structure above the base; $x=1$ designates the first level above the base |
| $L$ | live load due to intended use or occupancy |
| $M_x$ | overturning moment at level-$x$ |
| $V$ | the total design lateral force or shear at the base |
| $V_x$ | the storey shear at storey level-$x$ |
| $R$ | response modification coefficient for structural system given in Table 6.2.26 for seismic design |
| $T$ | fundamental period of vibration in seconds |
| $W'$ | the weight of an element or component |
| $Z$ | seismic zone coefficient given in Table 6.2.22 |
| $\Delta$ | storey lateral drift |
## 1.2 BASIC CONSIDERATIONS
### 1.2.1 General
All buildings and structures shall be designed and constructed in conformance with the provisions of this section. The buildings and portions thereof shall support all loads including dead load specified in this chapter and elsewhere in this Code. Impact, fatigue and self-straining forces shall be considered where these forces occur.
### 1.2.2 Buildings and Structures
A structure shall ordinarily be described as an assemblage of framing members and components arranged to support both gravity and lateral forces. Structures may be classified as building and non-building structures. Structures that enclose a space and are used for various occupancies shall be called buildings or building structures. Structures other than buildings, such as water tanks, bridges, communication towers, chimneys etc., shall be called non-building structures. When used in conjunction with the word building(s), the word structure(s) shall mean non-building structures, e.g. 'buildings and structures' or 'buildings or structures'. Otherwise the word 'structures' shall include both buildings and non-building structures.
### 1.2.3 Structure Importance Category
For the purpose of these provisions, buildings, structures and related equipments shall be classified into five structure importance categories as listed in Table 6.1.1, based on the level of necessity of remaining safe and functional during any post disaster period e.g. after a cyclone, or an earthquake. Each building or structure shall be placed in one of the structure importance categories and provided with a structure importance coefficient for design against wind and earthquake induced forces.
**Table 6.1.1 Structure Importance Categories**
| Structure Importance Category | General | Particular |
| :---------------------------: | :---------------------------- | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| I | Essential Facilities | 1. Hospital and other medical facilities having surgery and emergency treatment area.
2. Fire and police stations.
3. Tanks or other structures containing, housing or supporting water or other fire-suppression materials or equipment required for the protection of essential or hazardous facilities, or special occupancy structures.
4. Emergency vehicle shelters and garages.
5. Structures and equipment in emergency-preparedness centres, including cyclone and flood shelters.
6. Standby power-generating equipment for essential facilities.
7. Structures and equipment in government communication centres and other facilities required for emergency response. |
| II | Hazardous Facilities | Structures housing, supporting or containing sufficient quantities of toxic or explosive substances to be dangerous to the safety of the general public if released. |
| III | Special Occupancy Structures | 1. Covered structures whose primary occupancy is public assembly with capacity > 300 persons.
2. Buildings for schools through secondary or day-care centres with capacity > 250 students.
3. Buildings for colleges or adult education schools with capacity > 500 students.
4. Medical facilities with 50 or more resident incapacitated patients, not included above.
5. Jails and detention facilities.
6. All structures with occupancy > 5,000 persons.
7. Structures and equipment in power-generating stations and other public utility facilities not included above, and required for continued operation. |
| IV | Standard Occupancy Structures | All structures having occupancies or functions not listed above. |
| V | Low Risk Structures | Buildings and Structures that exhibit a low risk to human life and property in the event of failure, such as agricultural buildings, minor storage facilities, temporary facilities, construction facilities, and boundary walls. |
### 1.2.4 Safety
Buildings, structures and components thereof, shall be designed and constructed to support all loads, including dead loads, without exceeding the allowable stresses or specified strengths (under applicable factored loads) for the materials of construction in the structural members and connections.
### 1.2.5 Serviceability
Structural framing systems and components shall be designed with adequate stiffness to have deflections, vibration, or any other deformations within the serviceability limit of building or structure specified in this chapter.
### 1.2.6 Rationality
Structural systems and components thereof shall be designed and constructed based on rational methods which shall include, but not be limited to, the following provisions.
#### 1.2.6.1 Analysis
Analysis of the structural systems shall be made for determining the load effects on the resisting elements and connections, based on well established principles of mechanics taking equilibrium, geometric compatibility and both short and long term properties of the construction materials into account and incorporating the following:
a) **Mathematical Model:** A mathematical model of the physical structure shall represent the spatial distribution of stiffness and other properties of the structure which is adequate to provide a complete load path capable of transferring all loads and forces from their points of origin to the load-resisting elements for obtaining various load effects. For dynamic analysis, mathematical model shall also incorporate the appropriately distributed mass and damping properties of the structure adequate for the determination of the significant features of its dynamic response. A three dimensional model shall be used to represent a structure having highly irregular plan configuration such as those listed in Table 6.1.4 and having rigid or semirigid floor and roof diaphragms.
b) **Loads and Forces:** All prescribed loads and forces to be supported by the structural systems shall be determined in accordance with the applicable provisions of this chapter and Chapter 2. Loads shall be applied on the mathematical model specified in (a) above at appropriate spatial locations and along desired directions.
c) **Soil-Structure Interaction:** Soil-structure interaction effects, where required, shall be included in the analysis by appropriately including the properly substantiated properties of soil into the mathematical model specified in (a) above.
#### 1.2.6.2 Distribution of Horizontal Shear
The total lateral force shall be distributed to the various elements of the lateral force-resisting system in proportion to their rigidities considering the rigidity of the horizontal bracing systems or diaphragms.
#### 1.2.6.3 Horizontal Torsional Moments
Structural systems and components shall be designed to sustain additional forces resulting from torsion due to eccentricity between the centre of application of the lateral forces and the centre of rigidity of the lateral force resisting system. Forces shall not be decreased due to torsional effects. For accidental torsion, requirements for seismic forces shall conform to Sec 2.5.6.5.
#### 1.2.6.4 Stability Against Overturning and Sliding
Every building or structure shall be designed to resist the overturning and sliding effects caused by the lateral forces specified in this chapter.
#### 1.2.6.5 Anchorage
Anchorage of the roof to wall and columns, and of walls and columns to foundations, shall be provided to resist the uplift and sliding forces resulting from the application of the prescribed loads. Additional requirements for masonry or concrete walls shall be those given in Sec 1.7.2.7.
#### 1.2.6.6 General Structural Integrity
Buildings and structural systems shall possess general structural integrity, that is the ability to sustain local damage caused due to misuse or accidental overloading, with the structure as a whole remaining stable and not being damaged to an extent disproportionate to the original local damage.
### 1.2.7 Proportioning of Structural Elements
Structural elements, components and connections shall be proportioned and detailed based on the design methods provided in the subsequent chapters for various materials of construction, such as reinforced concrete, masonry, steel etc. to resist various load effects obtained from a rational analysis of the structural system.
### 1.2.8 Walls and Framing
Walls and structural framing shall be erected true and plumb in accordance with the design. Interior walls, permanent partitions and temporary partitions exceeding 1.8 m of height shall be designed to resist all loads to which they are subject. If not otherwise specified elsewhere in this Code, walls shall be designed for a minimum load of 0.25 kN/m² applied perpendicular to the wall surfaces. The deflection of such walls under a load of 0.25 kN/m² shall not exceed $\frac{1}{240}$ of the span for walls with brittle finishes and $\frac{1}{120}$ of the span for walls with flexible finishes. However, flexible, folding or portable partitions shall not be required to meet the above load and deflection criteria, but shall be anchored to the supporting structure.
### 1.2.9 Additions to Existing Structures
When an existing building or structure is extended or otherwise altered, all portions thereof affected by such cause shall be strengthened, if necessary, to comply with the safety and serviceability requirements provided in Sec 1.2.4 and 1.2.5 respectively.
### 1.2.10 Phased Construction
When a building or structure is planned or anticipated to undergo phased construction, structural members therein shall be investigated and designed for any additional stresses arising due to such effect.
### 1.2.11 Load Combinations and Stress Increase
Every building, structure, foundation or components thereof shall be designed to sustain, within the allowable stress or specified strength (under factored load), the most unfavourable effects resulting from various combinations of loads specified in Sec 1.5.5 and 2.7. Except otherwise permitted by Sec 1.5.5 or any other section of this Code, maximum increase in the allowable stress shall be 33% when allowable or working stress method of design is followed.
For soil stresses due to foundation loads, load combinations and stress increase specified in Sec 2.7.4 for allowable stress design method shall be used.
## 1.3 STRUCTURAL SYSTEMS
### 1.3.1 General
Every structure shall have one of the basic structural systems specified in Sec 1.3.2 or a combination thereof. The structural configuration shall be as specified in Sec 1.3.4 with the limitations imposed in Sec 1.3.5.
### 1.3.2 Basic Structural Systems
Structural systems for buildings and other structures shall be designated as one of the types listed in Table 6.1.2 and are defined as follows:
a) **Bearing Wall System:** A structural system having bearing walls or bracing systems without a complete vertical load carrying frame to support gravity loads. Resistance to lateral loads is provided by shear walls or braced frames.
b) **Building Frame System:** A structural system with an essentially complete space frame providing support for gravity loads. Resistance to lateral loads is provided by shear walls or braced frames separately.
c) **Moment Resisting Frame System:** A structural system with an essentially complete space frame providing support for gravity loads. Moment resisting frames also provide resistance to lateral load primarily by flexural action of members, and may be classified as one of the following types:
i) Special Moment Resisting Frames (SMRF)
ii) Intermediate Moment Resisting Frames (IMRF)
iii) Ordinary Moment Resisting Frames (OMRF).
The framing system, IMRF and SMRF shall have special detailings to provide ductile behaviour conforming to the provisions of Sec 8.3 and 10.5.17 for concrete and steel structures respectively. OMRF need not conform to the ductility requirements of Chapter 8 or 10.
d) **Dual System:** A structural system having a combination of the following framing systems:
i) Moment resisting frames (SMRF, IMRF or steel OMRF), and
ii) Shearwalls or braced frames.
The two systems specified in d(i) and d(ii) above shall be designed to resist the total lateral force in proportion to their relative rigidities considering the interaction of the dual system at all levels. However, the moment resisting frames shall be capable of resisting at least 25% of the applicable total seismic lateral force, even when wind or any other lateral force governs the design.
e) **Special Structural System:** A structural system not defined above nor listed in Table 6.1.2 and specially designed to carry the lateral loads, such as tube-in-tube, bundled tube, etc.
f) **Non-building Structural System:** A structural system used for purposes other than in buildings and conforming to Sec 1.5.4.8, 1.5.4.9, 2.4.6.4 and 2.5.9.
**Table 6.1.2 Basic Structural Systems and Height Limits for Seismic Zone 3**
| Basic Structural System | Lateral Force Resisting System - Description | $H$ (metres) |
| :------------------------------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :---------------------------------------------------------------------------------------------------------------------: |
| a. Bearing Wall System | 1. Light framed walls with shear panels
i) Plywood walls for structures, 3-storeys or less
ii) All other light framed walls
2. Shear walls
i) Concrete
ii) Masonry
3. Light steel-framed bearing walls with tension only bracings
4. Braced frames where bracing carries gravity loads
i) Steel
ii) Concrete (3)
iii) Heavy timber | ---
20
50
40
20
50
---
20 |
| b. Building Frame System | 1. Steel eccentric braced frame (EBF)
2. Light framed walls with shear panels
i) Plywood walls for structures 3-storeys or less
ii) All other light framed walls
3. Shear walls
i) Concrete
ii) Masonry
4. Concentric braced frames (CBF)
i) Steel
ii) Concrete (3)
iii) Heavy timber | 75
20
20
75
50
50
---
20 |
| c. Moment Resisting Frame System | 1. Special moment resisting frames (SMRF)
i) Steel
ii) Concrete
2. Intermediate moment resisting frames (IMRF), concrete (4)
3. Ordinary moment resisting frames (OMRF)
i) Steel
ii) Concrete (5) |
N.L.
N.L.
---
50
--- |
| d. Dual System | 1. Shear walls
i) Concrete with SMRF
ii) Concrete with steel OMRF
iii) Concrete with concrete IMRF (4)
iv) Masonry with SMRF
v) Masonry with steel OMRF
vi) Masonry with concrete IMRF (3)
2. Steel Eccentric Braced Frame (EBF)
i) With Steel SMRF
ii) With Steel OMRF
3. Concentric braced frame (CBF)
i) Steel with steel SMRF
ii) Steel with steel OMRF
iii) Concrete with concrete SMRF (3)
iv) Concrete with concrete IMRF (3) |
N.L.
50
50
50
50
---
N.L.
N.L.
N.L.
50
---
--- |
| e. Special Structural Systems | Structural systems not listed above | --- |
Notes: (1) Basic structural systems are defined in Sec 1.3.2. (2) $H$ = Height limit applicable to structures in Seismic Zone 3, except as permitted by Sec 1.5.4.8. (3) Prohibited in Seismic Zone 3. (4) Prohibited in Seismic Zone 3, except as permitted in Sec 2.5.9.3. (5) Prohibited in Seismic Zones 2 and 3, see Sec 1.7.2.6. N.L. = No Limit. --- = Not applicable. For Seismic Zones see Sec 2.5.4.
### 1.3.3 Combination of Structural Systems
When structural systems of Sec 1.3.2 above are combined for incorporation into the same structure, design of the combined system shall conform to the provisions of Sec 2.5.6.6.
### 1.3.4 Structural Configurations
Based on the structural configuration, each structure shall be designated as a regular, or irregular structure as defined below:
#### 1.3.4.1 Regular Structures
Regular structures have no significant physical discontinuities in plan or vertical configuration or in their lateral force resisting systems such as the irregular features described in Sec 1.3.4.2 below.
#### 1.3.4.2 Irregular Structures
Irregular structures have significant physical discontinuities in configuration or in their lateral force resisting systems. Irregular structures have either vertical irregularity or plan irregularity or both in their structural configurations.
a) **Vertical Irregularity:** Structures having one or more of the irregular features listed in Table 6.1.3 shall be designated as having a vertical irregularity.
**Exception:**
Where no storey drift ratio under design lateral force is greater than 1.3 times the storey drift ratio of the storey above, the structure may be deemed not to have irregularities of Type I or II in Table 6.1.3. For this case, the storey drifts may be calculated neglecting torsional effect and the storey drift ratio for the top two storeys need not be considered.
b) **Plan Irregularity:** Structures having one or more of the irregular features listed in Table 6.1.4 shall be designated as having a plan irregularity.
**Table 6.1.3 Vertical Irregularities of Structures**
| Type | Definition | Reference Section |
| :--: | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :---------------: |
| I | **Stiffness Irregularity (Soft Storey):** A soft storey is one in which the lateral stiffness is less than 70 per cent of that in the storey above or less than 80 per cent of the average stiffness of the three storeys above. | 2.5.5.1 |
| II | **Mass Irregularity:** Mass irregularity shall be considered to exist where the effective mass of any storey is more than 150 per cent of the effective mass of an adjacent storey. A roof which is lighter than the floor below need not be considered. | 2.5.5.1 |
| III | **Vertical Geometric Irregularity:** Vertical geometric irregularity shall be considered to exist where horizontal dimension of the lateral force-resisting system in any storey is more than 130 per cent of that in an adjacent storey, one-storey penthouses need not be considered. | 2.5.5.1 |
| IV | **In-Plane Discontinuity in Vertical Lateral Force-Resisting Element:** An in-plane offset of the lateral load-resisting elements greater than the length of those elements. | 1.5.5 |
| V | **Discontinuity in Capacity (Weak Storey):** A weak storey is one in which the storey strength is less than 80 per cent of that in the storey above. The storey strength is the total strength of all seismic-resisting elements sharing the storey shear for the direction under consideration. | 1.5.4.3, 1.3.5 |
See Sec 1.3.5(a) for the Reference Section column.
**Table 6.1.4 Plan Irregularities of Structures**
| Type | Definition | Reference Section |
| :--: | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :-----------------------------------: |
| I | **Torsional Irregularity (to be considered when diaphragms are not flexible):** Torsional irregularity shall be considered to exist when the maximum storey drift, computed including accidental torsion, at one end of the structure transverse to an axis is more than 1.2 times the average of the storey drifts of the two ends of the structure. | 1.5.4.2, 2.5.6.5, 1.5.4.3, 1.7.2.9(d) |
| II | **Reentrant Corners:** Plan configurations of a structure and its lateral force-resisting system contain reentrant corners, where both projections of the structure beyond a reentrant corner are greater than 1.5 per cent of the plan dimension of the structure in the given direction. | 1.7.2.9(d) |
| III | **Diaphragm Discontinuity:** Diaphragms with abrupt discontinuities or variations in stiffness, including those having cutout or open areas greater than 50 per cent of the gross enclosed area of the diaphragm, or changes in effective diaphragm stiffness of more than 50 per cent from one storey to the next. | 1.7.2.9(d) |
| IV | **Out-of-plane Offsets:** Discontinuities in a lateral force path, such as out-of-plane offsets of the vertical elements. | 1.5.5, 1.7.2.9(d) |
| V | **Nonparallel Systems:** The vertical lateral load-resisting elements are not parallel to or symmetric about the major orthogonal axes of the lateral force-resisting system. | 1.5.4.2 |
See Sec 1.3.5(a) for the Reference Section column.
### 1.3.5 Structural System Limitations
The following limitations shall be imposed on the use of some structural systems and configurations:
a) **Structural Irregularities:** Structures with vertical irregularity Type V as defined in Table 6.1.3 shall not be over 9.0 metres in height where the weak storey has a calculated strength of less than 65% of the storey above. However for structures, where a weak storey is capable of resisting a total seismic force of $0.375R$ times the design force prescribed in Sec 2.5.6, the above limitation shall not be applied.
Structures having irregular features described in Table 6.1.3 or 6.1.4 shall be designed in compliance with the additional requirements of the sections referenced in these Tables.
b) **Special Structural Systems:** Structural systems defined in Sec 1.3.2(e) shall be demonstrated by technical and test data to be equivalent, with regard to dynamic characteristics, lateral force resistance and energy absorption, to one of the structural systems listed in Table 6.2.24, for obtaining an equivalent $R$ value for seismic design.
## 1.4 DESIGN FOR GRAVITY LOADS
### 1.4.1 General
Design of buildings and components thereof for gravity loads shall conform to the requirements of this section. Gravity loads, such as dead load and live loads applied at the floors or roof of a building shall be determined in accordance with the provisions of Chapter 2.
### 1.4.2 Floor Design
Floor slabs and decks shall be designed for the full dead and live loads as specified in Sec 2.2 and 2.3 respectively. Floor supporting elements such as beams, joists, columns etc. shall be designed for the full dead load and the appropriately reduced live loads set forth by the provisions of Sec 2.3. Design of floor elements shall also conform to the following provisions:
a) **Uniformly Distributed Loads:** Where uniform floor loads are involved, consideration may be limited to full dead load on all spans in combination with full live load on adjacent spans and on alternate spans to determine the most unfavourable effect of stresses in the member concerned.
b) **Concentrated Loads:** Provision shall be made in designing floors for a concentrated load as set forth in Sec 2.3.3.2 applied at a location wherever this load acting upon an otherwise unloaded floor would produce stresses greater than those caused by the uniform load required therefor.
c) **Partition Loads:** Loads due to permanent partitions shall be treated as a dead load applied over the floor as a uniform line load having an intensity equal to the weight per metre run of the partitions. Loads for light movable partitions shall be determined in accordance with the provisions of Sec 2.3.3.3.
d) **Design of Members:** Floor members, such as slabs or decks, beams, joists etc. shall be designed to sustain the worst effect of the dead plus live loads or any other load combinations as specified in Sec 2.7. Where floors are used as diaphragms to transmit lateral loads between various resisting elements, those loads shall be determined following the provisions of Sec 1.7.2.9. Detailed design of the floor elements shall be performed using the procedures provided in Chapters 4 through 12 for various construction materials.
### 1.4.3 Roof Design
Roofs and their supporting elements shall be designed to sustain, within their allowable stresses or specified strength limits, all dead loads and live loads as set out by the provisions of Sec 2.2 and 2.3 respectively. Design of roof members shall also conform to the following requirements:
a) **Application of Loads:** When uniformly distributed loads are considered for the design of continuous structural members, load including full dead loads on all spans in combination with full live loads on adjacent spans and on alternate span, shall be investigated to determine the worst effects of loading. Concentrated roof live loads and special roof live loads, where applicable, shall also be considered in design.
b) **Unbalanced Loading:** Effects due to unbalanced loads shall be considered in the design of roof members and connections where such loading will result in more critical stresses. Trusses and arches shall be designed to resist the stresses caused by uniform live loads on one half of the span if such loading results in reverse stresses, or stresses greater in any portion than the stresses produced by this unit live load when applied upon the entire span.
c) **Rain Loads:** Roofs, where ponding of rain water is anticipated due to blockage of roof drains, excessive deflection or insufficient slopes, shall be designed to support such loads. Loads on roofs due to rain shall be determined in accordance with the provisions of Sec 2.6.3. In addition to the dead load of the roof, either the roof live load or the rain load, whichever is of higher intensity, shall be considered in design.
### 1.4.4 Reduction of Live Loads
The design live loads specified in Sec 2.3, may be reduced to appropriate values as permitted by the provisions of Sec 2.3.9.
### 1.4.5 Posting of Live Loads
In every building, of which the floors or parts thereof have a design live load of 3.5 kN/m² or more, and which are used as library stack room, file room, parking garage, machine or plant room, or used for industrial or storage purposes, the owner of the building shall ensure that the live loads for which such space has been designed, are posted on durable metal plates as shown in Fig 6.1.1, securely affixed in a conspicuous place in each space to which they relate. If such plates are lost, removed, or defaced, the owner shall be responsible to have them replaced.
![]()
Notes: (1) Minimum dimension of metal sign plate shall be 0.25 m. (2) Minimum size of lettering shall be 25 mm. (3) Minimum distance of the bottom of plate from the top of floor shall be 1.5 m. (4) Letterings shall be of metal embossed or cast on a metal plate. (5) Plate shall be securely affixed in a conspicuous place in each space to which it relates.
c) **Occupancy Changes:** Increase in live loads due to changes of occupancy involving loads heavier than that being designed for.
### 1.4.6 Restrictions on Loading
The building owner shall ensure that the live load for which a floor or roof is or has been designed, will not be exceeded during its use.
### 1.4.7 Special Considerations
In the absence of actual dead and live load data, the minimum values of these loads shall be those specified in Sec 2.2 and 2.3. In addition, special consideration shall be given to the following aspects of loading and due allowances shall be made in design if occurrence of such loading is anticipated after construction of a building:
a) **Increase in Dead Load:** Actual thickness of the concrete slabs or other members may become larger than the designed thickness due to movements or deflections of the formwork during construction.
b) **Future Installations:** Changes in the numbers, types and positions of partitions and other installations may increase actual load on the floors of a building.
### 1.4.8 Deflection and Camber
The deflection and camber requirements shall be those specified in the relevant sections of Chapters 4 through 12 for structural design using various materials.
## 1.5 DESIGN FOR LATERAL LOADS
### 1.5.1 General
Every building, structure or portions thereof shall be designed to resist the lateral load effects, such as those due to wind or earthquake forces, in compliance with the requirements prescribed in this section.
### 1.5.2 Selection of Lateral Force for Design
Any of the lateral loads prescribed in Chapter 2, considered either alone or in combination with other forces, whichever produces the most critical effect, shall govern the design. However, the structural detailing requirements shall comply with those prescribed in Sec 1.7. When a dual structural system is used to resist lateral loads, design shall also conform to Sec 1.3.2(d).
### 1.5.3 Design for Wind Load
Design of buildings and their components to resist wind induced forces shall comply with the following requirements:
#### 1.5.3.1 Direction of Wind
Structural design for wind forces shall be based on the assumption that wind may blow from any horizontal direction.
#### 1.5.3.2 Design Considerations
Design wind load on the primary framing systems and components of a building or structure shall be determined on the basis of the procedures provided in Sec 2.4 considering the basic wind speed, shape and size of the building, and the terrain exposure condition of the site. For slender buildings and structures, dynamic response characteristics, such as fundamental natural frequency, shall be determined for calculating the gust response coefficient. Load effects, such as forces, moments, deflections etc. on various components of the building due to wind shall be determined from a static analysis of the structure as specified in Sec 1.2.6.1.
#### 1.5.3.3 Shielding Effect
Reductions in wind pressure on buildings and structures due to apparent shielding effects of the up wind obstructions, such as man made constructions or natural terrain features, shall not be permitted.
#### 1.5.3.4 Dynamic Effects
Dynamic wind forces such as that from along-wind vibrations caused by the dynamic wind-structure interaction effects, as set forth by the provisions of Sec 2.4.6.6, shall be considered in the design of regular shaped slender buildings. For other dynamic effects such as cross-wind or torsional responses as may be experienced by buildings or structures having unusual geometrical shapes (i.e. vertical or plan irregularities listed in Tables 6.1.3 and 6.1.4), response characteristics, or site locations, structural design shall be made based on the information obtained either from other reliable references or from wind-tunnel test specified in Sec 1.5.3.5 below, complying with the other requirements of this section.
#### 1.5.3.5 Wind Tunnel Test
Properly conducted wind-tunnel tests shall be required for those buildings or structures having unusual geometric shapes, response characteristics, or site locations for which cross-wind response such as vortex shedding, galloping etc. warrant special consideration, and for which no reliable literature for the determination of such effects is available. This test is also recommended for those buildings or structures for which more accurate wind-loading information is desired than those given in this section and in Sec 2.4.
Tests for the determination of mean and fluctuating components of forces and pressures shall be considered to be properly conducted only if the following requirements are satisfied:
a) The natural wind has been modelled to account for the variation of wind speed with height,
b) The intensity of the longitudinal components of turbulence has been taken into consideration in the model,
c) The geometric scale of the structural model is not more than three times the geometric scale of the longitudinal component of turbulence,
d) The response characteristics of the wind tunnel instrumentation are consistent with the measurements to be made, and
e) The Reynolds number is taken into consideration when determining forces and pressures on the structural elements.
Tests for the purpose of determining the dynamic response of a structure shall be considered to be properly conducted only if requirements (a) through (e) above are fulfilled and, in addition, the structural model is scaled with due consideration to length, distribution of mass, stiffness and damping of the structure.
#### 1.5.3.6 Wind Loads During Construction
Buildings, structures and portions thereof under construction, and construction structures such as formwork, staging etc. shall be provided with adequate temporary bracings or other lateral supports to resist the wind load on them during the erection and construction phase.
#### 1.5.3.7 Masonry Construction in High-Wind Regions
Design and construction of masonry structures in high-wind regions shall conform to the requirements of Sec 4.9.
#### 1.5.3.8 Height Limits
Unless otherwise specified elsewhere in this Code, no height limits shall be imposed, in general, on the design and construction of buildings or structures to resist wind induced forces.
### 1.5.4 Design for Earthquake Forces
Design of structures and components thereof to resist the effects of earthquake forces shall comply with the requirements of this section. One- and two-family dwellings in Seismic Zone 1 need not conform to the provisions of this section.
#### 1.5.4.1 Basic Design Consideration
For the purpose of earthquake resistant design, each structure shall be placed in one of the seismic zones as given in Fig 6.2.8 and assigned with a structure importance category as set forth in Sec 1.2.3. The seismic forces on structures shall be determined considering seismic zoning, site soil characteristics, structural systems and configurations, height and dynamic properties of the structure as provided in Sec 2.5. The structural system and configuration types for a building or a structure shall be determined in accordance with the provisions of Sec 1.3. Other seismic design requirements shall be those specified in this section.
#### 1.5.4.2 Requirements for Directional Effects
For the purpose of these provisions, the seismic forces on any building or structure shall be assumed to act non-concurrently in the direction of each principal axis of the building or structure. The structural design shall also conform to the following requirements:
a) In Seismic Zones 2 and 3, provision shall be made for the effects of seismic forces acting in directions other than the principal axes under each of the following circumstances:
i) The structure has plan irregularity Type V as given in Table 6.1.4.
ii) The structure has plan irregularity Type I as given in Table 6.1.4 for both major axes.
iii) A column of a structure forms part of two or more intersecting lateral force resisting systems except if the axial load in the column due to seismic forces acting in either direction is less than 20 per cent of the allowable column axial load.
b) The requirement that orthogonal effects be considered may be satisfied by designing such elements for 100 per cent of the prescribed seismic forces in one direction plus 30 per cent of the prescribed forces in the perpendicular direction. The combination requiring the greater component strength shall be used for design. Alternatively, the effects of the two orthogonal directions may be combined on a square-root-of-the-sum-of-the-squares (SRSS) basis. When the SRSS method of combining directional effects is used, each term computed shall be assigned with the sign that will result in the most conservative result.
Also when amplified earthquake load, $E'$ is used in the load combinations stipulated in Sec 2.7.5.2 for design of steel structures using LFD method, orthogonal effects need not be considered.
#### 1.5.4.3 Structural Configuration Requirements
Structures shall be designated as being regular or irregular based on their structural configurations defined in Sec 1.3.4.
For structures in Seismic Zone 1 and for those in Seismic Zone 2 with Structure Importance Categories IV and V, only cases with vertical irregularity Type V (Table 6.1.3) and plan irregularity Type I (Table 6.1.4) need to be evaluated for seismic resistant design. All other structures having irregularities listed in Tables 6.1.3 and 6.1.4 shall be designed to meet the additional requirements of the Code sections referred to in those tables.
#### 1.5.4.4 Methods of Analysis
Earthquake forces and their effects on various structural elements shall be determined by using either a static analysis method or a dynamic analysis method whichever is applicable based on the limitations set forth in Sec 2.5.5.1 and conforming to Sec 1.2.6.1.
#### 1.5.4.5 Minimum Design Seismic Force
The minimum design seismic forces shall be those determined in accordance with the Sec 2.5.6 except as modified by Sec 2.5.7.2(c) when dynamic response method of analysis is used.
#### 1.5.4.6 Distribution of Seismic Forces
The total lateral seismic forces and moments shall be distributed among various resisting elements at any level and along the vertical direction of a building or structure in accordance with the provisions of Sec 2.5.6 unless otherwise determined by dynamic analysis or modified by Sec 2.5.7.2.
#### 1.5.4.7 Vertical Components of Seismic Forces
The effects of the vertical component of the seismic ground motion on structural components shall be determined in accordance with the following provisions:
a) **Requirements for Seismic Zone 3:** In Seismic Zone 3, effects of vertical ground motion on horizontal cantilevers and prestressed concrete elements shall be considered as follows:
i) Horizontal cantilevers shall be designed for an upward seismic force of $0.20W'$.
ii) In addition to all other load combinations, horizontal prestressed concrete elements shall be designed using a maximum of 50% of dead load as gravity load alone or in combination with other lateral load effects.
b) **Dynamic Analysis:** The vertical seismic response of structures or structural elements may also be determined using the dynamic response methods provided in Sec 2.5.7 based on the vertical components of ground motion as specified in Sec 2.5.7.1(d). However, the response used in design shall not be less than that obtained by the static procedure specified in (a) above.
#### 1.5.4.8 Height Limits
Limits shall be placed on the heights of various structural systems in Seismic Zone 3 as set forth in Table 6.1.2 with the exceptions given below. Other requirements on height limits shall be those provided in Sec 2.5.6.6.
**Exception:**
Regular structures may exceed the height limits specified in Table 6.1.2 by not more than 50 per cent under the following conditions:
a) Unoccupied structures which are not accessible to the general public
b) Other structures when technical data is submitted in accordance with Sec 1.3.5(b).
#### 1.5.4.9 Non-building Structures
Seismic lateral force on non-building structures shall be determined in accordance with the provisions of Sec 2.5.9. Other design requirements shall be those provided in this chapter.
### 1.5.5 Overturning Requirements
Every structure shall be designed to resist the overturning effects caused by wind or earthquake forces specified in Sec 2.4 and 2.5 respectively. The overturning moment $M_x$ at any storey level-$x$ of a building shall be determined as:
$$
M_x = F_t \left( h_n - h_x + \sum_{i=1}^{n} F_i \right) (h_i - h_x) \tag{1.5.1}
$$
where,
| Symbol | Definition |
| :-------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| $h_i, h_x, h_n$ | Height in metres at level-$i$, -$x$ or -$n$ respectively. |
| $F_i$ | Lateral force applied at level-$i$, $i=1$ to $n$. |
| $F_t$ | Concentrated lateral force applied at level-$n$ in addition to $F_n$ applicable for earthquake only as defined in Sec 2.5.6. For all other lateral load cases, $F_t = 0$. |
At any level, the increment of overturning moment shall be distributed to the various resisting elements in the same manner as the distribution of horizontal shear prescribed in Sec 2.5.6.4. Overturning effects on every element shall be carried down to the foundation level. Also, the following requirements shall be fulfilled:
a) Redistribution of overturning effects may be made to other vertical members if framing members of sufficient strength and stiffness are provided to transmit the required loads.
b) In Seismic Zones 2 and 3, where a lateral force resisting element is discontinuous, such as for vertical irregularity Type IV in Table 6.1.3 or for plan irregularity Type IV in Table 6.1.4, columns supporting such elements, when designed using strength design method, shall have the strength to resist the axial force resulting from the following load combinations, (i) and (ii) in addition to all other applicable load combinations specified in Sec 2.7.5.
i) $1.0D + 0.8L + (0.375R)E$
ii) $0.85D \pm (0.375R)E$
When working stress design method is used, strength of such columns may be determined by using an allowable stress increase of 70%.
In addition, the design shall conform to the following provisions:
i) The axial forces in such columns need not exceed the designed capacity of other elements of the structure transferring these loads to the column.
ii) For construction in Seismic Zones 2 and 3, such columns shall meet the detailing requirements or member limitations given in Sec 8.3 and 10.5.17 for reinforced concrete and steel respectively. Such columns shall also meet the requirements of Sec 1.8.4 for overturning moments to be resisted at the foundation-soil interface.
c) At foundation level, the base overturning moment for the entire structure or for any one of its lateral load-resisting elements, shall not exceed two-thirds of the dead load resisting moment. The weight of the earth superimposed over footings may be used to calculate the dead load resisting moment.
### 1.5.6 Drift and Building Separation
#### 1.5.6.1 Storey Drift Limitation
Storey drift is the displacement of one level relative to the level above or below due to the design lateral forces. Except otherwise permitted in Sec 1.3.4.2(a) calculated storey drift shall include both translational and torsional deflections and conform to the following requirements:
a) Storey drift, $\Delta$, shall be limited as follows:
i) $\Delta \leq 0.04h/R \leq 0.005h$ for $T < 0.7$ second.
ii) $\Delta \leq 0.03h/R \leq 0.004h$ for $T \geq 0.7$ second.
iii) $\Delta \leq 0.0025h$ for unreinforced masonry structures.
where, $h$ = height of the building or structure.
The period $T$ used in this calculation shall be the same as that used for determining the base shear in Sec 2.5.6. The limits involving $R$ in (i) and (ii) above shall be applicable only when earthquake forces are present.
b) The drift limits set out in (a) above may be exceeded where it can be demonstrated that greater drift can be tolerated by both structural and nonstructural elements without affecting life safety.
#### 1.5.6.2 Building Separation
All components of a structure shall be designed and constructed to act as an integral unit unless they are separated structurally by a distance sufficient to avoid contact under the most unfavourable condition of deflections due to lateral loads. For seismic loads, the separation shall be at least $0.375R$ times the maximum drift due to design seismic forces.
### 1.5.7 P-Delta Effects
The resulting member forces and moments and the storey drifts induced by P-Delta effects need not be considered when the ratio of secondary moment to primary moment remains within 0.10. The ratio may be evaluated for any storey as the product of the total dead and live loads above the storey and the lateral drift in that storey divided by the product of the storey shear in that storey and the height of that storey.
In Seismic Zone 3, P-Delta effects need not be considered where the storey drift ratio does not exceed $0.02/R$.
### 1.5.8 Uplift Effects
Uplift effects caused due to lateral loads shall be considered in design. When allowable (working) stress method is used for design, dead loads used to reduce uplift shall be multiplied by a factor of 0.85.
## 1.6 DESIGN FOR MISCELLANEOUS LOADS
### 1.6.1 General
Buildings, structures and components thereof, when subject to loads other than dead, live, wind and earthquake loads, shall be designed in accordance with the provisions of this section. Miscellaneous loads, such as those due to temperature, rain, flood and surge etc. on buildings or structures, shall be determined in accordance with Sec 2.6. Structural members subject to miscellaneous loads, not specified in Sec 2.6 shall be designed using well established methods given in any reliable references, and complying with the other requirements of this Code.
### 1.6.2 Self-Straining Forces
Self-straining forces such as those arising due to assumed differential settlements of foundations and from restrained dimensional changes due to temperature, moisture, shrinkage, creep, and similar effects, shall be taken into consideration in the design of structural members.
### 1.6.3 Stress Reversal and Fatigue
Structural members and joints shall be investigated and designed against possible stress reversals caused due to various construction loads. Where required, allowance shall be made in the design to account for the effects of fatigue. The allowable stress may be appropriately reduced to account for such effects in the structural members.
### 1.6.4 Flood and Surge Resistant Design
Buildings, structures and components thereof shall be designed, constructed and anchored to resist flotation, collapse or any permanent movement due to loads including flood or surge. Structural members shall be designed to resist both hydrostatic and significant hydrodynamic loads and effects of buoyancy resulting from flood or surge. Flood and surge loads on buildings and structures shall be determined in accordance with Sec 2.6.4. Load combination including flood and surge loads shall conform to Sec 2.7. Design of foundations to sustain these load effects shall conform to the provisions of Sec 1.8.
Stability against overturning and sliding caused due to wind and flood or surge loads simultaneously shall be investigated, and such effects shall be resisted with a minimum factor of safety of 1.5, considering dead load only.
## 1.7 DETAILED DESIGN REQUIREMENTS
### 1.7.1 General
All structural framing systems shall comply with the requirements of this section. Only the elements of the designated lateral force resisting systems can be used to resist design lateral forces specified in Chapter 2. The individual components shall be designed to resist the prescribed forces acting on them. Design of components shall also comply with the specific requirements for the materials contained in Chapters 4 through 12. In addition, such framing systems and components shall comply with the design requirements provided in this section.
### 1.7.2 Structural Framing Systems
The basic structural systems are defined in Sec 1.3.2 and shown in Table 6.1.2, and each type is subdivided by the types of framing elements used to resist the lateral forces. Special framing requirements are given in the following sections in addition to those provided in Chapters 4 through 12.
#### 1.7.2.1 Detailing Requirements for Combinations of Structural Systems
For components common to different structural systems, a more restrictive detailing shall be provided.
#### 1.7.2.2 Connections to Resist Seismic Forces
Connections which resist prescribed seismic forces shall be designed in accordance with the seismic design requirements provided in Chapters 4 through 12. Detailed sketches for these connections shall be given in the structural drawings.
#### 1.7.2.3 Deformation Compatibility
All framing elements not required by design to be part of the lateral force resisting system, shall be investigated and shown to be adequate for vertical load carrying capacity when displaced $0.375R$ times the displacements resulting from the seismic lateral forces. For designs using working stress methods, this capacity may be determined using an allowable stress increase of 70 per cent. P-Delta effects on such elements shall be accounted for.
a) **Adjoining Rigid Elements:** Moment resisting frames may be enclosed or adjoined by more rigid elements which would tend to prevent a space frame from resisting lateral forces where it can be shown that the action or failure of the more rigid elements will not impair the vertical and lateral load resisting ability of the space frame.
b) **Exterior Elements:** Exterior nonbearing, non-shearwall panels or elements which are attached to or enclose the exterior of a structure, shall be designed to resist the forces according to Eq (2.5.10) of Chapter 2 if seismic forces are present, and shall accommodate movements of the structure resulting from lateral forces or temperature changes. Such elements shall be supported by structural members or by mechanical connections and fasteners joining them to structural members in accordance with the following provisions:
i) Connections and panel joints shall allow for a relative movement between storeys of not less than two times the storey drift caused by wind forces, $0.375R$ times the storey drift caused by design seismic forces, or 12 mm, whichever is greater.
ii) Connections to permit movement in the plane of the panel for storey drift shall be either sliding connections using slotted or oversized holes, connections which permit movement by bending of steel, or other connections providing equivalent sliding and ductility capacity.
iii) Bodies of connections shall have sufficient ductility and rotation capability to preclude any fracture of the anchoring elements or brittle failures at or near weldings.
iv) Bodies of the connection shall be designed for 1.33 times the seismic force determined by Eq (2.5.10) of Chapter 2, or equivalent.
v) All fasteners in the connection system, such as bolts, inserts, welds, dowels etc. shall be designed for 4 times the forces determined by Eq (2.5.10) of Chapter 2, or equivalent.
vi) Fasteners embedded in concrete shall be attached to, or hooked around reinforcing steel, or otherwise terminated so as to transfer forces to the reinforcing steel effectively.
#### 1.7.2.4 Ties and Continuity
a) All parts of a structure shall be interconnected. These connections shall be capable of transmitting the prescribed lateral force to the lateral force resisting system. As a minimum, any smaller portions of a building or structure shall be tied to the remainder of the building or the structure with elements having the strength to transfer at least $Z/3$ times the weight of the smaller portion.
b) A positive connection for resisting a horizontal force acting parallel to the member shall be provided for each beam, girder, or truss. This force shall be not less than $Z/5$ times the sum of the dead and live load tributary to the member.
#### 1.7.2.5 Collector Elements
Collector elements shall be provided which are capable of transferring the lateral forces originating in other portions of the structure to the element providing the resistance to those forces.
#### 1.7.2.6 Concrete Frames
When concrete frames are provided by design to be part of the lateral force resisting system, they shall conform to the following provisions:
a) In Seismic Zone 3 these frames shall be designed as special moment resisting frames (SMRF).
b) In Seismic Zone 2 they shall, as a minimum, be intermediate moment resisting frames (IMRF).
#### 1.7.2.7 Anchorage of Concrete and Masonry Walls
Concrete and masonry walls shall be anchored to all floors and roofs which provide lateral support for the wall. The anchorage shall provide a positive direct connection between the wall and floor or roof and shall be capable of resisting the horizontal forces specified in Sec 2.5.8, or a minimum force of 3.0 kN per linear metre of wall, whichever is greater. Walls shall be designed to resist bending between anchors where the anchor spacing exceeds 1.2 m. In masonry walls of hollow units or cavity walls, anchors shall be embedded in a reinforced grouted structural element of the wall. Deformations of the floor and roof diaphragms shall be considered in the design of the supported walls and the anchorage forces in the diaphragms shall be determined in accordance with Sec 1.7.2.9 below.
#### 1.7.2.8 Boundary Members
Specially detailed boundary members shall be considered for shearwalls and shearwall elements whenever their design is governed by flexure.
#### 1.7.2.9 Floor and Roof Diaphragms
Deflection in the plane of the diaphragm shall not exceed the permissible deflection of the attached elements. Permissible deflection shall be that deflection which will permit the attached element to maintain its structural integrity under the individual loading and continue to support the prescribed loads. Design of diaphragms shall also comply with the following requirements.
a) **Diaphragm Forces:** Diaphragms shall be designed to resist the seismic forces given in Sec 2.5.8.3 or for similar non-seismic lateral forces, whichever is greater.
b) **Diaphragm Ties:** Diaphragms supporting concrete or masonry walls shall have continuous ties, or struts between the diaphragm chords to distribute the anchorage forces specified in Sec 1.7.2.7 above. Added chords may be provided to form sub-diaphragms to transmit the anchorage forces to the main cross ties.
c) **Wood Diaphragms:** Where wood diaphragms are used to laterally support concrete or masonry walls, the anchorage shall conform to Sec 1.7.2.7 above. In seismic Zones 2 and 3 the following requirements shall also apply:
i) Anchorage shall not be accomplished by use of toe nails or nails subject to withdrawal, nor shall wood ledgers or framing be used in cross-grain bending or cross-grain tension.
ii) The continuous ties required by paragraph (b) above, shall be in addition to the diaphragm sheathing.
d) **Structures in Seismic Zone 3**
i) For structures in Seismic Zone 3 having a plan irregularity of Types I, II, III or IV in Table 6.1.4 connections of diaphragms to the vertical elements and to collector elements and connections of collector elements to the vertical elements shall be designed without any increase in allowable stresses for elements resisting the lateral forces.
ii) For structures having a plan irregularity of Type II in Table 6.1.4, diaphragm chords and collectors shall be designed considering independent movement of any projecting wings of the structure. Each of these diaphragm elements shall be designed for the more severe of the following cases:
1. Motion of the projecting wings in the same direction.
2. Motion of the projecting wings in opposing directions.
**Exception:**
This requirement may be deemed to be satisfied if the procedures of Sec 2.5.7 when seismic forces are present, in conjunction with a three dimensional model, have been used to determine the lateral seismic forces for design.
#### 1.7.2.10 Framing Below the Base
When structural framings continue below the base, the following requirements shall be satisfied.
a) **Framing between the Base and the Foundation:** The strength and stiffness of the framing between the base and the foundation shall not be less than that of the superstructure. The special detailing requirements of Sec 8.3 or 10.4, as appropriate for reinforced concrete or steel, shall apply to columns supporting discontinuous lateral force resisting elements and to SMRF, IMRF, and EBF system elements below the base which are required to transmit the forces resulting from lateral loads to the foundation.
b) **Foundations:** The foundation shall be capable of transmitting the design base shear and the overturning forces from the superstructure into the supporting soil, but the short term dynamic nature of the loads may be taken into account in establishing the soil properties. Sec 1.8 below, prescribes the additional requirements for specific types of foundation construction.
## 1.8 FOUNDATION DESIGN REQUIREMENTS
### 1.8.1 General
The design and construction of foundation, foundation components and connection between the foundation and superstructure shall conform to the requirements of this section and applicable provisions of Chapter 3 and other portions of this Code.
### 1.8.2 Soil Capacities
The bearing capacity of the soil, or the capacity of the soil-foundation system including footing, pile, pier or caisson and the soil, shall be sufficient to support the structure with all prescribed loads, considering the settlement of the structure. For piles, this refers to pile capacity as determined by pile-soil friction and bearing which may be determined in accordance with the provisions of Chapter 3. For the load combination including earthquake, the soil capacity shall be sufficient to resist loads at acceptable strains considering both the short time loading and the dynamic properties of the soil. The stress and settlement of soil under applied loads shall be determined based on established methods of Soil Mechanics.
### 1.8.3 Superstructure-to-Foundation Connection
The connection of superstructure elements to the foundation shall be adequate to transmit to the foundation the forces for which the elements are required to be designed.
### 1.8.4 Foundation-Soil Interface
For regular buildings, the lateral force $F_t$ considered for earthquake, may be omitted when determining the overturning moment developed at the foundation-soil interface. The base overturning moments for the entire structure or for any one of its lateral force-resisting elements, shall not exceed two-thirds of the dead load resisting moment. The weight of the earth superimposed over footings may be used to calculate the dead load resisting moment.
### 1.8.5 Special Requirements for Footings, Piles and Caissons in Seismic Zones 2 and 3
#### 1.8.5.1 Piles and Caissons
Piles and caissons shall be designed for flexure whenever the top of such members is anticipated to be laterally displaced by earthquake motions. The criteria and detailing requirements of Sec 8.3 for concrete and Sec 10.5.17 for steel shall apply for a length of such members equal to 120 per cent of the flexural length.
#### 1.8.5.2 Footing Interconnection
a) Footings and pile caps shall be completely interconnected by strut ties or other equivalent means to restrain their lateral movements in any orthogonal direction.
b) The strut ties or other equivalent means as specified in (a) above, shall be capable of resisting in tension or compression a force not less than 10% of the larger footing or column load unless it can be demonstrated that equivalent restraint can be provided by frictional and passive soil resistance or by other established means.
### 1.8.6 Retaining Wall Design
Retaining walls shall be designed to resist the lateral pressure of the retained material, under drained or undrained conditions and including surcharge, in accordance with established engineering practice. For such walls, the minimum factor of safety against base overturning and sliding due to applied earth pressure shall be 1.5.
## 1.9 DESIGN AND CONSTRUCTION REVIEW
Every building or structure designed shall have its design documents prepared in accordance with the provisions of Sec 1.9.1. The minimum requirements for design review and construction observation shall be those set forth under Sec 1.9.2 and 1.9.3 respectively.
### 1.9.1 Design Document
The design documents shall be prepared and signed by the engineer responsible for the structural design of any building or structure intended for construction. The design documents shall include a design report, and a set of structural drawings, which shall be prepared in compliance with Sec 1.9.1.1 and 1.9.1.2 below for submittal to the concerned authority. For the purpose of this provision, the concerned authority shall be either persons from the government approval agency for the construction, or the owner of the building or the structure, or one of his representatives.
#### 1.9.1.1 Design Report
The design report shall contain the description of the structural design with basic design information as provided below, so that any other structural design engineer will be able to independently verify the design parameters and the member sizes using these basic information. The design report shall include, but not be limited to, the following:
a) Name and governing edition of this Code and other referenced standards, and the specific portions, stating chapter, section, clause etc. of these Code and standards including any specialist report used for the structural design.
b) Methods used for the calculation of all applied loads along with basic load coefficients and other basic information including any assumption or judgement made under special circumstances.
c) A drawing of the complete mathematical model prepared in accordance with Sec 1.2.6.1(a) to represent the structure and showing on it the values, locations and directions of all applied loads, and location of the lateral load resisting systems such as shearwalls, braced frames etc.
d) Methods of structural analysis, and results of the analysis such as shear, moment, axial force etc., used for proportioning various structural members and joints including foundation members.
e) Methods of structural design including types and strength of the materials of construction used for proportioning the structural members.
f) Reference of the soil report or any other documents used in the design of the structure, foundation or components thereof.
g) Statement supporting the validity of the above design documents with date and signature of the engineer responsible for the structural design.
h) When computer programs are used, to any extent, to aid in the analysis or design of the structure, the following items, in addition to items (a) through (g) above, shall be required to be included in the design report:
i) A sketch of the mathematical model used to represent the structure in the computer generated analysis.
ii) The computer output containing the date of processing, program identification, identification of structures being analysed, all input data, units and final results. The computer input data shall be clearly distinguished from those computed in the program.
iii) A program description containing the information necessary to verify the input data and interpret the results to determine the nature and extent of the analysis and to check whether the computations comply with the provisions of this Code.
iv) The first sheet of each computer run shall be signed by the engineer responsible for the structural design.
#### 1.9.1.2 Structural Drawings
The structural drawings shall include, but not be limited to, the following:
a) The first drawing sheet shall contain: (1) identification of the project to which the building or the structure, or portion thereof belongs, (2) reference to the design report specified in Sec 1.9.1.1 above, (3) date of completion of design, and (4) identification and signature with date of the engineer responsible for the structural design.
b) Drawing sheets, other than the first, shall include structural details of the elements of the structure clearly showing all sizes, cross-sections and relative locations, connections, reinforcements, laps, stiffeners, welding types, lengths and locations etc. whichever is applicable for a particular construction. Floor levels, column centres and offset etc., shall be dimensioned. Camber of trusses and beams, if required, shall be shown on drawings. For bolt connected members, connection types such as slip, critical, tension or bearing type, shall be indicated on the drawing.
c) Drawings shall be prepared to a scale large enough to show the information clearly and the scales shall be marked on the drawing sheets. Each drawing sheet shall be provided with the design specifications including material types and strength, clear cover and development lengths of reinforcements, or any other design parameter relevant to the member or connection details provided in that drawing sheet. Each drawing sheet shall also contain the signature with date of the engineer responsible for the structural design.
### 1.9.2 Design Review
The design documents specified in Sec 1.9.1 shall be available for review when required by the concerned authority. Review shall be accomplished by an independent structural engineer qualified for this task and appointed by the concerned authority. Design review shall be performed through independent calculations, based on the information provided in the design documents prepared and signed by the original structural design engineer, to verify the design parameters including applied loads, methods of analysis and design, and final design dimensions and other details of the structural elements. The reviewing engineer shall also check the sufficiency and appropriateness of the supplied structural drawings for construction.
### 1.9.3 Construction Observation
Construction observation shall be performed by a responsible person who will be a competent professional appointed by the owner of the building or the structure. Construction observation shall include, but not be limited to, the following:
a) Specification of an appropriate testing and inspection schedule prepared and signed with date by the responsible person;
b) Review of testing and inspection reports; and
c) Regular site visit to verify the general compliance of the construction work with the structural drawings and specifications provided in Sec 1.9.1.2(b) above.
# Chapter 10: Steel Structures
Source: https://docs.sayed.app/bnbc2006/part-6-structural-design/chapter-10-steel-structures
## 10.1 SCOPE
This chapter provides the requirements for the use of structural steel in general building construction including the use of hot rolled steel sections and steel tubes. The provisions are generally applicable to riveted, bolted and welded constructions.
Two types of design procedures are covered: Working Stress Design (WSD) method and Load Factor Design (LFD) method.
## 10.2 DEFINITIONS AND NOTATION
### 10.2.1 Definitions
For the purpose of this chapter the following definitions shall apply.
**BUCKLING LOAD:** The load at which a member or a structure as a whole collapses or buckles in a load test.
**EFFECTIVE LATERAL RESTRAINT:** Restraint which provides sufficient resistance against buckling of the compression flange of a loaded strut, beam or girder to either side at the point of its application.
**ELASTIC CRITICAL MOMENT:** The elastic moment which will initiate yielding or cause buckling.
**FACTOR OF SAFETY:** The factor by which the yield stress of the material of a member is divided to get the permissible stress of that material.
**GAUGE:** The transverse spacing between parallel adjacent lines of fasteners.
**MAIN MEMBER:** A structural member which is primarily responsible for carrying and distributing the applied load.
**PITCH:** The centre to centre distance between individual fasteners in a line.
**SECONDARY MEMBER:** A member provided for stability and for restraining the main member from buckling.
### 10.2.2 Notation
Symbols used in this chapter shall have the following meaning unless otherwise defined elsewhere in this chapter.
* A = cross-sectional area, mm²
* Ap = loaded area of concrete, mm²
* Ab = nominal body area of a fastener, mm²
* Ar = area of an upset rod based upon the major diameter of its threads, mm²
* Ac = area of effective concrete flange in composite design, mm²
* Ac' = area of concrete, mm²
* Af = area of compression flange, mm²
* Af = area of flange, mm²
* Afe = effective tension flange area, mm²
* Afg = gross area of beam flange, mm²
* Afn = net flange area of beam, mm²
* Ag = gross area, mm²
* Ans = net area subject to shear, mm²
* App = projected bearing area, mm²
* Ar = area of reinforcing bars, mm²
* As = area of steel beam in composite design, mm²
* As' = area of compressive reinforcing steel, mm²
* Asc = cross-sectional area of stud shear connector, mm²
* Asy = area of reinforcing steel providing composite action at point of negative moment, mm²
* Ast = cross-sectional area of a stiffener or pair of stiffeners, mm²
* Asl = area of link stiffener, mm²
* Avf = shear area on the failure path, mm²
* At = net tension area, mm²
* Av = net shear area, mm²
* Aw = web area, mm²
* Aw = effective area of weld, mm²
* Awl = link web area, mm²
* Az = area of steel bearing concentrically on a concrete support, mm²
* Az2 = total cross-sectional area of a concrete support, mm²
* B = factor for bending stress in web-tapered members
* B1, B2 = factors used in determining Mn for combined bending and axial forces when first order analysis is employed
* Ca = numerical coefficient
* Cb = bending coefficient dependent upon moment gradient
* Cc = column slenderness ratio separating elastic and inelastic buckling
* Ci = slenderness ratio of compression elements
* Cm = coefficient applied to bending term in interaction equation for prismatic members and dependent upon column curvature caused by applied moments
* Cm' = coefficient applied to bending term in interaction equation for tapered members and dependent upon axial stress at the small end of the member
* Cpg = plate girder coefficient
* Cp = stiffness factor for primary member in a flat roof
* Cs = stiffness factor for secondary member in a flat roof
* Cp = ratio of "critical" web stress, according to the linear buckling theory, to the shear yield stress of web material
* Cw = warping constant, mm⁶
* C1 = increment used in computing minimum spacing of oversized and slotted holes
* C2 = increment used in computing minimum edge distance for oversized and slotted holes
* D = outside diameter of tubular member, mm
* D = factor depending upon type of transverse stiffeners used
* D = dead load due to self weight and permanent elements on the structure
* E = modulus of elasticity of steel (200,000 N/mm²)
* E = earthquake load (see Sec 2.7)
* E' = amplified earthquake load (see Sec 2.7)
* Ec = modulus of elasticity of concrete, N/mm²
* Em = modified modulus of elasticity, N/mm²
* Fa = axial compressive stress permitted in a prismatic member in the absence of moment, N/mm²
* Fay = axial compressive stress permitted in a tapered member in the absence of moment, N/mm²
* Fb = bending stress permitted in a prismatic member in the absence of axial force, N/mm²
* Fby = bending stress permitted in a tapered member in the absence of axial force, N/mm²
* FBM = nominal strength of base material to be welded, N/mm²
* FEXX = classification strength of weld metal, N/mm²
* Fb' = allowable bending stress in compression flange of plate girders as reduced for hybrid girders or because of large web depth to thickness ratio, N/mm²
* Fbx, Fby = bending stress permitted in a prismatic member in the absence of axial force about x and y axes respectively, N/mm²
* Fcr = critical stress, N/mm²
* Fe = elastic buckling stress, N/mm²
* Fe' = euler stress for a prismatic member divided by factor of safety, N/mm²
* Fex = elastic flexural buckling stress about the major axis, N/mm²
* Fey = elastic flexural buckling stress about the minor axis, N/mm²
* Fet = elastic torsional buckling stress, N/mm²
* Fmy = modified yield stress for composite column, N/mm²
* Frn = nominal shear rupture strength, N/mm²
* Fr = compressive residual stress in flange, N/mm²
* Fp = allowable bearing stress, N/mm²
* Fsy = St. Venant torsion resistance bending stress in a tapered member, N/mm²
* Ft = allowable axial tensile stress, N/mm²
* Fu = specified minimum tensile strength of the type of steel or fastener being used, N/mm²
* Fv = allowable shear stress, N/mm²
* Fw = nominal strength of weld electrode material, N/mm²
* Fwy = flange warping torsion resistance bending stress in a tapered member, N/mm²
* Fy = specified minimum yield stress of the type of steel being used, N/mm²
* Fyb = specified minimum yield stress of beam, N/mm²
* Fyc = specified minimum column yield stress, N/mm²
* Fyf = specified minimum yield stress of flange, N/mm²
* Fym = yield stress obtained from mill test reports or from physical tests, N/mm²
* Fyp = specified minimum yield stress of the longitudinal reinforcing bars, N/mm²
* Fys = static yield stress, N/mm²
* Fyst = specified minimum yield stress of stiffener, N/mm²
* Fyw = specified minimum yield stress of the web, N/mm²
* G = shear modulus of elasticity of steel (77220 N/mm²)
* H = average storey height above and below a beam to column connection, mm
* Hs = length of a stud shear connector after welding, mm
* I = moment of inertia, mm⁴
* Id = moment of inertia of steel deck supported on secondary members, mm⁴ per m
* Ieff = effective moment of inertia of composite sections for deflection computations, mm⁴
* Ip = moment of inertia of primary members, mm⁴
* Is = moment of inertia of secondary members, mm⁴
* Ist = moment of inertia of steel beam in composite construction, mm⁴
* Ist = moment of inertia of a transverse stiffener, mm⁴
* Itr = moment of inertia of transformed composite section, mm⁴
* Ix, Iy = moment of inertia about the principal axes, mm⁴
* Jc = torsional constant for a section, mm⁴
* K = effective length factor for prismatic member
* Ks = slip coefficient
* Kt = effective length factor for torsional buckling
* Ky = effective length factor for a tapered member
* L = unbraced length of tensile members, mm
* Lb = unbraced length of member measured between centre of gravity of the bracing members, mm
* Lbr = length of bracing member, mm
* Lc = distance in line of force from centre of a standard or oversized hole or from the centre of the end of a slotted hole to an edge of a connected part, mm
* Lo = live load due to occupancy and moveable equipment
* Lp = limiting laterally unbraced length for full plastic bending capacity, uniform moment case (Cb=1.0), mm
* Lpd = limiting laterally unbraced length for plastic analysis, mm
* Lr = limiting laterally unbraced length for inelastic lateral-torsional buckling, mm
* Ls = length of secondary member in flat roof framing, m
* Lspace = column spacing perpendicular to direction of girder, mm
* M = moment, kNm
* Mn = nominal flexural strength of a member or joint, kNm
* Mp = plastic bending moment, kNm
* Mpc = plastic bending moment modified by axial load ratio, kNm
* Mu = required flexural strength of member or joint, kNm
* Muy = required flexural strength about the y-axis, kNm
* M1 = smaller moment at end of unbraced length of beam - column
* M2 = larger moment at one end of three-segment proportion of a tapered member
* M2' = larger moment at end of unbraced length of beam - column
* Mmax = maximum moment in three adjacent segments of a tapered member
* Mcr = elastic buckling moment, kNm
* Mlt = required flexural strength in member due to lateral frame translation, kNm
* Mn' = nominal flexural strength, kNm
* Mn', Mmy = flexural strength for use in alternate interaction equations for combined bending and axial force, kNm
* Mnt = required flexural strength in member assuming there is no lateral translation of the frame, kNm
* Mp' = plastic bending moment, kNm
* Mny' = moment for use in alternate interaction equations for combined bending and axial force, kNm
* Mr = limiting buckling moment, Mcr when λ = λr, Cb = 1.0, kNm
* Mu = required flexural strength, kNm
* My = initial yield bending moment, kNm
* N = length of bearing, mm
* Np = number of stud shear connectors on a beam in one transverse rib of a metal deck
* N1 = number of shear connectors required between point of maximum moment and point of zero moment
* N2 = number of shear connectors required between concentrated load and point of zero moment
* P = axial load, kN
* Pb = force transmitted by a fastener to the critical part, kN
* Pf = factored axial load, kN
* Pn = normal force, kN
* Pn/Vn = ratio of required axial force Pu to nominal shear strength Vn of a link
* Pbf = factored beam flange or connection plate force in a restrained connection, kN
* Pcr = maximum strength of an axially loaded compression member or beam, kN
* Pd = required axial strength of a column resulting from application of dead load, kN
* Pe = euler buckling load, kN
* Pel = elastic buckling load, kN
* Pe' = required axial strength of a column resulting from application of the amplified earthquake load E'
* Pl = required axial strength of a column resulting from application of live load L, kN
* Pn = nominal axial strength (tension or compression), kN
* Ppb = bearing load on concrete, kN
* Pu = required axial strength of a column or a link, kN
* Pse = required axial strength of a column based on load combination with seismic loads, kN
* Py = nominal yield axial strength of a member, Py = 10 FyAg, kN
* Qf = full reduction factor for slender compression elements
* Qs = ratio of effective profile area of an axially loaded member to its total profile area
* Qs' = reduction factor for slender stiffened compression elements
* Qsc = nominal strength of one stud shear connector, kN
* Qs = axial stress reduction factor where width-thickness ratio of unstiffened elements exceeds noncompact section limits
* R = reaction or concentrated load applied to beam or girder, kN
* R = earthquake response modification coefficient for structural system given in Table 6.2.24 of Chapter 2, Loads
* RN = nominal strength of a member
* RPG = plate girder bending strength reduction factor
* Rz = hybrid girder factor
* Rn = nominal resistance, kN
* Rv = web shear strength, kN
* S = spacing of secondary members in a flat roof, m
* S = elastic section modulus, mm³
* Seff = governing slenderness ratio of tapered member
* (Sx)eff = effective section modulus corresponding to partial composite action, mm³
* Sx, Sxc = elastic section modulus about major axis, mm³
* Sx = elastic section modulus referred to tension and compression flanges respectively, mm³
* Sx = elastic section modulus about major axis
* Sy = section modulus of steel beam used in composite design referred to the bottom flange, mm³
* Sxc = section modulus of transformed composite section referred to the bottom flange, based upon maximum permitted effective width of concrete flange, mm³
* T = factored applied tension force per bolt, kN
* Tb = specified pretension load in a high-strength bolt, kN
* Up, Us = ponding stress index for primary and secondary members
* V = shear force, kN
* Vf = friction force, kN
* Vh = total horizontal shear to be resisted by connectors under full composite action, kN
* Vhp = total horizontal shear provided by the connectors providing partial composite action, kN
* Vn = nominal shear strength, kN
* Vu = required shear strength, kN
* Vnl = nominal shear strength of an active link, kN
* Vind = nominal shear strength of a member modified by the axial load magnitude, kN
* X1, X2 = beam buckling factors
* Y = ratio of yield stress of web steel to yield stress of stiffener steel
* Z = plastic section modulus, mm³
* Zb = plastic section modulus of beam, mm³
* Zc = plastic section modulus of column, mm³
* a = clear distance between transverse stiffeners, mm
* a = distance between connectors in a built-up member, mm
* a = dimension parallel to the direction of stress, mm
* a = shortest distance from edge of pin hole to edge of member measured parallel to direction of force, mm
* a' = distance beyond theoretical cut-off point required at ends of welded partial length cover plate to develop stress, mm
* aw = ratio of web area to compression flange area
* b = actual width of stiffened and unstiffened compression elements, mm
* b = dimension normal to the direction of stress, mm
* bdf = column flange width, mm
* be = effective width of stiffened compression element, mm
* be' = reduced effective width for slender compression elements, mm
* beff = effective edge distance, mm
* bf = flange width, mm
* c1, c2, c3 = numerical coefficients
* d = depth of beam or girder, mm
* dr = diameter of a roller or rocker bearing, mm
* db = pin or roller diameter, mm
* db = nominal diameter of a fastener, mm
* db = overall beam depth, mm
* dc = web depth clear of fillets, mm
* dco = overall column section depth, mm
* dL = depth at the larger end of a tapered member, mm
* ds = depth at the smaller end of a tapered member or unbraced segment thereof, mm
* dpz = overall panel zone depth between continuity plates, mm
* e = EBF link length, mm
* fa = axial compression stress on member based on effective area, N/mm²
* fc = computed compressive stress in the stiffened element, N/mm²
* fa = computed axial stress, N/mm²
* fau = computed axial stress at the smaller end of a tapered member or unbraced segment thereof, N/mm²
* fb = computed bending stress, N/mm²
* fb1 = smallest computed bending stress at one end of a tapered segment, N/mm²
* fb2 = largest computed bending stress at one end of a tapered segment, N/mm²
* fbl = computed bending stress at the large end of a tapered member or unbraced segment thereof, N/mm²
* fbx, fby = computed bending stress in axes x and y respectively, N/mm²
* fc' = specified compressive strength of concrete, N/mm²
* ft = computed tensile stress, N/mm²
* fun = required normal stress, N/mm²
* fuw = required shear stress, N/mm²
* fvs = computed shear stress, N/mm²
* fws = shear between girder web and transverse stiffeners per linear mm of single stiffener or pair of stiffeners, N
* g = transverse centre to centre spacing (gauge) of any two consecutive holes, mm
* gc = clear distance between flanges of a beam or girder, mm
* hc = assumed web depth for stability, mm
* hr = nominal rib height for steel deck, mm
* ht, hw = factors for web tapered members
* im = factor for minimum moment of inertia for a transverse stiffener
* k = distance from outer face of flange to web toe of fillet of rolled shape, mm
* kc = web plate buckling coefficient
* ks = compression element restraint coefficient
* kw = shear buckling coefficient for girder webs
* l = actual unbraced length of a member, mm
* l' = unsupported length of lacing bar, mm
* l" = largest laterally unbraced length along either flange at the point of load, mm
* lbr = length of bearing, mm
* lb = actual unbraced length in plane of bending, mm
* lcr = critical unbraced length in plane of bending, mm
* m = ratio of web to flange yield stress or critical stress in hybrid beams
* n = modular ratio (Ec/Es)
* q = allowable horizontal shear to be resisted by a shear connector, kN
* r = radius of gyration, mm
* rb = radius of gyration about axis of concurrent bending, mm
* rn = radius of gyration about axis of concurrent bending at the smaller end of a tapered member or unbraced segment thereof, mm
* rl = minimum radius of gyration of individual component in a built-up member, mm
* rm = radius of gyration of the steel shape, pipe or tubing in composite columns
* rs = radius of gyration at the smaller end of a tapered member, mm
* ro = polar radius of gyration about the shear centre, mm
* rsx, rsy = radius of gyration about x and y axes at the smaller end of a tapered member respectively, mm
* rT = radius of gyration of a section comprising the compression flange plus 3/4 of the compression web area, taken about an axis in the plane of the web, mm
* rT0 = radius of gyration at the smaller end of a tapered member or unbraced segment thereof, considering only the compression flange plus 3/4 of the compression web area, taken about an axis in the plane of the web, mm
* rx, ry = radius of gyration about the x and y axes respectively, mm
* s = longitudinal centre to centre spacing (pitch) of any two consecutive holes, mm
* t = compression element thickness, mm
* t = thickness of an element part, mm
* t = wall thickness of a tubular member, mm
* t = thickness of connected part, mm
* tc = thickness of the critical part, mm
* tfc = flange thickness, mm
* tp = thickness of beam flange or moment connection plate at rigid beam to column connection, mm
* tpf = thickness of beam flange, mm
* tcf = thickness of column flange, mm
* tf = flange thickness, mm
* tp = thickness of panel zone including doubler plates, mm
* tw = web thickness, mm
* twc = column web thickness, mm
* tpz = thickness of panel zone (doubler plate not necessarily included), mm
* w = length of channel shear connectors, mm
* wc = unit weight of concrete, kN/m³
* wr = average width of rib or haunch of concrete slab on formed steel deck, mm
* wp = width of panel zone between column flanges, mm
* xo, yo = coordinates of shear centre with respect to the centroid, mm
* z = distance from the smaller end of a tapered member, mm
* Δsh = translation deflection of the storey under consideration, mm
* η = depth tapering ratio
* ηy, ζ = exponents for alternate beam-column interaction equation
* λ = slenderness parameter
* λc = column slenderness parameter
* λc = equivalent slenderness parameter
* λeff = effective slenderness ratio
* λp = limiting slenderness parameter for compact element
* λr = limiting slenderness parameter for noncompact element
* ϕ = resistance factor
* ϕb = resistance factor for flexure
* ϕc = resistance factor for compression
* ϕcc = resistance factor for axially loaded composite columns
* ϕgf = resistance factor for shear on the failure path
* ϕt = resistance factor for tension
* ϕv = resistance factor for shear
* ϕw = resistance factor for welds
* μ = coefficient of friction
## 10.3 MATERIAL
### 10.3.1 Structural Steel
Material conforming to one of the following standard specifications is approved for use under the provisions of this Code:
* BDS 878: Specification for Weldable Structural Steels.
* ASTM A36/A36M: Standard Specification for Structural Steel.
