Research On Optimization Method Of Cable Force Of Cable-stayed Bridge

Since the 1960 s,the modern cable-stayed bridge system has experienced a lot of development,and now it has become one of the most advantageous types of kilometer bridge.The joint of cable and beam of cable-stayed bridge can be regarded as the elastic supporting point of beam.As a high-order statically indeterminate structure,cable-stayed bridge has higher requirements for line shape and cable force.Therefore,it is very important to determine the cable force of reasonable completion state of cable-stayed bridge.In this paper,the cable force optimization problem of cable-stayed bridge is studied based on the specified stress method.The main work and achievements are as follows:(1)the existing cable force optimization methods of various completed bridge States and construction stages are comprehensively described,and the cable force optimization method based on the specified stress method is introduced in detail.In this method,an additional degree of freedom,namely inelastic shrinkage,is added to the element,This degree of freedom can be used to simulate the prestress of cables,and the element stiffness matrix of truss element and beam element with inelastic shrinkage is given,as well as the form of overall stiffness matrix after assembly.(2)This paper introduces the application method of QT and the relationship of the internal modules,comprehensively considers the flow of the finite element calculation of this program,uses QT to write the visual window of human-computer interaction of the cable adjustment software,and introduces the layout of the main interface and sub windows,the realization process of the main functions,the response mechanism of the signal and slot function,and the realization of the slot function in this paper.(3)At the algorithm level,functions such as setting design variables and generating the influence matrix of design variables on optimization objectives are written.This paper introduces some C++ libraries and algorithm implementation process needed for algorithm compilation.The function is to set the design variables of cable adjustment according to the overall degree of freedom number of the structure,that is,the degree of freedom number of the inelastic shrinkage in this paper;set the target variable of cable adjustment according to the degree of freedom number,and then set it as the vertical displacement of the main beam.The concrete value of inelastic shrinkage is calculated by influence matrix.(4)Two examples are analyzed in this program: symmetrical single tower cablestayed bridge and asymmetric single tower cable-stayed bridge.The program and ABAQUS calculation results before the comparison and optimization of the main girder displacement are selected to verify that the static analysis results of this program are consistent with ABAQUS;the vertical displacement of the main beam is taken as the optimization objective to optimize the cable-stayed bridge,and a set of non elastic shrinkage values are obtained.The value of the non elastic shrinkage is obtained.The cable-stayed bridge is turned in ABAQUS The initial stress is added to the cable of cablestayed bridge.Through the calculation results of vertical displacement of main girder,the optimization results are analyzed to see whether the optimization results reach the optimization goal,and the optimization results show that the optimization goal is achieved and the cable force distribution is even.