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# 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

Symbol Meaning
Section
ABM
Cross-sectional area of the base metal,  mm2
10.10.2.4


Nominal unthreaded body area of bolt or threaded part,  mm2
10.10.3.6


Cross-sectional area of a horizontal boundary element (HBE),
mm2
10.20.17.2.1


Cross-sectional area of the overlapping branch,  mm2
10.11.2.3


Cross-sectional area of the overlapped branch,  mm2
10.11.2.3


Cross-sectional area of a vertical boundary element
(VBE),mm2
10.20.17.2.1


Area of an upset rod based on the major thread diameter,  mm2 Table 6.10.10


Effective net area,  mm2
10.4.2


Summation of the effective areas of the cross section based on
the reduced effective width, 	, mm2
10.5.7.2


Flange area, mm2
10.20.8


Area of compression flange
10.7.3.1



Gross tension flange area,  mm2
10.6.13.1


Net tension flange area,  mm2
10.6.13.1


Area of tension flange,  mm2
10.7.3.1



Gross area of member,  mm2
10.2.3.13



Gross area of section based on design wall thickness,  mm2
10.7.6



Chord gross area,  mm2
10.11.2.2



Gross area,  mm2
10.20.9



Gross area subject to shear,  mm2
10.10.4.3


Net area of member,  mm2
10.2.3.13


Net area subject to tension,  mm2
10.10.4.3



Net area subject to shear,  mm2
10.10.4.2

Symbol Meaning
Section


Projected bearing area,  mm2
10.10.7


Area of the yielding segment of steel core, mm2
10.20.16


Shear area on the failure path,  mm2
10.4.5.1


Stiffener area,  mm2
10.7.3.3


Area of link stiffener, mm2
10.20.15


Net tensile area,  mm2
10.17.4


Web area, the overall depth times the web thickness, ,
mm2
10.7.2.1


Effective area of the weld, mm2
10.10.2.4


Link web area, mm2
10.20.15


Effective area of weld throat of any th weld element, mm2
10.10.2.4


Area of steel concentrically bearing on a concrete support, mm2
10.10.8


Maximum area of the portion of the supporting surface that is
geometrically similar to and concentric with the loaded area,
mm2.
10.10.8

Factor for lateral-torsional buckling in tees and double angles
10.6.9.2

Overall width of rectangular HSS member, measured 90o to the
plane of connection, mm.
10.11.1.1,
Table 6.10.2

Overall width of rectangular HSS main member, measured 90o
to the plane of the connection,mm.
10.11.2.1,
10.11.3.1

Overall width of rectangular HSS branch member, measured
90o to the plane of the connection, mm.
10.11.2.1,
10.11.3.1

Overall branch width of the overlapping branch
10.11.2.3

Overall branch width of the overlapped branch
10.11.2.3

Width of plate, measure 90o to the plane of the connection, mm.
10.11.1.1

Width of plate, transverse to the axis of the main member,mm.
10.11.2.3

Symbol Meaning
Section
,
Factors used in determining  for combined bending and
axial forces when first-order analysis is employed
10.3.2.1

HSS torsional constant
10.8.3.1

Ratio of required strength to available strength
Table 6.10.8

Lateral-torsional buckling modification factor for nonuniform
moment diagrams when both ends of the unsupported segment
are braced
10.6.1

Coefficient relating relative brace stiffness and curvature
10.19.3.1,
10.20.9

Deflection amplification factor
P.2

Constant based on stress category, given in Table 6.10.14
10.17.3

Coefficient assuming no lateral translation of the frame
10.3.2.1

Ponding flexibility coefficient for primary member in a flat roof
10.16.1

Coefficient for web sidesway buckling
10.10.10.4

Parameter used for determining the approximate fundamental
period
P.2

Ponding flexibility coefficient for secondary member in a flat
roof
10.16.1


Web shear coefficient
10.7.2.1

Warping constant,  mm6
10.5.4

Nominal dead load
10.16.2

Dead load due to the weight of the structural elements and
permanent features on the building, N.
10.20.9

Outside diameter of round HSS, mm.
Table 6.10.8

Outside diameter of round HSS member, mm.
Table 6.10.1

Outside diameter of round HSS member, mm.
10.11.1.1

Outside diameter of round HSS main member, mm.
10.11.2.1

Outside diameter of round HSS main member, mm.
10.11.3.1

Outside diameter, mm.
10.5.7.2

Symbol Meaning
Section

Chord diameter, mm.
10.11.2.2

Outside diameter of round HSS branch member,mm.
10.11.2.1

Outside diameter of round HSS branch member,mm.
10.11.3.1

Factor used in Eq. 6.10.144, dependent on the type of
transverse stiffeners used in a plate girder
10.7.3.3

