Analysis On Geometric Nonlinearity Of Double-Pylon Cable-Stayed Bridges With Single-Column And Investigate On Relative Deformations Of Separate Steel Box Girders

Cable-stayed bridges is a kind of flexible structure of high-order statically indeterminate which consists of main girder, pylon and cable-stayed. Under static loads,whether the structure of cable-stayed bridges will show significant characteristics of the geometric nonlinearity? During the cantilever construction of steel box girder in the cable-stayed bridges,whether the relative deformation will generate largely between girder under the action of deck cranes and hoisted girder? These are the research questions of this thesis.In this thesis, taking the Wuxiang Bridge of Nanning City as the project background, this bridge is a double-pylon cable-stayed bridges with single-column and separated steel box girders. It is unique in terms of its cable of double cable planes anchorage in the internal web of separated steel box girders, and the transverse spacing is only 6m.These existing features, embodies the study on the value of this cable-stayed bridges with the form of cable which approximate single cable plane.The main research contents of this paper are as follows:(1) In the cable-stayed bridges construction process, stiffness of the structure is small, and the geometric nonlinearity have impact on the structure. Based on the cable-stayed bridges in the study of geometric nonlinearity, elaborated on three geometric nonlinearity factors of cable-stayed bridges: the cable sag effects, effect of beam-column, the large displacement of structure effects, and describes the simulation methods of it in the finite element software.(2) Using Midas/Civil to establish linear finite element calculation model of the Wuxiang Bridge; And on the basis of this model were respectively established to finite element model which each consider cable sag effects, the large displacement effects and fully nonlinear effects. Study on the effect of various geometric nonlinear factors on each construction stage of cable-stayed bridges, and compared the change law of the influence of the geometric nonlinear effects, finally come to the conclusion that are beneficial to the future design and construction monitoring.(3) First of all, using large-scale general finite element software ANSYS 14.5 to establish the shell element model of separated steel box girders of Wuxiang Bridge. Secondly, anslysis of the relative deformation of steel box girder assembly port during the cantilever construction stage of the cable-stayed bridges, put forward suggestions that applicable to the manufacture and assembly on this type of steel box girder of cable-stayed bridges. Once more, comparison and analysis of the different forms of the longitudinal plate have impact on the relative deformation of steel box girder assembly port, put forward suggestions that applicable to the forms of the longitudinal plate on this type of steel box girder of cable-stayed bridges. Lastly, analysis the influence of longitudinal and transverse position of deck crane on the relative deformation of steel box girder assembly port, put forward suggestions that applicable to the position of deck crane on this type of cable-stayed bridges.