Equivalent Period Characterization Of Performance-based Seismic Designed RC Frame

Some empirical relationships for non-seismic design RC structures are now used in several design codes to relate the fundamental period to the height of a building. These relations are mostly dealing with the structures which were built before 1980s. Such relationships, however, are not suitable for the Pushover Analysis Method. For the Pushover Analysis Method, equivalent period of a nonlinear structure plays a more important role than the elastic fundamental period. Displacement-based earthquake loss assessment method, DBELA, for instance, employs yield and limit state (secant) periods in order to come up with yield or limit state displacements.This study focus on seeking a physically sound yield period-height formula for performance based frame structures. Distributed-plasticity FE models of RC-frame structures of varying height have been developed in SeismoStruct software and the equivalent period has been derived from Displacement-based Adaptive Pushover (DAP) analyses. The derived formula has been compared with that of the previous studies, which were concentrated on the equivalent period–height relationship for existing non-seismic design frames. As expected, the equivalent period relation in this study is found more suitable for the existing RC-frame structures.