OPTIMIZATION BASED ON COMPARISON BETWEEN COMPOSITE I BEAMS AND COMPOSITE U BEAMS

摘要

Based on the optimization design of the traditional steel-concrete composite I beam, a new kind of beam—the concrete composite beams encased with steel ("composite U beam" in this paper) is designed. Both composite beams are designed in accordance with China code under the conditions of the ultimate and the serviceability limit states. To find out the spans and loads, at which the new composite U beam structure shows its improvements and advantages, a comparison between composite I beams and composite U beams is carried out for simply supported beams of different spans and different loads. The optimization was performed by the penalty function method to solve the constrained nonlinear programming (NLP) problem, which is more precise than that with traditional structural analysis. At the end of the paper, some contour diagrams are shown, which can be referred for the researchers and the engineers. The results show that this new composite U beam can be applied into the engineering.