* ASTM A53: Standard Specification for Pipe, Steel, Black and Hot-dipped, Zinc-coated Welded and Seamless.
* ASTM A242/A242M: Specification for High-strength Low-alloy Structural Steel.
* ASTM A441: Standard Specification for High-strength Low-alloy Structural Manganese Vanadium Steel.
* ASTM A500: Standard Specification for Cold-formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes.
* ASTM A501: Standard Specification for Hot-formed Welded and Seamless Carbon Steel Structural Tubing.
* ASTM A514/A514M: Standard Specification for High-yield Strength, Quenched and Tempered Alloy Steel Plate, Suitable for Welding.
* ASTM A529/A529M: Standard Specification for Structural Steel with 42 ksi (290 MPa) Minimum Yield Point (1/4 in (13 mm) Maximum Thickness).
* ASTM A570/A570M: Standard Specification for Steel, Sheet and Strip, Carbon, Hot-rolled, Structural Quality.
* ASTM A572/A572M: Standard Specification for High-strength Low-alloy Columbium-Vanadium Steel of Structural Quality.
* ASTM A588/A588M: Standard Specification for High-strength Low-alloy Structural Steel with 50 ksi (345 MPa) Minimum Yield Point to 4 in (100 mm) Thick.
* ASTM A606: Standard Specification for Steel, Sheet and Strip, High-strength, Low-alloy, Hot-rolled and Cold-rolled, with Improved Atmospheric Corrosion Resistance.
* ASTM A607: Standard Specification for Steel, Sheet and Strip, High-strength, Low-alloy, Columbium or Vanadium, or Both, Hot-rolled and Cold-rolled.
* ASTM A618: Standard Specification for Hot-formed Welded and Seamless High-strength Low-alloy Structural Tubing.
* ASTM A852: Quenched and Tempered Low-alloy Structural Steel Plate with 70 ksi Minimum Yield Strength to 4 in (100 mm) Thick.
Certified mill test reports or certified reports of tests made by the fabricator or a testing laboratory in accordance with ASTM A6 or A568, as applicable, shall constitute sufficient evidence of conformity with one of the above standards. If requested, the fabricator shall provide an affidavit stating that the structural steel furnished meets the requirements of the grade specified.
### 10.3.2 Rivets, Bolts, Washers and Nuts
Unidentified steel may be used for unimportant members or details where the precise physical properties and weldability of the steel would not affect the strength of the structure, provided the surface conditions are acceptable according to the criteria specified in ASTM A6.
Steel rivets shall conform to ASTM A502: Standard Specification for Steel Structural Rivets.
Steel bolts shall conform to one of the following standards:
* ASTM A307: Standard Specification for Carbon Steel Bolts and Studs, 60,000 psi Tensile Strength.
* ASTM A325: Standard Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength.
* ASTM A449: Standard Specification for Quenched and Tempered Steel Bolts and Studs.
* ASTM A490: Standard Specification for Heat-treated Steel Structural Bolts, 150 ksi Minimum Tensile Strength.
* ASTM A563: Standard Specification for Carbon and Alloy Steel Nuts.
* ASTM F436: Standard Specification for Hardened Steel Washers.
A449 bolts are permitted only in connections requiring bolt diameters greater than 38 mm and shall not be used in slip-critical connections.
Manufacturer's certification may be accepted as sufficient evidence of conformity with the standards.
### 10.3.3 Anchor Bolts and Threaded Rods
Anchor bolt and threaded rod shall conform to one of the following standards:
* ASTM A36: Standard Specification for Structural Steel.
* ASTM A194/A194M: Standard Specification for Carbon and Alloy Steel Nuts for Bolts for High-pressure and High-temperature Service.
* ASTM A354: Standard Specification for Quenched and Tempered Alloy Steel Bolts, Studs and Other Externally Threaded Fasteners.
* ASTM A449: Standard Specification for Quenched and Tempered Steel Bolts and Studs.
* ASTM A588/A588M: Standard Specification for High-Strength Low alloy Structural Steel with 50 ksi (345 MPa) Minimum Yield Point to 4 in (100 mm) Thick.
* ASTM A687: Standard Specification for High-strength Non-headed Steel Bolts and Studs.
Threads on bolts and rods shall conform to Unified Standard Series of latest edition of ANSI B18.1 and shall have Class 2A tolerances.
A449 material is acceptable for high-strength anchor bolts and threaded rods of any diameter.
Manufacturer's certification may be accepted as sufficient evidence of conformity with the standards.
### 10.3.4 Welds
Welding electrodes and fluxes shall conform to one of the following specifications of the American Welding Society:
* AWS A5.1: Specification for Covered Carbon Steel Arc Welding Electrodes.
* AWS A5.5: Specification for Low-alloy Steel Covered Arc Welding Electrodes.
* AWS A5.17: Specification for Carbon Steel Electrodes and Fluxes for Submerged-arc Welding.
* AWS A5.18: Specification for Carbon Steel Filler Metals for Gas-shielded Arc Welding.
* AWS A5.20: Specification for Carbon Steel Electrodes for Flux-cored Arc Welding.
* AWS A5.23: Specification for Low-alloy Steel Electrodes and Fluxes for Submerged-arc Welding.
* AWS A5.28: Specification for Low-alloy Steel Filler Metals for Gas-shielded Arc Welding.
* AWS A5.29: Specification for Low-alloy Steel Electrodes for Flux-cored Arc Welding.
Manufacturer's certification may be accepted as sufficient evidence of conformity with the standards.
### 10.3.5 Stud Shear Connectors
Steel stud shear connectors shall conform to the requirements of AWS D1.1: Structural Welding Code-Steel.
Manufacturer's certification may be accepted as sufficient evidence of conformity with the above standard.
## 10.4 TYPES OF CONSTRUCTION
Two basic types of construction and associated design assumptions are permissible both for Working Stress Design method and Load Factor Design method under the conditions stated herein. Each type of construction will govern in a specific manner the size of members and the types and strength of their connections. Both types of construction must comply with the stability requirements of Sec 10.5.2.
a) Type FR, fully restrained construction, commonly designated as "rigid-frame" (continuous frame), assumes that beam to column connections have sufficient rigidity to hold the original angles between intersecting members virtually unchanged.
b) Type PR, partially restrained construction, assumes that the connections of beams and girders do not have enough rigidity to hold the original angles between intersecting members virtually unchanged.
The design of all connections shall be consistent with the assumptions as to the type of construction assumed in the analysis.
The use of PR construction depends on the evidence of predictable proportion of full end restraint. Where the connection restraint is ignored, i.e for "simple framing," it is assumed that under gravity loads the ends of the beams and girders are connected for shear only and are free to rotate. For "simple framing" the following requirements shall apply:
a) The connections and connected members shall be adequate to carry the gravity loads as simply supported beams.
b) The connections and connected members shall be adequate to resist the lateral loads.
c) The connections shall have sufficient inelastic rotation capacity to avoid overload of fasteners or welds under combined gravity and lateral loading.
When the rotational restraint of the connections is used in the design of the connected members or for the stability of the structure as a whole, the capacity of the connection for such restraint must be established by analytical or empirical means.
## 10.5 FRAMES AND OTHER STRUCTURES
### 10.5.1 General
In addition to meeting the requirements of member strength and stiffness, frames and other continuous structures shall be designed to provide the needed deformation capacity and overall frame stability.
### 10.5.2 Frame Stability
Stability shall be provided for the whole structure and for each compression element.
Considerations shall be given to P-Delta effects resulting from deflected shape of the structure or of individual elements of the lateral load resisting system.
#### 10.5.2.1 Braced Frames
In frames where lateral stability is provided by diagonal bracing, shear walls or equivalent means, the effective length factor K for compression members shall be taken as unity, unless structural analysis shows that a smaller value may be used.
The vertical bracing system for a braced multi-storey frame shall be adequate to prevent buckling and maintain the lateral stability of the structure, including the overturning effects of drift, under the design loads specified in Sec 10.7.2.4 or 10.8.2.4 as the case may be.
The vertical bracing system for a multi-storey frame may be considered to function together with shear walls, floor and roof slabs, which are properly secured to the structural frames. The columns, girders, beams and diagonal members, when used as the vertical bracing system, may be considered to comprise a simply connected vertical cantilever truss in the analyses for frame buckling and lateral instability. Axial deformation of all members in the vertical bracing system shall be included in the lateral stability analysis.
Girders and beams included in the vertical bracing system of a braced multi-storey frame shall be proportioned for axial force and moment caused by concurrent horizontal and gravity loads.
#### 10.5.2.2 Unbraced Frames
In frames where lateral stability depends upon the bending stiffness of rigidly connected beams and columns, the effective length factor K of compression members shall be determined by structural analysis and shall not be less than unity.
Analysis of unbraced multi-story frames shall include the effects of frame instability and column axial deformation under the design loads specified in Sec 10.7.2.4 or 10.8.2.4 as the case may be.
In plastic design the axial force in the columns caused by the combination of gravity and lateral loads specified in Sec 10.8.2.4 shall not exceed 0.75A\g\F\y\.
## 10.6 DESIGN REQUIREMENTS
### 10.6.1 Gross Area
The gross area A\g\ of a member at any point is the sum of the products of the thickness and the gross width of each element as measured normal to the axis of the member.
### 10.6.2 Net Area
The net area A\n\ of a member is the sum of the products of the thickness and the net width of each element computed as follows:
For a chain of holes extending across a part in any diagonal or zigzag line, the net width of the part shall be obtained by deducting from the gross width the sum of the diameters or slot dimensions as provided in Sec 10.9.3.2 of all holes in the chain, and adding, for each gauge space in the chain, the quantity s²/4g.
The width of a bolt or rivet hole shall be taken as 1.50 mm greater than the nominal dimension of the hole.
For angles, the gauge for holes in opposite adjacent legs shall be taken as the sum of the gauges from the back of the angles less the thickness.
The net area of the part is obtained from that chain which gives the least net width.
In determining the net area across plug or slot welds, the weld metal shall be ignored.
### 10.6.3 Effective Net Area
When the load is transmitted directly to each of the cross-sectional elements by connectors, the effective net area A\e\ is equal to the net area A\n\.
When the load is transmitted by bolts or rivets through some but not all of the cross-sectional elements of the member, the effective net area A\e\ shall be computed as:
$$
A_e = UA_n
$$
(10.6.1)
When the load is transmitted by welds through some but not all of the cross-sectional elements of the member, the effective net area A\e\ shall be computed as:
$$
A_e = UA_g
$$
(10.6.2)
where
U = reduction coefficient.
Unless a larger coefficient can be justified by tests or other rational means the following values of U shall be used:
* W, M or S shapes with flange widths not less than 2/3 the depth, and structural tees cut from these shapes, with connection to the flanges. Bolted or riveted connections shall have at least three fasteners per line in the direction of stress. U = 0.90
* W, M or S shapes not meeting the above conditions, structural tees cut from all shapes including built-up cross-sections. Bolted or riveted connections shall have at least three fasteners per line in the direction of stress. U = 0.85
* All members with bolted or riveted connections having only two fasteners per line in the direction of stress. U = 0.75
When load is transmitted by transverse welds to some but not all of the cross-sectional elements of W, M or S shapes and structural tees cut from these shapes, A\e\ shall be taken as the area of the directly connected elements.
When the load is transmitted to a plate by longitudinal welds along both edges at the end of the plate, the length of the welds shall not be less than the width of the plate. The effective net area A\e\ shall be computed by Eq (10.6.2).
Unless a larger coefficient can be justified by tests or other rational means the following values of U shall be used:
i) When l > 2w: U = 1.00
ii) When 2w > l > 1.5w: U = 0.87
iii) When 1.5w > l > w: U = 0.75
where
l = weld length, mm
w = plate width (distance between welds), mm
### 10.6.4 Rotational Resistance at Points of Support
At the points of support, beams, girders and trusses shall be restrained against rotation about their longitudinal axis.
Bolted and riveted splice and gusset plates and other connection fittings subject to tensile force shall be designed in accordance with the provisions of Sec 10.7.4.1, where the effective net area shall be taken as the actual net area, except that, for the purpose of design calculations, it shall not be taken more than 85% of the gross area.
**Note:** The hot rolled shapes described as W, M or S are specified in ASTM A6/A6M: Standard Specification for General Requirements for Rolled Steel Plates, Shapes, Sheet Piling, and Bars for Structural Use.
### 10.6.5 Limiting Slenderness Ratios
For compression members, the slenderness ratio Kl/r shall not exceed 200. If this limit is exceeded, the allowable stress shall not be more than the value obtained from Eq (10.7.2).
For tension members the slenderness ratio L/r should preferably not exceed 300. The above limitation shall not be applicable to rods in tension. Members which have been designed to perform as tension members in a structural system, but experience some compression loading, need not satisfy the compression slenderness limit.
### 10.6.6 Simple Spans
Beams, girders and trusses designed as simply supported spans shall have an effective length equal to the distance between centres of gravity of the members to which they deliver their end reactions.
### 10.6.7 End Restraint
When full or partial end restraint due to continuous, semi-continuous or cantilever action is considered in the design of beams, girders and trusses as well as the sections of the members to which they connect, these shall be designed to carry the shears and moments introduced due to the restraint, in addition to all other forces. The stresses developed shall not exceed at any point the unit stresses prescribed in Sec 10.7.4 through 10.7.6, except that some nonelastic but self-limiting deformations of a part of the connections is permitted when this is essential to avoid overstressing of fasteners.
## 10.7 WORKING STRESS DESIGN METHOD
### 10.7.1 General
This section provides the specifications for the design and construction of steel buildings using Working Stress Design method.
### 10.7.2 Basis of Design
#### 10.7.2.1 Allowable Stress
All structural members, connections and connectors shall be designed so that the stresses due to the service loads and their combinations stipulated in Sec 10.7.2.4 do not exceed the allowable stresses specified in Sec 10.7.4 through 10.7.11 and Sec 10.9. The allowable stresses specified in these sections do not apply to peak stresses in regions of connections (see Sec 10.6.7) for which requirements of Sec 10.7.11 are to be satisfied.
#### 10.7.2.2 Stress Increase
The maximum permissible increase in the allowable stress shall be 33% when produced by wind or seismic loading, acting alone or in combination with the service dead and live loads as given in Sec 10.7.2.4 provided the required section shall not be less than that required for the service dead and live loads computed without the 33% stress increase.
#### 10.7.2.3 Structural Analysis
The stresses in members, connections and connectors shall be determined by elastic analysis for the service loads and their combinations specified in Chapter 2, Loads.
#### 10.7.2.4 Loads and Load Combinations
The design loads shall be the minimum service loads and their combinations as stipulated in Chapter 2, Loads.
#### 10.7.2.5 Design for Serviceability
The whole structure and the individual members, connections and connectors shall be checked for serviceability according to the requirements of Sec 10.10.
### 10.7.3 Local Buckling
#### 10.7.3.1 Classification of Steel Sections
Steel sections are classified as compact, noncompact and slender sections. For a section to be compact, its flanges shall be continuously connected to the web or webs and the width-thickness ratio of its compression elements shall not exceed the applicable limiting width-thickness ratios given in Table 6.10.1. Steel section that do not qualify as compact are classified as noncompact when the width-thickness ratios of one or more compression element do not exceed the values shown for noncompact in Table 6.10.1. If the width-thickness ratio of any compression element exceeds the value, the section is classified as a slender section.
a) For unstiffened elements which are supported along only one edge, parallel to the direction of the compression force, the width shall be taken in accordance with (i) through (iv) below.
**Table 6.10.1: Limiting Width-Thickness Ratios for Compression Elements**
| Description of Element | Width-Thickness Ratio | Limiting Width-Thickness Ratios | |
| :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :-------------------: | :-----------------------------: | :---------------------------: |
| | | Compact | Noncompact\(3)\ |
| Flanges of I-shaped rolled beams and channels in flexure\(1)\ | b/t | 170/√Fy | 250/√Fy |
| Flanges of I-shaped welded beams in flexure | b/t | 170/√Fy | 250/√(Fyf kc)\(5)\ |
| Outstanding legs of pairs of angles in continuous contact; angles or plates projecting from rolled beams or columns, stiffeners on plate girders | b/t | NA | 250/√Fy |
| Angles or plates projecting from girders, built-up columns or other compression members; compression flanges of plate girders | b/t | NA | 250/√(Fyf kc) |
| Stems of tees | d/t | NA | 333/√Fy |
| Unstiffened elements simply supported along one edge, such as legs of single angle strutslegs of double-angle struts with separators and cross or star-shaped cross-sections | b/t | NA | 200/√Fy |
| Flanges of square and rectangular box and hollow structural sections of uniform thickness subject to bending or compression\<(2)\<; flange cover plates and diaphragm plates between lines of fasteners or welds | b/t | 500/√Fy | 625/√Fy |
| Unsupported width of cover plates perforated with a succession of access holes\<(4)\< | b/t | NA | 832/√Fy |
| All other uniformly compressed stiffened elements, i.e. supported along two edges | b/t, h/tw | NA | 665/√Fy |
| | d/t | 1680/√Fy | - |
| Webs in flexural compression\<(1)\< | h/tw | - | 1995/√Fb |
| | | | for fa/Fy \< 0.16 |
| Webs in combined flexural and axial compression | d/tw | | 1680/√Fy \[1-3.74(fa/Fy)] |
| | | | for fa/Fy > 0.16 |
| | | | 675/√Fy |
| | h/tw | | 1995/√Fb |
| Circular hollow sections | | | |
| In axial compression | D/t | 22752/Fy | - |
| In flexure | | 22752/Fy | - |
| | | | |
| **Notes:** (1) For hybrid beams, use the yield strength of the flange, Fyf instead of Fy | | | |
| (2) Assumes net area of plate at widest hole | | | |
| (3) For design of slender sections that exceed the noncompact limits see Sec 10.7.5.7. | | | |
| (4) See also Sec 10.7.6.5(a) | | | |
| (5) kc = 4.05/(h/t)^0.46 if h/t > 70, otherwise kc = 1.0 | | | |
For stiffened elements, i.e. supported along two edges parallel to the direction of the compression force, the width shall be taken as follows:
i) Clear distance h between flanges for web of rolled, built-up or formed sections.
ii) Full nominal depth d for webs of rolled, built-up or formed sections.
iii) Distance between adjacent lines of fasteners or lines of welds (b) for flange or diaphragm plates in built-up sections.
iv) Clear distance between webs less the inside corner radius on each side for flanges of rectangular hollow structural sections. If the corner radius is not known, the flat width may be taken as the total section width minus three times the thickness.
For tapered flanges of rolled sections, the thickness is the nominal value half-way between the free edge and the corresponding face of the web.
### 10.7.4 Design of Tension Members
This section specifies the requirements for design of prismatic members subjected to axial tension due to static forces acting through the centroidal axis.
#### 10.7.4.1 Allowable Stress
The allowable tensile stress of a member, except eyebars, shall not be greater than
Ft = 0.6Fy on the gross area
Ft = 0.5Fu on the effective net area
#### 10.7.4.2 Built-up Members
The longitudinal spacing of connectors between elements in continuous contact consisting of a plate and a shape or two plates shall not exceed the following :
a) 24 times the thickness of the thinner plate, nor 300 mm for painted members or unpainted members not subject to corrosion.
b) 14 times the thickness of the thinner plate, nor 175 mm for unpainted members of weathering steel subject to atmospheric corrosion.
In a tension member the longitudinal spacing of fasteners and intermittent welds connecting two or more shapes in contact shall not exceed 600 mm. Tension members composed of two or more shapes or plates separated by intermittent fillers shall be connected to one another at these fillers at intervals such that the slenderness ratio of either component between the fasteners does not exceed 300.
Either perforated cover plates or tie plates without lacing are permitted on the open sides of built-up tension members. The length of tie plates shall not be less than ⅔ of the distance between the lines of welds or fasteners connecting them to the components of the member. The thickness of such tie plates shall not be less than 1/6 of the distance between these lines. The longitudinal spacing of intermittent welds or fasteners at the plates shall not exceed 150 mm.
The spacing of the plates shall be such that the slenderness ratio of any component in the length between the plates shall not be greater than 300.
#### 10.7.4.3 Pin Connected Members
#### c) Eyebars
Eyebars shall be of uniform thickness, without reinforcement at the pin holes, and have circular heads whose periphery is connected with the pin hole. The radius of the transition between the circular head and the eyebar body shall be at least equal to the diameter of the head.
For calculation purposes, the width of the body of an eyebar shall not be greater than 8 times its thickness.
The thickness may be less than 12 mm provided external nuts are used to tighten pin plates and filler plates into snug contact. For calculation purposes, the distance from the hole edge to plate edge perpendicular to the direction of the applied load shall not be less than ½ nor greater than ¾ times the width of the eyebar body.
The pin diameter shall be at least ⅞ times the eyebar width.
The pin hole diameter shall not be more than 0.08 mm greater than the diameter of the pin.
For steel having a yield stress greater than 480 N/mm² the hole diameter shall not be greater than 5 times the plate thickness and the width of the eyebar shall be reduced accordingly.
### 10.7.5 DESIGN OF COLUMNS AND OTHER COMPRESSION MEMBERS
These provisions cover the design of compact and noncompact sections subjected to axial compression through the centroidal axis. The provisions also cover the design of members with slender elements, tapered members and members subjected to combined axial compression and flexure.
#### 10.7.5.1 Effective Length and Slenderness Ratio
The effective length factor K shall be determined in accordance with Sec 10.5.2.
In determining the slenderness ratio of an axially loaded compression member, the length shall be taken as its effective length Kl and r as the corresponding radius of gyration. For limiting slenderness ratio see Sec 10.6.5.
#### 10.7.5.2 Allowable Stress
On the gross section of axially loaded compression members whose cross-sections satisfy the requirements of Table 6.10.1, when Kl/r, the largest effective slenderness ratio of any unbraced segment is less than Cc, the allowable stress is:
$$
F_a = \left[1 - \frac{(Kl/r)^2}{2C_c^2}\right] F_y / \left[\frac{5}{3} + \frac{3(Kl/r)}{8C_c} - \frac{(Kl/r)^3}{8C_c^3}\right] \tag{10.7.1}
$$
where
$$
C_c = \sqrt{\frac{2\pi^2 E}{F_y}}
$$
On the gross section of axially loaded compression members, when Kl/r exceeds Cc, the allowable stress is:
$$
F_a = \frac{12\pi^2 E}{23(Kl/r)^2} \tag{10.7.2}
$$
#### 10.7.5.3 Flexural-Torsional Buckling
Singly symmetric and unsymmetric columns, such as angles or tee-shaped columns, and doubly symmetric columns such as cruciform or built-up columns with very thin walls, may require consideration of flexural-torsional and torsional buckling.
#### 10.7.5.4 Built-up Members
All parts of built-up compression members and the transverse spacing of their lines of fasteners shall satisfy the requirements of Sec 10.6.5.
Spacing and edge distance requirements for weathering steel members shall satisfy the requirements of Sec 10.9.3.10.
At the ends of built-up compression members bearing on base plates or milled surfaces, all components in contact with one another shall be connected by rivets or bolts spaced longitudinally not more than 4 diameters apart for a distance equal to 1½ times the maximum width of the member, or by continuous welds having a length not less than the maximum width of the member.
The maximum longitudinal spacing of bolts, rivets or intermittent welds connecting two rolled shapes in contact shall not be greater than 600 mm. In addition, for painted members and unpainted members not subject to corrosion where the outside component consists of a plate, the maximum longitudinal spacing shall not exceed:
a) $333/\sqrt{F_y}$ times the thickness of the outside plate nor 300 mm when fasteners are not staggered along adjacent gauge lines.
b) $500/\sqrt{F_y}$ times the thickness of the outside plate nor 450 mm when fasteners are staggered along adjacent gauge lines.
Compression members composed of two or more rolled shapes separated by intermittent fillers shall be connected at these fillers at intervals such that the slenderness ratio Kl/r of either shape, between the fasteners, does not exceed ¾ times the governing slenderness ratio of the built-up member. The least radius of gyration r shall be used in computing the slenderness ratio of each component part. At least two intermediate connectors shall be used along the length of the built-up member. All connections, including those at the ends, shall be welded or shall utilize high strength bolts tightened to the requirements of Table 6.10.12.
Open sides of compression members built up from plates or shapes shall be provided with lacing or tie plates at each end and at intermediate points if the lacing is interrupted. Tie plates shall be as near the ends as practicable. In main members carrying calculated stress, the end tie plates shall have a length of not less than the distance between the lines of fasteners or welds connecting them to the components of the member. Intermediate tie plates shall have a length not less than half of this distance. The thickness of the plates shall not be less than ⅜ of the distance between the lines of fasteners or welds connecting them to the components of the member. In bolted and riveted construction, the spacing in the direction of stress in tie plates shall not be more than 6 diameters and the tie plates shall be connected to each component by at least 3 fasteners. In welded construction, the welding on each line connecting a tie plate shall aggregate not less than ⅜ of the length of the plate.
Lacing, including flat bars, angles, channels or other shapes employed as lacing, shall be so spaced that the ratio l/r of the flange included between their connections shall not exceed ¾ times the governing ratio for the member as a whole. Lacing shall be proportioned to resist a shearing stress normal to the axis of the member equal to 2% of the total compressive stress in the member. The ratio l/r for lacing bars arranged in single systems shall not exceed 140. For double lacing this ratio shall not exceed 200. Double lacing bars shall be joined at their intersections. For lacing bars in compression the unsupported length of the lacing bar shall be taken as the distance between fasteners or welds connecting it to the components of the built-up member for single lacing, and 70% of that distance for double lacing. The inclination of lacing bars to the axis of the member shall preferably be not less than 60° for single lacing and 45° for double lacing. When the distance between the lines of fasteners or welds in the flanges is more than 375 mm, the lacing shall preferably be double or be made of angles.
The function of the tie plates and lacing may be performed by continuous cover plates perforated with access holes. The unsupported width of such plates at access holes, as defined in Sec 10.7.3, is assumed available to resist axial stresses, provided that:
a) The width to thickness ratio conforms to the limitations of Sec 10.7.3;
b) The ratio of length (in direction of stress) to width of holes shall not exceed 2;
c) The clear distance between holes in the direction of stress shall be not less than the transverse distance between nearest lines of connecting fasteners or welds; and
d) The periphery of the holes at all points shall have a minimum radius of 40 mm.
#### 10.7.5.5 Pin Connected Compression Member
Pin connections of pin connected compression members shall conform to the requirements of Sec 10.7.4.3.
#### 10.7.5.6 Column Web Shear
Column connections shall be investigated for concentrated force introduction in accordance with Sec 10.7.11.1.
#### 10.7.5.7 Slender Compression Elements
#### a) Unstiffened Compression Elements
The allowable stress of unstiffened compression elements whose width-thickness ratio exceeds the applicable noncompact value as specified in Sec 10.7.3.1 shall be subject to a reduction factor Qs. The value of Qs shall be determined by Eq (10.7.3) through (10.7.8), as applicable, where b is the width of the unstiffened element as defined in Sec 10.7.3.1. When such elements comprise the compression flange of a flexural member, the maximum allowable bending stress shall not exceed 0.60 FyQs nor the applicable value as provided in Sec 10.7.6.3(c). The allowable stress of axially loaded compression members shall be modified by the appropriate reduction factor Qs as provided in (c) below.
For Single Angles:
When $200/\sqrt{F_y} < b/t < 407/\sqrt{F_y}$
$$
Q_s = 1.340 - 0.0017(b/t)\sqrt{F_y} \tag{10.7.3}
$$
When $b/t \geq 407/\sqrt{F_y}$
$$
Q_s = \frac{106867}{F_y(b/t)^2} \tag{10.7.4}
$$
For angles or plates projecting from columns or other compression members, and for projecting elements of compression flanges of beams and girders:
When $250/\sqrt{F_y/k_c} < b/t < 512/\sqrt{F_y/k_c}$
$$
Q_s = 1.293 - 0.0012(b/t)\sqrt{F_y/k_c} \tag{10.7.5}
$$
When $b/t > 512/\sqrt{F_y/k_c}$
$$
Q_s = \frac{180640 k_c}{F_y(b/t)^2} \tag{10.7.6}
$$
where
$$
k_c = \frac{4.05}{(h/t)^{0.46}} \text{ if } h/t > 70, \text{ otherwise } k_c = 1.0
$$
For stems of tees:
When $333/\sqrt{F_y} < b/t < 462/\sqrt{F_y}$
$$
Q_s = 1.908 - 0.0027(b/t)\sqrt{F_y} \tag{10.7.7}
$$
When $b/t \geq 462/\sqrt{F_y}$
$$
Q_s = \frac{137890}{F_y(b/t)^2} \tag{10.7.8}
$$
Unstiffened elements of tees whose proportions exceed the limits of Sec 10.7.3.1 shall conform to the limits given in Table 6.10.2.
**Table 6.10.2: Limiting Proportions for Channels and Tees**
| Shape | Ratio of Full Flange Width to Profile Depth | Ratio of Flange Thickness to Web or Stem Thickness |
| :----------------- | :-----------------------------------------: | :------------------------------------------------: |
| Built-up or rolled | ≤0.25 | ≤3.0 |
| Channels | ≤0.50 | ≤2.0 |
| Built-up tees | ≥0.50 | ≥1.25 |
| Rolled tees | ≥0.50 | ≥1.10 |
#### b) Stiffened Compression Elements
When the width-thickness ratio of uniformly compressed stiffened elements (except perforated cover plates) exceeds the noncompact limit stipulated in Sec 10.7.3.1 reduced effective width be shall be used in computing the design properties of the section containing the element, except that the ratio be/t need not be taken as less than the applicable value permitted in Sec 10.7.3.1.
i) For the flanges of square and rectangular sections of uniform thickness:
$$
b_e = \frac{665}{\sqrt{f}} \left[1 - \frac{132}{(b/t)\sqrt{f}}\right] \leq b \tag{10.7.9}
$$
ii) For other uniformly compressed elements:
$$
b_e = \frac{665}{\sqrt{f}} \left[1 - \frac{116}{(b/t)\sqrt{f}}\right] \leq b \tag{10.7.10}
$$
Where
be = reduced width, mm
f = computed compressive stress (axial plus bending stresses) in the stiffened elements, based on the design properties as specified herein, N/mm². If unstiffened elements are included in the total cross section, f for the stiffened element must be such that the maximum compressive stress in the unstiffened element does not exceed FyQs or FyQa, as applicable.
When the allowable stresses are increased due to wind or seismic loading in accordance with the provisions of Sec 10.7.2.2 the effective width be shall be determined on the basis of 0.75 times the stress caused by wind or seismic loading acting alone or in combination with the design dead and live loading.
iii) For axially loaded circular sections:
Members with diameter to thickness ratios D/t greater than 22752/Fy, but having a diameter to thickness ratio of less than 89630/Fy, shall not exceed the smaller value determined by Sec 10.7.5.2 nor
$$
F_a = \frac{4564}{D/t} + 0.40F_y \tag{10.7.11}
$$
#### c) Design Properties
Properties of sections shall be determined using the full cross-section, except as follows:
In computing the moment of inertia and section modulus of flexural members, the effective width of uniformly compressed stiffened elements, as determined in (b) above, shall be used in determining effective cross-sectional properties.
For stiffened elements of the cross-section
$$
Q_a = \frac{\text{effective area}}{\text{actual area}} \tag{10.7.12}
$$
For unstiffened elements of the cross-section, Qs is to be determined according to (a) above.
For axially loaded compression members the gross cross-sectional area and the radius of gyration r shall be computed on the basis of the actual cross-section.
The allowable stress for axially loaded compression members containing unstiffened or stiffened elements shall not exceed
$$
F_a = \frac{\left[1 - \frac{(Kl/r)^2}{2C_c^2}\right] F_y}{\frac{5}{3} + \frac{3(Kl/r)}{8C_c} - \frac{(Kl/r)^3}{8C_c^3}} \tag{10.7.13}
$$
when Kl/r is less than $C_c'$, where
$$
C_c' = \sqrt{\frac{2\pi^2 E}{QF_y}} \tag{10.7.14}
$$
and Q is to be determined as follows:
i) Cross-sections composed entirely of unstiffened elements, Q = Qs
ii) Cross-sections composed entirely of stiffened elements, Q = Qa
iii) Cross-sections composed of both stiffened and unstiffened elements, Q = QsQa
When Kl/r exceeds $C_c'$:
$$
F_a = \frac{12\pi^2 E}{23(Kl/r)^2} \tag{10.7.15}
$$
#### d) Combined Axial and Flexural Stress
In applying the provisions of Sec 10.7.8 to members subject to combined axial and flexural stress and containing stiffened elements whose width-thickness ratio exceeds the applicable noncompact limit given in Sec 10.7.3.1, the stresses Fy, fy and fjy shall be calculated on the basis of the section properties as provided in (c) above, as applicable. The allowable bending stress Fb for members containing unstiffened elements whose width-thickness ratio exceeds the noncompact limit given in Sec 10.7.3.1 shall be the smaller of 0.60FyQs or the value provided in Sec 10.7.6.3(c). The term fy/0.60Fy in Eq (10.7.59) and (10.7.48) shall be replaced by fy/0.60FyQs.
### 10.7.6 DESIGN OF BEAMS AND OTHER FLEXURAL MEMBERS
This section covers the design of singly or doubly symmetric beams including hybrid beams and girders loaded in the plane of symmetry. It also applies to channels loaded in a plane passing through the shear centre parallel to the web or restrained against twisting at load points and points of support.
#### 10.7.6.1 Proportioning of Beams and Girders
Rolled or welded shapes, plate girders and cover plated beams shall be proportioned by the moment of inertia of the gross section. No reduction shall be made for shop or field bolt or rivet holes in either flange provided that
$$
0.5F_t A_{fn} \geq 0.6F_y A_{fg} \tag{10.7.16}
$$
where Afg and Afn are calculated in accordance with the provisions of Sec 10.6.1 and 10.6.2.
When
$$
0.5F_t A_{fn} < 0.6F_y A_{fg} \tag{10.7.17}
$$
the member flexural properties shall be based on an effective tension flange area Afe, where
$$
A_{fe} = 0.833\frac{F_u}{F_y} A_{fn} \tag{10.7.18}
$$
Hybrid girders may be proportioned by the moment of inertia of their gross section, subject to the applicable provisions in Sec 10.7.7.1, provided they are not required to resist an axial force greater than 0.15Fy times the area of the gross section, where Fy is the yield stress of the flange material. For hybrid girders, the flanges at any given section shall have the same cross-sectional area and be of the same grade of steel.
Flanges of welded beams or girders may be varied in thickness or width by splicing a series of plates or by the use of cover plates.
The total cross-sectional area of cover plates of bolted or riveted girders shall not exceed 70% of the total flange area.
High strength bolts, rivets or welds connecting flange to web, or cover plate to flange shall be designed to resist the total horizontal shear resulting from the bending forces on the girder. The longitudinal distribution of these bolts, rivets or intermittent welds shall be in proportion to the intensity of the shear. However, the longitudinal spacing of the connector shall not exceed the maximum spacing permitted for tension or compression members in Sec 10.7.4.2 or 10.7.5.4 respectively. Bolts, rivets or welds connecting flange to web shall also be designed to transmit to the web any loads applied directly to the flange, unless provision is made to transmit such loads by direct bearing.
Partial length cover plates shall be extended beyond the theoretical cut-off point and the extended portion shall be attached to the beam or girder by high strength bolts in a slip critical connection or by rivets or fillet welds. The connection shall be adequate to develop the cover plate's portion of the flexural stresses in the beam or girder at the theoretical cut-off point within the applicable allowable stresses specified in Sec 10.9.2.4 and 10.9.3.4 to develop the cover plates portion of the flexural stresses in the beam or girder at the theoretical cutoff point.
In addition, for welded cover plates, the welds connecting the cover plate termination to the beam or girder in the length a' defined below, shall be adequate at the allowable stresses, to develop the cover plate's portion of the flexural stresses in the beam or girder at the distance a' from the end of the cover plate. The length a', measured from the end of the cover plate, shall be:
a) A distance equal to the width of the cover plate when there is a continuous weld equal to or larger than ⅔ of the plate thickness across the end of the plate and continuous welds along both edges of the cover plate in the length a'.
b) A distance equal to 1½ times the width of the cover plate when there is a continuous weld smaller than ⅔ of the plate thickness across the end of the plate in the length a'.
c) A distance equal to 2 times the width of the cover plate when there is no weld across the end of the plate, but continuous welds along both edges of the cover plate in the length a'.
#### 10.7.6.2 Proportioning of Crane Girders
In addition to satisfying the provisions of Sec 10.7.6.1 the flanges of beams or girders supporting cranes or other moving loads shall be proportioned to resist the horizontal forces produced by such loads, as specified in Sec 2.3.8 of Chapter 2, Loads.
#### 10.7.6.3 Allowable Stresses - Strong Axis Bending of I-shaped Members and Channels
#### a) Members with Compact Sections
For compact symmetrical sections loaded in the plane of their minor axis, the allowable stress is
$$
F_b = 0.66F_y \tag{10.7.19}
$$
provided the flanges are connected continuously to the web or webs and the laterally unsupported length of the compression flanges Lb shall not exceed the value of Lc as given by the smaller of the following:
$$
\frac{200b_f}{\sqrt{F_y}} \text{ or } \frac{138000}{(d/A_f)\sqrt{F_y}} \tag{10.7.20}
$$
Members (including composite members and excluding hybrid members and members with yield points greater than 445 N/mm²) which meet the requirements for compact sections and are continuous over supports or rigidly framed to columns may be proportioned for ⅑ of the negative moments produced by gravity loading when such moments are maximum at points of support, provided that, for such members, the maximum positive moment is increased by ⅑ of the average negative moments. This reduction shall not apply to moments produced by loading on cantilevers. If the negative moment is resisted by a column rigidly framed to the beam or girder, the ⅑ reduction is permitted in proportioning the column for the combined axial and bending loading, provided that the stress fa due to any concurrent axial load on the member does not exceed 0.15Fy.
#### b) Members with Noncompact Sections
For members satisfying the requirement of (a) above except that their flanges are noncompact (excluding built-up members and members with yield points greater than 445 N/mm²), the allowable stress is
$$
F_b = F_y \left[0.79 - 0.00038\frac{b_f}{t_f}\sqrt{F_y}\right] \tag{10.7.21}
$$
For built-up members satisfying the requirements of (a) above except that their flanges are noncompact and their webs are compact or noncompact, (excluding hybrid girders and members with yield points greater than 445 N/mm²) the allowable stress is
$$
F_b = F_y \left[0.79 - 0.00038\frac{b_f}{t_f}\sqrt{\frac{F_y}{k_c}}\right] \tag{10.7.22}
$$
where
$$
k_c = \frac{4.05}{(h/t_w)^{0.46}} \text{ if } h/t_w > 70, \text{ otherwise } k_c = 1.0
$$
For members with a noncompact section but not included above, and loaded through the shear centre and braced laterally in the region of compression stress at intervals not exceeding $\frac{200b_f}{\sqrt{F_y}}$ the allowable stress is
$$
F_b = 0.60F_y \tag{10.7.23}
$$
#### c) Members with Compact or Noncompact Sections with Unbraced Length Greater Than Lc
For flexural members with compact or noncompact sections and with unbraced lengths greater than Lc as defined in (a) above the allowable bending stress in tension is determined from Eq (10.7.23).
For such members with an axis of symmetry in, and loaded in the plane of their web, the allowable bending stress in compression is determined as the larger value from Eq (10.7.24) or (10.7.25) and (10.7.26) except that Eq (10.7.26) is applicable only to sections with a compression flange that is solid and approximately rectangular in cross-section and that has an area not less than the tension flange. Higher values of the allowable compressive stress are permitted if justified by a more precise analysis. Stresses shall not exceed those permitted by Sec 10.7.7 if applicable.
For channels bent about their major axes, the allowable compressive stress is determined from Eq (10.7.26).
When
$$
\sqrt{\frac{703 \times 10^3 C_b}{F_y}} \leq \frac{l}{r_T} \leq \sqrt{\frac{3516 \times 10^3 C_b}{F_y}}
$$
$$
F_b = \left[\frac{2}{3} - \frac{F_y(l/r_T)^2}{10550 \times 10^3 C_b}\right] F_y \leq 0.60F_y \tag{10.7.24}
$$
When
$$
\frac{l}{r_T} > \sqrt{\frac{3516 \times 10^3 C_b}{F_y}}
$$
$$
F_b = \frac{1172 \times 10^3 C_b}{(l/r_T)^2} \leq 0.60F_y \tag{10.7.25}
$$
For any value of l/rT:
$$
F_b = \frac{83 \times 10^3 C_b}{(ld/A_f)} \leq 0.60F_y \tag{10.7.26}
$$
where
$l$ = distance between cross-sections braced against twist or lateral displacement of the compression flange, mm. For cantilevers braced against twist only at the support, $l$ may conservatively be taken as the actual length.
$C_b$ = $1.75+1.05(M_1/M_2)+0.3(M_1/M_2)^2$, but not more than 2.3, where $M_1$ is the smaller and $M_2$ the larger bending moment at the ends of the unbraced length, taken about the strong axis of the member, and where $M_1/M_2$, the ratio of end moments, is positive when $M_1$ and $M_2$ have the same sign (reverse curvature bending) and negative when they are of opposite signs (single curvature bending). When the bending moment at any point within an unbraced length is larger than that at both ends of this length, the value of $C_b$ shall be taken as unity. When computing $C_b$, to be used in Eq (10.7.58), $C_b$ may be computed by the equation given above for frames subject to joint translation. $C_b$ shall be taken as unity for frames braced against joint translation. $C_b$ may conservatively be taken as unity for cantilever beams.
For hybrid plate girders, $F_y$ in Eq (10.7.26) shall not apply to hybrid girders.
The provisions of this section do not apply to T-sections if the stem is in compression anywhere along the unbraced length.
#### 10.7.6.4 Allowable Stress : Weak Axis Bending of I-Shaped Members, Solid Bars and Rectangular Plates
Lateral bracing is not required for members loaded through the shear centre about their weak axis, nor for members of equal strength about both axes.
a) Members with Compact Sections : For doubly symmetrical I- and H-shaped members with compact flanges continuously connected to the web and bent about their weak axes (except members with yield points greater than 445 N/mm²), solid round and square bars, and solid rectangular sections bent about their weaker axes, the allowable stress is
$$
F_b = 0.75 F_y
$$
(10.7.27)
b) Members with Noncompact Sections : For members not meeting the requirements for compact sections and not covered in Sec 10.7.6.5, bent about their minor axis, the allowable stress is
$$
F_b = 0.60 F_y
$$
(10.7.28)
Doubly symmetrical I- and H-shape members bent about their weak axes (except members with yield points greater than 445 N/mm²) with noncompact flanges continuously connected to the web may be designed on the basis of an allowable stress of
$$
F_b = F_y \left[ 1.075 - 0.00095 \left( \frac{b_f}{t_f} \right) \sqrt{F_y} \right]
$$
(10.7.29)
#### 10.7.6.5 Allowable Stress : Bending of Box Members, Circular and Rectangular Tubes
a) Members with Compact Sections : For members bent about their strong or weak axes, members with compact sections and flanges continuously connected to the webs, the allowable stress is
$$
F_b = 0.66 F_y
$$
(10.7.30)
To be classified as a compact section, a box-shaped member shall have, in addition to the requirements of Sec 10.7.3, a depth not greater than 6 times the width, a flange thickness not greater than 2 times the web thickness and a laterally unsupported length $L_b$ less than or equal to $L_c$ given by Eq (10.7.31).
$$
L_c = \left( 13445 + 8274 \frac{M_1}{M_2} \right) \frac{b}{F_y}
$$
(10.7.31)
However, $L_b$ need not be less than 8274 (b/Fy), where $M_1$ is the smaller and $M_2$ the larger bending moment at the ends of the unbraced length, taken about the strong axis of the member, and where $M_1/M_2$, the ratio of moments is positive when $M_1$ and $M_2$ have the same sign (reverse curvature bending) and negative when they are of opposite signs (single curvature bending).
b) Members with Noncompact Sections : For box-type and tubular flexural members that meet the noncompact section requirements, the allowable stress is
#### 10.7.6.6 Allowable Shear Stresses
For $h/t_w ≤ 1000/ \sqrt{F_y}$, on the overall depth times the web thickness, the allowable shear stress is :
$$
F_s = 0.40F_y
$$
(10.7.33)
For $h/t_w > 1000/ \sqrt{F_y}$, the allowable shear stress on an area obtained by multiplying the clear distance between the flanges by the web thickness is
$$
F_s = 0.346C_v F_y ≤ 0.40F_y
$$
(10.7.34)
where
$$
C_v = \frac{310260k_v}{F_y(h/t_w)^2} \text{ when } C_v \text{ is less than } 0.8
$$
$$
= \frac{500}{h/t_w} \sqrt{\frac{k_v}{F_y}} \text{ when } C_v \text{ is more than } 0.8
$$
$$
k_v = 4.00 + \frac{5.34}{(a/h)^2} \text{ when } a/h \text{ is less than } 1.0
$$
$$
= 5.34 + \frac{4.00}{(a/h)^2} \text{ when } a/h \text{ is more than } 1.0
$$
For shear rupture on coped beam end connections see Sec 10.9.4.1.
Maximum h/tₘ limits are given in Sec 10.7.7.
An alternative design method for plate girders utilizing tension field action is given in Sec 10.7.7.
#### 10.7.6.7 Transverse Stiffeners
Intermediate stiffeners are required when the ratio h/tₘ is greater than 260 and the maximum web shear stress fₛ is greater than that permitted by Eq (10.7.34).
The spacing of intermediate stiffeners, when required, shall be such that the web shear stress will not exceed the value for Fₛ given by Eq (10.7.34) or (10.7.53), as applicable, and
$$
\frac{a}{h} ≤ \left[ \frac{260}{h/t_w} \right]^2
$$
(10.7.35)
The spacing of intermediate stiffeners shall, however, not be more than 3h.
#### 10.7.6.8 Built-up Members
Where two or more rolled beams or channels are used side by side to form a flexural member, they shall be connected together at intervals of not more than 1500 mm. Through-bolts and separators are permitted, provided that, in beams having a depth of 300 mm or more, not less than 2 bolts shall be used at each separator location. When concentrated loads are carried from one beam to the other, or distributed between the beams, diaphragms having sufficient stiffness to distribute the load shall be riveted, bolted or welded between the beams.
#### 10.7.6.9 Web-tapered Members
a) General Requirements : The design of tapered members shall meet the following special requirements along with the requirements of Sec 10.7.6.3 through 10.7.6.8.
i) It shall possess at least one axis of symmetry which shall be perpendicular to the plane of bending if moments are present.
ii) The flanges shall be of equal and constant area.
iii) The depth shall vary linearly as
$$
d = d_o \left( 1 + \gamma \frac{z}{L} \right)
$$
(10.7.36)
where
$$
\gamma = (d_L - d_o)/d_o ≤ \text{ the smaller of } 0.268 \text{ (} L/d_o \text{) or } 6.0
$$
b) Allowable Tensile Stress : The allowable tensile stress of tapered tension members shall be determined in accordance with Sec 10.7.4.1.
c) Allowable Compressive Stress : On the gross section of axially loaded tapered compression members, the allowable compressive stress in N/mm² shall not exceed the following:
When the effective slenderness ratio S is less than Cₑ :
$$
F_{cr} = \frac{\left(1.0 - \frac{S^2}{2C_c^2}\right) F_y}{\frac{5}{3} - \frac{3S}{8C_c} - \frac{S^3}{8C_c^3}}
$$
(10.7.37)
When the effective slenderness ratio S exceeds Cₑ :
$$
F_{cr} = \frac{12 π^2 E}{23S^2}
$$
(10.7.38)
where
* $S$ = $Kl/r_{eg}$ for weak axis bending and $K_y l/r_{eg}$ for strong axis bending
* $K_y$ = effective length factor for a tapered member as determined by an analysis following reliable references
d) Allowable Flexural Stress : Tension and compression stresses on extreme fibres of tapered flexural members, in N/mm², shall not exceed the following values :
$$
F_{by} = \frac{2}{3} \left[ 1.0 - \frac{F_y}{6B_e} \sqrt{F_{sy}^2 + F_{wy}^2} \right] F_y ≤ 0.60F_y
$$
(10.7.39)
unless $F_{by} ≤ F_y / 3$ in which case
$$
F_{by} = B_y \sqrt{F_{sy}^2 + F_{wy}^2}
$$
(10.7.40)
In the above equations,
$$
F_{sy} = \frac{2.1 \times 10^6}{h_s L_{d_s}/A_f}
$$
(10.7.41)
$$
F_{wy} = \frac{756 \times 10^6}{(h_w L_f/r_w)^2}
$$
(10.7.42)
where
$$
h_w = \text{factor equal to } 1.0 + 0.023 \gamma \sqrt{L_{d_s}/A_f}
$$
and B is determined as follows :
i) When the maximum moment $M_2$ in three adjacent segments of approximately equal unbraced length is located within the central segment and $M_1$ is the larger moment at one end of the three-segment portion of a member:
$$
B = 1.0 + 0.37 \left(1.0 + \frac{M_1}{M_2}\right) + 0.50\gamma \left(1.0 + \frac{M_1}{M_2}\right) ≥ 1.0
$$
(10.7.43)
ii) When the largest computed bending stress fb2 occurs at the larger of two adjacent segments of approximately equal unbraced lengths and fb1 is the computed bending stress at the smaller end of the two-segment portion of a member :
$$
B = 1.0 + 0.58 \left(1 + \frac{f_{b1}}{f_{b2}}\right) - 0.707\left(1 + \frac{f_{b1}}{f_{b2}}\right) ≥ 1
$$
(10.7.44)
iii) When the largest computed bending stress fb2 occurs at the smaller end of two adjacent segments of approximately equal unbraced length and fb1 is the computed bending stress at the larger end of the two-segment portion of a member :
$$
B = 1.0 + 0.55 \left(1.0 + \frac{f_{b1}}{f_{b2}}\right) + 2.20\gamma \left(1.0 + \frac{f_{b1}}{f_{b2}}\right) ≥ 1.0
$$
(10.7.45)
In the foregoing, $γ = (d_L - d_o)/d_o$ is calculated for the unbraced length containing the maximum computed bending stress.
iv) When the computed bending stress at the smaller end of a tapered member or segment thereof is equal to zero:
$$
B = \frac{1.75}{1.0 + 0.25\sqrt{\gamma}}
$$
(10.7.46)
where $γ = (d_L - d_o)/d_o$, calculated for the unbraced length adjacent to the point of zero bending stress.
e) Allowable Shear : The allowable shear stress of tapered flexural members shall be in accordance with Sec 10.7.6.6.
f) Combined Flexure and Axial Force : Tapered members and unbraced segments thereof subject to both axial compression and bending stresses shall be proportioned to satisfy the following requirement:
$$
\left(\frac{f_{ao}}{F_{ay}}\right) + \frac{C'_{m}}{1 - \frac{f_{a0}}{F'_{ey}}} \left(\frac{f_b}{F_{by}}\right) ≤ 1.0
$$
(10.7.47)
and
$$
\frac{f_a}{0.60F_y} + \frac{f_b}{F_{by}} ≤ 1.0
$$
(10.7.48)
When $\frac{f_{ao}}{F_{ay}} ≤ 0.15$, Eq (10.7.49) is permitted in lieu of Eq (10.7.47) and (10.7.48).
$$
\left(\frac{f_{ao}}{F_{ay}}\right) + \left(\frac{f_b}{F_{by}}\right) ≤ 1.0
$$
(10.7.49)
### 10.7.7 Design of Plate Girders
Plate girders shall be distinguished from beams on the basis of the web slenderness ratio h/tₘ. When this value is greater than $1995/ \sqrt{F_b}$, the provisions of this section shall apply for allowable bending stress, otherwise Sec 10.7.6 shall be applicable.
For allowable shear stress and transverse stiffener design, the provisions of Sec 10.7.6.6 and 10.7.6.7 shall apply, unless tension field action is utilized, in which case Sec 10.7.7.3 and 10.7.7.4 shall be applicable.
#### 10.7.7.1 Web Slenderness Limitations
When no transverse stiffeners are provided or when transverse stiffeners are spaced more than 1½ times the distance between flanges
$$
\frac{h}{t_w} ≤ \frac{96550}{\sqrt{F_{yf}(F_{yf} + 114)}}
$$
(10.7.50)
When transverse stiffeners are provided, spaced not more than 1½ times the distance between flanges
$$
\frac{h}{t_w} ≤ \frac{5250}{\sqrt{F_yf}}
$$
(10.7.51)
#### 10.7.7.2 Allowable Bending Stress
When the web depth to thickness ratio exceeds $1995/ \sqrt{F_b}$, the maximum bending stress in the compression flange shall not exceed
$$
F'_b ≤ F_b R_{PG} R_e
$$
(10.7.52)
where
$F_b$ = applicable bending stress given in Sec 10.7.6, N/mm²
and
$$
R_{PG} = 1 - 0.0005 \frac{A_w}{A_f} \left(\frac{h}{t} \frac{1995}{\sqrt{F_b}}\right) ≤ 1.0
$$
$$
R_e = \frac{12 + \left(\frac{A_w}{A_f}\right)(3α - α^2)}{12 + 2\left(\frac{A_w}{A_f}\right)} ≤ 1.0
$$
$α = 0.6 F_{yw}/F_b ≤ 1.0$
For nonhybrid girders, $R_e$ shall be taken as 1.0.
#### 10.7.7.3 Allowable Shear Stress with Tension Field Action
Except as herein provided, the largest average web shear, fᵥ, N/mm² computed for any condition of complete or partial loading, shall not exceed the value given by Eq (10.7.34).
Alternatively, for girders other than hybrid girders, if intermediate stiffeners are provided and spaced to satisfy the provisions of Sec 10.7.7.4 and if Cₛ ≤ 1, the allowable shear including tension field action given by Eq (10.7.53) is permitted in lieu of the value given by Eq (10.7.34).
$$
F_b = 0.346F_y \left[ C_v + \frac{1 - C_v}{1.15\sqrt{1 + (a/h)^2}} \right] ≤ 0.40F_y
$$
(10.7.53)
#### 10.7.7.4 Transverse Stiffeners
Transverse stiffeners shall meet the requirements of Sec 10.7.6.7.
In girders designed on the basis of tension field action, the spacing between stiffeners at end panels, at panels containing large holes, and at panels adjacent to panels containing large holes shall be such that fᵥ does not exceed the value given by Eq (10.7.34).
Bolts and rivets connecting stiffeners to the girder web shall be spaced not more than 300 mm on centres. If intermittent fillet welds are used, the clear distance between welds shall not be more than 16 times the web thickness nor more than 250 mm.
The moment of inertia, Iₛₜ of a pair of intermediate stiffeners, or a single intermediate stiffener, with reference to an axis in the web centre line of the web shall be limited as follows
$$
I_{st} ≥ \left(\frac{h}{50}\right)^4
$$
(10.7.54)
The gross area (total area, when stiffeners are furnished in pairs), in mm², of intermediate stiffeners spaced as required for Eq (10.7.53) shall be not less than
$$
A_{st} = \frac{1 - C_v}{2} \left[\frac{a}{h} - (a/h)^2\right] \sqrt{1 + (a/h)^2} \text{YDH}
$$
(10.7.55)
where
* $D$ = 1.0 for stiffeners furnished in pairs
* $D$ = 1.8 for single angle stiffeners
* $D$ = 2.4 for single plate stiffeners
When the greatest shear stress fᵥ in a panel is less than that permitted by Eq (10.7.53) the reduction of this gross area requirement is permitted in like proportion.
Intermediate stiffeners required by Eq (10.7.53) shall be connected for a total shear transfer, N per linear mm of single stiffener or pair of stiffeners, not less than
$$
f_{ws} = h_e \left(\frac{F_y}{647}\right)^3
$$
(10.7.56)
where Fy = yield stress of web steel.
This shear transfer may be reduced in the same proportion that the largest computed shear stress fₛ in the adjacent panels is less than that permitted by Eq (10.7.53). However, rivets and welds in intermediate stiffeners which are required to transmit the web an applied concentrated load or reaction shall be proportioned for not less than the applied load or reaction.
Intermediate stiffeners may be stopped short of the tension flange, provided bearing is not needed to transmit a concentrated load or reaction. The weld by which intermediate stiffeners are attached to the web shall be terminated not less than four times nor more than six times the web thickness from the nearest toe of the web to flange weld. When single stiffeners are used, they shall be attached to the compression flange, if it consists of a rectangular plate, to resist any uplift tendency due to torsion in the plate. When lateral bracing is attached to a stiffener, or a pair of stiffeners, in turn, these, in turn, shall be connected to the compression flange to transmit 1% of the total flange stress, unless the flange is composed only of angles.
### 10.7.8 Combined Stresses
The design of members subject to combined stresses shall be in accordance with this section.
This section deals with doubly and singly symmetrical members only. For determination of Fₐ see 10.7.5 and for determination of Fbx and Fby see Sec 10.7.6.
#### 10.7.8.1 Axial Compression and Bending
Members subjected to both axial compression and bending stresses shall be proportioned to satisfy the following requirements :
$$
\frac{f_a}{F_a} + \frac{C_{m} f_{bx}}{1 - \frac{f_a}{F'_{ex}}} + \frac{C_{my} f_{by}}{1 - \frac{f_a}{F'_{ey}}} ≤ 1.0
$$
(10.7.58)
$$
\frac{f_a}{0.60F_y} + \frac{f_{bx}}{F_{bx}} + \frac{f_{by}}{F_{by}} ≤ 1.0
$$
(10.7.59)
When fa/Fₐ ≤ 0.15, Eq (10.7.60) is permitted in lieu of Eq (10.7.58) and (10.7.59).
$$
\frac{f_a}{F_a} + \frac{f_{bx}}{F_{bx}} + \frac{f_{by}}{F_{by}} ≤ 1.0
$$
(10.7.60)
In Eq (10.7.58), (10.7.59) and (10.7.60) the subscripts x and y, combined with subscripts b, m and e, indicate the axis of bending about which a particular stress or design property applies, and
$$
F'_e = \frac{12 \pi^2 E}{23(Kl_b/r_b)^2}
$$
\= Euler stress divided by a factor of safety, N/mm². (In the expression for Fₑ', lₒ is the actual unbraced length in the plane of bending and rᵦ is the corresponding radius of gyration. K is the effective length factor in the plane of bending.) As in the case of Fₐ, Fbx and 0.60Fₘ, Fₐ, may be increased ¼ in accordance with Sec 10.7.2.2.
a) For compression members in frames subject to joint translation (sideway), Cm = 0.85.
b) For rotationally restrained compression members in frames braced against joint translation and not subject to transverse loading between their supports in the plane of bending,
$$
C_m = 0.6 - 0.4(M_1/M_2)
$$
where M₁/M₂ is the ratio of the smaller to larger moments at the ends of that portion of the member unbraced in the plane of bending under consideration. M₁/M₂ is positive when M₁ and M₂ have the same sign (reverse curvature, negative when bent in single curvature.
c) For compression members in frames braced against joint translation in the plane of loading and subjected to transverse loading between their supports, the value of Cm may be determined by an analysis. However, in lieu of such analysis, the following values are permitted :
i) For members whose ends are restrained against rotation in the plane of bending Cm = 0.85
ii) For members whose ends are unrestrained against rotation in the plane of bending Cm = 1.0.
#### 10.7.8.2 Axial Tension and Bending
Members subject to both axial tension and bending stresses shall be proportioned at all points along their length to satisfy the following equation :
$$
\frac{f_a}{F_t} + \frac{f_{bx}}{F_{bx}} + \frac{f_{by}}{F_{by}} ≤ 1.0
$$
(10.7.61)
where fb is the computed bending tensile stress, fs is the computed axial tensile stress, Fb is the allowable bending stress and Ft is the governing allowable tensile stress defined in Sec 10.7.4.1.
However, the computed bending compressive stress arising from an independent load source relative to the axial tension, taken alone, shall not exceed the applicable value required in Sec 10.7.6.
### 10.7.9 Design of Trusses
#### 10.7.9.1 General
Trusses are composed of individual members connected by welds, rivets or bolts.
#### 10.7.9.2 Purlins
The spacing of purlins shall be determined on the basis of the maximum safe span of the roof covering. If roof covering is supported through battens and common rafters, the purlins shall preferably be located at the panel points of the truss, by varying the spacing and size of battens and common rafters.
#### 10.7.9.3 Design of Members
a) Compression Members : All members under compressive forces shall be designed to satisfy the requirements of Sec 10.7.5.
b) Tension Members : All members under tensile forces shall be designed to satisfy the requirements of Sec 10.7.4.
#### 10.7.9.4 Joints and Connections
Joints and connections in trusses shall satisfy the requirements of Sec 10.9.
#### 10.7.9.5 Deflection and Camber
a) Deflection : Deflection due to service live load plus impact load, if any, shall be limited so as not to impair serviceability.
b) Camber : Trusses shall be provided with camber in accordance with Sec 10.10.1.
#### 10.7.9.6 Bracing : Trusses shall be adequately braced against instability.
### 10.7.10 Composite Construction
This section covers the design and construction of steel beams supporting a reinforced concrete slab so interconnected that the beams and the slab act together to resist bending. Simple and continuous composite beams with shear connectors and concrete-encased beams, constructed with or without temporary shores, are included.
#### 10.7.10.1 General Requirements
Composite members may either be totally encased members which depend upon natural bond for interaction with the concrete or those with shear connectors (mechanical anchorage to the slab) with the steel member not necessarily encased.
A beam totally encased in concrete cast integrally with the slab may be assumed to be connected to the concrete by natural bond, without additional anchorage, provided that :
a) Concrete cover over beam sides and soffit is at least 50 mm.
b) The top of the beam is at least 40 mm below the top and 50 mm above bottom of the slab.
c) Concrete encasement contains adequate mesh or other reinforcing steel throughout the whole depth and across the soffit of the beam to prevent spalling of the concrete.
Shear connectors must be provided for composite action if the steel member is not totally encased in concrete. The portion of the effective width of the concrete slab on each side of the beam centre line shall not exceed :
a) One-eighth of the beam span, centre to centre of supports;
b) One-half the distance to the centre line of the adjacent beam; or
c) The distance from the beam centre line to the edge of the slab.
#### 10.7.10.2 Design Assumptions
a) Encased beams shall be proportioned to support, unassisted, all dead loads applied prior to the hardening of the concrete (unless these loads are supported temporarily on shoring) and, acting in conjunction with the slab, to support all dead and live loads applied after hardening of the concrete, without exceeding a computed bending stress of 0.66fy, where Fy is the yield stress of the steel beam. The bending stress produced by loads after the concrete has hardened shall be computed on the basis of the sections and sectional properties of the composite section. Concrete tension stresses shall be neglected. Alternatively, the steel beam alone may be proportioned to resist, unassisted, the positive moment produced by all loads, live and dead, using a bending stress equal to 0.76 Fy in which case temporary shoring is not required.
b) When shear connectors are used in accordance with Sec 10.7.10.4, the composite section shall be proportioned to support all of the loads without exceeding the allowable stresses prescribed in 10.7.6.3(a), even when the steel section is not shored during construction. In limited areas (Sec 10.7.6.3), the stress in the composite section shall be exempt from compact flange criteria (Sec 10.7.3) and there is no limit on the unsupported length of the compression flange.
Reinforcement parallel to the beam within the effective width of the slab, when anchored in accordance with the requirements of Chapter 8, may be included in computing the properties of composite sections, provided that shear connectors are furnished in accordance with the requirements of Sec 10.7.10.4. The section properties of the composite section shall be computed in accordance with the elastic theory. Concrete tension stresses shall be neglected. For stress and deflection computations, the compression area of concrete shall be treated as an equivalent area of steel by dividing it by the modular ratio when determining section properties.
In cases where it is not feasible or necessary to provide adequate connectors to satisfy the horizontal shear requirements for full composite action, the effective section modulus shall be determined as
$$
S_{eff} = S_s + \sqrt{\frac{V'_h}{V_h}}(S_{tr} - S_s)
$$
(10.7.62)
where
$V_h$ and $V_h'$ are as defined in Sec 10.7.10.4.
For composite beams constructed without temporary shoring, stresses in the steel section shall not exceed 0.90$F_y$. Stresses shall be computed assuming that the steel section alone resists all loads applied before the concrete has reached 75% of its required strength and the effective composite section resists all loads applied after that time.
The actual section modulus of the transformed composite section shall be used in calculating the concrete flexural compression stress and for construction without temporary shores; this stress shall be based upon loading applied after the concrete has reached 75% of its required strength. The stress in the concrete shall not exceed 0.45$f'_c$
#### 10.7.10.3 End Shear
The web and the end connections of the steel beam shall be designed to carry the total reaction.
#### 10.7.10.4 Shear Connectors
Except in the case of encased beams, as defined in Sec 10.7.10.2(a), the entire horizontal shear at the junction of the steel beam and the concrete slab shall be assumed to be transferred by shear connectors welded to the top flange of the beam and embedded in the concrete. For full composite action with concrete subject to flexural compression, the total horizontal shear to be resisted between the point of maximum positive moment and points of zero moment shall be taken as the smaller value using Eq (10.7.63) and (10.7.64).
$$
V_h = 0.85 f'_c A_c / 2
$$
(10.7.63)
and
$$
V_h = F_y A_s / 2
$$
(10.7.64)
In continuous composite beams where longitudinal reinforcing steel is considered to act compositely with the steel beam in the negative moment regions, the total horizontal shear to be resisted by shear connectors between an interior support and each adjacent point of contraflexure shall be taken as
$$
V_h = F_{yr} A_{sr} / 2
$$
(10.7.65)
For full composite action, the number of connectors resisting the horizontal shear, $V_h$, on each side of the point of maximum moment, shall not be less than that determined by the relationship $V_h/q$, where $q$, the allowable shear load for one connector, is given in Table 6.10.3 for flat soffit concrete slabs made with ASTM C33 aggregates.
For partial composite action with concrete subjected to flexural compression, the horizontal shear $V'_h$ to be used in computing $S_{eff}$ shall be taken as the product of $q$ and the number of connectors furnished between the point of maximum moment and the nearest point of zero moment.
The value of $V'_h$ shall not be less than, $\frac{1}{4}$ the smaller value of Eq (10.7.63), using the maximum permitted effective width of the concrete flange, and Eq (10.7.64). The effective moment of inertia for deflection computations shall be determined by :
$$
I_{eff} = I_s + \sqrt{\frac{V'_h}{V_h}}(I_{tr} - I_s)
$$
(10.7.66)
The connectors required on each side of the point of maximum moment in an area of positive bending may be uniformly distributed between that point and adjacent points of zero moment, except that $N_2$, the number of shear connectors required between any concentrated load in that area and the nearest point of zero moment, shall be not less than that determined by Eq (10.7.67).
**Table 6.10.3**
**Allowable Horizontal Shear Load for One Connector (q), kN⁽¹⁾**
| Connector⁽²⁾ | 20 | 25 | ≥ 27.5 |
| :-------------------------------- | :- | :- | :----- |
| 12 dia × 50 hooked or headed stud | 22 | 24 | 26 |
| 16 dia × 65 hooked or headed stud | 35 | 38 | 40 |
| 20 dia × 75 hooked or headed stud | 51 | 55 | 59 |
| 22 dia × 90 hooked or headed stud | 70 | 75 | 80 |
Specified Compressive Strength of Concrete ($f'_c$), N/mm² — columns above correspond to 20, 25, and ≥ 27.5.
Notes: (1) Applicable only to concrete made with ASTM C33 aggregates. (2) The allowable horizontal loads tabulated are also permitted for studs longer than shown.
$$
N_2 = \frac{N_1\left[\dfrac{M\beta - 1}{M_{\max}}\right]}{\beta - 1}
$$
(10.7.67)
where
$$
\beta = \frac{S_{tr}}{S_s} \text{ or } \frac{S_{eff}}{S_s} \text{ as applicable}
$$
For a continuous beam, connectors required in the region of negative bending may be uniformly distributed between the point of maximum moment and each point of zero moment.
Shear connectors shall have at least 25 mm of lateral concrete cover, except for connectors installed in the ribs of formed steel decks. Unless located directly over the web, the diameter of studs shall not be greater than $2\frac{1}{2}$ times the thickness of the flange to which they are welded. The minimum centre to centre spacing of stud connectors shall be 6 diameters along the longitudinal axis of the supporting composite beam and 4 diameters transverse to the longitudinal axis of the supporting composite beam. The maximum centre to centre spacing of stud connectors shall not exceed 8 times the total slab thickness.
#### 10.7.10.5 Composite Beams or Girders with Formed Steel Deck
Composite construction of concrete slabs on formed steel deck with nominal rib height not greater than 75 mm connected to steel beams or girders shall be designed by the applicable portions of Sec 10.7.10.1 through 10.7.10.4 with the following modifications.
a) General :
i) The average width of concrete rib or haunch wᵣ, shall be not less than 50 mm, but shall not be taken in calculations as more than the minimum clear width near the top of the steel deck. For additional provisions see c(i) and c(iii) below.
ii) The concrete slab shall be connected to the steel beam or girder with welded stud shear connectors 20 mm or less in diameter. Studs may be welded through the deck or directly to the steel member.
iii) Stud shear connectors shall extend not less than 40 mm above the top of the steel deck after installation.
iv) The slab thickness above the steel deck shall not be less than 50 mm.
b) Deck Ribs Oriented Perpendicular to Beam or Girder
i) Concrete below the top of the steel deck shall be neglected when determining section properties and in calculating Aᶜ for Eq (10.7.63).
ii) The spacing of stud shear connectors along the length of a supporting beam or girder shall not exceed 900 mm.
iii) The allowable horizontal shear load per stud connector q shall be the value stipulated in Sec 10.7.10.4 (Table 6.10.3) multiplied by the following reduction factor :
$$
\left(\frac{0.85}{\sqrt{N_r}} \right) \left(\frac{H_s}{h_r} \right) \left(\frac{H_s}{h_r} - 1.0\right) ≤ 1.0
$$
(10.7.68)
where
* $N_r$ shall not exceed 3 in computations, although more than 3 studs may be installed.
* $H_s$ shall not exceed the value $(h_r + 75)$ in computations, although the actual length may be greater.
c) Deck Ribs Oriented Parallel to Beam or Girder
i) Concrete below the top of the steel deck shall be included when determining section properties and in calculating Aᶜ for Eq (10.7.63).
ii) Steel deck ribs over supporting beams or girders may be split longitudinally and separated to form a concrete haunch.
iii) When the nominal depth of steel deck is 40 mm or greater, the average width wᵣ, of the supported haunch or rib shall be not less than 50 mm for the first stud in transverse row plus 4 stud diameters for each additional stud.
iv) The allowable horizontal shear load per stud connector q shall be the value stipulated in Sec 10.7.10.4 (Table 6.10.3) except when the ratio wᵣ/hᵣ is less than 1.5, the allowable load shall be multiplied by the following reduction factor :
$$
0.6\left(\frac{w_r}{h_r}\right)\left(\frac{H_s}{h_r} - 1.0\right) ≤ 1.0
$$
(10.7.69)
where
* Nᵣ shall not exceed 3 in computations.