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

Eccentricity in a truss connection, positive being away from
the branches, mm.
10.11.2.1

Modulus of elasticity of steel = 200000 MPa
Table 6.10.1

Modulus of elasticity of concrete, MPa.
10.18.2.3

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

Modulus of elasticity of steel at elevated temperature, MPa.
10.18.2.3

Available axial stress at the point of consideration, MPa.
10.8.2
!"
Nominal strength of the base metal per unit area, MPa.
10.10.2.4
!#
Available flexural stress at the point of consideration about the
major axis, MPa.
10.8.2
\$
Available flexural stress at the point of consideration about the
minor axis, MPa.
10.8.2

Available stress, MPa.
10.11.2.2

Critical stress, MPa.
10.5.3

Buckling stress for the section as determined by analysis, MPa.
10.6.12.2

Symbol Meaning
Section
%
Critical stress about the minor axis, MPa.
10.5.4
$
Critical torsional buckling stress, MPa.
10.5.4

Elastic critical buckling stress, MPa.
10.3.1.3
&
Elastic flexural buckling stress about the major axis, MPa.
10.5.4
'((
Electrode classification number, MPa.
10.10.2.4
%
Elastic flexural buckling stress about the minor axis, MPa.
10.5.4
$
Elastic torsional buckling stress, MPa.
10.5.4
)
A calculated stress used in the calculation of nominal flexural
strength, MPa.
Table 6.10.1

Nominal torsional strength
10.8.3.3

Nominal tensile stress , or shear stress,
, from Table
6.10.10,  MPa.
10.10.3.6

Nominal tensile stress from Table 6.10.10, MPa.
10.10.3.7

*

Nominal tensile stress modified to include the effects of
shearing stress, MPa.
10.10.3.7

Nominal shear stress from Table 6.10.10, MPa.
10.10.3.7
+,
Design stress range, MPa.
10.17.3
-.
Threshold fatigue stress range, maximum stress range for
indefinite design life from Table 6.10.14, MPa.
10.17.1

Specified minimum tensile strength of the type of steel being
used, MPa.
10.4.2

Specified minimum tensile strength of the connected material,
MPa.
10.10.3.10

Specified minimum tensile strength of HSS material, MPa.
10.11.1.1

Specified minimum tensile strength of HSS material, MPa.
10.11.2.1

Ultimate strength of HSS member, MPa.
10.11.3.1

Symbol Meaning
Section

Specified minimum tensile strength, MPa.
10.20.6

Specified minimum tensile strength of the type of steel being
used at elevated temperature, MPa.
10.18.2

Nominal strength of the weld metal per unit area, MPa.
10.10.2.4

Nominal stress in any / weld element, MPa.
10.10.2.4
&
x component of stress  , MPa.
10.10.2.4
%
y component of stress Fwi,  MPa.
10.10.2.4
%
Specified minimum yield stress of the type of steel being
ঁংবফ, গচধ. অং ঁংবফ রহ:যরং ঝঢ়বপরভরপধঃরড়হ, ুুরবষফ ংঃৎবংংচ্
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
10.20.6,
Table 6.10.1
%
Specified minimum yield stress of the compression flange, MPa.
10.15.3
%
Specified minimum yield stress of the column web, MPa.
10.10.10.6
%
Specified minimum yield stress of HSS member material, MPa.
10.11.1.1
%
Specified minimum yield stress of HSS main member material,
MPa.
10.11.2.1
%
Specified minimum yield stress of HSS main member, MPa.
10.11.3.1
%
Specified minimum yield stress of HSS branch member
material, MPa.
10.11.2.1
%
Specified minimum yield stress of HSS branch member, MPa.
10.11.3.1
%
% of a beam, MPa.
10.20.9
%
% of a column, MPa.
10.20.9
%
Specified minimum yield stress of the overlapping branch
material, MPa.
10.11.2.3
%
Specified minimum yield stress of the flange, MPa.
10.10.10.1
%
Specified minimum yield stress of the type of steel used at
elevated temperature, MPa.
10.18.2
%
Specified minimum yield stress of plate, MPa.
10.11.1.1

