Symbols · AISC 360-22

Definitions for the symbols used in this standard are provided here and reflect the defini- tions provided in the body of this standard. Some symbols may be used and defined multiple times throughout the document. The section or table number shown in the right-hand column of the list identifies the first time the symbol is used in this document. Symbols without text definitions are omitted.

Symbol	Definition	Section
A_BM	Area of the base metal, in.² (mm²)	J2.4
A_b	Nominal unthreaded body area of bolt or threaded part, in.² (mm²)	J3.7
A_b	Nominal body area of undriven rivet, in.² (mm²)	App. 5.3.2a
A_c	Area of concrete, in.² (mm²)	I1.5
A_c	Area of concrete slab within effective width, in.² (mm²)	I3.2d
A_c	Area of concrete infill, in.² (mm²)	I4.2
A_e	Effective net area, in.² (mm²)	D2
A_e	Summation of the effective areas of the cross section based on reduced effective widths, b_e, d_e, or h_e, or the area as given by Equation E7-6 or E7-7, in.² (mm²)	E7
A_e	Effective area, in.² (mm²)	E7.2
A_fc	Area of compression flange, in.² (mm²)	G2.2
A_fg	Gross area of tension flange, calculated in accordance with Section B4.3a, in.² (mm²)	F13.1
A_fn	Net area of tension flange, calculated in accordance with Section B4.3b, in.² (mm²)	F13.1
A_ft	Area of tension flange, in.² (mm²)	G2.2
A_g	Gross area of angle, in.² (mm²)	F10.2
A_g	Gross area of member, in.² (mm²)	B4.3a
A_g	Gross area of eyebar body, in.² (mm²)	D6.1
A_g	Gross area of composite member, in.² (mm²)	I2.1a
A_g	Gross cross-sectional area of member, in.² (mm²)	K1.1
A_gv	Gross area subjected to shear, in.² (mm²)	J4.2
A_n	Net area of member, in.² (mm²)	B4.3b
A_n	Area of directly connected elements, in.² (mm²)	Table D3.1
A_nt	Net area subjected to tension, in.² (mm²)	J4.3
A_nv	Net area subjected to shear, in.² (mm²)	J4.2
A_pb	Projected area in bearing, in.² (mm²)	J7
A_s	Area of steel section, in.² (mm²)	I1.5
A_s	Cross-sectional area of structural steel section, in.² (mm²)	I2.1b
A_s	Cross-sectional area of column, in.² (mm²)	App. 4.3.2a
A_sa	Cross-sectional area of steel headed stud anchor, in.² (mm²)	I8.2a
A_sf	Area on the shear failure path, in.² (mm²)	D5.1
A_sr	Area of continuous longitudinal reinforcing bars, in.² (mm²)	I2.1a
A_sr	Area of developed longitudinal reinforcing steel within the effective width of the concrete slab, in.² (mm²)	I3.2d.2

Symbol	Definition	Section
A_sw	Area of steel plates in the direction of in-plane shear, in.² (mm²)	I1.5
A_T	Nominal forces and deformations due to the design-basis fire defined in Section 4.2.1	.App. 4.1.4
A_t	Net area in tension, in.² (mm²)	App. 3.4
A_v	Shear area of the steel portion of a composite member, in.² (mm²)	I4.2
A_w	Area of web, the overall depth times the web thickness, d_tw, in.² (mm²)	. . G2.1
A_w	Area of web or webs, taken as the sum of the overall depth times the web thickness, d_tw, in.² (mm²)	G4
A_we	Effective area of the weld, in.² (mm²)	J2.4
A_wel	Effective area of longitudinally loaded fillet welds, in.² (mm²)	J2.4
A_wet	Effective area of transversely loaded fillet welds, in.² (mm²)	J2.4
A₁	Loaded area of concrete, in.² (mm²)	I6.3a
A₁	Area of steel concentrically bearing on a concrete support, in.² (mm²)	J8
A₂	Maximum area of the portion of the supporting surface that is geometrically similar to and concentric with the loaded area, in.² (mm²)	J8
B	Overall width of rectangular HSS member, measured 90° to the plane of the connection, in. (mm)	Table D3.1
B	Overall width of rectangular HSS chord member, measured 90° to the plane of the connection, in. (mm)	K1.1
B_b	Flange width of rectangular cross section, in. (mm)	App. 2.1.4
B_b	Overall width of rectangular HSS branch member or plate, measured 90° to the plane of the connection, in. (mm)	K1.1
B_e	Effective width of rectangular HSS branch member or plate for local yielding of the transverse element, in. (mm)	K1.1
B_ep	Effective width of rectangular HSS branch member or plate for punching shear, in. (mm)	K1.1
B₁	Multiplier to account for P-δ effects	App. 8.1.1
B₂	Multiplier to account for P-Δ effects	App. 8.1.1
C	HSS torsional constant, in.³ (mm³)	H3.1
C	Compressive force due to unfactored dead load and live load, kips (kN)	App. 4.3.2b
C_b	Lateral-torsional buckling modification factor for nonuniform moment diagrams when both ends of the segment are braced	F1
C_f	Constant from Table A-3.1 for the fatigue category	App. 3.3
C_m	Equivalent uniform moment factor, assuming no relative translation of member ends	App. 8.1.2
C_r	Reduction factor for shear rupture on pin-connected members	D5.1
C_v1	Web shear strength coefficient	G2.1
C_v2	Web shear buckling coefficient	G2.2
C_w	Warping constant, in.⁶ (mm⁶)	E4
C₁	Coefficient for calculation of effective rigidity of encased composite compression member	I2.1b
C₁, C₂, C₃, C₄	Material dependent constants prescribed in specified rated assembly	App. 4.3.2a
C₂	Edge distance increment, in. (mm)	Table J3.5

