Minimum weight design with structural reliability

Abstract

A procedure is proposed for designing a structure with minimum weight and desired reliability . Simple techniques are presented for the determination of the desirable probabilities of failure, the resulting factors of safety, and the minimum weight designs of the components of the structure. An elementary analysis indicates that the over-all minimum weight is approached when the individual probabilities of failure of the components of the structure are made proportional to their weight. Probabilities of failure are thus established and transferred to equivalent factors of safety based upon the distributions (mean values and variabilities) of the applied and failing stresses. These can be determined by the distributions of the independent random variables and from criteria such as static tension, creep, fatigue, and stability, which are assumed or established from test data. Minimum weight designs are then determined by available techniques. A simple iterative scheme is employed, since the weights of the components have to be determined. The design techniques are illustrated by a simple truss example.