Symbol Meaning
Section
%
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
%
Specified minimum yield stress of the stiffener material, MPa.
10.7.3.3
%
Specified minimum yield stress of the web, MPa.
10.10.10.2
Shear modulus of elasticity of steel = 77 200 MPa.
10.5.4
Gap between toes of branch members in a gapped K-
connection, neglecting welds, mm.
10.11.2.1
Flexural constant
10.5.4
Overall height of rectangular HSS member, measured in the
plane of connection, mm.
10.11.1.1
Overall height of rectangular HSS main member, measured in
plane of connection, mm.
10.11.2.1
Overall height of rectangular HSS main member, measured in
plane of connection, mm.
10.11.3.1
Overall height of rectangular HSS member, measured in the
plane of connection, mm.
Table 6.10.2
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 =
3/, where, 3 = 2/678
10.11.2.1
Height of story, which may be taken as the distance between
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
10.20.8
2
Overall height of rectangular HSS branch member, measured
in the plane of the connection, mm.
10.11.3.1
2
Overall height of rectangular HSS branch member, measured
in the plane of the connection, mm.
10.11.2.1
2
Overall depth of the overlapping branch
10.11.2.3
Σ2
Story shear produced by the lateral forces used to compute ∆H,
N.
10.3.2.1
:
Moment of inertia in the place of bending, mm4.
10.3.2.1

Symbol Meaning
Section
:
Moment of inertia about the axis of bending, mm4.
10.14.3
:
Moment of inertia, mm4
10.20.12
:
Moment of inertia of a vertical boundary element (VBE) taken
perpendicular to the direction of the web plate line, mm4
10.20.17
:
Moment of inertia of the steel deck supported on secondary
members, mm4
10.16.1
:
Moment of inertia of primary members, mm4
10.16.1
:
Moment of inertia of secondary members, mm4
10.16.1
:&
, :%
Moment of inertia about the principal axes, mm4
10.5.4
:%
Out-of-plane moment of inertia, mm4
10.19.2
:$
Minor principal axis moment of inertia, mm4
10.6.10.2
:%
Moment of inertia about y-axis referred to the compression
flange, or if reverse curvature bending referred to smaller
flange, mm4
10.6.1
;
Torsional constant, mm4
10.5.4
<
Effective length factor determined in accordance with Sec 10.3
10.3.1.2
<
Effective length factor for prismatic member
10.20.13
<$
Effective length factor for torsional buckling
10.5.4
\<
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
\<
Effective length factor in the plane of bending, calculated based
on a sidesway buckling analysis
10.3.2.1
========

Story height, mm.
10.3.2.1
========

Laterally unbraced length of a member, mm.
10.5.2
======

Length of member between work points at truss chord
centerlines,mm.
10.5.5

Symbol Meaning
Section
=======

Length of the member, mm.
10.8.3
======

Actual length of end-loaded weld, mm.
10.10.2.2
=========

Nominal occupancy live load
10.18.1.4
=========

Span length, mm.
10.19.2
=======

Span length of the truss, mm.
10.20.12
========

Distance between VBE centerlines, mm
10.20.17
\=
Distance between braces, mm.
10.19.2
\=
Length between points that are either braced against lateral
displacement of compression flange or braced against twist of
the cross section, mm.
10.6.2,
10.20.13
\=
Distance between plastic hinge locations, mm
10.20.9
\=
Clear distance, in the direction of the force, between the edge
of the hole and the edge of the adjacent hole or edge of the
material,mm.
10.10.3.10
\=
Link length, mm
10.20.15
\=
Clear distance between VBE flanges, mm
10.20.17
\=
Total effective weld length of groove and fillet welds to
rectangular HSS,mm.
10.11.2.3
\=
Limiting laterally unbraced length for the limit state of
yielding, mm.
10.6.2.2
\=
Column spacing in direction of girder, m
10.16
\=
Limiting laterally unbraced length for full plastic flexural
strength, uniform moment case,mm.
10.20.12
\=
Limiting laterally unbraced length for plastic analysis, mm.
10.15.7
\=
Limiting laterally unbraced length for plastic analysis, mm
10.20.13
\=>
Maximum unbraced length for(the required flexural
strength),mm.
10.19.2
=======

Limiting laterally unbraced length for limit state of inelastic
lateral-torsional buckling, mm.
10.6.2.2

Symbol Meaning
Section
\=
Column spacing perpendicular to direction of girder, m
10.16.1
\=
Length of the special segment, mm
10.20.12
========

Distance from maximum to zero shear force,mm.
10.7.6
?
Absolute value of moment at quarter point of the unbraced
segment, N-mm.
10.6.1

Required flexural strength in chord, using ASD load
combinations, N-mm.
10.11.2.2

Required flexural strength, using ASD load combinations,
N-mm.
10.20.9


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
!
Absolute value of moment at centerline of the unbraced
segment, N-mm.
10.6.1

Required bracing moment,N-mm.
10.19.2
@
Absolute value of moment at three-quarter point of unbraced
segment, N-mm.
10.6.1
@(&,%) Available flexural strength determined in accordance with Sec
10.6,N-mm.
10.8.1.1
@&
Available flexural-torsional strength for strong axis flexure
determined in accordance with Sec 10.6,N-mm.
10.8.1.3