Symbol	Definition	Section
C₃	Coefficient for calculation of effective rigidity of filled composite compression member	I2.2b
D	Nominal dead load, kips (N)	B3.9
D	Width of stiffened element, taken as the outside diameter of round HSS, in. (mm)	B4.1b
D	Outside diameter of round HSS, in. (mm)	Table D3.1
D	Outside diameter of round HSS chord member, in. (mm)	K1.1
D	Heated perimeter of the beam, in. (mm)	. App. 4.3.2b
D	Heated perimeter of the column, in. (mm)	App. 4.3.2a
D	Inside heated perimeter of the gypsum board, in. (mm)	App. 4.3.2a
D	Outside diameter for circular columns, outside dimension for square columns, or least outside dimension for rectangular columns, in. (mm)	App. 4.3.2b
D	Nominal dead load rating	App. 5.4.2
D_b	Outside diameter of round HSS branch member, in. (mm)	K1.1
D_u	A multiplier that reflects the ratio of the mean installed bolt pretension to the specified minimum bolt pretension	J3.9
D₁	Heated perimeter of substitute beam or girder, in. (mm)	. App. 4.3.2c
E	Modulus of elasticity of steel = 29,000 ksi (200 000 MPa)	Table B4.1a
E(T)	Modulus of elasticity of steel at elevated temperature, ksi (MPa)	App. 4.2.3b
E_c	Modulus of elasticity of concrete = w_c^1.5 √f'_c, ksi (0.043w_c^1.5 √f'_c MPa).	I1.5
E_c(T)	Modulus of elasticity of concrete at elevated temperature, ksi (MPa)	App. 4.2.3b
E_s	Modulus of elasticity of steel = 29,000 ksi (200 000 MPa)	I1.5
(EI)_eff	Effective stiffness of composite section, kip-in.² (N-mm²)	I2.1b
F(T)	Engineering stress at elevated temperature, ksi (MPa)	App. 4.2.3b
F_c	Available stress in chord member, ksi (MPa)	K1.1
F_c(T)	Concrete compressive stress, ksi (MPa)	App. 4.2.3b
F_ca	Available axial stress at the point of consideration, determined in accordance with Chapter E for compression or Section D2 for tension, ksi (MPa)	H2
F_cbw, F_cbz	Available flexural stress at the point of consideration, determined in accordance with Chapter F, ksi (MPa)	H2
F_cr	Critical stress, ksi (MPa)	F2.2
F_cr	Lateral-torsional buckling stress for the section as determined by analysis, ksi (MPa)	F12.2
F_cr	Local buckling stress for the section as determined by analysis, ksi (MPa)	F12.3
F_cr	Buckling stress for the section as determined by analysis, ksi (MPa)	H3.3
F_e	Elastic buckling stress, ksi (MPa)	E3
F_el	Elastic local buckling stress determined according to Equation E7-5 or an elastic local buckling analysis, ksi (MPa)	E7.1
F_EXX	Filler metal classification strength, ksi (MPa)	Table J2.5
F_in	Nominal bond stress, ksi (MPa)	I6.3c

Symbol	Definition	Section
$F_{L}$	Nominal compression flange stress above which the inelastic buckling limit states apply, ksi (MPa)	F4.2
$F_{n}$	Nominal stress, ksi	E3
$F_{n}$	Critical buckling stress for structural steel section of filled composite members, ksi (MPa)	I2.2b
$F_{n}$	Nominal tensile stress, $F_{nt}$ , or shear stress, $F_{nv}$ , from Table J3.2, ksi (MPa)	J3.7
$F_{nBM}$	Nominal stress of the base metal, ksi (MPa)	J2.4
$F_{nt}$	Nominal tensile stress from Table J3.2, ksi (MPa)	J3.7
$F_{nt}$	Nominal tensile strength of the driven rivet from Table A-5.3.1, ksi (MPa)	App. 5.3.2a
$F_{nt}(T)$	Nominal tensile strength of the bolt, ksi (MPa)	App. 4.2.3b
$F'_{nt}$	Nominal tensile stress modified to include the effects of shear stress, ksi (MPa)	J3.8
$F_{nv}$	Nominal shear stress from Table J3.2, ksi (MPa)	J3.7
$F_{nv}$	Nominal shear strength of the driven rivet from Table A-5.3.1, ksi (MPa)	App. 5.3.2a
$F_{nv}(T)$	Nominal shear strength of the bolt, ksi (MPa)	App. 4.2.3b
$F_{nw}$	Nominal stress of the weld metal, ksi (MPa)	J2.4
$F_{p}(T)$	Proportional limit at elevated temperature	App. 4.2.3b
$F_{SR}$	Allowable stress range, ksi (MPa)	App. 3.3
$F_{TH}$	Threshold allowable stress range, maximum stress range for indefinite design life from Table A-3.1, ksi (MPa)	App. 3.3
$F_{u}$	Specified minimum tensile strength, ksi (MPa)	D2
$F_{u}$	Specified minimum tensile strength of a steel headed stud anchor, ksi (MPa)	I8.2a
$F_{u}$	Specified minimum tensile strength of the connected material, ksi (MPa)	J3.11
$F_{u}$	Specified minimum tensile strength of HSS chord member material, ksi (MPa)	K1.1
$F_{u}(T)$	Specified minimum tensile strength at elevated temperature, ksi (MPa)	App. 4.2.3b
$F_{ub}$	Specified minimum tensile strength of HSS branch member material, ksi (MPa)	K1.1
$F_{y}$	Specified minimum yield stress, ksi (MPa). As used in this Specification, "yield stress" 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)	Table B4.1a
$F_{y}$	Specified minimum yield stress of the type of steel being used, ksi (MPa)	E3
$F_{y}$	Specified minimum yield stress of the column web, ksi (MPa)	J10.6
$F_{y}$	Specified minimum yield stress of HSS chord member material, ksi (MPa)	K1.1
$F_{y}$	Specified minimum yield stress of the compression flange, ksi (MPa)	App. 8.2

