| Hybrid girder cable-stayed bridge is a new structural system which combines the advantages of concrete girder and steel girder.In recent years,it has been widely used in bridge construction,because of its high stability,beautiful shape,strong crossing and other characteristics.The large span cable-stayed bridge is a high-order hyperstatic structure.The 1arge deformation of the structure and the joint action of bending moment and axial force make its geometrical nonlinearity become more significant.So it is very important to analyze the geometrical nonlinearity of the construction stage and the completed stage.However,the construction technology of the large span hybrid girder cable-stayed bridge is complex.Various factors that affect the goal of the bridge,leading to the bridge status of cable-stayed bridge may not conform to the design requirements.Therefore,to eliminate the influence of deviations,the parameter sensitivity analysis of cable-stayed bridge in the process of construction monitoring has great reference value.In this paper,the development trend,research status of geometric nonlinearity and parameter sensitivity analysis of cable-stayed bridges are analyzed.Based on engineering background of the construction monitoring of Guangzhou nansha port xijiang railway bridge,which is the largest cable-stayed bridge of the same type in the construction history of the double-track freight railway under construction.The geometric nonlinearity and parameter sensitivity of long-span hybrid girder railway cable-stayed bridge are studied by using Midas Civil.The main research contents are as follows:(1)The origin and development of cable-stayed bridge at home and abroad are analyzed.The research status of geometrical nonlinearity of cable-stayed bridge are systematically studied,as well as the research status of parameter sensitivity analysis of cable-stayed bridge.(2)Geometric nonlinear theoretical analysis methods of long-span cable-stayed bridge are studied and compared.Three main effects(sag effect of cable,large displacement effect and beam-column effect)that affect the geometric nonlinearity of cable-stayed bridge are introduced and analyzed.Three basic numerical methods for solving geometric nonlinearity equations are compared.(3)The basic structure and construction steps of Guangzhou nansha port xijiang railway bridge are introduced.The finite element model of the whole bridge is established with Midas Civil.The linear and nonlinear calculation of the bridge are carried out respectively.During the construction of the maximum cantilever and the completion stage of the bridge,the influence of geometric nonlinearity on the vertical displacement,internal force and stress of the main girder are analyzed and compared.(4)Under the condition of considering geometric nonlinearity and combining with the actual construction monitoring,sensitivity analyses are made for different construction parameters of Guangzhou nansha port xijiang railway bridge.A total of seven parameters,including the weight of main girder,cable stiffness,construction load,initial tension,temperature.The aim is to provide reference for the regulation and control of bridge construction monitoring process. |
