For the purpose of analysing the seismic vulnerability of bridges, through seeking the statistical property of material uncertainty to simplify the analysis, two kinds of simplified seismic vulnerability analysis methods were proposed.Aiming at a certain kind of beam bridges, which is the most widely used in practical projects in China, the Latin hypercube sampling was adopted for the uncertainty composite of bridge structure materials.Ten natural ground motions were chosen to analyse a three dimensional finite element model of the bridge.The results of the two kinds of simplified seismic vulnerability analysis methods and the conventional method were compared by using the existing statistical regularity of the structure main material.The results show that the exceeding probability of the bridge seismic structure demands over the bridge performance level calculated by the first simplified seismic vulnerability analysis method, is less than that by the traditional method,which may tend to be unsafe compared to the traditional method.The seismic fragility curves calculated by the second simplified method are closer to those by the traditional method, which means to be much safer compared with the first simplified method.The number of analysis samples will be reduced significantly when the second simplified method is taken , which could be used to estimate the seismic damage state probability of bridge structures.%为了研究简化的地震易损性方法在桥梁中的应用,通过寻求材料不确定性的统计规律,达到简化易损性分析的目的,提出了两种易损性简化分析方法.针对我国实际工程中应用最为广泛的某梁式桥梁,采用拉丁超立方抽样来进行结构材料不确定性组合,对桥梁的三维有限元模型,选用了10条天然地震动,利用结构主要材料既有的统计规律,对比研究了两种易损性简化分析与常规基于位移的地震易损性分析方法的计算结果.研究结果表明:采用简化分析方法一得到的桥梁结构地震需求超过其性能水平的超越概率要小于常规基于位移的地震易损性分析方法的计算结果,其结果偏于不安全,而且有一定的误差;采用简化方法二绘制的易损性曲线比简化方法一绘制的易损性曲线更接近常规方法的,其误差更小,其分析结果偏于安全;采用简化分析方法之二,将大幅减少分析样本数量,在实际工程中可以用来对桥梁结构地震破坏状态概率进行近似估计.
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