桥梁系统地震多维易损性分析  

MULTI-DIMENSIONAL FRAGILITY ANALYSIS OF BRIDGE SYSTEM UNDER EARTHQUAKE

作　　者：王其昂[1] 吴子燕[1] 贾兆平[1] 

机构地区：[1]西北工业大学力学与土木建筑学院,西安710129

出　　处：《工程力学》2013年第10期192-198,共7页Engineering Mechanics

基　　金：国家自然科学基金项目(50878184;50875212;51278420);西北工业大学研究生创业种子基金项目(Z2012059)

摘　　要：综合考虑地震地面运动以及性能极限状态的不确定性,提出了基于多地震需求参数分析的桥梁系统易损性评估方法,将易损性概念从一维扩展到多维。该方法首次提出服从多元对数正态分布的概率地震需求模型探讨桥梁体系各构件响应相关性,同时考虑各构件性能极限状态的相关性建立多维性能极限状态方程,确定结构失效域,通过Monte Carlo模拟计算系统多维地震易损性。以某一钢筋混凝土多跨连续梁高速公路桥为算例,通过非线性动力分析法获得最大响应样本,利用最大似然估计求得概率地震需求模型未知参数,计算体系多维易损性,并与构件易损性相比较。结果表明:桥梁体系多维易损性较构件易损性偏大,可避免用单一构件易损性代替系统易损性产生的非保守估计,预测结果更利于工程安全,为桥梁修复加固和交通系统可靠性分析提供理论依据。A multi-dimensional fragility evaluation methodology for bridge is proposed based on multiple seismic demand parameter analysis. The method incorporates uncertainties in ground motion and performance limit state （PLS） and extends the definition of fragility to demand model （PSDM） accorded with multivariate multi-dimension problems. A novel probabilistic seismic lognormal distribution is addressed to discuss the dependencies of various component responses. Considering the correlation of component PLS, the generalized multi-dimensional PLS function is established. Finally Monte Carlo simulation is performed to calculate the fragility of system. A multi-span continuous reinforced concrete girder bridge is used as an example to illustrate the approach. The samples of maximum responses are obtained through nonlinear dynamic analysis to calculate the maximum likelihood estimators of unknown parameters in PSDM, then the system fragility curve is developed and compared with individual component fragility. The result shows that multi-dimensional fragility of bridge is higher than component fragility, thus eliminating non-conservative estimation resulting from substituting the component fragility for system. The proposed method will better ensure the safety of structures, providing theoretical evidence for bridge retrofit and reliability analysis of transportation network.

关 键 词：桥梁工程 多维易损性 多维性能极限状态 概率地震需求模型 非线性动力分析 可靠性分析 

分 类 号：TU318[建筑科学—结构工程]