Reliability Analysis of Redundant Ductile Structural Systems

A practical method for determining the point estimate of the collapse probability of ductile structural systems, particularly, plastic frameworks and trusses is developed. In addition to the assumption that classical simple plastic method of analysis is applicable, the magnitudes of loads and the component resistance capacities of a structure are assumed to be stochastic with known distributions (e.g., normal). The first step of the proposed method of analysis is to identify the major collapse mechanisms. This step is transformed into an unconstrained nonlinear minimization problem and Hooke and Jeeves pattern search was adopted as the solution technique. Once the major mechanisms are identified, their corresponding performance functions may be developed through the principle of virtual work, from which the individual mechanism collapse probabilities are calculated. The system collapse probability is then evaluated through the method of PNET. Results of the propose~ method showed good agreement with corresponding Monte Carlo calculations for a wide variety of example problems examined.National Science Foundation Grants ENG 77-02007 and PFR 80-0258