Symbol	Definition	Section
$F_y(T)$	Specified minimum yield stress of steel at elevated temperature, ksi (MPa)	App. 4.2.3b
$F_{yb}$	Specified minimum yield stress of HSS branch member or plate material, ksi (MPa)	K1.1
$F_{yf}$	Specified minimum yield stress of the flange, ksi (MPa)	J10.1
$F_{ysr}$	Specified minimum yield stress of reinforcing steel, ksi (MPa)	I2.1b
$F_{yst}$	Specified minimum yield stress of the stiffener material, ksi (MPa)	G2.4
$F_{yw}$	Specified minimum yield stress of the web material, ksi (MPa)	G2.3
$F_{y,max}$	Maximum permitted yield stress of steel, ksi (MPa)	App. 2.1.4
$G$	Shear modulus of elasticity of steel = 11,200 ksi (77 200 MPa)	E4
$G(T)$	Shear modulus of elasticity of steel at elevated temperature, ksi (MPa)	App. 4.2.3b
$G_c$	Shear modulus of concrete = $0.4E_c$ , ksi (MPa)	I1.5
$G_s$	Shear modulus of steel = 11,200 ksi (77 200 MPa), ksi (MPa)	I1.5
$H$	Overall height of rectangular HSS member, measured in the plane of the connection, in. (mm) Table	D3.1
$H$	Flexural constant	E4
$H$	Maximum transverse dimension of rectangular steel member, in. (mm)	I6.3c
$H$	Overall height of rectangular HSS chord member, measured in the plane of the connection, in. (mm)	K1.1
$H$	Web depth of rectangular cross section, in. (mm)	App. 2.1.4
$H$	Ambient temperature thermal capacity of the steel column, Btu/ft- $^{\circ}$ F (kJ/m-K)	App. 4.3.2a
$H$	Total story shear, in the direction of translation being considered, produced by the lateral forces used to compute $\Delta_H$ , kips (N)	App. 8.1.3
$H_b$	Overall height of rectangular HSS branch member, measured in the plane of the connection, in. (mm)	K1.1
$I$	Moment of inertia in the plane of bending, in. $^4$ (mm $^4$ )	App. 8.1.2
$I_c$	Moment of inertia of the concrete section about the elastic neutral axis of the composite section, in. $^4$ (mm $^4$ )	I1.5
$I_s$	Moment of inertia of steel shape about the elastic neutral axis of the composite section, in. $^4$ (mm $^4$ )	I1.5
$I_{sr}$	Moment of inertia of reinforcing bars about the elastic neutral axis of the composite section, in. $^4$ (mm $^4$ )	I2.1b
$I_{st}$	Moment of inertia of transverse stiffeners about an axis in the web center for stiffener pairs, or about the face in contact with the web plate for single stiffeners, in. $^4$ (mm $^4$ )	G2.4
$I_{st1}$	Minimum moment of inertia of transverse stiffeners required for development of the full shear post buckling resistance of the stiffened web panels, $V_r = V_{c1}$ , in. $^4$ (mm $^4$ )	G2.4
$I_{st2}$	Minimum moment of inertia of transverse stiffeners required for development of web shear buckling resistance, $V_r = V_{c2}$ , in. $^4$ (mm $^4$ )	G2.4
$I_x, I_y$	Moment of inertia about the principal axes, in. $^4$ (mm $^4$ )	E4
$I_y$	Moment of inertia about the y-axis, in. $^4$ (mm $^4$ )	F2.2

Symbol	Definition	Section
$I_{yeff}$	Effective out-of-plane moment of inertia, $\text{in.}^4$ $(\text{mm}^4)$	App. 6.3.2a
$I_{yc}$	Moment of inertia of the compression flange about the $y$ -axis, $\text{in.}^4$ $(\text{mm}^4)$	F4.2
$I_{yt}$	Moment of inertia of the tension flange about the $y$ -axis, $\text{in.}^4$ $(\text{mm}^4)$	App. 6.3.2a
$J$	Torsional constant, $\text{in.}^4$ $(\text{mm}^4)$	E4
$K$	Effective length factor	E2
$K_c$	Ambient temperature thermal conductivity of the concrete, $\text{Btu/hr-ft-}^{\circ}\text{F}$ $(\text{W/m-K})$	App. 4.3.2a
$K_c$	Thermal conductivity of concrete or clay masonry unit, $\text{Btu/hr-ft-}^{\circ}\text{F}$ $(\text{W/m-K})$	App. 4.3.2a
$K_x$	Effective length factor for flexural buckling about $x$ -axis	E4
$K_y$	Effective length factor for flexural buckling about $y$ -axis	E4
$K_z$	Effective length factor for torsional buckling about the longitudinal axis	E4
$L$	Nominal live load, kips $(\text{N})$	B3.9
$L$	Laterally unbraced length of member, in. $(\text{mm})$	E2
$L$	Length of member between work points at truss chord centerlines, in. $(\text{mm})$	E5
$L$	Length of member, in. $(\text{mm})$	H3.1
$L$	Laterally unbraced length of element, in. $(\text{mm})$	J4.4
$L$	Nominal occupancy live load, kips $(\text{N})$	App. 4.1.4
$L$	Interior dimension of one side of a square concrete box protection, in. $(\text{mm})$	App. 4.3.2a
$L$	Nominal live load rating	App. 5.4.2
$L$	Length of span, in. $(\text{mm})$	App. 6.3.2a
$L$	Height of story, in. $(\text{mm})$	App. 7.3.2
$L_b$	Length between points that are either braced against lateral displacement of compression flange or braced against twist of the cross section, in. $(\text{mm})$	F2.2
$L_b$	Laterally unbraced length of member, in. $(\text{mm})$	F10.2
$L_b$	Length between points that are either braced against lateral displacement of the compression region, or between points braced to prevent twist of the cross section, in. $(\text{mm})$	F11.2
$L_b$	Largest laterally unbraced length along either flange at the point of load, in. $(\text{mm})$	J10.4
$L_{br}$	Unbraced length within the panel under consideration, in. $(\text{mm})$	App. 6.2.1
$L_{br}$	Unbraced length adjacent to the point brace, in. $(\text{mm})$	App. 6.2.2
$L_c$	Effective length of member, in. $(\text{mm})$	E2
$L_c$	Effective length of member for buckling about the minor axis, in. $(\text{mm})$	E5
$L_c$	Effective length of built-up member, in. $(\text{mm})$	E6.1
$L_c$	Column effective length, ft $(\text{mm})$	App. 4.3.2b
$L_{cx}$	Effective length of member for buckling about $x$ -axis, in. $(\text{mm})$	E4
$L_{cy}$	Effective length of member for buckling about $y$ -axis, in. $(\text{mm})$	E4
$L_{cz}$	Effective length of member for buckling about longitudinal axis, in. $(\text{mm})$	E4