Elastic lateral-torsional buckling moment, N-mm.
10.6.10.2
D
First-order moment under LRFD or ASD load combinations
caused by lateral translation of the frame only, N-mm.
10.3.2.1
&
Absolute value of maximum moment in the unbraced
segment,N-mm.
10.6.1

Nominal flexural strength, N-mm.
10.6.1

Nominal flexural strength, N-mm.
10.20.11

Nominal flexural strength of the chord member of special
segment, N-mm.
10.20.12

First-order moment using LRFD or ASD load combinations
assuming there is no lateral translation of the frame, N-mm.
10.3.2.1

Symbol Meaning
Section

Plastic bending moment,N-mm.
Table 6.10.1

Nominal plastic flexural strength, N-mm.
Table 6.10.8

Nominal plastic flexural strength modified by axial load, N-
mm.
10.20.15

Nominal plastic flexural strength of the beam, N-mm.
10.20.9

Nominal plastic flexural strength of the column, N-mm.
10.20.8
,& Expected plastic moment, N-mm.
10.20.9

Required second-order flexural strength under LRFD or ASD
load combinations, N-mm.
10.3.2.1

Required flexural strength using LRFD or ASD load
combinations,N-mm.
10.8.1

Required flexural strength in chord, N-mm.
10.11.2.2

Expected flexural strength, N-mm.
10.20.9
E Required in-plane flexural strength in branch,N-mm.
10.11.3.2
EF Required out-of-plane flexural strength in branch,N-mm.
10.11.3.2

Required flexural strength, using LRFD load combinations, N-
mm.
10.20.9

Required flexural strength in chord, using LRFD load
combinations,N-mm.
10.11.2.2


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
,& Expected required flexural strength, N-mm.
10.20.15
%
Yield moment about the axis of bending,  N-mm.
Table 6.10.1

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

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

Symbol Meaning
Section
Length of bearing (not less than k for end beam reactions),mm.
10.10.10.2
Bearing length of the load, measured parallel to the axis of the
HSS member, (or measured across the width of the HSS in the
case of the loaded cap plates), mm.
10.11.1.1
Number of stress range fluctuations in design life
10.17.3
3
Number of bolts carrying the Applied tension
10.10.3.9
3
Additional lateral load
10.3.2.2
3
Notional lateral load Applied at level , N.
10.14.3
3
Number of slip planes
10.10.3.8
G

Overlap connection coefficient
10.11.2.2
H
Pitch,  mm per thread
10.17.4
H
Required axial strength of a column using ASD load
combinations, N.
10.20.8
H
Required compressive strength using ASD load combinations,
N.
10.20.9
H
Required strength of lateral brace at ends of the link, N.
10.20.15
H
Required brace strength, N.
10.19.2
H
Available axial compressive strength, N.
10.8.1.1
H
Available tensile strength, N.
10.8.1.2
H
Available axial strength of a column, N.
10.20.9
HF
Available compressive strength out of the plane of bending, N.
10.8.1.3
H,H
Elastic critical buckling load for braced and unbraced frame,
respectively, N.
10.3.2.1
H)
Euler buckling load, evaluated in the plane of bending, N.
10.14.3

Symbol Meaning
Section
HD(,)
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
H(,)
First-order axial force using LRFD or ASD load combinations,
assuming there is no lateral translation of the frame (tension or
compression, N.
10.3.2.1
H
Nominal axial strength, N.
10.4.2
H
Nominal axial strength of a column, N.
10.20.8
H
Nominal axial compressive strength of diagonal members of
the special segment, N.
10.20.12
H
Nominal axial tensile strength of diagonal members of special
segment, N.
10.20.12
H
Required compressive strength using ASD or LRFD load
combinations, N.
10.20.9
H
Required second-order axial strength using LRFD or ASD load
combinations, N.
10.3.2.1
H
Required axial compressive strength using LRFD or ASD load
combinations, N.
10.3.2.2
H
Required tensile strength using LRFD or ASD load
combinations, N.
10.8.1.2
H
Required strength, N.
10.10.10.6
H
Required axial strength in chord, N.
10.11.2.2
H
Required axial strength in branch, N.
10.11.3.2
H
Required compressive strength, N.
10.20.15
H
Required axial strength in compression, N.
10.15.4
H
Required axial strength of a column or a link in LRFD load
combinations, N.
10.20.8
H
Required
compressive
strength
using
LRFD
load
combinations, N.
10.20.9
H%
Member yield strength, N.
10.3.2.2
H%
Nominal axial yield strength of a member, equal to  %

