This study deals with the optimal design of prestressed concrete box girder bridges. The optimization algorithm including the determination of an initial geometric section data which are arbitrary in the most cases of optimal design is developed to minimize the cost of superstructure. The determination of an initial geometric section data is based on an evolutionary procedure, developed recently by Xie and Steven(1993), in which the low stressed part of a structure is removed from the structure step-by-step until an optimal design is obtained. And then, the full-optimization of prestressed concrete box girder bridges using various mathematical programming techniques with the initial data is represented.
A rejection criterion for concrete structures is presented during the evolutionary structural optimization procedure. The shape of bridges section, that gives the best possible stress state under the given load and make it possible to avoid troublesome comparing with other results from different initial data to find a global optimum solution, is obtained by the method.
By the full-optimization the most effective method for prestressed concrete box girder bridges among the various optimazation technique used is found. It is verified that the initial data are fit to the optimization problem and also considered that which is the profer set of variables in the problem.