Research On Section Optimization Design Of Prestressed Concrete Beam Bridge Based On Genetic Algorithm

As a kind of bridge, the prestressed concrete T-beam bridge is famous for its simple shape,excellent behavior and low high-span ratio,good structural integrity,widely used in highway bridge engineering. Genetic algorithm is a simulation of the bionics theory of biological evolution in nature algorithm. It has a peculiar ability of bionic simulation with relaxed optimal conditions and better optimization results, so its application in the field of structural optimization more and more.Today,when many designer do the common span prestressed concrete simply supported T beam design, usually reference to the existing highway bridges standard drawing, and make some appropriate revisions. So it is necessary to optimize the standard drawing design.For a great number of small and medium span bridge construction projects, the optimization design can raise great economic benefits. In this paper, choose common span prestressed concrete simply supported T beam design as the optimization object, using genetic algorithm to optimize the section of the superstructure for the lowest cost.In this paper, use genetic algorithm to optimize the cross section of prestressed concrete T-beam bridge. First, the basic theory of structural optimization, characteristics and optimization methods are introduced. And this paper analyzes and summarizes the genetic algorithm for the design of structural optimization. In particular, introduces the basic knowledge and the mathematical foundation of genetic algorithms and its work-steps. Second, this paper discuss some primary factor when genetic algorithm applied on optimal design, for example the mathematical modeling, constraint processing, design variables and the objective function and the controls parameter of genetic algorithm. Third, compared to the 20m,25m,30m,35m and other commonly used span prestressed concrete T beams design in the highway bridges standard drawing, using the GA toolbox in MATLAB7.0 to optimize the design. Using MIDAS CIVIL to establish T beam model for checking and analyzing the sections which have been optimized. Comparing the original design,Check the results of Flexural Performance of safety reserves and crack resistance of normal cross section, diagonal cracking performance before and after optimization. Finally, it is a conclusion that appropriate increasing in beam height and reducing the amount of prestressed reinforcement can reduce the project cost. The conclusion from the paper can be the reference for the construct designers in the real design projects.