Seismic performance assessment of isolated continuous girder bridge using endurance time analysis

Abstract

The endurance time analysis (ETA) is a dynamic pushover analysis method. By inputting an endurance time acceleration function with an intensity that gradually increases with time, the dynamic response process of the structure from the elastic state to the collapsed state can be obtained. This study selected a five-span isolated continuous girder bridge as the target structure and defined the performance levels of bridge piers and the lead rubber bearings. The seismic performance of the bridge was evaluated by the ETA method and compared with the IDA results under 20 near-field and 20 far-field ground motions. Results show that the ETA is suitable for evaluating the seismic performance of the isolated continuous girder bridge and ensure the reliability of the results while reducing the calculation amount. The results of ETA are larger than those of IDA when the bridge is subjected to far-field ground motions. However, the results are the opposite for near-field ground motions. Furthermore, when ETA is used to assess the seismic performance of the isolated continuous girder bridge, the bottom curvature of bridge piers is more suitable as the performance index than the top displacement ductility ratio of bridge piers.