中文摘要：

为了有效地分析结构系统输入变量不确定性对结构系统失效概率的影响程度，研究了对基于失效概率的矩独立重要性测度的计算，并基于单层Monte Carlo计算法和密度权重计算法，建立了准确、高效求解失效概率矩独立重要性测度的单层密度权重法。工程算例表明，与已有的计算方法相比，该方法仅需较少的模型计算量就能得到足够准确的结果，极大地提高了计算效率，且具有很好的工程适用性。

英文摘要：

To efficiently analyze the influence of the input variable uncertainty of a structural system on the system＇s failure probobility, the calculation of the failure probability based moment-independent importance measure was studied, and a single-loop density weight method for accurate, efficient calculation of the failure probability based moment-independent importance measure was weight method. Two engineering examples constructed based on the single-loop Monte Carlo method and the density for the new method demonstrate that, compared with the existing methods, the proposed method can obtain very accurate calculation results with less model evaluations. Thus it greatly improves the computational efficiency, and shows its good engineering applicability.