考虑体系弯扭非线性的异型桥梁地震最不利输入方向及易损性研究

近年来，外形独特、造型美观的异型桥梁发展迅速，与此同时结构形式以及传力途径的复杂性导致其结构体系呈现出较高的弯扭耦合非线性行为，目前对于异型桥梁减震体系的最不利输入方法及地震易损性分析研究开展较少，这些都为异型桥梁的安全留下隐患。为此，本项目以三类异型桥梁（异型梁桥、异型拱桥和异型缆索桥）为主要研究对象，采用改进反应谱法确定异型桥梁地震动最不利输入方向并实现易损性分析，主要内容包括：（1）研究考虑体系弯扭非线性的异型桥梁动力特性；（2）研究确立异型桥梁减震体系最不利输入方向的改进反应谱方法并通过结构最大输入能量验证其合理性；（3）研究异型桥梁的合理地震动强度指标，考虑动轴力变化的异型桥梁构件能力概率模型，开展异型桥梁体系易损性分析；（4）进行异型桥梁多台阵振动台试验，验证有限元模型与理论分析方法的有效性。研究成果可为异型桥梁减震体系的设计方法、地震易损性分析提供重要的理论支撑。

In recent years, special shaped bridges are massively constructed because of their aesthetic appearance. Special shaped bridges are susceptible to strong motion due to the complexities of structural type and force transforming route. There is limited work on the critical incidence angle and seismic vulnerability analysis of isolated special shaped bridges, which leads to potential threats to these bridges. Thus, this project focus on three types special shaped bridges, i.e. special shaped girder bridge, special shaped arch bridge and special shaped cable supported bridge. An improved response spectrum method is used to determine the critical input angle of these special shaped bridges, and seismic fragility of the bridges is analyzed. The main contents are as follows: (1) observation of the dynamic characteristics of special shaped bridge with consideration of system bending and torsion nonlinearity (2) establishment of the improved response spectrum method used for determining the critical input angle of isolated special shaped bridge, and this method is validated by the maximum energy of the bridge. (3) research on the appropriate intensity measure(IM), the component probabilistic capacity model with varying gravity force, and the system fragility of special shaped bridge. (4)conducting shaking table test with multi-tables, which can be used for verifying the rationality of finite element model and theoretical methods. The research outcomes can provide support for seismic analysis , seismic vulnerability estimation and isolation design of special shaped bridge.