,N.
Table 6.10.8

Symbol Meaning
Section
H%
Axial yield strength of steel core, N.
10.20.16
I
Full reduction factor for slender compression elements
10.5.7
I
Reduction factor for slender stiffened compression elements
10.5.7.2
I
Maximum unbalanced vertical load effect applied to a beam by
the braces, N.
10.20.13
I
Axial forces and moments generated by at least 1.25 times the
expected nominal shear strength of the link
10.20.15
I
Chord-stress interaction parameter
10.11.2.2
I
Reduction factor for slender unstiffened compression elements
10.5.7.1
R
Seismic response modification coefficient
10.20.1
J
Seismic response modification coefficient
10.1.1.1
J
Nominal load due to rainwater or snow, exclusive of the
ponding contribution, MPa.
10.16.2
J
Required strength (ASD)
10.2.3.4
JKL)
Reduction factor for joints using a pair of transverse fillet welds
only
10.17.3
J
Factor in Eq. 6.10.8 dependent on type of system
10.3.2.1
J
Cross-section monosymmetry parameter
10.6.1
J
Nominal strength, N.
10.2.3.3
J
Nominal strength, N.
10.20.6
J
Nominal slip resistance, N.
10.10.3.8
J
Web plastification factor
10.6.4.1
JMNM
Reduction factor for reinforced or unreinforced transverse
partial-joint-penetration (PJP) groove welds
10.17.3
J
Web plastification factor corresponding to the tension flange
yielding limit state
10.6.4.4

Symbol Meaning
Section
J
Ratio of the expected tensile strength to the specified minimum
tensile strength  , as related to overstrength in material yield
stress J%
10.20.6
J
Required strength (LRFD)
10.2.3.3
J
Required strength
10.20.9
J

Panel zone nominal shear strength
10.20.9
JD
Total nominal strength of longitudinally loaded fillet welds, as
determined in accordance with Table 6.10.8
10.10.2.4
J
Total nominal strength of transversely loaded fillet welds, as
determined in accordance with Table 6.10.8 without the
alternate in Sec 10.10.2.4 (a)
10.10.2.4
J%
Ratio of the expected yield stress to the specified minimum
yield stress,  %
10.20.6
O
Elastic section modulus of round HSS,  mm3
10.6.8.2
O
Lowest elastic section modulus relative to the axis of bending,
mm3
10.6.12
O
Chord elastic section modulus, mm3
10.11.2.2
O
Spacing of secondary members,  m
10.16.1
O
Elastic section modulus to toe in compression relative to axis
of bending, mm3.
10.6.10.3
O
Effective section modulus about major axis, mm3
10.6.7.2
O&, O&
Elastic section modulus referred tension and compression
flanges, respectively,  mm3
Table 6.10.1
O&, O% Elastic section modulus taken about the principal axes, mm3
10.6.2.2, F6
O%
For channels, taken as the minimum section modulus
10.6.6
P
Nominal forces and deformations due to design-basis fire
defined in Sec 4.2.1
10.18.1.4
P
Tension force due to ASD load combinations, kN.
10.10.3.9

Symbol Meaning
Section
P
Minimum fastener tension given in Table 6.10.9, kN.
10.10.3.8
P
Available torsional strength, N-mm.
10.8.3.2
P
Nominal torsional strength, N-mm.
10.8.3.1
P
Required torsional strength, N-mm.
10.8.3.2
P
Tension force due to LRFD load combinations, kN.
10.10.3.9
Q
Shear lag factor
10.4.3.3
Q
Utilization ratio
10.11.2.2
Q
Reduction coefficient, used in calculating block shear rupture
strength
10.10.4.3
Q
Stress index
10.16.2
Q
Stress index
10.16.2
R
Required shear strength using ASD load combinations, N.
10.20.9
R
Available shear strength, N.
10.7.3.3
R
Nominal shear strength, N.
10.7.1
R
Nominal shear strength of a member, N.
10.20.15
R
Nominal shear strength of an active link, N.
Table 6.10.8
R
Nominal shear strength of an active link modified by axial load
magnitude, N.
10.20.15
R
Expected vertical shear strength of the special segment, N.
10.20.12
R
Required shear strength at the location of the stiffener, N.
10.7.3.3
R
Required shear strength using LRFD or ASD load
combinations, N.
10.8.3.2
R
Required shear strength using LRFD load combinations, N.
10.20.10
S
Gravity load from the LRFD load combination or 1.6 times
the ASD load combination Applied at level , N.
10.3.2.2
S
Hole reduction coefficient, N.
10.6.13.1

