An Integral Approach to Probabilistic Seismic Hazard Analysis and Fragility Assessment for Reinforced Concrete Frame Buildings

Abstract

Fragility curves are useful tools for presenting the risk of structural damage from earthquakes as a function of a ground-motion parameter. Seismic hazard analysis for an area precedes the fragility analysis for structures built in that area. Many studies are available in the literature regarding probabilistic seismic hazard analysis (PSHA) and fragility estimation. However, a practical approach to integrate the hazard curve from PSHA and using the ground motion of that level to estimate fragility can be an area to explore further. In this study, an effort has been made to obtain peak ground acceleration (PGA) level at design-based earthquake (DBE) from PSHA. Based on this PGA value obtained, a fragility assessment has been performed. This study aims to obtain a fragility curve for a midrise RC frame building for DBE hazard level using PSHA. Three 6-story RC frame buildings are considered in this study for a seismically active zone in India. The buildings have been designed with the following performance objectives: (1) immediate occupancy (IO) with 1% drift, (2) life safety (LS) with 2% drift, and (3) collapse prevention (CP) with 3% drift. Incremental dynamic analysis (IDA) is performed using 22 numbers of far-field ground motions as prescribed by a strong ground-motion database to obtain the capacity of exceeding the respective drift limit states. Fragility curves for the three buildings are generated based on those capacities. The present study is a practical approach to capture the consequence of seismic hazard for an area and predicting the seismic risk.