Seismic response characteristics of a base isolated cable-stayed bridge under moderate and strong ground motions

In this study, the seismic behavior of an existing steel cable-stayed bridge equipped with lead-rubber bearing subjected to moderate and strong earthquakes is investigated. The bridge is located at high seismic zone and experienced an earthquake in 1988 which caused the failure of one of its anchorage plate of the support. Herein, the bridge was modeled in three dimensions and the base isolators implemented at the abutments and deck-tower connection. The bridge seismic responses were evaluated through nonlinear dynamic time-history analysis. The comparative analysis confirmed that the base isolation system was an effective tool in reducing seismic force transmit from substructure to superstructure. Furthermore, the overall seismic performance of cable-stayed bridge significantly enhanced in longitudinal and transverse directions. However, it is observed that the axial force of the tower in substructure increased due to the isolation system induced torsional deformation to the superstructure under transverse seismic loads.