Discussion of 'Observations on the Reliability of Alternative Multiple-Mode Pushover Analysis Methods' by T. Tjhin, M. Aschheim, and E. Hernandes-Montes

摘要

The authors have presented their work accomplished as part of the ATC-55 project, which culminated in the FEMA 440 document. They conclude that neither of the multiple-mode pushover analysis methods examined in their paper "is able to provide consistently reliable estimates of story shears and overturning moments over the height of the buildings considered. Consequently, the robustness of these procedures for general use in evaluation and design is open to question."rnThe authors reached this conclusion by comparing seismic demands estimated by the modified modal pushover analysis (MPA) procedure (Chopra et al. 2004) and their new MPA method with the "exact" demands determined by nonlinear response history analysis (RHA). It is important to note that the modified MPArnprocedure chosen by the authors estimates the response contributions of higher modes by assuming the building to be linearly elastic, which implies an additional approximation beyond those in the original MPA procedure (Chopra and Goel 2002, 2004; Goel and Chopra 2004), referred to subsequently as the MPA procedure. The authors reported such comparisons for five building models, subjected to 11 ground motions.