Elastic-Plastic Stability Analysis Of Long Span Steel Box Girder Cable-Stayed Bridge

With the development of bridge engineering, the span of bridge is refreshed constantly. In the field of long span bridges, cable-stayed bridge is appreciated by large crossing capability and beautiful appearance. With the development of span, the stability questions of cable-stayed bridge are more and more obviously. In order to analyze elastic-plastic stability of cable-stayed bridge, the calculation program for long span cable-stayed bridge with steel box girder is established. The elastic-plastic stability is computed accurately by building plane frame model based on the calculation program. Details are as follows:Firstly, the research direction is proposed and methods are determined by studying the development of cable-stayed bridge and research status of stability questions. During the stability analysis process according to the cable-stayed bridge, which is flexible architecture, the effects of geometric nonlinearity and material nonlinearity are included, and the including methods are explored.Secondly, studies for geometric characteristics calculation and triangulation meshing algorithm which mainly discussed background mapping method and scanning line method were conducted. Based on theoretical research, the calculation program for elastic-plastic geometric characteristics is established and then nesting it in the cable-stayed bridge stability computational procedure to ensure that the section parameters can be updated in real-time during the plastic development process, so the elastic-plastic effect of material is included in stability analysis process.Thirdly, according to the two kinds of stability theory, using the finite element method, based on the Visual Studio2010application development platform, the elastic-plastic stability analysis program of cable-stayed bridge is established, and through the member model, the elastic-plastic stability and the first stability eigenvalue for the structure are calculated. At the same time, the program calculation results are verified by specific examples.Finally, using the calculation program and making cable-stayed bridge, which has a main span of780m, with steel box girder as the engineering background, the stability analysis for cantilever construction stage and service stage are carried out by building plane finite element models. At the same time, elastic-plastic instability failure mechanism and reasonable value of stability safety factor for cable-stayed bridge are studied.