基于截尾概率-非概率混合模型的可靠性优化算法

针对工程中截尾概率变量与非概率变量同时存在的情况,给出一种新的截尾概率与非概率混合可靠性模型。在该混合可靠性模型基础上,按照可靠性指标(RIA)法给出双层嵌套可靠性优化模型,并采用改进搜索策略后的ST-Powell优化算法在外层搜索设计变量的最优值,内层采用能保证收敛的改进的有限步长迭代法求解混合可靠性指标。数值算例表明,改进搜索策略后的ST-Powell优化算法的全局寻优性得到显著提升;改进搜索策略后的ST-Powell优化算法与改进的有限步长迭代法相结合求解双层嵌套混合可靠性优化模型的正确性得到验证,且对于非线性程度较高的极限状态函数同样能够得到满足截尾概率与非概率混合可靠性模型指标要求的最优解,并对工程结构算例具有很好的适应性。

Reliability-based optimization algorithm using hybrid model withtruncated probability and non-probability

A new hybrid reliability model is presented for the case that truncated probabilistic variables and non-probabilistic variables exist simultaneously in engineering.Based on the new hybrid reliability model and reliability index assessment (RIA) method,a nested loop hybrid reliability-based optimization model is also presented.Modified ST-Powell optimization algorithm with better search strategy is used to search the optimal values of design variables in the out-loop.Modified limit step length iteration algorithm,which can ensure convergence,is used to solve the new hybrid reliability index in the inner-loop.Numerical examples show that the global optimization rate of the modified ST-Powell optimization algorithm with better search strategy can be promoted significantly,and the validity of hybrid reliability-based optimization model searched by the algorithm presented in this paper is proved.The algorithm can obtain the optimal values for hybrid reliability-based optimization model with high nonlinear limit state function.The algorithm presented in this paper has a good adaptability to hybrid reliability-based optimization problems of engineering structure.