* Hₛ shall not exceed the value (hᵣ + 75) in computations, although the actual length may be greater.
### 10.7.11 Special Design Considerations
This section provides the design considerations related to special situations such as concentrated loads, ponding and torsion.
#### 10.7.11.1 Webs and Flanges Under Concentrated Loads
a) Design Basis : Members with concentrated loads applied normal to one flange and symmetric to the web shall have a flange and web proportioned to satisfy the local flange bending, web yielding strength, web crippling and column web buckling criteria of (b) through (e) below. Members with concentrated loads applied to both flanges shall have a web proportioned to satisfy the web yielding, web crippling and column web buckling criteria of (c), (d) and (f) below.
Where pairs of stiffeners are provided on opposite sides of the web, at concentrated loads, and extend at least half the depth of the member, provision of (b) and (c) below need not apply.
For column webs subjected to high shears, see (g) below, and for bearing stiffeners, see (h) below.
b) Local Flange Bending : A pair of stiffeners shall be provided opposite the tension flange or flange plate of the beam or girder framing into the member when
$$
t_f < 12.65 \sqrt{\frac{P_{bf}}{F_{yc}}}
$$
(10.7.70)
where
$P_{bf}$ = the computed force delivered by the flange or moment connection plate multiplied by $\frac{3}{4}$, when the computed force is due to live and dead load only, or by $\frac{2}{3}$, when the computed force is due to live and dead load in conjunction with wind or earthquake forces, kN.
When the length of loading measured across the member flange is less than 0.15b, Eq (10.7.70) need not be checked.
c) Local Web Yielding : Bearing stiffeners shall be provided in beams and welded plate girders if the compressive stress at the web toe of the fillets resulting from concentrated loads exceeds 0.66Fy.
i) When the force to be resisted is a concentrated load producing tension or compression applied at a distance from the member end that is greater than the depth of the member,
$$
\frac{1000R}{t_w(N + 5k)} ≤ 0.66F_y
$$
(10.7.71)
ii) When the force to be resisted is a concentrated load at or near the end of the member,
$$
\frac{1000R}{t_w(N + 2.5k)} ≤ 0.66F_y
$$
(10.7.72)
d) Web Crippling : Bearing stiffeners shall be provided in the webs of members under concentrated loads, when the compressive force exceeds the following limits :
i) When the concentrated load is applied at a distance not less then d/2 from the end of the member :
$$
R = 0.1771t_c^2 \left[ 1 + 3\left(\frac{N}{d}\right)\left(\frac{t_w}{t_f}\right)^{1.5} \right] \sqrt{\frac{F_{yw}}{f_{f/w}}}
$$
(10.7.73)
ii) When the concentrated load is applied less than a distance d/2 from the end of the member :
$$
R = 0.0891t_c^2 \left[ 1 + 3\left(\frac{N}{d}\right)\left(\frac{t_w}{t_f}\right)^{1.5} \right] \sqrt{\frac{F_{yw}}{f_{f/w}}}
$$
(10.7.74)
If stiffeners are provided and extend at least one-half the web depth, Eq (10.7.73) and (10.7.74) need not be checked.
#### 10.7.11.2 Ponding
The roof system shall be investigated by structural analysis to assure adequate strength and stability under ponding conditions, unless the roof surface is provided with sufficient slope toward points of free drainage or adequate individual drains to prevent the accumulation of rainwater. The roof system shall be considered stable and not requiring further investigation if :
$$
C_p + 0.9C_s ≤ 0.25
$$
(10.7.79)
and
$$
I_d ≥ 3955(S)^4
$$
(10.7.80)
where
$$
C_p = \frac{506L_s I_s^4}{I_p}
$$
$$
C_s = \frac{5065L_s^4}{I_s}
$$
For trusses and steel joists, the moment of inertia Iₛ shall be decreased 15% when used in the above equation. A steel deck shall be considered a secondary member when it is directly supported by the primary members.
Total bending stress due to dead loads, gravity live loads (if any) and ponding shall not exceed 0.80Fy, for primary and secondary members. Stresses due to wind or seismic forces need not be included in a ponding analysis.
#### 10.7.11.3 Torsion
The effects of torsion shall be considered in the design of members and the normal and shearing stresses due to torsion shall be added to those from all other loads, with the resultants not exceeding the allowable values.
## 10.8 LOAD FACTOR DESIGN METHOD
### 10.8.1 General
This section provides the specifications for design and construction of steel buildings using Load Factor Design method.
### 10.8.2 Basis of Design
#### 10.8.2.1 Required Strength for Factored Loads
The required strength of structural members and connections shall be determined by structural analysis for the combinations of appropriate factored loads stipulated in Sec 10.8.2.4.
Design by either elastic or plastic analysis is permitted except that plastic analysis is permitted only for steels with yield stress not exceeding 450 N/mm² and shall comply with provision of Sec 10.8.3.2, 10.5.2, 10.8.6.1(b), 10.8.6.1(a), 10.8.8.1 and 10.8.11.
Except for hybrid girders and members of A514 steel, beams and girders which are continuous over support or are rigidly framed to columns by means of rivets, high strength bolts or welds may be proportioned for $\frac{1}{12}$ of the maximum negative moments at the support provided that the maximum positive moment at mid-span shall be increased by $\frac{1}{12}$ of the average negative moments. This reduction is not allowed for cantilever moments. If the negative moment is resisted by a column rigidly framed to the beam or girder, the $\frac{1}{12}$ reduction may be used in proportioning the column for the combined axial and bending loading, provided that the stress fₐ due to any concurrent axial load on the member, does not exceed 0.15 Fₐ.
#### 10.8.2.2 Limit States
The members shall be of such size and strength that no applicable limit state is exceeded when the structure is designed for appropriate factored loads and their combinations stipulated in Sec 10.8.2.4.
Strength limit states are related to safety and maximum load carrying capacity whereas serviceability limit states are related to performance under normal service conditions. The term "resistance" includes both strength limit states and serviceability limit states.
#### 10.8.2.3 Design for Strength
The design strength of each structural component or assemblage must equal or exceed the required strength based on the factored design loads. The design strength φ Rₙ is calculated for each applicable limit state as the nominal strength Rₙ multiplied by a resistance factor φ. The required strength is determined for each applicable load combination according to Sec 10.8.2.4.
#### 10.8.2.4 Loads and Load Combinations
The design loads shall be the minimum factored loads and their combinations as stipulated in Chapter 2, Loads.
#### 10.8.2.5 Design for Serviceability
The overall structure and individual members, connections and connectors shall be checked for serviceability according to the requirements of Sec 10.10.
### 10.8.3 Local Buckling
#### 10.8.3.1 Classification of Steel Sections
Steel sections are classified as compact, noncompact and slender element sections. For a section to qualify as compact, its flanges must be continuously connected to the web or webs and the width-thickness ratio of its compression elements shall not exceed the applicable limiting width-thickness ratios given in Table 6.10.4. If the width-thickness ratio of one or more compression elements exceeds the values for compact section given in Table 6.10.4, the section shall be treated as noncompact provided the width-thickness ratio does not exceed the value for noncompact section given in the same table. If the width-thickness ratio of any compression element exceeds the noncompact values given in Table 6.10.4, the section is classified as a slender element section.
a) For unstiffened elements which are supported along only one edge, parallel to the direction of the compression force, the width shall be taken as follows:
i) For flanges of I-shaped members and tees, the width b is half the full nominal width.
ii) For legs of angles and flanges of channels and zees, the width b is the full nominal dimension.
iii) For plates, the width b is the distance from the free edge to the first row of fasteners or line of welds.
iv) For stems of tees, d is taken as the full nominal depth.
b) For stiffened elements, i.e., supported along two edges parallel to the direction of the compression force, the width shall be taken as follows:
i) For webs of rolled or formed sections, h is the clear distance between flanges less the fillet or corner radius at each flange; hc is twice the distance from the neutral axis to the inside face of the compression flange less the fillet or corner radius.
ii) For webs of built-up sections, h is the distance between adjacent lines of fasteners or the clear distance between flanges when welds are used, and hc is twice the distance from the neutral axis to the nearest line of fasteners at the compression flange or the inside face of the compression flange when welds are used.
iii) For flange or diaphragm plates in built-up sections, the width b is the distance between adjacent lines of fasteners or the clear distance between flanges when welds are used.
iv) For flanges of rectangular hollow structural sections, the width b is the clear distance between webs less the inside corner radius on each side. If the corner radius is not known, the flat width may be taken as the total section width minus three times the thickness.
c) For tapered flanges of rolled sections, the thickness is the nominal value halfway between the free edge and the corresponding face of the web.
#### 10.8.3.2 Section for Plastic Analysis
Plastic analysis is permitted when flanges subjected to compression involving hinge rotation and all webs and flange slenderness ratios less than the limiting value for compact section from Table 6.10.4. For circular hollow sections refer to note (4) of Table 6.10.4. Plastic analysis is subject to the limitations as outlined in Sec 10.8.2.1.
### 10.8.4 Design of Tension Members
This section specifies the requirements for design of prismatic members subjected to axial tension due to static forces acting through the centroidal axis.
#### 10.8.4.1 Design Tensile Strength
The design tensile strength of a member φₜ Pₙ shall be the lesser of the value obtained using the limit states of yielding in the gross section and fracture in the net section.
a) For yielding in the gross section :
$$
φ_t = 0.90
$$
$$
P_n = 0.001 F_y A_g
$$
(10.8.1)
b) For fracture in the net section :
$$
φ_t = 0.75
$$
$$
P_n = 0.001 F_u A_e
$$
(10.8.2)
When members without holes are fully connected by welds, the effective net section used in Eq (10.8.2) shall be comprised using the entire area of the member or the effective area of the welds as defined in Sec 10.9.2. When holes are present in a welded member between end connections or at the welded connection in the case of plug or slot welds, the net section through the holes shall be used in Eq (10.8.2).
#### 10.8.4.2 Built-up Members
The longitudinal spacing of connectors between elements in continuous contact consisting of a plate and a shape or two plates shall not exceed
a) 24 times the thickness of the thinner plate or 300 mm for painted members or unpainted members not subject to corrosion.
b) 14 times the thickness of the thinner plate or 175 mm for unpainted members of weathering steel subject to atmospheric corrosion.
The longitudinal spacing of connectors between components should preferably limit the slenderness ratio in any component between the connectors to 300 or less.
Either perforated cover plates or tie plates without lacing may be used on the open sides of built-up tension members. Tie plates shall have a length not less than $\frac{2}{3}$ the distance between the lines of welds or fasteners connecting them to the components of the member. The thickness of such tie plates shall not be less than $\frac{1}{4}$ of the distance between these lines. The longitudinal spacing of intermittent welds or fasteners at the plates shall not exceed 150 mm. The spacing of tie plates shall be such that the slenderness ratio of any component in the length between tie plates shall not exceed 300 mm.
#### 10.8.4.3 Eyebars and Pin-connected Members
The design strength of eyebars shall be determined as in Sec 10.8.4.1(a) with Aₛ taken as the cross-sectional area of the body.
Eyebars shall be of uniform thickness, without reinforcement at the pin holes, and have circular heads whose periphery is concentric with the pin hole.
The radius of transition between the circular head and the eyebar body shall be not less than the head diameter.
The width of the body of the eyebars shall not exceed eight times its thickness. The thickness can be less than 12 mm only if external nuts are provided to tighten pin plates and filler plates into snug contact. The width b from the hole edge to the plate edge perpendicular to the direction of applied load shall be greater than $\frac{2}{3}$ and, for the purpose of calculation, not more $\frac{3}{4}$ times the eyebar body width.
The pin diameter shall not be less than $\frac{7}{8}$ times the eyebar body width.
The pin hole diameter shall not be more than 1 mm greater than the pin diameter.
For steels having a yield stress greater than 480 N/mm², the hole diameter shall not exceed five times the plate thickness and the width of the eyebar body shall be reduced accordingly.
In pin-connected members in which the pin is expected to provide for relative rotation while under full load, the diameter of pin hole shall not be more than 1 mm greater than the diameter of the pin. The width of the plate beyond the pin hole shall be not less than pin hole shall be not less than $\frac{2}{3}$ of the net area required for strength across the pin hole.
In pin-connected plates others than eyebars, the design strength shall be determined according to Eq (10.8.2) and the bearing strength of the projected area of the pin shall be determined according to Sec 10.9.8.2. The
### 10.8.5 Design of Columns and Other Compression Members
This section covers the design of prismatic members subjected to axial compression through the centroidal axis.
#### 10.8.5.1 Effective Lengths and Slenderness Limitations
a) Effective Length : The effective length factor K shall be determined in accordance with Sec 10.5.2.
b) Plastic Analysis : Plastic analysis, as limited in Sec 10.8.2.1 is permitted if the column slenderness parameter λc defined by Eq (10.8.9) does not exceed 1.5K.
#### 10.8.5.2 Design Compressive Strength
The design strength of compression members whose elements have a width-thickness ratio less than the noncompact values of Table 6.10.4 is φc Pₙ, where
$$
φ_c = 0.85
$$
$$
P_n = 0.001 A_g F_{cr}
$$
(10.8.6)
For $λ_c ≤ 1.5$
$$
F_{cr} = \left( 0.658^{λ_c^2} \right) F_y
$$
(10.8.7)
For $λ_c > 1.5$
$$
F_{cr} = \left[ \frac{0.877}{λ_c^2} \right] F_y
$$
(10.8.8)
where
$$
λ_c = \frac{Kl}{r π} \sqrt{\frac{F_y}{E}}
$$
(10.8.9)
For slender sections, as classified in Sec 10.8.3.1, the design shall conform to the requirements of Sec 10.8.5.6.
#### 10.8.5.3 Flexural Torsional Buckling
Singly symmetric and unsymmetric columns, such as angle or tee-shaped columns, and doubly symmetric columns such as cruciform or built-up columns with very thin walls, may require consideration of the limit states of flexural-torsional and torsional buckling.
The strength of compression members determined by the limit state of torsional and flexural-torsional buckling is φcPₙ , where
$$
φ_c = 0.85
$$
$$
P_n = 0.001A_g F_{cr}
$$
(10.8.10)
$Q$ = 1.0 for elements meeting the width-thickness ratios, for noncompact values from Table 6.10.4.
\= $Q_sQ_a$ for elements not meeting the width-thickness ratios for noncompact values from Table 6.10.4 and determined in accordance with the provisions of Sec 10.8.5.6.
The nominal critical stress Fcr is determined as follows:
a) For $λ_e \sqrt{Q} ≤ 1.5$ :
$$
F_{cr} = \left( Q\,0.658^{Qλ_e^2} \right) F_y
$$
(10.8.11)
b) For $λ_e \sqrt{Q} > 1.5$ :
$$
F_{cr} = \left[ \frac{0.877}{λ_e^2} \right] F_y
$$
(10.8.12)
where
$$
λ_e = \sqrt{\frac{F_y}{F_e}}
$$
(10.8.13)
The critical torsional or flexural-torsional elastic buckling stress Fₑ is determined as follows:
a) For doubly symmetric shapes the critical torsional elastic buckling stress is
$$
F_e = \frac{π^2 EC_w}{(K_s L)^2} + GJ \frac{1}{I_x + I_y}
$$
(10.8.14)
b) For singly symmetric shapes, where y is the axis of symmetry, the critical flexural-torsional elastic buckling stress is
$$
F_e = \frac{F_{cy} + F_cz}{2H} \left[ 1 - \sqrt{1 - \frac{4F_{cy}F_{cz}H}{(F_{cy} + F_{cz})^2}} \right]
$$
(10.8.15)
c) For unsymmetric shapes, the critical flexural-torsional elastic buckling stress Fₑ is the smallest root of the cubic equation
$(F_c - F_ex)(F_c - F_ey)(F_c - F_ez) - F_c^2(F_c - F_ey)(x_o/r_o)^2 - F_c^2(F_c - F_ex)(y_o/r_o)^2 = 0$
(10.8.16)
In Eq (10.8.14), (10.8.15), (10.8.16) above,
$$
r_o^2 = x_o^2 + y_o^2 + \frac{I_x + I_y}{A}
$$
(10.8.17)
$$
H = 1 - \left( \frac{x_o^2 + y_o^2}{r_o^2} \right)
$$
(10.8.18)
$$
F_{cx} = \frac{π^2 E}{(K_x L/r_x)^2}
$$
(10.8.19)
$$
F_{cy} = \frac{π^2 E}{(K_y L/r_y)^2}
$$
(10.8.20)
$$
F_{cz} = \frac{π^2 EC_w}{(K_s L)^2} + GJ \frac{1}{A r_o^2}
$$
(10.8.21)
#### 10.8.5.4 Built-up Members
At the ends of built-up compression members bearing on base plates or milled surfaces, all components in contact with one another shall be connected by a weld having a length not less than the maximum width of the member. For intermediate connections required by sections below, spacing between the connectors or bolts, or both, shall be spaced longitudinally no more than four diameters apart for a distance equal to 1½ times the maximum width of the member.
Along the length of built-up compression members between the end connections required above, longitudinal spacing for intermediate welds, bolts or rivets shall be such that the web shear stress along the length of the web will not exceed the value permitted. However, where a component of a built-up compression member consists of an outside plate, except as provided in the next sentence, the maximum spacing shall not exceed the thickness of the thinner outside plate nor 300 mm, when intermittent welds are provided along the edges of the components or when fasteners are provided on all gauge lines at each section. When fasteners are staggered, the maximum spacing on each gauge line shall not exceed the thickness of the thinner outside plate times $\frac{500}{\sqrt{F_y}}$, nor 450 mm .
For unpainted built-up members made of weathering steel which will be exposed to atmospheric corrosion, the fasteners connecting a plate and a shape or two-plate components in contact with one another shall not exceed 14 times the thickness of the thinnest part nor 175 mm and the maximum end distance shall not exceed eight times the thickness of the thinnest part nor 125 mm.
Compression members composed of two or more shapes shall be connected to one another at intervals such that the slenderness ratio L/r of either shape, between the fasteners, does not exceed the governing slenderness ratio of the built-up members. The least radius of gyration r shall be used in computing the slenderness ratio of each component part.
The design strength of built-up members composed of two or more shapes shall be determined in accordance with Sec 10.8.5.2 or 10.8.5.3 subject to the following modification. If the bulking mode involves relative deformation that produces shear forces in the connectors between individual shapes, K/r is replaced by $(K/r)_m$ determined as follows:
a) For Snug-tight Bolted Connectors :
$$
\left( \frac{Kl}{r} \right)_m = \sqrt{\left( \frac{Kl}{r} \right)_o^2 + \left( \frac{a}{r_i} \right)^2}
$$
(10.8.22)
b) For Welded Connectors and for Fully Tightened Bolted Connectors as required for Slip-critical Joints:
with $\frac{a}{r_i} > 50$ :
$$
\left( \frac{Kl}{r} \right)_m = \sqrt{\left( \frac{Kl}{r} \right)_o^2 + \left( \frac{a}{r_i} - 50 \right)^2}
$$
(10.8.23)
with $\frac{a}{r_i} ≤ 50$ :
$$
\left( \frac{Kl}{r} \right)_m = \left( \frac{Kl}{r} \right)_o
$$
(10.8.24)
where
$(Kl/r)_o$ = column slenderness of built-up members acting as a unit
$a/r_i$ = larger column slenderness of individual components
$(Kl/r)_m$ = modified column slenderness of built-up members
$a$ = distance between connectors, mm
$r_i$ = minimum radius of gyration of individual component
Open sides of compression members built up from plates or shapes shall be provided with continuous cover plates perforated with a succession of access holes. The unsupported width of such plates at access holes, as defined in Sec 10.8.3.1 is assumed to contribute to the design strength provided that:
i) The width-thickness ratio conforms to the limitations of Sec 10.8.3.1.
ii) The ratio of length (in direction of stress) to width of hole shall not exceed 2.
iii) The clear distance between holes in the direction of stress shall not be less than the transverse distance between nearest line of connecting fasteners or welds.
iv) The periphery of the holes at all points shall have a minimum radius of 40 mm.
The function of perforated cover plates may be performed by lacing with tie plates at each end and at intermediate points if the lacing is interrupted. Tie plates shall be as near the ends as practicable. In main members providing design strength, the end tie plates shall have a length of not less than the distance between the lines of fasteners or welds connecting them to the components of the member. Intermediate tie plates shall have a length of not less than $\frac{1}{2}$ of this distance. The thickness of tie plates shall be not less than $\frac{1}{50}$ of the distance between lines of welds or fasteners connecting them to the segments of the members. In welded construction, the welding on each line connecting a tie plate shall in aggregate be not less than $\frac{1}{3}$ the length of the plate. In bolted and riveted construction, the spacing in the direction of stress in tie plates shall be not more than 6 diameters and the tie plates shall be connected to each segment by at least three fasteners.
Lacing, including flat bars, angles, channels or other shapes employed as lacing, shall be so spaced that the L/r ratio of the flange included between their connections shall not exceed the governing slenderness ratio for the member as a whole. Lacing shall be proportioned to provide a shearing strength normal to the axis of the member equal to 2% of the compressive design strength of the member. The L/r ratio for lacing bars arranged in single systems shall not exceed 140. For double lacing this ratio shall not exceed 200. Double lacing bars shall be joined at their intersections. For lacing bars in compression, L may be taken as the unsupported length of the lacing bar between welds or fasteners connecting it to the components of the built-up member for single lacing, and 70% of that distance for double lacing. The inclination of lacing bars to the axis of the member shall preferably be not less than 60° for single lacing and 45° for double lacing. When the distance between the lines of welds or fasteners in the flanges is more than 375 mm, the lacing shall preferably be double or be made of angles.
#### 10.8.5.5 Pin-Connected Compression Members
Pin-connections of pin-connected compression members shall conform to the requirements of Sec 10.8.4.3 except Eq (10.8.3) and (10.8.4) do not apply.
#### 10.8.5.6 Slender Compression Elements
Axially loaded members containing elements subjected to compression which have a width-thickness ratio in excess of the noncompact values as stipulated in Sec 10.8.3.1 shall be designed in accordance with this section. Flexural members with slender compression elements shall be designed in accordance with Sec 10.8.6.1(f). Rolled flexural members with proportions not covered by Sec 10.8.6.1(f) shall be designed in accordance with this section.
a) Unstiffened Compression Elements : The design strength of unstiffened compression elements whose width-thickness ratio exceeds the applicable value for noncompact sections as stipulated in Sec 10.8.3.1 shall be subject to a reduction factor $Q_s$. The value of $Q_s$ shall be determined by Eq (10.8.25) through (10.8.30) as applicable. When such elements comprise the compression flange of a flexural member, the maximum required bending stress shall not exceed $\phi_b F_y Q_s$, where $\phi_b = 0.90$. The design strength of axially loaded compression members shall be modified by the appropriate reduction factor $Q_s$, as provided in (c) below.
For single angles :
When $\frac{200}{\sqrt{F_y}} < b/t < \frac{407}{\sqrt{F_y}}$
$$
Q_s = 1.340 - 0.0017(b/t)_i \sqrt{F_y}
$$
(10.8.25)
When $b/t ≥ \frac{407}{\sqrt{F_y}}$
$$
Q_s = \frac{106867}{F_y (b/t)^2}
$$
(10.8.26)
For angles of plates projecting from columns or other compression members, and for projecting elements of compression flanges of girders :
When $\frac{250}{\sqrt{F_y}} < b/t < \frac{462}{\sqrt{F_y}}$
$$
Q_s = 1.415 - 0.00166(b/t)_i \sqrt{F_y}
$$
(10.8.27)
When $b/t ≥ \frac{462}{\sqrt{F_y}}$
$$
Q_s = \frac{137890}{F_y (b/t)^2}
$$
(10.8.28)
For stems of tees :
When $\frac{333}{\sqrt{F_y}} < b/t < \frac{462}{\sqrt{F_y}}$
$$
Q_s = 1.908 - 0.0027(b/t)_i \sqrt{F_y}
$$
(10.8.29)
When $b/t ≥ \frac{462}{\sqrt{F_y}}$
$$
Q_s = \frac{137890}{F_y (b/t)^2}
$$
(10.8.30)
Unstiffened elements of tees whose proportions exceed the limits of Sec 10.8.3.1 shall conform to the limits given in Table 6.10.2.
b) Stiffened Compression Elements : When the width-thickness ratio of uniformly compressed stiffened elements (except perforated cover plates) exceeds the noncompact limit stipulated in Sec 10.8.3.1 a reduced effective width, bₑ, shall be used in computing the design properties of the section containing the element.
i) For flanges of square and rectangular sections of uniform thickness :
$$
b_e = \frac{856t}{\sqrt{f}} \left[ 1 - \frac{170}{(b/t)\sqrt{f}} \right] ≤ b
$$
(10.8.31)
ii) For other uniformly compressed elements :
$$
b_e = \frac{856t}{\sqrt{f}} \left[ 1 - \frac{150}{(b/t)\sqrt{f}} \right] ≤ b
$$
(10.8.32)
where
$b_e$ = reduced width, mm
$f$ = computed elastic compressive stress in the stiffened elements, based on the design properties as specified in (c) below, N/mm². If unstiffened elements are included in the total cross-section, $f$ for the stiffened element must be such that the maximum compressive stress in the unstiffened element does not exceed $\phi_c F_{cr}$ as defined in (c) below, with $Q = Q_s$ and $\phi_c = 0.85$, or $\phi_b F_y Q_s$ with $\phi_b = 0.90$, as applicable.
iii) For axially loaded circular sections :
Members with diameter to thickness ratios $D/t$ greater than $22752/F_y$, but having a diameter to thickness ratio of less than $89630/F_y$ ;
$$
Q = \frac{7584}{F_y(D/t)} + \frac{2}{3}
$$
(10.8.33)
c) Design Properties : Properties of sections shall be determined using the full cross-section, except as follows :
In computing the moment of inertia and elastic section modulus of flexural members, the effective width of uniformly compressed stiffened elements, as determined in (b) above, shall be used in determining effective cross-sectional properties.
For unstiffened elements of the cross-section, $Q_s$ is determined from (a) above. For stiffened elements of the cross-section
$$
Q_a = \frac{\text{effective area}}{\text{actual area}}
$$
(10.8.34)
where the effective area is equal to the summation of the effective areas of cross-section.
For axially loaded compression members the gross cross-sectional area and the radius of gyration $r$ shall be computed on the basis of the actual cross-section. However, when $\lambda_c\sqrt{Q} ≤ 1.5$, the critical stress $F_{cr}$ shall be determined by
$$
F_{cr} = Q\left(0.658^{Q\lambda_c^2}\right)F_y
$$
(10.8.35)
where Q is given by the following :
i) Cross-sections composed entirely of unstiffened elements, $Q = Q_s$
ii) Cross-sections composed entirely of stiffened elements, $Q = Q_a$
iii) Cross-sections composed of both stiffened and unstiffened elements, $Q = Q_s Q_a$
When $\lambda_c\sqrt{Q} > 1.5$, the critical stress $F_{cr}$ shall be determined by
$$
F_{cr} = \left[\frac{0.877}{\lambda_c^2}\right]F_y
$$
(10.8.36)
### 10.8.6 Design of Beams and Other Flexural Members
This section specifies the requirements for the design of singly or doubly symmetric beams including hybrid beams and girders loaded in the plane of symmetry, and channels loaded in a plane passing through the shear centre parallel to the web or restrained against twisting at load points and points of support.
#### 10.8.6.1 Design for Flexure
a) Unbraced Length for Plastic Analysis: Plastic analysis, as limited in Sec 10.8.2.1, is permitted when the laterally unbraced length Lp of the compression flange at plastic hinge locations associated with the failure mechanism, for a compact section bent about the major axis, does not exceed Lpd, determined as follows :
i) For doubly symmetric and singly symmetric I-shaped members with the compression flange larger than the tension flange (including hybrid members) loaded in the plane of the web
$$
L_{pd} = \frac{25000 + 15000(M_1/M_p)}{F_y}
$$
(10.8.37)
ii) For solid rectangular bars and symmetric box beams
$$
L_{pd} = \frac{34500 + 20700(M_1/M_p)}{F_y} F_y ≥ 20700σ_y/F_y
$$
(10.8.38)
There is no limit on Lb for members with circular or square cross-sections nor for any beam bent about its minor axis.
In the region of the last hinge to form, and in regions not adjacent to a plastic hinge, the flexural design strength shall be determined as in (b) below.
b) Flexural Design Strength: The flexural design strength, determined by the limit state of lateral-torsional buckling, is φbMₙ, where the nominal strength Mₙ shall be determined in accordance with the following sections, and φb = 0.90.
c) Compact Section Members with Lb ≤ Lr
For laterally unsupported compact section members bent about the major axis:
$$
M_n = C_b M_p - \left( M_p - M_r \right) \left( \frac{L_b - L_p}{L_r - L_p} \right) ≤ M_p
$$
(10.8.39)
where
* $C_b$ = 1.75+1.05(M₁/M₂)+0.3(M₁/M₂)² ≤ 2.3 where M₁ is the smaller and M₂ the larger end moment in the unbraced segment of the member; M₁/M₂ is positive when M₁ and M₂ have the same sign (reverse curvature bending) and negative when bent in single curvature.
* $C_b$ = 1.0 for unbraced cantilevers and for members where the moment within a significant portion of the unbraced segment is greater than or equal to the larger of the segment end moments.
* $L_p$ = distance between points braced against lateral displacement of the compression flange, or between points braced to prevent twist of the cross-section.
* $L_r$ = distance between points braced against lateral displacement of the compression flange, between points braced to prevent twist of the cross-section.
For I-shaped members including hybrid sections and channels bent about the major axis:
$$
L_p = \frac{790 r_y}{\sqrt{F_{yf}}}
$$
(10.8.40)
For solid rectangular bars and symmetric box sections:
$$
L_p = \frac{25.86 \times 10^{-3} r_y}{M_p} \sqrt{JA}
$$
(10.8.41)
The limiting laterally unbraced length Lr and the corresponding buckling moment Mr shall be determined as follows:
i) For I-shaped members, doubly symmetric and singly symmetric with the compression flange larger than the tension flange, and channels loaded in the plane of the web:
$$
L_r = \frac{r_y X_1}{F_{yw} - F_r} \sqrt{1 + \sqrt{1 + X_2(F_{yw} - F_r)^2}}
$$
(10.8.42)
$$
M_r = 10^{-6}(F_{yw} - F_r)S_x
$$
(10.8.43)
where
$$
X_1 = \frac{π}{S_x}\sqrt{\frac{EGJA}{2}}
$$
(10.8.44)
$$
X_2 = 4\frac{C_w}{I_y}\left(\frac{S_x}{GJ}\right)^2
$$
(10.8.45)
$F_r$ = compressive residual stress in flange; 70 N/mm² for rolled shapes, 114 N/mm² for welded shapes.
ii) For singly symmetric, I-shaped members with the compression flange larger than the tension flange, use $S_{xc}$ in place of $S_x$ in Eq (10.8.43) through (10.8.45).
iii) For symmetric box sections bent about the major axis and loaded in the plane of symmetry, M, and Lr shall be determined from Eq (10.8.43) and (10.8.46) respectively.
iv) For solid rectangular bars bent about major axis:
$$
L_r = \frac{0.393 r_y \sqrt{JA}}{M_r}
$$
(10.8.46)
$$
M_r = 10^{-6} F_y S_x
$$
(10.8.47)
d) Compact Section Members With Lₚ > Lr
For laterally unsupported members with compact section members bent about the major axis:
$$
M_n = M_{cr} ≤ C_b M_r
$$
(10.8.48)
Where Mcr is the critical elastic moment, determined as follows:
i) For I-shaped members, doubly symmetric and singly symmetric with compression flange larger than the tension flange (including hybrid members) and channels loaded in the plane of the web:
$$
M_{cr} = 10^{-6} C_b \frac{π}{L_b} \sqrt{EI_y GJ + \left( \frac{πE}{L_b} \right)^2 I_y C_w}
$$
(10.8.49)
$$
= 10^{-6} \frac{C_b S_x X_1 \sqrt{2}}{L_b/r_y} \sqrt{1 + \frac{X_1^2 X_2}{2 (L_b/r_y)^2}}
$$
ii) For solid rectangular bars and symmetric box sections:
$$
M_{cr} = \frac{0.393 C_b \sqrt{JA}}{L_b/r_y}
$$
(10.8.50)
e) Tees and Double-angle Beams: The nominal strength of tees and double-angle beams loaded in the plane of symmetry and bent about the major axis, with flange and web slenderness ratios less than the corresponding noncompact values given in Table 6.10.4.
$$
M_n = M_{cr} = 10^{-6} \frac{C_b π \sqrt{EI_y GJ}}{L_b} \left[ B ± \sqrt{1 + B^2} \right] ≤ M_y
$$
(10.8.51)
where
$$
B = ± 2.3\left( \frac{d}{L_b} \right) \sqrt{\frac{I_y}{J}}
$$
(10.8.52)
The plus sign for B applies when the stem is in tension and the minus sign applies when the stem is in compression.
f) Nominal Flexural Strength of Other Sections : There is no lateral-torsional buckling limit state for circular or square shapes nor for any shape bent about its minor axis.
The nominal strength $M_n$ of other types of cross-sections including noncompact sections or sections with slender elements, shall be determined as follows for each limit state:
For $λ ≤ λ_p$
$$
M_n = M_p
$$
(10.8.53)
For $λ_p < λ ≤ λ_r$:
For the limit state of lateral-torsional buckling:
$$
M_n = C_b \left[ M_p - \left(M_p - M_r\right)\left(\frac{λ - λ_p}{λ_r - λ_p}\right) \right] ≤ M_p
$$
(10.8.54)
For the limit states of flange and web local buckling:
$$
M_n = M_p - \left(M_p - M_r\right)\left(\frac{λ - λ_p}{λ_r - λ_p}\right)
$$
(10.8.55)
For $λ > λ_r$:
For the limit state of lateral-torsional buckling and for flange local buckling:
$$
M_n = M_{cr} = 10^{-6} S F_{cr}
$$
(10.8.56)
#### 10.8.6.2 Design for Shear
This section applies to the web (or webs in the case of multiple web members) of singly or doubly symmetric beams, including hybrid beams, subjected to shear in the plane of symmetry, and channels subjected to shear in the web. Where failure might occur by shear along a plane through fasteners, refer to Sec 10.9.4. For members subjected to high shear from concentrated loads, refer to Sec 10.8.11.1(g).
a) Web Area Determination : The web area Aᵥ shall be taken as the overall depth d times the web thickness tᵥ.
b) Design Shear Strength : The design shear strength of webs is φᵥVₙ, where φᵥ = 0.90 and the nominal shear strength Vₙ is determined as follows :
For $\frac{h}{t_w} ≤ 490 \sqrt{k/F_{yw}}$
$$
V_n = 0.0006 F_{yw} A_w
$$
(10.8.57)
For $490 \sqrt{k/F_{yw}} < \frac{h}{t_w} ≤ 615 \sqrt{k/F_{yw}}$
$$
V_n = 0.0006 F_{yw} A_w \frac{490 \sqrt{k/F_{yw}}}{h/t_w}
$$
(10.8.58)
For $\frac{h}{t_w} > 615 \sqrt{k/F_{yw}}$
$$
V_n = A_w \frac{182k}{(h/t_w)^2}
$$
(10.8.59)
The web plate buckling coefficient k is given by
$$
k = 5 + \frac{5}{(a/h)^2}
$$
(10.8.60)
Except that k shall be taken as 5 if a/h exceeds 3.0 or $[260/(h/t_w)]^2$. When stiffeners are not required, k = 5.
Maximum h/tw limits are given below :
For $\frac{a}{h} ≤ 1.5$
$$
\left(\frac{h}{t_w}\right)_{\max} = \frac{5250}{\sqrt{F_{yf}}}
$$
(10.8.61)
For $\frac{a}{h} > 1.5$
$$
\left(\frac{h}{t_w}\right)_{\max} = \frac{96525}{\sqrt{F_{yf}(F_{yf} + 114)}}
$$
(10.8.62)
In unstiffened girders h/tw must be less than 260.
#### 10.8.6.3 Transverse Stiffeners
Transverse stiffeners are not required when $h/t_w ≤ 1100/\sqrt{F_{yw}}$, or when the required shear $V_u$, as determined by structural analysis for the factored loads, is less than or equal to $\phi_v V_n$ for k = 5 given in Sec 10.8.6.2. Transverse stiffeners used to develop the web design shear strength as provided in Sec 10.8.6.2 shall have a moment of inertia about an axis in the web centre for stiffener pairs or about the face in contact with the web plate for single stiffeners, which shall not be less than $(a t_w^3 j)$.
where
$$
j = \frac{2.5}{(a/h)^2} - 2 ≥ 0.5
$$
(10.8.63)
Intermediate stiffeners may be stopped short of the tension flange, provided bearing is not needed to transmit a concentrated load or reaction. The weld by which intermediate stiffeners are attached to the web shall be terminated not less than 4 times nor more than 6 times the web thickness from the nearest toe of the web to flange weld. When single stiffeners are used, they shall be attached to the compression flange, if it consists of a rectangular plate, to resist any uplift tendency due to torsion in the plate. When lateral bracing is attached to a stiffener, or a pair of stiffeners, these, in turn, shall be connected to the compression flange to transmit one per cent of the total flange stress, unless the flange is composed only of angles.
Bolts connecting stiffeners to the girder web shall be spaced not more than 300 mm on centres. If intermittent fillet welds are used, the clear distance between welds shall not be more than 16 times the web thickness nor more than 250 mm.
#### 10.8.6.4 Web-Tapered Member
Design of tapered members shall satisfy the following modified requirements along with the requirements stipulated in Sec 10.8.6.1 through 10.8.6.3.
a) General Requirements
i) It shall possess at least one axis of symmetry which shall be perpendicular to the plane of bending if moments are present.
ii) The flanges shall be of equal and constant area.
iii) The depth shall vary linearly as
$$
d = d_o \left( 1 + \gamma \frac{z}{L} \right)
$$
(10.8.64)
where
$$
\gamma = (d_L - d_o)/d_o ≤ \text{ the smaller of } 0.268 \text{ (} L/d_o \text{) or } 6.0
$$
b) Design Tensile Strength : The design tensile strength of tapered members shall be determined in accordance with the requirements of Sec 10.8.4.1.
c) Design Compressive Strength : The design compressive strength of tapered members shall be determined in accordance with the requirements of Sec 10.8.5.2 using an effective slenderness parameter $λ_{eff}$ computed as follows:
$$
λ_{eff} = \frac{S}{π} \sqrt{\frac{QF_y}{E}}
$$
(10.8.65)
where
* $S$ = $KL/r_{eg}$ for weak axis bending and $K_y L/r_{eg}$ for strong axis bending
* $Q$ = reduction factor
* 1.0, if all elements meet the limiting noncompact width-thickness ratios of Sec 10.8.3.1
* $Q_sQ_a$ , determined in accordance with Sec 10.8.5.6., if any stiffened and/or unstiffened elements exceeded the noncompact limits given in Sec 10.8.3.1.
The smallest area of the tapered member shall be used for Aₛ in Eq (10.8.6).
d) Design Flexural Strength: The design flexural strength of tapered flexural members for the limit state of lateral torsional buckling is φbMₙ, where φb = 0.90 and the nominal strength is
$$
M_n = 1.67 \times 10^{-3} S^2_c F_y
$$
(10.8.66)
$$
F_{by} = \frac{2}{3} \left[ 1.0 - \frac{F_y}{6B_e} \sqrt{F_{sy}^2 + F_{wy}^2} \right] F_y ≤ 0.60F_y
$$
(10.8.67)
unless $F_{by} ≤ F_y / 3$, in which case
$$
F_{by} = B_i \sqrt{F_{sy}^2 + F_{wy}^2}
$$
(10.8.68)
In the above equations,
$$
F_{sy} = \frac{82735}{(h_s L_{d_s}/A_f)}
$$
(10.8.69)
$$
F_{wy} = \frac{1172 \times 10^3}{(h_w L_f/r_{To})^2}
$$
(10.8.70)
where
* $h_s$ = factor equal to 1.0+0.023$γ \sqrt{L_{d_s}/A_f}$
* $h_w$ = factor equal to 1.0+0.00385$γ \sqrt{L/r_{To}}$
* $r_{To}$ = radius of gyration of a section at the smaller end, considering only the compression flange plus ⅓ of the compression web area, taken about an axis in the plane of the web, mm .
B is determined as follows:
i) When the maximum moment M₂ in three adjacent segments of approximately equal unbraced length is located within the central segment and M₁ is the larger moment at one end of the three-segment portion of a member:
$$
B = 1.0 + 0.37\left(1.0 + \frac{M_1}{M_2}\right) + 0.50\gamma\left(1.0 + \frac{M_1}{M_2}\right) \geq 1.0
$$
(10.8.71)
ii) When the largest computed bending stress fb2 occurs at the larger end of two adjacent segments of approximately equal unbraced length and fb1 is the computed bending stress at the smaller end of two-segment portion of a member:
$$
B = 1.0 + 0.58\left(1 + \frac{f_{b1}}{f_{b2}}\right) - 0.707\left(1 + \frac{f_{b1}}{f_{b2}}\right) \geq 1.0
$$
(10.8.72)
iii) When the largest computed bending stress fb2 occurs at the smaller end of two adjacent segments of approximately equal unbraced length and fb1 is the computed bending stress at the larger end of the two-segment portion of a member :
$$
B = 1.0 + 0.55\left(1.0 + \frac{f_{b1}}{f_{b2}}\right) + 2.20\gamma\left(1.0 + \frac{f_{b1}}{f_{b2}}\right) \geq 1.0
$$
(10.8.73)
In the foregoing, $γ = (d_L - d_o)/d_o$ is calculated for the unbraced length that contains the maximum computed bending stress.
iv) When the computed bending stress at the smaller end of a tapered member or segment thereof is equal to zero:
$$
B = \frac{1.75}{1.0 + 0.25\sqrt{\gamma}}
$$
(10.8.74)
where $γ = (d_L - d_o)/d_o$, calculated for the unbraced length adjacent to the point of zero bending stress.
e) Design Shear Strength: The design shear strength of tapered flexural members shall be determined in accordance with Sec 10.8.6.2.
f) Combined Flexure and Axial Force : For tapered members with a single web taper subjected to compression and bending about the major axis, Eq (10.8.103) through 10.8.106 apply, with the following modifications: Pₐ and Pₘₓ shall be determined for the properties of the smaller end, using appropriate effective length factors. Mₐₓ, Mₘₓ, and Mₘₓ shall be determined for the properties of the larger end, Mₓ = 1.67 × 10⁻³ S²\_c F\_y, and Cₘₓ is replaced by C'ₘₓ, determined as follows:
i) When the member is subjected to end moments which cause single curvature bending and approximately equal computed moments at the ends:
$$
C'_{m} = 1.0 + 0.1\left(\frac{P_a}{φ_b P_{cx}}\right) + 0.3\left(\frac{P_a}{φ_b P_{cx}}\right)^2
$$
(10.8.75)
ii) When the computed bending moment at the smaller end of the unbraced length is equal to zero:
$$
C'_{m} = 1.0 + 0.9\left(\frac{P_a}{φ_b P_{cx}}\right) + 0.6\left(\frac{P_a}{φ_b P_{cx}}\right)^2
$$
(10.8.76)
When the effective slenderness parameter λeff ≥ 1.0 and combined stress is checked incrementally along the length, the actual area and the actual section modulus at the section under investigation may be used.
### 10.8.7 Design of Plate Girders
Plate girders shall be distinguished from beams on the basis of the web slenderness ratio hc/tₘ. When this value is greater than 2550 / $\sqrt{F_{yf}}$, the provisions of this section shall apply for design flexural strength, otherwise the requirements of Sec 10.8.6.1(f) shall be applicable.
#### 10.8.7.1 Limitations
Doubly and singly symmetrical single web nonhybrid and hybrid plate girders loaded in the plane of the web shall be designed according to the provisions of this section provided that the following limitations are satisfied.
a) For $\frac{a}{h} ≤ 1.5$
$$
\left(\frac{h}{t_w}\right)_{\max} = \frac{5250}{\sqrt{F_{yf}}}
$$
(10.8.77)
b) For $\frac{a}{h} > 1.5$
$$
\left(\frac{h}{t_w}\right)_{\max} = \frac{96525}{\sqrt{F_{yf}(F_{yf} + 114)}}
$$
(10.8.78)
In unstiffened girders h/tₘ must be less than 260.
For girders covered by this section, the shear strength may be determined by the provisions of Sec 10.8.6.2 if tension field action is not utilized, otherwise the requirements stipulated in Sec 10.8.7.3 shall be applicable.
#### 10.8.7.2 Design Flexural Strength
The design flexural strength of plate girders with slender webs $\left(h_c/t_w > 2550 / \sqrt{F_{yf}}\right)$ shall be φbMₙ, where φb = 0.90 and Mₙ is the lower value obtained according to the limit states of tension flange yield and compression flange buckling.
For tension flange yield
$$
M_n = 10^{-6} S_{st} R_{PG} R_c F_{yd}
$$
(10.8.79)
For compression flange buckling
$$
M_n = 10^{-6} S_w R_{PG} R_c F_{cr}
$$
(10.8.80)
where
$$
R_{PG} = 1 - 0.0005 a_c \left( \frac{h_c}{t_w} \frac{5250}{\sqrt{F_{cr}}} \right) ≤ 1.0
$$
(10.8.81)
$$
R_c = 1.0 - 0.1\left(1 + 3.a_r\right)(0.81 - m) ≤ 1.0 \text{ (for nonhybrid girder, } R_c = 1).
$$
The critical stress Fcr to be used is dependent upon the slenderness parameters λ, λₚ, λᵣ, and C\_PG as follows :
a) For $λ ≤ λ_p$
$$
F_{cr} = F_{yf}
$$
(10.8.82)
b) For $λ_p < λ ≤ λ_r$
$$
F_{cr} = C_b F_{yf} \left[ 1 - \frac{1}{2}\left( \frac{λ - λ_p}{λ_r - λ_p} \right) \right] ≤ F_{yf}
$$
(10.8.83)
c) For $λ > λ_r$
$$
F_{cr} = M_{cr} = 10^{-6} S_{cr}
$$
(10.8.84)
In the foregoing , the slenderness parameter shall be determined for both the limit state of lateral torsional buckling and the limit state of flange local buckling; the slenderness parameter which results in the lowest value of Fcr, governs.
For the limit state of lateral torsional buckling.
$$
λ = \frac{L_b}{r_T}
$$
(10.8.85)
$$
λ_p = \frac{790}{\sqrt{F_{yf}}}
$$
(10.8.86)
$$
λ_r = \frac{1985}{\sqrt{F_{yf}}}
$$
(10.8.87)
$$
C_{PG} = 1.97 \times 10^6 C_b
$$
(10.8.88)
where
$$
C_b = 1.75 + 1.05(M_1/M_2) + 0.3(M_1/M_2)^2 ≤ 2.3
$$
$r_T$ = Radius of gyration of compression flange plus one-sixth the web, mm.
For the limit state of flange local buckling
$$
λ = \frac{b_f}{2t_f}
$$
(10.8.89)
$$
λ_p = \frac{170}{\sqrt{F_{yf}}}
$$
(10.8.90)
$$
λ_r = \frac{395}{\sqrt{F_{yf}}}
$$
(10.8.91)
$$
C_{PG} = 77200
$$
(10.8.92)
$C_b$ = 1
The limit state of flexural web local buckling is not applicable.
#### 10.8.7.3 Design Shear Strength with Tension Field Action
The design shear strength shall be φᵥVₙ, where φᵥ = 0.90 and Vₙ is determined as follows :
$$
V_n = 0.0006F_{yw}A_w
$$
(10.8.93)
b) For $h/t_w > 492 \sqrt{k/F_{yw}}$
$$
V_n = 0.0006 A_w F_{yw} \left[ C_v + \frac{1-C_v}{1.15\sqrt{1+(a/h)^2}} \right]
\tag{10.8.94}
$$
where
$C_v$ = ratio of critical web stress, according to linear buckling theory, to the shear yield stress of web material.
Except for end panels in nonhybrid plate girders, for all panels in hybrid and web tapered plate girders and when $a/h$ exceeds 3.0 or $[260/(h/t_w)]^2$, in these cases, tension field action is not permitted and
$$
V_n = 0.0006 A_w F_{yw} C_v
\tag{10.8.95}
$$
The web plate buckling coefficient $k$ is given as
$$
k = 5 + \frac{5}{(a/h)^2}
\tag{10.8.96}
$$
except that $k$ shall be taken as 5.0 if $a/h$ exceeds 3.0 or $[260/(h/t_w)]^2$. The shear coefficient $C_v$ is determined as follows:
For $492 \sqrt{k/F_{yw}} \leq \frac{h}{t_w} \leq 615 \sqrt{k/F_{yw}}$
$$
C_v = \frac{492 \sqrt{k/F_{yw}}}{h/t_w}
\tag{10.8.97}
$$
For $\frac{h}{t_w} > 615 \sqrt{\frac{k}{F_{yw}}}$
$$
C_v = \frac{303365k}{(h/t_w)^2 F_{yw}}
\tag{10.8.98}
$$
#### 10.8.7.4 Transverse Stiffeners
Transverse stiffeners are not required in plate girders when $h/t_y < 1100/\sqrt{F_{yw}}$ or when the required shear $V_u$, as determined by structural analysis for the factored loads, is less than or equal to $0.0006 A_w F_y C_v$, where $C_v$ is determined for $k = 5$ and $\phi = 0.90$. Stiffeners may be required in certain portions of a plate girder to develop the required shear or to satisfy the limitations given Sec 10.8.7.1.
The moment of inertia $I_{st}$ of a transverse stiffener about an axis in the web centre for stiffener pairs or about the face in contact with the web plate for single stiffeners shall not be less than $at_w^3 j$, where
$$
j = \frac{2.5}{(a/h)^2} - 2 \geq 0.5
\tag{10.8.99}
$$
and the stiffener area $A_{st}$ when designing for tension field action shall not be less than
$$
\frac{F_{yw}}{F_{ysr}} \left[ 0.15Dh t_w (1-C_v) \frac{V_u}{\phi_v V_n} - 18t_w^2 \right] \geq 0
\tag{10.8.100}
$$
where
* $D$ = 1.0 for stiffeners in pairs
* $D$ = 1.8 for single angle stiffeners
* $D$ = 2.4 for single plate stiffeners
$C_v$ and $V_n$ are defined in Sec 10.8.7.3, and $V_u$ is the required shear at the location of the stiffener.
#### 10.8.7.5 Flexure Shear Interaction
Plate girders with webs that depend on tension field action shall satisfy flexure shear interaction criteria. When stiffeners are required and
$$
\frac{0.6V_u}{M_u} \leq \frac{V_u}{M_u} \leq \frac{V_n}{0.75M_n}
\tag{10.8.101}
$$
the following interaction equation shall be satisfied:
$$
\frac{M_u}{M_n} + 0.625 \frac{V_u}{V_n} \leq 1.375 \phi
\tag{10.8.102}
$$
where $M_n$ is the nominal flexural strength of plate girders from Sec 10.8.7.2, $\phi = 0.90$ and $V_n$ is the nominal shear strength from Sec 10.8.7.3, except that $M_n$ may not exceed $\phi M_n$ ($\phi = 0.90$) and $V_n$ may not exceed $\phi V_n$ ($\phi = 0.90$).
### 10.8.8 Members Under Torsion and Combined Forces
This section covers the design of prismatic members subjected to axial force and flexure about one or both axes of symmetry, with or without torsion, and torsion only.
#### 10.8.8.1 Symmetric Members Subjected to Bending and Axial Force
#### a) Doubly and Singly Symmetric Members in Flexure and Tension
The interaction of flexure and tension in symmetric shapes shall be limited by Eq (10.8.103) and (10.8.104).
For $\frac{P_u}{\phi P_n} \geq 0.2$
$$
\frac{P_u}{\phi P_n} + \frac{8}{9} \left( \frac{M_{ux}}{\phi_b M_{nx}} + \frac{M_{uy}}{\phi_b M_{ny}} \right) \leq 1.0
\tag{10.8.103}
$$
For $\frac{P_u}{\phi P_n} < 0.2$
$$
\frac{P_u}{2\phi P_n} + \left[ \frac{M_{ux}}{\phi_b M_{nx}} + \frac{M_{uy}}{\phi_b M_{ny}} \right] \leq 1.0
\tag{10.8.104}
$$
where
* $\phi = \phi_t$ = resistance factor for tension, 0.90
* $\phi_b$ = resistance factor for flexure, 0.90.
Second order effects may be considered in the determination of $M_u$ for use in Eq (10.8.103) and (10.8.104).
#### b) Doubly and Singly Symmetric Members in Flexure and Compression
The interaction of flexure and compression in symmetric shapes shall be limited by Eq (10.8.103) and (10.8.104), by substituting $\phi$ with $\phi_c$, where $\phi_c$ = resistance factor for compression = 0.85.
##### i) Determination of $M_u$
In elastic design, $M_u$ shall be determined from a second order elastic analysis using factored loads. In plastic design, $M_u$ shall be determined from a plastic analysis. In structures designed on the basis of elastic first order analysis the following procedure for the determination of $M_u$ shall be used.
$$
M_u = B_1 M_{ux} + B_2 M_{uy}
\tag{10.8.105}
$$
where
$$
B_1 = \frac{\phi_c}{1 - (P_u/P_{ex})}
\tag{10.8.106}
$$
$P_{ex} = 10^3 A_g F_y / \lambda_c^2$, where $\lambda_c$ is given by Eq (10.8.9) with $K \leq 1.0$ in the plane of bending.
$C_{mx}$ = a coefficient whose value shall be taken as follows:
**A. For restrained compression members in frames braced against joint translation and not subjected to transverse loading between their supports in the plane of bending:**
$$
C_{mx} = 0.6 - 0.4(M_1/M_2)
\tag{10.8.107}
$$
where $M_1/M_2$ is the ratio of the smaller to larger moments at the ends of that portion of the member unbraced in the plane of bending under consideration. $M_1/M_2$ is positive when the member is bent in reverse curvature, negative when bent in single curvature.
**B. For compression members in frames braced against joint translation in the plane of loading and subjected to transverse loading between their supports, the value of $C_{mx}$ can be determined by rational analysis. In lieu of such analysis, the following values shall be used:**
* for members whose ends are restrained $C_{mx} = 0.85$
* for members whose ends are unrestrained $C_{mx} = 1.0$
$$
B_2 = \frac{\phi_c}{1 - (P_u/P_{ey})}
\tag{10.8.108}
$$
$$
C_{my} = 0.85
\tag{10.8.109}
$$
In which
* $H$ = sum of all storey horizontal forces producing $\Delta_i$, kN.
* $P_{ey} = 10^3 A_g F_y / \lambda_c^2$, where $\lambda_c$ is the slenderness parameter given by Eq (10.8.9), in which the effective length factor $K$ in the plane of bending shall be determined in accordance with Sec 10.5.2.2 but shall not be less than unity.
* $L$ = storey height, mm.
##### ii) Determination of $M_n$
In the use of Eq (10.8.103) and (10.8.104), $M_n$ shall be determined in accordance with Sec 10.8.6.1. The actual value of $C_b$ from Sec 10.8.6.1(c) shall be used, provided that the maximum moment $M_{max}$ occurs at the end of the member or at the end of an unbraced segment of a member. When the maximum moment occurs between the ends, $M_n$ shall be determined with $C_b = 1.0$. When Eq (10.8.105) is used for determining $M_u$ the maximum moment for a braced member bent about the strong axis and braced only at its ends will occur at an end whenever the calculated value of $B_1$ is equal to or less than unity.
#### 10.8.8.2 Unsymmetric Members and Members Under Torsion and Combined Torsion, Flexure and/or Axial Force
The design strength $\phi F_n$ of the member shall equal or exceed the required strength expressed in terms of the normal stress $f_n$ or the shear stress $f_v$, determined by elastic analysis for the factored loads.
a) For the limit state of yielding under normal stress:
$$
F_n \leq 0.6 F_y
\tag{10.8.110}
$$
$\phi = 0.90$
b) For the limit state of yielding under shear stress:
$$
F_n \leq 0.6 F_y
\tag{10.8.111}
$$
$\phi = 0.90$
c) For the limit state of buckling:
$$
f_n + f_v \leq \phi_c F_{cr}
\tag{10.8.112}
$$
as applicable
where
$\phi_c = 0.85$ and $F_{cr}$ shall be determined from Eq (10.8.11) or (10.8.12) as applicable.
Some constrained local yielding is permitted in areas adjacent to areas which remain elastic.
#### 10.8.8.3 Alternative Interaction Equations for Members under Combined Stress
For biaxially loaded I-shaped members used in braced frames only, the following interaction equations may be used in lieu of Eq (10.8.103) and (10.8.104).
$$
\frac{P_u}{\phi_c P_n} + \frac{M_{ux}}{\phi_b M_{px}} + \frac{M_{uy}}{\phi_b M_{py}} \leq 1.0
\tag{10.8.113}
$$
$$
\frac{P_u}{\phi_c P_n} \gamma + \frac{M_{ux}}{\phi_b M_{nx}} + \frac{M_{uy}}{\phi_b M_{ny}} \leq 1.0
\tag{10.8.114}
$$
For $0.5 < b/d \leq 1.0$:
$$
\gamma = 1.6 - \frac{P_u}{P_y} \frac{2 \ln(P_y/P_u)}
\tag{10.8.115}
$$
For $b/d \geq 0.3$:
$$
\gamma = 0.44 + \frac{F_u}{d} \frac{10}{(b/d)}
\tag{10.8.116}
$$
For $b/d < 0.3$: $\gamma = 1.0$
In the above,
$$
M_{px} = 1.2 M_{px} [1 - (P_u/P_y)]^2 \leq M_{yx}
\tag{10.8.117}
$$
$$
M_{py} = 1.2 M_{py} [1 - (P_u/P_y)^2] \leq M_{yy}
\tag{10.8.118}
$$
$$
M_{nx} = \frac{P_u}{P_y} M_{px}
\tag{10.8.119}
$$
$$
M_{ny} = M_{ny} \left( 1 - \frac{P_u}{P_y} \right) \leq \frac{P_u}{P_y}
\tag{10.8.120}
$$
### 10.8.9 Design of Trusses
#### 10.8.9.1 General
Trusses are composed of individual members connected by welds, rivets or bolts.
#### 10.8.9.2 Purlins
Requirements of this section shall be in accordance with the requirements of Sec 10.7.9.2.
#### 10.8.9.3 Design of Members
a) Compression Members: All members under compressive forces shall be designed to satisfy the requirements of Sec 10.8.5.
b) Tension Members: All members under tensile forces shall be designed to satisfy the requirements of Sec 10.8.4.
#### 10.8.9.4 Joints and Connections
Design of joints and connections in trusses shall satisfy the requirements of Sec 10.9.
#### 10.8.9.5 Deflection and Camber
a) Deflection: Deflection due to service live load plus impact, if any, shall be limited so as not to impair serviceability.
b) Camber: Trusses shall be provided with camber in accordance with Sec 10.10.1.
#### 10.8.9.6 Bracing
Trusses shall be adequately braced against instability.
### 10.8.10 Design of Composite Members
This section specifies the requirements for composite columns made of rolled or built-up structural steel shapes, pipe or tubing and structural concrete acting together and for steel beams supporting a reinforced concrete slab so interconnected that the beams and the slab act together to resist bending. Simple and continuous composite beams with shear connectors and concrete encased beams, constructed with or without temporary shores, are included.
#### 10.8.10.1 Design Assumptions
a) Force Determination: In determining forces in members and connections of a structure that includes composite columns and beams, consideration must be given to the effective sections at the time each increment of load is applied.
b) Elastic Analysis: For an elastic analysis of continuous composite beams without haunched ends, it is acceptable to assume that the stiffness of a beam is uniform throughout the beam length and may be computed using the moment of inertia of the composite transformed section in the positive moment region.
c) Plastic Analysis: When plastic analysis is used, the strength of flexural composite members shall be determined from plastic stress distributions as specified in Sec 10.8.10.3.
d) Plastic Stress Distribution for Positive Moment: If the slab in the positive moment region is connected to the steel beam with shear connectors, a concrete stress of $0.85 f_c'$ may be assumed uniformly distributed throughout the effective compression zone. Concrete tensile strength shall be neglected. A uniformly distributed steel stress of $F_y$ shall be assumed throughout the tension zone and throughout the compression zone in the structural steel section. The net tensile force in the steel section shall be equal to the compressive force in the concrete slab.
e) Plastic Stress Distribution for Negative Moment: If the slab in the negative moment region is connected to the steel beam with shear connectors, a tensile stress of $F_{yr}$ shall be assumed in all adequately developed longitudinal reinforcing bars within the effective width of the concrete slab. Concrete tensile strength shall be neglected. A uniformly distributed steel stress of $F_y$ shall be assumed throughout the tension zone and throughout the compression zone in the structural steel section. The net compressive force in the steel section shall be equal to the total tensile force in the reinforcing steel.
f) Elastic Stress Distribution: When a determination of elastic stress distribution is required, strains in steel and concrete shall be assumed to be directly proportional to the distance from the neutral axis. The stress shall equal strain times $E$ or $E_c$. Concrete tensile strength shall be neglected. Maximum stress in the steel shall not exceed $F_y$. Maximum compressive stress in the concrete shall not exceed $0.85 f_c'$. In composite hybrid beams, the maximum stress in the steel flange shall not exceed $F_{yf}$ but the strain in the web may exceed the yield strain and the stress shall be taken as $F_y$ at such locations.
g) Fully Composite Beam: Shear connectors are to be provided in sufficient numbers to develop the maximum flexural strength of the composite beam. For elastic stress distribution it may be assumed that no slip occurs.
h) Partially Composite Beam: The shear strength of shear connectors governs the flexural strength of the partially composite beam. Elastic computations such as those for deflections and vibrations should include the effect of slip.
i) Concrete Encased Beam: A beam totally encased in concrete cast integrally with the slab may be assumed to be interconnected to the concrete by natural bond, without additional anchorage, provided that: (1) concrete cover over beam sides and soffit is at least 50 mm; (2) the top of the beam is at least 40 mm below the top and 50 mm above the bottom of the slab; and (3) concrete encasement contains adequate mesh or other reinforcing steel to prevent spalling of concrete.
j) Composite Column: A steel column fabricated from rolled or built-up steel shapes and encased in structural concrete or fabricated from steel pipe or tubing filled with structural concrete.
#### 10.8.10.2 Compression Members
#### a) Limitations
To qualify as a composite column, the following limitations shall be met.
i) The cross-sectional area of the steel shape, pipe or tubing shall comprise at least 4% of the total composite cross-section.
ii) Concrete encasement of a steel core shall be reinforced with longitudinal load carrying bars, longitudinal bars to restrain concrete and lateral ties. Longitudinal load carrying bars shall be continuous at framed levels; longitudinal restraining bars may be interrupted at framed levels. The spacing of ties shall be not greater than $\frac{1}{4}$ of the least dimension of the composite cross-section.
The cross-sectional area of the transverse and longitudinal reinforcement shall be at least 0.0178 mm² per mm of bar spacing. The encasement shall provide at least 40 mm of clear cover outside of both transverse and longitudinal reinforcement.
iii) Concrete shall have a specified compressive strength $f_c'$ of not less than 20 N/mm² nor more than 55 N/mm².
iv) The specified minimum yield stress of structural steel and reinforcing bars used in calculating the strength of a composite column shall not exceed 380 N/mm².
v) The minimum wall thickness of structural steel pipe or tubing filled with concrete shall be equal to $b \sqrt{F_y/3E}$ for each face of width $b$ in rectangular sections and $D \sqrt{F_y/8E}$ for circular sections of outside diameter $D$.
#### b) Design Strength
The design strength of axially loaded composite columns is $\phi_c P_n$, where $\phi_c = 0.85$ and the nominal axial compressive strength $P_n$ shall be determined from Eq (10.8.6) through (10.8.9) with the following modifications:
i) $A_s$ = gross area of steel shape, pipe or tubing, mm² (replaces $A_g$)
$r_m$ = radius of gyration of the steel shape, pipe or tubing except that for steel shapes it shall not be less than 0.3 times the overall thickness of composite cross-section in the plane of buckling, mm (replaces $r$)
ii) Replace $F_y$ with modified yield stress $F_{ym}$ from Eq (10.8.121) and replace $E$ with modified modulus of elasticity $E_m$ from Eq (10.8.122).
$$
F_{ym} = F_y + c_1 F_{yr} (A_r/A_s) + c_2 f_c' (A_c/A_s)
\tag{10.8.121}
$$
$$
E_m = E + c_3 E_c (A_c/A_s)
\tag{10.8.122}
$$
where
$c_1, c_2, c_3$ = numerical coefficients. For concrete-filled pipe and tubing $c_1 = 1.00$, $c_2 = 0.85$, and $c_3 = 0.40$. For concrete encased shapes $c_1 = 0.70$, $c_2 = 0.60$ and $c_3 = 0.20$.
#### c) Columns with Multiple Steel Shapes
If the composite cross-section includes two or more steel shapes, the shapes must be interconnected with lacing, tie plates or batten plates to prevent buckling of individual shapes before hardening of concrete.
#### d) Load Transfer
The portion of the design strength of axially loaded composite columns resisted by concrete shall be developed by direct bearing at connections. When the supporting concrete area is wider than the loaded area on one or more sides and otherwise restrained against lateral expansion on the remaining sides, the maximum design strength of concrete shall be $1.7 \phi_c f_c' A_p$, where $\phi_c = 0.60$ is the resistance factor in bearing on concrete and $A_p$ is the loaded area.
#### 10.8.10.3 Flexural Members
#### a) Effective Width
The portion of the effective width of the concrete slab on each side of the beam centre line shall not exceed:
i) One-eighth of beam span, centre to centre of supports;
ii) One-half the distance to the centre line of the adjacent beam; or
iii) The distance from the beam centre line to the edge of the slab.
#### b) Strength of Beams with Shear Connectors
The positive design flexural strength $\phi_b M_n$ shall be determined as follows:
i) For $h_e/t_y \leq 1680/\sqrt{F_y}$
$\phi_b = 0.85$; $M_n$ shall be determined from plastic stress distribution on the composite section.
ii) For $h_e/t_y > 1680/\sqrt{F_y}$
$\phi_b = 0.90$; $M_n$ shall be determined from the superposition of elastic stresses, considering the effects of shoring.
The negative design flexural strength $\phi_b M_n$ shall be determined for the steel section alone, in accordance with the requirements of Sec 10.8.6.
Alternatively, the negative design flexural strength $\phi_b M_n$ may be computed with $\phi_b = 0.85$ and $M_n$ determined from the plastic stress distribution on the composite section, provided that:
i) Steel beam is an adequately braced compact section, as defined in Sec 10.8.3.1.
ii) Shear connectors connect the slab to the steel beam in the negative moment region.
iii) Reinforcing steel parallel to the steel beam, within the effective width of the slab, is properly developed.
#### c) Strength of Concrete Encased Beams
The design flexural strength $\phi_b M_n$ shall be computed with $\phi_b = 0.90$ and $M_n$ determined from the superposition of elastic stresses, considering the effects of shoring.
Alternatively, the design flexural strength $\phi_b M_n$ may be computed with $\phi_b = 0.90$ and $M_n$ determined from the plastic stress distribution on the steel section alone.
#### d) Strength During Construction
When temporary shores are not used during construction, the steel section alone shall have adequate strength to support all loads applied prior to the concrete attaining 75% of its specified strength $f_c'$. The design flexural strength of the steel section shall be determined in accordance with the requirements of Sec 10.8.6.1.
#### e) Formed Steel Deck
i) The design flexural strength $\phi_b M_n$ of composite construction consisting of concrete slabs on formed steel deck connected to steel beams shall be determined by the applicable portions of (b) above with the following modifications.
This section is applicable to decks with nominal rib height not greater than 75 mm. The average width of concrete rib or haunch $w_r$ shall be not less than 50 mm, but shall not be taken in calculations as more than the minimum clear width near the top of the steel deck. See (iii) below for additional restrictions.
The concrete slab shall be connected to the steel beam with welded stud shear connectors, conforming to AWS D1.1, 20 mm or less in diameter. Studs shall be welded either through the deck or directly to the steel beam. Stud shear connectors, after installation, shall extend not less than 40 mm above the top of the steel deck.
The slab thickness above the steel deck shall be not less than 50 mm.
ii) Deck Ribs Oriented Perpendicular to Steel Beam: Concrete below the top of the steel deck shall be neglected in determining section properties and in calculating $A_c$ for deck ribs oriented perpendicular to the steel beams.
The spacing of stud shear connectors along the length of a supporting beam shall not exceed 800 mm.
The nominal strength of a stud shear connector shall be the value stipulated in Sec 10.8.10.5 multiplied by the following reduction factor:
$$
\frac{0.85(w_r/h_r)[(H_s/h_r) - 1.0]}{N_s} \leq 1.0
\tag{10.8.123}
$$
To resist uplift, steel deck shall be anchored to all supporting members at a spacing not to exceed 400 mm. Such anchorage may be provided by stud connectors, a combination of stud connectors and arc spot welds or other devices specified by the designer.
iii) Deck Ribs Oriented Parallel to Steel Beam: Concrete below the top of steel deck may be included in determining section properties and shall be included in calculating $A_c$ for Sec 10.8.10.5. Steel deck ribs over supporting beams may be split longitudinally and separated to form a concrete haunch.
When the nominal depth of steel deck is 40 mm or greater, the average width $w_r$ of the supported haunch or rib shall be not less than 50 mm for the first stud in the transverse row plus 4 stud diameters for each additional stud.
The nominal strength of a stud shear connector shall be the value stipulated in Sec 10.8.10.5 except that when $w_r/h_r$ is less than 1.5, the value from Sec 10.8.10.5 shall be multiplied by the following reduction factor:
$$
0.6(w_r/h_r)[H_s/h_r - 1.0] \leq 1.0
\tag{10.8.124}
$$
#### f) Design Shear Strength
The design shear strength of composite beam shall be determined by the shear strength of the steel web, in accordance with the requirements of Sec 10.8.6.2.
#### 10.8.10.4 Combined Compression and Flexure
The interaction of axial compression and flexure in the plane of symmetry on composite members shall be limited by Eq (10.8.103) through (10.8.109) with the following modifications:
$M_n$ = nominal flexural strength determined from plastic stress distribution on the composite cross-section except as provided below, kKNm
$P_e$ = $A_s F_{ym} / \lambda_c^2$, elastic buckling load, kN.
