Random Seismic Response Analysis Of Low Pylon Cable Stayed Bridge

Railway low pylon cable stayed bridge is a new type of composite girder bridge.In recent years,this kind of bridge structure is more and more widely used in modern bridge construction because of its low pylon,rigid main beam and concentrated stay cables,which has the characteristics of rigidity of continuous beam and flexibility of cable-stayed bridge.Its stress is inclined to continuous beam bridge,the prestress in the main beam bears most of the load,and the stay cable can be regarded as external prestress,which plays an auxiliary role.At present,there are relatively few literatures on seismic research of railway low pylon cable-stayed bridge,especially on random vibration.Therefore,based on the actual project of Jinshajiang low pylon cable-stayed bridge,the following aspects are studied in this paper(1)This paper introduces the basic theory of bridge structure seismic research,including response spectrum method,time history method and random vibration method,and analyzes the advantages and disadvantages of several methods and the research process.The space bar model of Jinshajiang low pylon cable-stayed bridge is established by using finite element software,and the whole process of building the model is introduced in detail.(2)After considering the secondary dead load and local anchor block weight,and analyzing the sag effect of stay cable,the modal analysis of the finite element model of the bridge is carried out to determine the frequency and vibration mode of the finite element model of the bridge.The obtained structural frequency and vibration mode lay the foundation for response spectrum analysis,time history analysis and random vibration analysis.(3)The general steps of structural dynamic response spectrum method and time history method are introduced.The acceleration response spectrum is determined according to the location of the bridge site and the site type.The response spectrum of the model is analyzed along the bridge direction,transverse bridge direction,vertical bridge direction and three-way combination.The time history analysis is carried out to obtain the time history analysis results of the bridge direction,transverse bridge direction,vertical bridge direction and three-way combination The results of the two methods are compared.(4)The mathematical models of stationary random vibration power spectrum established by other scholars are summarized,and the advantages and disadvantages of each model are compared.Reference to the relevant parameters of the scholars,as the parameter input of the power spectrum model,provides the factual basis for the random seismic response analysis.Based on probability theory and random vibration theory,the statistical values of dynamic response of structures under one-dimensional,two-dimensional and three-dimensional uniform excitation are analyzed.At the end of this paper,on the basis of summarizing the research content of this paper,the problems that have not been considered in this paper are explained,hope to provide reasonable suggestions for follow-up research work.