强震作用下城市连续高架桥倒塌失效模式

高烈度地震区内城市高架桥梁结构是城市交通的命脉,但当其遭遇强震导致失效时会造成不可预估的社会后果.高架桥或者其构件发生损伤导致自身不能发挥正常的使用功能时认为桥梁失效.以某六跨连续梁高架桥为工程背景,采用OpenSees软件建立了三维非线性有限元计算模型,基于增量动力分析(incremental dynamic analysis,IDA)法和加权秩和比法来判别在强震作用下该高架桥在的连续倒塌失效模式.计算过程中考虑支座的摩擦滑移,根据损伤值的变化来判断构件的状态,对连续梁桥各个构件的失效次序进行统计,给出具有统计意义的地震倒塌失效模式和最弱失效模式.结果表明:根据加权秩和比法得到的倒塌失效规律和最弱失效模式基本一致,首先是起到摩擦减震的滑动支座失效,其次是固定墩和固定支座失效,最后非固定墩失效.研究结果可为类似连续梁高架桥的抗震分析和地震失效倒塌模拟提供一定的参考和借鉴.

Study on collapse failure mode of urban continuous viaduct under strong earthquake

When the viaduct or its components are damaged and fail to function normally, the bridge is considered to be invalid. Taking a six-span continuous beam viaduct as the engineering background, a three-dimensional nonlinear finite element calculation model was established by OpenSees software. Based on IDA analysis method and weighted rank sum ratio method, the continuous collapse failure mode of the viaduct under strong earthquakes is identified. The friction slip of bearing is considered in the calculation process, the state of the component is judged according to the change of the damage value, the failure sequence of each component of the continuous beam bridge is counted, and statistically significant failure modes and weakest failure modes are given. The results show that the failure mode based on the weighted rank sum ratio method is basically the same as the weakest failure mode. First is the failure of the sliding support that acts as friction damping, followed by the failure of the fixed pier and the fixed bearing, and finally is the failure of the non-fixed pier. The research methods and conclusions in this paper can provide some reference for the seismic analysis and earthquake failure collapse simulation of similar continuous beam viaducts.