$\phi_b$ = resistance factor for flexure from Sec 10.8.10.3.
$\phi_c$ = 0.85.
$\lambda_c$ = column slenderness parameter defined by Eq (10.8.9) as modified in Sec 10.8.10.2(b).
When the axial term in Eq (10.8.103) and (10.8.104) is less than 0.3, the nominal flexural strength $M_n$ shall be determined by straight line transition between the nominal flexural strength determined from the plastic distribution on the composite cross-sections at $(P_u/\phi_c P_n) = 0.3$ and the flexural strength at $P_u = 0$ as determined from Sec 10.8.10.3. If shear connectors are required at $P_u = 0$, they shall be provided whenever $(P_u/\phi_c P_n)$ is less than 0.3.
#### 10.8.10.5 Shear Connectors
This section covers the design of stud and channel shear connectors.
#### a) Material
Shear connectors shall be headed steel studs not less than four stud diameters in length after installation, or hot rolled steel channels. The stud connectors shall conform to the requirements of Sec 10.3.5. The channel connectors shall conform to the requirements of Sec 10.3.1. Shear connectors shall be embedded in concrete slabs made with ASTM C33 aggregate.
#### b) Horizontal Shear Force
Except for concrete encased beams as defined in Sec 10.8.10.1, the entire horizontal shear at the interface between the steel beam and the concrete slab shall be assumed to be transferred by shear connectors. For composite action with concrete subject to flexural compression, the total horizontal shear force, kN, between the point of maximum positive moment and the point of zero moment shall be taken as the smallest of:
i) $0.85 \times 10^{-3} f_c' A_c$
ii) $10^{-3} A_s F_y$
iii) $\sum Q_n$
where
$\sum Q_n$ = sum of nominal strengths of shear connectors between the point of maximum positive moment and the point of zero moment, kN.
In continuous composite beams where longitudinal reinforcing steel in the negative moment regions is considered to act compositely with the steel beam, the total horizontal shear force between the point of maximum negative moment and the point of zero moment shall be taken as the smaller of $10^{-3} A_r F_{yr}$ and $\sum Q_n$;
where
$A_r$ = area of adequately developed longitudinal reinforcing steel within the effective width of the concrete slab, mm².
$F_{yr}$ = minimum specified yield stress of the reinforcing steel, N/mm².
#### c) Strength of Stud Shear Connectors
The nominal strength of one stud shear connector embedded in a solid concrete slab is
$$
Q_n = 0.5 \times 10^{-3} A_{sc} \sqrt{f_c' E_c} \leq 10^{-3} A_{sc} F_u
\tag{10.8.125}
$$
For a stud shear connector embedded in a slab on a formed steel deck, see Sec 10.8.10.3 for reduction factors given by Eq (10.8.123) and (10.8.124) as applicable. The reduction factors should be applied only to $0.5 \times 10^{-3} A_{sc} \sqrt{f_c' E_c}$ term in Eq (10.8.125).
#### d) Strength of Channel Shear Connectors
The nominal strength of one channel shear connector embedded in a solid concrete slab is
$$
Q_n = 0.3 \times 10^{-3} (t_f + 0.5 t_w) L_c \sqrt{f_c' E_c}
\tag{10.8.126}
$$
#### e) Required Number of Shear Connectors
The number of shear connectors required between the section of maximum bending moment, positive or negative, and the adjacent section of zero moment shall be equal to the horizontal shear force as determined from (b) above divided by the nominal strength of one shear connector as determined from (c) or (d) above.
#### f) Shear Connector Placement and Spacing
Shear connectors on each side of the point of maximum bending moment, positive or negative, shall be distributed uniformly between that point and the adjacent points of zero moment. However, the number of shear connectors placed between any concentrated load and the nearest point of zero moment shall be sufficient to develop the maximum moment required at the concentrated load point.
Except for connectors installed in the ribs of formed steel deck, shear connectors shall have at least 25 mm of lateral concrete cover. Unless located over the web, the diameter of studs shall not be greater than 2.5 times the thickness of the flange to which they are welded. The minimum centre to centre spacing of stud connectors shall be 6 diameters along the longitudinal axis of the supporting composite beam and 4 diameters transverse to the longitudinal axis of the supporting composite beam, except that within the ribs of formed steel decks the centre to centre spacing may be as small as 4 diameters in any direction. The maximum centre to centre spacing of shear connectors shall not exceed 8 times the total slab thickness.
### 10.8.11 Special Design Considerations
This section provides the design consideration related to special situations such as concentrated loads, ponding and torsion.
#### 10.8.11.1 Webs and Flanges with Concentrated Forces
#### a) Design Basis
Members with concentrated loads applied normal to one flange and symmetric to the web shall have a flange and web design strength sufficient to satisfy the local flange bending, web yielding, web crippling and sidesway web buckling criteria of (b) through (e) below. Members with concentrated loads applied to both flanges shall have a web design strength sufficient to satisfy the web yielding, web crippling and column web buckling criteria of (c), (d) and (f) below.
Where pairs of stiffeners are provided on opposite sides of the web at concentrated loads and extend at least half the depth of the member, (b) and (c) below need not be checked.
For column webs subjected to high shears, the provisions of (g) below shall apply.
For bearing stiffeners, the provisions of (h) below shall apply.
b) Local Flange Bending : The flange design strength in bending due to a tensile load shall be $\phi R_n$, kN.
where
$$
\phi = 0.90
$$
$$
R_n = 0.00625 t_f^2 F_{yf}
\tag{10.8.127}
$$
If the length of loading measured across the member flange is less than 0.15*b*, where *b* is the member flange width, Eq (10.8.127) need not be checked.
c) Local Web Yielding : The design strength of the web at the toe of the fillet under concentrated loads shall be $\phi R_n$, where $\phi = 1.0$ and $R_n$ is determined as follows :
i) When the force to be resisted is a concentrated load producing tension or compression, applied at a distance from the member end that is greater than the depth of the member,
$$
R_n = \left( \frac{5k + N}{1000} \right) F_{yw} t_w
\tag{10.8.128}
$$
ii) When the force to be resisted is a concentrated load applied at or near the end of member,
$$
R_n = \left( \frac{2.5k + N}{1000} \right) F_{yw} t_w
\tag{10.8.129}
$$
In the above, *k* = distance from outer face of flange to web toe of fillet, mm.
d) Web Crippling: For unstiffened portions of webs of members under concentrated loads, the design compressive strength shall be $\phi R_n$, where $\phi = 0.75$ and nominal strength $R_n$ is determined as follows :
i) When the concentrated load is applied at a distance not less than *d*/2 from the end of the member :
$$
R_n = 0.354 t_w^2 \left[ 1 + 3 \left( \frac{N}{d} \right) \left( \frac{t_w}{t_f} \right)^{1.5} \right] \sqrt{F_{yw} t_f / t_w}
\tag{10.8.130}
$$
ii) When the concentrated load is applied less than a distance *d*/2 from the end of the member :
$$
R_n = 0.179 t_w^2 \left[ 1 + 3 \left( \frac{N}{d} \right) \left( \frac{t_w}{t_f} \right)^{1.5} \right] \sqrt{F_{yw} t_f / t_w}
\tag{10.8.131}
$$
If stiffeners are provided and extend at least one-half the web depth, Eq (10.8.130) and (10.8.131) need not be checked.
e) Sidesway Web Buckling : For webs of members with flanges not restrained against relative movement by stiffeners or lateral bracing and subject to concentrated compressive loads, the design compressive strength shall be $\phi R_n$, where $\phi = 0.85$ and the nominal strength $R_n$ is determined as follows :
i) If the loaded flange is restrained against rotation and $(d_c/t_w)/(l/b_f)$ is less than 2.3 :
$$
R_n = \frac{83 t_w^3}{h} \left[ 1 + 0.4 \left( \frac{d_c/t_w}{l/b_f} \right)^3 \right]
\tag{10.8.132}
$$
ii) If the loaded flange is not restrained against rotation and $(d_c/t_w)/(l/b_f)$ is less than 1.7 :
$$
R_n = \frac{83 t_w^3}{h} \left[ 0.4 \left( \frac{d_c/t_w}{l/b_f} \right)^3 \right]
\tag{10.8.133}
$$
where
$d_c = d - 2k$ = web depth clear of fillets, mm.
Eq (10.8.132) and (10.8.133) need not be checked provided $(d_c/t_w)/(l/b_f)$ exceeds 2.3 or 1.7 respectively, or for webs subject to distributed load.
If a concentrated load is located at a point where the web flexural stress due to factored loads is below yielding, 165 shall be used in lieu of 83 in Eq (10.8.132) and (10.8.133).
f) Compression Buckling of the Web : For unstiffened portions of webs of members under concentrated loads to both flanges, the design compressive strength shall be $\phi R_n$, where
$$
\phi = 0.90
$$
$$
R_n = \frac{10.76 t_w^3 \sqrt{F_{yw}}}{d_c}
\tag{10.8.134}
$$
$R_n$ may be exceeded provided that a transverse stiffener or pair of stiffeners is attached to the web to satisfy Sec 10.8.6.3.
g) Compression Members with Web Panels Subjected to High Shears : For compression members subjected to high shear stress in the web, the design web shear strength shall be $\phi R_v$, where $\phi = 0.90$ and $R_v$ is determined as follows :
i) For $P_u \leq 0.75 P_n$:
$$
R_v = 0.0007 F_y d_c t_w
\tag{10.8.135}
$$
ii) For $P_u > 0.75 P_n$:
$$
R_v = 0.0007 F_y d_c t_w \left[ 1.9 - 1.2 (P_u/P_n) \right]
\tag{10.8.136}
$$
h) Stiffener Requirements for Concentrated Loads : When required, stiffeners shall be placed in pairs at unframed ends of beams and girders. They shall be placed in pairs at points of concentrated load on the interior of beams, girders or column if the load exceeds the nominal strength $\phi R_n$ as determined from (b) through (f) above as applicable.
If the concentrated load, tension or compression exceeds the criteria for $\phi R_n$ of (b) or (c) above respectively, stiffeners need not be extended more than one-half the depth of the web, except as follows :
If concentrated compressive loads are applied to the members and if the load exceeds the compressive strength of the web $\phi R_n$ given in (d) or (f) above, the stiffener shall be designed as axially compressed members (columns) in accordance with the requirements of Sec 10.8.5.2 with an effective length equal to 0.75*h*, a cross-section composed of two stiffeners and a strip of the web having a width of $25t_w$ at interior stiffeners and $12t_w$ at the ends of members.
When the load normal to the flange is tensile, the stiffeners shall be welded to the loaded flange. When the load normal to the flange is compressive, the stiffeners shall either bear on or be welded to the loaded flange.
#### 10.8.11.2 Ponding
The roof system shall be investigated for ponding in accordance with the provisions of Sec 10.7.11.2.
#### 10.8.11.3 Torsion
For limiting values of normal and shear stresses, due to torsion and other loading, the provisions of Sec 10.8.8.2 shall apply. Some constrained local yielding may be permitted.
### 10.8.12 Seismic Design Provisions
#### 10.8.12.1 Scope
This section specifies special seismic design provisions for the design and construction of structural steel members and connections in buildings for which the design forces resulting from earthquake motions have been determined on the basis of energy dissipation in the nonlinear range of response. These special seismic requirements are to be applied in conjunction with the Load Factor Design method. The special seismic design provisions apply only to buildings in Zone 3 and to buildings in Zone 2 having an importance factor *I* greater than 1.0.
#### 10.8.12.2 Seismic Zoning
Seismic zoning provisions shall be as stipulated in Chapter 2, Loads.
#### 10.8.12.3 Loads and Load Combinations
The design loads shall be the minimum factored loads and their combinations specified in Chapter 2, Loads.
#### 10.8.12.4 Storey Drift and Building Separations
Storey drift shall be calculated using the appropriate effects consistent with the structural system and the method of analysis. Limits on storey drift shall be in accordance with Sec 1.5.6, Chapter 1, General Design Requirements.
#### 10.8.12.5 Materials
Steel used in seismic force resisting systems shall be as listed in Sec 10.3.1. For buildings over one storey in height, the steel used in seismic resisting systems described in Sec 10.8.14.7, 10.8.14.8 and 10.8.14.9 shall be limited to the following ASTM Specifications : A36, A441, A500 (Grades B and C), A501, A572 (Grades 42 and 50), and A588. For base plates, ASTM A283 Grade D can be used in lieu of the other plate materials listed above.
#### 10.8.12.6 Column Requirements
a) Columns in earthquake resisting frames shall comply with the requirements of Sec 10.8.5 and 10.8.8. When $P_u/\phi P_n > 0.5$ column axial design strength shall be limited by the following requirements.
i) Axial compression loads :
$$
1.2 P_D + 0.5 P_L + 1.0 P_{E'} \leq \phi P_n
\tag{10.8.137}
$$
**Exception :**
The load factor on *L* used to determine $P_L$ in Eq (10.8.137) shall be equal to 1.0 for garages, areas occupied as places of public assembly and all areas where the live load is greater than 5.0 kN/m².
ii) Axial tension loads :
$$
0.9 P_D + 1.0 P_{E'} \leq \phi P_n
\tag{10.8.138}
$$
iii) The required axial strengths in Eq (10.8.137) and (10.8.138) need not exceed either of the following:
A. The maximum loads that can be transferred to the column, considering 1.25 times the design strengths of the connecting beam or brace elements of the structure.
B. The limit as determined by the foundation capacity to resist overturning uplift.
b) Column Splices : Column splices shall have sufficient strength to develop the column axial loads given in (i), (ii) and (iii) above as well as the load combinations specified in Sec 2.7.5.2 of Chapter 2, Loads.
i) In column splices using either complete or partial penetration welded joints, changes in thickness and width of flanges and webs are permitted without providing bevelled transitions.
ii) Splices using partial penetration welded joints shall not be within 900 mm of the beam to column connection. Column splices that are subjected to net tension forces shall comply with the more critical of the following:
A. The lesser design strength of $\phi_w F_w A_w$ or $\phi_w F_{BM} A_w$ (see Sec 10.9.2.4) for partial penetration welded joints shall be at least 150 per cent of the required strength.
B. The design strength of welds shall not be less than $0.5 F_{yc} A_f$ where $F_{yc}$ is the yield strength of the column material and $A_f$ is the flange area of the smaller column connected.
#### 10.8.12.7 Requirements for Ordinary Moment Frames (OMF)
a) Design Strength : Ordinary moment frames (OMF), where permitted according to the provisions of this Code, shall have the design strength to resist the load combinations specified in Sec 2.7.5.2 of Chapter 2, Loads. The design strength of such members shall be determined using the LFD method.
b) Joint Requirements : All beam to column connections in OMF which resist earthquake forces shall meet one of the following requirements :
i) FR (fully restrained) connections conforming with Sec 10.8.12.8(b).
ii) FR connections with design strengths of the connections meeting the requirements of (a) above using the load combinations 7 and 8 specified in Sec 2.7.5.2 of Chapter 2, Loads.
iii) Either FR or PR (partially restrained) connections are permitted provided :
A. The design strengths of the members and connections meet the requirements of (a) above.
B. The connections have been demonstrated by cyclic tests to have adequate rotation capacity at a storey drift calculated at a horizontal load of E′.
C. The additional drift due to PR connections shall be considered in design.
FR and PR connections are described in detail in Sec 10.4.
#### 10.8.12.8 Requirements for Special Moment Frames (SMF)
a) Scope : Special moment frames (SMF), shall be used when required by the provisions of this Code. For buildings in Seismic Zone 2 having an importance factor I greater than 1.0, only the requirements of (b), (c), (g), and (h) below shall be applicable.
b) Beam to Column Joints
i) The required flexural strength $M_u$ of each beam to column joint shall be the lesser of the following quantities :
A. The plastic bending moment $M_p$ of the beam.
B. The moment resulting from the panel zone nominal shear strength $V_n$ as determined using Eq (10.8.139).
The joint need not develop either of the strengths defined above if it can be shown that under an amplified frame deformation of E′/E times that produced by load combinations 5 and 6 specified in Sec 2.7.5.2 of Chapter 2, Loads, the design strength of the members at the connection are adequate to support the vertical loads, and the required lateral force resistance is provided by other means.
ii) The required shear strength $V_u$ of a beam to column joint shall be determined using the load combination $1.2D + 0.5L$ plus the shear resulting from $M_u$, as defined in (i) above, on at least one end of the beam. The required shear strength need not exceed the shear resulting from the load combination 7 specified in Sec 2.7.5.2 of Chapter 2, Loads.
iii) The design strength $\phi R_n$ of a beam to column joint can be considered adequate to develop the required flexural strength $M_u$ of the beam if it conforms to the following :
A. The beam flanges are welded to the column using complete penetration welded joints.
B. The beam web joint shall have a design shear strength $\phi V_n$ greater than the required shear $V_u$ and conform to either :
1. Where the nominal flexural strength of the beam $M_n$ considering only the flanges is greater than 70 per cent of the nominal flexural strength of the entire beam section i.e.,
$$
\left[ 10^{-6} b_f t_f (d - t_f) F_{yf} \geq 0.7 M_p \right],
$$
the web joint may be made by means of welding or slip-critical high strength bolting.
2. Where a slip-critical high strength bolted joint in a beam does not meet the flexural criteria in (i) above the required strength of added web welding shall be at least 20 per cent of the nominal flexural strength of the beam web. The required beam shear strength shall be developed by further welding or by slip-critical high strength bolting.
iv) Alternate joint configurations : Joint configurations utilizing welds or high strength bolts, but not conforming to (iii) above, may be used if shown by test or calculations to meet the criteria of (i) above. Where conformance is shown by calculation, the design strength of the joint shall be 125 per cent of the design strengths of the connecting elements.
c) Panel Zone of Beam to Column Connections (Beam Web Parallel to Column Web)
i) Shear strength : The required shear strength $V_u$ of the panel zone shall be based on the beam bending moments determined from the load combinations 5 and 6 specified in Sec 2.7.5.2 of Chapter 2, Loads. $V_u$ need not exceed that determined from $0.9 \sum \phi_b M_p$ of the beams framing into the column flanges at the connection. The design shear strength $\phi_v V_n$ of the panel zone shall be determined by the following formula :
$$
\phi_v V_n = 0.55 \times 10^{-3} \phi_v F_y d_c t_p \left[ 1 + \frac{3 b_{cf} t_{cf}^2}{d_b d_c t_p} \right], \text{ where for this case } \phi_v = 0.8
\tag{10.8.139}
$$
ii) Panel zone thickness : The panel zone thickness $t_z$ shall conform to the following :
$$
t_z \geq (d_z + w_z)/90
\tag{10.8.140}
$$
For this purpose $t_z$ shall not include any doubler plate thickness unless the doubler plate is connected to the web with plug welds adequate to prevent local buckling of the plate.
iii) Panel zone doubler plates : Doubler plates provided to increase the design strength of the panel zone or to reduce the web depth-thickness ratio shall be placed close to the column web and welded across the plate width top and bottom with a minimum fillet weld as specified in Table (6.10.9). The doubler plates shall be fastened to the column flanges using either butt or fillet welded joints to develop the design shear strength of the doubler plate.
d) Beam Limitations
i) Beam Flange Area : Abrupt changes in beam flange areas are not permitted within possible plastic hinge regions.
ii) Width-thickness Ratios : Beams shall comply with the limiting width thickness ratio stipulated in Table 6.10.5 in lieu of those in Table 6.10.4.
e) Continuity Plates : Continuity plates shall be provided if the nominal column local flange bending strength as given by Eq (10.8.127) is less than $1.8 \times 10^{-3} F_{yb} b_f t_{bf}$. Continuity plates shall be fastened by welds to both the flanges and webs or doubler plates of columns.
f) Column-Beam Moment Ratio : At any beam to column connection, one of the following relationships shall be satisfied :
**Table 6.10.5**
**Limiting Width-Thickness Ratios for Compression Elements**
| Description of Element | Width-Thickness Ratio | Limiting Width-Thickness Ratios |
| ----------------------------------------------------------------------------------------------------------- | --------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Flanges of I-shaped nonhybrid sections and channels in flexure; Flanges of I-shaped hybrid beams in flexure | $b/t$ | $136/\sqrt{F_y}$ |
| Webs in combined flexural and axial compression | $h_c/t_w$ | For $P_u/\phi_b P_y \leq 0.125$: $\dfrac{1365}{\sqrt{F_y}} \left[ 1 - \dfrac{1.54 P_u}{\phi_b P_y} \right]$ For $P_u/\phi_b P_y > 0.125$: $\dfrac{500}{\sqrt{F_y}} \left[ 2.33 - \dfrac{P_u}{\phi_b P_y} \right] \geq \dfrac{665}{\sqrt{F_y}}$ |
$$
\frac{\sum Z_c (F_{yc} - P_{uc}/A_g)}{\sum Z_b F_{yb}} \geq 1.0, \text{ where } P_{uc} \text{ (in compression)} \geq 0
\tag{10.8.141}
$$
$$
\frac{\sum Z_c (F_{yc} - P_{uc}/A_g)}{1000 V_n d_b \left( H/[H - d_b] \right)} \geq 1.0, \text{ where } P_{uc} \text{ (in compression)} \geq 0
\tag{10.8.142}
$$
In Eq (10.8.142), $V_n$ is the nominal strength of the panel zone as determined from Eq (10.8.139), $d_b$ is the average overall depth of the beams framing into the connection, and *H* is the average of the storey heights above and below the connection.
These requirements need not apply in the following cases, provided that the columns conform to the requirements of (d) above:
i) For columns with $P_{uc} < 0.3 \times 10^{-3} F_y A_g$.
ii) For columns in any storey that has a total design lateral shear strength 50 per cent greater than that of the storey above.
iii) For any column not included in the design to resist the required seismic shears, although the column is included in the design to resist axial overturning forces.
g) Beam to Column Connection Restraint
i) Restrained Connections :
A. Column flanges at a beam to column connection require lateral support only at the level of the top flanges of the beams when a column can be shown to remain outside of the panel zone. This can be satisfied by one of the following conditions :
1. The ratios given by Eq (10.8.141) or (10.8.142) are greater than 1.25.
2. The column remains elastic for load combination 7 specified in Sec 2.7.5.2 of Chapter 2, Loads.
B. When a column cannot be shown to remain elastic outside of the panel zone, the following provisions apply :
1. The column flanges shall be laterally supported at the levels of both top and bottom beam flanges.
2. Each column flange lateral support shall be designed for a required strength equal to 1.5 per cent of the nominal beam flange strength $(F_y b_f t_f)$.
3. Column flanges shall be laterally supported either directly or indirectly by means of the column web or beam flanges.
ii) Unrestrained Connections : A column containing a beam to column connection with no lateral support transverse to the seismic frame at the connection shall be designed using the distance between adjacent lateral supports as the column height and conform to Sec 10.8.8.1, except that :
A. The required column strength shall be determined from the load combination 5 specified in Sec 2.7.5.2 of Chapter 2, where E is the least of :
1. The amplified earthquake force E′.
2. 125 per cent of the frame design strength based on either beam or panel zone design strengths.
B. The nominal column axial strength $P_n$ shall be based on a pin ended column.
C. The *L/r* for these columns shall not exceed 60.
D. The required column moment $M_{uy}$ shall include that caused by the beam flange force specified in i(B-2) above plus the added P-Delta moment due to the resulting column flange displacement.
h) Lateral Support of Beams : Both flanges of beams shall be laterally supported directly or indirectly. The unbraced length between lateral supports shall not exceed $17237 r_y/F_y$. In addition, lateral supports shall be placed at concentrated loads where a hinge may form.
#### 10.8.12.9 Requirements for Concentrically Braced Frames (CBF)
a) Scope : The provisions of this section apply to all braced frames except Eccentric Braced Frames (EBF) designed in accordance with Sec 10.8.12.10. Those members which resist seismic forces totally or partially by shear and flexure shall be designed in accordance with Sec 10.8.12.8.
b) Bracing Members
i) Slenderness : Bracing members shall have an $L/r \leq 1890/\sqrt{F_y}$ in Seismic Zone 3 except as permitted in (e) below.
ii) Compressive Design Strength : The design strength of a bracing member in axial compression shall be determined by $0.8 \phi_c P_n$.
iii) Lateral Force Distribution : In Seismic Zone 3, the summation of the horizontal components of lateral seismic force in tension or alternatively in compression along any line of bracing shall not exceed 70% of the total force on that line, unless the nominal strength $P_n$ of the member in compression is larger than the required strength $P_u$ resulting from the application of the load combinations 7 and 8 specified in Sec 2.7.5.2 of Chapter 2, Loads. A line of bracing, for the purpose of this provision, is defined as a single line or parallel lines whose offset is within 10 per cent of the building dimension perpendicular to the line of bracing.
iv) Width-thickness Ratios : Width-thickness ratios of stiffened and unstiffened compression elements in braces shall comply with Sec 10.8.3. Braces shall be compact or noncompact, but not slender members. Circular hollow sections shall have an outside diameter to wall thickness ratio not exceeding $8965/F_y$. Rectangular tubes shall have the flat width to wall thickness not exceeding $290/\sqrt{F_y}$, unless the tube walls are stiffened.
v) Built-up Member Stitches : For all built-up braces, the first bolted or welded stitch on each side of the mid-length of a built-up member shall be designed to transmit a force equal to 50% of the nominal strength of one element to the adjacent element. Not less than two stitches shall be equally spaced about the member centre line.
c) Bracing Connections
i) Forces : The required strength of bracing joints (including beam to column joints if part of the bracing system) shall be the least of the following :
A. The design axial tension strength of the bracing member.
B. The force in the brace resulting from the load combinations 7 and 8 specified in Sec 2.7.5.2 of Chapter 2, Loads.
C. The maximum force that can be transferred to the brace by the system.
ii) Net Area : In bolted brace joints, the minimum ratio of effective net section area to gross section area shall be limited by :
$$
A_e / A_g = \frac{1.2 \alpha P_u^*}{\phi_t P_n}
$$
where
$\alpha$ = Fraction of the member force from (i) above, that is transferred across a particular net section.
$P_u^*$ = Required axial strength of the brace as determined in (i) above.
$\phi_t$ = Resistance factor for tension = 0.75.
iii) Gusset Plates
A. For braces that can buckle in the plane of the gusset plate, the gusset and other parts of the connection shall have a design strength equal to or greater than the nominal in-plane bending strength of the brace.
B. For braces which can buckle out-of-plane of the gusset plate, the brace shall terminate on the gusset a minimum of two times the gusset thickness from a line about which the gusset plate can bend unrestrained by the column or beam joints. The gusset plate shall be designed to carry the compressive design strength of the brace member without local buckling of the gusset plate. For braces designed for axial load only, the bolts or welds shall be designed to transmit the brace forces along the centroids of the brace elements.
d) Special Bracing Configuration Requirements
i) V Bracing
A. The design strength of V brace members shall be at least 1.5 times the required strength using load combinations 5 and 6 specified in Sec 2.7.5.2 of Chapter 2, Loads.
B. A beam intersected by V braces shall be continuous between columns.
C. A beam intersected by V braces shall be capable of supporting all tributary dead and live loads assuming the bracing is not present.
D. The top and bottom flanges of the beam at the point of intersection of V braces shall be designed to support a lateral force equal to 1.5 per cent of the nominal beam flange strength $(F_y b_f t_f)$.
ii) K Bracing
A. In Seismic Zone 3, K bracing shall be prohibited except for those framing systems meeting the requirements of (e) below.
B. In Seismic Zone 2, with importance factor I greater than 1.0, K bracing shall meet the requirements for V bracing.
e) Low Buildings : Braced frames not meeting the requirements of (b) through (d) above may be used in buildings not over two storeys and in roof structures if load combinations 7 and 8 specified in Sec 2.7.5.2 of Chapter 2, Loads, are used for determining the required strength of the members and connections.
#### 10.8.12.10 Requirements for Eccentrically Braced Frames (EBF)
a) Scope : Eccentrically braced frames shall be designed so that under earthquake loading, yielding will occur primarily in the links. The diagonal braces, the columns, and the beam segments outside of the links shall be designed to remain essentially elastic under the maximum forces that can be generated by the fully yielded and strain hardened links. In EBF, plastic hinges shall not develop in columns at floor beam levels up to an amplified frame displacement of E′/E times that produced by E.
b) Links
i) Links shall comply with the width-thickness ratios in Table 6.10.5.
ii) The specified minimum yield stress of steel used for links shall not exceed $F_y = 345 \text{ N/mm}^2$.
iii) The web of a link shall be single thickness without doubler plate reinforcement and without openings.
iv) The required shear strength of the link $V_u$ shall not exceed the design shear strength of the link $\phi_v V_n$ defined as the lesser of $\phi_v V_y$ or $2000 \phi_b M_p / e$, where $V_y = 0.6 \times 10^{-3} F_y d t_w$, $\phi_b = \phi_v = 0.9$ and $e$ = link length, except as limited by (vi) below.
v) If the required axial strength $P_u$ in a link is less than or equal to $0.15 P_y$, where $P_y = 10^{-3} A_g F_y$, the effect of axial force on the link design shear strength need not be considered.
vi) If the required axial strength $P_u$ in a link exceeds $0.15 P_y$, the following additional limitations shall apply :
A. The link design shear strength shall be the lesser of $\phi_v V_{ya}$ or $2000 \phi_b M_{pa}/e$,
where
$$
V_{ya} = V_y \sqrt{1 - (P_u/P_y)^2}
$$
$$
M_{pa} = 1.18 M_p \left[ 1 - (P_u/P_y) \right]
$$
and $\phi_b = \phi_v = 0.9$
B. The length of the link in mm, shall not exceed :
$$
\left[ 1.15 - 0.5 (P_u/V_y)(A_w/A_g) \right] 1600 M_p/V_y \text{ for } (P_u/V_y)(A_w/A_g) \geq 0.3 \text{ and }
$$
$$
1600 M_p/V_y \text{ for } (P_u/V_y)(A_w/A_g) < 0.3
$$
where $A_w = d t_w$.
vii) The link rotation angle is the plastic angle between the link and the beam outside of the link when the total storey drift is E′/E times the drift determined using the specified base shear V. Except as noted in d(iii) below, the link rotation angle shall not exceed the following values :
A. 0.09 radian for links of length $1600 M_p/V_y$ or less, provided the fundamental period of the EBF is equal to or greater than 1.0 second; otherwise the link rotation angle shall not exceed 0.08 radian.
B. 0.02 radian for links of length $2600 M_p/V_y$ or greater.
C. Linear interpolation shall be used for links of length between $1600 M_p/V_y$ and $2600 M_p/V_y$.
c) Link Stiffeners
i) Full depth web stiffeners shall be provided on both sides of the link web at the diagonal brace ends of the link. These stiffeners shall have a combined width not less than $(b_f - 2t_w)$ and a thickness not less than $0.75 t_w$ nor 10 mm, whichever is larger, where $b_f$ and $t_w$ are the link flange width and link web thickness, respectively.
ii) Links shall be provided with intermediate web stiffeners as follows :
A. Links of lengths $1600 M_p/V_y$ or less shall be provided with intermediate web stiffeners spaced at intervals not exceeding $(30 t_w - d/5)$ for a link rotation angle of 0.09 radian or $(52 t_w - d/5)$ for link rotation angles of 0.03 radian or less. Linear interpolation shall be used for values between 0.03 and 0.09 radians.
B. Links of length greater than $2600 M_p/V_y$ and less than $5000 M_p/V_y$ shall be provided with intermediate web stiffeners placed at a distance of $1.5 b_f$ from each end of the link.
C. Links of length between $1600 M_p/V_y$ and $2600 M_p/V_y$ shall be provided with intermediate web stiffeners meeting the requirements of (A) and (B) above.
D. No intermediate web stiffeners are required in links of lengths greater than $5000 M_p/V_y$.
E. Intermediate link web stiffeners shall be full depth. For links less than 625 mm in depth, stiffeners are required on only one side of the link web. The thickness of one sided stiffeners shall not be less than $t_w$ nor 10 mm, and the width shall be not less than $\left[ (b_f/2) - t_w \right]$. For links 625 mm in depth or greater, similar intermediate stiffeners are required on both sides of the web.
iii) Fillet welds connecting link stiffener to the link web shall have a design strength adequate to resist a force of $A_{st} F_y$, where $A_{st}$ equals the area of the stiffener. The design strength of fillet welds fastening the stiffener to the flanges shall be adequate to resist a force of $A_{st} F_y / 4$.
d) Link to Column Connections : Where a link is connected to a column, the following additional requirements shall apply :
i) Links connected to columns shall not exceed the length of $1600 M_p/V_y$ unless it can be demonstrated that the link to column connection is adequate to develop the required inelastic rotation of the link.
ii) The link flanges shall have complete penetration welded joints to the column. The connection of the link web to the column shall be welded to develop the design axial, shear and flexural strength of the link web.
iii) Where the link is connected to the column web, the link flanges shall have complete penetration welded joints to connection plates and the web connection shall be welded to develop the design axial, shear and flexural strength of the link web. The link rotation angle shall not exceed 0.015 radian for any link length.
e) Lateral Support of Link : Lateral supports shall be provided at both the top and bottom flanges of link at the ends of the link. End lateral supports of links shall have a design strength of 4% of the link flange nominal strength computed as $F_y b_f t_f$.
f) Diagonal Brace and Beam Outside of Link
i) The required axial and moment strengths of each diagonal brace and the beam outside of the link shall be the axial forces and moments generated by 1.5 times the design shear strength of the link as defined in (b) above. The nominal strengths of the diagonal brace and of the beam outside of the link, as determined by Sec 10.8.8.1 shall exceed the required strengths as defined above.
ii) Diagonal brace to link connections shall develop the nominal strength of the brace and transfer this force to the beam. No part of the brace to beam connection shall extend over the link length. If the brace resists a portion of the link end moment as described above, the brace to beam connection shall be designed as fully restrained (Type FR).
iii) The beam outside of the link shall be provided with sufficient lateral support to maintain the stability of the beam under the forces generated by at least 1.5 times the design shear strength of the link. Lateral supports shall be provided at both top and bottom flanges of the beam and shall have a strength to resist at least 1.5 per cent of the beam flange nominal strength computed as $F_y b_f t_f$.
iv) The width-thickness ratio of brace shall satisfy Sec 10.8.12.9b(iv).
g) Beam to Column Connections : Beam to column connections away from links are permitted to be designed as a pin in the plane of the web. The connection shall have a strength to resist rotation about the longitudinal axis of the beam based on two equal and opposite rotation forces of at least 1.5 per cent of the beam flange nominal strength computed as $F_y b_f t_f$ acting laterally on the beam flanges.
h) Required Column Strength : The required strength of columns shall be determined by load combinations 5 and 6 specified in Sec 2.7.5.2 of Chapter 2, Loads, except that the moments and axial loads introduced into the column at the connection of a link or brace shall not be less than those generated by 1.25 times the design strength of the link.
## 10.9 CONNECTIONS, JOINTS AND FASTENERS
This section provides the requirements for the design of connectors i.e. bolts, welds, rivets, etc. and connecting elements such as plates, stiffeners, gussets, angles, brackets, etc.
### 10.9.1 Design Provisions
#### 10.9.1.1 Design Basis
a) In Working Stress Design connections shall be designed such that the calculated stress in the connectors or connecting elements for service loads shall not exceed the allowable stress stipulated in Sec 10.7 and 10.9.
b) In Load Factor Design the connections shall be designed such that the required strength in the connectors and connecting elements for factored loads shall not exceed the design strength.
#### 10.9.1.2 Simple Connections
Simple Connections may be designed for the reaction shears only. It shall accommodate end rotations of unrestrained (simple) beams and to accomplish this, inelastic deformation in the connection is permitted.
#### 10.9.1.3 Moment Connections
End connections of restrained beams, girders and trusses shall be designed for the combined effect of forces resulting from moment and shear induced by the rigidity of the connections.
#### 10.9.1.4 Compression Members with Bearing Joints
When columns bear on bearing plates or are finished to bear at splices, there shall be sufficient connectors to hold all parts securely in place.
When other compression members are finished to bear, the splice material and its connectors shall be arranged to hold all parts in line and shall be designed for 50% of the strength of the member in Working Stress Design and for 50% of the factored strength of the member in Load Factor Design.
In Working Stress Design compression joints shall be proportioned to resist any tension developed by the specified lateral loads acting in conjunction with 75% of the calculated dead load stress and no live loads.
In Load Factor Design compression joints shall be proportioned to resist any tension developed by the factored load combination 6 specified in Sec 2.7.5.2 of Chapter 2, Loads.
#### 10.9.1.5 Minimum Connections
Except for lacing, sagbars and girts, all connections shall be proportioned to support a service load not less than 27 kN in Working Stress Design while in Load Factor Design the connection shall be proportioned to support a factored load not less than 45 kN.
#### 10.9.1.6 Splices in Heavy Sections
The following requirement applies to ASTM A6 Group 4 and 5 rolled shapes, or shapes built up by welding plates more than 50 mm thick together to form the cross-section, and where the cross-section is to be spliced and subjected to primary tensile stresses due to tension or flexure. When the individual elements of the cross section are spliced prior to being joined to form cross-section in accordance with Sec 3.4.6 of AWS D1.1, the applicable provisions of AWS D1.1 shall apply in lieu of the requirements of this section.
When tensile forces in these sections are to be transmitted through splices by full penetration groove welds, weld access hole details as given in Sec 10.9.1.7, welding preheat requirements as given in Sec 10.9.2.6 and thermal cut surface preparation and inspection requirements as given in Sec 10.11.2.2 shall be applicable.
At tension splices in these sections, weld tabs and backing shall be removed and the surfaces ground smooth.
When splicing these sections, and where the section is to be used as a primary compression member, all weld access holes required to facilitate groove welding operations shall satisfy the requirements of Sec 10.9.1.7.
Alternatively, splicing of such members subjected to compression, including members which are subjected to tension due to wind or seismic loads, may be accomplished using splice details which do not induce large weld shrinkage strains such as partial-penetration flange groove welds with fillet-welded surface lap plate splices on the web, or with bolted or combination of bolted and fillet welded lap plate splices.
#### 10.9.1.7 Beam Copes and Weld Access Holes
All weld access holes required to facilitate welding operations shall have a length from the toe of the weld preparation not less than $1\frac{1}{2}$ times the thickness of the material in which the hole is made. The height of the access hole shall be adequate for deposition of sound weld metal in the adjacent plates and provide clearance for weld tabs. In hot rolled shapes and built-up shapes, all beam copes and weld access holes shall be shaped free of notches or sharp reentrant corners except that, when fillet web to flange welds are used in built-up shapes, access holes are permitted to terminate perpendicular to the flange.
For Group 4 and 5 shapes and built-up shapes of material more than 50 mm thick, the thermally cut surfaces of beam copes and weld access holes shall be ground to bright metal and inspected by either magnetic particle or dye penetrant methods. If the curved transition portion of weld access holes and beam copes are formed by predrilled or sawed holes, that portion of the access hole or cope need not be ground. Weld access holes and beam copes in other shapes need not be ground nor inspected by dye penetrant or magnetic particle.
#### 10.9.1.8 Placement of Welds, Bolts and Rivets
Groups of welds, bolts or rivets at the ends of any member which transmit axial stress into that member shall be sized so that the centre of gravity of the group coincides with the centre of gravity of the member, unless provision is made for the eccentricity. The foregoing provision is not applicable to end connections of statically loaded single-angle, double-angle and similar members. Eccentricity between the gravity axes of such members and the gauge lines for their riveted or bolted end connections may be neglected in statically loaded members.
#### 10.9.1.9 Bolts in Combination with Welds
In new work, A307 bolts or high strength bolts used in bearing type connections shall not be considered as sharing the stress in combination with welds. Welds, if used, shall be provided to carry the entire stress in the connection. High strength bolts designed for slip-critical connections may be considered as sharing the stress with the welds.
In making welded alterations to structures, existing rivets and high strength bolts tightened to the requirements for slip-critical connections are permitted for carrying stresses resulting from loads present at the time of alteration, and the welding need only be adequate to carry the additional load.
#### 10.9.1.10 High strength Bolts in Slip-critical Connections in Combination with Rivets
In both new work and alterations, high strength bolts in slip-critical connections may be considered as sharing the load with rivets.
#### 10.9.1.11 Limitations of Bolted and Welded Connections
Fully tensioned high strength bolts (see Table 6.10.12) or welds shall be used for the following connections :
Column splices in all tier structures 60 m or more in height,
Column splices in tier structures 30 m to 60 m in height, if the least horizontal dimension is less than 40% of the height,
Column splices in tier structures less than 30 m in height, if the least horizontal dimension is less than 25% of the height,
Connections of all beams and girders to columns and of any other beams and girders on which the bracing of columns is dependent, in structures over 40 m in height,
In all structures carrying cranes of over 50 kN capacity : roof truss splices and connections of trusses to columns, column splices, column bracing, knee braces and crane supports,
Connections for supports of running machinery or of other live loads which produce impact or reversal of stress, and
Any other connections stipulated on the design plans.
In all other cases, connections may be made with high strength bolts tightened to the snug-tight condition or with A307 bolts.
For the purpose of this section, the height of a tier structure shall be taken as the vertical distance from the curb level to the highest point of the roof beams in the case of flat roofs, or to the mean height of the gable in the case of roofs having a rise of more than 1 in $4\frac{1}{2}$. Where the curb level has not been established, or where the structure does not adjoin a street, the mean level of the adjoining land shall be used instead of curb level. Penthouses may be excluded in computing the height of the structure.
### 10.9.2 Welds
All provisions of the AWS D1.1 : Structural Welding Code - Steel, except its Sec 2.3.2.4, 2.5, 8.13.1, 9 and 10 shall apply to work executed under this specification.
#### 10.9.2.1 Groove Welds
a) Effective Area : The effective area of groove welds shall be considered as the effective length of the weld times the effective throat thickness.
The effective length of a groove weld shall be the width of the part joined.
The effective throat thickness of a complete penetration groove weld shall be the thickness of the thinner part joined.
The effective throat thickness of a partial-penetration groove weld shall be as shown in Table 6.10.6.
**Table 6.10.6**
**Effective Throat Thickness of Partial Penetration Groove Welds**
| Welding Process | Welding Position | Included Angle at Root of Groove | Effective Throat Thickness |
| ---------------------------------------------------------------- | ---------------- | --------------------------------------- | --------------------------- |
| Shielded metal arc; Submerged arc; Gas metal arc; Flux-cored arc | All | J or U joint | Depth of chamfer |
| | All | Bevel or V joint $\geq 60°$ | Depth of chamfer |
| | All | Bevel or V joint $< 60°$ but $\geq 45°$ | Depth of chamfer minus 3 mm |
The effective throat thickness of a flare groove weld when flush to the surface of a bar or 90° bend in a formed section shall be as shown in Table 6.10.7. Random sections of production welds for each welding procedure, or such test sections as may be required by design documents, shall be used to verify that the effective throat is consistently obtained.
b) Limitations : The minimum effective throat thickness of a partial penetration groove weld shall be as shown in Table 6.10.8. Minimum effective throat thickness is determined by the thicker of the two parts joined, except that the weld size need not exceed the thickness of the thinnest part joined though a larger size is required by calculation. For this exception, particular care shall be taken to provide sufficient preheat for soundness of the weld.
**Table 6.10.7**
**Effective Throat Thickness of Flare Groove Welds**
| Type of Weld | Radius (R) of Bar or Bend | Effective Throat Thickness |
| ------------------ | ------------------------- | -------------------------- |
| Flare bevel groove | All | $\dfrac{5}{16} R$ |
| Flare V-groove | All | $\dfrac{1}{2} R^*$ |
\* Use $\dfrac{3}{8} R$ for Gas Metal Arc Welding (except short circuiting transfer process) when $R \geq 12$ mm
**Table 6.10.8**
**Minimum Effective Throat Thickness of Partial Penetration Groove Welds**
| Material Thickness of Thicker Part Joined, mm | Minimum Effective Throat Thickness, mm |
| --------------------------------------------- | -------------------------------------- |
| To 6 inclusive | 3 |
| Over 6 to 12 | 5 |
| Over 12 to 20 | 6 |
| Over 20 to 40 | 8 |
| Over 40 to 60 | 10 |
| Over 60 to 150 | 12 |
| Over 150 | 16 |
#### 10.9.2.2 Fillet Welds
a) Effective Area : The effective area of fillet welds shall be taken as the effective length times the effective throat thickness.
The effective length of fillet welds, except fillet welds in holes and slots, shall be the overall length of full size fillets, including returns.
The effective throat thickness of a fillet weld shall be the shortest distance from the root of the joint to the face of the diagrammatic weld, except that for fillet welds made by the submerged arc process, the effective throat thickness shall be taken equal to the leg size for 10 mm and smaller fillet welds, and equal to the theoretical throat plus 3 mm, for fillet welds larger than 10 mm.
For fillet welds in holes and slots, the effective length shall be the length of the centre line of the weld along the centre of the plane through the throat. In the case of overlapping fillets, the effective area shall not exceed the nominal cross-sectional area of the hole or slot in the plane of the faying surface.
b) Limitations : The minimum size of fillet welds shall be as shown in Table 6.10.9. Minimum weld size is dependent upon the thicker of the two parts joined, except that the weld size need not exceed the thickness of the thinner part. For this exception particular care shall be taken to provide sufficient preheat for soundness of the weld. Weld sizes larger than the thinner part joined are permitted if required by calculated strength. In the as-welded condition the distance between the edge of the base metal and the toe of the weld may be less than 1.5 mm provided the weld size is clearly verifiable.
**Table 6.10.9**
**Minimum Size of Fillet Welds**
| Material Thickness of Thicker Part Joined (mm) | Minimum Size of Fillet Weld \* (mm) |
| ---------------------------------------------- | ----------------------------------- |
| To 6 inclusive | 3 |
| Over 6 to 12 | 5 |
| Over 12 to 20 | 6 |
| Over 20 | 8 |
\* Leg dimension of fillet welds. Single-pass welds must be used.
The maximum size of fillet welds that is permitted along edges of connected parts shall be:
Not greater than the thickness of the material for less than 6 mm thick material.
Not greater than the thickness of the material minus 1.5 mm for material 6 mm or more in thickness, unless the weld is especially designated on the drawings to be built out to obtain full-throat thickness.
The minimum effective length of fillet welds designed on the basis of strength shall be not less than 4 times the nominal size, or else the size of the weld shall be considered not to exceed $\dfrac{1}{4}$ of its effective length. If longitudinal fillet welds are used alone in end connections of flat bar tension members, the length of each fillet weld shall be not less than the perpendicular distance between them. The transverse spacing of longitudinal fillet welds used in end connections of tension members shall not exceed 200 mm, unless the member is designed on the basis of effective net area in accordance with Sec 10.6.3.
Intermittent fillet welds are permitted to transfer calculated stress across a joint or faying surfaces when the strength required is less than that developed by a continuous fillet weld of the smallest size, and to join components of built-up members. The effective length of any segment of intermittent fillet welding shall be not less than 4 times the weld size, with a minimum of 40 mm.
In lap joints, the minimum lap shall be 5 times the thickness of the thinner part joined, but not less than 25 mm. Lap joints joining plates or bars subject to axial stress shall be fillet welded along the end of both lapped parts, except where the deflection of the lapped parts is sufficiently restrained to prevent opening of the joint under maximum loading.
Fillet welds in holes or slots may be permitted to transmit shear in lap joints or to prevent the buckling or separation of lapped parts and to join components of built-up members. Such fillet welds may overlap, subject to the provisions of this section. Fillet welds in holes or slots are not to be considered plug or slot welds.
Side or end fillet welds terminating at ends or sides, respectively, of parts or members shall, wherever practicable, be returned continuously around the corners for a distance not less than 2 times the nominal size of the weld. This provision shall apply to side and top fillet welds connecting brackets, beam seats and similar connections, on the plane about which bending moments are computed. For framing angles and simple end-plate connections which depend upon flexibility of the outstanding legs for connection flexibility, end returns shall not exceed 4 times the nominal size of the weld. Fillet welds which occur on opposite sides of a common plane shall be interrupted at the corner common to both welds. End returns shall be indicated on the design and detail drawings.
#### 10.9.2.3 Plug and Slot Welds
a) Effective Area : The effective shearing area of plug and slot welds shall be considered as the nominal cross-sectional area of the hole or slot in the plane of the faying surface.
b) Limitations : Plug or slot welds are permitted to transmit shear in lap joints or to prevent buckling of lapped parts and to join component parts of built-up members. The diameter of the hole for a plug weld shall not be less than the thickness of the part containing it plus 8 mm, rounded to the next higher value nor greater than the minimum diameter plus 3 mm or $2\dfrac{1}{2}$ times the thickness of the weld.
The minimum centre to centre spacing of plug welds shall be 4 times the diameter of the hole.
The minimum spacing of lines of slot welds in a direction transverse to their length shall be 4 times the width of the slot. The minimum centre to centre spacing in a longitudinal direction on any line shall be 2 times the length of the slot.
The length of slot for a slot weld shall not exceed 10 times the thickness of the weld. The width of the slot shall be not less than the thickness of the part containing it plus 8 mm, rounded to the next higher value, nor shall it be larger than $2\dfrac{1}{4}$ times the thickness of the weld. The ends of the slot shall be semicircular or shall have the corners rounded to a radius not less than the thickness of the part containing it, except those ends which extend to the edge of the part.
The thickness of plug or slot welds in material 16 mm or less in thickness shall be equal to the thickness of the material. In material over 16 mm thick, the thickness of the weld shall be at least $\dfrac{1}{2}$ the thickness of the material but not less than 16 mm.
#### 10.9.2.4 Allowable Stresses or Design Strength
For Working Stress Design the welds shall be proportioned to meet the stress requirements given in Table 6.10.10.
For Load Factor Design the design strength of welds shall be the lower value of $\phi F_{BM}$ and $\phi F_w$, when applicable. The values of $\phi$, $F_{BM}$, $F_w$ and the limitations thereon are given in Table 6.10.11.
**Table 6.10.10**
**Allowable Stress on Welds(1)**
| Type of Weld and Stress | Allowable Stress | Required Weld Strength Level(2, 3) |
| ----------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------ |
| **Complete-penetration Groove Welds** | | |
| Tension normal to effective area | Same as base metal | "Matching" weld metal shall be used |
| Compression normal to effective area | Same as base metal | Weld metal with a strength level equal to or less than "matching" weld metal is permitted |
| Tension or compression parallel to axis of weld | Same as base metal | (same as above) |
| Shear on effective area | 0.30 x nominal tensile strength of weld metal, N/mm² | (same as above) |
| **Partial-penetration Groove Welds(4)** | | |
| Compression normal to effective area | Same as base metal | Weld metal with a strength level equal to or less than "matching" weld metal is permitted |
| Tension or compression parallel to axis of weld(5) | Same as base metal | (same as above) |
| Shear parallel to axis of weld | 0.30 x nominal tensile strength of weld metal, N/mm² | (same as above) |
| Tension normal to effective area | 0.30 x nominal tensile strength of weld metal (N/mm²), except tensile stress on base metal shall not exceed 0.60 x yield stress of base metal | (same as above) |
| **Fillet Welds** | | |
| Shear on effective area | 0.30 x nominal tensile strength of weld metal, N/mm² | Weld metal with a strength level equal to or less than "matching" weld metal is permitted. |
| Tension or compression parallel to axis of weld(5) | Same as base metal | (same as above) |
| **Plug and Slot Welds** | | |
| Shear parallel to faying surfaces (on effective area) | 0.30 x nominal tensile strength of weld metal, N/mm² | Weld metal with a strength level equal to or less than "matching" weld metals is permitted |
Notes:
(1) The design of connected material is governed by Sec 10.7.4 through 10.7.7.
(2) For "Matching" weld metal, see Table 4.1.1 of AWS D1.1.
(3) Weld metal one strength level stronger than "matching" weld metal may be permitted.
(4) See Sec 10.9.2.1(b) for a limitation on use of partial penetration groove welded joints.
(5) Fillet welds and partial penetration groove welds joining the component elements of built-up members, such as flange to web connections, may be designed without regard to the tensile or compressive stress in these elements parallel to the axis of the welds.
#### 10.9.2.5 Combination of Welds
If two or more of the general types of weld (groove, fillet, plug, slot) are combined in a single joint, the effective capacity of each shall be separately computed with reference to the axis of the group in order to determine the allowable capacity of the combination.
#### 10.9.2.6 Preheat for Heavy Shapes
For ASTM A6 Group 4 and 5 shapes and welded built-up members made of plates more than 50 mm thick, a preheat equal to or greater than 175°C shall be used when making groove weld splices.
#### 10.9.2.7 Matching Steel
The choice of electrode for use with complete-penetration grove welds subjected to tension normal to the effective area shall be according to the requirements for matching steel stipulated in AWS D1.1 : Structural Welding Code-Steel.
### 10.9.3 Bolts, Rivets and Threaded Parts
#### 10.9.3.1 High strength Bolts
Except as otherwise provided in this Code, use of high strength bolts shall conform to the provisions of the RCSC Specification for Structural Joints Using ASTM A325 or A490 Bolts of AISC.
**Table 6.10.11**
**Design Strength of Welds**
| Types of Weld and Stress(1) | Material | Resistance Factor $\phi$ | Normal Strength $F_{BM}$ or $F_w$ | Required Weld Strength Level(2, 3) |
| ----------------------------------------------------- | --------------------------- | ------------------------ | --------------------------------- | ----------------------------------------------------------------------------------------- |
| **Complete Penetration Groove Weld** | | | | |
| Tension normal to effective area | Base | 0.90 | $F_y$ | "Matching" weld must be used |
| Compression normal to effective area | Base | 0.90 | $F_y$ | Weld metal with a strength level equal to or less than "matching" may be used. |
| Tension or compression parallel to axis of weld | | | | |
| Shear on effective area | Base
weld electrode | 0.90
0.80 | $0.60F_y$
$0.60F_{EXX}$ | |
| **Partial Penetration Groove Welds** | | | | |
| Compression normal to effective area | Base | 0.90 | $F_y$ | Weld metal with a strength level equal to or less than "matching" may be used. |
| Tension or compression parallel to axis of weld(4) | | | | |
| Shear parallel to axis of weld | Base(5)
weld electrode | 0.75 | $0.60F_{EXX}$ | |
| Tension normal to effective area | Base
weld electrode | 0.90
0.80 | $F_y$
$0.60F_{EXX}$ | |
| **Fillet Welds** | | | | |
| Shear on effective area | Base(5)
weld electrode | 0.75 | $0.60F_{EXX}$ | Weld metal with a strength level equal to or less than "matching" weld metal may be used. |
| Tension or compression parallel to axis of weld(4) | Base | 0.90 | $F_y$ | |
| **Plug or Slot Welds** | | | | |
| Shear parallel to faying surfaces (on effective area) | Base(5)
weld electrode | 0.75 | $0.60F_{EXX}$ | Weld metal with a strength level equal to or less than "matching" weld metal may be used. |
Notes:
(1) For definition of effective area, see Sec 10.9.2.
(2) For "matching" weld metal, see Table 4.1.1 of AWS D1.1.
(3) Weld metal one strength level stronger than "matching" weld metal may be permitted.
(4) Fillet welds and partial penetration groove welds joining component elements of built-up members, such as flange-to-web connections, may be designed without regard to the tensile or compressive stress in these elements parallel to the axis of the welds.
(5) The design of connected material is governed by Sec 10.9.4.2.
If required to be tightened to more than 50% of their minimum specified tensile strength, ASTM A449 bolts in tension and bearing type shear connections shall have an ASTM F436 hardened washer installed under the bolt head, and the nuts shall meet the requirements of ASTM A563. When assembled, all joint surfaces, including those adjacent to the washers, shall be free of scale, except tight mill scale. Except as noted below, all A325 and A490 bolts shall be tightened to a bolt tension not less than that given in Table 6.10.12. Tightening shall be done by the turn-of-nut method, a direct tension indicator or by calibrated wrench.
Bolts in connections not subjected to tension loads, where slip can be permitted and where loosening or fatigue due to vibration or load fluctuation are not design considerations, need only to be tightened to the snug-tight condition. The snug-tight condition is defined as the tightness attained by a few impacts of an impact wrench or the full effort of a worker with an ordinary spud wrench and must bring the connected plies into firm contact.
For Load Factor Design, the nominal strength value given in Table 6.10.13 for bearing type connections shall be used for bolts tightened to the snug-tight condition. Bolts to be tightened only to the snug-tight conditions shall be clearly indicated on the design and drawings.
#### 10.9.3.2 Size and Use of Holes
a) The maximum sizes of holes for bolts are given in Table 6.10.14 except that larger holes, required for tolerance on location of anchor bolts in concrete foundations, are permitted in column base details.
**Table 6.10.12**
**Minimum Bolt Tension, kN(1, 2)**
| Diameter, mm | Nominal Size, in ASTM A325 or A490 | A325 Bolts | A490 Bolts |
| ------------ | ---------------------------------- | ---------- | ---------- |
| 12 | $\dfrac{1}{2}$ | 53 | 67 |
| 16 | $\dfrac{5}{8}$ | 85 | 107 |
| 20 | $\dfrac{3}{4}$ | 125 | 156 |
| 22 | $\dfrac{7}{8}$ | 173 | 218 |
| 25 | 1 | 227 | 285 |
| 28 | $1\dfrac{1}{8}$ | 249 | 356 |
| 32 | $1\dfrac{1}{4}$ | 316 | 454 |
| 35 | $1\dfrac{3}{8}$ | 378 | 538 |
| 38 | $1\dfrac{1}{8}$ | 458 | 658 |
Notes:
(1) Equal to 0.70 of minimum tensile strength of bolts, rounded off to nearest kN, as specified in ASTM specifications for A325 and A490 bolts with UNC threads.
(2) The pretension values are based on nominal sizes in inch of ASTM bolts with UNC thread.
**Table 6.10.13**
**Design Strength of Fasteners**
| Description of Fasteners | Tensile Strength: Resistance Factor $\phi$ | Tensile Strength: Nominal Strength, N/mm² | Shear Strength in Bearing type Connections: Resistance Factor $\phi$ | Shear Strength in Bearing type Connections: Nominal Strength, N/mm² |
| ------------------------------------------------------------------------------------------------------- | ------------------------------------------ | ----------------------------------------- | -------------------------------------------------------------------- | ------------------------------------------------------------------- |
| A307 bolts | 0.75 | 310 (1) | 0.60 | 186 (2, 4) |
| A325 bolts, when threads are not excluded from shear planes | 0.75 | 620 | 0.60 | 372 (4) |
| A325 bolts, when threads are excluded from shear planes | 0.75 | 620 | 0.60 | 495 (4) |
| A490 bolts, when threads are not excluded from shear planes | 0.75 | 775 | 0.60 | 465 (4) |
| A490 bolts, when threads are excluded from the shear planes | 0.75 | 775 | 0.60 | 620 (4) |
| Threaded part meeting the requirements of Sec 10.3, when threads are not excluded from the shear planes | 0.75 | $0.75F_u$ (1, 3) | 0.65 | $0.45F_u$ |
| Threaded parts meeting the requirements of Sec 10.3, when threads are excluded from the shear planes | 0.75 | $0.75F_u$ (1, 3) | 0.65 | $0.60F_u$ |
| A502 Gr. 1. hot-driven rivets | 0.75 | 310 (1) | 0.65 | 250 (4) |
| A502 Gr. 2 & 3 hot-driven rivets | 0.75 | 410 (1) | 0.65 | 330 (4) |
Notes:
(1) Static loading only.
(2) Threads permitted in shear planes.
(3) The nominal tensile strength of the threaded portion of an upset rod, based upon the cross-sectional area at its major thread diameter, $A_b$ shall be larger than the nominal body area of the rod before upsetting times $F_y$.
(4) When bearing type connections used to splice tension members have a fastener pattern whose length, measured parallel to the line of force, exceeds 1250 mm, tabulated values shall be reduced by 20%.
b) Standard holes shall be provided in member to member connections, unless oversized, short-slotted or long-slotted holes in bolted connections are approved by the engineer. Finger shims up to 6 mm may be introduced into slip-critical connections designed on the basis of standard holes without reducing the allowable shear of the fastener.
c) Oversized holes are permitted in any or all plies of slip-critical connections, but they shall not be used in bearing type connections. Hardened washers shall be installed over oversized holes in an outer ply.
d) Short-slotted holes are permitted in any or all plies of slip-critical or bearing type connections. The slots are permitted without regard to direction of loading in slip-critical connections, but the length shall be normal to the direction of the load in bearing-type connections. Washers shall be installed over short-slotted holes in an outer ply; when high strength bolts are used, such washers shall be hardened.
e) Long-slotted holes are permitted in only one of the connected parts of either a slip-critical or bearing-type connection at an individual faying surface. Long-slotted holes may be used without regard to direction of loading in slip-critical connections, but shall be normal to the direction of load in bearing type connections. Where long-slotted holes are used in an outer ply, plate washers or a continuous bar with standard holes, having a size sufficient to completely cover the slot after installation, shall be provided. In high strength bolted connections, such plate washers or continuous bars shall be not less than 8 mm thick and shall be of structural grade material, but need not be hardened. If hardened washers are required for use of high strength bolts, the hardened washers shall be placed over the outer surface of the plate washer or bar.
f) When A 490 bolts over 25 mm diameter are used in slotted or oversize holes in external plies, a single hardened washer conforming to ASTM F436, except with 8 mm minimum thickness, shall be used in lieu of the standard washer.
**Table 6.10.14**
**Nominal Hole Dimensions**
| Bolt Dia mm | Standard (Dia) mm | Oversize (Dia) mm | Short-slot (Width × length) | Long-slot (Width × length) |
| :---------- | :---------------- | :---------------- | :-------------------------- | :------------------------- |
| 12 | 14 | 16 | 14 × 18 | 14 × 32 |
| 16 | 18 | 21 | 18 × 22 | 18 × 40 |
| 20 | 21 | 24 | 21 × 25 | 21 × 48 |
| 22 | 24 | 27 | 24 × 28 | 24 × 56 |
| 25 | 27 | 32 | 27 × 33 | 27 × 64 |
| ≥28 | d + 1.5 | d + 8 | (d+1.5) × (d+10) | (d+1.5) × (2.5×d) |
#### 10.9.3.3 Effective Bearing Area
The effective bearing area of bolts, threaded parts and rivets shall be the diameter multiplied by the length in bearing, except that for countersunk bolts and rivets $\frac{1}{2}$ the depth of the countersink shall be deducted.
#### 10.9.3.4 Tension and Shear
In Working Stress Design the allowable tension and shear stresses on bolts, threaded parts and rivets shall be as given in Table 6.10.15 of the nominal body area of rivets (before driving) or the unthreaded nominal body area of bolts and threaded parts other than upset rods (see foot note h, Table 6.10.15). In Load Factor Design the design strength of bolts, threaded parts shall be taken as the product of the resistance factor $\phi$ and the nominal strength given in Table 6.10.13 of the unthreaded nominal body area of bolts and threaded parts other than upset (see footnote (3) of Table 6.10.13). High strength bolts supporting applied load by direct tension shall be so proportioned that their average tensile stress, computed on the basis of nominal bolt area and independent of any initial tightening force, will not exceed the appropriate stress given in Table 6.10.15 and the design strength given in Table 6.10.13 for Working Stress Design and Load Factor Design respectively. The applied load shall be the sum of any tension resulting from prying action produced by deformation of the connected parts and external service load in case of Working Stress Design or factored load in case of Load Factor Design.
#### 10.9.3.5 Combined Tension and Shear in Bearing Type Connections
a) In Working Stress Design, bolts and rivets subjected to combined shear and tension shall be so proportioned that the tension stress $F_t$, in N/mm² on the nominal body area $A_b$ produced by forces applied to the connected parts, shall not exceed the values computed from the expressions in Table 6.10.16 where $f_v$, the shear stress produced by the same forces, shall not exceed the value for shear given in Table 6.10.15. When allowable stresses are increased for wind or seismic loads in accordance with Sec 10.7.2.2, the constants in the expressions listed in Table 6.10.16 shall be increased by 33% but the coefficient applied to $f_v$ shall not be increased.
b) In Load Factor Design, bolts and rivets subjected to combined tension and shear shall be so proportioned that the tension stress $f_t$ produced by factored loads on the nominal body area $A_b$ does not exceed the values computed from the expressions in Table 6.10.17. The value of $f_v$, the shear produced by the same factored loads, shall not exceed the values of shear for Load Factor Design given in Sec 10.9.3.4.
#### 10.9.3.6 Combined Tension and Shear in Slip-critical Joints
a) In Working Stress Design for A325 and A490 bolts used in slip-critical connections, the maximum shear stress allowed by Table 6.10.15 shall be multiplied by the reduction factor $(1-f_t/A_y T_b)$ where $f_t$ is the average tensile stress due to a direct load applied to all of the bolts in a connection and $T_b$ is the pretension load of the bolt specified in Table 6.10.12. When allowable stresses are increased for wind or seismic load in accordance with the provision of Sec 10.7.2.2, the reduced allowable shear stress shall be increased by 33%.
**Table 6.10.15**
**Allowable Shear Stress on Fasteners, N/mm²**
| Description of Fasteners | Allowable Tension (Ft) | Allowable Shear (Fs) | | | Bearing type Connections | |
| ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------- | -------------------- | ------------------- | -------------------------------- | ---------------------------------------------------- | -------- |
| | | | Standard size Holes | Oversize and Short-slotted Holes | Long-slotted Holes (Transverse Load / Parallel Load) | |
| A502, Gr. 1, hot-driven Rivets | 159(5) | | | | | 120(6) |
| A502, Gr. 2 and 3, hot-driven rivets | 200(5) | | | | | 152(6) |
| A307 bolts | 138(5) | | | | | 69(6,7) |
| Threaded parts meeting the requirements of Sec 10.3.1 and 10.3.2, and A449 bolts meeting the requirements of Sec 10.3.2, and when threads are not excluded from shear planes | 0.33F\_b(5, 8) | | | | | 0.17F\_u |
| Threaded parts meeting the requirements of Sec 10.3.1 and 10.3.2, and A449 bolts meeting the requirements of Sec 10.3.2 when threads are excluded from shear planes | 0.33 F\_u(5) | | | | | 0.22F\_u |
| A325 bolts, when threads are not excluded from shear planes | 303 | 117 | 103 | 83 | 69 | 145(6) |
| A325 bolts, when threads are excluded from shear planes | 303 | 117 | 103 | 83 | 69 | 207(6) |
| A490 bolts, when threads are not excluded from shear planes | 372 | 145 | 124 | 103 | 90 | 193(6) |
| A490 bolts, when threads are excluded from shear planes | 372 | 145 | 124 | 103 | 90 | 276(6) |
Notes: (1) See Sec 10.7.2.2.
(2) Class A (slip coefficient 0.33). Clean mill scale and blast-cleaned surfaces with Class A coatings. When specified by the Engineer, the allowable shear stress, $F_v$, for slip-critical connections having special faying surface conditions may be increased to the applicable value given in the RCSC Specification.
(3) For limitations on use of oversized and slotted holes, see Sec 10.9.3.2.
(4) Direction of load application relative to long axis of slot.
(5) Static loading only.
(6) When bearing-type connections used to splice tension members have a fastener pattern whose length, measured parallel to the line of force, exceeds 1250 mm, tabulated values shall be reduced by 20%.
(7) Threads permitted in shear planes.
(8) The tensile capacity of the threaded portion of an upset rod, based upon the cross-sectional area at its major thread diameter $A_b$ shall be larger than the nominal body area of the rod before upsetting times $0.60F_u$.
b) In Load Factor Design the design shear resistance of slip-critical joints shall be determined by using the values from Table 6.10.18 multiplied by $\phi = 1.0$, except $\phi = 0.85$ for the long-slotted holes when the load is in the direction of the slot. The shear on the bolt due to service loads shall be less than the tabulated
**Table 6.10.16**
**Allowable Tension Stress (Ft) for Fasteners in Bearing-type Connections**
| Description of Fasteners | Threads Included in Shear Plane | Threads Excluded from Shear Plane |
| ----------------------------------------- | ------------------------------- | --------------------------------- |
| A307 bolts | 180 − 1.8f\_s ≤ 140 | |
| A325 bolts | $\sqrt{(303)^2 − 4.39f_s^2}$ | $\sqrt{(303)^2 − 2.15f_s^2}$ |
| A490 bolts | $\sqrt{(372)^2 − 3.75f_s^2}$ | $\sqrt{(372)^2 − 1.82f_s^2}$ |
| Threaded parts, A449 bolts over 40 mm dia | 0.43F\_u − 1.8f\_s ≤ 0.33F\_u | 0.43F\_u − 1.4f\_s ≤ 0.33F\_u |
| A502 Gr. 1 rivets | 207 − 1.3f\_s ≤ 160 | |
| A502 Gr. 2 rivets | 262 − 1.3f\_s ≤ 200 | |
**Table 6.10.17**
**Tension Design Stress Limit (φFt), N/mm², for Fasteners in Bearing Type Connections**
| Description of Fasteners | Threads Included in the Shear Plane | Threads Excluded from the Shear Plane |
| ---------------------------------------------- | ----------------------------------- | ------------------------------------- |
| A307 bolts | 270 − 1.8f\_s ≤ 207 | |
| A325 bolts | 585 − 1.8f\_s ≤ 470 | 585 − 1.4f\_s ≤ 470 |
| A490 bolts | 730 − 1.8f\_s ≤ 580 | 730 − 1.4f\_s ≤ 580 |
| Threaded parts, A449 bolts over 40 mm diameter | 0.73F\_u − 1.8f\_s ≤ 0.56F\_u | 0.73F\_u − 1.4f\_s ≤ 0.56F\_u |
| A502 Gr. 1 rivets | 304 − 1.3f\_s ≤ 234 | |
| A502 Gr. 2 rivets | 407 − 1.3f\_s ≤ 310 | |
When a bolt in a slip-critical connection is subjected to a service tensile force T, the nominal resistance in Table 6.10.18 shall be multiplied by the reduction factor $(1 − T/T_b)$ where $T_b$ is the minimum pretension load from Table 6.10.12.
**Table 6.10.18**
**Nominal Slip-critical Shear Strength, N/mm², of High Strength Bolts(1)**
| Type of Bolt | Standard Size Holes | Oversize and Short Slotted Holes | Long slotted Holes(2) |
| ------------ | ------------------- | -------------------------------- | --------------------- |
| A325 | 117 | 103 | 83 |
| A490 | 145 | 124 | 103 |
Notes: (1) Class A (slip coefficient 0.33). Clean mill scale and blast-cleaned surfaces with class A coatings.
(2) Tabulated values are for the case of load application transverse to the slot. When the load is parallel to the slot, multiply tabulated values by 0.85.