Symbol	Definition	Section
L_cl	Effective length in the plane of bending, calculated based on the assumption of no lateral translation at the member ends, set equal to the laterally unbraced length of the member unless analysis justifies a smaller value, in. (mm)	. . App. 8.1.2
L_in	Load introduction length, determined in accordance with Section I6.4, in. (mm)	I6.3c
L_p	Limiting laterally unbraced length for the limit state of yielding, in. (mm)	F2.2
L_r	Limiting laterally unbraced length for the limit state of inelastic lateral-torsional buckling, in. (mm)	F2.2
L_r	Nominal roof live load	App. 5.4.2
L_v	Distance from maximum to zero shear force, in. (mm)	G5
L_x, L_y, L_z	Laterally unbraced length of the member for each axis, in. (mm)	E4
M_A	Absolute value of moment at quarter point of the unbraced segment, kip-in. (N-mm)	F1
M_B	Absolute value of moment at centerline of the unbraced segment, kip-in. (N-mm)	F1
M_br	Required flexural strength of the brace, kip-in. (N-mm) . . App. 6.3.2a
M_c	Absolute value of moment at three-quarter point of the unbraced segment, kip-in. (N-mm)	F1
M_c	Available flexural strength, φ_bM_n or M_n/Ω_b, determined in accordance with Chapter F, kip-in. (N-mm)	H1.1
M_c	Design flexural strength, determined in accordance with Section I3, kip-in. (N-mm)	I5
M_c	Allowable flexural strength, determined in accordance with Section 13, kip-in. (N-mm)	I5
M_c-ip	Available strength for in-plane bending, kip-in. (N-mm)	Table K4.1
M_c-op	Available strength for out-of-plane bending, kip-in. (N-mm)	Table K4.1
M_cr	Elastic lateral-torsional buckling moment, kip-in. (N-mm)	F10.2
M_cx	Available lateral-torsional strength for major-axis flexure determined in accordance with Chapter F using C_b = 1.0, kip-in. (N-mm)	H1.3
M_cx	Available flexural strength about x-axis for the limit state of tensile rupture of the flange, φ_bM_n or M_n/Ω_b, determined according to Section F13.1, kip-in. (N-mm)	H4
M_cx, M_cy	Available flexural strength, φ_bM_n or M_n/Ω_b, determined in accordance with Chapter F, kip-in. (N-mm)	H3.2
M_lt	First-order moment using LRFD or ASD load combinations, due to lateral translation of the structure only, kip-in. (N-mm)	App. 8.1.1
M_max	Absolute value of maximum moment in the unbraced segment, kip-in. (N-mm)	F1
M_mid	Moment at middle of unbraced length, kip-in. (N-mm)	App. 1.3.2c
M_n	Nominal flexural strength, kip-in. (N-mm)	F1
M_n	Nominal flexural strength at ambient temperature calculated in accordance with provisions of Chapter I, kip-in. (N-mm) App. 4.2.4d

Symbol	Definition	Section
$M_{n}$	Nominal flexural strength due to yielding at ambient temperature determined in accordance with the provisions in Section F2.1, kip-in. (N-mm)	App. 4.2.4e
$M_{nt}$	First-order moment using LRFD or ASD load combinations, with the structure restrained against lateral translation, kip-in. (N-mm)	App. 8.1.1
$M_{p}$	Plastic moment, kip-in. (N-mm)	Table B4.1b
$M_{p}$	Moment corresponding to plastic stress distribution over the composite cross section, kip-in. (N-mm)	I3.4b
$M_{pf}$	Plastic moment of a section composed of the flange and a segment of the web with a depth, $d_{e}$ , kip-in. (N-mm)	G2.3
$M_{pm}$	Smaller of $M_{pf}$ and $M_{pst}$ , kip-in. (N-mm)	G2.3
$M_{pst}$	Plastic moment of a section composed of the end stiffener plus a length of web equal to $d_{e}$ plus the distance from the inside face of the stiffener to the end of the beam, except that the distance from the inside face of the stiffener to the end of the beam shall not exceed $0.84t_{w}\sqrt{E/F_{y}}$ for calculation purposes, kip-in. (N-mm)	G2.3
$M_{r}$	Required flexural strength, determined in accordance with Chapter C, using LRFD or ASD load combinations, kip-in. (N-mm)	H1.1
$M_{r}$	Required flexural strength, determined in accordance with Section I1.5, using LRFD or ASD load combinations, kip-in. (N-mm)	I5
$M_{r}$	Required flexural strength using LRFD or ASD load combinations, kip-in. (N-mm)	J10.4
$M_{r}$	Required flexural strength of the beam within the panel under consideration, using LRFD or ASD load combinations, kip-in. (N-mm)	App. 6.3.1a
$M_{r}$	Largest of the required flexural strengths of the beam within the unbraced lengths adjacent to the point brace, using LRFD or ASD load combinations, kip-in. (N-mm)	App. 6.3.1b
$M_{r}$	Required second-order flexural strength using LRFD or ASD load combinations, kip-in. (N-mm)	App. 8.1.1
$M_{ro}$	Required flexural strength in the HSS chord member at a joint, on the side of joint with lower compression stress for round HSS and higher compression stress for rectangular HSS, kip-in. (N-mm)	K1.3
$M_{r\text{-}ip}$	Required in-plane flexural strength in branch using LRFD or ASD load combinations, kip-in. (N-mm)	Table K4.1
$M_{r\text{-}op}$	Required out-of-plane flexural strength in branch using LRFD or ASD load combinations, kip-in. (N-mm)	Table K4.1
$M_{rx}$	Required flexural strength at the location of the bolt holes, determined in accordance with Chapter C, using LRFD or ASD load combinations, positive for tension and negative for compression in the flange under consideration, kip-in. (N-mm)	H4
$M_{rx}$ , $M_{ry}$	Required flexural strength, determined in accordance with Chapter C, using LRFD or ASD load combinations, kip-in. (N-mm)	H3.2
$M_{u}$	Required flexural strength at elevated temperature, determined using the load combination in Equation A-4-1 and greater than 0.01 $M_{n}$ , kip-in. (N-mm)	App. 4.2.4e

Symbol	Definition	Section
M_y	Moment at yielding of the extreme fiber, kip-in. (N-mm)	Table B4.1b
M_y	Yield moment about the axis of bending, kip-in. (N-mm)	F9.1
M_y	Yield moment calculated using the geometric section modulus, kip-in. (N-mm)	F10.2
M_yc	Yield moment corresponding to yielding of the tension flange and first yield of the compression flange, kip-in. (N-mm)	I3.4b
M_yc	Yield moment in the compression flange, kip-in. (N-mm)	F4.1
M_yt	Yield moment in the tension flange, kip-in. (N-mm)	F4.4
M'₁	Effective moment at the end of the unbraced length opposite from M₂, kip-in. (N-mm)	App. 1.3.2c
M₁	Smaller moment at end of unbraced length, kip-in. (N-mm)	App. 1.3.2c
M₂	Larger moment at end of unbraced length, kip-in. (N-mm)	App. 1.3.2c
N_i	Notional load applied at level i, kips (N)	C2.2b
N_i	Additional lateral load applied at any level, kips (N)	App. 7.3.2
P_br	Required strength of end and intermediate point braces, kips (N)	App. 6.2.2
P_c	Available compressive strength, φP_n or P_n/Ω_c, determined in accordance with Chapter E, kips (N)	H1.1
P_c	Available tensile strength, φP_n or P_n/Ω_t, determined in accordance with Chapter D, kips (N)	H1.2
P_c	Available compressive strength in plane of bending, kips (N)	H1.3
P_c	Available tensile or compressive strength, φP_n or P_n/Ω, determined in accordance with Chapter D or E, kips (N)	H3.2
P_c	Available axial strength for the limit state of tensile rupture of the net section at the location of bolt holes, φP_n or P_n/Ω_t, determined in accordance with Section D2(b), kips (N)	H4
P_c	Allowable axial strength, determined in accordance with Section I2, kips (N)	I5
P_c	Design axial strength, determined in accordance with Section I2, kips (N)	I5
P_c	Available axial strength obtained from Table K3.1, kips (N)	Table K4.1
P_cy	Available compressive strength out of the plane of bending, kips (N)	H1.3
P_e	Elastic critical buckling load determined in accordance with Chapter C or Appendix 7, kips (N)	I2.1b
P_{e story}	Elastic critical buckling strength for the story in the direction of translation being considered, kips (N)	App 8.1.3
P_el	Elastic critical buckling strength of the member in the plane of bending, kips (N)	App. 8.1.2
P_lt	First-order axial force using LRFD or ASD load combinations, due to lateral translation of the structure only, kips (N)	App. 8.1.1
P_mf	Total vertical load in columns in the story that are part of moment frames, if any, in the direction of translation being considered, kips (N)	App. 8.1.3
P_n	Nominal compressive strength, kips (N)	E1
P_n	Nominal axial strength, kips (N)	App. 2.1.4
P_n	Nominal compressive strength at ambient temperature determined in accordance with Section E3, kips (N)	App. 4.2.4e

