Load and resistance factor design (LRFD) is used as the basis for nonlinear response analysis acceptance criteria specified in ASCE/SEI 7. The LRFD equations in ASCE/ SEI 7 were updated to be consistent with the equations developed for PEER/TBI (2017).
These equations were developed to provide a specific conditional probability of failure caused by risk-targeted maximum considered earthquake ( ) shaking hazard. The earthquake importance factor, , is included in the formulation of the LRFD equations to provide conditional probabilities of failure consistent with those specified in ASCE/SEI 7, Table 1.3-2.
For any nonlinear analysis including earthquake effects, gravity loads are applied to the model first followed by the application of the earthquake ground motions. Given the low likelihood of peak gravity loads occurring at the same time as shaking, realistic gravity loading should be used in the nonlinear response history analysis. Requirements for these combinations are provided in ASCE/SEI 7.