Seismic Performance Assessment of SMRF Structures Subjected to Mainshock-Aftershock Seismic Sequences by Endurance Time Method

Abstract

ABSTRACT Seismic performance of postmainshock buildings considering seismic mainshock-aftershock sequences are studied. The case studies correspond to three SAC steel MRF buildings of three, nine and twenty stories. The 2-D models are able to capture important properties of deterioration of strength and stiffness. Endurance time method is used to predict the response of structures in different hazard levels. Results are compared with those from of nonlinear incremental dynamic analysis. Maximum dynamic seismic responses of structures are captured during synthetic mainshock-aftershock seismic sequences which are produced by endurance time method. Interactional-conceptual curves for different seismic performance levels and residual collapse capacity of post-mainshock damaged buildings are presented. The collapse fragility curves of case studies are extracted. The results show that the residual seismic response of building caused by the mainshock and the direction of applied aftershocks are highly significant factors in evaluation of postmainshock buildings. It is found that in a seismic sequence which has two earthquakes with different intensities, occurrence of the stronger shake before the less intensive one, imposes higher seismic risk to the building.