Probabilistic vulnerability scenarios for horizontally curved steel I-girder bridges under earthquake loads

Horizontally curved steel I-girder bridges are located in all seismic zones in the United States. Research has shown that damage can occur to steel bridge components under earthquake loads. Probabilistic-based techniques are one tool that can be used to assess more accurately the seismic vulnerability of curved bridges for various damage states and at various seismic hazard levels. To examine probabilistic-based vulnerability criteria efficiently, the study used response surface metamodels (RSMs) in conjunction with Monte Carlo simulations to generate horizontally curved steel I-girder bridge fragility curves. The generated curves were then used to evaluate bridge damage in terms of previously published structure damage states. The use of RSMs reduces the required number of computer simulations needed to generate the fragility curves. The paper summarizes the fragility curve generation procedure for a group of horizontally curved steel I-girder bridges using RSMs in association with Monte Carlo simulation. Probabilistic vulnerability scenarios are presented via application to existing horizontally curved steel bridges located in Pennsylvania, New York, and Maryland to estimate seismic demands for those bridges and to generate fragility curves.