#### 10.9.3.7 Bearing at Bolt Holes
a) For shear connections in Working Stress Design the allowable bearing on the projected area of bolts and rivets at the bolt holes for two or more bolts in the line of force shall be as follows, provided the end distance in the line of force is more than $1\frac{1}{2}d$ and the centre to centre distance of bolts is more than $3d$.
i) In standard or short-slotted holes
$$
F_p = 1.2F_u
\tag{10.9.1}
$$
ii) In long-slotted holes perpendicular to the direction of load
$$
F_p = 1.0F_u
\tag{10.9.2}
$$
On the projected area of the bolt or rivet closest to the edge in standard or short-slotted holes with the edge distance less than $1\frac{1}{2}d$ and in all connections with a single bolt in the line of force:
$$
F_p = LtF_u/2d \leq 1.2F_u
\tag{10.9.3}
$$
If deformation around the hole is not a design consideration and adequate spacing and edge distance are provided as required by Sec 10.9.3.8 and 10.9.3.9, the following equation is permitted in lieu of Eq (10.9.3):
$$
F_p = 1.5F_u
\tag{10.9.4}
$$
and the limit in Eq 10.9.3 shall be increased to $1.5F_u$.
b) For shear connections in Load Factor Design the design bearing strength on two or more bolts in the line of force is $\phi R_n$ ($\phi = 0.75$) provided the end distance in the line of force is more than $1\frac{1}{2}d$ and the centre to centre distance of bolts is more than $3d$.
i) In standard or short-slotted holes
$$
R_n = 2.4 \times 10^{-3} d t F_u
\tag{10.9.5}
$$
ii) In long-slotted holes perpendicular to the direction of load
$$
R_n = 2.0 \times 10^{-3} d t F_u
\tag{10.9.6}
$$
For the bolts closest to the edge, in all connections not covered by Eq (10.9.5) and (10.9.6), the design bearing of a single bolt or two or more bolts in line of force, each with an end distance less than $1\frac{1}{2}d$, shall be determined by $\phi R_n$ where $\phi = 0.75$.
$$
R_n = \frac{Lt F_u}{1000}
\tag{10.9.7}
$$
If deformation around the bolt hole is not a design consideration and adequate spacing and edge distance as required by Sec 10.9.3.8 and 10.9.3.9 is provided, the following expression may be used in lieu of Eq 10.9.5 and 10.9.6, where $\phi = 0.75$.
$$
R_n = 3.0 \times 10^{-3} d t F_u
\tag{10.9.8}
$$
#### 10.9.3.8 Minimum Spacing
The distance between centres of standard, oversized or slotted fastener holes shall not be less than $2\frac{1}{2}$ times the nominal diameter of the fastener (a distance of $3d$ is preferred) nor less than that required by the following, if applicable.
a) In Working Stress Design the centre to centre distance of holes, s, along a line of transmitted forces shall not be less than $3d$ when $F_p$ is determined by Eq (10.9.1) and (10.9.2). Otherwise, the distance between centres of holes shall not be less than the following:
i) For standard holes:
$$
s \leq 2000P/F_y(1 + d/2)
\tag{10.9.9}
$$
ii) For oversized and slotted holes: the distance required for standard holes in (i) above, plus the applicable increment $C_1$ from Table 6.10.19, but the clear distance between holes shall not be less than one bolt diameter.
b) In Load Factor Design the centre to centre distance of holes, s, along a line of transmitted forces shall not be less than $3d$ when $R_n$ is determined by Eq (10.9.5) and (10.9.6). Otherwise, the distance between centres of holes shall not be less than the following :
$$
s \leq \frac{1000P}{\phi F_y t} + \frac{d}{2}
\tag{10.9.10}
$$
where $\phi = 0.75$
#### 10.9.3.9 Minimum Edge Distance
a) In Working Stress Design the distance from the centre of a standard hole to an edge of a connected part shall be not less than the applicable value from Table 6.10.20 or the value from Eq (10.9.11), as applicable. Along a line of transmitted force, the distance from the centre of a standard hole to the edge of the connected part $L_c$ shall be not less than
$$
L_c \leq 2000P/F_u t
\tag{10.9.11}
$$
**Table 6.10.19**
**Values of Spacing Increment C₁, mm**
| Nominal Dia of Fastener | Oversize Holes | Slotted Holes | | Parallel to Line of Force |
| ----------------------- | -------------- | ------------------------------ | ----------- | ------------------------- |
| | | Perpendicular to Line of Force | Short Slots | Long Slots(1) |
| ≤ 22 | 3 | 0 | 5 | 1½d − 1.5 |
| 25 | 5 | 0 | 6 | 36 |
| ≥ 28 | 6 | 0 | 16 | 1½d − 1.5 |
Note: (1) When length of slot is less than the maximum allowed in Table 6.10.14, C₁ may be reduced by the difference between the maximum and actual slot lengths.
b) In Load Factor Design the distance from the centre of a standard hole to the edge of the connected part shall be not less than the applicable value from Table 6.10.20 nor the value from Eq 10.9.12, as applicable. Along a line of transmitted force, the distance from the centre of a standard hole to the edge of the connected part $L_c$ shall be not less than $1\frac{1}{2}d$ when $R_n$ is determined by Eq (10.9.5) and (10.9.6). Otherwise, the edge distance shall be not less than
$$
L_c \leq \frac{1000P}{\phi F_u t}
\tag{10.9.12}
$$
where $\phi = 0.75$
**Table 6.10.20**
**Minimum Edge Distance, mm**
**(Centre of Standard Hole to Edge of Connected Part)**
| Nominal Bolt or Rivet Dia (mm) | At Sheared Edges | At Rolled Edges of Plates, Shapes or Bars, Gas-cut or Saw-cut Edges(2) |
| ------------------------------ | ---------------- | ---------------------------------------------------------------------- |
| 12 | 22 | 20 |
| 16 | 28 | 22 |
| 20 | 32 | 25 |
| 22 | 38(3) | 28 |
| 25 | 45(3) | 32 |
| 28 | 50 | 38 |
| 32 | 57 | 41 |
| Over 32 | 45 × dia | 32 × dia |
Notes: (1) For oversized or slotted holes, see Table 6.10.21
(2) All edge distances in this column may be reduced 3 mm when the hole is at a point where stress does not exceed 25% of the maximum design strength in the element.
(3) These may be 32 mm at the ends of beam connection angles.
For both the Working Stress and the Load Factor Design methods, the distance from the centre of an oversized or slotted hole to an edge of a connected part shall be not less than that required for a standard hole plus the applicable increment $C_2$ from Table 6.10.21.
**Table 6.10.21**
**Values of Edge Distance Increment C₂, mm**
| Nominal Dia of Fastener (mm) | Oversized Holes | Slotted Holes | | Parallel to Edge |
| ---------------------------- | --------------- | --------------------- | -------------- | ---------------- |
| | | Perpendicular to Edge | Short Slots | Long Slots(1) |
| ≤ 22 | 1.5 | 3 | | |
| 25 | 3 | 3 | $\frac{3}{4}d$ | 0 |
| ≤ 28 | 3 | 5 | | |
Note: (1) When length of slot is less than maximum allowable (See Table 6.10.14), C₂ may be reduced by one-half the difference between the maximum and actual slot lengths.
#### 10.9.3.10 Maximum Edge Distance and Spacing
The maximum distance from the centre of any rivet or bolt to the nearest edge of parts in contact shall be 12 times the thickness of the connected part under consideration, but shall not exceed 150 mm. Bolted joints in unpainted steel exposed to atmospheric corrosion require special limitations on pitch and edge distance.
For unpainted, built-up members made of weathering steel which will be exposed to atmospheric corrosion, the spacing of fasteners connecting a plate and a shape or two-plate components in contact shall not exceed 14 times the thickness of the thinnest part 175 mm, and the maximum edge distance shall not exceed eight times the thickness of the thinnest part 125 mm.
### 10.9.4 Shear Rupture
#### 10.9.4.1 Working Stress Design
At beam end connections where the top flange is coped, and in similar situations where failure might occur by shear along a plane through the fasteners, or by a combination of shear along a plane through the fasteners plus tension along a perpendicular plane :
$$
F_s = 0.30F_u
\tag{10.9.13}
$$
acting on the net shear area $A_c$ and,
$$
F_t = 0.50F_u
\tag{10.9.14}
$$
acting on the net tension area $A_t$.
The minimum net failure path on the periphery of welded connections shall be checked.
#### 10.9.4.2 Load Factor Design
The design strength for the limit state of rupture along a shear failure path in main members shall be taken as $\phi F_n A_{ns}$
where $\phi = 0.75$
$$
F_n = 0.6 F_u
\tag{10.9.15}
$$
### 10.9.5 Connecting Elements
This section covers the design of connecting elements, such as stiffeners, gussets, angles and brackets and the panel zones of beam to column connections.
#### 10.9.5.1 Eccentric Connections
Axially stressed intersecting members shall have their gravity axes intersect at one point, if practicable; if not, provision shall be made for bending and shearing stresses due to the eccentricity.
#### 10.9.5.2 Design
a) In Working Stress Design for situations where failure might occur by shear along a plane through the fasteners, or by a combination of shear along a plane through the fasteners plus tension along a perpendicular plane, see Sec 10.9.4.1.
b) In Load Factor Design the design strength $\phi R_n$ of welded, bolted and riveted connecting elements statically loaded in tension (i.e. splice and gusset plates) shall be the lower value obtained according to the limit state of yielding, fracture of the connecting element and block shear rupture.
i) For yielding of the connecting element
$$
\phi = 0.90
$$
$$
R_n = \frac{A_g F_y}{1000}
\tag{10.9.16}
$$
ii) For fracture of the connecting element where $A_n \leq 0.85A_g$
$$
\phi = 0.75
$$
$$
R_n = \frac{A_g F_u}{1000}
\tag{10.9.17}
$$
iii) For Block Shear Rupture : Block shear is a failure mode in which the resistance is determined by the sum of the shear strength on a failure path and the tensile strength on the perpendicular segment. When ultimate strength on the net section is used to determine the resistance on one segment, yielding on the gross section shall be used on the perpendicular segment; $\phi = 0.75$. Design strength shall be the larger of the two failure mode.
At beam end connections where the top flange is coped, and in similar situations, failure can occur by shear along a plane through the fasteners, acting in combination with tension along a perpendicular plane. In such case, the ultimate strength on the net section (shear or tension) shall be used to determine the resistance of one segment and yielding on the gross section (shear or tension) shall be used on the perpendicular segment, with $\phi = 0.75$ for both. By alternating the choice of which segment resistance is based on ultimate strength two possible values of design strength are obtained. The larger value shall be taken as the design strength.
For all other connecting elements, the design strength $\phi R_n$ shall be determined for the applicable limit state to insure that the design strength is equal to or greater than the required strength where $R_n$ is the nominal strength appropriate to the geometry and type of loading on the connecting element. The shear limit state is governed by :
$$
\phi = 0.80
$$
$$
R_n = 0.7 \times 10^{-3} A_g F_y
\tag{10.9.18}
$$
### 10.9.6 Fillers
In welded construction, any filler 6 mm or more in thickness shall extend beyond the edges of the splice plate and shall be welded to the part on which it is fitted with sufficient weld to transmit the splice plate stress and shall be long enough to avoid overstressing the filler. Any filler less than 6 mm thick shall have its edges flush with the edges of the splice plate and the weld size shall be the sum of the size necessary to carry the splice plus the thickness of the filler plate.
When bolts or rivets carrying loads pass through fillers thicker than 6 mm, except in slip-critical connections, the fillers shall be extended beyond the splice material and the filler extension shall be secured by enough bolts or rivets to distribute the total stress in the member uniformly over the combined section of the member and the filler, or an equivalent number of fasteners shall be included in the connection.
### 10.9.7 Splices
Groove welded splices in plate girders and beams shall develop the full strength of the smaller spliced section. Other types of splices in cross-sections of plate girders and beams shall develop the strength required by the stresses at the point of splice.
### 10.9.8 Bearings
#### 10.9.8.1
In Working Stress Design the allowable bearing stress $F_p$ on contact area of milled surfaces and ends of fitted bearing stiffeners; on projected area of pins in reamed, drilled or bored holes shall be
$$
F_p = 0.90F_y
\tag{10.9.19}
$$
On expansion rollers and rockers, N/mm²
$$
F_p = \left( \frac{F_y - 90}{20} \right) 0.66d
\tag{10.9.20}
$$
#### 10.9.8.2
In Load Factor Design the strength of surfaces in bearing is $\phi R_n$, where $\phi = 0.75$ and $R_n$ is defined below for various types of bearing.
a) Milled or Finished Surfaces : For milled surfaces, pins in reamed, drilled or bored holes, and ends of fitted bearing stiffeners,
$$
R_n = 2.0 \times 10^{-3} F_y A_{pb}
\tag{10.9.21}
$$
b) Expansion Roller and Rockers : For expansion rollers and rockers,
$$
R_n = 1.5(F_y - 90)d/20
\tag{10.9.22}
$$
### 10.9.9 Column Bases and Bearing on Supports
Proper provision shall be made to transfer the column loads and moments to the foundations :
#### 10.9.9.1
In Working Stress Design, the stresses due to service loads shall not exceed the following :
On brick in cement mortar $F_p = 1.72 \text{ N/mm}^2$
On the full area of a concrete support $F_p = 0.35f_c'$
On less than the full area of a concrete support $F_p = 0.35f_c' \sqrt{A_2/A_1} \leq 0.70f_c'$
#### 10.9.9.2
In Load Factor Design, the design bearing reactions due to factored loads on concrete shall not exceed $\phi c F_p'$.
On the full area of concrete support $F_p = 0.85f_c'A_1$
On less than the full area of concrete support $F_p = 0.85f_c'A_1 \sqrt{A_2/A_1}$
where $\phi_c = 0.60$, and
$$
\sqrt{A_2/A_1} \leq 2 ;
$$
### 10.9.10 Anchor Bolts
Anchor bolts shall be designed to provide resistance to all conditions of tension and shear at the bases of columns, including the net tensile components of any bending moment which may result from column, base restraint.
## 10.10 SERVICEABILITY REQUIREMENTS
This section provides the serviceability requirements under normal usage.
Allowable limits for selected parameters affecting serviceability are specified below.
### 10.10.1 Camber
If any special camber is necessary it shall be indicated in the design documents.
Trusses of 25 m or greater in span generally shall be cambered for approximately the dead load deflection. Crane girders of 23 m or greater in span generally shall be cambered for approximately the dead load deflection plus $\frac{1}{4}$ the live load deflection.
Beams and trusses detailed without specified camber shall be fabricated so that after erection any camber due to rolling or shop assembly shall be upward. If camber involves the erection of any member under a preload, this shall be noted in the design documents.
### 10.10.2 Expansion and Contraction
Provision shall be made for expansion and contraction appropriate to the service conditions of the structure.
### 10.10.3 Deflection and Vibration
#### 10.10.3.1 Deflection
Beams and girders supporting floors and roofs shall be proportioned with due regard to the deflection produced by the design loads. Beams and girders supporting plastered ceilings shall be so designed that the maximum live load deflection does not exceed $\frac{L}{360}$.
#### 10.10.3.2 Vibration
Beams and girders supporting large open floor areas free of partitions or other sources of damping shall be designed with due regard for vibration.
### 10.10.4 Corrosion
When appropriate, structural components shall be designed to tolerate corrosion or shall be protected against corrosion that impairs the strength or serviceability of the structure.
Exposed beams shall be sealed against corrosion of interior surfaces and spaced sufficiently apart to permit cleaning and painting.
## 10.11 FABRICATION, ERECTION AND QUALITY CONTROL
### 10.11.1 Shop Drawings
Shop drawings shall incorporate complete information necessary for the fabrication of the components of the structure, including the location, type and size of all welds, bolts and rivets. It shall be prepared in advance of the actual fabrication. These drawings shall be clearly distinguished between shop and field welds and bolts and shall clearly indicate type of high strength bolted connection such as snug tight or fully tensioned bearing, or slip-critical.
Shop drawings shall be made in conformity with the best practice and with due regard to speed and economy in fabrication and erection.
### 10.11.2 Fabrication
#### 10.11.2.1 Cambering, Curving and Strengthening
Local application of heat or mechanical means to introduce or correct camber, curvature and straightness are permitted. The temperature of heated areas, as measured by approved methods, shall not exceed 565°C for A852 steel, 590°C for A514 steel nor 650°C for other steels.
#### 10.11.2.2 Thermal Cutting
Thermally cut free edges subject to substantial tensile stress shall be free of gouges greater than 5 mm. Gouges greater than 5 mm deep and sharp notches shall be removed by grinding or repaired by welding. Thermally cut edges which are to have weld deposited upon them, shall be reasonably free of notches or gouges.
All reentrant corners shall be shaped to a smooth transition.
Beam copes and weld access holes shall meet the geometrical requirements of Sec 10.9.1.7. Beam copes and weld access holes in ASTM A6 Group 4 and 5 shapes and welded built-up shapes with material thickness greater than 50 mm, shall be preheated to a temperature of not less than 65°C prior to thermal cutting.
#### 10.11.2.3 Smoothing of Edges
Smoothing or finishing of sheared or thermally cut edges of plates or shapes will not be required unless specially called for in the design documents or included in a stipulated edge preparation for welding.
#### 10.11.2.4 Welded Construction
The technique of welding, the workmanship, appearance and quality of welds and the methods used in correcting nonconforming work shall be in accordance with AWS D1.1 : Structural Welding Code–Steel.
#### 10.11.2.5 High–strength Bolted Construction
All parts of bolted members shall be pinned or bolted and held together rigidly without assembling. Use of a drift pin in bolt holes during assembly shall not distort the metal or enlarge the holes. Poor matching of holes shall not be acceptable.
If the thickness of the material is not greater than the nominal diameter of the bolt plus 3 mm, the holes may be punched; otherwise the holes shall be either drilled or sub-punched and reamed. The die for all sub-punched holes, shall be at least 1.5 mm smaller than the nominal diameter of the bolt. Holes in A514 steel plates over 12 mm thick shall be drilled.
Surfaces of high strength bolted parts in contact with the bolt head and nut shall not have a slope of more than 1:20 respect to a perpendicular to bolt axis. Where the slope of the surface exceeds 1:20, a beveled washer shall be used to compensate for the lack of parallelism. High strength bolted parts shall fit solidly together when assembled and shall not be separated by gaskets or any other interposed compatible materials.
When assembled, all joint surfaces, including surface adjacent to the bolt head and nut, shall be free of scale, except tight mill scale, and shall be free of direct or other foreign material. Burrs that would prevent solid seating of the connection parts in the snug-tight condition shall be removed. Contact surfaces within slip-critical connections shall be free of oil, paint, or other coatings.
#### 10.11.2.6 Compression Joints
Compression joints which depend on contact bearing as part of the splice capacity shall have the bearing surfaces of individual fabricated pieces prepared by milling, sawing or other suitable means.
#### 10.11.2.7 Dimensional Tolerances
Dimensional tolerances shall be as specified in the Code of Standard Practice of the American Institute of Steel Construction.
#### 10.11.2.8 Finishing of Column Base
Columns base and base plates shall be finished in accordance with the following requirements :
a) Rolled steel bearing plates 50 mm or less in thickness are permitted without milling, provided a satisfactory contact bearing is obtained; rolled steel bearing plates over 50 mm but not over 100 mm in thickness may be straightened by pressing, or if presses are not available, by milling of all bearing surfaces except as noted in (iii) and (iv) below, to obtain a satisfactory contact bearing; rolled steel bearing plates over 100 mm thick shall be milled for all bearing surfaces (except as noted in (iii) and (iv) below).
b) Column bases other than rolled steel bearing plates shall be milled for all bearing surfaces (except as noted in (iii) and (iv) below).
c) The bottom surfaces of bearing plates and column bases which are grouted to insure full bearing contact on foundations need not be milled.
d) The top surfaces of base plates with columns full-penetration welded need not be pressed or milled.
### 10.11.3 Erection
#### 10.11.3.1 Alignment of Column Bases
Column bases shall be set level and to correct elevation with full bearing on concrete or masonry.
#### 10.11.3.2 Bracing
The frame of steel skeleton buildings shall be carried up true and plumb within the limits defined in the Code of Standard Practice of the American Institute of Steel Construction. Temporary bracing shall be provided in accordance with the requirements of the Code of Standard Practice wherever necessary to take care of all loads to which the structure may be subject, including equipment and the operation of the same. Such bearing shall be left in place as long as may be required for safety.
Wherever erection equipment or other loads are supported during erection, proper provision shall be made to take care of stresses resulting from such loads.
#### 10.11.3.3 Alignment
No permanent bolting or welding shall be performed until the elements have been properly aligned.
#### 10.11.3.4 Fit of Column Compression Joints
Lack of contact bearing not exceeding a gap of 1.5 mm, regardless of the type of splice used (partial penetration grove welded or bolted), shall be acceptable. If the gap exceeds 1.5 mm, and is less than 6 mm, and if an engineering investigation shows that sufficient contact area exists, the gap shall be packed with non tapered steel shims. Shums may be of mild steel, regardless of the grade of the main material.
#### 10.11.3.5 Field Welding
Shop paint on surfaces adjacent to welds shall be wire-brushed to reduce paint film to a minimum.
#### 10.11.3.6 Field Connection
As erection progresses, the work shall be securely bolted or welded to take care of all dead, wind and live load forces.
### 10.11.4 Quality Control
The fabricator shall provide quality control procedures to the extent that all work is performed in accordance with this specification. In addition to the fabricator's quality control procedures, material and workmanship at all times may be subject to inspection by the Engineer.
#### 10.11.4.1 Cooperation
As far as possible, all inspection shall be made at the fabricator's plant. The fabricator shall cooperate with the Engineer permitting access for inspection to all places where work is being done. The Engineer shall schedule his work for minimum interruption to the work of the fabrication.
#### 10.11.4.2 Rejection
Material or workmanship not in reasonable conformance with the provisions of this specification may be rejected at any time during the progress of the work.
#### 10.11.4.3 Inspection of Welding
The inspection of welding shall be performed in accordance with the provisions of Sec 6 of AWS D1.1 – Standard Welding Code Steel.
When nondestructive testing is required, the process, extent and standards of acceptance shall be defined clearly in the design documents.
#### 10.11.4.4 Inspection of Slip-critical High strength Bolted Connections
The inspection of slip-critical, high strength bolted connections shall be in accordance with the provisions of the Specification for Standard Joints Using ASTM A325 or A490 Bolts of Research Council on Structural Connections.
## 10.12 SURFACE TREATMENT
### 10.12.1 General
Surface treatment of steel structures shall include the preparation of surfaces and the application and drying of the paint or galvanization including the protection of the applied treatment against damage.
### 10.12.2 Weather Condition
#### 10.12.2.1 Paints
Paints shall be applied only on thoroughly dry surfaces and during period of favourable weather. Painting shall not be permitted when the atmospheric temperature is at or below 5°C when using vinyl, alkyd, and organic materials, and 10°C when using inorganic zinc, or when the humidity exceeds 85 percent at the site of the work, or when freshly painted surfaces may be damaged by rain, fog, or dew, or when it can be anticipated that the atmospheric temperature will drop below 5°C during the drying period.
#### 10.12.2.2
During inclement weather , painting may be done inside an enclosure with artificially controlled atmospheric dust, or when such painting within limits suitable for painting.
#### 10.12.2.3
All blast cleaning, except that performed within closed buildings, and all painting shall be preferably performed during daylight hours.
### 10.12.3 Cleaning of Surfaces
#### 10.12.3.1
All exposed surfaces of structural steel, except galvanized surfaces, shall be cleaned and painted.
#### 10.12.3.2
All surfaces of new structural steel or surfaces which are to be painted with inorganic zinc shall be blast cleaned.
#### 10.12.3.3
In repainting existing steel structures where partial cleaning is required, the method of cleaning shall be specified. Any damage to sound painted surfaces, on areas not designated for treatment, shall be repaired.
#### 10.12.3.4 Cleaning methods shall conform to the following.
a) Blast Cleaning
i) Abrasives used for blast cleaning shall be either clean dry sand, mineral grit, steel shot, or steel grit, and shall be suitable to produce satisfactory results.
ii) Unwashed beach sand containing salt or excessive amounts of silt shall not be allowed.
iii) All dirt, mill scale, rust, old paint, and other foreign materials shall be removed from steel surfaces by an approved blast cleaning apparatus.
iv) Blast cleaned surfaces shall be primed or treated the same day blast cleaning is done. If cleaned surfaces rust or are contaminated with foreign materials before painting, they shall be re-cleaned.
b) Steam Cleaning
i) All dirt, grease, chalky paint or other foreign materials which may have accumulated on the previously painted or galvanized surfaces shall be removed with a steam cleaning apparatus which shall precede all other phases of cleaning. It is not intended that sound paint be removed by this process. Any paint which becomes loose, curled, lifted, or loses its bond with the preceding coat or coats after steam cleaning, shall be removed to expose sound paint or metal surface.
ii) A detergent shall be added to the feed water of the steam generator. The detergent shall be of such composition and shall be added in such quantity that the cleaning as provided in the above is accomplished.
iii) Any residue, detergent, or other foreign material which may accumulate on cleaned surfaces shall be removed by flushing with fresh water.
iv) Steam cleaning shall not be performed more than two weeks prior to painting.
v) Subsequent painting shall not be performed until the cleaned surfaces are thoroughly dry and in no case less than 24 hours after cleaning.
c) Hand Cleaning
i) Wire brushes, either hand or powered scraping tools, power grinders, or sandpaper shall be used to remove all dirt, loose rust and mill scale, or paint which is not firmly bonded to the metal surfaces.
ii) Pneumatic chipping hammers shall not be used.
### 10.12.4 Application
#### 10.12.4.1
Painting shall be done in a neat and workmanlike manner. Unless otherwise specified, paint shall be applied by brush, spray, roller or any combination thereof peculiar to the paint being applied.
#### 10.12.4.2
Each application of paint shall be thoroughly cured and any skip, thin areas, or other deficiencies corrected before the succeeding application. The surface of the paint being covered shall be free from moisture, dust, grease, or any other deleterious materials that would prevent the bond of the succeeding applications. In spot painting, old paint which lifts after the first application shall be removed by scraping and the area repainted before the next application.
#### 10.12.4.3
Brushes, when used, shall have sufficient body and length of bristle to spread the paint in a uniform film. Paint shall be evenly spread and thoroughly brushed out.
#### 10.12.4.4
Rollers, when used, shall be of a type that does not leave a stippled texture in the paint film.
#### 10.12.4.5
Mechanical mixers shall be used to mix paint. Prior to applying, the paint shall be mixed for a sufficient length of time to thoroughly mix the pigment and vehicle together, and shall be kept thoroughly mixed during its application.
#### 10.12.4.6
Paints shall be formulated ready for application and no thinning will be allowed unless otherwise provided in the application materials specification for the paint being used.
#### 10.12.4.7
The dry film thickness of the paint will be measured in place with a calibrated magnetic film thickness gauge.
#### 10.12.4.8
The thickness of each application shall be limited to that which will result in uniform drying throughout the paint film.
#### 10.12.4.9
Succeeding applications of paint shall be of such shade as to contrast with the paint being covered.
#### 10.12.4.10
Zinc-rich primers shall be applied by spray methods. On areas inaccessible to spray application, the paint may be applied by brush or daubers.
#### 10.12.4.11
Structures shall be blast cleaned and painted with the total thickness of undercoats before erection. After erection and before applying subsequent paint, all areas where paint has been damaged or has deteriorated and all exposed unpainted surfaces shall be thoroughly cleaned and spot painted with undercoats to the specified thickness.
#### 10.12.4.12
Surfaces exposed to the atmosphere and which would be inaccessible for painting after erection shall be painted the full number of applications prior to erection.
#### 10.12.4.13
Unless otherwise specified, steelworks in contact with concrete need not be painted.
#### 10.12.4.14
Surfaces inaccessible after shop assembly shall be cleaned and painted prior to assembly except for contact surfaces.
#### 10.12.4.15
Paint is permitted unconditionally in bearing type connections. For slip-critical connections where the design is based on special faying surface conditions, the surfaces in contact shall not be painted.
#### 10.12.4.16
Unless otherwise specified in the design documents, surfaces within 50 mm of any field weld location shall be free of materials that would prevent proper welding or produce toxic fumes during welding.
### 10.12.5 Protection against Damage
#### 10.12.5.1
Adequate protective measure shall be taken to prevent damage to the work.
#### 10.12.5.2
Paint or paint stains that result in an unsightly appearance on surfaces not designated to be painted shall be removed or obliterated.
#### 10.12.5.3
All painted surfaces that are marred or damaged shall be repaired with materials and to a condition equal to that of the coating specified.
### 10.12.6 Painting Galvanized Surfaces
#### 10.12.6.1
All galvanized surfaces that are to be painted shall first be cleaned by washing with mineral spirit solvent sufficient to remove any oil, grease, or other materials foreign to the galvanized coating.
#### 10.12.6.2
After washing, all areas shall be roughened by abrasive blasting. Galvanizing shall not be removed by this operation.
#### 10.12.6.3
After preparation, all galvanized surfaces that are to be painted shall be covered with one application of zinc dust-zinc oxide primer. The zinc dust-zinc oxide paint shall be applied by spraying to produce a complete covering of the galvanized surfaces.
#### 10.12.6.4
After the application of zinc dust-zinc oxide paint one application of pretreatment, vinyl wash primer shall be applied to such surfaces. The vinyl wash primer shall be applied by spraying to produce uniform wet film on the surface.
## 10.13 DESIGN DOCUMENTS
### 10.13.1 General
This section covers the requirements for presentation of design documents including drawings for construction of steel structures. These requirements shall be met in addition to those specified in Chapter 1, General Design Requirements.
### 10.13.2 Drawings
The design plans shall show a complete design with sizes, sections and relative locations of the various members. The stiffeners and bracings shall also be shown. Floor levels, column centres and offset shall be dimensioned. Drawings shall be drawn to a scale large enough to show the information clearly.
Design documents shall indicate the type or types of construction as defined in Sec 10.4 including the loads and design requirements necessary for preparation of shop drawings, sheets, moments and axial forces to be resisted by all members and their connections.
Where joints are to be assembled with high strength bolts, the design documents shall indicate the connection type (slip-critical, tension or bearing).
Camber of trusses, beams and girders, if required, shall be shown in the design documents.
### 10.13.3 Standard Symbols and Nomenclature
Welding and inspection symbols used on plans and shop drawings shall preferably be the American Welding Society symbols. Other welding symbols may be used, provided a complete explanation thereof is shown in the design documents.
### 10.13.4 Notation for Welding
Notes shall be made in the design documents and on the shop drawings of those points or groups of joints in which the welding sequence and technique of welding shall be carefully controlled to minimize distortion. Weld lengths called for in the design documents and on the shop drawings shall be the net effective lengths.
## Related Appendix
**Appendix A** Conversion of Expressions from SI to FPS Units
# Chapter 11: Timber Structures
Source: https://docs.sayed.app/bnbc2006/part-6-structural-design/chapter-11-timber-structures
## 11.1 Scope
This section of the Code provides minimum requirements for the design and construction of timber structures.
## 11.2 Notation
Unless otherwise explicitly stated, the following units shall be implicit for the corresponding quantities in the design and other expressions provided in this chapter.
| Unit | Symbol |
| ----------------- | ------ |
| Length | mm |
| Area | mm² |
| Moment of inertia | mm⁴ |
| Force | N |
| Moment, torsion | N·mm |
| Stress, strength | N/mm² |
**Symbols:**
| Symbol | Definition |
| ------------------------------- | ------------------------------------------------------------------------------------------------------- |
| b | width of beam |
| C\_r | restraint factor for spaced column |
| D | depth of beam |
| D\_1 | depth of beam at notch |
| d | least dimension of column |
| d\_1 | least overall width of box column |
| d\_2 | least overall dimension of core in box column |
| E | modulus of elasticity in bending |
| f\_bk | calculated bending stress in extreme fibre |
| f\_pc | calculated average axial compressive stress |
| f\_pt | calculated axial tensile stress |
| f\_pp | permissible bending stress on the extreme fibre |
| f\_pc | permissible stress in axial compression |
| f\_pn | permissible stress in axial compression normal to grain |
| f\_pp | permissible stress in compression parallel to grain |
| K, K\_s, K\_3, K\_4, K\_5, K\_6 | form factors |
| K\_7 | modification factor for bearing stress |
| K\_8 | constant equal to 0.671 $\sqrt{\frac{E}{f_{pp}}}$ |
| K\_9 | constant equal to $\frac{\pi}{2}\sqrt{\frac{UE}{5f_{pp}}}$ |
| K\_ | constant equal to 0.671 $\sqrt{\frac{C_r E}{f_{pp}}}$ |
| ℓ | span of a beam or truss |
| φ | shank diameter of the nail or bolt |
| p\_1 | ratio of the thickness of the compression flange to the depth of the beam |
| Q | moment of area above or below the neutral axis about neutral axis, mm³ |
| θ\_1 | ratio of the total thickness of web or webs to the overall width of the beam |
| S | effective length of solid and box columns; distance between points of lateral support of spaced columns |
| t | nominal thickness of planks |
| U | constant for a particular thickness of the plank, See K\_9 and Sec 11.7.3(e) |
| V | vertical reaction or shear at a section |
| Y | a factor determining the value of form factor K\_4, See Sec 11.6.3.1(c)(ii) |
| θ | angle of load to grain direction |
## 11.3 Terminology
This section provides an alphabetical list of the terms used in this chapter of the Code. In case of any conflict or contradiction between a definition given in this section and that in Part 1, the meaning provided in this section shall govern for interpretation of the provisions of this chapter.
### 11.3.1 Structural Purpose Definitions
**BASIC OR ULTIMATE STRESS:** The stress which is determined on small clear specimen of timber, and does not take into account the effect of naturally occurring phenomenon and other factors.
**LOCATION:** Location is generally referred to as exact position where a timber is used.
**INSIDE LOCATION:** Locations in structures where timber remain continuously dry and protected from weather, such as inside a building.
**OUTSIDE LOCATION:** Locations in structures where timber is occasionally subject to wetting and drying such as open sheds and outdoor structures.
**WET LOCATION:** Locations in structures where timber is almost continuously damp or wet due to contact with the earth or water, such as pile and timber foundation.
**PERMISSIBLE STRESS:** The basic stress as modified by modification factors according to defects, locations and particulars of design.
**SPACED COLUMN:** Two or more individual members with their longitudinal axis parallel, separated at the ends and middle points by blocking and joined at the ends by timber connectors capable of developing required shear resistance.
### 11.3.2 Definitions of Defects in Timber
**CHECK:** A separation of fibres extending along the grain which is confined to one face of a piece of timber.
**COMPRESSION WOOD:** Abnormal wood formed on the lower sides of branches and inclined stems of coniferous trees. It is darker and harder than normal wood but relatively low in strength for its weight. It can be usually identified by wide eccentric growth rings with abnormally high proportion of growth latewood.
**DEAD KNOT:** A knot in which the layers of annual growth are not completely intergrown with those of the adjacent wood. It is surrounded by pitch or bark. The encasement may be partial or complete.
**DECAY OR ROT:** Disintegration of wood tissues caused by wood destroying fungi or other micro-organisms.
**DECAYED KNOT:** A knot softer than the surrounding wood and containing decay.
**DIAMETER OF KNOT:** The maximum distance between the two points farthest apart on the periphery of a round knot, on the face on which it becomes visible. In the case of a spike or a splay knot, the maximum width of the knot visible on the face on which it appears shall be taken as its diameter.
**DISCOLORATION:** A change from the normal colour of the wood which does not impair the strength of the wood.
**KNOT:** A branch base or limb embedded in the tree by natural growth.
**KNOT HOLE:** A hole left in the timber due to the removal of a knot.
**LIVE KNOT:** A knot free from decay and other defects, in which the fibres are firmly intergrown with those of the surrounding wood.
**LOG:** An unhewn piece of felled tree or similar mass of wood.
**LOOSE GRAIN:** A defect on a flat swan surface caused by the separation or raising of wood fibres along the growth rings.
**LOOSE KNOT:** A knot that is not held firmly in place by growth and that cannot be relied upon to remain in place.
**MOULD:** A soft vegetative growth that forms on wood in damp and stagnant atmosphere. It is the least harmful type of fungus, usually confined to the surface of the wood.
**PITCH POCKET:** Accumulation of resin between growth rings of coniferous wood as seen on the cross-section.
**SAP STAIN:** Discoloration of the sapwood mainly due to fungi.
**SAPWOOD:** The outer layer of log, which contains living cells and food material in the growing trees. The sapwood is usually lighter in colour and is readily attacked by insects and fungi.
**SHAKE:** A partial or complete separation between adjoining layers of tissues as seen in end surfaces.
**SLOPE OF GRAIN:** The inclination of the fibres to the longitudinal axis of the member.
**SOUND KNOT:** A tight knot solid across its face, free from decay and at least as hard as the surrounding wood.
**SPLIT:** A crack extending from one face to another that runs along the grain of a piece of wood.
**TIGHT KNOT:** A knot so held by growth or position as to remain firm in position in the piece of wood.
**WANE:** The original rounded surface of a tree remaining on a piece of converted timber.
**WARP:** A deviation in sawn timber from a true plane surface or distortion due to stresses causing departure from a true plane.
**WORM HOLES:** Cavities caused by worms.
## 11.4 Materials
### 11.4.1
The species of timber recommended for structural purpose with their engineering characteristics are given in Table 6.11.1.
| Standard Trade Name | Local Name | Botanical Name | Average Weight and Range of Weights at 12% Moisture Content (kN/cubic metre) | Durability | Treatability | Refractoriness to Air Seasoning | Group | Permissible Lateral Strength of Nail in Double Shear (kN) |
| ------------------- | -------------------------------------------------- | ----------------------- | ---------------------------------------------------------------------------- | ---------- | ------------ | ------------------------------- | ----- | --------------------------------------------------------- |
| Babla | Babla, Babul | Acacia nilotica | 7.80 (7.50-8.50) | HD | T | MR | A | 1.50 (1.10) 2.75 (1.35) |
| Banderhold | Banderhold, Kacha, Lampati, Ramdalu, Kandala Jarul | Duabanga sonneratioides | 4.75 (4.45-5.10) | MD | ET | MR | B | - |
| Bhadi | Sil Bhadi, Kapila | Garuga pann ata | 7.30 (6.80-7.80) | D | VHT | - | - | - |
| Bhadi | Kairijal Bhadi | Bischola javanica | 6.70 (5.50-7.10) | D | VHT | - | - | - |
| Boilam | Boilam | Anisoptera glabra | 5.60 (4.80-6.20) | D | T | - | - | - |
| Chapalish | Chapalish, Cham Chambal, Chram | Artocarpus chaplasha | 5.25 (4.00-6.80) | HD | T | MR | B | - |
| Champa | Champa-ful Champasundi, Champa Teak Chambal | Michelia champaca | 6.30 (4.80-7.00) | - | - | MR | A | - |
| Chickrassi | Chickrassi, Chabarassi, Chittagaong Wood | Chickrassia tabidaris | 6.40 (4.80-8.15) | HD | VHT | MR | A | - |
| Civit | Civit, Amchundul | Swintonia floribunda | 6.50 (4.80-7.70) | ND | ET | LR | A | - |
| Dakroom | Dakroom, Rangkat Bhati Awal | Mitragynaparvifolia | 6.70 (5.50-7.20) | - | - | HR | A | - |
| Gamar | Gamar, Gamar, Joginichakra, Gamber | Gmelina arborea | 4.70 (4.00-5.90) | HD | VHT | MR | B | - |
| Garjan | Garjan, Dhuliya garjan, Dholi garjan | Dipterocarpusalatus | 7.05 (6.00-8.00) | D | ET | MR | A | 1.90 (0.90) 1.95 (0.95) |
| Goran | Goran | Gerisops roxburghiana | 8.50 (6.90-9.40) | - | - | - | - | - |
| Jarul | Jarul, Sidha jarul | Lagerstromeria Spp. | 6.40 (5.00-8.10) | MD | VHT | MR | A | - |
| Jam | Dhakijam, Nalijam | Syzygium Spp. | 8.05 (7.00-9.90) | MD | VHT | HR | B | - |
| Kanthal | Kanthal | Artocarpus integrifolia | 5.25 (4.00-7.50) | D | MT | MR | B | - |
| Kankra | Kankra, Ntinga | Bruguiera conjugata | 8.60 (7.70-9.50) | - | - | HR | A | - |
| Lali | Lali | Amoora wallichii | 5.70 (4.80-6.50) | - | - | - | - | - |
| Lohakat | Lohakat, Pyinkado | Xylia dolabriformis | 9.85 (8.20-1.000) | - | - | - | - | - |
| Minjiri | Minjiri | Cassia siamea | 6.80 (5.00-7.10) | - | - | - | - | - |
| Neem | Neem | Azadirachta indica | 6.60 (6.20-7.00) | MD | VHT | MR | A | - |
| Passur | Passur, Ail | Xylocarpus moluccensis | 7.40 (6.50-8.00) | - | - | MR | A | - |
| Pitraj | Pitraj, Rata, Rohini, Raina, Awpata, Okeyeng | Aphenamixis polystachya | 5.70 (4.65-6.40) | MD | VHT | MR | B | - |
| Sal | Sal, gajari | Shorea robusta | 8.70 (6.75-10.50) | HD | VHT | HR | A | 2.30 (1.15) 3.05 (2.00) |
| Sissoo | Sissoo | Dalbergia sissoo | 7.90 (7.45-8.55) | - | - | MR | A | 1.7 (1.5) |
| Sonalu | Sonalu, Banderathi | Cassia fistula | 5.60 (4.80-6.10) | - | - | - | - | - |
| Sundri | Sundri | Seritera formes | 10.50 (9.20-11.00) | D | T | MR | A | - |
| Tali | Tali, Lali, Kurta, Dudha | Palaquium Polyanthum | 6.90 (610-880) | HD | VHT | MR | A | - |
| Teak | Teak, Shegun, Sakkan | Tectena grandis | 6.60 (5.30-8.15) | HD | HT | MR | A | 1.45 (0.00) 2.80 (1.30) |
| Telsur | Telsur, Tersol | Hopea odorata | 6.95 (5.95-7.15) | D | ET | MR | A | - |
| Toon | Toon, Surij, Surujbed, Serbet, Kuma Poma | Cedrela toona | 4.80 (3.70-5.95) | HD | VHT | LR | B | 1.00 (0.80) 0.90 (0.40) |
**Note:**
**Durability**
* HD - Highly durable: Life more than 36 months
* D - Durable: Life 25-36 months
* MD - Moderately durable: Life 10-25 months
* ND - Nondurable: Life upto 10 months
**Treatability**
* ET - Easily treatable, penetration more than 40 mm, absorption above 120 kg/m³
* T - Treatable, penetration range 20 - 40 mm, absorption range 80 - 128 kg/m³
* MT - Moderately treatable, penetration range 10 - 20 mm, absorption range 48 - 80 kg/m³
* VHT - Very hard to treat, absorption below 48 kg/m³
**Refractoriness to Air Seasoning**
* HR - Highly refractory
* MR - Moderately refractory
* LR - Less refractory
\*\*Permissible lateral strength (in double shear) of 3.55 mm ϕ nails 80 mm long and 5 mm ϕ nails 150 mm long at lengthening joints and node joints (values in bracket are for node joints). The values shown in italics refer to 5 mm ϕ nails. The space marked "-" indicates that information is lacking.
### 11.4.2
The general characteristics like durability and treatability of the species of timber are also given in Table 6.11.1. Species other than those recommended in Table 6.11.1 may be allowed, provided basic stress characteristics are determined.
**Note:** For obtaining basic stress figures of the unlisted species, reference may be made to Forest Research Institute, Chittagong.
### 11.4.3
The moisture content of timber for various positions in buildings shall be as given in Table 6.11.2.
| Structural Elements | Percentage Moisture Content |
| ------------------- | --------------------------- |
| Doors and Windows | 16 |
| Other Elements | 20 |
### 11.4.4 Sawn Timber
#### 11.4.4.1 Sizes
Preferred cut sizes of timber for use in structural components shall be as given in Tables 6.11.3, 6.11.4 and 6.11.5.
**Table 6.11.3: Preferred Cut Sizes of Structural Timber for Roof Trusses (From 3 to 20 Metres)**
\| Thickness (mm) | Width (mm) |||||||||
\|---|---|---|---|---|---|---|---|---|
\| | 40 | 50 | 60 | 80 | - | - | - |
\| 20 | 40 | 50 | 60 | 80 | 100 | 120 | 140 | 160 |
\| 25 | 40 | 50 | 60 | 80 | 100 | 120 | 140 | 160 |
\| 30 | 40 | 50 | 60 | 80 | 100 | 120 | 140 | 160 |
\| 40 | - | - | 60 | 80 | 100 | 120 | 140 | 160 |
\| 50 | - | - | 60 | 80 | 100 | 120 | 140 | 160 |
\| 60 | - | - | - | 80 | 100 | 120 | 140 | 160 |
\| 80 | - | - | - | - | 100 | 120 | 140 | 160 |
Note: Preferred lengths of timber: 1 m, 1.5 m, 2 m, 2.5 m and 3 m.
**Table 6.11.4: Preferred Cut Sizes of Structural Timber for Roof Purlins, Rafters, Floor Beams, etc.**
\| Thickness (mm) | Width (mm) ||||||||||
\|---|---|---|---|---|---|---|---|---|
\| | 80 | 100 | 120 | 140 | 160 | - | - |
\| 60 | 80 | 100 | 120 | 140 | 160 | - | - |
\| 80 | - | 100 | 120 | 140 | 160 | - | - |
\| 100 | - | - | - | 140 | 160 | 180 | 200 |
Note: Preferred lengths of timber: 2 m, 2.5 m, 3 m and 3.5 m.
**Table 6.11.5: Preferred Cut Sizes of Structural Timber for Partition Framing and Covering**
\| Thickness (mm) | Width (mm) ||||||||||||
\|---|---|---|---|---|---|---|---|---|---|---|
\| | - | 50 | - | 80 | - | - | - | - |
\| 10 | - | 50 | - | 80 | 100 | 120 | 160 | - | - |
\| 15 | - | 50 | - | 80 | 100 | 120 | 160 | - | - |
\| 20 | - | 50 | - | 80 | 100 | 120 | 160 | 200 | 240 |
\| 25 | - | - | - | 80 | 100 | 120 | 160 | 200 | 240 |
\| 30 | - | - | - | 80 | 100 | 120 | 160 | 200 | 240 |
\| 40 | 40 | 50 | 60 | 80 | 100 | 120 | 160 | 200 | 240 |
\| 50 | 40 | 50 | 60 | 80 | 100 | 120 | 160 | 200 | 240 |
\| 60 | - | - | - | - | 100 | 120 | 160 | 200 | 240 |
\| 80 | - | - | - | - | 100 | 120 | 160 | 200 | 240 |
Note: Preferred lengths of timber: 0.5 m, 1 m, 1.5 m, and 2 m.
#### 11.4.4.2 Tolerances
Permissible tolerance in measurements of cut sizes of structural timber shall be as follows:
**a) For width and thickness:**
1. Up to and including 100 mm: +3 mm, -0 mm
2. Above 100 mm: +6 mm, -3 mm
**b) For length:** +10 mm, -0 mm
### 11.4.5 Grading of Structural Timber
#### 11.4.5.1
Based on the permissible defects given in Table 6.11.6, cut sizes of structural timber shall be graded as i) Grade 1, ii) Grade 2 and iii) Grade 3 after seasoning.
#### 11.4.5.2
The following defects shall apply to structural timber.
**a) Prohibited Defects:** Loose grains, splits, compressive wood in coniferous timber, heartwood rot, sap rot, warp, worm holes made by powder post beetles and pitch pockets shall not be permitted.
**b) Permissible Defects:** Defects specified in Table 6.11.6 shall be permissible.
**c) Location of Defects:** The influence of defects in timber is different for different location in the structural element. During construction these should be so placed that they do not have any adverse effect on the members.
**Table 6.11.6: Permissible Defects for Cut Sizes of Timber for Structural Use (All dimensions are in mm)**
| Defects | Grade 1 | Grade 2 | Grade 3 | | | | |
| --------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------- | ------------------------------------------------ | -------------------------------------------- | ------------------------------------------------ | -------------------------------------------- |
| **i) Wane** | Shall be permissible at its deepest portion up to a limit of 1/4 of the width of the surface on which it occurs. | Shall be permissible at its deepest portion up to a limit of 1/3 of the width of the surface on which it occurs | Shall be permissible at its deepest portion up to a limit of 1/3 of the width of the surface on which it occurs | | | | |
| **ii) Worm holes** | Other than those due to powder post beetles are permissible. | Other then those due to post beetles are permissible | Other than those due to powder post beetles are permissible | | | | |
| **iii) Slope of grain** | Shall not be more than 1 in 20 | Shall not be more than 1 in 15 | Shall not be more than 1 in 12 | | | | |
| **iv) Live knots: Widths of wide faces of cut sizes of timber** | | Permissible Maximum Size of Live Knot on | | | | | |
| | | Narrow faces and 1/3 of the faces close to edges | The remaining central half of the wide faces | Narrow faces and 1/3 of the faces close to edges | The remaining central half of the wide faces | Narrow faces and 1/3 of the faces close to edges | The remaining central half of the wide faces |
| | 75 | 10 | 10 | 19 | 19 | 29 | 30 |
| | 100 | 13 | 13 | 25 | 25 | 38 | 39 |
| | 150 | 19 | 19 | 38 | 38 | 57 | 57 |
| | 200 | 25 | 25 | 44 | 50 | 66 | 75 |
| | 250 | 25 | 25 | 50 | 57 | 75 | 87 |
| | 300 | 27 | 38 | 54 | 72 | 81 | 123 |
| | 350 | 29 | 41 | 57 | 81 | 87 | 123 |
| | 400 | 32 | 41 | 63 | 87 | 96 | 132 |
| | 450 | 33 | 47 | 66 | 93 | 99 | 141 |
| | 500 | 35 | 50 | 69 | 100 | 105 | 150 |
| | 550 | 36 | 52 | 72 | 103 | 108 | 156 |
| | 600 | 38 | 53 | 75 | 106 | 114 | 159 |
| **v) Checks and shakes:** | | Permissible Depth (Max.) | | | | | |
| Face or width of the timber | | | | | | | |
| 75 | 12 | 25 | 36 | | | | |
| 100 | 18 | 35 | 54 | | | | |
| 150 | 25 | 50 | 75 | | | | |
| 200 | 33 | 65 | 99 | | | | |
| 250 | 40 | 81 | 120 | | | | |
| 300 | 50 | 100 | 150 | | | | |
| 350 | 57 | 115 | 171 | | | | |
| 400 | 66 | 131 | 198 | | | | |
| 450 | 76 | 150 | 225 | | | | |
| 500 | 83 | 165 | 270 | | | | |
| 550 | 90 | 181 | 300 | | | | |
| 600 | 100 | 200 | - | | | | |
## 11.5 Permissible Stresses
### 11.5.1 Basic Permissible Stress
**a)** The permissible stresses for Grade 2 structural timber for different locations shall be as given in Table 6.11.7, provided that the following conditions are satisfied:
**Table 6.11.7: Permissible Stress for Grade 2 Timber**
| Stress | Location | Permissible Stress\* N/mm² Group A (E=10.0-12.5) | Permissible Stress\* N/mm² Group B (E=5.5-10.0) |
| ---------------------------------- | ----------------------------- | ------------------------------------------------ | ----------------------------------------------- |
| Bending and tension along grain | Inside location | 12.3 | 8.4 |
| | Outside locations | 10.2 | 7.0 |
| | Wet locations | 8.1 | 6.0 |
| Shear | Horizontal, all locations\*\* | 0.9 | 0.6 |
| | Along grain, all locations | 1.3 | 0.9 |
| Compression parallel to grain | Inside locations | 7.0 | 6.4 |
| | Outside locations | 6.3 | 5.6 |
| | Wet locations | 5.8 | 4.6 |
| Compression perpendicular to grain | Inside locations | 2.2 | 2.2 |
| | Outside locations | 1.8 | 1.7 |
| | Wet locations | 1.5 | 1.4 |
\* Whenever earthquake or wind forces are considered along with other normal design forces, the permissible stresses in material may be increased by 33%.
\*\* The values of horizontal shears to be used only for beams. In all other cases shear along grain to be used.
i) The timber shall be of high or moderate durability and be given suitable treatment where necessary. If the location is inside and not in contact with the ground, low durability timber may be used after proper seasoning and preservative treatment given in accordance with BDS 819.
ii) The loads shall be continuous and permanent.
iii) Whenever earthquake or wind forces are considered along with other normal design forces, the permissible stresses in material may be increased by 33%.
**b)** For other grades of timber, the permissible stresses given in Table 6.11.7 shall be multiplied by the following factors to obtain the permissible stresses assuming that the conditions stipulated in Sec 11.5.1(a) are satisfied:
i) Grade 1: 1.16
ii) Grade 3: 0.84
**c)** For low durability timber to be used on outside locations, the permissible stresses obtained from Sec 11.5.1 and 11.5.2 shall be multiplied by 0.8.
### 11.5.2 Modification Factors for Permissible Stresses
#### 11.5.2.1 Change in Slope of Grain
When the timber has not been graded due to change in slope of grain and has major defects like slope of grain, knots and checks or shakes but the slopes and defects are within permissible value, the permissible stress given in Table 6.11.7 shall be multiplied by modification factor K₁ for different slopes of grain as given in Table 6.11.8.
#### 11.5.2.2 Change in Duration of Load
For different duration of design load the permissible stresses given in Table 6.11.7 shall be multiplied by the modification value, the modification factor K₂ given in Table 6.11.9.
**Table 6.11.8: Modification Factor K₁ to Allow for Change in Slope of Grain**
| Slope | Modification Factor K₁ | |
| --------- | ---------------------- | ---------------- |
| | Beams, Joists and Ties | Posts or Columns |
| 1 in 10 | 0.80 | 0.74 |
| 1 in 12 | 0.90 | 0.82 |
| 1 in 14 | 0.98 | 0.87 |
| ≤ 1 in 15 | 1.00 | 1.00 |
**Table 6.11.9: Modification Factor K₂ for Change in Duration of Loading**
| Duration of Loading | Modification Factor K₂ |
| ----------------------- | ---------------------- |
| Continuous | 1.00 |
| Two months | 1.15 |
| Seven days | 1.25 |
| Wind and earthquake | 1.33 |
| Instantaneous or impact | 2.00 |
## 11.6 Beams
### 11.6.1 Design Consideration
All structural members in a building shall be capable of sustaining the worst combination of all loadings (see Sec 11.6.2) without exceeding the limits of specified allowable stress.
### 11.6.2 Loads
The loads and their combination shall conform to those given in Chapter 2, Loads.
### 11.6.3 Solid Beams
#### 11.6.3.1 Definitions
**a) Net Section**
i) The net section is obtained by deducting from the gross section the projected area of all material removed by boring, grooving or other means.
ii) The net section used in calculating load carrying capacity of a member shall be the least net section determined as above by passing a plane or series of connected planes transversely through the members.
iii) Notches shall in no case remove more than one quarter of the section.
**b) Effective Span:** The effective span of beams shall be taken as the distance from face of supports plus one-half of the required length of bearing at each end. For continuous beams the span may be measured from centre of bearing at the supports over which the beam is continuous.
**c) Form Factors:** The following form factors shall be applied to the bending stress:
i) **Rectangular Section:** For rectangular sections of different depth, the form factor K₃ shall be taken as:
$$
K_3 = 0.81\left[\frac{D^2 + 89400}{D^2 + 55000}\right]
$$
(11.6.1)
For beams having depth less than or equal to 300 mm, form factor K₃ shall not be applicable.
ii) **Box Beam and I-Beams:** For box beams and I-beams form factor K₄ shall be obtained by using the following formula
$$
K_4 = 0.8 + 0.8Y\left[\frac{D^2 + 89400}{D^2 + 55000} - 1\right]
$$
(11.6.2)
where,
$$
Y = p_1^2(6 - 8p_1 + 3p_1^2)(1 - q_1) + q_1
$$
iii) **Solid Circular Cross-Sections:** The form factor K₅ shall be taken as 1.18 for solid circular cross-sections.
iv) **Square Cross-Sections:** The form factor K₆ shall be taken as 1.41 for square cross-sections where the load is in the direction of diagonal.
v) **Width:** The minimum width of flexural member shall be 50 mm or one-fiftieth of the span whichever is greater.
vi) **Depth:** The depth of flexural member shall not be taken more than three times its width without lateral stiffening.
vii) **Stiffening:** Flexural members having a depth exceeding three times its width or a span exceeding 50 times its width or both shall be laterally restrained at a distance not exceeding 50 times its width to control twisting or buckling.
viii) **Deflection:** The deflection for flexural members (except nail laminated beams) supporting brittle materials like gypsum ceilings, slates, tiles and asbestos sheets shall not exceed ℓ/360. The deflection in the case of other flexural members shall not exceed ℓ/240 and in the case of cantilevers ℓ/180.
#### 11.6.3.2 Shear
**a)** The following formula shall apply:
i) General formula:
$$
H = \frac{VQ}{Ib}
$$
(11.6.3)
ii) Rectangular beams:
$$
H = \frac{3V}{2bD}
$$
(11.6.4)
iii) Notched beams with tension notches and supports
$$
H = \frac{3VD}{2bD_1^2}
$$
(11.6.5)
(See Sec 11.6.3.2(c))
**b)** In determining the vertical reaction V, the following deduction in loads may be made:
i) The critical section shall be at a distance d from the face of the support.
ii) All concentrated loads in the vicinity of the supports may be reduced by the reduction factor applicable according to Table 6.11.10.
**Table 6.11.10: Reduction Factor for Concentrated Loads in the Vicinity of Supports**
| Distance of load from the nearest support | 1.5D or less | 2D | 2.5D | 3D or more |
| ----------------------------------------- | ------------ | --- | ---- | ------------ |
| Reduction factor | 0.6 | 0.4 | 0.2 | No reduction |
Note: For intermediate distances, percentage reduction may be obtained by linear interpolation.
**c)** Unless the local stress is calculated and found to be within the permissible stress, flexural member shall not be cut, notched or bored except as follows:
i) Notches may be cut in the top or bottom of the beam neither deeper than D/5 nor farther than ℓ/6 from the edge of the support.
ii) Hole not larger in diameter than D/4 may be bored in the middle third of the depth and length, and
iii) If holes or notches are positioned at a distance greater than 3D from the face of the nearest support, the net remaining depth shall be used in determining the bending strength.
#### 11.6.3.3 Bearing
The ends of flexural members shall be supported in recesses which provide adequate ventilation to prevent dry rot and shall not be enclosed. Flexural members except nail laminated beams supported directly on masonry or concrete shall have a length of bearing not less than 75 mm. Members supported on corbels, offsets and roof timbers on a wall shall bear immediately on and be fixed to wall plate not less than 75 mm × 40 mm in size.
Timber joists or floor planks shall not be supported on the top flange of steel beams unless the bearing stress, calculated on the net bearing as shaped to fit the beam, is less than the permissible compressive stress perpendicular to the grain f\_pp specified in Table 6.11.7.
i) **Length and position of bearings:** At any bearing on the side of the grain of timber, the permissible stress in compression perpendicular to grain, f\_pn is dependent on the length and position of bearing.
j) The permissible stresses given in Table 6.11.7 for compression perpendicular to the grain are also the permissible stresses for bearing of any length at the end of a member and for bearing 150 mm or more in length at any other position.
k) For bearing less than 150 mm in length located 75 mm or more from the end of a member as shown in Fig 6.11.1 the permissible stress may be multiplied by the modification factor K₇ given in Table 6.11.11.
![Fig. 6.11.1 Position of End Bearings]()
**Table 6.11.11: Modification Factor K₇ for Bearing Stresses**
| Length of bearing, mm | 15 | 25 | 40 | 50 | 75 | 100 | 150 or more |
| ----------------------- | ---- | ---- | ---- | --- | ---- | --- | ----------- |
| Modification factor, K₇ | 1.67 | 1.40 | 1.25 | 1.2 | 1.13 | 1.1 | 1.0 |
l) No allowance need be made for the difference in intensity of the bearing stress due to bending of a beam.
m) The bearing area should be calculated as the net area after allowance for the amount of wane as permitted in Table 6.11.6.
n) For bearing stress under a washer or a small plate, the same coefficient specified in Table 6.11.11 may be taken for a bearing with a length equal to the diameter of the washer or the width of the small plate.
o) When the direction of the stress is at an angle to the direction of the grain in any structural member, the permissible bearing stress in that member shall be calculated by the following formula.
$$
f_{pp} = \frac{f_{pp}/f_{pn}}{f_{pp}\sin^2\theta + f_{pn}\cos^2\theta}
$$
(11.6.6)
### 11.6.4 Nail Laminated Beams
#### 11.6.4.1 Method of Arrangement
The beam is made up of 20 to 30 mm thick planks placed vertically with joints staggered in the adjoining planks with a minimum distance of 300 mm. The planks are laminated with the help of wire nails at regular intervals to take up horizontal shear developed in the beam besides keeping the planks in position (see Fig 6.11.2).
![Fig. 6.11.2 Typical Nail Laminated Timber Beam]()
#### 11.6.4.2 Sizes of Planks and Beams
**a)** The recommended thickness of planks for fabrication of nail laminated beams are 20 mm, 25 mm and 30 mm.
**b)** In case of nail laminated timber beams, the maximum depth and length of planks shall be limited to 250 mm and 2000 mm respectively.
#### 11.6.4.3 Design Considerations
**a)** The provisions of Sec 11.6.1 through 11.6.3 shall also be applicable to the design of nail laminated beams.
**b)** Permissible lateral strength of mild steel wire nails shall be as given in Table 6.11.1 which shall apply to nails that have their points cut flush with the faces. For nails clenched across the grains, the strength may be increased by 20 percent.
**Table 6.11.12: Number and Size of Planks and Nails for Nail Laminated Beams**
| Overall Width of Beam (mm) | No. of Planks | Thickness of each Plank (mm) | Size of Nails | |
| -------------------------- | ------------- | ---------------------------- | ------------- | -------- |
| | | | Length (mm) | Dia (mm) |
| 50 | 2 | 25 | 80 | 3.55 |
| 60 | 3 | 20 | 80 | 3.55 |
| 70 | 3 | 2 × 25 and 1 × 20 | 100 | 4 |
| 80 | 4 | 20 | 100 | 4 |
| 90 | 5 | 20 | 100 | 4 |
| 100 | 3 | 3 × 30 and 1 × 20 | 125 | 5 |
| 110 | 4 | 3 × 30 and 1 × 20 | 125 | 5 |
| 120 | 4 | 30 | 150 | 5 |
| 150 | 5 | 30 | 150 | 5 |
Note: A number of combinations of different thickness of planks may be adopted as long as the minimum and maximum thickness of planks are adhered to.
#### 11.6.4.4 Deflection
The deflection in the case of nail laminated timber beams, joists, purlins, battens and other flexural members supporting brittle materials like gypsum, tiles and asbestos sheets shall not exceed ℓ/480. The deflection in the case of other flexural members shall not exceed ℓ/360 of the span in the case of beams and joists, and ℓ/225 in the case of cantilevers.
#### 11.6.4.5 Arrangement of Nails
**a)** A minimum number of four nails in a vertical row at regular interval not exceeding 75 mm shall be used to take up horizontal shear as well as to keep the planks in position. This interval may, however, be limited to 50 mm instead of 75 mm near the joints of the planks.
**b)** Shear shall be calculated at various points of the beam and the number of nails required shall be accommodated within the distance equal to the depth of the beam, with a minimum of 4 nails in a row at a standard spacing as shown in Fig 6.11.3.
![Fig. 6.11.3 Standard Lengthwise Spacing in Nail Laminated Beam]()
**c)** If the depth of the beam is more, then the vertical intermediate spacing of nails may be increased proportionately.
**d)** If the nails required at a point are more than that can be accommodated in a row, then these shall be provided lengthwise of the beam within the distance equal to the depth of the beam at standard lengthwise spacing.
**e)** For nailed laminated beam minimum depth of 80 mm for 3.55 mm and 4 mm diameter nails, and 125 mm for 5 mm diameter nails shall be provided.
## 11.7 Columns
### 11.7.1 Design Consideration
**a)** The formulae given for columns are for pin-ended condition and they should be modified according to the value of the K\_e as given in Table 6.11.13.
**Table 6.11.13: Values of Design Buckling Factor, K\_e for Different End Conditions (S = ℓK\_e)**
| Support Condition | One End | Other End | K\_e | |
| ----------------- | ----------- | --------- | ----------- | ---- |
| Rotation | Translation | Rotation | Translation | |
| Fixed | Fixed | Fixed | Fixed | 0.65 |
| Fixed | Fixed | Free | Fixed | 0.8 |
| Free | Fixed | Free | Fixed | 1.0 |
| Fixed | Fixed | Fixed | Free | 1.2 |
| Fixed | Free | Free | Free | 2.1 |
| Free | Fixed | Fixed | Free | 2.4 |
**b)** In the design of an intermediate or long column, gross section shall be used in calculating load carrying capacity of the column.
### 11.7.2 Solid Columns
Solid columns shall be classified into short, intermediate and long columns depending upon their slenderness ratio (S/d) as follows:
i) Short columns are those where S/d \< 11
ii) Intermediate columns are those where 11 ≤ S/d ≤ K\_8
iii) Long columns are those where S/d > K\_8
**a)** For short columns, the permissible compressive stress f\_pc shall be
$$
f_{pc} = f_{pp}
$$
(11.7.1)
**b)** For intermediate columns the permissible compressive stress f\_pc shall be:
$$
f_{pc} = f_{pp}\left[1 - \frac{1}{3}\left(\frac{S}{K_8d}\right)^4\right]
$$
(11.7.2)
**c)** For long columns, the permissible compressive stress f\_pc shall be:
$$
f_{pc} = \frac{0.30E}{\left(\frac{S}{d}\right)^2}
$$
(11.7.3)
**d)** In case of solid columns S/d ratio shall not exceed 50.
**e)** The permissible load on a column of circular cross-section shall not exceed that permitted for a square column of an equivalent cross-sectional area.
### 11.7.3 Built-up Columns - Box Columns
**a)** Box columns shall be classified into short, intermediate and long columns as follows:
i) Short columns are those where
$$
\frac{S}{\sqrt{d_1^2 + d_2^2}} < 8
$$
ii) Intermediate columns are those where
$$
8 \leq \frac{S}{\sqrt{d_1^2 + d_2^2}} \leq K_9
$$
and
iii) Long columns are those where
$$
\frac{S}{\sqrt{d_1^2 + d_2^2}} > K_9
$$
**b)** For short columns, the permissible compressive stress f\_pc shall be:
$$
f_{pc} = f_{pp}
$$
(11.7.4)
**c)** For intermediate columns, the permissible compressive stress f\_pc shall be:
$$
f_{pc} = f_{pp}\left[1 - \frac{1}{3}\left(\frac{S}{K_9\sqrt{d_1^2 + d_2^2}}\right)^4\right]
$$
(11.7.5)
**d)** For long columns, the permissible compressive stress f\_pc shall be:
$$
f_{pc} = \frac{0.30UE}{\left(\frac{S}{\sqrt{d_1^2 + d_2^2}}\right)^2}
$$
(11.7.6)
**e)** The following values of U which depend upon plank thickness t shall be used in (d) above
| t (mm) | U |
| ------ | ---- |
| 25 | 0.80 |
| 50 | 0.60 |
### 11.7.4 Built-up Columns - Spaced Columns
The following formula shall be applicable to spaced columns.
**a)** For short columns, the permissible compressive stress f\_pc shall be:
$$
f_{pc} = f_{pp}
$$
(11.7.7)
**b)** For intermediate columns the permissible compressive stress shall be
$$
f_{pc} = f_{pp}\left[1 - \frac{1}{3}\left(\frac{S}{K_{10}d}\right)^4\right]
$$
(11.7.8)
**c)** For long columns the permissible compressive stress f\_pc shall be:
$$
f_{pc} = \frac{0.30C_rE}{\left(\frac{S}{d}\right)^2}
$$
(11.7.9)
Where the restraint factor C\_r shall be determined according to case (i) or case (ii) as explained below and shown in Fig 6.11.4.
![Fig. 6.11.4 Spaced Column, Connector Joined]()
i) C\_r = 2.5 when the centroid of connectors or connector group in the end block is within S/20 from the column end.
ii) C\_r = 3.0 when the centroid of connectors or connector group in the end block is between S/20 and S/10 from the column end.
**d)** For individual members of spaced columns, S/d ratio shall not exceed 80.
### 11.7.5 Structural Members Subjected to Bending and Axial Stress
#### 11.7.5.1
Structural members subjected to both bending and axial compression shall be designed to comply with the following formula:
$$
\frac{f_{cc}}{f_{pc}} + \frac{f_b}{f_{pb}} \leq 1
$$
(11.7.10)
#### 11.7.5.2
Structural members subject to both bending and axial tension shall be designed to comply with the following formula
$$
\frac{f_{ct}}{f_{pt}} + \frac{f_b}{f_{pb}} \leq 1
$$
(11.7.11)
## 11.8 Joints
### 11.8.1 Common Steel Wire Nail Joints
#### 11.8.1.1 Design Consideration
**a)** Where a number of nails are used in a joint, the allowable load in lateral resistance shall be the sum of the allowable load for the individual nails, provided that the centroid of the group of these nails lie on the axis of the member and the spacing conforms to Sec 11.8.1.5. Where a large number of nails are to be provided at a joint, they shall be arranged that there are more rows than the number of nails in a row.
**b)** Nails shall as far as practicable, be arranged so that the line of force in a member passes through the centroid of the group of nails. Where this is not practicable, allowance shall be made for any eccentricity in computing the maximum load on the fixing nails as well as the loads and bending moment in the member.
**c)** Adjacent nails shall preferably be driven from opposite faces, that is, the nails are driven alternately from either face.
**d)** For a rigid joint, a minimum of 2 nails for nodal joints and 4 nails for lengthening joint shall be driven.
**e)** Two nails in a horizontal row are better than using the same number of nails in a vertical row.
#### 11.8.1.2 Dimension of Members
**a)** The minimum thickness of the main members in mono-chord construction shall be 30 mm.
**b)** The minimum thickness of an individual piece of member in split chord construction shall be 20 mm for web members and 25 mm for chord members.
**c)** The space between two adjacent pieces of timber shall be restricted to a maximum of 3 times the thickness of the individual piece of chord member. In case of web members, it may be greater for joining facilities.
#### 11.8.1.3 Joint Location
No lengthening joint shall preferably be located at a panel point. Generally not more than two, but preferably one, lengthening joint shall be permitted between two panel points of the members.
#### 11.8.1.4 Specification and Diameter of Nails
**a)** The diameter of nails shall be within the limit of one-eleventh to one-sixth of least thickness of members being connected.
