Research on Design and Optimization of Steel Plate Composite Girder Bridge Based on Accelerated Genetic Algorithm
This study presents a cross-section optimization method for the highway simply-supported steel plate composite girder bridge,based on the accelerated genetic algorithm,to address the steel consumption optimization issue.By using the steel amount of main girder as the objective function,the cross-section parameters of the main girder as design variables,and the load bearing capacity and deformation of the composite girder as constraints,the optimal cross-sectional dimension is calculated.The south approach of Wuxue Changjiang River Bridge is used as a case.Based on the internal forces of the bridge calculated when the steel main girders are arranged at different spacings,the accelerated genetic algorithm is applied to obtain the optimal cross-section of the steel main girder,and in turn,figure out the minimum steel consumption per linear meter,as well as the overall steel consumption of the full bridge along with the variation of girder depth.Based on the optimization,a minimum steel consumption design scheme was proposed,and finite element modeling was conducted to verify the mechanical property of the structure after optimization.It is shown that the cross-section optimization method based on accelerated genetic algorithm for the composite girder bridge displays sound convergence and extremum optimization capability.As the spacing of steel main girders gets bigger,the dimension of the steel main girder and steel consumption also rise,but the steel consumption of the overall bridge drops.There exists an optimal girder depth that is related to the most economical steel consumption,and the girder depth increases as the spacing between the steel main girders becomes bigger.The deflection and stresses calculated by the proposed minimum steel consumption design scheme are smaller than the limit values suggested in the codes,indicating that the steel main girders have sufficient safety margin and meet well the load bearing requirements of the structure.
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