Shaking table experiment study of a multi-tower cable-stayed bridge with consideration of seismic pounding effect between the main bridge and approach bridge

Abstract

In this study, a 1/100-scale shaking table experiment was designed and conducted for a multi-tower cable-stayed bridge in order to investigate its seismic response characteristics with consideration of seismic pounding between the main and approach bridges. The test parameters include the expansion gap size and period ratio between the main bridge and the approach bridge. Both the near-field and far-field ground motions were selected to excite the model. Test results indicate that the seismic response of multi-tower cable-stayed bridges is very sensitive to the gap size and a reasonable gap size of expansion joint can mitigate the pounding effect on structural response. In addition, a period ratio close to 2:1 resulted in the most significant pounding effect and should be avoided in the design stage to reduce the collision risk. Moreover, seismic pounding could significantly amplify the relative displacement between the pier and girder of the main bridge elevating the risk of girder unseating. The test results can provide a valuable reference for the seismic design of cable-stayed bridges with multi-tower.