基于可靠度和性能的结构整体地震易损性分析

Global seismic fragility analysis of structures based on reliability and performance

地震风险分析包括地震危险性分析、地震易损性分析和地震灾害损失评估3个方面,其中,地震易损性分析可以预测结构在不同等级地震作用下发生各级破坏的概率,因此对结构的抗震设计、加固和维修决策具有重要的应用价值。传统的结构地震易损性分析主要采用经验方法或蒙特卡洛模拟法绘制地震易损性曲线。首先介绍地震风险分析的基本原理,然后提出结构整体地震易损性的概念,针对传统方法存在的问题,将结构的可靠度方法与基于性能的抗震设计理论结合起来,提出了基于可靠度和性能的结构整体地震易损性分析方法,并采用有限元可靠度方法进行了结构地震易损性的计算。以结构的最大层间相对变形作为整体性能指标,对某5层2跨钢框架结构进行了地震易损性分析,绘制了其在不同地震作用下对应不同性能水准要求的地震易损性曲线。

Seismic risk analysis includes three aspects, i.e. , seismic hazard analysis, seismic fragility analysis and seismic loss assessment. Among the three contents, the seismic fragility analysis is very important to seismic design, retrofit and upgrading decision-making of engineering structures in that it can predict the probability of unfulfilling the prescribed levels of performance requirements under all levels of seismic actions. Traditionally, the seismic fragility curves are depicted by using empirical methods or Monte Carlo simulation methods. In this paper, the basic principles of seismic risk analysis are firstly introduced, and then, the concept of global seismic fragility of structures is put forward. To overcome the problems in the traditional methods, a new method for global seismic fragility analysis of structures is p by combing the methodologies of structural reliability with the theory of performance-based seismic design, the seismic fragility of structures is computed by way of the finite element reliability methods. Taking the maximum storey-level relative deformation of structures as a global seismic performance index, the seismic fragility is analyzed for a five-storey, two-bay steel frame structure, and the seismic fragility curves corresponding to different performance levels under three levels of seismic actions are depicted by using the proposed method.