The Stability Analysis Of The Long-Span Cable-Stayed Concrete Filled Steel-Tubular Arch Bridge

The long-span cable-stayed concrete filled steel-tubular arch bridge is a kind of new bridge structure form, which combines the cable-stayed bridge and the arch bridge harmoniously. It not only exhibits the respective merits of the cable-stayed bridge and the arch bridge, but also makes two kinds of advantages of bridge type get to add mutually. The cables fasten on the arch rib can make the bridge more beautiful, at the same time, these cables can share in the load of the arch rib, raising the arch rib of whole inflexibility, strengthened the stability of the whole bridge. However, for the long-span bridge, including the long-span cable-stayed arch bridge, the stability problem is always ineluctable, especially, the out-of-plane stiffness of the arch rib is far smaller than the in-plane stiffness of the arch rib, so, the out-of-plane stable problem is the problem that have to be considered.This text discusses the stability of the cable-stayed arch from the theories firstly, it is divided into the in-plane and the out-of-plane to contrast the cable-stayed arch with arch structure of the stable critical load, Tallying up the influence of the cables on the stability. Then, with cable-stayed arch bridge which is the fourth big bridge be under construction in XIANGTAN city Hunan province for engineering background, makes use of large and in general use finite element software ANSYS to analysis the stability of the bridge. Firstly, the linear method is used in analyzing the finite element model of the bridge, mainly computes the stability coefficient and instability mode of the bridge, considering the constant load, the wind load and the various disadvantage load. Secondly, the nonlinear stability is computed, considering the constant load to contrast the stability coefficient of the linear method with the nonlinear stability coefficient of results taking into account the geometrical nonlinearity and the double nonlinearity. At last, on the basis of the linear finite element model, the effect of different factors such as the stiffness of the arch rib, the arrangement form and the arrangement position of the lateral brace, the sloping angle of arch ribs, ratio of the width to the span, the form of the hangers, the stiffness of bridge decks, cables etc is discussed. these influence of the factor upon the whole bridge stability are studied.