纵向地震激励下倒Y形主塔斜拉桥的地震易损性分析

结合我国现役大跨斜拉桥的结构特点，以Ⅲ类场地上的倒Y型主塔斜拉桥为研究对象，选取20条实测地震波进行增量动力分析，同时将材料应变计算的截面曲率水平作为斜拉桥塔、墩、桩的损伤指标，据此求解斜拉桥塔、墩、基础等构件在不同地震动水平下超越不同损伤状态的概率，然后利用非线性拟合获得倒Y形主塔斜拉桥各构件地震易损性曲线，获得斜拉桥地震易损部位，损伤破坏过程的认识。研究表明：从各构件损伤的超越概率由高到低的排序上看，斜拉桥的主塔是最不易损的构件，而过渡墩桩基是最易损伤的构件；Y形主塔的易损部位主要集中在下塔底、中塔底、中塔顶三个部位。

Seismic Fragility Analysis of Upsidedown-Y-Shaped Tower for Long-Span Cable-Stayed Bridges under Longitudinal Excitation

The sample of cable-stayed bridge studied in this paper is based on the structural characteristics of cable-stayed bridges recently built in China. Excited by twenty ground motion waves belonging to III soil site type, the incremental dynamic analysis of cable-stayed bridge is made herein. The probabilities of different dam- age state exceedance of the main tower are studied, as well as the transition pier, auxiliary pier and the piles subjected to different ground motion level. To compare the seismic vulnerability of different components, the seismic fragility curves for different components of the sample cable-stayed bridge are developed. The research show ： for upsidedown-Y-shape tower of the cable-stayed bridge, the vulnerable zones appear often on three posi- tions, which are tower bottom, middle tower bottom, and top of the middle tower.