Experimental assessment of soil–structure interaction effects on a super long-span cable-stayed-bridge with pile group foundations

Abstract

Soil–structure interaction (SSI) plays an important role in overall structural seismic behavior. However, there is a scarcity of experimental studies evaluating the SSI effects on a full bridge including superstructure, pile foundations and site soil. This paper focused on shaking table investigations on the effects of SSI on a super long-span cable-stayed bridge model with pile groups and mixture soil modelled by using uniaxial laminar shear boxes. The cable-stayed bridge model was subjected to a series of earthquake excitations in the longitudinal direction, including white noise and various earthquake waves. The dynamic interactive behavior of the cable-stayed bridge model was explored for various shaking amplitudes and frequency components. Furthermore, the influences of the soil on the system dynamic characteristics were clarified statistically. The test results show that the SSI obviously affects the seismic response of the cable-stayed bridge model in the longitudinal direction, and corresponding accelerations of structural members are amplified. The bridge seismic response may be underestimated and misinterpreted to some extent while the SSI effects are ignored. It is, therefore, suggested that more attentions should be poured into the SSI effects when performing the seismic design of super long-span cable-stayed bridges. Moreover, the SSI effects on the bridge seismic responses decrease with the increase of shaking amplitude, and significantly change as the frequency components of the input motions vary. When evaluating the system damping ratio with the SSI, the system seismic responses may be varied to a certain degree if the soil viscous damping contribution is neglected.