Seismic vulnerability assessment of isolated bridges subjected to environmental deterioration

This study focuses on the evaluation of the vulnerability of isolated bridges subjected to environmental deterioration during their service life. Two types of devices were considered, one made with natural rubber (NR) and one with high damping rubber (HDR). A stochastic deterioration model was adopted, using Markov-Chain simulations, to estimate the materials property variation inside the bridge devices. Then fragility curves of the deteriorated bridge were computed via non-linear dynamic analyses developed with OpenSees, taking into account the increased stiffness of the isolating system. Results obtained from this work show that, for each level of damage, the deterioration process of the seismic devices determines an increase of the seismic vulnerability of the structure. In addition, the stochastic approach allows a proper estimation of the variation of the bearing stiffness during the bridge service life.