Static Analysis And Cable Force Optimization Of Cable-stayed Bridge Based On Secondary Development Of ANSYS

With the improvement of manufacturing technology,the construction of long-span cable-stayed bridge in China has been developing rapidly.With the increasing span capacity,the nonlinear performance of the structure becomes more and more obvious.For the calculation and analysis of long-span cable-stayed bridge,the creep of concrete,the geometric nonlinearity of the whole structure and the optimization of cable force are unavoidable problems in the analysis.With the rapid development of modern cable-stayed bridge with dense cable system,it has become the most competitive bridge type with suspension bridge,which requires more research on mechanical properties.In this paper,the stress analysis and cable force optimization analysis of the cable-stayed bridge under the action of self weight are studied.The main contents of this paper are as follows:(1)In this paper,the finite element theory of geometric nonlinear analysis of long-span cable-stayed bridge is described,and the calculation steps of finite element derivation through Lagrangian formulation method and co rotation coordinate method are introduced.The advantages of co-rotation coordinate method in accurate calculation of element rigid body displacement and pure deformation are emphasized,and it is applied in the subsequent analysis.The influence factors of geometric nonlinear of cable-stayed bridge are described in detail And the methods used in various geometric nonlinear problems.(2)The three-dimensional ANSYS finite element model of Jingyue Yangtze River Highway Bridge with long-span cable-stayed bridge is established.The creep effect of cable-stayed bridge which only bears the self weight load is considered when the bridge is constructed in stages with a calculation age of 1000D.The creep effect of cable-stay ed bridge is summarized from the aspects of stress and deflection in each time course.The results show that with the increase of age,the maximum stress of the main girder and the main tower of the cable-stayed bridge is mainly distributed in the joint of steel and concrete and the cross beam under the main tower,the early speed is relatively large,then it is gentle,and the creep mainly develops within 500 days;the maximum fluctuation of the cable force can reach 2%only considering the creep.(3)In view of the problem of geometric nonlinearity in the completed state of long-span cable-stayed bridge,based on the structural calculation theory of co rotating coordinate method,the second development of the element is carried out by using the user programmable characteristics provided by ANSYS,and the plane model of cable-stayed bridge is established by using the user developed geometric nonlinear beam and bar element to carry out the geometric nonlinear analysis.The results show that:three geometric nonlinear factors are considered comprehensively The cable sag effect is the second,and the beam column effect and large deformation effect are the least.(4)The optimization of cable force in the calculation and analysis of long-span cable-stayed bridge can not be ignored.Based on the idea of the optimization method of cable force in the specified structural state,the iterative principle of cable force difference,which takes the design cable force as the optimization target,is adopted through ANSYS APDL is used for secondary development;the influence matrix method and genetic intelligence algorithm are used to search the optimal cable force,and the error between the final cable force and the target cable force is kept within 5%.