Fragility analysis of reinforced concrete shear wall buildings -

Abstract

Seismic reliability analysis requires measuring the vulnerability of a structure using specified damage indicators. Typically seismic fragility curves are used to determine potential earthquake induced damage, and can be related to estimating casualties, economic and social risks. The fragility function for a specified damage state is defined as the probability of the structure reaching or exceeding this damage state, given the occurrence of a ground motion with specified intensity measure. These curves are represented mathematically using cumulative distribution functions that describe the capacity of the structure to resist specified damage limits. These limits can be associated with several Engineering Demand Parameters (EDP) that characterize the structural system response under a specified performance level. The objective of this study is to numerically evaluate the effects of various design parameters (number of stories, wall dimensions, and reinforcement detailing) of reinforced concrete shear wall buildings on their fragility curves. To achieve this, mathematical models of the structure are developed using the open source finite element analysis platform OpenSees. Each building model is subjected to the FEMA-P695 set of Far Field recorded ground motions that are systematically scaled and response is computed using nonlinear time history analysis at each step. For every set of design parameters, a fragility curve is developed by fitting a lognormal distribution to the computed responses. Based on the results of the fragility assessments of various models, the effect of the varying design parameters on the performance of the structures is studied.