An alternative pushover analysis procedure to estimate seismic displacement demands

An alternative pushover analysis procedure is proposed to estimate the peak seismic lateral displacement demands for building structures responding in the nonlinear range. As compared with other pushover analysis procedures, the main advantage of the proposed procedure is that the effects of higher modes on the lateral displacement demands are lumped into a single invariant lateral force distribution that is proportional to the total seismic masses at the floor and roof levels. The applicability and validity of the proposed procedure, which is referred to as the Mass Proportional Pushover (MPP) procedure, are critically evaluated through comparisons with multi-degree-of-freedom nonlinear dynamic time-history analysis results for a set of benchmarked three-story, nine-story, and twenty-story steel moment resisting building frame structures. The estimated demands are also compared with results from a Modal Pushover Analysis (MPA) procedure. The comparisons demonstrate that the proposed Mass Proportional Pushover procedure provides, on average, better roof and floor lateral displacement demand estimates than the Modal Pushover Analysis procedure. The improvement from the proposed procedure is larger for the nine-story and twenty-story structures than the improvement for the three-story structure and is also larger for the Design Basis Earthquake (DBE) ground motion set than the Maximum Considered Earthquake (MCE) set.