Symbol	Definition	Section
Pno	Nominal axial compressive strength without consideration of length effects, kips (N)	I2.1b
Pns	Cross-section compressive strength, kips (N)	C2.3
Pnt	First-order axial force using LRFD or ASD load combinations, with the structure restrained against lateral translation, kips (N)	App. 8.1.1
Pp	Nominal bearing strength, kips (N)	J8
Pp	Plastic axial compressive strength, kips (N)	I2.2b
Pr	Required axial compressive strength using LRFD or ASD load combinations, kips (N)	C2.3
Pr	Required compressive strength determined in accordance with Chapter C using LRFD or ASD load combinations, kips (N)	H1.1
Pr	Required tensile strength determined in accordance with Chapter C using LRFD or ASD load combinations, kips (N)	H1.2
Pr	Required axial strength determined in accordance with Chapter C using LRFD or ASD load combinations, kips (N)	H3.2
Pr	Required axial strength of the member at the location of the bolt holes determined in accordance with Chapter C using LRFD or ASD load combinations, positive in tension and negative in compression, kips (N)	H4
Pr	Required axial strength, determined in accordance with Section 11.5 using LRFD or ASD load combinations, kips (N)	I5
Pr	Required external force applied to the composite member, kips (N)	I6.2a
Pr	Required axial strength using LRFD or ASD load combinations, kips (N)	J10.6
Pr	Required axial strength in branch using LRFD or ASD load combinations, kips (N)	Table K4.1
Pr	Required axial strength of the column within the panel under consideration using LRFD or ASD load combinations, kips (N)	App. 6.2.1
Pr	Largest of the required axial strengths of the column within the unbraced lengths adjacent to the point brace using LRFD or ASD load combinations, kips (N)	App. 6.2.2
Pr	Required second-order axial strength using LRFD or ASD load combinations, kips (N)	App. 8.1.1
Pro	Required axial strength in the HSS chord member at a joint, on the side of joint with lower compression stress for round HSS and higher compression stress for rectangular HSS, kips (N)	K1.3
Pstory	Total vertical load supported by the story using LRFD or ASD load combinations, as applicable, including loads in columns that are not part of the lateral force-resisting system, kips (N)	App. 8.1.3
Pu	Required axial strength in compression using LRFD load combinations, kips (N)	App. 1.3.2b
Pu	Required compressive strength at elevated temperature, determined using the load combination in Equation A-4-1, kips (N)	App. 4.2.4e
Py	Axial yield strength of the column, kips (N)	J10.6
Qct	Available tensile strength, determined in accordance with Section 18.3b, kips (N)	I8.3c

Symbol	Definition	Section
Qcv	Available shear strength, determined in accordance with Section 18.3a, kips (N)	18.3c
Qf	Chord-stress interaction parameter	J10.3
Qn	Nominal shear strength of one steel headed stud or steel channel anchor, kips (N)	13.2d
Qne	Nominal tested strength of shear connections, kips (N)	18.4b
Qnt	Nominal tensile strength of steel headed stud anchor, kips (N)	18.3b
Qnv	Nominal shear strength of steel headed stud anchor, kips (N)	18.3a
Qrt	Required tensile strength, kips (N)	18.3c
Qrv	Required shear strength, kips (N)	18.3c
R	Radius of joint surface, in. (mm)	Table J2.2
R	Transition radius, in. (mm)	Table A-3.1
R	Fire endurance at equilibrium moisture conditions, min	App. 4.3.2a
R	Fire resistance, min	App. 4.3.2a
R	Fire-resistance rating of column assembly, hr	App. 4.3.2a
R	Fire-resistance rating, hr	App. 4.3.2b
R	Nominal load due to rainwater or snow, exclusive of ponding contribution	App. 5.4.2
Ra	Required strength using ASD load combinations	B3.2
R_FIL	Reduction factor for joints using a pair of transverse fillet welds only	App. 3.3
R_n	Nominal strength	B3.1
R_n	Nominal bond strength, kips (N)	I6.3c
R_n	Nominal slip resistance, kips (N)	J1.8
R_n	Nominal strength of the connected material, kips (N)	J3.11
R_n	Nominal yielding strength at ambient temperature determined in accordance with Section D2, kips (N)	App. 4.2.4e
R_o	Fire endurance at zero moisture content, min	App. 4.3.2a
R_pc	Web plastification factor, determined in accordance with Section F4.2(c)(6)	F4.1
R_pg	Bending strength reduction factor	F5.2
R_PJP	Reduction factor for reinforced or nonreinforced transverse partial-joint-penetration (PJP) groove welds	App. 3.3
R_pt	Web plastification factor corresponding to the tension flange yielding limit state	F4.4
R_u	Required tensile strength at elevated temperature, determined using the load combination in Equation A-4-1 and greater than 0.01R_n, kips (N)	App. 4.2.4e
R_u	Required strength using LRFD load combinations	B3.1
S	Elastic section modulus about the axis of bending, in.³ (mm³)	F7.2
S	Nominal snow load, kips (N)	App. 4.1.4
S_c	Elastic section modulus, in.³ (mm³)	F9.4
S_c	Elastic section modulus to the toe in compression relative to the axis of bending, in.³ (mm³)	F10.3
S_e	Effective section modulus determined with the effective width of the compression flange, in.³ (mm³)	F7.2

