Full-Model Shaking Table Tests of Seismic Behavior of a Super-Long-Span Cable-Stayed Bridge with Pile Foundations

摘要

A cable-stayed bridge is a very competitive structural type owing to its aesthetic shape, structural efficiency, and spanning ability. Pile groups are an often-used foundation type in China, even for the piers and towers of long-span cable-stayed bridges. The seismic behavior of a bridge depends on its structural system type. The soil, pile foundation, and structure interaction is a significant influencing factor, especially for flexible structures such as super-long-span cable-stayed bridges. However, experimental studies on long-span cable-stayed bridges with pile foundations are scarce. In this study, a full-model shaking table test of a super-long-span cable-stayed bridge was conducted. The 1/70-scale model, which is of a preliminary-design cable-stayed bridge with a central span of 1,400 m, includes both superstructures and pile group foundations embedded in artificial soil contained in laminar shear boxes. The full model was subjected to a suite of ground motions in the longitudinal direction by using a shaking table array. The seismic performance of the bridge model with three types of structural systems-a floating structural system, elastically constrained structural system, and supporting pier structural system-was investigated experimentally. The experimental results show that the effects of the supporting pier structural system on reducing the longitudinal relative displacement at the tower top as well as between the tower and girder are superior to those of the elastically constrained structural system and floating structural system. However, the seismic demands of the supporting piers designed as sacrificial components increase noticeably. Moreover, the dynamic characteristics of the full model obtained from the numerical simulation are in good agreement with the experimental counterparts.