Load Combination and Strength Design per ASCE 7-16 §2.3

Symbols

E_m = Combined applied design force on the horizontal and vertical seismic load effects
E_mh= The effect of horizontal seismic forces including overstrength
E_v = Vertical seismic load effect

LOAD COMBINATIONS FOR STRENGTH DESIGN (Reinforced Concrete, LRFD)

Basic Combinations

Basic load combinations used for the strength design are given below.

• 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

Basic Combinations with Seismic Load Effects

E = f (E_v; E_h) (defined in Section 12.4.2 or 12.4.3.1) is combined with the effects of other loads, according to ASCE 7-16 Section 2.3.1, basic combinations below is considered.

• 1.2D + E_v + E_h + L + 0.2S

• 0.9D - E_v + E_h

Where the seismic load effect with overstrength, E_m = f(E_v; E_mh), defined in Section 12.4.3, is combined with the effects of other loads, the following seismic load combination for structures is applied:

• 1.2D + E_v + E_mh + L + 0.2S

• 0.9D - E_v + E_mh

The principal loads in the load combinations are identified in Table C2.3-1.

Load combination requirements in Section 2.3 apply only to strength limit states. Serviceability limit states and associated load factors are covered in Appendix C of ASCE 7-16.

• 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

LOAD COMBINATIONS FOR ALLOWABLE STRESS DESIGN - (ASD)

Basic Combinations

Basic load combinations used for the strength design are given below.

• 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

Basic Combinations with Seismic Load Effects

When a structure is subject to seismic load effects, the following load combinations is applied in addition to the basic combinations and associated Exceptions in Section 2.4.1. E =f(E_v; E_h) (defined in Section 12.4.2) is combined with the effects of other loads, the following seismic load combinations is applied.

Where the seismic load effect with overstrength, E_m = f(E_v; E_mh), defined in Section 12.4.3, is combined with the effects of other loads.