Symbol	Definition	Section
S_ip	Effective elastic section modulus of welds for in-plane bending, in.³ (mm³)	K5
S_min	Minimum elastic section modulus relative to the axis of bending, in.³ (mm³)	F12
S_op	Effective elastic section modulus of welds for out-of-plane bending, in.³ (mm³)	K5
S_x	Elastic section modulus taken about the x-axis, in.³ (mm³)	F2.2
S_x	Minimum elastic section modulus taken about the x-axis, in.³ (mm³)	F13.1
S_xc, S_xt	Elastic section modulus referred to compression and tension flanges, respectively, in.³ (mm³)	Table B4.1b
S_y	Elastic section modulus taken about the y-axis, in.³ (mm³)	F6.1
T	Elevated temperature of steel due to unintended fire exposure, °F (°C)	App. 4.2.4d
T	Temperature of steel, °F (°C)	App. 4.2.4d
T_a	Required tension force using ASD load combinations, kips (kN)	J3.10
T_b	Minimum fastener pretension given in Table J3.1 or Table J3.1M, kips (kN)	J3.9
T_c	Available torsional strength, φ_TT_n or T_n/Ω_T, determined in accordance with Section H3.1, kip-in. (N-mm)	H3.2
T_cr	Critical temperature in °F (°C)	App. 4.2.4e
T_e	Equivalent thickness of concrete or clay masonry unit, in accordance with ACI 216.1 (ACI 216.1M), in. (mm)	App. 4.3.2a
T_r	Required torsional strength, determined in accordance with Chapter C, using LRFD or ASD load combinations, kip-in. (N-mm)	H3.2
T_u	Required tension force using LRFD load combinations, kips (kN)	J3.10
T₁	Thickness of fire protection materials calculated for the substitute beam or girder, in. (mm)	App. 4.3.2c
U	Shear lag factor	D3
V'	Nominal shear force between the steel beam and the concrete slab transferred by steel anchors, kips (N)	I3.2d
V_br	Required shear strength of the bracing system, kips (N)	App. 6.2.1
V_e	Available shear strength, φ_vV_n or V_n/Ω_v, determined in accordance with Chapter G, kips (N)	H3.2
V_c1	Available shear strength calculated with V_n as defined in Section G2.1 or G2.2. as applicable, kips (N)	G2.4
V_c2	Available shear strength, kips (N)	G2.4
V_n	Nominal shear strength, kips (N)	G1
V_r	Required shear strength in the panel being considered, kips (N)	G2.4
V_r	Required shear strength, determined in accordance with Chapter C, using LRFD or ASD load combinations, kips (N)	H3.2
V'_r	Required shear force to be transferred to the steel or concrete, kips (N)	I6.1
W	Nominal weight of steel shape, lb/ft (kg/m)	App. 4.3.2a
W	Weight of columns, lb/ft (kg/m)	App. 4.3.2a
W	Average weight of column, lb/ft (kg/m)	App. 4.3.2a
W	Weight of beam or girder, lb/ft (kg/m)	App. 4.3.2c

Symbol	Definition	Section
W'	Total weight of steel shape and gypsum wallboard protection, lb/ft (kg/m)	App. 4.3.2a
W₁	Weight of substitute beam or girder, lb/ft (kg/m)	App. 4.3.2c
Y_i	Gravity load applied at level i from the LRFD load combination or ASD load combination, as applicable, kips (N)	C2.2b
Z	Plastic section modulus taken about the axis of bending, in.³ (mm³)	F7.1
Z_b	Plastic section modulus of branch taken about the axis of bending, in.³ (mm³)	K4.1
Z_x	Plastic section modulus taken about the x-axis, in.³ (mm³)	Table B4.1b
Z_y	Plastic section modulus taken about the y-axis, in.³ (mm³)	F6.1
a	Shortest distance from edge of pin hole to edge of member measured parallel to the direction of force, in. (mm)	D5.1
a	Distance between connectors, in. (mm)	E6.1
a	Clear distance between transverse stiffeners, in. (mm)	F13.2
a	Detail length, in. (mm)	Table A-3.1
a_w	Ratio of 2 times the web area in compression to the compression flange area	F13.2
b	Width of compression element as shown in Table B4.1, in. (mm)	B4.1
b	Width of the element, in. (mm)	E7.1
b	Width of compression flange as defined in Section B4.1b, in. (mm)	F7.2
b	Width of leg, in. (mm)	F10.2
b	Full width of leg in compression, in. (mm)	F10.3
b	Width of the leg resisting the shear force or depth of tee stem, in. (mm)	G3
b	Largest clear distance between rows of steel anchors or ties, in. (mm)	I1.6a
b	Thickness of attachment, in. (mm)	Table A-3.1
b_cf	Width of column flange, in. (mm)	J10.6
b_e	Effective width, in. (mm)	E7.1
b_f	Width of flange, in. (mm)	B4.1
b_f	Width of column flange, in. (mm)	App. 4.3.2a
b_fc	Width of compression flange, in. (mm)	F4.2
b_ft	Width of tension flange, in. (mm)	G2.2
b_l	Length of longer leg of angle, in. (mm)	E5
b_p	Smaller of the dimensions a and h, in. (mm)	G2.4
b_s	Length of shorter leg of angle, in. (mm)	E5
b_s	Stiffener width for one-sided stiffeners; twice the individual stiffener width for pairs of stiffeners, in. (mm)	App. 6.3.2a
c	Distance from the neutral axis to the extreme compressive fibers, in. (mm)	App. 6.3.2a
c_c	Ambient temperature specific heat of concrete, Btu/lb-°F (kJ/kg-K)	App. 4.3.2a
c₁	Effective width imperfection adjustment factor determined from Table E7.1	E7.1
d	Full depth of the section, for stems of tees, in. (mm)	B4.1a
d	Depth of section, in. (mm)	Table D3.1

