An approach to multicriteria fuzzy optimization of a prestressed concrete bridge system considering cost and aesthetic feeling

In practical structural design problems, the designer should take into account several objectives, such as economics, safety, serviceability, aesthetic feeling and so on, and relative evaluations among these different characteristic objectives have some tolerances or fuzziness. For these reasons, the practical optimum structural design process concerning multiobjectives can be defined as a kind of compromising optimum decision-making process with fuzziness. In this paper, a rational, systematic and efficient fuzzy optimum design method for structural systems is developed by combining a suboptimization concept and fuzzy decisionmaking techniques at the discrete combinations of common design variables. The design method is applied to an optimum design problem of a large scale prestressed concrete bridge system considering two objectives; the total construction cost and aesthetic feeling. The rationality, the systematic design process and the efficiency of the proposed method are demonstrated.