SEISMIC PERFORMANCE OF STEEL BUILDINGS WITHVERTICAL IRREGULARITIES BY LINEAR AND NONLINEARANALYSES

Seismic responses of two ۱۲-story steel buildings with specific vertical irregularities werecompared with those of a regular building of the same size, by employing non-linear time historyanalyses (NLTHA). The three considered buildings possessed the same architectural space and wereassumed to be located within a high seismic hazard zone. Three site classes of stiff, medium, and softwere considered, and in all nine cases, the buildings’ structures were designed by LRFD, usingequivalent linear static and pseudo-dynamic methods for their analysis. Subsequently, sevenaccelerograms with different frequency characteristics were chosen, and NLTHA was conducted tostudy plastic hinges (PHs) formation and inter-story drifts. Results revealed that, due to irregularity,number of PHs, exceeding the Collapse Prevention performance level, could reach approximately ۶۰%of the total PHs, and that the drift ratio might reach a maximum value of ۳%. On this basis, AISCprovisions seem to need some revisions

کلیدواژه ها:

Nonlinear Time History Analysis (NLTHA) ، Equivalent Linear Static and Pseudo-Dynamic Methods ، Irregular Buildings