Seismic Fragility Assessment of a Simply Supported RC Bridge

Bridges play a prominent role in transportation, and their safety and serviceability are also a major concern for engineers with respect to life and economic stability. Majority of bridges in the world were not designed according to seismic design criterion and experienced the failure due to inadequate detailing and improper design. In the present paper, the fragility analysis of a two-span RC bridge is done as per Hazus manual. Fragility curves describe conditional probability, i.e. the risk of a structure being damaged beyond a specific damage level for a given seismic intensity or ground motion. The probability of the damage of the bridge at various damage states has been determined under DBE (Design basis earthquake) and MCE (Maximum considered earthquake) loading conditions as per IS codal provisions. The responses of the bridge namely, maximum displacement, drift and ductility demand have been determined using pushover analysis method. Pushover analysis is a prerequisite study for the seismic fragility assessment. In the pushover analysis, capacity spectrum method has been considered to determine the performance point for different loadings. The nonlinearity has been considered by assigning plastic hinges in the bridge piers while the deck has been kept as elastic. Uniform loading pattern has been considered in the pushover analysis. It is necessary to assess the performance of the bridges in future earthquakes, so that adequate safety measures can be considered. The results of the present study will be beneficial for engineers for assessment of the damage of the bridge in case of post-earthquake scenario so that adequate safety measures can be ensured to improve the seismic resilience of the bridge.