**b)** The nails shall be galvanized when exposed to saline conditions.
#### 11.8.1.5 Arrangement of Nails
The end distances, edge distances and spacing of nail shall not be less than those given in (a) and (b) below so as to avoid undue splitting of timber.
**a) Lengthening Joints:** The requirement of spacing of nails in a lengthening joint shall be as shown in Table 6.11.14 (see Fig 6.11.5).
**Table 6.11.14: Spacing of Nails in a Lengthening Joint**
![Fig. 6.11.5 Spacing of Nails in a Lengthening Joint (a) Monochord Type Butt Joint Subjected to Compression (b) Monochord Type Butt Joint Subjected to Tension]()
![Fig. 6.11.5 Spacing of Nails in a Lengthening Joint (c) Split-Chord Type Butt Joint Subjected to Compression (d) Split-Chord Type Butt Joint Subjected to Tension]()
| Spacing of Nails | Type of Stress in the Joint | Requirement (Minimum) |
| ------------------------------------------------ | --------------------------- | --------------------- |
| End distance | Tension | 12φ |
| | Compression | 10φ |
| In direction of grain | Tension | 10φ |
| | Compression | 5φ |
| Edge distance | - | 5φ |
| Between rows of nails perpendicular to the grain | - | 5φ |
Note: The 5φ distance between rows perpendicular to grain may be increased subject to the availability of width of the member keeping edge distance constant.
**b) Node Joints:** The requirement of spacing of nails in node joints shall be as specified in Fig 6.11.6 where the members are at right angles and as in Fig 6.11.7 where the members are inclined to one another at angles other than 90° and subject to either pure compression or pure tension.
![Fig. 6.11.6 Spacing of Nails Where Members are at Right Angles to One Another]()
![Fig. 6.11.7 Spacing of Nails of Node Joints Where Members are Inclined to One Another]()
#### 11.8.1.6 Penetration of Nails
**a)** For a lap joint when the nails are driven from the side of the thinner member, the length of penetration of nails in the thicker member shall be one and a half times the thickness of the thinner member subject to a maximum of the thickness of the thicker member.
**b)** For butt joints the nails shall be driven through the entire thickness of the joint.
#### 11.8.1.7 Nail Jointed Truss Construction
**a)** The slant braced member provided at the centre of the lower chord of nail jointed timber trusses shall not be less than 1/200 for timber structures using seasoned wood and 1/100 for unseasoncd or partially seasoned wood.
**b)** The total combined thickness of the gusset or splice plates on either side of the joint in a mono-chord type construction shall not be less than one and a half times the thickness of the main members subject to a minimum thickness of 25 mm of individual gusset plate.
**Note 1:** The allowable load or lateral strength values of nails shall be as given in Table 6.11.1
**Note 2:** The strength data for joints given in this section apply to gusset or splice or fish plates of solid wood. However, materials other than solid wood may be used for gusset when field tests are made and their strength requirements have been established.
### 11.8.2 Bolted Joints
#### 11.8.2.1 Design Consideration
**a)** Beams shall be designed in accordance with Sec 11. 6.
**b)** Where a number of bolts are used in a joint, the allowable load in withdrawal or lateral resistance shall be the sum of the allowable loads for the individual bolts.
#### 11.8.2.2 Arrangement of Bolts
**a)** The following spacing of bolts shall be followed in bolted joints (see Fig 6.11.8).
![Fig. 6.11.8 Typical Spacing of Bolts in Structural Joints]()
i) **Spacing of Bolts in a Row:** For parallel and perpendicular to grain loading the spacing shall be 4φ
ii) **Spacing between Rows of Bolts:**
1. For perpendicular to grain loading: 2.5φ to 5φ (2.5φ for t/φ ratio of 2 and 5φ for t/φ ratio of 6)
**Note:** t is the thickness of main member
2. For parallel to grain loading: At least (N-4)φ with a minimum of 2.5φ, where N is the total number of bolts. Also governed by net area at critical section which shall be 80 per cent of the total area in bearing under all bolts.
iii) **End Distance:** 7φ for soft woods in tension, 5φ for hardwoods in tension and 4φ for all species in compression.
iv) **Edge Distance:**
1. For parallel to grain loading: 1.5φ or half the distance between rows of bolts, whichever is greater.
2. For perpendicular to grain loading, the loaded edge distance shall be at least 4φ.
**b)** For inclined members, the spacing given above for perpendicular and parallel to grain of wood may be used as a guide and bolts arranged at the joint with respect to loading direction.
**c)** The bolts shall be arranged in such a manner as to pass the centre of resistance of bolts through the intersection of the gravity axis of the members.
**d)** Staggering of bolts shall be avoided as far as possible in case of members loaded parallel to grain. For loads acting perpendicular to grain staggering is preferable to avoid splitting due to weather effects.
**e)** The bolt holes shall be bored or drilled perpendicular to the surface involved. Forcible driving of the bolts shall be prohibited to avoid cracking or splitting of members. A bolt hole of 1 mm oversize may be used as a guide for preboring.
## Related Appendix
| Appendix | Title |
| ---------- | ---------------------------------------------- |
| Appendix A | Conversion of Expressions from SI to FPS Units |
# Chapter 12: Ferrocement Structures
Source: https://docs.sayed.app/bnbc2006/part-6-structural-design/chapter-12-ferrocement-structures
## 12.1 Scope
This chapter covers selection, standards and testing of ferrocement materials, design criteria and approaches, construction methods, and maintenance and repair procedures of ferrocement structures. The provisions of this chapter are consistent with those of Chapter 6, except for the special requirements of ferrocement, such as reinforcement cover and limits on deflection.
## 12.2 Terminology
### 12.2.1 Reinforcement Parameters
For the purpose of this chapter, the following parameters characterizing the reinforcement in ferrocement shall have the definitions given:
**VOLUME FRACTION OF REINFORCEMENT ($V_f$)**: Volume fraction of reinforcement is the total volume of reinforcement divided by the volume of composite (reinforcement and matrix). For a composite reinforced with meshes with square openings, $V_f$ shall be equally divided into $V_l$ and $V_t$ for the longitudinal and transverse directions, respectively. For other types of reinforcement, such as expanded metal, $V_l$ and $V_t$ may be unequal. Procedures for computation of $V_f$ are shown in Appendix D.
**SPECIFIC SURFACE OF REINFORCEMENT ($S_r$)**: $S_r$ is the total bonded area of reinforcement (interface area or area of the steel that comes in contact with the mortar) divided by the volume of the composite.
For a ferrocement plate of width $b$ and depth $h$, the specific surface of reinforcement can be computed from
$$
S_r = \frac{\Sigma o}{bh}
$$
(12.2.1)
in which $\Sigma o$ is the total surface area of bonded reinforcement per unit length.
### 12.2.2 Notation
| Symbol | Definition |
| ----------------------------- | --------------------------------------------------------------------------------------------------------------------------------------- |
| $A_c$ | cross-sectional area of ferrocement composite |
| $A_e$ | total effective cross-sectional area of reinforcement in the direction considered |
| $A_e = \sum_{i=1}^{N} A_{ei}$ | (sum notation) |
| $A_{ei}$ | effective cross-sectional area of reinforcement of mesh layer $i$ in the direction considered |
| $b$ | width of ferrocement section |
| $d$ | distance from extreme compression fibre to neutral axis |
| $C_c$ | resultant of the compressive stress block in ferrocement |
| $C_i$ | compressive force in ferrocement layer $i$ |
| $d_c$ | clear cover of mortar over first layer of mesh |
| $d_b$ | diameter or equivalent diameter of reinforcement used |
| $d_i$ | distance from extreme compression fibre to centroid of reinforcing layer $i$ |
| $E_c$ | elastic modulus of mortar matrix |
| $E_r$ | effective modulus of the reinforcing system |
| $f_c'$ | specified compressive strength of ferrocement mortar |
| $f_y$ | yield strength of mesh reinforcement or reinforcing bars |
| $h$ | thickness of ferrocement section |
| $M_n$ | nominal moment strength |
| $N_n$ | nominal tensile strength |
| $N$ | number of layers of mesh; nominal resistance |
| $n_r$ | modular ratio of reinforcement |
| $o$ | mesh opening or size |
| $S_r$ | specific surface of reinforcement |
| $S_l$ | specific surface of reinforcement in the longitudinal direction |
| $S_t$ | specific surface of reinforcement in the transverse direction |
| $T_i$ | tensile force in the ferrocement layer $i$ |
| $V_f$ | volume fraction of reinforcement |
| $U$ | minimum required design strength |
| $V_{fi}$ | volume fraction of reinforcement for mesh layer $i$ |
| $V_l$ | volume fraction of reinforcement in the longitudinal direction |
| $V_t$ | volume fraction of reinforcement in the transverse direction |
| $\beta_1$ | factor defining depth of rectangular stress block |
| $\eta$ | global efficiency factor of embedded reinforcement in resisting tension or tensile bending loads |
| $\eta_l$ | value of $\eta$ when the load or stress is applied along the longitudinal direction of the mesh system or rod reinforcement |
| $\eta_t$ | value of $\eta$ when the load or stress is applied along the transverse direction of the mesh reinforcement system or rod reinforcement |
| $\eta_\theta$ | value of $\eta$ when the load or stress is applied along a direction forming an angle with the longitudinal direction |
| $\varepsilon_{ei}$ | strain of mesh reinforcement at layer $i$ |
| $\varepsilon_y$ | nominal yield strain of mesh reinforcement $= \frac{f_y}{E_r}$ |
| $\Sigma o$ | total surface area of bonded reinforcement per unit length |
| $\phi$ | strength reduction factor |
The relation between $S_r$ and $V_f$ when square grid wire meshes are used is
$$
S_r = \frac{4V_f}{d_b}
$$
(12.2.2)
where $d_b$ is the diameter of the wire. For other types of reinforcement, such as expanded metal, $S_l$ and $S_t$ may be unequal.
**EFFECTIVE MODULUS OF THE REINFORCEMENT**: For welded steel meshes, effective modulus of the reinforcing system, $E_r$ shall be taken equal to the elastic modulus of the steel wires. For other meshes, $E_r$ shall be determined from tensile tests on the ferrocement composite as specified in Sec 12.8.
### 12.2.3 Definitions
**ARMATURE**: The total reinforcement system or skeletal reinforcement and mesh for a ferrocement element.
**LONGITUDINAL DIRECTION**: The roll direction (longer direction) of the mesh as produced in plant (see Fig. 6.12.1).
**SKELETAL REINFORCEMENT**: A planar framework or widely spaced tied steel bars that provides shape and support for layers of mesh or fabric attached to either side.
**SPRITZING**: Spraying or squirting a mortar onto a surface.
**TRANSVERSE DIRECTION**: Direction of mesh normal to its longitudinal direction; also width direction of mesh as produced in plant (see Fig. 6.12.1)
![]()
Fig. 6.12.1 Assumed Longitudinal and Transverse Directions of Reinforcement
## 12.3 Materials
The material used in ferrocement consists primarily of mortar made with Portland cement, water and aggregate and the reinforcing mesh.
### 12.3.1 Cement
The cement shall comply with ASTM C150-85a, ASTM C595-85, or an equivalent standard. The cement shall be fresh, of uniform consistency, and free of lumps and foreign matter. It shall be stored under dry conditions for as short a duration as possible.
The choice of a particular cement shall depend on the service conditions. Service conditions can be classified as electrochemically passive or active. Land based structures such as ferrocement silos, bins, and water tanks can be considered as passive structures, except when in contact with sulphate bearing soils, in which case the use of sulphate resistant cement, such as ASTM Type II or Type V, may be necessary.
Blended hydraulic cement conforming to ASTM C595-85 Type I (PM), IS, I (SM), IS-A, IP, or IP-A can also be used.
Mineral admixtures, such as fly ash, silica fumes, or blast furnace slag, may be used to maintain a high volume fraction of fine material. When used, mineral admixtures shall comply with ASTM C618-85 and C989-85a. In addition to the possible improvement of flow ability, these materials also benefit long term strength gain, lower mortar permeability, and in some cases improved resistance to sulphates and chlorides.
### 12.3.2 Aggregates
Aggregate used in ferrocement shall be normal weight fine aggregate (sand). It shall comply with ASTM C33-86 requirements (for fine aggregate) or an equivalent standard. It shall be clean, inert, free of organic matter and deleterious substances, and relatively free of silt and clay.
The grading of fine aggregate shall be in accordance with the guidelines of Table 6.12.1. However, the maximum particle size shall not be controlled by construction constraints such as mesh size and distance between layers. A maximum particle size passing sieve No. 16 (1.18 mm) may be considered appropriate in most applications. The sand shall be uniformly graded unless trial testing of mortar workability permits the use of a gap graded sand.
Aggregates that react with the alkalis in cement shall be avoided. When aggregates may be reactive, they shall be tested in accordance with ASTM C227-81. If proven reactive, the use of a pozzolan to suppress the reactivity shall be considered and evaluated in accordance with ASTM C441-81.
| Sieve Size U.S. Standard Square Mesh | Per cent Passing by Weight |
| ------------------------------------ | -------------------------- |
| No. 8 (2.36 mm) | 80 - 100 |
| No. 16 (1.18 mm) | 50 - 85 |
| No. 30 (0.60 mm) | 25 - 60 |
| No. 50 (0.30 mm) | 10 - 30 |
| No. 100 (0.15 mm) | 2 - 10 |
Table 6.12.1 Guidelines for Grading of Sand
### 12.3.3 Water
The mixing water shall be fresh, clean, and potable. The water shall be relatively free from organic matter, silt, oil, sugar, chloride, and acidic material. It shall have a pH ≥ 7 to minimize the reduction in pH of the mortar slurry. Salt water is not acceptable, but chlorinated drinking water can be used.
### 12.3.4 Admixtures
Conventional and high range water reducing admixtures (superplasticizers) shall conform to ASTM C494-86. Water reducing admixtures may be used to achieve an increase in sand content for the same design strength or a decrease in water content for the same workability. Decreases in water content result in lower shrinkage and less surface crazing. Retarders may be used in large time consuming plastering projects, especially in hot weather conditions.
If watertightness is important, such as in water or liquid retaining structures, special precautions shall be taken. To achieve watertightness, the water cement ratio shall preferably be kept below 0.4, and if necessary, waterproofing coatings applied (see Sec 12.6.3) and, if necessary, waterproofing coatings applied (see Sec 12.6.3) and, if necessary, waterproofing coatings applied (see Sec 12.6.3).
Mineral admixtures such as fly ash (ASTM C618-85) can be added to the cement to improve sand content for the same design strength or a decrease in water content for the same workability. Decreases in water content result in lower shrinkage and less surface crazing. Pozzolanic admixtures may be added to replace part of the fine aggregates to improve plasticity. The tendency for some natural pozzolans to absorb water and thus adversely affect hydration of the cement phase shall be checked by measuring the water of absorption.
A quality matrix can be obtained without using any admixtures if experience has shown its applicability. Admixtures not covered in ASTM standards shall not be used.
### 12.3.5 Mix Proportioning
The proportions for common ferrocement applications shall be sand cement ratio by weight, 1.5 to 2.5, and water cement ratio by weight, 0.35 to 0.5. The higher the sand content, the higher the required water content to maintain the same workability. Fineness modulus of the sand, water cement ratio, and sand cement ratio shall be determined from trial batches to ensure a mix that can infiltrate (encapsulate) the mesh and develop a strong and dense matrix.
The moisture content of the aggregate shall be considered in the calculation of required water. Quantities of materials shall preferably be determined by weight.
The mix shall be as stiff as possible, provided it does not prevent full penetration of the mesh. Normally the slump of fresh mortar shall not exceed 50 mm. For most applications, the 28 day compressive strength of 75 by 150 mm moist cured cylinders shall not be less than 35 N/mm².
### 12.3.6 Reinforcement
The reinforcement shall be clean and free from deleterious materials such as dust, loose rust, coating of paint, oil, or similar substances.
Wire mesh with closely spaced wires is the most commonly used reinforcement in ferrocement. Expanded metal, welded wire fabric, wires or rods, prestressing tendons, and discontinuous fibres may also be used in special applications or for reasons of performance or economy.
#### 12.3.6.1 Wire Mesh
Reinforcing meshes for use in ferrocement shall be evaluated for their susceptibility to take and hold shape as well as for their strength performance in the composite system. Common types and sizes of steel meshes that may be used in ferrocement are provided in Appendix E.
#### 12.3.6.2 Welded Wire Fabric
Welded wire fabric may be used in combination with wire mesh to minimize the use of reinforcement. The fabric shall conform to ASTM A496-85 and A497-85. The minimum yield strength of the measured at a strain of 0.035 shall be 410 N/mm². Welded wire fabric normally contains larger diameter wires (2 mm or more) spaced at 25 mm or more.
#### 12.3.6.3 Expanded Metal Mesh Reinforcement
Expanded mesh reinforcement (metal lath), formed by slitting thin gauge steel sheets and expanding them in a direction perpendicular to the slits, may be used in ferrocement. Punched or otherwise perforated sheet products may also be used. Expanded mesh is suitable for tanks if proper construction procedures are adopted.
#### 12.3.6.4 Bars, Wires and Prestressing Strands
Reinforcing bars and prestressing wires or strands may be used in combination with wire meshes in relatively thick ferrocement elements or in the ribs of ribbed or T-shaped elements.
Reinforcing bars shall conform to ASTM A615-86, A616-86 or A617-84. Reinforcing bars shall be steel with a minimum yield strength of 280 N/mm and a tensile strength of about 615 N/mm². Prestressing wires and strands, whether prestressed or not shall conform to ASTM A421-80 and A416-86, respectively.
#### 12.3.6.5 Discontinuous Fibres and Nonmetallic Reinforcement
Fibre reinforcement consisting of irregularly arranged continuous filaments of synthetic or natural organic fibres such as jute and bamboo may be used in ferrocement. If organic materials are used, care shall be taken to conduct appropriate investigations to ensure the strength and durability of the finished ferrocement product.
## 12.4 Design
### 12.4.1 General Principles and Requirements
#### 12.4.1.1
The analysis of a ferrocement cross-section subject to either bending, or to bending and axial load, whether based on strength or working stresses, is similar to the analysis of a reinforced concrete beam or column having several layers of steel (Fig. 6.12.2).
#### 12.4.1.2
In the design of ferrocement structures, members shall be proportioned for adequate strength in accordance with the provisions of this chapter using load factors and strength reduction factors specified in Chapter 6.
#### 12.4.1.3
Ferrocement members may alternatively be designed using service loads and permissible service load stresses in accordance with the provisions of Sec 12.4.3.
#### 12.4.1.4
All members shall also be designed to satisfy serviceability criteria in accordance with the provisions of Sec 12.4.4.
![]()
Fig. 6.12.2 Strain and Force Distribution at Ultimate in a Ferrocement Section Under Bending
### 12.4.2 Strength Requirements
Ferrocement structures and structural members shall have a design strength at all sections at least equal to the required strengths for the factored load and load combinations stipulated in Chapter 1, General Design
Requirements. Required strength $U$ to resist dead load $D$ and live load $L$ shall be determined in accordance with Chapter 2, Sec 2.7.5.1.
Design strength provided by a member or cross-section in terms of axial load, bending moment, shear force, or stress shall be taken as the nominal strength calculated in accordance with requirements and assumptions of Chapter 6, Sec 6.1.4 multiplied by the strength reduction factor $\phi$ to satisfy the general relationship.
$$
U \leq \phi N
$$
(12.4.1)
where $U$ is the factored load (equal to the minimum required design strength), $N$ is the nominal resistance, and $\phi$ is a strength reduction factor defined in Sec 6.1.4.2.
Design strength for the mesh reinforcement shall be based on the yield strength $f_y$ of the reinforcement but shall not exceed 690 N/mm². Design yield strengths of various mesh reinforcement shall be in accordance with Table 6.12.2. These shall be used for design only when test data are not available. When tests for determination of yield strength are needed, they shall be conducted in accordance with Sec 12.8.2.3 and 12.8.2.4.
| | | Woven Square Mesh | Welded Square Mesh | Hexagonal Mesh | Expanded Metal Mesh | Longitudinal Bars |
| ----------------- | ------------------- | ----------------- | ------------------ | -------------- | ------------------- | ----------------- |
| Yield Strength | $f_y$ N/mm² | 450 | 450 | 310 | 310 | 410 |
| | $(V_f \eta)_{long}$ | | | | | |
| Effective Modulus | $(N/mm²)$ | 138000 | 200000 | 104000 | 138000 | 200000 |
| | $(N/mm²)$ | 165000 | 200000 | 69000 | 69000 | - |
Table 6.12.2 Minimum Values of Yield Strength and Effective Modulus for Steel Meshes and Bars Recommended for Design
#### 12.4.2.1 Flexure
The strain distribution at nominal moment resistance shall be assumed to be linear, and a rectangular stress block shall be used in computing the resultant compressive force acting on the concrete.
a) Assumptions - Strength design of ferrocement members for flexure and axial loads shall be based on the following assumptions and on satisfaction of equilibrium and compatibility of strains.
i) Strain in reinforcement and mortar (concrete) shall be assumed directly proportional to the distance from the neutral axis.
ii) Maximum strain at extreme mortar (concrete) compression fibre shall be assumed equal to 0.003.
iii) Stress in reinforcement below specified yield strength $f_y$ shall be taken as $E_r$ times steel strain. For strains greater than that corresponding to $f_y$, stress in reinforcement shall be considered independent of strain and equal to $f_y$.
iv) Tensile strength of mortar (concrete) shall be neglected in flexural strength calculations.
v) Relationship between mortar (concrete) compressive stress distribution and mortar (concrete) strain may be considered satisfied by the use of the equivalent rectangular concrete stress distribution.
b) Effective area of reinforcement - The area of reinforcement per layer of mesh considered effective to resist tensile force in a cracked ferrocement section shall be determined as follows:
$$
A_{si} = \eta V_f A_c
$$
(12.4.2)
where
$A_{si}$ = effective area of reinforcement for mesh layer $i$
$\eta$ = global efficiency factor of mesh reinforcement in the loading direction considered
$V_f$ = volume fraction of reinforcement for mesh layer $i$
$A_c$ = gross cross-sectional area of mortar (concrete) section.
The global efficiency factor $\eta$ when multiplied by the volume fraction of reinforcement, gives the equivalent volume fraction (or equivalent reinforcement ratio) in the loading direction considered. In effect, it leads to an equivalent volume fraction for (equivalent reinforcement ratio) in the loading direction considered. For square meshes, $\eta = 0.5$ when loading is applied in one of the principal directions. For a reinforcing bar loaded along its length, $\eta = 1.0$.
In the absence of values derived from tests for a particular mesh system, the values of $\eta$ given in Table 6.12.3 for common types of mesh and loading direction may be used. The global efficiency factor shall apply whether the reinforcement is in the tension zone or in the compression zone.
The value of $\eta = 0.2$ for expanded metal mesh (Table 6.12.3) may not always be conservative, particularly in thicker sections in flexure with the mesh oriented in the short way direction. The values in Table 6.12.3 shall be used for sections 50 mm or less in thickness, and tests conducted for global efficiency values for sections more than 50 mm in thickness.
| | | Woven Square Mesh | Welded Square Mesh | Hexagonal Mesh | Expanded Metal Mesh | Longitudinal Bars |
| ------------------------ | ---------------------- | ----------------- | ------------------ | -------------- | ------------------- | ----------------- |
| Global efficiency factor | Longitudinal, $\eta_l$ | 0.50 | 0.50 | 0.45 | 0.65 | 1 |
| | Transverse, $\eta_t$ | 0.50 | 0.50 | 0.30 | 0.20 | 0 |
| | At 45°, $\eta_{45}$ | 0.35 | 0.35 | 0.30 | 0.30 | 0.70 |
Table 6.12.3 Recommended Design Values of the Global Efficiency Factor $\eta$ of Reinforcement for a Member in Uniaxial Tension or Bending
#### 12.4.2.2 Tension
The nominal resistance of cracked ferrocement elements subject to pure tensile loading shall be approximated by the load carrying capacity of the mesh reinforcement alone in the direction of loading by the following equation:
$$
N_n = A_s f_y
$$
(12.4.3)
where
$N_n$ = nominal tensile load resistance in direction considered
$A_s$ = effective cross-sectional area of reinforcement in direction considered
$f_y$ = yield stress of mesh reinforcement
The value of $A_s$ is given by
$$
A_s = \sum_{i=1}^{N} A_{ei}
$$
(12.4.4)
where
$N$ = number of mesh layers
$A_{ei}$ = effective area of reinforcement for mesh layer $i$ (Eq 12.4.2)
#### 12.4.2.3 Compression
As a first approximation, the nominal resistance of ferrocement sections subject to uniaxial compression shall be derived from the load carrying capacity of the unreinforced mortar (concrete) matrix assuming a uniform stress distribution of 0.85$f_c'$ where $f_c'$ is the design compressive strength of the mortar and matrix. However, the transverse component of the reinforcement can contribute additional strength when square or rectangular wire meshes are used. Expanded mesh contributes virtually no strengthening beyond that achieved by the mortar alone. Slenderness effects of thin sections, which can reduce the load carrying capacity below that based on the design compressive strength shall be considered.
### 12.4.3 Service Load Design
#### 12.4.3.1 Flexure
For investigation of stresses at service loads, straight line theory (for flexure) shall be used with the following assumptions.
a) Strains vary linearly with distance from the neutral axis.
b) Stress strain relationships of mortar (concrete) and reinforcement are linear for stresses less than or equal to permissible service load stresses.
#### 12.4.3.2 Allowable Tensile Stress
The allowable tensile stress in the mesh reinforcement under service load conditions shall be taken as 0.60$f_y$ where $f_y$ is the yield strength. For liquid retaining and sanitary structures, the allowable tensile stress shall be limited to 200 N/mm². Consideration shall be given to increase the allowable tensile stresses if crack width measurements on a model test indicate that a higher stress will not impair performance.
#### 12.4.3.3 Allowable Compressive Stress
The allowable compressive stress in either the mortar (concrete) or the ferrocement composite shall be taken as 0.45$f_c'$ where $f_c'$ is the specified compressive strength of the mortar. Measurements of the mortar compressive strength shall be obtained from tests on 75 mm x 150 mm cylinders.
### 12.4.4 Serviceability Requirements
Ferrocement structures shall generally satisfy the intent of the serviceability requirements of Chapter 6 except for the concrete cover.
#### 12.4.4.1 Crack Width Limitations
The maximum value of crack width under service load conditions shall be less than 0.10 mm for noncorrosive environments and 0.05 mm for corrosive environments and/or water retaining structures.
#### 12.4.4.2 Fatigue Stress Range
For ferrocement structures to sustain a minimum fatigue life of two million cycles, the stress range in the reinforcement shall be limited to 200 N/mm². A stress range of 350 N/mm² shall be used for one million cycles. Higher values may be considered if justified by tests.
#### 12.4.4.3 Corrosion Durability
Particular care shall be taken to ensure a durable mortar matrix and optimize the parameters that reduce the risk of corrosion.
#### 12.4.4.4 Deflection Limitation
Since ferrocement in thin sections is very flexible and its design is very likely to be controlled by criteria other than deflection, no particular deflection limitation is recommended.
### 12.4.5 Particular Design Parameters
#### 12.4.5.1
The cover of the reinforcement shall be about twice the diameter of the mesh wire or thickness of other reinforcement used. A smaller cover is acceptable provided the reinforcement is not susceptible to rapid corrosion, the surface is protected by an appropriate coating, and the crack width is limited to 0.05 mm. For ferrocement elements of thickness less than 25 mm, a cover of the order of 2 mm shall be provided.
#### 12.4.5.2
For a given ferrocement cross-section of total thickness $h$, the mesh opening shall not be larger than $h$.
#### 12.4.5.3
For nonprestressed water retaining structures the total volume fraction of reinforcement shall not be less than 3.5 per cent and the total specific surface of reinforcement shall not be less than 0.16 mm²/mm³.
#### 12.4.5.4
In computing the specific surface of the reinforcement, the contribution of fibres added to the matrix shall be considered, while the fibre contribution may be ignored in computing the volume fraction of reinforcement.
#### 12.4.5.5
If skeletal reinforcement is used, the skeletal reinforcement shall not occupy more than 50 per cent of the thickness of the ferrocement composite.
#### 12.4.5.6
For a given volume fraction of reinforcement, better performance in terms of crack widths, water tightness, and ductility may be achieved by uniform distribution of the reinforcement throughout the thickness and by increasing its specific surface. A minimum of two layers of mesh shall be acceptable, but more than two layers of reinforcement are preferable.
### 12.4.6 Design Aids
The following nondimensional equation can be used to predict the nominal moment strength of ferrocement beams subjected to pure bending:
$$
\frac{M_n}{f_c' b h^2 \eta} = 0.005 + 0.422\left(\frac{V_f f_y}{f_c'}\right) - 0.0772\left(\frac{V_f f_y}{f_c'}\right)^2
$$
(12.4.5)
A design graph representing Eq (12.4.5) is given in Fig 6.12.3.
![]()
Fig. 6.12.3 Chart for Strength Design of Ferrocement in Bending
## 12.5 Fabrication
### 12.5.1 General Requirements
This section specifies the requirements for the mixing, placing, and handling of materials used in ferrocement construction.
#### 12.5.1.1 Planning
Plastering for fabrication with ferrocement shall be continuous through the completion of the job. This requires a large number of workers involved in plastering and in maintaining a constant supply of materials during work, most often in confined work spaces. Adequate bond at cold joints may be achieved through surface roughness or treatment with bonding agents. Retarders may be useful in large time consuming plastering projects, especially in hot weather conditions. Planning for the job shall take into account all these requirements.
#### 12.5.1.2 Mixing
Any method, including hand mixing, which assures a homogeneous mixture of ingredients shall be satisfactory. Mixing may be accomplished in a mortar mixer with a spiral blade or paddles inside a stationary drum or in a pan type mixer. The use of rotating drum mixers with fins affixed to the sides shall not be permitted. Mix ingredients shall be carefully batched by weight, including the water, and added in the proper sequence so that there is no caking. Mix water shall be accurately weighed so that the water cement ratio is controlled. The water cement ratio shall be as low as possible but the sand cement ratio shall be adjusted to provide a fluid mix for initial penetration of the armature followed by a stiffer more heavily sanded mix at the finish. Mortar shall be mixed in batches so that mortar is plastered within an hour after mixing. Retempeering of the mortar shall be prohibited.
#### 12.5.1.3 Mortar Placement
Mortar shall generally be placed by hand plastering. In this process, the mortar is forced through the mesh. Alternatively, the mortar may be shot through a spray gun device.
#### 12.5.1.4 Finishing
Surfaces shall be finished to assure proper cover to the last mesh layer. The surface finish shall be slightly roughened if a surface coating is to be bonded later.
Surfaces that are too smooth shall be mechanically abraded by sandblasting or other means of mechanical abrasion. Alternatively, such surfaces may be etched with phosphoric acid, provided the etched left by it will not interfere with specified finishes. Mild solutions of muriatic acid may be applied with proper attention to corrosion potential. Additional care shall be taken when plastering around openings.
#### 12.5.1.5 Curing
Moist or wet curing is essential for ferrocement concrete construction. The low water cement ratio and high cement factors create a demand for large quantities of free water in the hydration process, and the amount permitted to evaporate into the air shall be kept to an absolute minimum. The use of fogging devices under a moisture retaining enclosure is desirable. A double layer of soaked burlap covered with polyethylene or a soaker hose may also be used. Continuous wetting of the surface or of wet curing shall be maintained to avoid dry spots. Curing shall start within a reasonable time after application of the finishing layer.
### 12.5.2 Construction Methods
All methods shall have high level quality control criteria to achieve the complete encapsulation of several layers of reinforcing mesh by a well compacted mortar or concrete matrix with a minimum of trapped air. The most appropriate fabrication technique shall be decided on the basis of the nature of the particular ferrocement application, the availability of mixing, handling, and placing machinery, and the skill and cost of available labour. Several recommended construction methods are outlined in the following subsections.
#### 12.5.2.1 Armature System
The armature system is a framework of tied reinforcing bars (skeletal steel) to which layers of reinforcing mesh are attached on each side. Mortar is then applied from one side and forced through the mesh layers towards the other side, as shown in Fig 6.12.4.
![]()
Fig. 6.12.4 Armature System
The skeletal steel can assume any shape. Diameter of the steel bars depends on the size of the structure. Skeletal steel shall be of a specified lengths, bent to the proper profile, and tied in proper sequence. Sufficient embedment lengths shall be provided to ensure continuity. For bar sizes 6 mm or less, lap lengths from 230 to 300 mm may be sufficient. The required number of layers of mesh shall be tied to each side of the skeletal steel frame.
#### 12.5.2.2 Closed-mould System
The mortar is applied from one side through several layers of mesh or mesh and rod combinations that have been stapled or otherwise held in position against the surface of a closed mould, i.e. a male mould or a female mould. The mould may remain as a permanent part of the finished ferrocement structure. If removed, treatment with release agents may be needed. The use of the closed mould system represented in Fig 6.12.5 tends to eliminate the use of rods or bars, thus permitting an essentially all mesh reinforcement. It requires that plastering be done from one side only.
![]()
Fig. 6.12.5 Closed-mould System
#### 12.5.2.3 Integral-mould System
An integral mould is first constructed by application of mortar from one or two sides onto a semi-rigid framework (such as a rigid but low quality ferrocement mould on which further layer of reinforcing mesh and mortar shall be applied on both sides. Alternatively, the integral mould may be formed using rigid insulation materials, such as polystyrene or polyurethane, as the core. A schematic description of this system is given in Fig 6.12.6.
![]()
Fig. 6.12.6 Integral-mould System
#### 12.5.2.4 Open-mould System
In the open-mould system, mortar is applied from one side through layers of mesh or mesh and rods attached to an open mould made of a lattice of wood strips. The form, shown in Fig 6.12.7, is coated with a release agent or entirely covered with polyethylene sheeting (thereby forming a closed but nonrigid and transparent mould) to facilitate mould removal and to permit observation and/or repair during the mortar application process.
![]()
Fig. 6.12.7 Open-mould System
This system is similar to the closed-mould system in which the mortar is applied from one side, at least until the mould can be removed. It enables at least part of the underside of the mould to be viewed and repaired, where necessary, to ensure complete and thorough impregnation of the mesh.
## 12.6 Maintenance
### 12.6.1 General
Terrestrial structures are susceptible to deterioration from pollutants in ground water and those that precipitate from the air (acid rain). Environmental temperature and humidity variations also affect ferrocement durability and maintenance procedures.
Maintenance shall involve detecting and filling voids, replacing spalled cover, providing protective coatings, and cosmetic treatment of surface blemishes. Due to the thin cover in ferrocement, muriatic acid (hydrochloric acid) shall be used with extreme caution. Phosphoric acid and other nonchloride cleaners shall be specified alternative (see Sec 12.5.1.4).
Repairs not involving large quantities of materials shall be accomplished by hand. Emphasis shall be placed on the ability of the repair material to penetrate the mesh cage, to fully coat the reinforcing to inhibit corrosion, and to bond to the substrate. Rapid set and strength gain shall be the overriding considerations for emergency repairs. Protective coatings shall bond well and be alkali tolerant, thermally compatible, and resistant to environmental pollutants and ultraviolet radiation, if exposed.
### 12.6.2 Blemish and Stain Removal
#### 12.6.2.1 General
Since ferrocement is usually less porous than conventional concrete, stains do not penetrate very deep in the mortar matrix. Care shall be taken when preparing the surface not to diminish the thin cover of mortar over ferrocement reinforcement.
#### 12.6.2.2 Construction Blemishes
Construction blemishes are often caused by improper selection or use of materials, faulty workmanship, uneven evaporation, and uneven curing. Care shall be exercised to minimize these and the following causes of blemishes in ferrocement.
a) Cement from different mills will cause colour variation, although most of the colour in mortar is due to the sand component. Where appearance is critical, care shall be taken to obtain sand from a single source and have it thoroughly washed.
b) Mottling results from the use of calcium chloride or high alkali cement combined with uneven curing.
c) The use of polyethylene sheet material to cover surfaces promotes uneven curing.
d) The water cement ratio affects tone and surface appearance. Low water cement ratio will result in a darker appearance.
e) Hard steel trowelling densifies the surface, causing more rapid drying and also leaving a darkened surface.
#### 12.6.2.3 Stain Removal
Treatment of stains shall be done promptly after discoloration appears. Through flushing and brushing with a stiff brush and detergent is the first approach. If this is ineffective, a dilute (about three per cent) solution of phosphoric or acetic acid shall be applied. Another chemical treatment that may be considered safe and effective is a 20 to 30 per cent solution of diammonium citrate, a mild acid that attacks calcium carbonates and calcium hydroxides. This treatment makes the surface more porous and promotes hydration.
When a stain has penetrated too deeply to be removed by surface chemical application and scrubbing, a poultice or a bandage may be needed. A poultice is intended to dissolve the stain and absorb it into the poultice. The poultice is made by mixing one or more chemicals such as a solution of phosphoric acid with a fine inert powder such as talc, whiting, hydrated lime, or diatomaceous earth to form a paste. The paste is spread in a thick layer over the stain and allowed to dry. A bandage may consist of a few layers of cloth or paper towel soaked in a chemical solution. More than one application of a poultice or bandage may be needed for stubborn stains.
Caution:
Most of the chemicals used to remove stains are toxic and require safeguards against skin contact and inhalation. Whenever acids are used, surfaces shall first be saturated with water or the dissolved stain material may migrate deeper into the concrete and reappear at a later date as efflorescence.
#### 12.6.2.4 Efflorescence
Efflorescence is caused by deposition of salts on the surface due to the evaporation of migrating water bearing salts from within ferrocement; it is typically associated with a porous ferrocement. Water cement ratio shall be limited to within 0.4 and the mortar well compacted to minimize efflorescence. Voids, if present, may be treated by breaking into with a hammer and replastering. Alternatively, voids may be drilled into with a masonry bit and repaired by injecting a non shrinking cement grout.
### 12.6.3 Protective Surface Treatments
#### 12.6.3.1 General
Good quality mortar has excellent resistance to weathering. The application of protective surface treatments can improve the performance of ferrocement and extend its useful service life. Surface treatments shall be used to improve appearance, harden the surface, and reduce permeability, thus guarding against the corrosive action of acids, alkaline salts, and organic substances.
#### 12.6.3.2 Hardeners
Hardeners may be used to protect the ferrocement surface or to seal and prepare it for application of paints. When a sodium silicate hardener is used, it shall be diluted with water. The actual proportion of water to be used shall depend on the manufacturer's recommendation. The hardener shall be applied in multiple coats with the first coat being more dilute than the subsequent ones. Each coat must be completely dry before the next coat is applied.
Other hardeners that seal and prepare the surface for application of oil base paints are magnesium fluorosilicate and zinc fluorosilicate. The treatment shall consist of two or more applications. A solution containing about 1 kg of fluorosilicate crystals per 10 litres of water shall be used for the first application; and a solution containing 2.4 kg per 10 litres of water shall be used for subsequent applications. After the last application has dried, the surface shall be brushed and washed with water to remove any crystals that may have formed.
#### 12.6.3.3 Coatings
When resistance to abrasion is desired, ferrocement surfaces may be coated with polyurethanes, especially those furnished in two part mixtures. Coatings formulated from acrylics, may be used to provide resistance to sunlight and weathering. Water based acrylic latex house paints may be used for application to damp surfaces. For any surface opposite a surface sealed with an impermeable coating, an acrylic coating formulated to allow the escape of water vapour shall be specified.
## 12.7 Damage Repair
### 12.7.1 Common Types of Damage
Ferrocement structures shall be inspected, as part of a regular maintenance programme, to detect any of the following types of damage. Appropriate repair measures shall then be taken.
#### 12.7.1.1 Delaminations
Delaminations occur when ferrocement splits between layers in laminated constructions due to springing back or bridging of the mesh during construction. Delamination sometimes occurs at or near the neutral axis under impact or flexure when there are many voids in the interior layers. Such areas give of a hollow sound when tapped with a hammer or stroked with a steel bar.
#### 12.7.1.2 Spalls
A spall is defined as a depression resulting when a fragment is detached from a larger mass by a blow, by the action of weather, by pressure, or by expansion within the mass. Spalls shall be considered large when their size exceeds approximately 20 mm in depth or 150 mm in any dimension, and shall be repaired by replastering.
Spalls are usually caused by corrosion of steel, which causes an expansive pressure within the ferrocement. Chlorides in the concrete greatly increase the potential for corrosion of the steel. Under such conditions, continued use is likely and the repair of local spalled areas may even promote deterioration of the concrete because of the presence of dissimilar materials.
An area of steel corrosion and chloride contaminated concrete may be considerably larger than the area of spalled concrete, and the full area of contaminated rather than the spall itself shall be broken and replastered.
#### 12.7.1.3 Fire Damage
Ferrocement may be more susceptible to fire damage than conventional concrete because of the thin cover.
If the fire were intense enough to release the amount of chemically bound water in the cement, destroy the bond between the cement and the aggregate, or oxidize the reinforcement, the surface would be charred and spalled so that the damage could be easily identified. Full scale removal and repair shall then be required.
#### 12.7.1.4 Cracks and Local Fractures
Hairline cracks and crazing due to temperature changes or drying shrinkage in the cover coat do not require repair. Continuous wet curing will cause autogenous healing, and a flexible coating will conceal the crack from view. If cracks are caused by continuing overloads or are due to structural settlement and the cause cannot be removed, replacement or a structural overlay shall be required. Cracks due to occasional impact or overload may be repaired. Local fractures are cracks in which displacement of the section has occurred as a result of impact.
### 12.7.2 Evaluation of Damage
#### 12.7.2.1 Evaluation of damage
Evaluation of damage shall take into consideration its extent, cause, and likelihood of the cause still being active. The method of repair shall be dictated by the type of damage, the availability of special equipment and repair materials, and the level of skill of the workers employed. Economic factors may influence the decision as to whether repair shall be extensive and permanent, or limited in scope in response to an immediate problem.
#### 12.7.2.2 Repair materials
Repair materials shall bond to the original structure, resist pollutants in the surrounding soil, water or air, and respond the same way to changes in temperature, moisture, and loads. Removal of deteriorated or chloride contaminated mortar trapped within the reinforcing mesh requires a large amount of hand labour, so it may be economical to reconstruct and replace an entire area using the original structure as a form that can be left in place or removed after the overlaid structure has cured. Rapid set and strength gain shall be the overriding considerations for emergency repairs. Protective coatings shall bond well and be alkali tolerant, thermally compatible, and resistant to environmental pollutants and ultraviolet radiation, if exposed.
#### 12.7.2.3 Testing for damage in ferrocement
Testing for damage in ferrocement may be done by tapping with a hammer to break into and listen for sounds indicating voids or the presence of deteriorated concrete. A high quality ferrocement should produce a bell like sound and resist moderately severe hammer blows without damage.
### 12.7.3 Surface Preparation for Repair of Damage
#### 12.7.3.1 General
The primary objective is to remove any deteriorated mortar or mortar contaminated with corrosive agents and to provide a surface to which the repair materials can be bonded properly. The rougher the surface, the greater the area available for bonding.
#### 12.7.3.2 Removal of Deteriorated Concrete
As a first step in any repair all disintegrated, unsound, and contaminated repair material shall be removed. Saws and chipping hammers used for conventional concrete shall not be used for ferrocement unless large sections are to be completely removed.
Small areas shall be prepared by hand hammering just hard enough to pulverize deteriorated or cracked mortar, but not to the point of damaging the reinforcing mesh.
A pneumatic needle gun may be used for cleaning out broken ferrocement, opening out cracks, and roughening the surface.
Particles of sound mortar embedded in the mesh need not be removed provided they are small enough not to interfere with the penetration of new mortar and they will not project from the finished surface.
#### 12.7.3.3 Reinforcement
Any loose, scaly corrosion revealed on cleaning out the mortar shall be removed by sandblasting, water jet, airblasting, or vacuum methods.
An alternative method for removing rust is to brush naval jelly or spray dilute phosphoric acid over the repair area and flush thoroughly.
Where the mesh cage has been displaced but is still intact, it may be pushed or jacked back in place and supported securely to withstand the pressure of applying the repair material. Where the reinforcement has been torn, the old mesh shall be laced back to close the opening.
When rods supporting the mesh cage are torn they shall be spliced by a 15 diameter overlap of the partner rod or anchored by hooks.
#### 12.7.3.4 Cleaning
Loose particles and dust residue from hammering or sandblasting shall be air jetted or vacuum cleaned if epoxy or methylmethacrylate (MMA) is the repair material. Water jetting may be used if the repair is to be made with hydraulic cement or latex modified mortar.
If an air jet is used, the compressor shall be equipped with an oil trap to prevent contamination of the surface. Surface oil or dirt shall be removed by trisodium phosphate or other strong detergents.
#### 12.7.3.5 Cracks
Cracks may be cleaned by hammering out the mortar on each side of the crack and replatered with latex mortar.
If opening the crack is not feasible, epoxy or MMA injection systems shall be attempted in accordance with the product directions. The crack shall be cleaned, first with oil free compressed air and small (about 2 by 3 mm) drill holes shall be made at the highest and lowest points in the crack. The surface between the holes shall be sealed with strong coatings or a pressure pad. Catalyzed epoxy or MMA shall be injected at the lower hole until it comes out of the upper hole.
Where a latex cement gout is to be used, the interior of the crack shall be thoroughly saturated with water and allowed to drain.
### 12.7.4 Repair Materials
#### 12.7.4.1 Portland Cement and Sand
Portland cement used for repair shall conform to the requirements of Sec 12.3.1.
Sand which matches that used in the original construction may be used unless the need for the repair arose because of reactive or contaminated sand. Neat portland or blended cement paste shall be used to fill small cracks, and a mortar with fine sand shall be used to fill larger cracks or voids. Both shall be used in combination with latex for thin patches and overlays. Larger cracks shall be coated with a neat cement slurry, then dry packed with a very low water cement ratio mortar.
The addition of latex to portland cement mortar markedly improves bond to the substrate and the tensile strength of the patch. Of the synthetic latexes, polyvinyl acetate and polyvinylidene are unsuitable for wet environments. Acrylics may be used as admixtures to improve bonding and as curing compounds. Acrylic latexes in concentrated form shall be diluted to 10 to 20 per cent solids and then used as the mixing water for the mortar. Latex mortars may be applied to a damp surface, but the patch shall be allowed to dry thoroughly before being immersed in water.
#### 12.7.4.2 Polymer Mortars
Nonlatex polymer mortars shall require the use of surface dried and, preferably, oven dried sand. The monomers have very low viscosity and so shall be mixed with thickening agents to be placed in any area that cannot be sealed tightly. Epoxy resins that are moisture tolerant may be used on damp surfaces.
Care shall be exercised in applying polymers or the promoters and hardeners used with them which are toxic.
#### 12.7.4.3 Admixture
Accelerators may be employed where cement alone is the repair material. Since chloride compounds may promote corrosion, nonchloride accelerators shall be preferred for all ferrocement. Emergency repairs of small areas below the waterline with hot plug, which is neat cement moistened to a putty consistency with a concentrated solution of calcium chloride may be permitted. The hot plug may be carried in the hand or in a plastic bag to the site of the leak, pressed into the hole, and held a few minutes until set. Permit repair shall be accomplished as soon as possible using materials without chlorides.
### 12.7.5 Repair Procedure
#### 12.7.5.1 Mixing
Small quantities of materials required for ferrocement repairs may be hand mixed on flat surface or in a tray using premixed dry ingredients. For large quantities, a plaster or pan mixer rather than a rotating drum type mixer shall be used. For machine mixing, water shall be put in first; then the cement, to form a slurry; then the pozzolan, if used; and finally, enough sand to bring the mortar to the desired degree of workability.
#### 12.7.5.2 Full Depth Repair
When both faces are accessible, a fluid mortar shall be pushed through the mesh cage from one side until an excess appears on the opposite face. This excess shall then be pushed back and finished flush. A vibrating float or trowel may be used to place and finish a very stiff mortar. Pencil type vibrators shall not be used.
#### 12.7.5.3 Partial Depth Patches
The area to be patched shall first be saturated with water, then air blown or blotted free of standing water until only surface-moist. A cement slurry of not more than 0.4 water cement ratio and of paint-like consistency shall be brushed over the whole area and into any openings in the mesh. This shall be immediately followed by a heavily sanded mortar of the same water cement ratio, which shall be vibrated or tamped into the patch and finished flush.
#### 12.7.5.4 Overlays
The substrate shall be prepared in the manner prescribed in Sec 12.7.5.3 for patches. The old surface shall be thoroughly cleaned or scarified by mechanical means and the repair materials shall match the thermal characteristics of the substrate.
Chemical etching shall be followed by mechanical abrasion, unless the surface is flushed with high pressure water jet equipment.
For thin overlays, velocity placement such as spritzing or casting by hand, and shotcreting, shall be used.
#### 12.7.5.5 Shotcrete
Shotcrete may be used in ferrocement repair when a large area is involved. Small, low cost portable plaster pumps operating on the Moyno progressive cavity principle with a rotor inside a stator tube shall be adequate for both original ferrocement construction and repair.
Shotcrete or elastomeric equipment may be used for overlays incorporating additional layers of reinforcing mesh by laminating techniques. Existing surfaces shall be scarified or sandblasted, the first part of mortar spray is applied. An initial application of cement slurry is not needed with shotcrete but a latex or wet to dry epoxy bonding compound may be used to advantage with repairs made with plastering equipment.
#### 12.7.5.6 Curing
Portland cement patches and overlays shall be thoroughly cured unless latex compounds are used to seal the surface and furnish water for hydration. Curing shall be instituted immediately for thin patches and overlays. Several layers of paper or cloth soaked in water and covered with a plastic sheet that is well secured at the edges may be used on patches. A full plastic film covering overlays may be used but it may produce discoloration where it touches the surface.
## 12.8 Testing
### 12.8.1 Test Requirement
Tests and observations that are commonly made during the design, construction, and subsequent service life of concrete structures shall also be applicable to ferrocement structures. The test programme shall include
a) tests on physical, chemical and mechanical properties of the ferrocement ingredients, such as water purity, sieve analysis, mesh strength etc.,
b) control tests for fresh mortar mix, such as slump, air content etc.,
c) tests on the mechanical properties of the hardened ferrocement, such as bending, cracking and fatigue strengths, permeability etc., and
d) in-service condition tests, such as potential for corrosion, cracking, durability etc.
For predicting the mechanical properties of ferrocement, the tests specified in Sec 12.8.2.1 through 12.8.2.4 shall be conducted.
### 12.8.2 Test Methods
#### 12.8.2.1 Compressive Strength and Static Modulus of Elasticity of Mortar
The compressive strength and static modulus of elasticity of the mortar used for the fabrication of ferrocement shall be determined from 75 mm x 150 mm cylinders tested in accordance with ASTM C39-86 and C469-83, respectively.
#### 12.8.2.2 Flexural Strength of Ferrocement
Ferrocement specimens shall be tested as a simply supported beam with third point loading. The span to depth ratio of the beam specimen shall not be less than 20 and its width shall not be less than six times the mesh opening or wire spacing measured at right angles to the span direction.
#### 12.8.2.3 Tensile Properties of the Mesh Reinforcement
Square or rectangular meshes may be tested directly in tension; hexagonal meshes and expanded metal meshes shall be tested only while encapsulated in mortar. In the latter case the tensile test shall be performed on the ferrocement material as described in Sec 12.8.2.4 below.
For square and rectangular meshes, the yield strength, elastic modulus, and ultimate tensile strength shall be obtained from direct tensile tests on samples of wires or flat coupons cut from the mesh. The test shall be in accordance with the following guidelines (see also Fig 6.12.8):
1. The test specimen shall be prepared by embedding both ends of a rectangular coupon of mesh in mortar over a length at least equal to the width of the sample. The mortar embedded ends shall serve as pads for gripping. The free (not embedded) portion of the mesh shall represent the test sample.
2. The width of the test sample shall not be less than six times the mesh opening or wire spacing measured at right angles to the loading direction.
3. The length of the test sample shall be not less than three times its width or 150 mm, whichever is larger.
4. Measurements of elongations (from which strains are to be computed) shall be recorded over half the length of the mesh sample.
5. Yield strain of mesh reinforcement shall be taken as the strain at the intersection of the best straight line fit of the initial portion of the stress strain curve and the best straight line fit of the yielded portion of the stress strain curve, as shown in Fig 6.12.8. The yield stress shall be taken as the stress point on the original stress strain curve at the yield strain found above. The procedure is demonstrated in Fig 6.12.8.
![]()
Fig. 6.12.8 Schematic Description of Mesh Tensile Test Sample and Corresponding Stress-Strain Curve
#### 12.8.2.4 Tensile Test of Ferrocement
Direct tensile tests of ferrocement elements shall be made using a rectangular specimen satisfying the same minimum size requirements at Sec 12.2.3 for the mesh reinforcement. The test specimens shall additionally be reinforced at their ends for gripping. The middle half of the nongripped (free) portion of the test specimen shall be instrumented. A plot of the load elongation curve up to failure shall be used to estimate the effective modulus of the mesh system as well as its yield strength, ultimate strength, and efficiency factor. The yield strain and corresponding stress shall be determined in accordance with the procedure described in Sec 12.8.2.3.
**Related Appendices**
| Appendix D | Calculation of Volume Fraction of Reinforcement |
| ---------- | ---------------------------------------------------------- |
| Appendix E | Common Types and Sizes of Steel Meshes Used in Ferrocement |
# Chapter 2: Loads
Source: https://docs.sayed.app/bnbc2006/part-6-structural-design/chapter-2-loads
## 2.1 INTRODUCTION
### 2.1.1 Scope
This chapter specifies the minimum design forces including dead load, live load, wind and earthquake loads, miscellaneous loads and their various combinations. These loads shall be applicable for the design of buildings and structures in conformance with the general design requirements provided in Chapter 1.
### 2.1.2 Limitations
Provisions of this chapter shall generally be applied to majority of buildings and other structures subject to normally expected loading conditions. For those buildings and structures having unusual geometrical shapes, response characteristics or site locations, or for those subject to special loading including tornadoes, special dynamic or hydrodynamic loads etc., site-specific or case-specific data or analysis may be required to determine the design loads on them. In such cases, and all other cases for which loads are not specified in this chapter, loading information may be obtained from reliable references or specialist advice may be sought. However, such loads shall be applied in compliance with the provisions of other sections of this Code.
## 2.2 DEAD LOADS
### 2.2.1 General
The minimum design dead load for buildings and portions thereof shall be determined in accordance with the provisions of this section. In addition, design of the overall structure and its primary load-resisting systems shall conform to the general design provisions given in Chapter 1.
### 2.2.2 Definition
Dead Load is the vertical load due to the weight of permanent structural and non-structural components of a building such as walls, floors, ceilings, permanent partitions and fixed service equipment etc.
### 2.2.3 Assessment of Dead Load
Dead load for a structural member shall be assessed based on the forces due to:
i) weight of the member itself,
ii) weight of all materials of construction incorporated into the building to be supported permanently by the member,
iii) weight of permanent partitions,
iv) weight of fixed service equipment, and
v) net effect of prestressing.
### 2.2.4 Weight of Materials and Constructions
In estimating dead loads, the actual weights of materials and constructions shall be used, provided that in the absence of definite information, the weights given in Tables 6.2.1 and 6.2.2 shall be assumed for the purposes of design.
**Table 6.2.1 Unit Weight of Basic Materials**
| Material | Unit Weight (kN/m³) | Material | Unit Weight (kN/m³) |
| :---------------------------------------- | :-----------------: | :-------------- | :-----------------: |
| Aluminium | 27.0 | Granite, Basalt | 26.4 |
| Asphalt | 21.2 | Iron - cast | 70.7 |
| Brass | 83.6 | - wrought | 75.4 |
| Bronze | 87.7 | Lead | 111.0 |
| Brick | 18.9 | Limestone | 24.5 |
| Cement | 14.7 | Marble | 26.4 |
| Coal, loose | 8.8 | Sand, dry | 15.7 |
| Concrete - stone aggregate (unreinforced) | 22.8\* | Sandstone | 22.6 |
| Concrete - brick aggregate (unreinforced) | 20.4\* | Slate | 28.3 |
| Copper | 86.4 | Steel | 77.0 |
| Cork, normal | 1.7 | Timber | 5.9-11.0 |
| Cork, compressed | 3.7 | Zinc | 70.0 |
| Glass, window (soda-lime) | 25.5 | | |
\* for reinforced concrete, add 0.63 kN/m³ for each 1% by volume of main reinforcement
**Table 6.2.2 Weight of Construction Materials**
| Material | Weight per Unit Area (kN/m²) | Material | Weight per Unit Area (kN/m²) |
| :--------------------------------------------------------------------------------------------------- | :--------------------------: | :------------------------------------------------------------------- | :--------------------------: |
| **Floor** | | **Roof (contd.)** | |
| Asphalt, 25 mm thick | 0.526 | Tiles - terra-cotta (French pattern) | 0.575 |
| Clay tiling, 13 mm thick | 0.268 | Tiles - concrete, 25 mm thick | 0.527 |
| Concrete slab (stone aggregate)\* - solid, 100 mm thick | 2.360 | Tiles - clay tiles | 0.6-0.9 |
| Concrete slab (stone aggregate)\* - solid, 150 mm thick | 3.540 | **Walls and Partitions** | |
| Galvanized steel floor deck (excl. topping) | 0.147-0.383 | Acrylic resin sheet, flat, per mm thickness | 0.012 |
| Magnesium oxychloride - normal (sawdust filler), 25 mm thick | 0.345 | Asbestos cement sheeting - 4.5 mm thick | 0.072 |
| Magnesium oxychloride - heavy duty (mineral filler), 25 mm thick | 0.527 | Asbestos cement sheeting - 6.0 mm thick | 0.106 |
| Terrazzo paving 16 mm thick | 0.431 | Brick masonry work, excl. plaster - burnt clay, per 100 mm thickness | 1.910 |
| **Roof** | | Brick masonry work, excl. plaster - sand-lime, per 100 mm thickness | 1.980 |
| Acrylic resin sheet, corrugated - 3 mm thick, standard corrugations | 0.043 | Concrete (stone aggregate)\* - 100 mm thick | 2.360 |
| Acrylic resin sheet, corrugated - 3 mm thick, deep corrugations | 0.062 | Concrete (stone aggregate)\* - 150 mm thick | 3.540 |
| Asbestos cement, corrugated sheeting (incl. lap and fastenings) - 6 mm thick (standard corrugations) | 0.134 | Concrete (stone aggregate)\* - 250 mm thick | 5.900 |
| Asbestos cement, corrugated sheeting (incl. lap and fastenings) - 6 mm thick (deep corrugations) | 0.158 | Fibre insulation board, per 10 mm thickness | 0.034 |
| Aluminium, corrugated sheeting (incl. lap and fastenings) - 1.2 mm thick | 0.048 | Fibrous plaster board, per 10 mm thickness | 0.092 |
| Aluminium, corrugated sheeting (incl. lap and fastenings) - 0.8 mm thick | 0.028 | Glass, per 10 mm thickness | 0.269 |
| Aluminium, corrugated sheeting (incl. lap and fastenings) - 0.6 mm thick | 0.024 | Hardboard, per 10 mm thickness | 0.961 |
| Aluminium sheet (plain) - 1.2 mm thick | 0.033 | Particle or flake board, per 10 mm thickness | 0.075 |
| Aluminium sheet (plain) - 1.0 mm thick | 0.024 | Plaster board, per 10 mm thickness | 0.092 |
| Aluminium sheet (plain) - 0.8 mm thick | 0.019 | Plywood, per 10 mm thickness | 0.061 |
| Bituminous felt (5 ply) and gravel | 0.431 | **Ceiling** | |
| Slates - 4.7 mm thick | 0.335 | Fibrous plaster, 10 mm thick | 0.081 |
| Slates - 9.5 mm thick | 0.671 | Cement plaster, 13 mm thick | 0.287 |
| Steel sheet, flat galvanized - 1.00 mm thick | 0.082 | Suspended metal lath and plaster (two faced incl. studding) | 0.480 |
| Steel sheet, flat galvanized - 0.80 mm thick | 0.067 | **Miscellaneous** | |
| Steel sheet, flat galvanized - 0.60 mm thick | 0.053 | Felt (insulating), per 10 mm thickness | 0.019 |
| Steel, galvanized std. corrugated sheeting (incl. lap and fastenings) - 1.0 mm thick | 0.120 | Plaster - cement, per 10 mm thickness | 0.230 |
| Steel, galvanized std. corrugated sheeting (incl. lap and fastenings) - 0.8 mm thick | 0.096 | Plaster - lime, per 10 mm thickness | 0.191 |
| Steel, galvanized std. corrugated sheeting (incl. lap and fastenings) - 0.6 mm thick | 0.077 | PVC sheet, per 10 mm thickness | 0.153 |
| | | Rubber paving, per 10 mm thickness | 0.151 |
| | | Terra-cotta Hollow Block Masonry - 75 mm thick | 0.671 |
| | | Terra-cotta Hollow Block Masonry - 100 mm thick | 0.995 |
| | | Terra-cotta Hollow Block Masonry - 150 mm thick | 1.388 |
\* for brick aggregate, 90% of the listed values may be used.
### 2.2.5 Weight of Permanent Partitions
When partition walls are indicated on the plans, their weight shall be considered as dead load acting as concentrated line loads in their actual positions on the floor. The loads due to anticipated partition walls, which are not indicated on the plans, shall be treated as live loads and determined in accordance with Sec 2.3.3.3.
### 2.2.6 Weight of Fixed Service Equipment
Weights of fixed service equipment and other permanent machinery, such as electrical feeders and other machinery, heating, ventilating and air-conditioning systems, lifts and escalators, plumbing stacks and risers etc. shall be included as dead load whenever such equipment are supported by structural members.
### 2.2.7 Additional Loads
In evaluating the final dead loads on a structural member for design purposes, allowances shall be made for additional loads resulting from the (i) difference between the prescribed and the actual weights of the members and construction materials; (ii) inclusion of future installations; (iii) changes in occupancy or use of buildings; and (iv) inclusion of structural and non-structural members not covered in Sec 2.2.2 and 2.2.3.
## 2.3 LIVE LOADS
### 2.3.1 General
The live loads used for the structural design of floors, roof and the supporting members shall be the greatest applied loads arising from the intended use or occupancy of the building, or from the stacking of materials and the use of equipment and propping during construction, but shall not be less than the minimum design live loads set out by the provisions of this section. For the design of structural members for forces including live loads, requirements of the relevant sections of Chapter 1 shall also be fulfilled.
### 2.3.2 Definition
Live load is the load superimposed by the use or occupancy of the building not including the environmental loads such as wind load, rain load, earthquake load or dead load.
### 2.3.3 Minimum Floor Live Loads
The minimum floor live loads shall be the greatest actual imposed loads resulting from the intended use or occupancy of the floor, and shall not be less than the uniformly distributed load patterns specified in Sec 2.3.3.1 or the concentrated loads specified in Sec 2.3.3.2 whichever produces the most critical effect. The live loads shall be assumed to act vertically upon the area projected on a horizontal plane.
#### 2.3.3.1 Uniformly Distributed Loads
The uniformly distributed load shall not be less than the values listed in Table 6.2.3, reduced as may be specified in Sec 2.3.9, applied uniformly over the entire area of the floor, or any portion thereof to produce the most adverse effects in the member concerned.
#### 2.3.3.2 Concentrated Loads
The concentrated load to be applied non-concurrently with the uniformly distributed load given in Sec 2.3.3.1, shall not be less than that listed in Table 6.2.3. Unless otherwise specified in Table 6.2.3 or in the following paragraph, the concentrated load shall be applied over an area of 300 mm x 300 mm and shall be located so as to produce the maximum stress conditions in the structural members.
In areas where vehicles are used or stored, such as car parking garages, ramps, repair shops etc., provision shall be made for concentrated loads consisting of two or more loads spaced nominally 1.5 m on centres in absence of the uniform live loads. Each load shall be 40 per cent of the gross weight of the maximum size
**Table 6.2.3 Live Loads for Various Occupancies**
| Occupancy | Use of floor | *w* (kN/m²) | *P* (kN) |
| :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :----------------------------------------------------------------------------------------- | :---------: | :------: |
| **RESIDENTIAL (Occupancy - A)** — Hotel, hostel, boarding house, flat and apartment, bungalow | | | |
| One- or two-family dwellings | 1. Room, internal corridor, private stair | 2.0 | 1.8 |
| | 2. External stair and corridor | 3.0 | 2.7 |
| Other residential | 1. Bed room, living room, bath room, toilet, dressing room | 2.0 | 1.8 |
| | 2. Office room | 2.5 | 2.7 |
| | 3. Cafeteria, restaurant, kitchen, laundry, lobby, lounge, game room, dining hall, balcony | 3.0 | 4.5 |
| | 4. Corridor, retail store, staircase | 4.0 | 4.5 |
| | 5. Store room | 5.0 | 4.5 |
| | 6. Garage, car parking floor, ramp (See Occupancy - K) | - | - |
| **EDUCATIONAL, INSTITUTIONAL & HEALTH-CARE (Occupancy - B, C & D)** — School, college, university, penal and mental institutions, orphanage, child care home, normal and emergency medical facilities, hospital, clinic etc. | 1. Bed room, dressing room, toilet, hospital ward and cabin, cell blocks of jail | 2.0 | 1.8 |
| | 2. Office room, staff room | 2.5 | 2.7 |
| | 3. X-ray room, operating room, utility room, reading room without book storage | 2.5 | 4.5 |
| | 4. Class room, lecture room, lounge, cafeteria, restaurant | 3.0 | 2.7 |
| | 5. Laboratory, kitchen, laundry | 3.0 | 4.5 |
| | 6. Balcony, corridor, lobby, reading room with book storage, staircase | 4.0 | 4.5 |
| | 7. Assembly area, fire escape, store room, projection room | 5.0 | 4.5 |
| | 8. Stack room for book | 6.5 (3) | 7.0 |
| **ASSEMBLY (Occupancy - E)** — Library, auditorium, cinema, lecture hall, restaurant, bar, mosque, church (E1-E4) | 1. Assembly room: with fixed seat | 3.0 | 2.7 |
| | 1. Assembly room: without fixed seat | 5.0 | 4.5 |
| | 2. Stages and projection room | 5.0 | 4.5 |
| | 3. Library: Reading room - without book storage | 2.5 | 4.5 |
| | 3. Library: Reading room - with book storage | 4.0 | 4.5 |
| | 3. Library: Stack room for book | 6.5 (3) | 7.0 |
| Stadium, art gallery, grand stand, museum, gymnasium (E5) | 1. With fixed seats | 3.0 | 2.7 |
| | 2. Without fixed seats | 5.0 | 4.5 |
| | 3. Corridor, stair and passage way | 5.0 | 4.5 |
| **BUSINESS AND MERCANTILE (Occupancy - F)** — Office, bank, laboratory etc. | 1. General office room, banking hall | 3.0 | 9.0 (5) |
| | 2. Laboratory, kitchen | 3.0 | 4.5 |
| | 3. Computer, business machine room | 3.5 | 9.0 (5) |
| | 4. File room, filing and storage space | 6.0 | 4.5 |
| | 5. Vaults in office and bank | 5.0 | 4.5 |
| | 6. Telephone exchange | 6.0 | 4.5 |
| Shop, market, departmental store | 1. Retail store | 4.0 | 3.6 |
| | 2. Wholesale store | 6.0 | 13.0 (5) |
| | 3. Storage: light | 6.0 | 4.5 |
| | 3. Storage: heavy | 12.0 | 14.0 (5) |
| **INDUSTRIAL, STORAGE & HAZARDOUS (Occupancy - G, H & J)** — Workshop, factory, warehouse | 1. Light workroom without storage | 3.0 | 2.7 |
| | 2. Machinery hall & circulation area | 4.0 | 4.5 |
| | 3. Factory, workshop etc. | 5.0 | 4.5 |
| | 4. Manufacturing: light | 6.0 | 4.5 |
| | 4. Manufacturing: heavy | 12.0 | 9.0 (5) |
| | 4. Manufacturing: ice | 15.0 | 9.0 (5) |
| | 5. Printing plant: Press room | 7.0 | 11.0 (5) |
| | 5. Printing plant: Composing and linotype room | 5.0 | 9.0 (5) |
| | 5. Printing plant: Paper storage room | 12.0 | 9.0 (5) |
| | 6. Motor room, fan room etc. including the weight of machinery | 7.5 | 4.5 |
| | 7. Cold storage, grain storage | 15.0 | 9.0 (5) |
| | 8. Storage warehouses: light | 6.0 | 4.5 (5) |
| | 8. Storage warehouses: heavy | 12.0 | 9.0 |
| | 9. Foundries | 20.0 | 12.0 |
| **MISCELLANEOUS (Occupancy - K)** — Garage, car park, vehicle access ramp | 1. Repair workshop for all types of vehicles | 5.0 | 9.0 |
| | 2. Driveway, ramp and parking for vehicles with mass > 2500 kg | 5.0 | - (4) |
| | 3. Car parking and ramp for passenger car and light vehicles having mass ≤ 2500 kg | 2.5 | - (4) |
| **ALL OCCUPANCIES (Occupancy - A, H, J, K)** — Special loads and Miscellaneous live loads (if not specified above) | 1. Bed room, toilet, dressing room | 2.0 | 1.8 |
| | 2. Office room, staff room | 2.5 | 2.7 |
| | 3. Kitchen, laundry, lounge, game room, cafeteria, restaurant | 3.0 | 4.5 |
| | 4. Balcony, corridor, passage way, retail store, staircase | 4.0 | 4.5 |
| | 5. Assembly area, store room, fire escape, projection room | 5.0 | 4.5 |
| | 6. Drill room, drill hall | 5.0 | 9.0 |
| | 7. Armories, boiler room and machine room including weight of machinery | 7.5 | 4.5 |
| | 8. Airport hangars | 7.0 | 12.0 (5) |
Note: (1) *w*: Uniformly distributed load in kN/m². This load shall not be applied simultaneously with the concentrated load, *P*.
(2) *P*: A single concentrated load, in kN, assumed to act over an area of 300 mm x 300 mm unless otherwise specified in Note (5) below. Except as indicated by Note (5), these concentrated loads need not be considered for the floors capable of laterally distributing the load, e.g. reinforced concrete slabs.
(3) Use a distributed load of 2.4 kN/m² for each metre of stack height but not less than 6.5 kN/m².
(4) See Sec 2.3.3.2 for values, numbers, and spacing of these concentrated loads.
(5) These loads shall be applied over an area of 750 mm x 750 mm on all types of floors including reinforced concrete slab.
