Seismic fragility of continuous rigid frame bridge with unequal pier height

摘要

Using the probabilistic seismic demand analysis method, the seismic vulnerability model of a certain typical unequal pier height highway bridge in the western mountainous areas of China is created in OpenSees software. Considering the uncertainty of the earthquake and bridge parameters, by adopting sampling method, the model sample database is generated to carry out bridge seismic vulnerability analysis. In order to obtain the structural dynamic response, every model in the database is calculated by using nonlinear time history analysis by using the software such as OpenSees. The curvatures were considered as the pier damage index and relative displacement were considered to be the bearing damage index to figure out the failure probabilities of different damage states. In addition regression analysis was performed to establish the relationship between the ground motion intensity and seismic requirement of bridge components. Furthermore based on a lognormal distribution assumption and the reliability theory, the fragility curves of different damage states are obtained. Fragility curves obtained can be used to evaluate the seismic performance of unequal pier height bridges, and will provide the basis for post-earthquake damage assessment.