Abstract
The shape of a structure must be determined optimally from the viewpoint of safety and economy. Especially if we have uncertainty concerning the loads or strengths, the conventional treatment which is represented by the safety factor cannot satisfy the requirement. This report proposes a method for the determination of a structural shape for the case where the structure is subjected to static loads whose magnitudes vary according to the normal probability density function and is excited by random loads which cause dynamical responses, and where the local sizes, material properties and strengths are also assumed to be random variables which are governed by normal distributions. The object of the design is to minimize the volume of the structure ; as design constraints, the probabilities of the first excursion failure and fatigue failure are taken into consideration so that they don't exceed a certain value. In the numerical treatment, an effective procedure is used in order to obtain pseudo-optimum shapes.
