Static Stability Analysis Of Long-span Hybrid Girde Cable-Stayed Bridge

Hybrid girder cable-stayed bridge is widely applied in the construction of large span bridges for its reasonable mechanical properties and economy superiority. But together with the increase of span length and the use of high strength materials, the box girder is thinner and the tower is higher. Coupling with its variant inner force and obviously nonlinear behavior, the stability of cable-stayed bridges during construction and serving stage becomes much more important.This paper includes two major parts:the first part is the theoretical basis. This part mainly introduces the development of cable-stayed bridge, the nonlinear and stability analysis theory of the cable-stayed bridge. The second part is modeling and analysis section. This part takes the Edong Yangtze River Bridge with a main span of 926m, which is a hybrid girder cable-stayed bridge, as the engineering background. The elastic, geometry nonlinear and double nonlinear safety factors of stability is calculated under several different loading conditions, such as the longest single cantilever stages, aftercrop permanent load stage and the stages of seven load combinations. Then the solutions are compared and the stabilities are evaluated. Besides, considering all kinds of nonlinear factors, the buckling types and the most possible destroyed forms of the representative phase are also pointed out. Furthermore, a formula for approximate elastic buckling load of the cable-stayed bridge is deduced by using the energy method, and the influence of the cable-stayed bridge's global elastic stability by some factors such as the stiffness of the tower and the girder, the number of auxiliary piers as well as the dismantling of scaffold is investigated.