First-order second-moment approximation in reliability of structural systems: Critical review and alternative approach

Abstract

The objective of the paper is to present and discuss the methods originated from the first-order second-moment approximation that are commonly used in the reliability analysis of structural systems. The approach is formulated as an optimization problem. The consequences of this formulation and some objections concerning the methods are investigated and illustrated on the examples. The lack of uniqueness and some difficulties with error estimation are considered as the main disadvantages of the approach. An alternative approach is given for the independent random variables. The approach yields the upper and lower bounds for the structural reliability. Its application is presented in the case of the linear conditions of structural failure. It is shown that the bounds remain sometimes a sole verification of the correctness of the first-order second-moment approximation.