Static Stability Anslysis Of Long-span Composite Beam Cable-Stayed Bridge

Along with the increase of span length, the use of the thin-walled box girder,the use of the high strength materials, the problem of stability becomes especially important. Because of its variant inner force under dead loading, nonlinear behavior in construction process and completed structure, the construction stability analysis and nonlinear analysis that consider those factors become very important.Composite beam is a new type girder,which is developed based on the foundation of steel structure and concrete structure. At present, it has been widely used in long-span bridges. Guanyinyan Yangtze River Bridge is a long-span cable-stayed bridge with composite girder as stiffening girder, which is on construction. This paper takes this bridge as background to get some conclusion on the whole stability. The main work has been completed as following:1. The finite element methods about the first and the second kind buckling problem of the cable-stayed bridge are expounded in this paper. At the same time, the essential difference of them and the two evaluation criterions about the stability of the cable-stayed bridge are discussed.2. The finite element modeling of cable-stayed bridge girder is discussed, and the stability analysis results under the several different work conditions of two different finite element models are compared, then the simulate of them are obtained3. The elastic and the double nonlinear buckling safety factors has been calculated under the several different work conditions,such as the longest of double cantilever, single cantilever stages,the dead loads stage and the stages of two load combinations. Then the buckling solutions are compared and the stabilities are evaluated. After this,considering all kinds of nonlinear factors,the buckling types and the most possible destroyed forms of the representative phases are also pointed.4. The influence of the cable-stayed bridge's whole stability was investigated through the structural parameter, load parameter, construction factors,the number of auxiliary piers and the average length of beam element.