Research On Modification Method Of Bridge Finite Element Model Based On Dynamic Response

What is the finite element method?It is a measure which is using mathematical measure to deal with structural problems in practical application.Because of its strong analytical ability,rapid calculation,high efficiency and practicality,it is widely used in bridges engineering fields.However,the finite element model also has some shortcomings,such as the difference between the finite element calculation model and the actual structure,the difference of material properties,the difference of boundary conditions and so on.which will cause the finite element model to be different from our real bridge structure.Far away,in practical applications,for the purpose of making the model more accurately restore the stress and strain of the bridge structure,the finite element model updating of the bridge becomes extremely important.Because the static test process of bridges is relatively complicated,the static correction is time-consuming and labor-intensive.In contrast,the dynamic correction of bridges is quicker and more efficient.Relatively speaking,the dynamic test can quickly obtain the test results,the results are relatively accurate,Easier to operate in practice.No matter at home or abroad,it has attracted much attention.In this thesis,based on the dynamic response method,the finite element model is revised,and the revision steps are as follows.At first,to identify the bridge frequency,the method used is the random subspace method.Then use the identified frequency as the correction target.Secondly,the finite element model is revised by the response surface method.Relying on the actual project,the research results of this thesis are verified,which fully reflects the reliability and accuracy of this research.The main conclusions are as follows:1.First,it briefly discusses the current scientific research on bridge finite element.And the research technical route is introduced.The stochastic subspace method and the finite element correction method based on response surface technology are introduced,because these two methods have better results for the identification of environmental excitation time history response.Through the analysis and judgment of the existing situation and the further exploration of bridge finite element correction,the research technical route of this thesis is put forward.2.Secondly,it introduces in detail the time-history response method based on the datadriven random subspace method（SSI-DATA）theory to environmental excitation,and uses MATLAB to write the modal parameter recognition program.Numerical examples are used to simulate the acceleration response data under environmental excitation and SSI-DATA is used to identify the mode of the structure.It is concluded that SSI-DATA can exactly distinguish the modal parameters of the structure,indicating that SSI-DATA can be used to identify the modal parameters of the bridge structure under environmental excitation3.Thirdly,it specifically introduces the correction method of the finite element model based on the response surface technology.By displaying the principle of the invisible function relationship between the design parameters and the response,on the basis of a limited number of calculations,the calculation efficiency is greatly improved while ensuring calculation accuracy4.Then,taking Liuhe Bridge as an example,use Midas/Civil to establish the initial finite element model of Liuhe Bridge,and conduct static and dynamic load tests on Liuhe Bridge to provide data support for the next correction.The finite element correction of Liuhe Bridge was carried out with response surface method and measured dynamic response data,and the corrected model was verified by static response data,and a benchmark finite element model that could be used for subsequent research was obtained,which laid a certain foundation for the actual bridge engineering5.Then,taking Liuhe Bridge as an example,the static and dynamic load test of Liuhe Bridge was carried out by using Midas/Civil finite element software to establish a model to provide data support for the next correction.The response surface method and the measured dynamic response data were used to modify the finite element of the Liuhe Bridge,and the static response data was used to verify the modified model.A finite element model that can be used for bearing capacity evaluation was obtained,which laid a certain foundation for the actual bridge engineering.Research and application basis6、Finally,the revised finite element model calculation results are used to judge the actual bearing capacity of the bridge project,the finite element structural parameter degradation is used to simulate the structural damage,and the equivalent calibration coefficient method is used to evaluate and predict the bearing capacity of the Liuhe Bridge.The superiority of the research in this article lies.