Research For Local Stability Of The Flat Steel Box Girder Of Cable-stayed Bridge

With the rapid development of large span bridge in China, the application of flat steel box girder is more and more extensive and its local stability issue is increasingly outstanding.This paper study the local stability of flat steel box girder on the basis of summarizing the research results made by domestic and foreign scholars, mainly done the following work:(1) the development process and present situation of cable stayed bridge is introduced; the construction and mechanical property is analyzed; the stability problem of bridge structure and local stability theory is summarized.(2) The critical bucking stress theoretical solution of quadrilateral simply supported slub is researched and then the energy and static methods are used to deduce the theoretical solution of critical bucking stress of stiffened plate.(3) The causes and types of nonlinear is presented, finite element model of the thin, opening and closed stiffened plate is established by using ANSYS analysis software, by analyzing geometric nonlinearity effect on the Bearing Capacity,the load and displacement curve is obtained.(4) finite element model of the thin, opening and closed rib stiffened plate is established by using ANSYS analysis software and They were buckling analyzed, the first order buckling coefficients, flexing stress and deformation form is obtained. The factor that impact on buckling stiffeners is analyzed which is the thickNess of plating,,the space and stiffness of the rib, The transverse diaphragm spacing, the regular pattern of the factor that impact on buckling stiffeners is obtained base on the analysis result.(5)by analyzing the flat steel box girder of the background of project with the help of the finite element model software, We known the first occurrence of buckling in diaphragms during the entire beam segment buckling analysis.(6) the impact of the stiffness on the rib stiffeners is summarized, The concept of reasonable stiffness ratio is proposed, the regular pattern of Required Stiffness ratio when both the rid and motherboard of the stiffeners generates Local buckling at the same time is analyzed.