基于概率的桥梁结构地震危害性分析

Probability based seismic risk analysis of bridge structures

在考虑结构能力和地震作用下结构需求两个方面的不确定的基础上提出一个基于概率的桥梁结构地震危害性分析方法。该方法把基于概率的地震危害性分析这个复杂的问题,在全概率理论的基础上分割成为地震危险性分析、结构的地震响应分析和破坏与损失分析3个主要的步骤,且地震危害性分析的构成被认为是在参数之间的条件概率是独立的和离散的Markov过程,进而在严格的和一致的状态中推导结构在特定地震危险性水平下的年平均达到或超过指定极限状态的解析表达式。另外,通过提出的方法对一个三跨连续刚构桥结构在特定地震环境下的地震危害性进行研究,结果表明该方法对桥梁结构的地震危害性分析具有适用性,是一种评价地震作用下桥梁结构性能的有效工具。

A method for probabilistic seismic risk assessment （PSRA） of bridge structures is developed, considering the uncertainty of structural capacity and seismic demand. The framework utilizes the Total Probability Theorem （TPT） to divide the complicated problem into three main stages： seismic hazard analysis, structural analysis and damage analysis. the framework assumes that these stages are independent and discrete Markov processes, where the conditional probabilities between parameters are independent, making it as a robust methodology for performance-based earthquake study of the logical elements of the processes in a rigorous and consistent manner. An analytical expression is presented based on total probability theory to describe the mean annual rate of structural performance level reaching or exceeding a specific limit state, and the analytical solutions are adopted to analyze the seismic risk of a three-span stiff-frame bridge in a specific hazard environment,the result of which shows that the recommended method is applicable for seismic risk analysis, and PSRA is an effective tool for assessment of the seismic performance.