Topological and Size Optimization of RC Beam Bridges: An Automated Design Approach for Cost Effective and Environmental Friendly Solutions

This work presents a procedure for the automated design and optimization of reinforced concrete beam bridges. The aim is to find solutions that minimize the investment cost and the environmental impact of the bridge. The complete structure is optimized including: number of spans, pier locations, pier-deck connections and deck dimensions. A detailed design of the deck reinforcement is included as well. Furthermore, constructability is considered and quantified within the investment cost to avoid a merely theoretical optimization. Genetic Algorithm (GA) and Pattern Search (PS) optimization algorithms are used. To reduce the computational time and make the procedure more user-friendly, a memory system is integrated and a modified version of GA is developed. In this paper, the proposed procedure is applied to re-design an existing bridge originally designed according to Eurocodes by an experienced engineer in 2013. Savings of 10-15% for both investment cost and environmental impact have been obtained. Finally, the proposed procedure has been applied to several alternatives with different total bridge lengths to suggest the optimal number of spans for a given total bridge length.