Formulation of Economic Assessment for Optimum Design Based on Structural Reliability.

Abstract

This study deals with an economic analysis of structural systems on using a reliability-based design method. Although the expected total cost which is composed of the initial cost and the cost of failure for the structural system has been investigated, it is crucial to consider the annual prediction cost with life cycle cost (LCC) during the life duration. It is also important to evaluate the cost not only on structural failure but also on designer's faults. Furthermore, it is necessary that the cost of the reliability test is taken into account in determining the expected total cost because uncertainties of parameters are strongly dependent upon the quality control or material test. In this paper, a new expected total cost concept which includes the cost mentioned above is proposed. In the proposed formulation, an optimization problem for economic evaluation during the life duration with the capital rate of interest and rate of price fluctuations can be solved by applying the present currency and annual prediction concepts. For a comparative evaluation, from the numerical analyses of a truss bridge structure, it is pointed out that not only optimization by present value but also that by annual value is useful for decision making in practical design.