A Hybrid Method for Structural System Reliability-Based Design Optimization and its Application to Trusses

Most research studies on structural optimum design have focused on single-objective optimization of deterministic structures, while little study has been carried out to address multi-objective optimization of random structures. Statistical parameters and redundancy allocation problems should be considered in structural optimization. In order to address these problems, this paper presents a hybrid method for structural system reliability-based design optimization (SRBDO) and applies it to trusses. The hybrid method integrates the concepts of the finite element method, radial basis function (RBF) neural networks, and genetic algorithms. The finite element method was used to compute structural responses under random loads. The RBF neural networks were employed to approximate structural responses for the purpose of replacing the structural limit state functions. The system reliabilities were calculated by Monte Carlo simulation method together with the trained RBF neural networks. The optimal parameters were obtained by genetic algorithms, where the system reliabilities were converted into penalty functions in order to address the constrained optimization. The hybrid method applied to trusses was demonstrated by two examples which were a typical 10-bar truss and a steel truss girder structure. Detailed discussions and parameter analysis for the failure sequences such as web-bucking failure and beam-bending failure in the SRBDO were given. This hybrid method provides a new idea for SRBDO of trusses. Copyright (c) 2015 John Wiley & Sons, Ltd.