Assessment of rubber-sliding isolator effect on progressive collapse of bridges

The response of bridges to abnormal loads have always been significant in structural engineering, especially in progressive collapse analysis. In this paper, the performance of bridges, undergoing progressive collapse, with and without isolator is investigated. Nonlinear time history analysis is used to obtain maximum responses of the structure by considering two different damage scenarios. In the first scenario, it is supposed that the side column of the bridge is collapsed and therefore is detached from the structure while in the second one, the middle column is removed. Accordingly, several models with rubber-sliding isolators, designed according to AASHTO standards are analyzed using OpenSees software. Moreover, the friction parameter of the isolator is considered as a variable in terms of the sliding velocity and acting vertical load. Results show that isolator yield doesn’t occur in both scenarios and subsequently the sliding of the bridge deck is not observed. However, a permanent displacement in the first scenario is detected because of instability of the bridge deck. It can also be noted that in most cases, using seismic isolators results in the growth of the maximum responses.