Symbol	Definition	Section
d	Depth of section from which the tee was cut, in. (mm)	Table D3.1
d	Diameter of pin, in. (mm)	D5.1
d	Depth of tee or width of web leg in tension, in. (mm)	F9.2
d	Depth of tee or width of web leg in compression, in. (mm)	F9.2
d	Nominal diameter of fastener, in. (mm)	J3.4
d	Diameter, in. (mm)	J7
d	Full nominal depth of member, in. (mm)	J10.2
d	Depth of column, in. (mm)	App. 4.3.2a
d_b	Depth of beam, in. (mm)	J10.6
d_b	Nominal diameter (body or shank diameter), in. (mm)	App. 3.4
d_c	Depth of column, in. (mm)	J10.6
d_e	Effective width for tees, in. (mm)	E7.1
d_h	Diameter of hole, in. (mm)	D5.1
d_m	Density of the concrete or clay masonry unit, lb/ft³ (kg/m³)	App. 4.3.2a
d_sa	Diameter of steel headed stud anchor, in. (mm)	I8.1
d_tie	Effective diameter of the tie bar, in. (mm)	I1.6b
e	Eccentricity in a truss connection, positive being away from the branches, in. (mm)	K3.1
e_mid-ht	Distance from the edge of steel headed stud anchor shank to the steel deck web, in. (mm)	I8.2a
f'_c	Specified compressive strength of concrete, ksi (MPa)	I1.2a
f'_c	28-day compressive strength of concrete, ksi (MPa)	App. 4.3.2b
f'_c(T)	Specified compressive strength of concrete at elevated temperature, ksi (MPa)	App. 4.2.3b
f_ra	Required axial stress at the point of consideration, determined in accordance with Chapter C, using LRFD or ASD load combinations, ksi (MPa)	H2
f_rbw, f_rbz	Required flexural stress at the point of consideration, determined in accordance with Chapter C, using LRFD or ASD load combinations, ksi (MPa)	H2
f_rv	Required shear stress using LRFD or ASD load combinations, ksi (MPa)	J3.8
g	Transverse center-to-center spacing (gage) between fastener gage lines, in. (mm)	B4.3b
g	Gap between toes of branch members in a gapped K-connection, neglecting the welds, in. (mm)	K3.1
h	Width of compression element as shown in Table B4.1, in. (mm)	B4.1
h	Depth of web, as defined in Section B4.1b, in. (mm)	F7.3
h	Clear distance between flanges less the fillet at each flange, in. (mm)	G2.1
h	For built-up welded sections, the clear distance between flanges, in. (mm)	G2.1
h	For built-up bolted sections, the distance between fastener lines, in. (mm)	G2.1

Symbol	Definition	Section
$h$	Width resisting the shear force, taken as the clear distance between the flanges less the inside corner radius on each side for HSS or the clear distance between flanges for box sections; for built-up welded sections, the clear distance between flanges; for built-up bolted sections, the distance between fastener lines, in. (mm)	G4
$h$	Flat width of longer side, as defined in Section B4.1b(d), in. (mm)	H3.1
$h$	Total nominal thickness of Type X gypsum wallboard, in. (mm)	App. 4.3.2a
$h$	Thickness of the concrete cover, measured between the exposed concrete and nearest outer surface of the encased steel column section, in. (mm)	App. 4.3.2a
$h$	Thickness of sprayed fire-resistant material, in. (mm)	App. 4.3.2a
$h_{c}$	Twice the distance from the center of gravity 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, in. (mm)	B4.1b
$h_{e}$	Effective width for webs, in. (mm)	E7.1
$h_{f}$	Factor for fillers	J3.9
$h_{o}$	Distance between flange centroids, in. (mm)	E4
$h_{p}$	Twice the distance from the plastic neutral axis to the nearest line of fasteners at the compression flange or the inside face of the compression flange when welds are used, in. (mm)	B4.1b
$h_{1}$	Concrete slab thickness above steel deck, in. (mm)	App. 4.3.2f
$h_{2}$	Depth of steel deck, in. (mm)	App. 4.3.2f
$k$	Distance from outer face of flange to the web toe of fillet, in. (mm)	J10.2
$k_{E}$ , $k_{p}$ , $k_{y}$	Retention factors for steel	App. 4.2.3b
$k_{Ec}$ , $k_{c}$	Retention factors for concrete	App. 4.2.3b
$k_{b}$	Retention factor for high-strength bolts	App. 4.2.3b
$k_{c}$	Coefficient for slender unstiffened elements: Table	B4.1
$k_{ds}$	Directional strength increase factor	J2.4
$k_{sb}$	Retention factor depending on bottom flange temperature, $T$ , as given in Table A-4.2.4	App. 4.2.4d
$k_{v}$	Web plate shear buckling coefficient	G2.1
$l$	Actual length of end-loaded weld, in. (mm)	J2.2
$l$	Length of connection, in. (mm): Table	D3.1
$l_{a}$	Length of channel anchor, in. (mm)	I8.2b
$l_{b}$	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 loaded cap plates), in. (mm)	K2.1
$l_{b}$	Length of bearing, in. (mm)	J7
$l_{c}$	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, in. (mm)	J3.11
$l_{e}$	Total effective weld length of groove and fillet welds to HSS for weld strength calculations, in. (mm)	K5

Symbol	Definition	Section
l_end	Distance from the near side of the connecting branch or plate to end of chord, in. (mm)	K1.1
l_ov	Overlap length measured along the connecting face of the chord beneath the two branches, in. (mm)	K3.1
l_p	Projected length of the overlapping branch on the chord, in. (mm)	K3.1
l₁	Largest upper width of deck rib, in. (mm)	App. 4.3.2f
l₂	Bottom width of deck rib, in (mm)	App. 4.3.2f
l₃	Width of deck upper flange, in (mm)	App. 4.3.2f
m	Equilibrium moisture content of concrete by volume, %	App. 4.3.2a
m	Moisture content of the concrete slab, %	App. 4.3.2f
n	Number of braced points within the span	App. 6.3.2a
n	Threads per inch (per mm)	App. 3.4
n_b	Number of bolts carrying the applied tension	J3.10
n_s	Number of slip planes required to permit the connection to slip	J3.9
n_SR	Number of stress range fluctuations in design life	App. 3.3
p	Inner perimeter of concrete or clay masonry protection, in. (mm)	App. 4.3.2a
p	Pitch, in. per thread (mm per thread)	App. 3.4
P_b	Perimeter of the steel-concrete bond interface within the composite cross section, in. (mm)	I6.3c
P_c	Concrete density, lb/ft³ (kg/m³)	App. 4.3.2a
r	Radius of gyration, in. (mm)	E2
r_a	Radius of gyration about the geometric axis parallel to the connected leg, in. (mm)	E5
r_i	Minimum radius of gyration of individual component, in. (mm)	E6.1
r̅_o	Polar radius of gyration about the shear center, in. (mm)	E4
r_t	Effective radius of gyration for lateral-torsional buckling. For I-shapes with a channel cap or a cover plate attached to the compression flange, 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, in. (mm)	F4.2
r_x	Radius of gyration about x-axis, in. (mm)	E4
r_y	Radius of gyration about y-axis, in. (mm)	E4
r_y	Radius of gyration about minor axis, in. (mm)	App. 1.3.2c
r_z	Radius of gyration about the minor principal axis, in. (mm)	E5
s	Longitudinal center-to-center spacing (pitch) of any two consecutive bolt holes, in. (mm)	B4.3b
S_t	Largest clear spacing of the ties, in. (mm)	I1.6b
t	Design wall thickness of HSS member, in. (mm)	B4.2
t	Thickness of plate, in. (mm)	D5.1
t	Thickness of wall, in. (mm)	E7.2
t	Thickness of angle leg, in. (mm)	F10.2
t	Thickness of angle leg or tee stem, in. (mm)	G3
t	Thickness of web, in. (mm)	G4
t	Thickness of connected material, in. (mm)	J3.11
t	Total thickness of fillers, in. (mm)	J5.2

