非规则连续刚构桥地震易损性分析

Seismic Fragility of Irregular Continuous Rigid Frame Bridge

为探讨非规则桥梁的抗震性能,建立了典型非规则公路桥梁的地震易损性理论模型.考虑桥梁结构参数和地震动的不确定性,抽样生成桥梁地震易损性分析模型样本库.用Open Sees软件对模型样本库进行非线性动力时程分析,以获得结构动力响应.在研究桥墩反弯点时程曲线和桥墩曲率包络线分布特征的基础上确定桥梁构件的损伤指标.采用概率地震需求分析方法获得桥梁各构件易损性曲线,并基于一阶可靠度理论获得桥梁系统的易损性曲线.结果表明:在地震作用下,非规则桥梁支座最容易损伤破坏,桥梁系统的易损性明显高于桥梁构件的易损性;易损性曲线可用于评估非规则桥梁的抗震性能,为震后桥梁损伤识别提供依据.

To investigate the seismic performances of irregular bridges,a seismic vulnerability model for a typical irregular highway bridge was created. By considering the uncertainties of an earthquake and bridge parameters,a model sample database was generated by adopting the sampling method to carry out the seismic vulnerability analysis of a bridge. To obtain the structural dynamic responses,a nonlinear time-history analysis was carried out for the sample database by using the software Open Sees.On the basis of the research on the distribution characteristics of time-history curves of inflection point and the curvature envelope of each pier,pier and bearing damage indexes were determined. The fragility curves of dangerous bridge members were generated by using the probabilistic seismic demand analysis approach,and the first-order reliability theory was employed to generate the fragility curve of a bridge system. The research results show that bearings are easy to damage to an irregular bridge subject to an earthquake action. Compared with its members,an irregular bridge system has a high failure probability. The fragility curves obtained can be used to evaluate the seismic performances of an irregular bridge and provide an evidence for post-earthquake damage identification.