Vulnerability Assessment of Masonry Structures In Seismically Prone Regions of Pakistan

Abstract

The buildings can withstand earthquake more effectively if the structural performance of the existing buildings can be assessed accurately. This study aims at determining the effect of masonry as an infill on the vulnerability of reinforced concrete frame buildings by using probabilistic performance based assessment. Refined linear and nonlinear structural models were developed, from data collected through professional surveys, using PERFORM-3D platform. Nonlinear – static and dynamic - analyses were carried out, for fifteen natural ground motions, to examine the plastic behavior of the models. Subsequently, vulnerability was assessed using fragility relationships. The fragility parameters were determined by employing Maximum Likelihood Method (MLM). The results indicated decrease in the probability of exceedance of specific damage states of the structures with respect to seismic intensity for masonry infill frames. From fragility curves it is concluded that although the use of masonry as an infill temporarily enhances the capacity of Reinforced Concrete (RC) Frame buildings as the probability of exceedance for masonry infilled RC frames is significantly reduced due to the increase in overall stiffness of the structure but it restricts the ability of structure to deform which leads to localized failures.