Symbol Meaning
Section
T
Plastic section modulus about the axis of bending,  mm3
10.6.7.1
Z
Plastic section modulus of a member, mm3.
10.20.9
T
Branch plastic section modulus about the correct axis of
bending,  mm3
10.11.3.3
T
Plastic section modulus of the beam, mm3.
10.20.9
T
Plastic section modulus of the column, mm3.
10.20.9
T&
Plastic section modulus x-axis, mm3.
10.20.8
T,!+
Minimum plastic section modulus at the reduced beam section,
mm3.
10.20.9
T&,%
Plastic section modulus about the principal axes,  mm3
10.6.2, F6.1
U
Shortest distance from edge of pin hole to edge of member
measured parallel to direction of force, mm.
10.4.5.1
U
Distance between connectors in a built-up member, mm.
10.5.6.1
U
Clear distance between transverse stiffeners,mm.
10.6.13.2
U
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
U
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

Width of unstiffened compression element; for flanges of
I-shaped members and tees, the width 	 is half the full-flange
width, 	; for legs of angles and flanges of channels and zees,
the width 	 is the full nominal dimension; for plates, the width
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 	 is the clear
distance between the webs less the inside corner radius on each
side, mm.
10.2.4.1,
10.2.4.2

Symbol Meaning
Section

Full width of longest angle leg, mm.
10.5.7.1

Outside width of leg in compression, mm.
10.6.10.3

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

Width of column flange, mm.
10.10.10.6

Width of column flange, mm.
10.20.9

Reduced effective width,mm.
10.5.7.2

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
F
Effective width of the branch face welded to the chord
10.11.2.3
F

Effective width of the branch face welded to the overlapped
brace.
10.11.2.3

Flange width, mm.
10.2.4.1

Flange width, mm.
10.20.9

Compression flange width, mm.
10.6.4.2

Width of tension flange, mm.
10.7.3.1
D
Longer leg of angle, mm.
10.5.5

Shorter leg of angle, mm.
10.5.5

Stiffener width for one-sided stiffeners, mm.
10.19.2

Full nominal depth of section, mm.
10.2.4.1

Pin diameter,mm.
10.4.5.1

Full nominal depth of tee, mm.
10.5.7.1

Depth of rectangular bar, mm.
10.6.11.2

Symbol Meaning
Section

Nominal fastener diameter, mm.
10.10.3.3

Diameter, mm.
10.10.7

Roller diameter,mm.
10.10.7
d
Nominal fastener diameter, mm.
10.20.7
d
Overall beam depth, mm.
10.20.15

Beam depth,mm.
10.10.10.6

Nominal diameter (body or shank diameter), mm.
10.17.4

Column depth, mm.
10.10.10.6

Overall column depth, mm.
10.20.9
$
Overall panel zone depth between continuity plates, mm.
10.20.9
V
Eccentricity in a truss connection, positive being away from
thebranches, mm.
10.11.2.1
e
EBF link length, mm.
10.20.15
W
Required axial stress at point of consideration of LRFD or ASD
load combinations, MPa.
10.8.2
W(,$)
Required flexural stress at the point of consideration (major
axis, minor axis) using LRFD or ASD load combinations, MPa.
10.8.2
W
\*
Specified minimum compressive strength of concrete at
elevated temperatures, MPa.
10.18.2
WF
Stress due to D + R (the nominal dead load + the nominal load
due to rainwater or snow exclusive of the ponding contribution,
MPa.
10.16.2
W

Required shear strength per unit area, MPa.
10.10.3.7
X
Transverse center-to-center spacing (gage) between fastener
gage lines, mm.
10.2.3.13
X
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

Symbol Meaning
Section
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
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
ℎF
Distance between flange centroids, mm.
10.6.2.2
ℎF
Distance between flange centroids, mm
10.20.9
ℎ
Twice the distance from plastic neutral axis to the nearest line
of fasteners at the compression flange or inside face of
compression flange when welds are used, mm
10.2.4.2
ℎ
Hole factor
10.10.3.8
Z
Factor defined by Eq. 6.10.141 for minimum moment of inertia
for a transverse stiffener
10.7.2.2
\[
Distance from outer face of flange to the web toe of fillet, mm.
10.10.10.2
\[
Outside corner radius of HSS, which is permitted to be taken as
1.5t if unknown, mm.
10.11.1.3
\[
Coefficient for slender unstiffened elements, mm.
Table 6.10.1
\[
Slip-critical combined tension and shear coefficient
10.10.3.9
\[

Web plate buckling coefficient
10.7.2.1
\
Largest laterally unbraced length along either flange at the point
of load, mm.
10.10.10.4
\
Length of bearing,mm.
10.10.7
\
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

