System Reliability Evaluation of Ductile Frame Structures

Abstract

The system reliability evaluation of ductile frame structures presents two difficulties. One is the identification of significant failure modes; the other is the computation of overall failure probabilities contributed from these significant modes. In this paper, a practical procedure is developed, in which a failure mode independent performance function is defined using load factor obtained by limit analysis, and a response surface approach is used to approximate the performance function. With the performance function of explicit second-degree polynomial, the failure probability can be readily obtained using First and Second Order Reliability Method (FORM/SORM). Several examples are investigated, and it is found that the obtained response surface is a good approximation of the inner connotative surface of the limit state surfaces of the structural system. The proposed procedure has good efficiency and enough accuracy for system reliability evaluation of ductile frame structures. The difficulty in both failure mode identification and failure probability computation can be avoided by using the proposed procedure.