结构失效概率计算的重要方向自适应线抽样方法

首先通过算例分析线抽样方法存在的问题,对于线性问题,线抽样法的效率受抽样重要方向与最优重要方向偏离程度的影响,这种偏离程度越大,效率越低;而对于非线性问题,当抽样重要方向与最优重要方向偏离较大时,线抽样的效率和精度均严重下降,甚至得出错误的计算结果.针对线抽样存在的问题,提出一种重要方向自适应的线抽样方法.在标准正态空间中,所提方法将原点指向典型失效点的方向作为初始重要方向,通过探索性线抽样和逐步修正的方法,使得线抽样的实际重要方向逼近最优重要方向,进而使线抽样方法的精度和效率得以充分发挥.数值和工程算例均验证了改进线抽样方法的优越性.

ADVANCED LINE SAMPLING WITH ADAPTIVE IMPORTANT DIRECTION FOR STRUCTURAL FAILURE PROBABILITY

Illustrations are used to analyze the limitation of line sampling(LS)firstly.For linear limit state,the efficiency of LS is affected by the dispersion of the actual important direction from the optimal one,the bigger the dispersion is,the lower the efficiency is.For non-linear limit state,in case that the actual important direction deviates from the optimal one greatly,the efficiency and the precision of LS decrease seriously,even wrong results are obtained.For these problems of LS,an advanced LS is present...