斜拉桥H型混凝土桥塔的有限延性

Limited Ductility of H-Shaped Cable-Stayed Bridge Tower

摘要:

由于塔梁之间的横向约束，在强地震动作用下斜拉桥的桥塔将产生较大的横向动力响应，为了满足规范规定的抗震性能目标,则须采用较大的桥塔配筋率.同时,桥塔基于弹性设计的思路，还会导致下部结构的工程量增加，其工程经济性值得商榷.为此采用IDA(incremental dynamic analysis)方法研究斜拉桥桥塔横桥向塑性变形分布规律和破坏模式.通过有限元分析和拟静力试验相结合的手段,对H型混凝土桥塔横向破坏机理进行验证，确定所要达到的性能目标,并得到与之对应的可以量化的性能指标.为斜拉桥的有限延性抗震设计提供理论和试验基础.

Abstract:

Large transverse dynamic responses will occur in the tower columns due to the lateral restriction between the tower and the main girder of the cable stayed bridge subjected to strong ground motions. In the current seismic design of cable-stayed bridges, a larger reinforcement ratio in tower columns is consequently needed to achieve the target seismic performance, leading to the increase in the number of the piles and its reinforcement ratio as well, whose engineering efficiency is therefore questionable. An incremental dynamic analysis(IDA) was conducted to study the lateral elastic-plastic perform and damage mechanism of the H-shaped concrete tower. The finite element analysis and quasi-static test were conducted to verify the IDA result and investigate the limited ductility of the tower in resisting the earthquake and to find out the reasonable performance objective and index.