Research On Nonlinear Algorithm Of Bridge Line And Cable Force Of Cable-Stayed Bridge

At present,the construction of cable-stayed bridges in China is at the international advanced level.Due to its unique flexible structural system,the cable-stayed bridge has been continuously reduced with the increase of construction sections during the construction process,and the geometric nonlinear problem has become more and more significant.Therefore,the calculation model is established strictly according to the whole process of construction period,and the internal force and line shape of the bridge can be effectively controlled to meet the requirements.This paper depended on the Fengdu Yangtze River Second Bridge,and the geometric nonlinear iterative analysis is carried out for the unclosed problem of the inverted-positive assembly calculation.Keeping the shear force for zero is used to ensure the internal force state of the bridge.In this internal force state and the bridge-line target,the forward-backward calculation is carried out,and the construction process is considered to be a nature updated Lagrange correction system.The updated Lagrange formulation is used to calculate the whole process of geometric nonlinear construction,and the overlapping curve of the inverted and the formal dressing is established considering the creep factor.At the same time,under the same structural system,in the elastic range,the transition of any two stress states do not depend on the path,which means the result of the one construction stage and the multi-construction stage demolition in the demolition process are same.The main work of this paper is as follows:(1)Investigate the results of the development of the cable-stayed bridge,the calculation analysis theory and the bridge state calculation method.The results show that the influence of geometric nonlinearity on the internal force and shape of the bridge during construction needs further research.(2)The application of the stress-free state control method in the construction control of the cable-stayed bridge and the calculation of the internal force of the bridge is summarized.And reviewed the formula of the linear derivation of the catenary.The theory of static geometric nonlinear analysis of cable-stayed bridges,geometric nonlinear influencing factors and finite element analysis and calculation methods are introduced.By analyzing the geometric nonlinear causes of the incomplete,it is proposed that the geometric nonlinear iterative calculation using the UL formula is more in line with the construction process.(3)The shear force zero method is used to determine the internal force state of the structure,and the forward-backward overlapping calculation for each construction stage is performed under the target bridge line shape;In the case of small deformation,the results are obtained while the large deformation,the geometric nonlinear iterative calculation is performed,and the nonlinear forward-backward overlapping result is obtained.and finally give the overlapping curve.Then comparing the first stage of stepby-step demolition,the result of the second stage of demolition and the result of two stages of simultaneous demolition.The results show that the transition from one stress state to another is independent of the process when the structural system is unchanged.Therefor,the demolition process can be divided as needed.(4)Using the parameters of Fengdu Yangtze River Bridge to carry out modeling analysis,carry out closed analysis and calculation,and compare the influence of various nonlinear factors.Using the results of the reverse-precision geometrical nonlinear closure of the pre-construction stage,the same results as the case are obtained.The calculation of the influence of various geometric nonlinear factors on the internal forces of the construction control is carried out,and the beam-column effect had least influence,large distortion and the cable sag effect.