Application of evolutionary operation to the minimum cost design of continuous prestressed concrete bridge structure

This paper implements an evolutionary operations based global optimization algorithm for the minimum cost design of a two span continuous prestressed concrete (PC) I-girder bridge structure. Continuity is achieved by applying additional deck slab reinforcement in negative flexure zone. The minimum cost design problem of the bridge is characterized by having a nonlinear constrained objective function, and a combination of continuous, discrete and integer design variables. A global optimization algorithm called EVolutionary OPeration (EVOP), is used which can efficiently solve the presented constrained minimization problem. Minimum cost design is achieved by determining the optimum values of 13 numbers of design variables. All the design constraints for optimization belong to AASHTO Standard Specifications. The paper concludes that the robust search capability of EVOP algorithm has efficiently solved the presented structural optimization problem with relatively small number of objective function evaluation. Minimum design achieved by application of this optimization approach to a practical design example leads to around 36% savings in cost.