结构失效模式可靠度指标对随机变量的敏感性分析

Sensitivity analysis of reliability index of failure modes to random variables

首先用基于响应面的随机有限元法来获得失效模式上各个单元的极限状态方程,然后用逐步等效线性化法获得该失效模式的等效线性化极限状态方程,从而可以很方便地用失效模式的可靠度指标对随机变量的敏感性进行分析.对一个碾压混凝土重力坝的3个层面进行了分析,数值算例显示,应用Mohr-Coulomb准则时,失效模式的可靠度指标对抗剪断粘聚力最为敏感;抗滑稳定可靠度指标对抗剪断摩擦系数的变异系数非常敏感,而对于抗剪断粘聚力的变异系数不太敏感.算例表明该方法对于大型、复杂结构的随机变量的敏感性分析是有效的.

Sensitivity analysis of reliability index to random variables is proposed in the paper. Firstly, stochastic finite element method （FEM） based on response surface is suggested to get a set of limit state functions of failure elements of a failure mode; and then a set of equivalent linear equations for these functions is obtained; finally, it is convenient to evaluate sensitivity of reliability index of failure modes to random variables. While three failure modes of roller compacted concrete gravity dam are computed; numerical example shows that reliability index of failure modes is most sensitive to shearing strength parameter cohesion c＇, and the suggested approach is efficient and applicable.