Research On The Structural Model Modification Method Of Single Tower Cable-stayed Bridge

In recent years,with the application of computer simulation and computer intelligent technology in bridge engineering,structural finite element model updating technology has entered a new period of development.Structural finite element models are usually established on the basis of construction design drawings,but when building models,we often simplify or assume many uncertain factors or parameters,which often makes the theoretical analysis results of finite element models deviate from the actual structural response.Finite element model updating technology is to modify the initial design parameters of the structure,so that the modified finite element model can more accurately reflect the actual state of the bridge structure.In this thesis,the finite element model updating method based on response surface theory is used to modify the structural model of Changzheng Bridge in Jinzhai County.It is expected to provide decision-making and theoretical basis for the future management,operation and technical evaluation of the single tower cable-stayed bridge.Firstly,on the basis of summarizing the research status,the basic theory of finite element model updating technology is summarized and analyzed in detail.The related concepts of inverse mechanical problems are introduced,and the basic process of finite element model updating is analyzed.It is concluded that the process is essentially an optimization problem.The objective function is minimized by repeatedly adjusting structural parameters under specified constraints.At the same time,several key problems(correlation analysis,selection of correction parameters,establishment of objective function and optimization analysis)in the process of finite element model updating are analyzed and discussed in detail.Secondly,from the basic concept of response surface methodology,the selection of response surface function form and several common test design methods are introduced,and the advantages and disadvantages of various test design methods are analyzed.The selection of structural parameters to be modified and the method of optimum solution are briefly described.Taking a numerical simply supported beam as an example,the finite element model updating method based on response surface theory is successfully applied to the model updating,which verifies the feasibility of the method.Finally,taking the Changzheng Bridge in Jinzhai as an example,on the basis of load test analysis,the initial finite element model of the single tower cable-stayed bridge isestablished,and the relevant theoretical data are obtained by calculation.Through orthogonal experimental design,the response surface model which can replace the initial finite element model is constructed.At the same time,the objective function is established.Further,the response surface model is modified by the optimization algorithm,and more accurate structural parameters and finite element model are obtained.