Adaptive simulation for system reliability analysis of large structures

This article proposes an efficient simulation-based methodology to estimate the system reliability of large structures. The proposed method uses a hyb rid approach: first, a probabilistic enumeration technique is used to ident ify a significant system failure sequence. This provides an initial samplin g domain for an adaptive importance sampling procedure. As further simulati ons are performed, information about other significant sequences is incorpo rated to refine the sampling domain and to estimate the failure probability of the system. The adaptive sampling overcomes the restrictive assumptions of analytical techniques, yet achieves the robustness and accuracy of basi c Monte Carlo simulation in an efficient manner. In this article, the propo sed method is implemented using the ANSYS finite element software, and is a pplied to the system reliability estimation of two redundant structural sys tems, a six-story building frame and a transmission tower. Both ductile and brittle failure modes are considered. The method is structured in a modula r form such that it can be easily applied to different types of problems an d commercial software, thus facilitating practical application. (C) 2000 El sevier Science Ltd. All rights reserved.