Symbol Meaning
Section
Number of nodal braced points within the span
10.19.2
Threads per mm.
10.17.4
]
Ratio of element i deformation to its deformation at maximum
stress
10.10.2.4
]
Projected length of the overlapping branch on the chord
10.11.2.2
^
Overlap length measured along the connecting face of the chord
beneath the two branches
10.11.2.2
\_
Governing radius of gyration, mm.
10.5.2
r
Governing radius of gyration, mm.
10.20.13
\_
Distance from instantaneous center of rotation to weld
element with minimum\`a
b ratio, mm.
10.10.2.4
\_
Minimum radius of gyration of individual component in a built-
up member, mm.
10.5.6.1
\_
Radius of gyration of individual component relative to its
centroidal axis parallel to member axis of buckling, mm.
10.5.6.1
\_Fc
Polar radius of gyration about the shear center,mm.
10.5.4
\_
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
\_
Effective radius of gyration used in the determination of =for
the lateral-torsional buckling limit state for major axis bending
of doubly symmetric compact I-shaped members and channels
10.6.2.2
\_&
Radius of gyration about geometric axis parallel to connected
leg, mm.
10.5.5
\_%
Radius of gyration about y-axis, mm.
10.5.4
\_%
Radius of gyration about y-axis, mm.
10.20.9
\_\$
Radius of gyration for the minor principal axis, mm.
10.5.5

Symbol Meaning
Section
Longitudinal center-to-center spacing (pitch) of any two
consecutive holes, mm.
10.2.3.13

Thickness of element, mm.
10.2.4.2
t
Thickness of element, mm.
Table 6.10.8

Wall thickness, mm.
10.5.7.2

Angle leg thickness, mm.
10.6.10.2

Width of rectangular bar parallel to axis of bending, mm.
10.6.11.2

Thickness of connected material, mm.
10.10.3.10

Thickness of plate, mm.
10.4.5.1

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

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

Design wall thickness of HSS main member, mm.
10.11.3.1

Design wall thickness of HSS main member, mm.
10.11.2.1

Design wall thickness of HSS member, mm.
10.11.1.1

Design wall thickness of HSS branch member,  mm.
10.11.2.1

Design wall thickness of HSS branch member,  mm.
10.11.3.1

Thickness of beam flange, mm.
10.20.9

Thickness of the overlapped branch,mm.
10.11.2.3

Thickness of the column flange,mm.
10.10.10.6

Symbol Meaning
Section

Thickness of column flange, mm.
10.20.9

Thickness of the loaded flange, mm.
10.10.10.1

Thickness of flange, mm.
10.20.17

Compression flange thickness, mm.
10.6.4.2

Thickness of plate, mm.
10.11.1.1

Thickness of the attached transverse plate, mm.
10.11.2.3

Thickness of tension loaded plate, mm.
10.17.3

Thickness of panel zone including doubler plates, mm.
10.20.9

Web stiffener thickness, mm.
10.19.2

Web thickness, mm.
Table 6.10.1

Thickness of web, mm.
Table6.10.8

Thickness of element, mm.
10.5.7.1

Column web thickness, mm.
10.10.10.6

Beam web thickness, mm.
10.19.3
d
Width of cover plate, mm.
10.6.13.3
d
Weld leg size, mm.
10.10.2.2
d
Plate width, mm.
Table 6.10.2
d
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
d\$
Width of panel zone between column flanges, mm.
10.20.9
x
Parameter used for determining the approximate fundamental
period
Appendix P.2
eF,fF
Coordinates of the shear center with respect to the centroid,
mm.
10.5.4

Symbol Meaning
Section
e̅
Connection eccentricity,mm.
Table 6.10.2
f
Subscript relating symbol to weak axis
h
Subscript relating symbol to minor principal axis bending
T
Minimum plastic section modulus at the reduced beam section,
mm3
10.20.9
i
Factor used in Eq. 6.10.2.2
10.3.2.1
i
Separation ratio for built-up compression members =ℎ(2\_)
⁄
10.5.6.1
α
Angle of diagonal members with the horizontal
10.20.12
α
Angle of web yielding in radians, as measured relative to the
vertical
10.20.17
m
Reduction factor given by Eq. 6.10.159
10.10.2.2
m
The width ratio; the ratio of branch diameter to chord diameter
\= / for round HSS; the ratio of overall branch width to
chord width = / for rectangular HSS
10.11.2.1,
10.11.3.1
m
Compression strength adjustment factor
10.20.16
m-
Brace stiffness requirement excluding web distortion,
N-mm/radian.
10.19.2
m
Required brace stiffness
10.19.2
m
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
mF
Effective outside punching parameter
10.11.2.3
m
Web distortional stiffness, including the effect of web
transverse stiffeners, if any, N-mm/radian.
10.19.2
m
Section property for unequal leg angles, positive for short legs
in compression and negative for long legs in compression
10.6.10.2
Δ
First-order interstory drift due to the design loads,mm.
10.3.2.2

