Building portfolio seismic fragility analysis: incorporating building-to-building variability to carry out seismic fragility analysis for reinforced concrete buildings in a city

Abstract

Predicting how future earthquakes will affect structural performance in a particular region is a challenge due to the unpredictable nature of earthquakes and inherent uncertainties in construction materials and the geometry of structures. This study considers building-to-building variabilities as inputs in an existing Response Surface Methodology (RSM) that are based on the Design of Experiment (DoE) technique to quickly determine the structural fragility of a region. As it is impractical to analyse each individual structure in a region in detail, this study addresses the issue by collecting a set of building parameters and using screening design to evaluate the most significant building parameters in the overall seismic performance. Instead of performing building-to-building analyses, the propagation of uncertainty in building-to-building variability can now be performed using a polynomial response surface metamodel. The metamodel is a function of the response of the building, and a set of significant parameters. This study aims to obtain the fragility of a collection of buildings with the help of the existing RSM by considering variability in structural parameters that can represent the overall structural geometric and material properties within a region. A case study is conducted for the collection of reinforced concrete (RC) buildings in the city of Silchar, located in Northeast India, which is one of the most seismically active regions of the country. The fragility curve developed with significant building parameters from RSM has been compared with that of the conventional method using Incremental Dynamic Analysis (IDA), and the match of the result confirms the accuracy of fragility assessment using RSM.