Seismic Behaviour of Irregular Structures

摘要

Vertically irregular buildings are frequently constructed across the globe for functional as well as aesthetic considerations. However, post-earthquake reconnaissance survey reports revealed high seismic vulnerability of buildings with vertical irregularities. Consequently, it is crucial to explore the reason behind their high seismic vulnerability in order to improve their performance during impending earthquakes. Considering the scarcity of relevant research in this regard in the existing literature, a humble effort is undertaken to comprehend the seismic behaviour of irregular structures. Several case studies comprising different configurations of irregular structures are chosen for performing response spectral as well as non-linear time history analyses. The results of the analysis indicate that the irregular structures may have lesser base shear owing to lesser mass as compared to a similar reference regular structural system. However, there is ample chance of higher stress concentration as well as higher ductility demand in the members around the irregularity. This phenomenon may trigger early damage of these members, leading to early damage propagation culminating into progressive collapse of the entire or a major part of the structure. Member strength enhancement in the vicinity of vertical irregularity may improve the overall seismic performance of the irregular structures.