Symbol Meaning
Section
Δ
Design story drift
10.20.15
Δ
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
Δ
Value of deformation quantity, Δ, corresponding to the
design story drift
Appendix R.6
Δ%
Value of deformation quantity, Δ, at first significant yield of
test specimen
Appendix R.6
Δ/
First-order interstory drift due to lateral forces,mm.
10.3.2.1
Δ
Deformation of weld elements at intermediate stress levels,
linearly proportioned to the critical deformation based on
distance from instantaneous center of rotation,r,mm.
10.10.2.4
Δ
Deformation of weld element at maximum stress,mm.
10.10.2.4
Δ
Deformation of weld element at ultimate stress (fracture),
usually in element furthest from instantaneous center of
rotation, mm.
10.10.2.4
δ
Deformation quantity used to control loading of test specimen  Appendix Q.6
δ%
Value of deformation quantity δ at first significant yield of test
specimen
Appendix Q.6
ρ\*
Ratio of required axial force H to required shear strength R
of a link
10.20.15
r
The chord slenderness ratio; the ratio of one-half the diameter
to the wall thickness = (2)
⁄
for round HSS; the ratio of one-
half the width to wall thickness =  (2)
⁄
for rectangular HSS
10.11.2.1,
10.11.3.1
s
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

Symbol Meaning
Section
t
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
\= 3 
⁄ , where 3 = 2 sin 8
⁄

10.11.2.1,
10.11.3.1
x
Slenderness parameter
10.6.3
λ
Limiting slenderness parameter for compact element
10.2.4
λ
Limiting slenderness parameter for compact flange
10.6.3
λ
Limiting slenderness parameter for compact web
10.6.4
λ
Limiting slenderness parameter for noncompact element
10.2.4
λ
Limiting slenderness parameter for noncompact flange
10.6.3
λ
Limiting slenderness parameter for noncompact web
10.6.4
λ,λ
Limiting slenderness parameter for compact element
10.20.8
z
Mean slip coefficient for class A or B surfaces, as Applicable,
or as established by tests
10.10.3.8
\{
Resistance factor
10.2.3.3
\{
Resistance factor
10.20.6
\{
Resistance factor for flexure
10.6.1
\{
Resistance factor for flexure
10.20.8
\{
Resistance factor for compression
10.5.1
\{
Resistance factor for compression
10.20.8
\{
Resistance factor for shear on the failure path
10.4.5.1
\{-
Resistance factor for torsion
10.8.3.1
\{
Resistance factor for tension
10.4.2
\{

Resistance factor for shear
10.7.1

Symbol Meaning
Section
\{

Resistance factor for shear strength of panel zone of beam-
to-column connections
10.20.9
\{

Resistance factor for shear
10.20.15
\{FD
Link rotation angle
Appendix Q.2
|
Safety factor
10.2.3.4
|
Safety factor
10.20.6
|
Safety factor for flexure
10.6.1
|
Safety factor for flexure = 1.67
10.20.8
|
Safety factor for compression
10.5.1
|
Safety factor for compression = 1.67
10.20.8
|
Safety factor for shear on the failure path

| 10.4.5.1                  |
| ------------------------- |
| Safety factor for torsion |
| 10.8.3.1                  |
|                           |
| Safety factor for tension |
| 10.4.2                    |
|                           |

Safety factor for shear
10.7.1
|

Safety factor for shear strength of panel zone of beam-to-
column connections
10.20.9
|F
Horizontal seismic overstrength factor
10.20.4
Angle of loading measured from the weld longitudinal axis,
degrees
10.10.2.4
Acute angle between the branch and chord, degrees
10.11.2.1
Acute angle between the branch and chord, degrees
10.11.3.1
Interstory drift angle, radians
Appendix Q.3
}
Strain hardening adjustment factor
10.20.16
ε
Strain corresponding to compressive strength of concrete, W\*
10.18.2
τ
Parameter for reduced flexural stiffness using the direct
analysis method
10.14.3

Symbol Meaning
Section
Σ∗
Moment at beam and column centerline determined by
projecting the sum of the nominal column plastic moment
strength, reduced by the axial stress H/

, 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 by ΩF, where  and the horizontal
component of  are 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
TRANSFER
The transfer of thermal energy from a point of
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
STRENGTH \*
Tensile strength of a member, equal to the specified
minimum tensile strength,  ,  multiplied by J.

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 by J%.
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-
বিন ভরষষবঃ (অওঝঈ ুশচ্ ফরসবহংরড়হ) ধ ফরংঃধহপব ড়ভ ৩৮
সস রহ:ড়:যব বিন নবুড়হফ:যব ুশচ্ ফরসবহংরড়হ.
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.