Comparison of pushover methods for simple building systems with flexible diaphragms

Nonlinear static (pushover) methods have become increasingly popular in seismic analysis as they allow the explicitly consideration of nonlinear structural behaviour, while retaining the simplicity of the static analysis. Even though significant advances of pushover methods have occurred in recent years, the applicability of such methods for unreinforced masonry buildings with flexible diaphragms has remained relatively unexplored. This paper investigates the accuracies of various pushover methods in predicting the peak seismic response of buildings with flexible diaphragms. The peak displacement demands of simple two-degrees-of-freedom systems, considered to represent the basic characteristics of structures with flexible diaphragms, are estimated using the N2, modal pushover analysis and adaptive capacity spectrum method, and compared against time-history analyses. The results show that pushover methods generally become less reliable when the diaphragm is made flexible. However, the modal pushover analysis appears to be the most promising.Y. Nakamura, G. Magenes, and M.C. Griffit