铁路简支梁桥三维地震易损性分析

为了评估铁路简支梁桥在近场地震作用下的抗震性能,基于OpenSEES平台建立铁路典型5跨简支梁桥的易损性分析模型。从PEER数据库选取100条地震波作为三维地震动输入样本进行非线性动力时程分析,获得不同地震输入角度对应的桥梁地震响应数据。根据桥墩弯曲破坏和支座变形破坏的损伤状态方程确定相应的损伤指标。基于结构可靠度理论,建立桥梁三维易损性分析方法,从而获得了桥墩和支座构件的三维易损性云图。由云图可以得到:桥墩和支座均在顺桥向和横桥向输入方向上最容易发生损伤。研究结果表明:在近场地震作用下,铁路简支梁桥的易损性与地震动的输入角度密切相关;桥墩和支座的易损性随地震动输入角度的变化规律具有明显的区别。基于三维易损性云图,可以给铁路简支梁桥的抗震设计和震后损伤识别提供理论依据。

Three Dimensional Seismic Vulnerability Analysis of Railway Simply Supported Girder Bridge

The vulnerability analysis model of typical five-span simply supported girder bridge is established based on the OpenSEES platform to evaluate the seismic performances of railway simply supported girder bridges under near-field earthquake action. 100 seismic waves are selected from PEER database as input samples of 3 D seismic motion, and then nonlinear dynamic time history analysis is carried out to obtain seismic response data of bridges. The damage indexes are determined according to the damage state equations of pier bending failure and bearing deformation failure. A 3 D vulnerability analysis method for bridges is established based on the theory of structural reliability, and the 3 D vulnerability nephograms of piers and bearings are obtained. The nephograms show that piers and bearings are most likely to be damaged in the longitudinal and lateral inputting directions. It is concluded that the vulnerability of railway simply supported girder bridges is closely related to the input angle of ground motion under near-field earthquake action, and the change rules of piers and bearings' vulnerability are obviously different with the changes of the input angle of ground motion. The 3 D vulnerability nephograms obtained can be used to provide theoretical basis for the seismic design and post earthquake damage identification of railway simply supported girder bridges.