Reliability-based design optimization for the structures with fuzzy variables and uncertain-but-bounded variables

A study was conducted to demonstrate direct reliability-based design optimization (DRBDO) for the structures with fuzzy variables and uncertain-but-bounded variables. An approach called target performance-based approach (TPBA) was developed to address the problems associated with DRBDO. The proposed TPBA was obtained by a numbered of equations that were motivated by the performance measure approach (PMA) for probabilistic RBDO and the concerned performance-based approach (CPA) for nonprobabilistic RBDO. The similarities were that they were based on the equivalence between reliability index constraints and target performance constraints. TPBA was applied to the situation with fuzzy variables and uncertain-but-bounded variables, whereas PMA and CPA were applied to random variables and nonprobabilistic framework.