Stability Analysis Of Of Long-span Half-through Steel Box Arch Bridge And RSM Method Application Research

Steel box arch bridges are widely used due to their good environmental adaptability.As the span gradually increases,the stability problem becomes increasingly prominent.In the process of design and construction,finding the right combination of parameters and checking the stability are important steps to ensure the safety of steel box arch bridges.This paper uses this problem as the research background,relying on the Shuanglong Bridge under construction,using the finite element parameter method to optimize the stability of the construction stage,the stability of the completed bridge,the local stability at the weak position of the design,and the optimal layout of the stiffeners.In this study,the response surface method is applied to the process of parameter analysis,and combined with the Whale Optimization Algorithm,the obtained response surface model is optimized.The main research work and results are as follows:(1)Analyze the overall stability of the construction phase and the operation phase,obtain the stability safety factor and instability mode of the bridge at different stages,determine the construction node with the worst stability during the construction process and discovered the key parameters affecting the stability of the steel box arch bridge.(2)The change trend of the corresponding stability safety factor when the key parameters change is explored.The results show that within a certain range,the arch ribs are inclined inward,the number of cross braces is increased,and the cross braces are arranged in a "meter" shape,the boom is tilted and Increasing the rise-to-span ratio can increase the stability of the steel box arch bridge.When the critical value is exceeded,the effect will be significantly reduced.(3)The multi-scale finite element method is applied to the local stability calculation,and the local stability of the arch foot position,vault position,L/4 position and cable-beam anchoring position is studied,and it is verified that the local instability is not prior to the overall stability.As a result of instability,by adjusting the number of stiffeners at different positions,the influence of stiffener spacing on different positions of steel box arch ribs is analyzed,and suggestions are provided for the layout of steel box arch rib stiffeners.(4)Taking the above-mentioned key design parameters as design variables and taking the overall stability safety factor single objective function as the optimization objective,a stable safety factor response surface model was established,and the whale optimization algorithm was used to optimize the response surface.When the inclination angle is 2.64°,the number of transverse braces is 11,the arch rib stiffness is 1.43,the boom inclination angle is 63.52°,and the rise-span ratio is 1/4,the stability safety factor reaches its maximum value.Bringing the obtained results into the finite element software for calculation,the difference between the results is 2.91%,which verifies the feasibility of the combination of the finite element parameter method and the response surface method,and can provide ideas for subsequent bridge stability studies.