In areas where vehicles are used or stored, such as car parking garages, ramps, repair shops etc., provision shall be made for concentrated loads consisting of two or more loads spaced nominally 1.5 m on centres in absence of the uniform live loads. Each load shall be 40 per cent of the gross weight of the maximum size vehicle to be accommodated and applied over an area of 750 mm x 750 mm. For the storage of private or pleasure-type vehicles without repair or fuelling, floors shall be investigated in the absence of the uniform live load, for a minimum concentrated wheel load of 9 kN spaced 1.5 m on centres, applied over an area of 750 mm x 750 mm. The uniform live loads for these cases are provided in Table 6.2.3. The condition of concentrated or uniform live load producing the greater stresses shall govern.
#### 2.3.3.3 Provision for Partition Walls
When partitions, not indicated on the plans, are anticipated to be placed on the floors, their weight shall be included as an additional live load acting as concentrated line loads in an arrangement producing the most severe effect on the floor, unless it can be shown that a more favourable arrangement of the partitions shall prevail during the future use of the floor.
In the case of light partitions, wherein the total weight per metre run is not greater than 5.5 kN, a uniformly distributed live load may be applied on the floor in lieu of the concentrated line loads specified above. Such uniform live load per square metre shall be at least 33% of the weight per metre run of the partitions, subject to a minimum of 1.2 kN/m².
#### 2.3.3.4 More than One Occupancy
Where an area of a floor is intended for two or more occupancies at different times, the value to be used from Table 6.2.3 shall be the greatest value for any of the occupancies concerned.
### 2.3.4 Minimum Roof Live Loads
Roof live loads shall be assumed to act vertically over the area projected by the roof or any portion of it upon a horizontal plane, and shall be determined as specified in the following sections:
#### 2.3.4.1 Regular Purpose - Flat, Pitched and Curved Roofs
Live loads on regular purpose roofs shall be the greatest applied loads produced during use by movable objects such as planters and people, and those induced during maintenance by workers, equipment and materials but shall not be less than those given in Table 6.2.4.
**Table 6.2.4 Minimum Roof Live Loads (1)**
| Type | Type and Slope of Roof | Distributed Load, kN/m² | Concentrated Load, kN |
| :--: | :---------------------------------------------------------------------------------------------- | :--------------------------------------------------------------: | :-------------------: |
| I | Flat roof (slope = 0) | 1.5 | 1.8 |
| II | 1. Pitched or sloped roof (0 \< slope \< 1/3); 2. Arched roof or dome (rise \< 1/8 span) | 1.0 | 0.9 |
| III | 1. Pitched or sloped roof (1/3 ≤ slope \< 1.0); 2. Arched roof or dome (1/8 ≤ rise \< 3/8 span) | 0.8 | 0.9 |
| IV | 1. Pitched or sloped roof (slope ≥ 1.0); 2. Arched roof or dome (rise ≥ 3/8 span) | 0.6 | 0.9 |
| V | Greenhouse, and agriculture buildings | 0.5 | 0.9 |
| VI | Canopies and awnings, except those with cloth covers | same as given in I through IV above based on the type and slope. | |
Note: (1) Greater of this load and rain load as specified in Sec 2.6.3 shall be taken as the design live load for roof. The distributed load shall be applied over the area of the roof projected upon a horizontal plane and shall not be applied simultaneously with the concentrated load. The concentrated load shall be assumed to act upon a 300 mm x 300 mm area and need not be considered for roofs capable of laterally distributing the load, e.g. reinforced concrete slabs.
#### 2.3.4.2 Special Purpose Roofs
For special purpose roofs, live loads shall be estimated based on the actual weight depending on the type of use, but shall not be less than the following values:
a) roofs used for promenade purposes - 3.0 kN/m²
b) roofs used for assembly purposes - 5.0 kN/m²
c) roofs used for gardens - 5.0 kN/m²
d) roofs used for other special purposes - to be determined as per Sec 2.3.5
#### 2.3.4.3 Accessible Roof Supporting Members
Roof trusses or any other primary roof supporting member beneath which a full ceiling is not provided, shall be capable of supporting safely, in addition to other roof loads, a concentrated load at the locations as specified below:
a) Industrial, Storage and Garage Buildings - Any single panel point of the lower chord of a roof truss, or any point of other primary roof supporting member - 9.0 kN
b) Building with Other Occupancies - Any single panel point of the lower chord of a roof truss, or any point of other primary roof supporting member - 1.3 kN
### 2.3.5 Loads Not Specified
Live loads, not specified for uses or occupancies in Sec 2.3.3.1 and 2.3.3.2, shall be determined from loads resulting from:
a) weight of the probable assembly of persons;
b) weight of the probable accumulation of equipment and furniture, and
c) weight of the probable storage of materials.
### 2.3.6 Partial Loading and Other Loading Arrangements
The full intensity of the appropriately reduced live load applied only to a portion of the length or area of a structure or member shall be considered, if it produces a more unfavourable effect than the same intensity applied over the full length or area of the structure or member.
Where uniformly distributed live loads are used in the design of continuous members and their supports, consideration shall be given to full dead load on all spans in combination with full live loads on adjacent spans and on alternate spans whichever produces a more unfavourable effect.
### 2.3.7 Other Live Loads
Live loads on miscellaneous structures and components, such as handrails and supporting members, parapets and balustrades, ceilings, skylights and supports, and the like, shall be determined from the analysis of the actual loads on them, but shall not be less than those given in Table 6.2.5.
**Table 6.2.5 Miscellaneous Live Loads**
| Structural Member or Component | Live Load (1) (kN/m) |
| :---------------------------------------------------------------------------------------------------------------------- | :------------------: |
| 1. Handrails, parapets and supports: | |
| a) Light access stairs, gangways etc. - i) width ≤ 0.6 m | 0.25 |
| a) Light access stairs, gangways etc. - ii) width > 0.6 m | 0.35 |
| b) Staircases other than in (a) above, ramps, balconies: i) Single dwelling and private | 0.35 |
| b) ii) Staircases in residential buildings | 0.35 |
| b) iii) Balconies or portion thereof, stands etc. having fixed seats within 0.55 m of the barrier | 1.5 |
| b) iv) Public assembly buildings including theatres, cinemas, assembly halls, stadiums, mosques, churches, schools etc. | 3.0 |
| b) v) Buildings and occupancies other than (i) through (iv) above | 0.75 |
| 2. Vehicle barriers for car parks and ramps: a) For vehicles having gross mass ≤ 2500 kg | 100 (2) |
| 2. b) For vehicles having gross mass > 2500 kg | 165 (2) |
| 2. c) For ramps of car parks etc. | see note (3) |
Note: (1) These loads shall be applied non-concurrently along horizontal and vertical directions, except as specified in note (2) below.
(2) These loads shall be applied only in the horizontal direction, uniformly distributed over any length of 1.5 m of a barrier and shall be considered to act at bumper height. For case 2(a) bumper height may be taken as 375 mm above floor level.
(3) Barriers to access ramps of car parks shall be designed for horizontal forces equal to 50% of those given in 2(a) and 2(b) applied at a level of 610 mm above the ramp. Barriers to straight exit ramps exceeding 20 m in length shall be designed for horizontal forces equal to twice the values given in 2(a) and 2(b).
### 2.3.8 Impact and Dynamic Loads
The live loads specified in Sec 2.3.3 shall be assumed to include allowances for impacts arising from normal uses only. However, forces imposed by unusual vibrations and impacts resulting from the operation of installed machinery and equipment shall be determined separately and treated as additional live loads. Live loads due to vibration or impact shall be determined by dynamic analysis of the supporting member or structure including foundations, or from the recommended values supplied by the manufacture of the particular equipment or machinery. In absence of a definite information, values listed in Table 6.2.6 for some common equipment, shall be used for design purposes.
**Table 6.2.6 Minimum Live Loads on Supports and Connections of Equipment due to Impact (1)**
| Equipment or Machinery | Additional load due to impact — Vertical | Additional load due to impact — Horizontal |
| :------------------------------------------------ | :--------------------------------------: | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 1. Lifts, hoists and related operating machinery | 100% | — |
| 2. Light machinery (shaft or motor driven) | 20% | — |
| 3. Reciprocating machinery, or power driven units | 50% | — |
| 4. Hangers supporting floors and balconies | 33% | — |
| 5. Cranes: a) Electric overhead cranes | 25% of maximum wheel load | i) Transverse to the rail: 20% of the weight of trolley and lifted load only, applied one-half at the top of each rail. ii) Along the rail: 10% of maximum wheel load applied at the top of each rail |
| 5. b) Manually operated cranes | 50% of the values in (a) above | 50% of the values in (a) above |
| 5. c) Cab-operated travelling cranes | 25% | — |
— Not applicable
Note: (1) All these loads shall be increased if so recommended by the manufacturer. For machinery and equipment not listed, impact loads shall be those recommended by the manufacturers, or determined by dynamic analysis.
### 2.3.9 Reduction of Live Loads
Reduction of live load is permitted for primary structural members supporting floor or roof, including beam, girder, truss, flat slab, flat plate, column, pier, footing and the like. Where applicable, the reduced live load on a primary structural member shall be obtained by multiplying the corresponding unreduced uniformly distributed live load with an appropriate live load reduction factor, **R** as listed in Table 6.2.7 and set forth in Sec 2.3.9.1.
#### 2.3.9.1 Load Groups
All possible live loads applied on floors and roof of a building due to various occupancies and uses, shall be divided into three load groups as described below for determining the appropriate live load reduction factors.
a) **Load Group 1:** Uniformly distributed live loads arising from the occupancies and uses of (i) assembly occupancies or areas with uniformly distributed live load of 5.0 kN/m² or less, (ii) machinery and equipment for which specific live load allowances have been made, (iii) special roof live load as described in Sec 2.3.4.2, and (iv) printing plants, vaults, strong rooms and armouries, shall be classified under Load Group 1. Reduction of live load shall not be allowed for members or portions thereof under this load group and a reduction factor, **R = 1.0** shall be applied for such cases.
b) **Load Group 2:** Uniformly distributed live loads resulting from occupancies or uses of (i) assembly areas with uniformly distributed live load greater than 5.0 kN/m², and (ii) storage, mercantile, industrial and retail stores, shall be classified under Load Group 2. Live load reduction factor, $1.0 \leq R \leq 0.7$ shall be applied to this load group depending on the tributary area of the floors or roof supported by the member as specified in Sec 2.3.9.3.
c) **Load Group 3:** Uniformly distributed live loads arising due to all other occupancies and uses except those of Load Group 1 and Load Group 2, shall be grouped into Load Group 3. Live load reduction factor, $1.0 \leq R \leq 0.5$ as specified in the Sec 2.3.9.3, shall be applied to tributary areas under this load group.
#### 2.3.9.2 Tributary Area
The tributary area of a structural member supporting floors or roof shall be determined as follows:
a) **Tributary Area for Wall, Column, Pier, Footing and the like:** Tributary areas of these members shall consist of portions of the areas of all floors, roof or combination thereof that contribute live loads to the member concerned.
b) **Tributary Area for Beam, Girder, Flat plate and Flat slab:** Tributary area for such a member shall consist of the portion of the roof or a floor at any single level that contributes loads to the member concerned.
**Table 6.2.7 Live Load Reduction Factors for Various Occupancies and Uses**
| Load Group | Occupancy or Use | Tributary Area (floor, or roof, or combination) $A_t$ (m²) | Live Load Reduction Factor, R |
| :--------: | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :-------------------------------------------------------------: | :------------------------------------------------------------------------: |
| 1 | a) Assembly areas with uniformly distributed live load of 5.0 kN/m² or less. b) Live loads from machinery and equipment for which specific load allowance has been made. c) Special roof live loads as specified in Sec 2.3.4.2. d) Printing plants, vaults, strong room and armouries | all | 1.0 |
| 2 | a) Assembly areas with uniformly distributed live load greater than 5.0 kN/m². b) Storage, mercantile, industrial, parking garage, retail stores | ≤50 / 60 / 80 / 100 / 120 / 140 / 280 / 220 / 300 / 400 / ≥800 | 1.00 / 0.97 / 0.92 / 0.88 / 0.86 / 0.84 / 0.81 / 0.79 / 0.76 / 0.74 / 0.70 |
| 3 | a) Uniformly distributed live loads from all occupancies and uses except those listed in load groups 1 and 2 above. | \<25 / 25-30 / 40 / 50 / 60 / 80 / 100 / 120 / 140 / 180 / ≥220 | 1.00 / 0.90 / 0.84 / 0.78 / 0.73 / 0.67 / 0.62 / 0.59 / 0.57 / 0.53 / 0.50 |
Table 6.2.7, Load Group 2: the tributary-area sequence reads 50/60/80/100/120/**140/280/220**/300/400/≥800 in the source page image itself (page 6-26). Independently re-verified directly against page\_279.png: the digits are unambiguously "280" (not 180, 208, or any other misreading), printed out of numerical order between 140 and 220. This is transcribed verbatim as it appears in the source; it is likely a typesetting error in the original gazette (compare the strictly increasing sequence in Load Group 3), not an extraction artifact.
Note: (1) $A_t$ = sum of all tributary areas with loads from any one load group (i.e. Load Group 1, 2 or 3).
(2) Linear interpolation may be made to obtain values of R lying between the listed values.
(3) Live load reduction factor, R is based on the relations:
$$
R = 0.6 + \sqrt{8/A_t} \text{ for Load Group 2}
$$
$$
R = 0.25 + \sqrt{14/A_t} \text{ for Load Group 3}
$$
#### 2.3.9.3 Determination of Reduced Live Load
The value of the live load reduction factor, R shall depend on the load group specified in Sec 2.3.9.1 and on the tributary area of the floor or the roof and combination thereof supported by a primary structural member. The reduced live load on a structural member shall be determined using the following steps:
a) Portions of the tributary area pertaining to each of the three load groups specified in Sec 2.3.9.1 shall be identified and summed up, and a value of the reduction factor R shall be obtained from Table 6.2.7 corresponding to each portion of the tributary area,
b) The reduced live loads or load intensities shall then be obtained for each load group by multiplying the unreduced live loads or load intensities by the corresponding reduction factors, and finally,
c) The total reduced live load on a structural member shall be determined by summing up the reduced live loads from each load group.
## 2.4 WIND LOADS
### 2.4.1 General
The minimum design wind load on buildings and components thereof, shall be determined based on the velocity of the wind, the shape and size of the building and the terrain exposure condition of the site as set forth by the provisions of this section. For the overall design of structures, the general design requirements as specified in Chapter 1 shall also be fulfilled.
#### 2.4.1.1 Scope
Provisions of this section shall apply to the calculation of design wind loads for the primary framing systems and for the individual structural components and cladding of buildings. The design wind load shall include the effects of the sustained wind velocity component and the fluctuating component due to gusts. For slender buildings, the design wind load shall also include additional loading effects due to wind induced vibrations of the building.
#### 2.4.1.2 Limitations
Provisions of this section shall include forces due to along-wind response of regular-shaped buildings, caused by the common wind-storms including cyclones, thunder-storms and norwesters. However, the following cases shall remain beyond the scope of these provisions:
a) forces due to cross-wind response of buildings and structures,
b) forces, such as torsion etc. generated due to unusual or unsymmetrical geometry of the building, and
c) forces generated due to special types of winds, such as tornadoes.
For calculation of wind loads arising due to the above special cases and for buildings requiring more accurate loading information, reference shall be made to reliable literature pertaining to these loads, or specialist advice shall be sought.
### 2.4.2 Definitions
The following definitions shall apply only to the provisions of Sec 2.4.
**AWNINGS (e.g. PORCH COVER):** A roof-like structure, usually of limited extent, projecting from a wall of a building.
**BASIC WIND SPEED, $V_b$:** Fastest-mile wind speed in km/h corresponding to the level of 10 metres above the ground of terrain Exposure-B defined in Sec 2.4.4 and associated with an annual probability of occurrence of 0.02.
**BUILDINGS:** Structures that enclose a space and are used for various occupancies.
**CANOPY:** A roof adjacent to or attached to a building, generally not enclosed by walls.
**COMPONENTS AND CLADDING:** Structural elements that are either directly loaded by the wind or receive wind loads originating at relatively close locations and transfer those loads to the primary framing system. Examples include curtain walls, exterior glass windows and panels, roof sheeting, purlins, grits, studs, and roof trusses.
**CYCLONE:** An intense low-pressure centre accompanied by heavy rain and gale-force winds. It forms over warm tropical oceans and decays rapidly over land.
**DESIGN WIND PRESSURES, $p$:** Equivalent static pressure due to wind including gusts to be used in the determination of wind loads for buildings. The pressure shall be assumed to act in a direction normal to the surface considered and is denoted as:
$p_z$ = pressure that varies with height in accordance with the sustained wind pressure $q_z$ evaluated at height $z$, or
$p_h$ = pressure that is uniform with respect to height as determined by the sustained wind pressure $q_h$ evaluated at mean roof height $h$.
**ENCLOSED BUILDING:** Buildings which have full perimeter wall (nominally sealed) from floor to roof level.
**ESSENTIAL FACILITIES:** Buildings and structures which are necessary to remain functional during an emergency or a post disaster period.
**FASTEST-MILE WIND SPEED:** The highest sustained average wind speed in km/h based on the time required for a mile-long sample of air to pass a fixed point.
**FREE STANDING ROOF:** A roof (of any type) with no enclosing walls underneath, e.g. freestanding carport.
**FREESTANDING WALLS:** Walls which are exposed to the wind on both sides, with no roof attached, e.g. fences.
**GABLED FRAME:** A rigid frame having vertical side members and a sloped top with a ridge.
**GRADIENT HEIGHT:** Height from the mean ground level above which the variation of wind speed with height need not be considered.
**HOARDING:** Free standing (rectangular) signboards, etc., supported clear of the ground.
**ISOTACH:** A line on a map joining points of equal wind speed.
**MOONSCAPE ROOF:** A planar roof with no ridge, which has a constant slope.
**OPENINGS:** Apertures or holes in the exterior walls of a building or structure. Doors or other openings in exterior walls shall be considered as openings unless such openings and their frames are specifically detailed and designed to resist the wind loads in accordance with the provisions of this section.
**PITCHED ROOF:** A bi-fold, bi-planar roof with a ridge at its highest point.
**PRESSURE:** Air pressure in excess of ambient. Negative values are less than ambient and positive values exceed ambient. Net pressures act normal to a surface in the specified direction.
**PRIMARY FRAMING SYSTEM:** An assemblage of major structural elements assigned to provide support for secondary members and cladding. The system primarily receives wind loading from relatively remote locations. Examples include rigid and braced frames, space trusses, roof and floor diaphragms, shear walls, and rod-braced frames.
**SLENDER BUILDINGS AND STRUCTURES:** Buildings and structures having a height exceeding five times the least horizontal dimension, or a fundamental natural frequency less than 1.0 Hz. For those cases in which the horizontal dimensions vary with height, the least horizontal dimension at mid-height shall be used.
**STRUCTURES:** See Sec 1.2.2.
**STRUCTURE IMPORTANCE COEFFICIENT, $C_I$:** A factor that accounts for the degree of hazard to human life and damage to property.
**SUSTAINED WIND PRESSURE, $q$:** The theoretically computed incident pressure of a uniform air stream (fastest-mile speed) of known density, evaluated at a given height above ground level, for a specific terrain exposure condition and for a known occupancy of a building.
**TERRAIN:** The surface roughness condition when considering the size and arrangement of obstructions to wind.
**TOPOGRAPHY:** Major land surface features comprising hills, valleys and plains which strongly influence wind flow patterns.
**TORNADO:** A violently rotating column of air, pendant from the base of a connective cloud, and often observable as a funnel cloud attached to the cloud base.
**TRIBUTARY AREA:** That portion of the surface area receiving wind loads assigned to be supported by the structural element considered.
**TROUGH ROOF:** A bi-fold, bi-planar roof with a valley at its lowest point.
**UNENCLOSED BUILDING OR STOREY:** A building or storey which has 85% or more openings on all sides.
### 2.4.3 Symbols and Notation
The following symbols and notation shall apply to the provisions of Sec 2.4 only:
| Symbol | Definition |
| :------------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| $A$ | tributary area, square metres. |
| $\overline{A}$ | area of other structures or components and cladding thereof projected on a plane normal to wind direction, square metres. |
| $a$ | width of pressure coefficient zone used in Fig 6.2.7 and 6.2.8, metres |
| $B$ | horizontal dimension of buildings and structures measured normal to wind direction, metres. |
| $c$ | average horizontal dimension of the building or structure in a direction normal to the wind, metres. |
| $C_c$ | velocity-to-pressure conversion coefficient = $47.2 \times 10^{-6}$ |
| $C_G$ | gust coefficient |
| $C_I$ | structure importance coefficient |
| $C_p$ | pressure coefficient to be used for determination of wind loads on buildings and structures. |
| | $C_{pe}$ external pressure coefficients for surfaces of buildings and structures to be used for wind loads on primary framing systems using Method 1 in Sec 2.4.6.4 (a). |
| | $\overline{C_p}$ overall pressure coefficient for buildings and structures to be used for wind loads on primary framing systems using Method 2 in Sec 2.4.6.4 (b). |
| $C'_{pe}$ | external peak pressure coefficients to be used for wind loads on building components and cladding. |
| $C'_{pi}$ | internal peak pressure coefficient to be used for wind loads on buildings and components. |
| $C_t$ | local topographic coefficient given in Sec 2.4.6.8. |
| $C_z$ | combined height and exposure coefficient for a building at height $z$ above ground |
| $D$ | diameter of a circular structure or member, metres |
| $d$ | diameter of a circular structure or member, metres |
| $D'$ | depth of protruding elements (ribs or spoilers), metres |
| $D_o$ | surface drag coefficient given in Table 6.2.12. |
| $f$ | fundamental frequency of buildings or structures in a direction parallel to the wind, Hz |
| $F_1, F_2$ | design wind forces on primary framing system, kN |
| $F'$ | design wind forces on components and cladding, kN |
| $\overline{G}$ | gust response factor for primary framing systems of flexible buildings and structures |
| $G_h$ | gust response factor for primary framing systems evaluated at height $z=h$ |
| $G_z$ | gust response factor for components and cladding evaluated at height $z$ above ground |
| $h$ | mean roof height or height to top of parapet whichever is greater of a building or structure, except that eaves height may be used for roof slope of less than 10 degrees, metres. |
| $J$ | pressure profile factor as a function of ratio $\gamma$ |
| $L$ | horizontal dimension of a building or structure measured parallel to wind direction, metres |
| $M$ | larger dimension of a sign, metres |
| $N$ | smaller dimension of a sign, metres |
| $p$ | design pressure to be used in determination of wind loads for buildings, kN/m² |
| $p_h$ | design pressure evaluated at height $z=h$, kN/m² |
| $p_i$ | internal pressure, kN/m² |
| $p_z$ | design wind pressure evaluated at height $z$ above ground, kN/m² |
| $q$ | sustained wind pressure, kN/m² |
| $q_h$ | sustained wind pressure evaluated at height $z=h$, kN/m² |
| $q_z$ | sustained wind pressure evaluated at height $z$ above ground, in kN/m² |
| $r$ | rise-to-span ratio for arched roofs |
| $s$ | surface friction factor given in Table 6.2.12 |
| $S$ | structure size factor given in Fig 6.2.4 |
| $T_I$ | turbulence intensity factor evaluated at two-thirds of the mean roof height or parapet height of the structure (see Eq 2.4.11) |
| $V$ | basic wind speed, km/h |
| $X$ | distance to centre of pressure from windward edge, metres |
| $Y$ | response factor as a function of the ratio $\gamma$ and the ratio $c/h$ given in Fig 6.2.3 |
| $z$ | height above ground level, metres |
| $z_g$ | gradient height given in Table 6.2.12, metres |
| $\alpha$ | power-law coefficient given in Table 6.2.12 |
| $\beta$ | structural damping coefficient (fraction of critical damping) |
| $\gamma$ | ratio obtained from Table 6.2.12 |
| $\varepsilon$ | ratio of solid area to gross area for open sign face of a trussed tower, or lattice structure |
| $\theta$ | angle of the plane of roof from horizontal, degrees |
| $v$ | height-to-width ratio for sign or hoarding |
| $\phi$ | angle between wind direction and chord of tower guy, degrees. |
### 2.4.4 Terrain Exposure
A terrain exposure category that adequately reflects the surface roughness characteristics of the ground shall be determined for the building site, taking into account the variations in ground roughness arising from existing natural topography, vegetation and manmade constructions.
#### 2.4.4.1 Exposure Category
The terrain exposure in which a building or structure is to be sited shall be assessed as being one of the following categories:
a) **Exposure A:** Urban and sub-urban areas, industrial areas, wooded areas, hilly or other terrain covering at least 20 per cent of the area with obstructions of 6 metres or more in height and extending from the site at least 500 metres or 10 times the height of the structure, whichever is greater.
b) **Exposure B:** Open terrain with scattered obstructions having heights generally less than 10 m extending 800 m or more from the site in any full quadrant. This category includes air fields, open park lands, sparsely built-up outskirts of towns, flat open country and grasslands.
c) **Exposure C:** Flat and unobstructed open terrain, coastal areas and riversides facing large bodies of water, over 1.5 km or more in width. Exposure C extends inland from the shoreline 400 m or 10 times the height of structure, whichever is greater.
#### 2.4.4.2 Selection of Exposure Category for Primary Framing System
Design wind load for primary framing systems for all buildings and structures shall be determined based on the terrain exposure categories defined in Sec 2.4.4.1.
#### 2.4.4.3 Selection of Exposure Category for Components and Cladding
Design wind load on the components and cladding of all buildings and structures shall be determined on the basis of the exposure category defined in Sec 2.4.4.1, except that Exposure B shall be assumed for buildings or structures having $h \leq 20$ m and sited in a terrain with Exposure A.
### 2.4.5 Basic Wind Speed
#### 2.4.5.1 Basic Wind Speed Map
The Basic Wind Speed Map as shown in Fig 6.2.1 is the map showing the basic wind speeds in km/h for any location in Bangladesh, having isotachs representing the fastest-mile wind speeds at 10 metres above the ground with terrain Exposure B for a 50-year recurrence interval. The minimum value of the basic wind speed set in the map is 130 km/h. Basic wind speeds for selected locations are also provided in Table 6.2.8.
#### 2.4.5.2 Selection of Basic Wind Speed
Value of the basic wind speed required for any specific location where a building or structure is sited, shall be obtained as follows:
i) When the location is listed in Table 6.2.8, value of the basic wind speed shall be taken from that table.
ii) If the location lies within any wind region (shown shaded in the map of Fig 6.2.1), the value marked for that wind region shall be used.
iii) For a location lying on any isotach in the map, the value of that isotach shall be taken.
iv) For a location lying outside the positions (i) through (iii) above, linear interpolation shall be made between the adjacent isotachs to obtain the basic wind speed.
For areas where local records or terrain conditions indicate higher values of basic wind speeds (substantiated by site-specific analysis) than those reflected in Fig 6.2.1 and Table 6.2.8, the site-specific values shall be adopted as the minimum basic wind speeds.
### 2.4.6 Determination of Design Wind Loads
#### 2.4.6.1 Basis of Wind Load Calculation
The minimum design wind load on buildings, structures and components thereof shall be calculated, within the scope and limitations given in Sec 2.4.1 taking into account the following effects which shall be determined in accordance with the provisions of this section:
a) equivalent static pressure or suction on building surfaces arising due to the sustained or mean wind velocity, i.e. the fastest-mile wind speed,
b) variation of the mean wind velocity, and hence the pressure, along the height above the ground,
c) terrain exposure of the building site,
d) configuration and dynamic response characteristics of the building or structure,
e) occupancy importance of the building,
f) magnification of the mean wind pressure due to the effect of the fluctuating component of wind speed, i.e. gusts, and
g) additional load amplification resulting from the dynamic wind-structure interaction effects due to gusts on slender buildings and structures.
#### 2.4.6.2 Sustained Wind Pressure
The sustained wind pressure, $q_z$ on a building surface at any height z above ground shall be calculated from the following relation:
$$
q_z = C_c C_I C_z V_b^2 \tag{2.4.1}
$$
where, $q_z$ = sustained wind pressure at height z, kN/m²
$C_I$ = structure importance coefficient as given in Table 6.2.9
$C_c$ = velocity-to-pressure conversion coefficient = $47.2 \times 10^{-6}$
$C_z$ = combined height and exposure coefficient as given in Table 6.2.10
$V_b$ = basic wind speed in km/h obtained from Sec 2.4.5
If a structure is located within a local topographic zone, $q_z$ shall be modified in accordance with Sec 2.4.6.8.
**Table 6.2.8: Basic Wind Speeds for Selected Locations in Bangladesh**
| Location | Basic Wind Speed (km/h) | Location | Basic Wind Speed (km/h) |
| ---------------- | ----------------------- | ------------------- | ----------------------- |
| Angarpota | 150 | Lalmonirhat | 204 |
| Bagerhat | 252 | Madaripur | 220 |
| Bandarban | 200 | Magura | 208 |
| Barguna | 260 | Manikganj | 185 |
| Barisal | 256 | Meherpur | 185 |
| Bhola | 225 | Moheshkhali | 260 |
| Bogra | 198 | Moulvibazar | 168 |
| Brahmanbaria | 180 | Munshiganj | 184 |
| Chandpur | 160 | Mymensingh | 217 |
| Chapai Nawabganj | 130 | Naogaon | 175 |
| Chittagong | 260 | Narail | 222 |
| Chuadanga | 198 | Narayanganj | 195 |
| Comilla | 196 | Narsinghdi | 190 |
| Cox's Bazar | 260 | Natore | 198 |
| Dahagram | 150 | Netrokona | 210 |
| Dhaka | 210 | Nilphamari | 140 |
| Dinajpur | 130 | Noakhali | 184 |
| Faridpur | 202 | Pabna | 202 |
| Feni | 205 | Panchagarh | 130 |
| Gaibandha | 210 | Patuakhali | 260 |
| Gazipur | 215 | Pirojpur | 260 |
| Gopalganj | 242 | Rajbari | 188 |
| Habiganj | 172 | Rajshahi | 155 |
| Hatiya | 260 | Rangamati | 180 |
| Ishurdi | 225 | Rangpur | 209 |
| Joypurhat | 180 | Satkhira | 183 |
| Jamalpur | 180 | Shariatpur | 198 |
| Jessore | 205 | Sherpur | 200 |
| Jhalakati | 260 | Sirajganj | 160 |
| Jhenaidah | 208 | Srimangal | 160 |
| Khagrachhari | 180 | St. Martin's Island | 260 |
| Khulna | 238 | Sunamganj | 195 |
| Kutubdia | 260 | Sylhet | 195 |
| Kishoreganj | 207 | Sandwip | 260 |
| Kurigram | 210 | Tangail | 160 |
| Kushtia | 215 | Teknaf | 260 |
| Lakshmipur | 162 | Thakurgaon | 130 |
**Table 6.2.9: Structure Importance Coefficients, $C_I$ for Wind Loads**
| Structure Importance Category (see Table 6.1.1 for Occupancy) | Structure Importance Coefficient, $C_I$ |
| ------------------------------------------------------------- | --------------------------------------- |
| I Essential facilities | 1.25 |
| II Hazardous facilities | 1.25 |
| III Special occupancy structures | 1.00 |
| IV Standard occupancy structures | 1.00 |
| V Low-risk structures | 0.80 |
**Table 6.2.10: Combined Height and Exposure Coefficient, $C_z$**
| Height above ground level, z (metres) | Exposure A | Exposure B | Exposure C |
| ------------------------------------- | ---------- | ---------- | ---------- |
| 0-4.5 | 0.368 | 0.801 | 1.196 |
| 6.0 | 0.415 | 0.866 | 1.263 |
| 9.0 | 0.497 | 0.972 | 1.370 |
| 12.0 | 0.565 | 1.055 | 1.451 |
| 15.0 | 0.624 | 1.125 | 1.517 |
| 18.0 | 0.677 | 1.185 | 1.573 |
| 21.0 | 0.725 | 1.238 | 1.623 |
| 24.0 | 0.769 | 1.286 | 1.667 |
| 27.0 | 0.810 | 1.330 | 1.706 |
| 30.0 | 0.849 | 1.371 | 1.743 |
| 35.0 | 0.909 | 1.433 | 1.797 |
| 40.0 | 0.965 | 1.488 | 1.846 |
| 45.0 | 1.017 | 1.539 | 1.890 |
| 50.0 | 1.065 | 1.586 | 1.930 |
| 60.0 | 1.155 | 1.671 | 2.002 |
| 70.0 | 1.237 | 1.746 | 2.065 |
| 80.0 | 1.313 | 1.814 | 2.120 |
| 90.0 | 1.383 | 1.876 | 2.171 |
| 100.0 | 1.450 | 1.934 | 2.217 |
| 110.0 | 1.513 | 1.987 | 2.260 |
| 120.0 | 1.572 | 2.037 | 2.299 |
| 130.0 | 1.629 | 2.084 | 2.337 |
| 140.0 | 1.684 | 2.129 | 2.371 |
| 150.0 | 1.736 | 2.171 | 2.404 |
| 160.0 | 1.787 | 2.212 | 2.436 |
| 170.0 | 1.835 | 2.250 | 2.465 |
| 180.0 | 1.883 | 2.287 | 2.494 |
| 190.0 | 1.928 | 2.323 | 2.521 |
| 200.0 | 1.973 | 2.357 | 2.547 |
| 220.0 | 2.058 | 2.422 | 2.596 |
| 240.0 | 2.139 | 2.483 | 2.641 |
| 260.0 | 2.217 | 2.541 | 2.684 |
| 280.0 | 2.910 | 2.595 | 2.724 |
| 300.0 | 2.362 | 2.647 | 2.762 |
*Note (1): Linear interpolation is acceptable for intermediate values of z.*
![Fig 6.2.1: Basic Wind Speed Map of Bangladesh]()
*Fig 6.2.1: Basic Wind Speed Map (wind speeds in km/h)*
#### 2.4.6.3 Design Wind Pressure
The design wind pressure, $p_z$ for a structure or an element of a structure at any height, z above mean ground level shall be determined from the relation:
$$
p_z = C_G C_p q_z \tag{2.4.2}
$$
where, $p_z$ = design wind pressure at height z, kN/m²
$C_G$ = gust coefficient which shall be $G_h$, $G_z$, or $G_f$ as set forth in Sec 2.4.6.6
$C_p$ = pressure coefficient for structures or components as set forth in Sec 2.4.6.7
$q_z$ = sustained wind pressure obtained from Eq (2.4.1).
#### 2.4.6.4 Design Wind Load for Buildings and Structures
Design wind load on the main wind force resisting systems of buildings and structures shall be determined by using one of the following two methods:
a) **Method 1 (Surface Area Method):** The surface area method shall be used for gabled rigid frames and single storey rigid frames and may be used for other framing systems. In this method the design wind pressures shall be assumed to act simultaneously normal to all exterior surfaces including roof of buildings or structures. The forces $F_1$, acting normal to the building surfaces or the roof, shall be calculated as follows:
i) For all framing systems:
$$
F_1 = \sum p A_z \tag{2.4.3}
$$
where, $F_1$ = wind force on primary framing systems acting normal to a surface, or roof, or a part thereof.
$p$ = design wind pressure on building surfaces, kN/m²
$= p_z$ for windward surfaces as used in Eq (2.4.2)
$= p_h$ for non-windward surfaces as used in Eq (2.4.2)
$A_z$ = area of the building surface or roof tributary to the framing system at height z upon which the design pressure p operates, in square metres.
ii) For gabled frames and single-storey rigid frames:
In order to obtain the most critical loading condition, gabled frames and other single-storey rigid frames shall be investigated for both the force $F_1$ obtained from Eq (2.4.3) and that given by the relation:
$$
F_1 = \sum (p - p_i)A_z \tag{2.4.4}
$$
where, $p_i$ = internal pressure = $C'_{pi} \, q_h$
$C'_{pi}$ = internal peak pressure coefficient as given in Sec 2.4.6.7, and
$q_h$ = sustained wind pressure evaluated at mean roof height, given by Eq (2.4.1).
The resultant force of the complete framing system of the building shall be taken to be the summation of forces $F_1$ due to the effects of the pressures on all surfaces of the building. For the maximum force on the building, forces along all critical directions shall be investigated.
b) **Method 2 (Projected Area Method):** This method may be used for any building or structure as a whole other than those specified in a(ii) above. In the projected area method, the horizontal pressure shall be assumed to act upon the full vertical projected area of the structure and the vertical pressure shall be assumed to act simultaneously upon the full horizontal projected area, except where the pressure coefficients are given for the surface area, e.g. Table 6.2.17. According to Method 2, the total wind force on the primary framing system of a building or a structure shall be calculated using the formula:
$$
F_2 = \sum p_z \overline{A}_z \tag{2.4.5}
$$
where, $F_2$ = total wind force on the framed system of the building in a specified direction, kN
$p_z$ = design wind pressure, in kN/m², for use with the overall pressure coefficient $C_p$ for the cross-sectional shapes provided in Tables 6.2.15 to 6.2.21
$\overline{A}_z$ = projected frontal area normal to wind tributary to the framing system at height z, in square metres.
In the projected area method, the overall pressure coefficients $C_p$ provided in Tables 6.2.15 to 6.2.21 for various cross-sectional shapes, shall be used for the total height of the building or the structure having a particular cross-sectional shape. In order to determine the most critical loads, the total wind force $F_2$ shall be calculated for each wind direction for which the overall pressure coefficient $C_p$ is provided.
#### 2.4.6.5 Design Wind Loads for Components and Cladding
Design wind load on individual structural components such as roofs, walls, and individual cladding units and their immediate supporting members and fixings etc., of enclosed buildings and structures shall be determined in accordance with the following relation:
$$
F' = \sum (C_{pe} \, q - C_{pi} \, q_i) A_z \tag{2.4.6}
$$
where, $F'$ = total wind force on a building component perpendicular to the surface, kN
$C_{pe}$ = external peak pressure coefficient for components, see Fig 6.2.7 and 6.2.8 for rectangular building
$C_{pi}$ = internal peak pressure coefficient as given in Table 6.2.14
$q$ = sustained wind pressure acting on external surfaces of a building
$q_i$ = wind pressure developed at the interior of the building.
The pressures $q$ and $q_i$ shall be determined as follows:
For $h \leq 18$ m: $q = q_h$ and $q_i = q_h$
For $h > 18$ m: $q = q_z$ for (+ve) values of $C_{pe}$, and
$q = q_h$ for (-ve) values of $C_{pe}$
$q_i = q_h$ for all values of $C_{pe}$.
If the peak pressure coefficients $C_{pe}$ and $C_{pi}$ are not provided in Fig 6.2.7 and 6.2.8 and in Table 6.2.14, the following equation may be used for determining the wind forces on structural components:
$$
F' = \pm 1.25 \, p_z A_z \tag{2.4.7}
$$
where, $p_z$ = design wind pressure for components as given in Eq (2.4.2), kN/m²
$A_z$ = projected area of the component normal to wind at level, z above ground, in square metres.
#### 2.4.6.6 Wind Gust Effects
Wind gusts cause additional loading effects due to turbulence over the sustained wind speed. For slender buildings and structures, this additional loading gets further amplified due to dynamic wind structure interaction effects. A slender or wind-sensitive building shall be one having (i) a height exceeding five times the least horizontal dimension, or (ii) a fundamental natural frequency less than 1.0 Hz. Gust coefficient, $C_G$ as included in Eq (2.4.2) shall account for such additional gust loading effects on non-slender and slender buildings and shall be set equal to the Gust Response Factors, $G_h$, $G_z$ or $\overline{G}$ as set forth below:
a) **Gust Response Factor, $G_h$ for Non-slender Buildings and Structures:** For the main wind force resisting systems of non-slender buildings and structures, the value of the gust response factor, $G_h$ shall be determined from Table 6.2.11 evaluated at height h above mean ground level of the building or structure. Height h shall be defined as the mean roof level or the top of the parapet, whichever is greater.
b) **Gust Response Factor, $G_z$ for Building Components:** For components and cladding of all buildings and structures, the value of the gust response factor $G_z$ shall be determined from Table 6.2.11 evaluated at the height above the ground, z at which the component or cladding under consideration is located on the structure.
**Table 6.2.11: Gust Response Factors, $G_h$ and $G_z$**
| Height above ground level (metres) | Exposure A | Exposure B | Exposure C |
| ---------------------------------- | ---------- | ---------- | ---------- |
| 0-4.5 | 1.654 | 1.321 | 1.154 |
| 6.0 | 1.592 | 1.294 | 1.140 |
| 9.0 | 1.511 | 1.258 | 1.121 |
| 12.0 | 1.457 | 1.233 | 1.107 |
| 15.0 | 1.418 | 1.215 | 1.097 |
| 18.0 | 1.388 | 1.201 | 1.089 |
| 21.0 | 1.363 | 1.189 | 1.082 |
| 24.0 | 1.342 | 1.178 | 1.077 |
| 27.0 | 1.324 | 1.170 | 1.072 |
| 30.0 | 1.309 | 1.162 | 1.067 |
| 35.0 | 1.287 | 1.151 | 1.061 |
| 40.0 | 1.268 | 1.141 | 1.055 |
| 45.0 | 1.252 | 1.133 | 1.051 |
| 50.0 | 1.238 | 1.126 | 1.046 |
| 60.0 | 1.215 | 1.114 | 1.039 |
| 70.0 | 1.196 | 1.103 | 1.033 |
| 80.0 | 1.180 | 1.095 | 1.028 |
| 90.0 | 1.166 | 1.087 | 1.024 |
| 100.0 | 1.154 | 1.081 | 1.020 |
| 110.0 | 1.114 | 1.075 | 1.016 |
| 120.0 | 1.134 | 1.070 | 1.013 |
| 130.0 | 1.126 | 1.065 | 1.010 |
| 140.0 | 1.118 | 1.061 | 1.008 |
| 150.0 | 1.111 | 1.057 | 1.005 |
| 160.0 | 1.104 | 1.053 | 1.003 |
| 170.0 | 1.098 | 1.049 | 1.001 |
| 180.0 | 1.092 | 1.046 | 1.000 |
| 190.0 | 1.087 | 1.043 | 1.000 |
| 200.0 | 1.082 | 1.040 | 1.000 |
| 220.0 | 1.073 | 1.035 | 1.000 |
| 240.0 | 1.065 | 1.030 | 1.000 |
| 260.0 | 1.058 | 1.026 | 1.000 |
| 280.0 | 1.051 | 1.022 | 1.000 |
| 300.0 | 1.045 | 1.018 | 1.000 |
*Note (1): For main wind-force resisting systems, use building or structure height h for z.*
*Note (2): Linear interpolation is acceptable for intermediate values of z.*
c) **Gust Response Factor, $\overline{G}$ for Slender Buildings and Structures:** Gust response factor, $\overline{G}$ for the primary framing systems of slender buildings and structures shall be calculated by a rational analysis incorporating the dynamic properties of the primary framing system as given by the following relations.
$$
\overline{G} = 0.65 + \sqrt{\left( \frac{P}{\beta} + \frac{11.0 T_I^2 S}{1+kc} \right)} \tag{2.4.8}
$$
where,
$$
P = \bar{f} J Y \tag{2.4.9}
$$
$$
\bar{f} = \frac{55.44 fh}{sV_b} \tag{2.4.10}
$$
$$
T_I = \frac{2.35\sqrt{D_o}}{(h/13.72)^\alpha} \tag{2.4.11}
$$
$f$ = fundamental natural frequency of the building or structure, Hz
$\beta$ = structural damping coefficient (fraction of critical damping)
$h$ = mean roof height or height to parapet, metre
$c$ = average horizontal dimension of the building or structure normal to wind, metre
$V_b$ = basic wind speed, km/h
$k$ = 0.00656 for building or structure
$\phantom{k}$ = 0.00328 for open framework (lattice) structure
$J$ = pressure profile factor given in Fig 6.2.2
$Y$ = resonance factor given in Fig 6.2.3
$S$ = structure size factor provided in Fig 6.2.4
Other parameters of Eq (2.4.8) through (2.4.11) are defined in Sec 2.4.2. Values of the parameters $\alpha$, $D_o$, $s$ and $\gamma$ shall be those given in Table 6.2.12.
The gust response factor $\overline{G}$ as determined by this provision shall account for the load magnification effect caused by the wind gusts in resonance with along-wind oscillations of the structure, but shall not provide allowances for any cross-wind response such as that due to vortex shedding, galloping, flutter and ovalling, nor for any torsional loading effect resulting from such response. Cases where cross-wind or torsional loading is possible, specialist advice shall be sought for further analysis, or wind tunnel tests specified in Sec 1.5.3.5 shall be made for determining such effects.
![Fig 6.2.2: Pressure Profile Factor, J, as a Function of gamma]()
*Fig 6.2.2: Pressure Profile Factor, J, as a Function of $\gamma$*
![Fig 6.2.3: Resonance Factor, Y, as a Function of gamma and ratio c/h]()
*Fig 6.2.3: Resonance Factor, Y, as a Function of $\gamma$ and Ratio c/h*
![Fig 6.2.4: Structure Size Factor, S]()
*Fig 6.2.4: Structure Size Factor, S*
**Table 6.2.12: Building Exposure Parameters**
| Building Exposure | $\alpha$ | $D_o$ | $s$ | $\gamma$ |
| ----------------- | -------- | ----- | ---- | -------- |
| A | 0.222 | 0.010 | 1.33 | 1.0/h |
| B | 0.143 | 0.005 | 1.00 | 0.07/h |
| C | 0.100 | 0.003 | 0.85 | 0.0061/h |
#### 2.4.6.7 Pressure Coefficients for Buildings, Structures and Components
The pressure coefficients $C_p$ to be used in Eq (2.4.2) for the determination of design wind pressure shall be equal to the values described below:
a) $C_{pe}$: external pressure coefficient as given in Fig 6.2.5 and Fig 6.2.6 and in Table 6.2.13 for external surfaces of buildings or structures. This coefficient shall be used with Method 1 given in Sec 2.4.6.4a(i).
b) $C'_{pi}$: internal peak pressure coefficients as given in Table 6.2.14 for internal surfaces of buildings. These coefficients shall be used along with the coefficients $C'_{pe}$ for design wind load on components, or with $C_{pe}$ for design wind load on buildings as per provisions of Sec 2.4.6.4a(ii).
c) $C'_{pe}$: external peak pressure coefficient as given in Fig 6.2.7 and 6.2.8 to be applied on external surfaces of buildings to obtain design wind load on individual components and cladding in accordance with Sec 2.4.6.5.
d) $\overline{C}_p$: overall pressure coefficient as given in Tables 6.2.15 through 6.2.21 for various cross-sectional shapes to be used with the projected area of buildings or structures when Method 2 in Sec 2.4.6.4(b) is used.
If pressure coefficients $C_{pe}$, $C'_{pi}$, $C'_{pe}$ or $\overline{C}_p$ are not provided herein for certain buildings, structures or components, reliable references shall be followed or specialist advice shall be sought.
![Fig 6.2.5: External Pressure Coefficients, Cpe for Primary Framing Systems of Rectangular Buildings]()
*Fig 6.2.5: External Pressure Coefficients, $C_{pe}$ for Primary Framing Systems of Rectangular Buildings. Notation: B = horizontal dimension of building measured normal to wind direction, $C_G$ = gust response coefficient, h = mean roof height (eave height may be used for $\theta \leq 10°$), L = horizontal dimension of building measured parallel to wind direction, $p_h$ = design wind pressure, $q_h, q_z$ = sustained wind pressure at respective heights, z = height above ground, $\theta$ = roof slope from horizontal. Windward wall: $p_z = C_G C_{pe} q_z$; Leeward wall: $p_h = C_G C_{pe} q_h$; Side wall: $p_z = C_G C_{pe} q_z$. These coefficients may be used when h/B ≤ 5.0; alternatively use Table 6.2.15 and Method 2, Sec 2.4.6.4(b). Notes: (1) These coefficients shall be used with Method 1, Sec 2.4.6.4(a). (2) Refer to Table 6.2.13 for arched roofs. (3) For flexible buildings and structures, use appropriate $\overline{G}$ as determined by Sec 2.4.6.6(c). (4) Plus and minus signs signify pressures acting toward and away from the surfaces, respectively. (5) Linear interpolation may be made for values of $\theta$, h/L, and L/B ratios other than listed.*
![Fig 6.2.6: External Pressure Coefficients, Cpe for Multi-span Buildings]()
*Fig 6.2.6: External Pressure Coefficients, $C_{pe}$ for Multi-span Buildings (Pitched Roof, North-Light Roof, Saw-Tooth Roof). Notes: (1) For components and cladding use Fig 6.2.6 for $\alpha = 90°$ and $270°$, $C_{pe}$ = (values given in Fig 6.2.5) − \[0.05(N−1)], where N = number of spans; N = 4 if N > 4. (2) When two values of $C_{pe}$ are listed, roofs shall be designed for both values.*
**Table 6.2.13: External Pressure Coefficients, $C_{pe}$ for Arched Roofs**
| Condition | Rise-to-span Ratio, r | $C_{pe}$ Windward Quarter | $C_{pe}$ Centre half | $C_{pe}$ Leeward Quarter |
| --------------------------------- | --------------------- | ------------------------- | -------------------- | ------------------------ |
| Roofs on elevated structures | $0 < r \leq 0.2$ | −0.9 | −0.7 − r | −0.5 |
| | $0.2 < r \leq 0.3^*$ | 1.5r − 0.3 | −0.7 − r | −0.5 |
| | $0.3 < r \leq 0.6$ | 2.75r − 0.7 | −0.7 − r | −0.5 |
| Roofs springing from ground level | $0 < r \leq 0.6$ | 1.4r | −0.7 − r | −0.5 |
\* When the rise-to-span ratio is $0.2 \leq r \leq 0.3$ alternate coefficients given by $(6r - 2.1)$ shall also be used for the windward quarter.
*Notes: (1) Values listed are for the determination of average loads on primary framing system. (2) Plus and minus signs signify pressures acting toward and away from the surfaces, respectively. (3) For components and cladding: a) At roof perimeter, use the external pressure coefficients in Fig 6.2.7 with $\theta$ based on spring-line slope and $q_h$ based on Exposure B. b) For remaining roof area, use external pressure coefficients of this table multiplied by 1.2 and $q_h$ based on Exposure B.*
**Table 6.2.14: Internal Peak Pressure Coefficients for Buildings, $C'_{pi}$**
| Condition | $C'_{pi}$ |
| ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------- |
| Percentage of total wall area occupied by openings in one wall exceeds that of all other walls by 10% or more and openings in all other walls do not exceed 20% of respective wall area. | + 0.75 and − 0.25 |
| All other cases | ± 0.25 |
*Notes: (1) Values are to be used with $q_z$ or $q_h$ as specified in Sec 2.4.6.4 a(ii) and 2.4.6.5. (2) Plus and minus signs signify pressures acting toward and away from the surfaces, respectively. (3) Appropriate positive and negative values of $C'_{pi}$ shall be considered when determining the controlling load requirement. (4) Percentage of openings is based on gross area of wall.*
![Fig 6.2.7: External Peak Pressure Coefficients Cpe' for Loads on Building Components and Cladding for Buildings with Mean Roof Height h of 18 metres or Less]()
*Fig 6.2.7: External Peak Pressure Coefficients $C'_{pe}$ for Loads on Building Components and Cladding for Buildings with Mean Roof Height, h of 18 metres or Less. Notes: (1) Vertical scale denotes $C'_{pe}$ to be used with $q_h$ based on Exposure B. (2) The horizontal scale denotes tributary area in square metres. (3) External pressure coefficients for walls may be reduced by 10% when $\theta \leq 10$ degrees. (4) Plus and minus signs signify pressures acting toward and away from the surfaces, respectively. (5) Each component shall be designed for maximum positive and negative pressures. (6) Roof overhangs shall have $C'_{pe}$ given in Fig (b) to be applied at the top surface plus a $C'_{pe} = +0.8$ applied at the bottom surface.*
![Fig 6.2.8: External Peak Pressure Coefficients Cpe' for Loads on Building Components and Cladding for Buildings with Mean Roof Height h Greater Than 18 metres]()
*Fig 6.2.8: External Peak Pressure Coefficients $C'_{pe}$ for Loads on Building Components and Cladding for Buildings with Mean Roof Height, h Greater Than 18 metres. Notation: a = 5% of minimum width or 0.5h, whichever is smaller; h = mean roof height, metres; z = height above ground, metres. Notes: (1) Vertical scale denotes $C'_{pe}$ to be used with appropriate $q_z$ or $q_h$. (2) Horizontal scale denotes tributary area A in square metres. (3) Use $q_h$ with negative values of $C'_{pe}$. (4) Each component shall be designed for maximum positive and negative pressures. (5) If a parapet is provided around the roof perimeter, zones (3) and (4) may be treated as zone (2). (6) For roofs with a slope of more than 10 degrees, use $C'_{pe}$ from Fig 6.2.7 and $q_h$ based on Exposure B. (7) Plus and minus signs signify pressures acting toward and away from the surfaces, respectively. (8) Roof overhangs shall have $C'_{pe}$ given in Fig (b) to be applied at the top surface plus a $C'_{pe} = +0.8$ applied at the bottom surface. (9) For parapet use $C'_{pe} = \pm 1.3$.*
**Table 6.2.15: Overall Pressure Coefficients, $\overline{C}_p$ for Rectangular Buildings with Flat Roofs**
| h/B | L/B 0.1 | L/B 0.5 | L/B 0.65 | L/B 1.0 | L/B 2.0 | L/B ≥3.0 |
| ----- | ------- | ------- | -------- | ------- | ------- | -------- |
| ≤0.5 | 1.40 | 1.45 | 1.55 | 1.40 | 1.15 | 1.10 |
| 10.0 | 1.55 | 1.85 | 2.00 | 1.70 | 1.30 | 1.15 |
| 20.0 | 1.80 | 2.25 | 2.55 | 2.00 | 1.40 | 1.20 |
| ≥40.0 | 1.95 | 2.50 | 2.80 | 2.20 | 1.60 | 1.25 |
*Note: (1) These coefficients are to be used with Method-2 given in Sec 2.4.6.6a(ii). Use $\overline{C}_p = \pm 0.7$ for roof in all cases. (2) Linear interpolation may be made for intermediate values of h/B and L/B.*
**Table 6.2.16: Overall Pressure Coefficient, $\overline{C}_p$ for Buildings and Structures such as Chimneys, Tanks, etc.**
| Shape | Type of surface | $\overline{C}_p$ for h/D = 1 | $\overline{C}_p$ for h/D = 7 | $\overline{C}_p$ for h/D = 25 |
| ---------------------------------------------- | -------------------------------- | ---------------------------- | ---------------------------- | ----------------------------- |
| Square (wind normal to a face) | All | 1.3 | 1.4 | 2.0 |
| Square (wind along diagonal) | All | 1.0 | 1.1 | 1.5 |
| Hexagonal or octagonal ($D\sqrt{q_z} > 0.167$) | All | 1.0 | 1.2 | 1.4 |
| Round ($D\sqrt{q_z} > 0.167$) | Moderately smooth | 0.5 | 0.6 | 0.7 |
| Round ($D\sqrt{q_z} > 0.167$) | Rough ($D'/D \approx 0.02$) | 0.7 | 0.8 | 0.9 |
| Round ($D\sqrt{q_z} > 0.167$) | Very rough ($D'/D \approx 0.08$) | 0.8 | 1.0 | 1.2 |
| Round ($D\sqrt{q_z} \leq 0.167$) | All | 0.7 | 0.8 | 1.2 |
*Notes: 1) The design wind force shall be calculated based on the area of the structure projected on a plane normal to the wind direction. The force shall be assumed to act parallel to the wind direction. 2) Linear interpolation may be used for h/D values other than those shown. 3) Notation: D = diameter or least horizontal dimension, metres. D' = depth of protruding elements such as ribs and spoilers, metres. h = height of structure, metres.*
**Table 6.2.17: Overall Pressure Coefficients $\overline{C}_p$ for Monoslope Roofs Over Unenclosed Buildings and Structures**
| $\theta$ (degrees) | L/B = 5 | L/B = 3 | L/B = 2 | L/B = 1 | L/B = 1/2 | L/B = 1/3 | L/B = 1/5 |
| ------------------ | ------- | ------- | ------- | ------- | --------- | --------- | --------- |
| 10 | 0.2 | 0.25 | 0.3 | 0.45 | 0.55 | 0.7 | 0.75 |
| 15 | 0.35 | 0.45 | 0.5 | 0.7 | 0.85 | 0.9 | 0.85 |
| 20 | 0.5 | 0.6 | 0.75 | 0.9 | 1.0 | 0.95 | 0.9 |
| 25 | 0.7 | 0.8 | 0.95 | 1.15 | 1.1 | 1.05 | 0.95 |
| 30 | 0.9 | 1.0 | 1.2 | 1.3 | 1.2 | 1.1 | 1.0 |
Location of centre of pressure, X/L:
| $\theta$ (degrees) | L/B = 2 to 5 | L/B = 1 | L/B = 1/5 to 1/2 |
| ------------------ | ------------ | ------- | ---------------- |
| 10 to 20 | 0.35 | 0.3 | 0.3 |
| 25 | 0.35 | 0.35 | 0.4 |
| 30 | 0.35 | 0.4 | 0.45 |
*Note: 1) Wind forces act normal to the surface and shall be directed inward or outward. 2) Wind shall be assumed to deviate by ± 10 degrees from horizontal. 3) Notation: B = dimension of roof measured normal to wind direction, metres. L = dimension of roof measured parallel to wind direction, metres. X = distance to centre of pressure from windward edge of roof, metres. $\theta$ = angle of plane of roof from horizontal, degrees.*
**Table 6.2.18: Overall Pressure Coefficients, $\overline{C}_p$ for Solid Signs**
| At Ground Level v | At Ground Level $\overline{C}_p$ | Above Ground Level M/N | Above Ground Level $\overline{C}_p$ |
| ----------------- | -------------------------------- | ---------------------- | ----------------------------------- |
| ≤3 | 1.2 | ≤6 | 1.2 |
| 5 | 1.3 | 10 | 1.3 |
| 8 | 1.4 | 16 | 1.4 |
| 10 | 1.5 | 20 | 1.5 |
| 20 | 1.75 | 40 | 1.75 |
| 30 | 1.85 | 60 | 1.85 |
| ≥40 | 2.00 | ≥80 | 2.00 |
*Note: 1) Signs with openings comprising less than 30% of the gross area shall be considered as solid signs. 2) Signs for which the distance from the ground to the bottom edge is less than 0.25 times the vertical dimension shall be considered to be at ground level. 3) To allow for both normal and oblique wind directions, two cases shall be considered: a) Resultant force acts normal to sign at geometric centre, and b) Resultant force acts normal to sign at level of geometric centre and at a distance from windward edge of 0.3 times the horizontal dimension. 4) Notation: v = ratio of height to width, M = larger dimension of sign, metres, N = smaller dimension of sign, metres.*
**Table 6.2.19: Overall Pressure Coefficients $\overline{C}_p$ for Open Signs and Lattice Frameworks**
| $\varepsilon$ | Flat-sided Members | Round Members $D\sqrt{q_z} \leq 0.167$ | Round Members $D\sqrt{q_z} > 0.167$ |
| ------------- | ------------------ | -------------------------------------- | ----------------------------------- |
| \< 0.1 | 2.0 | 1.2 | 0.8 |
| 0.1 to 0.29 | 1.8 | 1.3 | 0.9 |
| 0.3 to 0.7 | 1.6 | 1.5 | 1.1 |
*Notes: 1) Signs with openings comprising 30% or more of the gross area are classified as open signs. 2) The calculation of the design wind forces shall be based on the area of all exposed members and elements projected on a plane normal to the wind direction. Forces shall be assumed to act parallel to the wind direction. 3) Notation: $\varepsilon$ = ratio of solid area to gross area, D = diameter of a typical round member, in metres.*
**Table 6.2.20: Overall Pressure Coefficients, $\overline{C}_p$ for Trussed Towers**
| $\varepsilon$ | Square Towers $\overline{C}_p$ | Triangular Towers $\overline{C}_p$ |
| ------------- | ------------------------------ | ---------------------------------- |
| \< 0.025 | 4.0 | 3.6 |
| 0.025 to 0.44 | 4.1 − 5.2$\varepsilon$ | 3.7 − 4.5$\varepsilon$ |
| 0.45 to 0.69 | 1.8 | 1.7 |
| 0.7 to 1.0 | 1.3 + 0.7$\varepsilon$ | 1.0 + $\varepsilon$ |
*Note: 1) Force coefficients are given for towers with structural angles or similar flat-sided members. 2) For towers with rounded members, the design wind force shall be determined using the values in the above table multiplied by the following factors: For $\varepsilon \leq 0.29$: factor = 0.67. For $0.3 \leq \varepsilon \leq 0.79$: factor = $0.67\varepsilon + 0.47$. For $0.8 \leq \varepsilon \leq 1.0$: factor = 1.0. 3) For triangular section towers, the design wind forces shall be assumed to act normal to a tower face. 4) For square section towers, the design wind forces shall be assumed to act normal to a tower face. To allow for the maximum horizontal wind load, which occurs when the wind is oblique to the faces, the wind load acting normal to a tower face shall be multiplied by the factor $1.0 + 0.75\varepsilon$ for $\varepsilon < 0.5$ and shall be assumed to act along a diagonal. 5) Wind forces on tower appurtenances, such as ladders, conduits, lights, elevators, and the like, shall be calculated using appropriate force coefficients for these elements. 6) For guyed towers, the cantilever portion of the tower shall be designed for 125% of the design force. 7) A reduction of 25% of the design force in any span between guys shall be made for determination of controlling moments and shears. 8) Notation: $\varepsilon$ = ratio of solid area to gross area of tower face. D = typical member diameter, in metres.*
**Table 6.2.21: Overall Pressure Coefficients, $\overline{C}_{p'D}$ and $\overline{C}_{p'L}$ for Tower Guys**
| $\phi$ (degrees) | $\overline{C}_{p'D}$ | $\overline{C}_{p'L}$ |
| ---------------- | -------------------- | -------------------- |
| 10 | 0.05 | 0.05 |
| 20 | 0.10 | 0.15 |
| 30 | 0.20 | 0.30 |
| 40 | 0.35 | 0.35 |
| 50 | 0.60 | 0.45 |
| 60 | 0.80 | 0.45 |
| 70 | 1.05 | 0.35 |
| 80 | 1.15 | 0.20 |
| 90 | 1.20 | 0.00 |
*Notes: 1) The force coefficients shall be used in conjunction with exposed area of the tower guy in square metre, calculated as chord length multiplied by guy diameter. 2) Notation: $\overline{C}_{p'D}$ = force coefficient for the component of force acting in direction of the wind. $\overline{C}_{p'L}$ = force coefficient for the component of force acting normal to direction of the wind and in the plane containing the angle $\phi$. $\phi$ = angle between wind direction and chord of the guy, in degrees.*
#### 2.4.6.8 Effect of Local Topography
If a structure or any portion thereof is located within a local topographic zone, such as regions around hills and ridges as shown in Fig 6.2.9, the sustained wind pressure obtained from Sec 2.4.6.2 shall be modified by multiplying by a local topographic coefficient, $C_t$. Value of the coefficient, $C_t$ shall be obtained from Fig 6.2.9.
![Fig 6.2.9: Local Topographic Coefficient, Ct for Hills and Ridges]()
*Fig 6.2.9: Local Topographic Coefficient, $C_t$ for Hills and Ridges.*
**Local Topographic Coefficient, $C_t$ at Crest**
| Upwind slope (tan $\phi$) | Coefficient, $C_t$ |
| ------------------------- | ------------------ |
| 0.05 | 1.19 |
| 0.1 | 1.39 |
| 0.2 | 1.85 |
| ≥ 0.3 | 2.37 |
**Legend:**
$\tan\phi$ = the upwind slope, $\dfrac{H}{2L_u}$
$\tan\phi_d$ = the average downwind slope, measured from the crest of a hill or ridge to the ground level at a distance of 5H.
$H$ = the height of the hill or ridge in metres
$L_u$ = the horizontal distance upwind from the crest to a level half the height below the crest in metres.
*Notes: (1) For intermediate values of upwind slope, linear interpolation is permitted. (2) $C_t = 1.0$ for a point at or outside the boundary of the local topographic zones as shown in the figure. For any point within the local topographic zone, value of the coefficient, $C_t$ shall be obtained by interpolation from the value at crest given in the table and the value of $C_t = 1$ at the boundary of the zone. The interpolation shall be linear with horizontal distance from the crest, and with height above the local ground level.*
## 2.5 Earthquake Loads
### 2.5.1 General
Minimum design earthquake forces for buildings, structures or components thereof shall be determined in accordance with the provisions of this section. For primary framing systems of buildings or structures, the design seismic lateral forces shall be calculated either by the Equivalent Static Force Method or by the Dynamic Response Method based on the criteria set forth in Sec 2.5.5.1. Overall design of buildings and structures to resist seismic ground motion and other forces shall comply with the applicable design requirements given in Chapter 1.
### 2.5.2 Definitions
The following definitions of terms shall be applicable only to the provisions of Sec 2.5:
**BASE:** The level at which the earthquake motions are considered to be imparted to the structures or the level at which the structure as a dynamic vibrator is supported.
**BASE SHEAR:** Total design lateral force or shear at the base of a structure.
**BEARING WALL SYSTEM:** A structural system without a complete vertical load carrying space frame, see Sec 1.3.2.
**BRACED FRAME:** An essentially vertical truss system of the concentric or eccentric type which is provided to resist lateral forces.
**BUILDING FRAME SYSTEM:** An essentially complete space frame which provides support for gravity loads, see Sec 1.3.2.
**DIAPHRAGM:** A horizontal or nearly horizontal system of structures acting to transmit lateral forces to the vertical resisting elements. The term "diaphragm" includes horizontal bracing systems.
**DUAL SYSTEM:** A combination of a Special or Intermediate Moment Resisting Frame and Shear Walls or Braced Frames designed in accordance with the criteria of Sec 1.3.2.
**ECCENTRIC BRACED FRAME (EBF):** A steel braced frame designed in conformance with Sec 1.8.
**ESSENTIAL FACILITIES:** Buildings and structures which are necessary to remain functional during an emergency or a post disaster period.
**FLEXIBLE DIAPHRAGM:** A floor or roof diaphragm shall be considered flexible, for purposes of this provision, when the maximum lateral deformation of the diaphragm is more than two times the average storey drift of the associated storey. This may be determined by comparing the computed midpoint in-plane deflection of the diaphragm under lateral load with the storey drift of adjoining vertical resisting elements under equivalent tributary lateral load.
**FLEXIBLE ELEMENT OR SYSTEM:** An element or system whose deformation under lateral load is significantly larger than adjoining parts of the system.
**FLEXIBLY SUPPORTED EQUIPMENT:** Non-rigid or flexibly supported equipment is a system having a fundamental period, including the equipment, greater than 0.06 second.
**HORIZONTAL BRACING SYSTEM:** A horizontal truss system that serves the same function as a floor or roof diaphragm.
**INTERMEDIATE MOMENT RESISTING FRAME (IMRF):** A concrete or steel frame designed in accordance with Sec 8.3 or 10.5.17 respectively.
**MOMENT RESISTING FRAME:** A frame in which members and joints are capable of resisting forces primarily by flexure.
**ORDINARY MOMENT RESISTING FRAME (OMRF):** A moment resisting frame not meeting special detailing requirements for ductile behaviour.
**PRIMARY FRAMING SYSTEM:** That part of the structural system assigned to resist lateral forces.
**RIGIDLY SUPPORTED EQUIPMENT:** A rigid or rigidly supported equipment is a system having a fundamental period less than or equal to 0.06 second.
**SHEAR WALL:** A wall designed to resist lateral forces parallel to the plane of the wall (sometimes referred to as a vertical diaphragm or a structural wall).
**SOFT STOREY:** Storey in which the lateral stiffness is less than 70 per cent of the stiffness of the storey above.
**SPACE FRAME:** A three-dimensional structural system without bearing walls composed of members interconnected so as to function as a complete self contained unit with or without the aid of horizontal diaphragms or floor bracing systems.
**SPECIAL MOMENT RESISTING FRAME (SMRF):** A moment resisting frame specially detailed to provide ductile behaviour complying with the seismic requirements provided in Chapters 8 and 10 for concrete and steel frames respectively.
**SPECIAL STRUCTURAL SYSTEM:** A structural system not listed in Table 6.2.24.
**STOREY:** The space between floor levels. Storey-x is the storey below level-x.
**STOREY SHEAR, $V_x$:** The summation of design lateral forces above the storey under consideration.
**STRENGTH:** The usable capacity of an element or a member to resist the load as prescribed in these provisions.
**STRUCTURE:** An assemblage of framing members designed to support gravity loads and resist lateral forces. Structures may be categorized as building and non-building structures as defined in Sec 1.2.2.
**TOWER:** A tall, slim vertical structure.
**VERTICAL LOAD-CARRYING FRAME:** A space frame designed to carry all vertical gravity loads.
**WEAK STOREY:** Storey in which the lateral strength is less than 80 per cent of that of the storey above.
### 2.5.3 Symbols and Notation
The following symbols and notation shall apply to the provisions of this section:
$A_c$ = the combined effective area, in square metres of the shear walls in the first storey of the structure.
$A_e$ = the effective horizontal cross-sectional area, in square metres of a shear wall in the first storey of the structure.
$A_x$ = the torsion amplification factor at level-x.
$C$ = numerical coefficient specified in Sec 2.5.6.1.
$C'$ = numerical coefficient specified in Sec 2.5.8 and given in Table 6.2.26.
$C_t$ = numerical coefficient given in Sec 2.5.6.2.
$D_e$ = the length in metres of a shear wall element in the first storey in the direction parallel to the applied forces.
$f_i$ = lateral force at level-i for use in Eq (2.5.5).
$F_i, F_n, F_x$ = lateral force applied to level-i, -n, or -x respectively.
$F'$ = lateral forces on an element or component or on equipment supports.
$F_t$ = that portion of the base shear V, considered concentrated at the top of the structure in addition to $F_n$.
$F'_x$ = force on floor- or roof-diaphragm.
$g$ = acceleration due to gravity.
$h_i, h_n, h_x$ = height in metres above the base to level i, -n or -x respectively.
$I$ = structure importance coefficient given in Table 6.2.23.
$I'$ = structure importance coefficient specified in Sec 2.5.8 for structural and non-structural components and equipment.
Level-i = the level of the structure referred to by the subscript i, e.g., i = 1 designates the first level above the base.
Level-n = the uppermost level in the main portion of the structure.
Level-x = the level under consideration e.g., x = 1 designates the first level above the base.
$R$ = response modification coefficient for structural systems given in Table 6.2.24.
$S$ = site coefficient for soil characteristics given in Table 6.2.25.
