基于响应面法的混凝土桥梁时变可靠度分析

Timedependent Reliability Analysis of Concrete Bridges Based on Response Surface Method

摘要:

为了求解劣化环境作用时混凝土桥梁的时变可靠度,建立了基于改进响应面法和确定性的混凝土桥梁退化过程分析方法相结合的混凝土桥梁时变可靠度分析方法.利用FORTRAN 95分别编写了混凝土桥梁耐久性分析程序CBDAS和可靠度分析程序PIRSM.以一座预应力混凝土简支梁为对象,分析了不同极限状态下结构力学性能指标的可靠度随时间的演变过程,结果表明,混凝土正应力的可靠度指标由成桥时刻的2.16减小到成桥100年后的0.82,预应力混凝土桥梁在正常使用极限状态下的力学性能指标更有可能出现耐久性不足的情况.提出的时变可靠度计算方法克服了复杂体系结构极限状态方程通常是隐式的问题,实现了混凝土桥梁时变可靠度的求解目标.

Abstract:

In order to solve timedependent reliability of concrete bridges exposed to harsh environments,a computational methodology was developed with an improved response surface method and a deterministic degradation process analysis method of concrete bridges.Analysis programs named concrete bridge durability analysis system (CBDAS) and probability index by response surface method (PIRSM) were compiled by FORTRAN 95.The numerical method was implemented to a prestressed concrete simply supported bridge.The variations of various reliability indices in different limit states were analyzed.The results show that reliability index of concrete stress changes from 2.16 at completion 0.82 after 100 years.Mechanical property indices in serviceability limit state of prestressed concrete bridges may even suffer durability problems.The objective of timedependent reliability of concrete bridges is realized with the proposed computational methodology by overcoming the problem that the limit state equation of complex structure is always implicit.