冲刷腐蚀下桥梁的地震风险分析

SEISMIC RISK ANALYSIS UNDER SCOUR CORRODED BRIDGES

沿海桥梁在使用过程中,由于水流冲刷和氯离子侵蚀等环境因素影响,桥梁的材料性能会随着使用年限的增加而逐渐退化,以及土体对桩基约束下降,其抗震性能随之降低。概率性地震危险性分析方法是把地震发生的可能性当成随机事件,地震参数为随机变量,用超越概率表示其结果,概率性危险性分析主要用于建筑结构的抗震设计,确定性危险性分析常用于重要工程或特殊工程建设中。文中依托背景工程采用概率性危险性分析方法对沿海桥梁在4种冲刷深度与4种腐蚀程度进行地震风险分析,分析表明在各个破坏等级上桥梁的地震风险概率随着冲刷深度和腐蚀程度的增加而增大,且纵桥向的地震风险概率大于横桥向的地震风险概率。

In the service process of coastal bridges,the performance of various materials gradually deteriorate with the increase of service life,and the seismic performance will also decrease due to the influence of environmental fac⁃tors such as water flow erosion and chloride ion erosion.Probabilistic seismic risk analysis method regards the possi⁃bility of earthquake occurrence as a random event,seismic parameters as random variables,which expresses the re⁃sult with transcendent probability.Deterministic risk analysis is a method which assumes earthquake as determinis⁃tic event and makes statistical analysis of earthquake information.Probabilistic risk analysis is mainly used in the seismic design of building structures,while deterministic risk analysis is often used in the construction of important or special projects.In this paper,the probabilistic method is used to analyze the seismic risk of the coastal bridge in four kinds of erosion depth and four kinds of corrosion degree through a practical bridge.The analysis shows that the seismic risk probability in each failure level increases with the increase of the erosion depth and corrosion degree,and the longitudinal seismic risk probability is greater than that of the transverse seismic risk probability.