Research On Cable Force Test And Control Of Long Span Cable-stayed Bridge

As the span of bridge construction continues to increase,the problems in design,construction and operation management are also increasing.Therefore,it is necessary to use relatively mature methods to solve new problems.The calculation and analysis of finite element for cable-stayed bridge is A very mature means at present.In this paper,through the cable test and control of actual engineering,the corresponding research work on the cable force test and control method in the construction process and the bridge load test process is carried out.According to the actual working principle and mechanical properties of the structure,corresponding solutions are proposed.The scheme establishes the spatial bar model of the whole process analysis of the construction,and compares the actual measurement data with the model theory.Then the reliability of the cable force test and control method is verified and applied in the actual engineering case.The content and related results are as follows:(1)Cable force test and control theory of cable-stayed bridge:based on linear analytical theory and basic dynamic equation of stay cable,according to the tension string theory of cable,the frequency method is considered to consider the influence of bending stiffness.The calculation formula of cable force and the calculation formula of cable cable force considering the influence of sag influence and elasticity are analyzed.The applicable range of two calculation formulas is analyzed.The construction control theory of cable-stayed bridge is described.In the calculation and analysis of bridges,some methods for determining the state of reasonable bridge formation and reasonable construction state are analyzed.The theoretical principles of each method and certain problems in the practical process are analyzed.Each method has its own advantages and disadvantages.How to control the construction process.Choosing a reasonable method makes the construction control process easier and more precise,which makes the final bridge state and the ideal target state better.(2)Finite element analysis of the whole process of cable-stayed bridge construction:Based on the theory of stress-free configuration control,two sets of nonlinear finite element software of Midas Civil and SAP2000 are used to analyze the whole process of construction of Beipanjiang Bridge,and two sets of models are adopted.The basic data between the two is unified by mutual check,and the analysis results are compared according to the same calculation parameters.The accurate construction control cable force and the stress and deformation state of other components are obtained.(3)Cable force control analysis of the whole process of cable-stayed bridge construction:during the construction process,the cable force control includes the anchor space coordinates and the unstressed cable length(the cable force).The whole process load is certain,and the structural stress is also determined.It is only necessary to control the geometric elements of the structural members,and the final force and deformation state can achieve the desired goals.There are many uncontrollable factors.It is very important to measure the cable force in real time by using the vibration frequency method.Comparing the measured cable force with the theoretical strength,the effect of the cable force test and control in the whole process of the construction of the Beipanjiang Bridge was verified.