Seismic fragility analysis of concrete bridges subjected to far- and near-field records

Near-field (NF) and far-field (FF) ground motion records were used to develop seismic fragility curves at different damage states for a multi-span reinforced concrete bridge using incremental dynamic analysis (IDA). The use of different methods for the prediction of the fragility curves, including truncated IDA, was also investigated. The results indicated that the median spectral acceleration causing different states of earthquake damage was lower for the NF records than for the FF records. In other words, the studied bridge was more vulnerable when subjected to NF records. The significantly larger probabilities of failure at different damage states, especially at the bar buckling damage state, for the case of NF records was attributed to the significantly larger variability of the results compared with the case of FF records. The results also showed that the probability of failure at different damage levels was relatively low for the case of the FF ground motions. It was also found that truncated IDA could be used to predict the fragility curves with sufficient accuracy for the cases studied.