Symbol	Definition	Section
t	Design wall thickness of HSS chord member, in. (mm)	K1.1
t	Distance from the neutral axis to the extreme tensile fibers, in. (mm)	App. 6.3.2a
tb	Design wall thickness of HSS branch member or thickness of plate, in. (mm)	K1.1
tcf	Thickness of column flange, in. (mm)	J10.6
tf	Thickness of flange, in. (mm)	F3.2
tf	Thickness of the loaded flange, in. (mm)	J10.1
tf	Thickness of channel anchor flange, in. (mm)	I8.2b
tfc	Thickness of compression flange, in. (mm)	F4.2
tp	Thickness of tension loaded plate, in. (mm)	App. 3.3
tsc	Thickness of composite plate shear wall, in. (mm)	I1.6b
tst	Thickness of web stiffener, in. (mm)	App. 6.3.2a
tw	Thickness of web, in. (mm)	F4.2
tw	Thickness of channel anchor web, in. (mm)	I8.2b
tw	Thickness of column web, in. (mm)	J10.6
tw	Smallest effective weld throat thickness around the perimeter of branch or plate, in. (mm)	K5
tw	Thickness of beam web, in. (mm)	App. 6.3.2a
W	Width of plate, in. (mm)	Table D3.1
W	Width of cover plate, in. (mm)	F13.3
W	Size of weld leg, in. (mm)	J2.2b
W	Subscript relating symbol to major principal axis bending	H2
W	Leg size of the reinforcing or contouring fillet, if any, in the direction of the thickness of the tension-loaded plate, in. (mm)	App. 3.3
wc	Weight of concrete per unit volume (90 ≤ wc≤ 155 lb/ft³ or 1500 ≤ wc≤ 2500 kg/m³)	I1.5
wr	Average width of concrete rib or haunch, in. (mm)	I3.2c
x	Subscript relating symbol to major-axis bending	H1.1
xa	Bracing offset distance along x-axis, in. (mm)	E4
xo, yo	Coordinates of the shear center with respect to the centroid, in. (mm)	E4
x̄	Eccentricity of connection, in. (mm)	Table D3.1
y	Subscript relating symbol to minor-axis bending	H1.1
ya	Bracing offset distance along y-axis, in. (mm)	E4
z	Subscript relating symbol to minor principal axis bending	H2
Δ	First-order interstory drift due to the LRFD or ASD load combinations, in. (mm)	App. 7.3.2
ΔH	First-order interstory drift, in the direction of translation being considered, due to lateral forces, in. (mm)	App. 8.1.3
Ω	Safety factor	B3.2
Ωb	Safety factor for flexure	I5
Ωc	Safety factor for compression	I5
β	Reduction factor	J2.2b
β	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	K1.1

Symbol	Definition	Section
$\beta _{T}$	Overall brace system required stiffness, kip-in./rad (N-mm/rad)	App. 6.3.2a
$\beta _{br}$	Required shear stiffness of the bracing system, kip/in. (N/mm)	App. 6.2.1
$\beta _{br}$	Required flexural stiffness of the brace, kip/in. (N/mm)	App. 6.3.2a
$\beta _{eff}$	Effective width ratio; the sum of the perimeters of the two branch members in a K-connection divided by eight times the chord width	K1.1
$\beta _{sec}$	Web distortional stiffness, including the effect of web transverse stiffeners, if any, kip-in./rad (N-mm/rad)	App. 6.3.2a
$\beta _{w}$	Section property for single angles about major principal axis, in. (mm)	F10.2
$\gamma$	Chord slenderness ratio; the ratio of one-half the diameter to the wall thickness for round HSS; the ratio of one-half the width to wall thickness for rectangular HSS	K1.1
$\varepsilon (T)$	Engineering strain at elevated temperature, in./in.(mm/mm)	App. 4.2.3b
$\varepsilon _{c}(T)$	Concrete compressive strain, in./in. (mm/mm)	App. 4.2.3b
$\varepsilon _{cu}(T)$	Concrete strain corresponding to $f_{c}^{\prime }(T)$ at elevated temperature, in./in. (mm/mm)	App. 4.2.3b
$\varepsilon _{p}(T)$	Engineering strain at the proportional limit at elevated temperature, in./in. (mm/mm)	App. 4.2.3b
$\varepsilon _{u}(T)$	Ultimate strain at elevated temperature, in./in. (mm/mm)	App. 4.2.3b
$\varepsilon _{y}(T)$	Engineering yield strain at elevated temperature, in./in. (mm/mm)	App. 4.2.3b
$\zeta$	Gap ratio; the ratio of the gap between the branches of a gapped K-connection to the width of the chord for rectangular HSS	K3.1
$\eta$	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	K1.1
$\theta$	Angle between the line of action of the required force and the weld longitudinal axis, degrees	J2.4
$\theta$	Acute angle between the branch and chord, degrees	K1.1
$\lambda$	Width-to-thickness ratio for the element as defined in Section B4.1	E7.1
$\lambda _{p}$	Limiting width-to-thickness ratio (compact/noncompact)	Table B4.1b
$\lambda _{pf}$	Limiting width-to-thickness ratio for compact flange, as defined in Table B4.1b	F3.2
$\lambda _{pw}$	Limiting width-to-thickness ratio for compact web, as defined in Table B4.1b	F4.2
$\lambda _{r}$	Limiting width-to-thickness ratio (noncompact/slender)	Table B4.1b
$\lambda _{r}$	Limiting width-to-thickness ratio (nonslender/slender)	Table B4.1a
$\lambda _{rf}$	Limiting width-to-thickness ratio for noncompact flange, as defined in Table B4.1b	F3.2
$\lambda _{rw}$	Limiting width-to-thickness ratio for noncompact web, as defined in Table B4.1b	F4.2
$\mu$	Mean slip coefficient for Class A or B surfaces, as applicable, or as established by tests	J3.9
$\rho _{sr}$	Reinforcement ratio for continuous longitudinal reinforcement	I2.1
$\rho _{w}$	Maximum shear ratio within the web panels on each side of the transverse stiffener	G2.4

Symbol	Definition	Section
τ_b	Stiffness reduction parameter	C2.3
Φ	Resistance factor	B3.1
Φ_b	Resistance factor for flexure	I5
Φ_c	Resistance factor for compression	I5