AN OUTER APPROXIMATIONS APPROACH TO RELIABILITY-BASED OPTIMAL-DESIGN OF STRUCTURES

We present a new formulation of the problem of minimizing the initial cost of a structure subject to a minimum reliability requirement, expr essed in terms of the so-called design points of the first-order relia bility theory, i.e., points on limit-state surfaces that are nearest t o the origin in a transformed standard normal space, as well as other deterministic constraints. Our formulation makes it possible to use ou ter approximations algorithms for the solution of such optimal design problems, eliminating some of the major objections associated with tre ating them as bilevel optimization problems. A numerical example is pr esented that illustrates the reliability and efficiency of the algorit hm.