采用振动台阵的超大跨斜拉桥大比例全模型试验研究

强震作用下超大跨斜拉桥的结构响应与其结构体系密切相关，且受基础和场地土特性影响较大，然而目前为止，因试验条件和技术所限，尚缺乏相关的全桥模型振动台试验研究。以一座试设计的主跨1400m超大跨斜拉桥为原型，设计一座几何相似比为1/70、包括桩基础和场地土的全桥模型；采用振动台阵试验技术，研究El Centro波、人工波、Mexico City波等三种典型地震一致激励下不同结构体系的地震响应特性及影响机理，所研究的结构体系包括：纵向半漂浮体系、纵向弹性约束体系、以及本文作者提出的纵向辅助墩耗能体系和横向耗能体系；探讨不同纵向结构体系的抗震性能以及附加在上塔柱间的耗能构件对斜拉桥横向地震响应的控制效果。试验结果表明：土-结构相互作用对上部结构地震响应的影响不可忽视；主塔地震响应受高阶振型的影响明显；在PGA为0.4g以下的El Centro波和人工波、以及PGA为0.2g的Mexico City波作用下，结构响应仍处于弹性状态；纵向弹性约束体系和纵向辅助墩体耗能系可有效减小主塔位移和塔-梁间纵向相对位移响应，其中作者提出的纵向辅助墩耗能体系的抗震性能更好；附加耗能构件可有效降低主塔的弯矩应变响应，实现分散主塔受力和附加耗能作用，但对主塔加速度和位移响应的控制有限。

Experimental studies on a large-scale full model of a super long-span cable-stayed bridge by using shaking table array system

Seismic responses of super long-span cable-stayed bridges are highly dependent on the structural systems under strong earthquakes and are also affected by the foundation and site soil. Due to the limitations of facilities and technology of shaking table test, however, few experiments have been carried out on the full model of super long-span cable-stayed bridges up to now. With a trial designed super long-span cable-stayed bridge with main span of 1400m taken as prototype, a full model with pile foundation and site soil was designed with a scale of 1/70. Based on the shaking table array system, the seismic response characteristics of various structural systems under three typical earthquake inputs (including El Centro wave, artificial wave and Mexico City wave) and the influencing mechanism were investigated. The investigated structural systems include the longitudinal semi-floating system, longitudinally and elastically constrained system as well as the proposed energy dissipation system with longitudinal supplementary pier and the proposed transverse energy dissipation system. Furthermore, the seismic performance of different longitudinal structural systems and the control effects of supplemental energy dissipation components attached between the pylons on the transverse seismic response of the cable-stayed bridge were investigated. The experimental results show that: (1) the effect of soil-structure interaction on the seismic response of superstructure shall not be neglected; (2) the effects of higher order modes on the seismic responses of the main tower are evident; (3) the scaled model shall be still in the elastic stage under the actions of El Centro wave and artificial waves with PGA less than 0.4g and Mexico City wave with PGA less than 0.2g; (4) compared with the seismic performance of the floating system, the energy dissipation supplementary pier system on reducing the displacement of the main tower and the relative displacement between tower and girder were superior to those of the elastically constrained system; (5) the supplemental energy dissipation components may obviously reduce the bending moment and strain response of the tower, decentralize the inner force of the tower and dissipate earthquake input energy, but their restraints on the transverse displacement and acceleration of the tower are limited.