随机地震作用下大型渡槽结构可靠性求解方法

基于混凝土连续介质损伤力学和概率密度演化理论，结合物理随机地震动建模方法和精细化有限元分析程序，建立了大型渡槽结构随机动力反应分析与可靠度评估框架。以某大型钢筋混凝土渡槽结构为研究对象，采用OpenSEES基于纤维梁单元建立其三维有限元分析模型。以工程地震动物理随机函数模型生成的100条随机地震动样本及相应的赋得概率为基础，开展该渡槽结构的随机地震反应分析，获取渡槽结构的随机动力响应。进而通过概率密度演化方法可获得结构响应的概率密度随时间涨落情况。以渡槽槽墩极限位移角响应为吸收边界条件，可获得不同给定阈值条件下渡槽结构的动力可靠度指标。所建议的分析框架和方法将为渡槽结构的抗震分析与可靠性设计提供重要借鉴。

Solution to reliability of large aqueduct structures subjected to random earthquake ground motions

This paper describes a framework for stochastic dynamic analysis and reliability assessment of large aqueduct structures that combines the continuum damage mechanics of concrete and the probability density evolution theory to model random ground motions using a refined FEM procedure. This new approach adopts a fiber beam element in OpenSEES to simulate the three-dimensional behaviors of the reinforced concrete structure of a prototype aqueduct, and generates one hundred samples of random ground motions with assigned probabilities using a physical random function model. We make a stochastic dynamic analysis obtaining the random dynamic responses of this structure and then adopt a probability density evolution method to examine the effect of random fluctuations in the responses. Dynamic reliability curves at different failure thresholds can be obtained for large aqueduct structures that are given absorbing boundary conditions associated with the ultimate displacement ratios of the piers. Thus, the framework and analysis in this study is a useful tool for seismic analysis and reliability design of large aqueduct structures.