$T$ = fundamental period of vibration, in seconds, of the structure in the direction under consideration.
$V$ = the total design lateral force or shear at the base.
$V_x$ = the design storey shear in storey x.
$W$ = the total seismic dead load defined in Sec 2.5.5.2.
$W_i, W_x$ = that portion of W which is located at or assigned to level -i or -x respectively.
$w'_x$ = the weight of the diaphragm and the elements tributary thereto at level-x, including applicable portions of other loads defined in Sec 2.5.5.2.
$W'$ = the weight of an element or component.
$Z$ = seismic zone coefficient given in Table 6.2.22.
$\delta_i$ = horizontal displacement at level-i relative to the base due to applied lateral forces, in metre, for use in Eq (2.5.5).
### 2.5.4 Seismic Zoning
#### 2.5.4.1 Seismic Zoning Map
The seismic zoning map of Bangladesh is provided in Fig 6.2.10. Based on the severity of the probable intensity of seismic ground motion and damages, Bangladesh has been divided into three seismic zones, i.e. Zone 1, Zone 2 and Zone 3 as shown in Fig 6.2.10 with Zone 3 being the most severe.
#### 2.5.4.2 Selection of Seismic Zone and Zone Coefficient
Seismic zone for a building site shall be determined based on the location of the site on the Seismic Zoning Map provided in Fig 6.2.10. Each building or structure shall be assigned a Seismic Zone Coefficient, Z corresponding to the seismic zone of the site as set forth in Table 6.2.22.
### 2.5.5 Earthquake Forces for Primary Framing Systems
The design earthquake lateral forces on the primary framing systems of every building or structure shall be calculated based on the provisions set forth in this section. The design seismic forces shall be assumed to act nonconcurrently in the direction of each principal axis of the building or the structure, except otherwise required by the provisions of Sec 1.5.4 and 1.7.
#### 2.5.5.1 Selection of Lateral Force Method
Seismic lateral forces on primary framing systems shall be determined by using either the Equivalent Static Force Method provided in Sec 2.5.6, or the Dynamic Response Method given in Sec 2.5.7 complying with the restrictions given below:
a) The Equivalent Static Force Method of Sec 2.5.6 may be used for the following structures:
i) All structures, regular or irregular, in Seismic Zone 1 and in Structure Importance Category IV in Seismic Zone 2, except case b(iv) below.
ii) Regular structures under 75 metres in height with lateral force resistance provided by structural systems listed in Table 6.2.24, except case b(iv) below.
iii) Irregular structures not more than 20 metres in height.
iv) A tower like building or structure having a flexible upper portion supported on a rigid lower portion where:
1. both portions of the structure considered separately can be classified as regular structures,
2. the average storey stiffness of the lower portion is at least ten times the average storey stiffness of the upper portion, and
3. the period of the entire structure is not greater than 1.1 times the period of the upper portion considered as a separate structure fixed at the base.
b) The Dynamic Response Method as given in Sec 2.5.7 may be used for all classes of structure, but shall be used for structures of the following types.
i) Structures 75 metres or more in height, except as permitted by case a(i) above.
ii) Structures having a stiffness, weight or geometric vertical irregularity of Type I, II, or III as defined in Table 6.1.3, or structures having irregular features not described in either Table 6.1.3 or 6.1.4.
iii) Structures over 20 metres in height in Seismic Zone 3 not having the same structural system throughout their height except as permitted by Sec 1.6.4.
iv) Structures, regular or irregular, located on Soil Profile Type $S_4$ as given in Table 6.2.25, which have a period greater than 0.7 second. The analysis shall include the effects of the soils at the site and shall conform to Sec 2.5.7.1(c).
#### 2.5.5.2 Seismic Dead Load
Seismic dead load, W, is the total dead load of a building or a structure, including permanent partitions, and applicable portions of other loads listed below:
a) In storage and warehouse occupancies, a minimum of 25 per cent of the floor live load shall be applicable.
b) Where an allowance for partition load is included in the floor design in accordance with Sec 2.3.3.3, all such loads but not less than 0.6 kN/m² shall be applicable.
c) Total weight of permanent equipment shall be included.
![Fig 6.2.10: Seismic Zoning Map of Bangladesh]()
*Fig 6.2.10: Seismic Zoning Map of Bangladesh — Zone 1 (Z=0.075), Zone 2 (Z=0.15), Zone 3 (Z=0.25).*
### 2.5.6 Equivalent Static Force Method
This method may be used for calculation of seismic lateral forces for all structures specified in Sec 2.5.5.1(a).
#### 2.5.6.1 Design Base Shear
The total design base shear in a given direction shall be determined from the following relation:
$$
V = \frac{ZIC}{R} W \tag{2.5.1}
$$
where, $Z$ = Seismic zone coefficient given in Table 6.2.22
$I$ = Structure importance coefficient given in Table 6.2.23
$R$ = Response modification coefficient for structural systems given in Table 6.2.24
$W$ = The total seismic dead load defined in Sec 2.5.5.2
$C$ = Numerical coefficient given by the relation:
$$
C = \frac{1.25S}{T^{2/3}} \tag{2.5.2}
$$
$S$ = Site coefficient for soil characteristics as provided in Table 6.2.25
$T$ = Fundamental period of vibration in seconds, of the structure for the direction under consideration as determined by the provisions of Sec 2.5.6.2.
The value of C need not exceed 2.75 and this value may be used for any structure without regard to soil type or structure period. Except for those requirements where Code prescribed forces are scaled up by 0.375R, the minimum value of the ratio C/R shall be 0.075.
**Table 6.2.22: Seismic Zone Coefficients, Z**
| Seismic Zone (see Fig 6.2.10) | Zone Coefficient |
| ----------------------------- | ---------------- |
| 1 | 0.075 |
| 2 | 0.15 |
| 3 | 0.25 |
**Table 6.2.23: Structure Importance Coefficients I, I'**
| Structure Importance Category (see Table 6.1.1 for occupancy) | $I$ | $I'$ |
| ------------------------------------------------------------- | ---- | ---- |
| I Essential facilities | 1.25 | 1.50 |
| II Hazardous facilities | 1.25 | 1.50 |
| III Special occupancy structures | 1.00 | 1.00 |
| IV Standard occupancy structures | 1.00 | 1.00 |
| V Low-risk Structures | 1.00 | 1.00 |
#### 2.5.6.2 Structure Period
The value of the fundamental period, T of the structure shall be determined from one of the following methods:
a) **Method A:** For all buildings the value of T may be approximated by the following formula:
$$
T = C_t (h_n)^{3/4} \tag{2.5.3}
$$
where, $C_t$ = 0.083 for steel moment resisting frames
$\phantom{C_t} =$ 0.073 for reinforced concrete moment resisting frames, and eccentric braced steel frames
$\phantom{C_t} =$ 0.049 for all other structural systems
$h_n$ = Height in metres above the base to level n.
Alternatively, the value of $C_t$ for buildings with concrete or masonry shear walls may be taken as $0.031/\sqrt{A_c}$. The value of $A_c$ shall be obtained from the relation:
$$
A_c = \sum A_e \left[ 0.2 + (D_e/h_n)^2 \right] \tag{2.5.4}
$$
where, $A_c$ = The combined effective area, in square metres, of the shear walls in the first storey of the structure.
$A_e$ = The effective horizontal cross-sectional area, in square metres of a shear wall in the first storey of the structure.
$D_e$ = The length, in metre of a shear wall element in the first storey in the direction parallel to the applied forces.
The value of $D_e/h_n$ for use in Eq (2.5.4) shall not exceed 0.9.
**Table 6.2.24: Response Modification Coefficient for Structural Systems, R**
| Basic Structural System | Description of Lateral Force Resisting System | R |
| -------------------------------- | ------------------------------------------------------------- | -- |
| a. Bearing Wall System | 1. Light framed walls with shear panels | |
| | i) Plywood walls for structures, 3 storeys or less | 8 |
| | ii) All other light framed walls | 6 |
| | 2. Shear walls | |
| | i) Concrete | 6 |
| | ii) Masonry | 6 |
| | 3. Light steel framed bearing walls with tension only bracing | 4 |
| | 4. Braced frames where bracing carries gravity loads | |
| | i) Steel | 6 |
| | ii) Concrete (3) | 4 |
| | iii) Heavy timber | 4 |
| b. Building Frame System | 1. Steel eccentric braced frame (EBF) | 10 |
| | 2. Light framed walls with shear panels | |
| | i) Plywood walls for structures 3-storeys or less | 9 |
| | ii) All other light framed walls | 7 |
| | 3. Shear walls | |
| | i) Concrete | 8 |
| | ii) Masonry | 8 |
| | 4. Concentric braced frames (CBF) | |
| | i) Steel | 8 |
| | ii) Concrete (3) | 8 |
| | iii) Heavy timber | 8 |
| c. Moment Resisting Frame System | 1. Special moment resisting frames (SMRF) | |
| | i) Steel | 12 |
| | ii) Concrete | 12 |
| | 2. Intermediate moment resisting frames (IMRF), concrete (4) | 8 |
| | 3. Ordinary moment resisting frames (OMRF) | |
| | i) Steel | 6 |
| | ii) Concrete (5) | 5 |
| d. Dual System | 1. Shear walls | |
| | i) Concrete with steel or concrete SMRF | 12 |
| | ii) Concrete with steel OMRF | 6 |
| | iii) Concrete with concrete IMRF (4) | 9 |
| | iv) Masonry with steel or concrete SMRF | 8 |
| | v) Masonry with steel OMRF | 6 |
| | vi) Masonry with concrete IMRF (3) | 7 |
| | 2. Steel EBF | |
| | i) With steel SMRF | 12 |
| | ii) With steel OMRF | 6 |
| | 3. Concentric braced frame (CBF) | |
| | i) Steel with steel SMRF | 10 |
| | ii) Steel with steel OMRF | 6 |
| | iii) Concrete with concrete SMRF (3) | 9 |
| | iv) Concrete with concrete IMRF (3) | 6 |
| e. Special Structural Systems | See Sec 1.3.2, 1.3.3, 1.3.5 | — |
*Notes: (1) Basic Structural Systems are defined in Sec 1.3.2, Chapter 1. (2) See Sec 2.5.6.6 for combination of structural systems, and Sec 1.3.5 for system limitations. (3) Prohibited in Seismic Zone 3. (4) Prohibited in Seismic Zone 3 except as permitted in Sec 2.5.9.3. (5) Prohibited in Seismic Zones 2 and 3. Sec 1.7.2.6.*
**Table 6.2.25: Site Coefficient, S for Seismic Lateral Forces**
| Type | Description | Coefficient, S |
| ----- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------- |
| $S_1$ | A soil profile with either: a) A rock-like material characterized by a shear-wave velocity greater than 762 m/s or by other suitable means of classification, or b) Stiff or dense soil condition where the soil depth is less than 61 metres | 1.0 |
| $S_2$ | A soil profile with dense or stiff soil conditions, where the soil depth exceeds 61 metres | 1.2 |
| $S_3$ | A soil profile 21 metres or more in depth and containing more than 6 metres of soft to medium stiff clay but not more than 12 metres of soft clay | 1.5 |
| $S_4$ | A soil profile containing more than 12 metres of soft clay characterized by a shear wave velocity less than 152 m/s | 2.0 |
*Note: (1) The site coefficient shall be established from properly substantiated geotechnical data. In locations where the soil properties are not known in sufficient detail to determine the soil profile type, soil profile $S_3$ shall be used. Soil profile $S_4$ need not be assumed unless the building official determines that soil profile $S_4$ may be present at the site, or in the event that soil profile $S_4$ is established by geotechnical data.*
b) **Method B:** The fundamental period T may be calculated using the structural properties and deformational characteristics of the resisting elements in a properly substantiated analysis. This requirement may be satisfied by using the following formula:
$$
T = 2\pi \sqrt{ \sum_{i=1}^{n} w_i \delta_i^2 \Big/ g \sum_{i=1}^{n} f_i \delta_i } \tag{2.5.5}
$$
The values of $f_i$ represent any lateral force distributed approximately in accordance with the principles of Eq (2.5.6), (2.5.7) and (2.5.8) or any other rational distribution. The elastic deflections, $\delta_i$ shall be calculated using the applied lateral forces, $f_i$. The value of T determined from Eq (2.5.5) shall not exceed that calculated using Eq (2.5.3) by more than 40%.
#### 2.5.6.3 Vertical Distribution of Lateral Forces
In the absence of a more rigorous procedure, the total lateral force, which is the base shear V, shall be distributed along the height of the structure in accordance with Eq (2.5.6), (2.5.7) and (2.5.8):
$$
V = F_t + \sum_{i=1}^{n} F_i \tag{2.5.6}
$$
where, $F_i$ = Lateral force applied at storey level -i and
$F_t$ = Concentrated lateral force considered at the top of the building in addition to the force $F_n$.
The concentrated force, $F_t$ acting at the top of the building shall be determined as follows:
$$
F_t = 0.07\,TV \leq 0.25\,V \quad \text{when } T > 0.7 \text{ second} \tag{2.5.7a}
$$
$$
F_t = 0.0 \quad \text{when } T \leq 0.7 \text{ second} \tag{2.5.7b}
$$
The remaining portion of the base shear $(V - F_t)$, shall be distributed over the height of the building, including level-n, according to the relation:
$$
F_x = \frac{(V - F_t) w_x h_x}{\sum_{i=1}^{n} w_i h_i} \tag{2.5.8}
$$
At each storey level-x, the force $F_x$ shall be applied over the area of the building in proportion to the mass distribution at that level.
#### 2.5.6.4 Horizontal Distribution of Shear
The design storey shear $V_x$, in any storey x is the sum of the forces $F_x$ and $F_t$ above that storey. $V_x$ shall be distributed to the various elements of the vertical lateral force resisting system in proportion to their rigidities, considering the rigidity of the floor or roof diaphragm. Allowance shall also be made for the increased shear arising due to any horizontal torsional moments as specified in Sec 2.5.6.5.
#### 2.5.6.5 Horizontal Torsional Moments
Provision shall be made for the increased shears resulting from horizontal torsion where floor diaphragms are not flexible.
The torsional design moment at a given storey shall be the moment resulting from eccentricities between applied design lateral forces at levels above that storey and the vertical resisting elements in that storey plus an accidental torsional moment.
The accidental torsional moment in any storey shall be determined assuming the storey mass to be displaced from the calculated centre of mass in each direction a distance equal to 5% of the building dimension at that level perpendicular to the direction of the force under consideration.
Where torsional irregularity exists (Plan Irregularity Type I as defined in Table 6.1.4) the effects shall be accounted for by increasing the accidental torsion at each level by an amplification factor, $A_x$ determined from the formula:
$$
A_x = \left[ \delta_{max} / (1.2\delta_{avg}) \right]^2 \leq 3.0 \tag{2.5.9}
$$
where, $\delta_{max}$ = The maximum displacement at level-x.
$\delta_{avg}$ = The average of the displacements at extreme positions of the building at level-x.
The more severe loading for each element shall be considered for design.
#### 2.5.6.6 Combination of Structural Systems
When structural systems defined in Sec 1.3.2 are combined to be incorporated into the same structure, the following requirements shall be satisfied:
a) **Vertical Combinations:** The value of the response modification coefficient, R used in the design of any storey for a given direction shall not be greater than that used for the storey above. However, this requirement need not apply to a storey where the dead load above that storey is less than 10 per cent of the total dead weight of the structure.
Structures may be designed using the procedures of Sec 2.5.6 under the following conditions:
i) The type of structure is designed using the lowest value of R for the lateral force resisting systems used, or
ii) The following procedure is used for structures conforming to Sec 2.5.5.1a(iv).
1. The flexible upper portion, shall be designed as a separate structure, supported laterally by the rigid lower portions using the appropriate value of R.
2. The rigid lower portion shall be designed as a separate structure using the appropriate value of R. The reactions from the upper portion shall be increased by the ratio of the R values of the two portions. These factored reactions shall be applied at the top of the rigid lower portion in addition to the forces determined for the lower portion itself.
b) **Combinations Along Different Axes:**
i) In Seismic Zone 3, where a structure has a Bearing Wall System in only one direction, the value of R used for the orthogonal direction shall not be greater than that used for the Bearing Wall System defined in Sec 1.3.2.
ii) Any combination of Building Frame Systems, Dual Systems, or Moment Resisting Frame Systems defined in Sec 1.3.2 may be used to resist design seismic forces in structures less than 50 m in height. Only combinations of Dual Systems and Special Moment Resisting Frames (SMRF) are allowed to resist the design seismic forces in structures exceeding 50 m in height in Seismic Zone 3.
### 2.5.7 Dynamic Response Method
The Dynamic Response Method, where used, shall conform to the criteria established in this section. The analysis of the structure shall be based on an established principle of mechanics, using a mathematical model specified in Sec 1.2.6.1(a) and one of the dynamic analysis procedures given in Sec 2.5.7.2 and 2.5.7.3.
The mass and mass moments of inertia of various components of a structure, required for the dynamic analysis, shall be calculated based on the seismic dead load specified in Sec 2.5.5.2.
#### 2.5.7.1 Ground Motion
The ground motion representation as set out in this section shall, as a minimum, be one having 20% probability of being exceeded in 50 years and may be one of the following:
a) **Response Spectrum:** The response spectrum to be used in the dynamic analysis shall be any one of the following:
i) **Site Specific Design Spectra:** A site specific response spectra shall be developed based on the geologic, tectonic, seismologic, and soil characteristics associated with the specific site. The spectra shall be developed for a damping ratio of 0.05 unless a different value is found to be consistent with the expected structural behaviour at the intensity of vibration established for the site.
ii) **Normalized Response Spectra:** In absence of a site-specific response spectra, the normalized response spectra given in Fig 6.2.11 shall be used in the dynamic analysis procedure given in Sec 2.5.7.2.
b) **Time History:** Ground motion time history developed for the specific site shall be representative of actual earthquake motions for the directions under consideration. Response spectra from time history, either individually or in combination, shall approximate the site-specific design spectra conforming to paragraph a(i) above.
![Fig 6.2.11: Normalized Response Spectra for 5% Damping Ratio]()
*Fig 6.2.11: Normalized Response Spectra for 5% Damping Ratio. Curves shown for Soil Type $S_1$ (Rock and Stiff Soils), Soil Type $S_2$ (Deep Cohesionless or Stiff Clay Soils), and Soil Type $S_3$ (Soft to Medium Clay and Sand). Notes: (1) $S_a$ = spectral acceleration, g = acceleration due to gravity, Z = seismic zone coefficient. (2) For structures on Soil Type $S_4$, refer to Sec 2.5.7.1(c).*
c) **Structures on Soil Profile Type $S_4$:** The following provisions shall apply when required by Sec 2.5.5.1 b(iv):
i) The ground motion representation shall be developed in accordance with paragraphs a(i) and b above.
ii) Possible amplification of building response due to soil-structure interaction and lengthening of building period caused by inelastic behaviour shall be considered.
iii) The base shear determined by these procedures may be reduced to a design base shear, V, by dividing by a factor not greater than the appropriate R value for the structure but shall not be less than that required by Sec 2.5.7.2c(i).
d) **Vertical Component:** The vertical component of ground motion may be defined by scaling the corresponding horizontal ground accelerations by a factor of two-thirds. Alternative factors may be used when substantiated by site-specific data.
#### 2.5.7.2 Response Spectrum Analysis
Where this procedure is used, an elastic dynamic analysis of a structure shall be performed based on the criteria set forth in this section with a mathematical model conforming to Sec 1.2.6.1(a) and using a response spectrum as specified in Sec 2.5.7.1(a). The analysis shall include the peak dynamic response of all modes having a significant contribution to total structural response. Peak modal response shall be calculated using the ordinates of the appropriate response spectrum curve which correspond to the modal periods. Maximum modal contributions shall be combined in a statistical manner to obtain an approximate total structural response.
a) **Number of Modes:** The requirement that all significant modes be included may be satisfied by demonstrating that, for the modes considered, at least 90 per cent of the participating mass of the structure is included in the calculation of response for each principal horizontal direction.
b) **Combination of Modes:** The peak member forces, displacements, storey forces, storey shears, and base reactions for each mode shall be combined using established procedures in order to estimate resultant maximum values of these response parameters. When three dimensional models are used for analysis, modal interaction effects shall be considered when combining modal maximum.
c) **Scaling of Results:** Where the base shear for a given direction, determined by this procedure, is different from the base shear obtained by using the procedure of Sec 2.5.6.1, it shall be adjusted as follows:
i) When the base shear is less than that determined from Sec 2.5.6.1, the following values shall be taken:
1. The value of the base shear as obtained from Sec 2.5.6.1, for irregular structures.
2. 90 per cent of the value from Sec 2.5.6.1 for regular structures except that the base shear shall not be less than 80 per cent of that determined using T from Sec 2.5.6.2(a).
ii) When the base shear is greater than that determined from Sec 2.5.6.1, the value need not exceed that required by c(i) above, except for structures required to conform to Sec 2.5.7.1(c).
All corresponding response parameters, including deflections, member forces and moments, shall be adjusted in proportion to the adjusted base shear.
d) **Torsion:** The analysis shall account for torsional effects, including accidental torsional effects as prescribed in Sec 2.5.6.5. Where three-dimensional models are used for analysis, effects of accidental torsion shall be accounted for by appropriate adjustments in the model such as adjustment of mass locations, or by the equivalent static procedure provided in Sec 2.5.6.5.
#### 2.5.7.3 Time History Analysis
When this procedure is followed, an elastic or inelastic dynamic analysis of a structure shall be made using a mathematical model of the structure specified in Sec 1.2.6.1(a) and applying at its base or any other appropriate level, a ground motion time history as specified in Sec 2.5.7.1(b). The time-dependent dynamic response of the structure shall be obtained through numerical integration of its equations of motion.
### 2.5.8 Seismic Lateral Forces on Components and Equipment Supported by Structures
#### 2.5.8.1 Lateral Forces on Structural and Non-structural Components, and Equipment
The minimum design seismic lateral forces on elements of structures, non-structural components, equipment and their attachments including anchorage and bracing to the main structural system shall be determined in accordance with the formula:
$$
F' = ZI'C'W' \tag{2.5.10}
$$
where, $F'$ = Total lateral seismic force
$Z$ = Seismic zone coefficient as given in Table 6.2.22
$I'$ = Structure Importance Coefficient for components as given in Table 6.2.23
$C'$ = Horizontal force Coefficient as specified in Sec 2.5.8.2.
$W'$ = Weight of an element, component or piece of equipment.
The total lateral seismic force, $F'$ obtained from Eq (2.5.10) shall be distributed in proportion to the mass distribution of the element, component or piece of equipment. These forces shall be applied in the horizontal direction to cause the most critical loading for design. Friction resulting from gravity forces shall not be considered to provide resistance to seismic forces.
Seismic lateral forces on attachments for floor- or roof-mounted equipment weighing less than 1.8 kN and for furniture need not be determined for design purposes.
#### 2.5.8.2 Horizontal Force Coefficient C'
The value of the coefficient $C'$ shall be determined as follows:
a) For elements of structure and non-structural components, and for rigid or rigidly supported equipment supported by structures above grade, $C'$ shall be taken as those given in Table 6.2.26.
b) For non-rigid or flexibly supported equipment supported by a structure and located above grade on a structure, the seismic lateral force shall be determined considering the dynamic properties of both the equipment and those of the structure which supports it, but the value of $C'$ shall not be less than that listed in Table 6.2.26. In the absence of an analysis or empirical data, the value of $C'$ shall be taken as twice the value listed in Table 6.2.26 but it need not exceed 2.0.
For piping, ducting and conduit systems which are constructed of ductile materials and connections, the values of $C'$ may be taken as those given in Table 6.2.26.
c) The value of $C'$ for elements, or components and equipment laterally self-supported and located at or below ground level may be two-thirds of the value set forth in Table 6.2.26. However, the design lateral forces obtained from Eq (2.5.10) for these elements shall not be less than that as would be obtained using the provision of Sec 2.5.9.
#### 2.5.8.3 Seismic Lateral Forces on Floor or Roof Diaphragms
Seismic lateral forces on floor and roof diaphragms and collector elements shall be determined in accordance with the following formula:
$$
F'_x = \frac{\left(F_t + \sum_{i=x}^{n} F'_i \right)}{\sum_{i=x}^{n} w_i} w'_x \tag{2.5.11}
$$
a) The force $F'_x$ determined from Eq (2.5.11) need not exceed $0.75\,ZI\,w'_x$, but it shall not be less than $0.35\,ZI$.
b) When the diaphragm is required to transfer lateral forces from the vertical resisting elements above the diaphragm to other vertical resisting elements below the diaphragm due to offset in the placement of the elements or to changes in stiffness in the vertical elements, these forces shall be added to those determined from Eq (2.5.11).
### 2.5.9 Seismic Lateral Forces on Non-Building Structures
Non-building structures shall include all self-supporting structures other than buildings that carry gravity loads and resist the effects of earthquake and other lateral forces. Determination of seismic lateral forces for such structures shall be based on the following provisions:
#### 2.5.9.1 Seismic Dead Load
For non-building structures, the seismic dead load, W shall include all loads defined for buildings in Sec 2.5.5.2. In addition, W shall include all normal operating contents for structures such as tanks, vessels, bins and piping.
#### 2.5.9.2 Fundamental Period
For structures with primary framing systems similar to buildings, the fundamental period T, shall be determined in accordance with Sec 2.5.6.2. For other structures, T shall be obtained by using a rational method such as Method B of Sec 2.5.6.2.
#### 2.5.9.3 Structures Similar to Buildings
The seismic lateral forces on structures with primary framing systems similar to buildings (i.e. structural systems listed in Table 6.2.24) shall be determined in accordance with the provisions of Sec 2.5.5 through 2.5.8 with following modifications:
a) Intermediate moment resisting frames (IMRF) may be used in structures within Seismic Zone 3 and in structure importance categories III through V, if, (i) the structure is less than 15 m in height, and (ii) $R = 4.0$ is used in load calculations.
b) Seismic dead load and structure period shall be calculated in accordance with Sec 2.5.5.2 and 2.5.9.2 respectively.
**Table 6.2.26: Horizontal Force Coefficient, C' for Elements, Components and Equipment**
| Elements of Structures and Non-structural Components and Equipment | Value of C' |
| --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------- |
| **I. Elements of Structures** | |
| 1. Walls including the following: | |
| a. Unbraced (cantilevered) parapets | 2.00 |
| b. Other exterior walls above the ground floor (2,3) | 0.75 |
| c. All interior bearing and nonbearing walls and partitions (3) | 0.75 |
| d. Masonry or concrete fences over 1.8 m high | 0.75 |
| 2. Penthouse (except when framed by an extension of the structural frame) | 0.75 |
| 3. Connections for prefabricated structural elements other than walls, with force applied at centre of gravity (4) | 0.75 |
| 4. Diaphragms (3,5) | — |
| **II. Non-structural Components** | |
| 1. Exterior and interior ornamentation and appendages | 2.00 |
| 2. Chimneys, stacks, trussed towers and tanks on legs: | |
| a. Supported on or projecting as an unbraced cantilever above the roof more than one-half their total height | 2.00 |
| b. All others, including those supported below the roof with unbraced projection above the roof less than one-half their height, or braced or guyed to the structural frame at or above their centres of mass | 0.75 |
| 3. Signs and billboards | 2.00 |
| 4. Storage racks (including contents) | 0.75 |
| 5. Anchorage for permanent floor-supported cabinets and book stacks more than 1.5 m in height (including contents) | 0.75 |
| 6. Anchorage for suspended ceilings and light fixtures (4,6) | 0.75 |
| 7. Access floor systems (4,7) | 0.75 |
| **III. Equipment** | |
| 1. Tanks and vessels (including contents), together with support systems and anchorage | 0.75 |
| 2. Electrical, mechanical and plumbing equipment and associated conduit, ductwork and piping, and machinery (8) | 0.75 |
*Notes: (1) See Sec 2.5.8.2 for items supported at or below grade. (2) See Sec 1.7.2.3 and 2.5.8.2. (3) Where flexible diaphragms provide lateral support for walls and partitions, the value of C' for anchorage shall be increased 50 per cent for the centre one-half of the diaphragm span. (4) Applies to Seismic Zones 2 and 3 only. (5) See Sec 1.7.2.9 and 2.5.8.3. (6) Ceiling weight shall include all light fixtures and other equipment or partitions which are laterally supported by the ceiling. For the purpose of determining the seismic force, a ceiling weight of not less than 0.2 kN/m² shall be used. Ceilings constructed of lath and plaster or gypsum board, screw or nail attached to suspended members that support a ceiling at one level extending from wall to wall need not be analysed provided the walls are not over 15 m apart. (7) W' for access floor systems shall be the dead load of the access floor systems plus 25 per cent of the floor live load plus a 0.5 kN/m² partition load allowance. (8) Equipment includes, but is not limited to, boilers, chillers, heat exchangers, pumps, air-handling units, cooling towers, control panels, motors, switchgear, transformers and life-safety equipment. It also includes major conduit, ducting and piping serving such equipment and fire sprinkler systems. See Sec 2.5.8.2 for additional requirements for determining C' for non-rigid or flexibly mounted equipment.*
#### 2.5.9.4 Rigid Structures
For rigid structures (i.e. those with period, T \< 0.06 second) including their anchorage, the total lateral force, V shall be determined in accordance with the relation:
$$
V = 0.5\,ZIW \tag{2.5.12}
$$
#### 2.5.9.5 Flat-bottom Tanks at or Below Grade
Seismic forces for flat-bottom tanks or other tanks with supported bottoms, founded at or below grade, shall be calculated using the procedure of Sec 2.5.9.4 considering the entire weight of the tank and its contents. Alternatively, such forces may be determined using one of the following methods.
a) A response spectrum analysis, which includes consideration of the actual ground motion anticipated at the site and the inertial effects of the contained fluid.
b) A substantiated analysis prescribed for the particular type of tank provided that the seismic zones and Structure Importance Categories are in conformance with Fig 6.2.10 and Sec 1.2.3 respectively.
#### 2.5.9.6 Other Structures
For structures (other than buildings), which are not covered by Sec 2.5.9.3 through 2.5.9.5, the minimum seismic lateral forces shall be determined in accordance with the following provisions:
a) The total lateral seismic force, V shall be determined using the provisions of Sec 2.5.6 with the coefficient R taken from Table 6.2.27. However, the ratio C/R shall not be less than 0.5.
**Table 6.2.27: Coefficient, R for Non-Building Structures**
| Structure Type | R |
| ----------------------------------------------------------------------------------------------------------- | - |
| Tanks, vessels or pressurized spheres on braced or unbraced legs | 3 |
| Cast-in-place concrete silos and chimneys having walls continuous to the foundation | 5 |
| Distributed mass cantilever structures such as stacks, chimneys, silos and skirt-supported vertical vessels | 4 |
| Trussed towers (free standing or guyed), guyed stacks and chimneys | 4 |
| Inverted pendulum-type structures | 3 |
| Cooling towers | 5 |
| Bins and hoppers on braced or unbraced legs | 4 |
| Storage racks | 5 |
| Signs and billboards | 5 |
| Amusement structures and monuments | 3 |
| All other self-supporting structures not otherwise covered | 4 |
b) The vertical distribution of the total lateral seismic force, V, may be determined by one of the following procedures:
1. Using provisions of Sec 2.5.6.3.
2. Using procedures of Sec 2.5.7.
**Exception:** For irregular structures assigned to Structure Importance Categories I and II, which cannot be modeled as a single mass, the procedures of Sec 2.5.7 shall be used.
c) When any other established standard or method is used as a basis for obtaining the seismic lateral forces for a particular type of non-building structure covered by this section, such a standard may be used subject to the following limitations:
i) The Seismic Zones and Structure Importance Categories shall be in conformance with the requirements of Sec 2.5.4 and 1.2.3 respectively.
ii) The values for total lateral force and total base overturning moment used in design shall not be less than 80% of the values which would be obtained using these provisions.
## 2.6 Miscellaneous Loads
### 2.6.1 General
The procedures and limitations for the determination of selected miscellaneous loads are provided in this section. Loads that are not specified in this section or elsewhere in this chapter, may be determined based on information from reliable references or specialist advice may be sought.
### 2.6.2 Definitions
The following definitions and notation shall apply to the provisions of this section only.
**ESSENTIAL FACILITIES:** Buildings and structures which are necessary to remain functional during an emergency or a post disaster period.
**RATIONAL ANALYSIS:** An analysis based on established methods or theories using mathematical formulae and actual or appropriately assumed data.
**SITE-SPECIFIC DATA:** Data obtained either from measurements taken at a site or from substantiated field information required specifically for the structure concerned.
### 2.6.3 Rain Loads
Rain loads shall be determined in accordance with the following provisions.
#### 2.6.3.1 Blocked Drains
Each portion of a roof shall be designed to sustain the load from all rainwater that could be accumulated on it if the primary drainage system for that portion is undersized or blocked. Ponding instability shall be considered in this situation.
#### 2.6.3.2 Controlled Drainage
Roofs equipped with controlled drainage provisions shall be designed to sustain all rainwater loads on them to the elevation of the secondary drainage system plus 0.25 kN/m². Ponding instability shall be considered in this situation.
### 2.6.4 Loads Due to Flood and Surge
For the determination of flood and surge loads on a structural member, consideration shall be given to both hydrostatic and hydrodynamic effects. Required loading shall be determined in accordance with the established principles of mechanics based on site specific criteria and in compliance with the following provisions of this section. For essential facilities like cyclone and flood shelters and for hazardous facilities specified in Table 6.1.1, values of maximum flood elevation, surge height, wind velocities etc., required for the determination of flood and surge load, shall be taken corresponding to 100-year return period. For structures other than essential and hazardous facilities, these values, shall be based on 50-year return period.
#### 2.6.4.1 Flood Loads on Structures at Inland Areas
For structures sited at inland areas subject to flood, loads due to flood shall be determined considering hydrostatic effects which shall be calculated based on the flood elevation of 50-year return period. For river-side structures such as that under Exposure C specified in Sec 2.4.4.1, hydrodynamic forces, arising due to approaching wind-generated waves shall also be determined in addition to the hydrostatic load on them. In this case, the amplitude of such wind-induced water waves shall be obtained from site-specific data.
#### 2.6.4.2 Flood and Surge Loads on Structures at Coastal Areas
For structures sited at coastal areas, the hydrostatic and hydrodynamic loads shall be determined as follows:
a) **Hydrostatic Loads:** The hydrostatic loads on structural elements and foundations shall be determined based on the maximum static height of water, $H_m$, produced by floods or surges as given by the relation:
$$
H_m = \max(h_s, h_f) \tag{2.6.1}
$$
where, $h_f = y_T - y_g$ and (2.6.2)
$h_s$ = Maximum surge height as specified in a(i) below.
$y_T$ = Elevation of the extreme surface water level corresponding to a T-year return period specified in (ii) below, metres
$y_g$ = Elevation of ground level at site, metres.
i) **Maximum Surge Height, $h_s$:** The maximum surge height, $h_s$, associated with cyclones, shall be that corresponding to a 50-year or a 100-year return period as may be applicable, based on site specific analysis. In the absence of a more rigorous site specific analysis, the following relation may be used:
$$
h_s = h_T - (x-1)k \tag{2.6.3}
$$
where,
$h_T$ = design surge height corresponding to a return period of T-years at sea coast, in metres, given in Table 6.2.28.
$x$ = distance of the structure site measured from the spring tide high-water limit on the sea coast, in km; $x = 1$, if $x < 1$.
$k$ = rate of decrease in surge height in m/km; the value of $k$ may be taken as 1/2 for Chittagong-Cox's Bazar-Teknaf coast and as 1/3 for other coastal areas.
ii) **Extreme Surface Water Level, $y_T$:** The elevation of the extreme surface water level, $y_T$ for a site, which may not be associated with a cyclonic storm surge, shall be that obtained from a site specific analysis corresponding to a 50-year or a 100-year return period. Values of $y_T$ are given in Table 6.2.29 for selected coastal locations which may be used in the absence of any site specific data.
b) **Hydrodynamic Loads:** The hydrodynamic load applied on a structural element due to wind-induced local waves of water, shall be determined by a rational analysis using an established method and based on site specific data. In the absence of a site-specific data the amplitude of the local wave, to be used in the rational analysis, shall be taken as $h_w = h_s/4 \geq 1$ m, where, $h_s$ is given in Sec 2.6.4.2(a). Such forces shall be calculated based on 50-year or 100-year return period of flood or surge. The corresponding wind velocities shall be 260 km/h or 289 km/h respectively.
#### 2.6.4.3 Breakaway Walls
When non-structural walls, partitions or other non-structural elements located below the maximum flood or surge elevation, are required to break away under high tides or wave action, such non-structural elements shall be designed to sustain a maximum uniformly distributed load of 1.0 kN/m² but not less than 0.5 kN/m² applied on a vertical projection of the area.
### 2.6.5 Temperature Effects
Temperature effects, if significant, shall be considered in the design of structures or components thereof in accordance with the provision of this section.
In determining the temperature effects on a structure, the following provisions shall be considered:
a) The temperatures indicated, shall be the air temperature in the shade. The range of the variation in temperature for a building site shall be taken into consideration.
b) Effects of the variation of temperature within the material of a structural element shall be accounted for by one of the following methods.
i) relieve the stresses by providing adequate numbers of expansion or contraction joints,
ii) design the structural element to sustain additional stresses due to temperature effects.
**Table 6.2.28: Design Surge Heights at the Sea Coast, $h_T$**\*
| Coastal Region | Surge Height at the Sea Coast, $h_T$ (m) T = 50-year (1) | Surge Height at the Sea Coast, $h_T$ (m) T = 100-year (2) |
| ---------------------------------------------------- | :------------------------------------------------------: | :-------------------------------------------------------: |
| Teknaf to Cox's Bazar | 4.5 | 5.8 |
| Chakaria to Anwara, and Maheshkhali-Kutubdia Islands | 7.1 | 8.6 |
| Chittagong to Noakhali | 7.9 | 9.6 |
| Sandwip, Hatiya and all islands in this region | 7.9 | 9.6 |
| Bhola to Barguna | 6.2 | 7.7 |
| Sarankhola to Shyamnagar | 5.3 | 6.4 |
*Values prepared from information obtained from Annex-D3, MCSP.*
*Note: (1) These values may be used in the absence of site specific data for structures other than essential facilities listed in Table 6.1.1. (2) These values may be used in the absence of site specific data for essential facilities listed in Table 6.1.1.*
**Table 6.2.29: Extreme Surface Water Levels During Monsoon at Selected Locations of the Coastal Area above PWD Datum, $y_T$**\*
| Location | Thana | $y_T$ (m) T=50 years (1) | $y_T$ (m) T=100 years (2) |
| ----------------------- | ----------- | :----------------------: | :-----------------------: |
| Teknaf | Teknaf | 2.33 | 2.44 |
| Cox's Bazar | Cox's Bazar | 3.84 | 3.88 |
| Shaflapur | Moheshkhali | 4.67 | 4.87 |
| Lemsikhali | Kutubdia | 4.95 | 5.19 |
| Banigram | Patiya | 5.05 | 5.24 |
| Chittagong | Bandar | 4.72 | 4.88 |
| Patenga | Bandar | 4.08 | 4.16 |
| Sonapur | Sonagazi | 7.02 | 7.11 |
| Sandwip | Sandwip | 6.09 | 6.2 |
| Companyganj | Companyganj | 7.53 | 7.94 |
| Hatiya | Hatiya | 5.55 | 5.76 |
| Daulatkhan | Daulatkhan | 4.62 | 4.72 |
| Dashmina | Dashmina | 3.60 | 3.73 |
| Galachipa | Galachipa | 3.79 | 3.92 |
| Patuakhali | Patuakhali | 2.87 | 3.03 |
| Khepupara | Kalapara | 2.93 | 3.02 |
| Bamna | Bamna | 3.32 | 3.37 |
| Patharghata | Patharghata | 3.65 | 3.84 |
| Raenda | Sarankhola | 3.66 | 3.75 |
| Chardouni | Patharghata | 4.41 | 4.66 |
| Mongla | Monglaport | 3.23 | 3.36 |
| Kobodak (river estuary) | Shyamnagar | 3.51 | 3.87 |
| Kaikhali | Shyamnagar | 3.94 | 4.12 |
*Values prepared from information obtained from Annex-D3, MCSP*
*Note: (1) These values may be used in the absence of site specific data for structures in Structure Importance Categories III, IV and V listed in Table 6.1.1. (2) These values may be used in the absence of site specific data for structures in Structure Importance Categories I and II listed in Table 6.1.1.*
c) when the method b(ii) above is considered to be applicable, the structural analysis shall take into account the following:
i) the variation in temperature within the material of the structural element, exposure condition of the element and the rate at which the material absorb or radiate heat.
ii) the warping or any other distortion caused due to temperature changes and temperature gradient in the structural element.
d) When it can be demonstrated by established principle of mechanics or by any other means that neglecting some or all of the effects of temperature, does not affect the safety and serviceability of the structure, the temperature effect can be considered insignificant and need not be considered in design.
### 2.6.6 Soil and Hydrostatic Pressure
For structures or portions thereof, lying below ground level, loads due to soil and hydrostatic pressure shall be determined in accordance with the provisions of this section and applied in addition to all other applicable loads.
#### 2.6.6.1 Pressure on Basement Wall
In the design of basement walls and similar vertical or nearly vertical structures below grade, provision shall be made for the lateral pressure of adjacent soil. Allowance shall be made for possible surcharge due to fixed or moving loads. When a portion or the whole of the adjacent soil is below the surrounding water table, computations shall be based on the submerged unit weight of soil, plus full hydrostatic pressure.
#### 2.6.6.2 Uplift on Floors
In the design of basement floors and similar horizontal or nearly horizontal construction below grade, the upward pressure of water, if any, shall be taken as the full hydrostatic pressure applied over the entire area. The hydrostatic head shall be measured from the underside of the construction.
### 2.6.7 Loads Due to Explosions
Loads on buildings or portions thereof, shall be assessed in accordance with the provisions of this section.
#### 2.6.7.1 Explosion Effects in Closed Rooms
a) **Determination of Loads and Response:** Internal overpressure developed from an internal explosion such as that due to leaks in gas pipes, evaporation of volatile liquids, internal dust explosion etc., in rooms of sizes comparable to residential rooms and with ventilation areas consisting of window glass breaking at a pressure of 4 kN/m² (3-4 mm machine made glass) may be calculated from the following method:
i) The overpressure, $q_o$ provided in Fig 6.2.12(a) shall be assumed to depend on a factor $A_o/v$, where, $A_o$ is the total window area in m² and $v$ is the volume in m³ of the room considered,
ii) The internal pressure shall be assumed to act simultaneously upon all walls and floors in one closed room, and
iii) The action $q_o$ obtained from Fig 6.2.12(a) may be taken as static action.
When a time dependent response is required, an impulsive force function similar to that shown in Fig 6.2.12(b) shall be used in a dynamic analysis, where $t_1$ is the time from the start of combustion until maximum pressure is reached and $t_2$ is the time from maximum pressure to the end of combustion. For $t_1$ and $t_2$ the most unfavourable values shall be chosen in relation to the dynamic properties of the structures. However, the values shall be chosen within the intervals as given in Fig 6.2.12(b).
The pressure may be applied solely in one room or in more than one room at the same time. In the latter case, all rooms are incorporated in the volume $v$. Only windows or other similarly weak and light weight structural elements may be taken as ventilation areas even though certain limited structural parts break at pressures less than $q_o$.
![Fig 6.2.12: Magnitude and Distribution of Internal Pressure in a Building Due to Internal Gas Explosion]()
*Fig 6.2.12: Magnitude and Distribution of Internal Pressure in a Building Due to Internal Gas Explosion. (a) Internal Pressure as a Function of $A_o/v$. (b) Variation of Pressure, $q$ as a Function of Time, $t$. $0.1s \leq t_1 \leq 1.0s$; $1.0s \leq t_2 \leq 10.0s$.*
b) **Limitations:** Procedure for determining explosion loads given in (a) above shall have the following limitations:
i) Values of $q_o$ given in Fig 6.2.12(a) are based on tests with gas explosions in room corresponding to ordinary residential flats, and may be applied to considerably different conditions with caution after appropriate adjustment of the values based on more accurate information.
ii) Fig 6.2.12 shall be taken as a guide only, and probability of occurrence of an explosion shall be checked in each case using appropriate values.
#### 2.6.7.2 Minimum Design Pressure
Walls, floors and roofs and their supporting members separating a use from an explosion exposure, shall be designed to sustain the anticipated maximum load effects resulting from such use including any dynamic effects, but for a minimum internal pressure or suction of 5 kN/m², in addition to all other loads specified in this chapter.
#### 2.6.7.3 Design Pressure on Relief Vents
When pressure-relief vents are used, such vents shall be designed to relieve at a maximum internal pressure of 1.0 kN/m².
#### 2.6.7.4 Loads Due to Other Explosions
Loads arising from other types of explosions, such as those from external gas cloud explosions, external explosions due to high explosives (TNT) etc. shall be determined, for specific cases, by rational analyses based on information from reliable references or specialist advice shall be sought.
### 2.6.8 Vertical Forces on Air Raid Shelters
For the design of air raid shelters located in a building e.g. in the basement below ground level, the characteristic vertical load shall be determined in accordance with provisions of Sec 2.6.8.1 below.
#### 2.6.8.1 Characteristic Vertical Loads
Buildings in which the individual floors are acted upon by a total distributed live load of up to 5.0 kN/m², vertical forces on air raid shelters generally located below ground level, such as a basement, shall be considered to have the characteristic values provided in Table 6.2.30. In the case of buildings having floors that are acted upon by a live load larger than 5.0 kN/m², above values shall be increased by the difference between the average live loads on all storeys above the one used as the shelter and 5.0 kN/m².
**Table 6.2.30: Characteristic Vertical Loads for an Air Raid Shelter in a Building**
| No. of Storeys (1) Above the Air Raid Shelter | Vertical Load kN/m² |
| ----------------------------------------------------------------------------------- | :-----------------: |
| ≤ 2 | 28 |
| 3 - 4 | 34 |
| ≥ 4 | 41 |
| Buildings of particularly stable construction irrespective of the number of storeys | 28 (2) |
*Note: (1) Storeys shall mean every usable storey above the shelter floor. (2) Buildings of particularly stable construction shall mean buildings having bearing structural elements made from reinforced in-situ concrete.*
### 2.6.9 Loads on Helicopter Landing Areas
In addition to all other applicable loads provided in this chapter, including the dead load, the minimum live load on helicopter landing or touch down areas shall be one of the loads $L_1$, $L_2$ or $L_3$ as given below producing the most unfavourable effect:
i) $L_1 = W_1$ (2.6.4a)
ii) $L_2 = kW_2$ (2.6.4b)
iii) $L_3 = w$ (2.6.4c)
where, $W_1$ = Actual weight of the helicopter in kN,
$W_2$ = Fully loaded weight of the helicopter in kN,
$w$ = A distributed load of 5.0 kN/m²,
$k$ = 0.75 for helicopters equipped with hydraulic-type shock absorbers, and
$\phantom{k =}$ 1.5 for helicopters with rigid or skid-type landing gear.
The live load, $L_1$ shall be applied over the actual areas of contact of landing. The load, $L_2$ shall be a single concentrated load including impact applied over a 300 mm x 300 mm area. The loads $L_1$ and $L_2$ may be applied anywhere within the landing area to produce the most unfavourable effects of load.
### 2.6.10 Erection and Construction Loads
All loads required to be sustained by a structure or any portion thereof due to placing or storage of construction materials and erection equipment including those due to operation of such equipment shall be considered as erection loads. Provisions shall be made in design to account for all stresses due to such loads.
## 2.7 Combinations of Loads
### 2.7.1 General
Buildings, foundations and structural members shall be investigated for adequate strength to resist the most unfavourable effect resulting from the various combinations of loads provided in this section. The combination of loads may be selected using the provisions of either Sec 2.7.4 or 2.7.5 whichever is applicable. However, once Sec 2.7.4 or 2.7.5 is selected for a particular construction material, it must be used exclusively for proportioning elements of that material throughout the structure. In addition to the load combinations given in Sec 2.7.4 and 2.7.5 any other specific load combination provided elsewhere in this Code shall also be investigated to determine the most unfavourable effect.
The most unfavourable effect of loads may also occur when one or more of the contributing loads are absent, or act in the reverse direction. Loads such as $F$, $H$ or $S$ shall be considered in design when their effects are significant. Floor live loads shall not be considered where their inclusion result in lower stresses in the member under consideration. The most unfavourable effects from both wind and earthquake loads shall be considered where appropriate, but they need not be assumed to act simultaneously.
### 2.7.2 Definitions
**ALLOWABLE STRESS DESIGN METHOD (ASD):** A method for proportioning structural members such that the maximum stresses due to service loads obtained from an elastic analysis does not exceed a specified allowable value. This is also called Working Stress Design Method (WSD).
**DESIGN STRENGTH:** The product of the nominal strength and a resistance factor.
**FACTORED LOAD:** The product of the nominal load and a load factor.
**LIMIT STATE:** A condition in which a structure or component becomes unfit for service and is judged either to be no longer useful for its intended function (serviceability limit state) or to be unsafe (strength limit state).
**LOAD EFFECTS:** Forces, moments, deformations and other effects produced in structural members and components by the applied loads.
**LOAD FACTOR:** A factor that accounts for unavoidable deviations of the actual load from the nominal value and for uncertainties in the analysis that transforms the load into a load effect.
**LOADS:** Forces or other actions that arise on structural systems from the weight of all permanent constructions, occupants and their possessions, environmental effects, differential settlement, and restrained dimensional changes. Permanent loads are those loads in which variations in time are rare or of small magnitude. All other loads are variable loads.
**NOMINAL LOADS:** The magnitudes of the loads such as dead, live, wind, earthquake etc. specified in Sec 2.2 through 2.6 of this chapter.
**NOMINAL STRENGTH:** The capacity of a structure or component to resist the effects of loads, as determined by computations using specified material strengths and dimensions and formulas derived from accepted principles of structural mechanics or by field tests or laboratory tests of scaled models, allowing for modelling effects and differences between laboratory and field conditions.
**RESISTANCE FACTOR:** A factor that accounts for unavoidable deviations of the actual strength from the nominal value and the manner and consequences of failure. This is also known as strength reduction factor.
**STRENGTH DESIGN METHOD:** A method of proportioning structural members using load factors and resistance factors satisfying both the applicable limit state conditions. This is also known as Load Factor Design Method (LFD) or Ultimate Strength Design Method (USD).
**WORKING STRESS DESIGN METHOD (WSD):** See ALLOWABLE STRESS DESIGN METHOD.
### 2.7.3 Symbols and Notation
$D$ = dead load consisting of: a) weight of the member itself, b) weight of all materials of construction incorporated into the building to be permanently supported by the member, including built-in partitions, c) weight of permanent equipment.
$E$ = earthquake load
$E'$ = amplified earthquake load equal to $(0.375R)E$
$F$ = loads due to fluids with well-defined pressures and maximum heights, including loads due to water pressure during flood and surge.
$H$ = loads due to weight and lateral pressure of soil and water in soil
$L$ = $L_f$ + ($L_r$ or $P$)
$L_f$ = live loads due to intended use and occupancy, including loads due to movable objects and movable partitions and loads temporarily supported by the structure during maintenance. $L_f$ includes any permissible reduction. If resistance to impact loads is taken into account in design, such effects shall be included with the live loads $L_f$.
$L_r$ = roof live loads
$P$ = loads due to initial rainwater ponding
$R$ = seismic coefficient defined in Sec 2.5.3
$S$ = self-straining forces and effects arising from contraction or expansion resulting from temperature changes, shrinkage, moisture changes, creep in component materials, movement due to differential settlement, or combinations thereof.
$W$ = wind load
### 2.7.4 Combinations of Loads and Stress Increase for Allowable Stress Design Method
#### 2.7.4.1 Combination of Loads
Provisions of this section shall apply to all construction materials permitting their use in proportioning structural members by allowable stress design method. When this method is used in designing structural members, all loads listed herein shall be considered to act in the following combinations. The combination that produces the most unfavourable effect shall be used in design.
1. $D$
2. $D + L$
3. $D + S$
4. $D + (W \text{ or } E)$
5. $0.9D + (W \text{ or } E)$
6. $D + (H \text{ or } F)$
7. $D + L + (H \text{ or } F)$
8. $D + S + L$
9. $D + S + (W \text{ or } E)$
10. $D + L + (W \text{ or } E)$
11. $D + L + (H \text{ or } F) + (W \text{ or } E)$
12. $D + S + L + (H \text{ or } F) + (W \text{ or } E)$
#### 2.7.4.2 Stress Increase
Except as specified in Sec 1.5.5.(b) and elsewhere in this Code, the maximum permissible increase in the allowable stresses of all materials and soil bearing capacities specified in this Code for working (or allowable) stress design method, when load combinations (7) through (11) in Sec 2.7.4.1 above is used, shall be 33%.
### 2.7.5 Combinations of Loads for Strength Design Method
When strength design method is used, structural members and foundations shall be designed to have strength not less than that required to resist the most unfavorable effect of the combinations of factored loads listed in the following sections:
#### 2.7.5.1 Load Combinations for Reinforced Concrete and Masonry Structures
1. $1.4D$
2. $1.4D + 1.7L$
3. $1.4D + 1.4S$
4. $0.9D + 1.3(W \text{ or } 1.1E)$
5. $0.9D + 1.7(H \text{ or } F)$
6. $1.4D + 1.7L + 1.7(H \text{ or } F)$
7. $0.75[1.4D + 1.4S + 1.7L]$
8. $0.75[1.4D + 1.4S + 1.7(W \text{ or } 1.1E)]$
9. $0.75[1.4D + 1.7L + 1.7W]$
10. $0.75[1.4D + 1.7L + 1.7(H \text{ or } F) + 1.7(W \text{ or } 1.1E)]$
11. $0.75[1.4D + 1.4S + 1.7L + 1.7(H \text{ or } F) + 1.7(W \text{ or } 1.1E)]$
12. $1.4(D + L + E)$
When the structural effects of $F$, $H$, or $S$ are significant, their factored values shall be considered as $1.3F$, $1.6H$, and $1.2S$ and included with the above combinations to obtain the most unfavourable effect.
Also for buildings in Seismic Zone 3 and in Seismic Zone 2 having an Structural Importance Coefficient, $I$ greater than 1.0, the following additional load combinations shall be considered:
7. $1.2D + 0.5L + E'$
8. $0.9D + E'$
#### 2.7.5.2 Load Combinations for Steel Structures
1. $1.4D$
2. $1.2D + 1.6L_f + 0.5(L_r \text{ or } P)$
3. $1.2D + 1.6(L_r \text{ or } P) + (0.5L_f \text{ or } 0.8W)$
4. $1.2D + 1.3W + 0.5L_f + 0.5(L_r \text{ or } P)$
5. $1.2D + 1.5E + (0.5L_f)$
6. $0.9D + (1.3W \text{ or } 1.5E)$
**Exception:** The load factor on $L_f$ in combinations (3), (4) and (5) shall be equal to 1.0 for garages, areas occupied as places of public assembly, and all areas where the live load exceeds 5.0 kN/m².
#### 2.7.5.3 Load Combinations for Design using Other Materials
When structural members are designed using the strength design method and using a construction material not covered in Sec 2.7.5.1 and 2.7.5.2, any other code or standard having load combinations applicable for that construction material may be used provided that other requirements of Sec 2.7 are satisfied.
**Related Appendix**
Appendix A — Conversion of Expressions from SI to FPS Units
# Chapter 3: Foundation
Source: https://docs.sayed.app/bnbc2006/part-6-structural-design/chapter-3-foundation
## 3.1 SCOPE
The provisions of this chapter shall be applicable to the design and construction of foundations of buildings and structures for the safe support of dead and superimposed loads without exceeding the allowable stresses or design capabilities.
## 3.2 TERMINOLOGY
For terms used in this chapter, the following definitions shall apply.
**BATTER PILE:** The pile which is installed at an angle to the vertical. Also known as RAKER PILE.
**BEARING CAPACITY, SAFE:** The maximum intensity of loading that the soil will carry without risk of shear failure irrespective of any settlement that may occur.
**BEARING CAPACITY, ULTIMATE:** The intensity of loading at the base of a foundation which initiates shear failure of the supporting soil.
**BEARING PRESSURE, ALLOWABLE:** The maximum pressure that may be safely applied to a soil or rock by the foundation unit considered in design under expected loading and subsurface conditions.
**BEARING PRESSURE, DESIGN:** The pressure applied to a soil or rock by a foundation unit. It is equal to or smaller than the allowable bearing pressure.
**BEARING SURFACE:** The contact surface between a foundation unit and the soil or rock upon which it bears.
**BOULDER:** Cohesionless aggregates of angular, rounded or subrounded fragments of more or less unaltered rock or minerals, 50 per cent or more of which is larger than 200 mm in size.
**CAISSON:** A large, deep foundation unit other than a driven or bored pile that is sunk down to the ground to carry a structural unit, such as bridge abutment or pier.
**CLAY:** A natural aggregate of microscopic and submicroscopic mineral grains that are product of chemical decomposition and disintegration of rock constituents. It is plastic in moderate to wide range of water contents and the particle sizes are less than 2 μm.
**COBBLES:** Cohesionless aggregates of angular, rounded or subrounded fragments of more or less unaltered rock or minerals, 50 per cent or more of which is larger than 60 mm and smaller than 200 mm in size.
**DEEP FOUNDATION:** A foundation unit that provides support for a structure transferring loads either by end bearing to soil or rock at considerable depth below the structure, or by shaft resistance in the soil or rock in which it is placed; such as piles.
**DOWNDRAG:** The transfer of load (drag load) to a deep foundation unit by means of negative skin friction, when soil settles in relation to the unit.
**EXCAVATION:** The space created by the removal of soil or rock for the purpose of construction.
**FACTOR OF SAFETY:** The ratio of maximum available resistance to the resistance mobilized under the applied load.
**FILL:** Man made deposits of natural earth materials (soil, rock) and/or waste materials.
**FOOTING:** A shallow foundation constructed of masonry, concrete or other material under the base of a wall or one or more columns for the purpose of spreading the load over a larger area.
**FOUNDATIONS:** A system or arrangement of structural members through which the loads are transferred to supporting soil or rock.
**GRAVEL:** Cohesionless aggregates of angular, rounded or subrounded fragments of more or less unaltered rock or minerals, having 50 per cent or more of the particles larger than 4.75 mm and smaller than 60 mm in size.
**GROUND WATER:** That part of the subsurface water that is in the zone of saturation.
**GROUND WATER LEVEL:** The top surface of a free body of water in the ground. Also known as GROUND WATER TABLE.
**GROUND WATER TABLE:** See GROUND WATER LEVEL.
**LOAD, ALLOWABLE:** The maximum load that may be safely applied to a foundation unit under expected loading and soil conditions.
**LOAD, SERVICE:** The load actually applied to a foundation unit which is not greater than the allowable load.
**MAT FOUNDATION:** See RAFT.
**NEGATIVE SKIN FRICTION:** Soil resistance acting downward along the side of a deep foundation unit as a result of downdrag.
**OVERCONSOLIDATION RATIO (OCR):** The ratio between the preconsolidation pressure and the effective overburden stress.
**PIER:** A deep foundation unit with a large diameter to length ratio.
**PILE:** A slender deep foundation unit, made of materials such as steel, concrete, wood, or combination thereof, which is either premanufactured and placed by driving, jacking, jetting or screwing; or cast-in-place in a hole formed by driving, excavating or boring.
**PILE HEAD:** The upper part of a pile.
**PILE SHOE:** A separate reinforcement attached to the bottom end (pile toe) of a pile to facilitate driving, to protect the pile toe, and/or to improve the toe resistance of the pile.
**PILE TOE:** The bottom end of a pile.
**RAFT:** A spread foundation supporting an arrangement of column or walls in a regular or irregular layout transmitting the loads to the soil by means of a continuous slab, with or without depressions or openings. Also known as MAT FOUNDATION.
**RAKER PILE:** See BATTER PILE.
**ROCK:** A natural aggregate of one or more minerals that are connected by strong and permanent cohesive forces.
**SAND:** Cohesionless aggregates of rounded, subrounded, angular, subangular or flat fragments of more or less unaltered rock or minerals, 50 per cent or more of which is larger than 75 μm and smaller than 4.75 mm in size.
**SOIL:** A natural aggregate of mineral grains that can be separated by such gentle mechanical means as agitation in water.
**SHAFT RESISTANCE:** The resistance mobilized on the shaft (side) of a deep foundation. Upward resistance is called positive shaft resistance. Downward resistance is called negative shaft resistance (see negative skin friction).
**SHALLOW FOUNDATION:** A foundation unit that provides support for a structure by transferring loads to soil or rock at shallow depths. Usually, the depth to width ratio is less than unity and the depth is within 3 m from the surface. The load transfer is primarily through shear resistance of the bearing strata.
**SILT:** A fine grained soil with little or no plasticity. The particle size ranges from 75 μm to 2 μm.
**SPREAD FOUNDATION:** A shallow foundation which transmits the load to the ground by spreading it through one or more footings or a raft.
**TOTAL SETTLEMENT:** The total downward movement of the foundation unit under load.
## 3.3 SITE INVESTIGATION
### 3.3.1 Purpose
Application for construction of a new building or structure, and for the alteration of permanent structures which require changes in foundation loads and their distribution shall be accompanied by a statement describing the soil in the ultimate bearing strata, including sufficient records and data to establish its character, nature and load bearing capacity. Such records shall be certified by an engineer.
In areas which have already been developed, advantage may be taken of existing local knowledge, records of trial pits, boreholes, etc. in the vicinity, and the behaviour of existing structures, particularly those of a similar nature to those proposed. If the existing information is not sufficient or is inconclusive, the site shall be explored in detail, so as to obtain a knowledge of the type, uniformity, consistency, thickness, sequence and dip of strata and of ground water condition. Geological and agricultural soil maps of the area may give valuable information of site conditions. The local variation of general topography will often give some indication of the soil conditions and their variations. Records of earlier uses of soil in the vicinity shall be considered for assessing the foundation needs of the proposed new structure.
### 3.3.2 Methods of Exploration
Subsoil exploration process may be grouped into three types of activities such as: reconnaissance, exploration and detailed investigation. The reconnaissance method includes geophysical measurements, sounding or probing, while exploratory methods involve various drilling techniques. Some of the common exploration methods are described in Appendix B. The engineer shall approve an appropriate method of subsoil exploration and/or field test so as to reveal type, uniformity, consistency, thickness, sequence and dip of strata and ground water condition.
### 3.3.3 Number and Disposition of Trial Pits and Borings
The locations and spacing of sounding, pits and boreholes shall be such that the soil profiles obtained will permit a reasonably accurate estimate of the extent and character of the intervening soil or rock masses and will disclose important irregularities in subsurface conditions. For building structures, the following guidelines shall be followed:
a) For large areas covering industrial and residential colonies, the geological nature of the terrain will help in deciding the number of boreholes or trial pits. The whole area may be divided into grid pattern with Cone Penetration Tests (see Appendix B) performed at every 100 m grid points. The number of boreholes or trial pits shall be decided by examining the variation in penetration curves. At least 67% of the required number of borings or trial pits shall be located within the area under the building.
b) In compact building sites covering an area of 0.4 hectare (43,000 square feet), one borehole or trial pit in each corner and one in centre shall be adequate.
c) For widely spaced buildings covering an area of less than 90 m² (1000 square feet) and a height less than four storeys, one borehole or trial pit in the centre will suffice.
### 3.3.4 Depth of Exploration
The depth of exploration shall depend to some extent on the site and type of the proposed structure, and on certain design considerations such as safety against foundation failure, excessive settlement, seepage and earth pressure. Cognizance shall be taken of the character and sequence of the subsurface strata. The following guidelines shall be followed in determining the depth of exploration:
a) Normally the depth of exploration shall be one and a half times the estimated width or the least dimension of the footing below the foundation level. If the pressure bulbs for a number of loaded areas overlap, the whole area may be considered as loaded and exploration shall be carried down to one and a half times the least dimension. In weak soils, the exploration shall be continued to a depth at which the loads can be carried by the stratum in question without undesirable settlement or shear failure.
b) In case of pile foundation, the depth of exploration shall be equal to the width of the structure, subject to a maximum of 10 m beyond the tip of the pile.
c) Where rock is encountered in borings within the depth specified above, the rock is to be cored a minimum of 1.5 m, or further where necessary, to ensure a recovery of at least 35% from any 1.5 m penetration.
d) The depth, to which weathering process affects the deposit, shall be regarded as the minimum depth of exploration for a site. However, in no case shall this depth be less than 2 m, but where industrial processes affect the soil characteristics, this depth may be more.
## 3.4 CLASSIFICATION AND IDENTIFICATION OF SOILS
Soils shall be classified in accordance with Fig 6.3.1 and Table 6.3.1. The basic soil types are boulders, cobbles, gravel, sand, silt and clay, defined in terms of the particle size ranges shown in Table 6.3.2. Soils are divided into three major groups, coarse grained, fine grained and highly organic. The fine grained soils shall be classified using the plasticity chart shown in Fig 6.3.1. In addition to the classification given in Table 6.3.1, a soil shall be described by its colour, particle angularity (for coarse grained soils) and consistency. In addition to the above classification soils exhibiting swelling or collapsing characteristic shall be recorded. For swelling soils, the swelling pressure shall be established from oedometer test or linear shrinkage condition following available geotechnical correlation.
For undisturbed soils information on stratification, degree of compactness, cementation, moisture conditions and drainage characteristics shall be included.
![Fig 6.3.1: Plasticity Classification Chart (based on Materials Passing a 425 μm Sieve)]()
*Fig 6.3.1 Plasticity Classification Chart (based on Materials Passing a 425 μm Sieve)*
**Table 6.3.1 Classification of Soils**
| Classification (for particles smaller than 75 mm and based on estimated weights) | Symbol | Description | % finer than 0.075 mm | Other Criteria |
| :------------------------------------------------------------------------------------------------------------------------------------------- | :----: | :------------------------------------------------------------------------------------ | :-------------------: | :------------------------------------------------------------------------------------------------------------------------------------- |
| Coarse grained soils (over ½ of the material larger than 0.075 mm) — Gravels (over ½ of coarse fraction larger than 4.75 mm) — Clean gravels | GW | Well graded gravels, sandy gravels, sand gravel mixture, little or no fines. | \<5 | $C_u \geq 4$ and $1 \leq C_C \leq 3$ |
| " | GP | Poorly graded gravels, sandy gravels, sand gravel mixture, little or no fines | \<5 | $C_u < 4$ and $1 > C_C > 3$ |
| Gravel with fines | GM | Silty gravels, silty sandy gravels | >12 | $I_p<4$ or the limit values below 'A' line of plasticity chart; for $4>I_p>7$ and limit values above 'A' line, dual symbol required\* |
| " | GC | Clayey gravels, silty clayey gravels | >12 | $I_p>7$ and the limit values above 'A' line of Plasticity Chart |
| Sands (over ½ of coarse fraction smaller than 4.75 mm) — Clean Sands | SW | Well graded sand, gravelly sand, little or no fines | \<5 | $C_u \geq 6$ and $1 \leq C_C \leq 3$ |
| " | SP | Poorly graded sands, gravelly sand, little or no fines | \<5 | $C_u < 6$ and $1 > C_C > 3$ |
| Sands with fines | SM | Silty sand, poorly graded sand silt mixtures | >12 | $I_p<4$ or the limit values below 'A' line of plasticity chart; for $4>I_p>7$ and limit values above 'A' line, dual symbols required\* |
| " | SC | Clayey sand, sand clay mixtures. | >12 | $I_p>7$ and the limit values above 'A' line of plasticity chart |
| Fine grained soils (over ½ of the material smaller than 0.075 mm) — Silts & Clays $w_L < 35$ | ML | Low plastic silt, very fine sands, rock flour, silt with sand | — | Limit values below 'A' line of plasticity chart & $I_p<4$ |
| " | CL | Clays of low plasticity, gravelly clay, sandy clay, silty clay, lean clay | — | Limit values above 'A' line of plasticity chart and/or $I_p>7$ |
| " | OL | Organic silt and clay of low plasticity | — | $\dfrac{\text{Liquid limit (oven dried)}}{\text{Liquid limit (undried)}} < 0.75$ |
| Silts & Clays $3550$ | MH | High plastic silt, micaceous fine sandy or silty soil, elastic silt | — | Limit values on or below 'A' line of plasticity chart |
| " | CH | High plastic clay, fat clay | — | Limit values above 'A' line of plasticity chart |
| " | OH | Organic clay of high plasticity | — | $\dfrac{\text{Liquid limit (oven dried)}}{\text{Liquid limit (undried)}} < 0.75$ |
| Soils of high organic origin | Pt | Peat and highly organic soils | — | Identified by colour, odour, fibrous texture and spongy characteristics |
Note: \* For example, GC-GM, silty, clayey gravel with sand.
$C_u = D_{60}/D_{10}$ = Uniformity Coefficient, $C_C = D_{30}^2/(D_{60} \times D_{10})$ = Coefficient of Curvature
Table 6.3.1's layout in the source (page 6-75) uses merged rows and side-braces to group related classes (e.g. GW/GP under "clean gravels", GM/GC under "gravel with fines") rather than repeating the group label in each row. This has been flattened into a per-row Markdown table, restating the applicable group description in the first data row of each group (marked `"` for repeated groups) to preserve the same information without rowspans, which Markdown tables cannot represent.
**Table 6.3.2 Particle Size Ranges**
| Soil Type | Particle Size Range, mm |
| :------------- | :---------------------: |
| Boulders | >200 |
| Cobbles | 60 - 200 |
| Gravel: Coarse | 20 - 60 |
| Gravel: Medium | 10 - 20 |
| Gravel: Fine | 4.75 - 10 |
| Sand: Coarse | 0.6 - 4.75 |
| Sand: Medium | 0.2 - 0.6 |
| Sand: Fine | 0.075 - 0.2 |
| Silt | 0.002 - 0.075 |
| Clay | \<0.002 |
## 3.5 MATERIALS
All materials for the construction of foundations shall conform to the requirements of Part 5.
### 3.5.1 Concrete
All concrete materials and steel reinforcement used in foundations shall conform to the requirements specified in Chapters 5 and 8 unless otherwise specified in this section.
Concrete to be used in bored or driven cast-in-situ piles shall have a strength greater than 20 MPa and a minimum cement content of 400 kg/m³. For such piles not exceeding a depth of 6 m, where underwater concreting is not involved and where soil conditions are favourable and nonaggressive, the concrete strength may be 15 MPa with a minimum cement content of 350 kg/m³, provided that a higher strength concrete is not needed from structural considerations.
### 3.5.2 Timber
Timber used in foundation shall conform to the standards specif