Study On Parameters Sensitivity And Reliability Of Structural Of Long Span Cable Stayed Bridges During Construction Period Based On Response Surface Method

Due to its excellent mechanical performance,reasonable structural characteristics,beautiful shape and economic cost,the cable-stayed bridge has achieved rapid development in nearly half a century and has become the preferred bridge type in long-span bridges..And with the increasing span of cable-stayed bridges,the problem of structural stability and reliability during the construction period has attracted more and more attention.Based on the Kangbo Bridge on a highway in Sichuan Province,this paper analyzes the structural parameter sensitivity and structural reliability of the bridge during construction period.The specific work of this paper is as follows:1.The development of cable-stayed bridges at home and abroad is briefly introduced.The status quo of parameter sensitivity and structural reliability evaluation of long-span cable-stayed bridges at home and abroad are reviewed.The basic concepts of structural reliability analysis are briefly described.Reliability analysis method,and the theory of structural reliability analysis based on response surface method is introduced.2.A structural reliability analysis method based on response surface is proposed.The combination of MATLAB programming and general finite element software is used to fit the response surface function and calculate the structural reliability index.The analysis results show that the proposed algorithm can simulate the nonlinear response between random variables and structural response,and has good accuracy and computational efficiency.3.The response surface method is introduced into the sensitivity analysis of structural parameters,and the finite element model of the full bridge is established.The degree of influence of different structural design parameters(elastic modulus of cable,elastic modulus of girder,bending moment of inertia of bridge pylon,bulk density of girder,bulk density of bridge pylon)on the response of different structures(deflection of girder,internal force of girder,force of cable,deflection of bridge pylon,internal force of bridge pylon)are analyzed.It is concluded that the bulk density of girder is an important or main influence parameter for most structural responses.For the force of cable,the elastic modulus of cable is the main influence parameter.For the internal force of bridge pylon,the bulk density of bridge pylon is the main influence parameter.It is shown that it is feasible to introduce the response surface method into the parameter sensitivity analysis,and the more complicated finite element trial calculation is turned into a simple mathematical problem,and the important parameters obtained can be used as the basis for selecting random variables in structural reliability.4.The maximum cantilever stage of the bridge construction period is taken as the research object.Based on the programming of MATLAB and the finite element model of the maximum cantilever stage,the structural reliability analysis of the structural stability,cable stress and main beam stress based on RSM method is carried out.The reliability analysis model and performance function of the three are established respectively.Finally,the corresponding response surface display performance function is fitted and the reliability index is calculated,which can provide an effective basis for the control of key factors during the construction period.