Design of Steel Members per AISC 360-16

The design of steel members according to AISC 360-16 is explained in detail under this title.

There are two main principles used in AISC 360-16.

Symbols

D = Dead load
E_m = Combined applied design force on the horizontal and vertical seismic load effects
L = Live load
L_r = roof live load
R_a = Required strength using ASD load combinations
R_u = Required strength using LRFD load combinations
R_n = Nominal strength of the applicable force transfer mechanism
S = snow load
W = Wind load
E_h = Horizontal seismic load effect
E_v = Vertical seismic load effect
Φ = Resistance factor
Ω = Safety factor

1 - Design for Strength Using Load and Resistance Factor Design (LRFD)

The required strength of members, determined by the Load and resistance factor design (LRFD) load combinations, does not exceed the design strength of the member. The design strength of the member is determined by the equation given below.

Load factors and load combinations are based on extensive statistical studies.

• 1.4D

• 1.2D + 1.6L + 0.5(L_r or S)

• 1.2D + 1.6(L_r or S) + (L or 0.5W)

• 1.2D + 1.0W + L + 0.5(Lr or S)

• 0.9D + 1.0W

• 1.2D + E_v + E_h + L + 0.2S

• 0.9D - E_v + E_h

2 - Design for Strength Using Allowable Strength Design (ASD)

The required strength of members, determined by the Allowable Strength Design (ASD) load combinations, does not exceed the allowable strength of the member. The design strength of the member is determined by the equation given below.

Load factors and load combinations are based on extensive statistical studies.

• D

• D + L

• D + (L_r or S)

• D + 0.75L + 0.75(L_r or S)

• D + 0.6W

• D + 0.75L + 0.75(0.6W) + 0.75(L_r or S)

• 0.6D + 0.6W

• 1.0D + 0.7E_v + 0.7E_h

• 1.0D + 0.525E_v + 0.525E_h + 0.75L + 0.75S

• 0.6D - 0.7E_v + 0.7E_h