FORM-based global reliability sensitivity analysis of systems with multiple failure modes
针对多失效模式系统，推导了基于一阶可靠性方法（FORM）的方差分解可靠性灵敏度指标表达式，无需额外模型评估即可准确估计变量重要性，适用于FORM可解的系统问题。
Global variance-based reliability sensitivity indices arise from a variance decomposition of the indicator function describing the failure event. The first-order indices reflect the main effect of each variable on the variance of the failure event and can be used for variable prioritization; the total-effect indices represent the total effect of each variable, including its interaction with other variables, and can be used for variable fixing. This contribution derives expressions for the variance-based reliability sensitivity indices of systems with multiple failure modes that are based on the first-order reliability method (FORM). The derived expressions are a function of the FORM results and, hence, do not require additional expensive model evaluations. They do involve the evaluation of multinormal integrals, for which effective solutions are available. We demonstrate that the derived expressions enable an accurate estimation of variance-based reliability sensitivities for general system problems to which FORM is applicable. • We derive FORM-based approximations of variance-based reliability sensitivities for system problems. • The sensitivities are obtained through post-processing the FORM results with no additional LSF evaluations. • The proposed expressions provide accurate approximations in problems where FORM is applicable.