Study On The Stability Of Long-Span Steel Arch Bridge

As a prime style of bridge,the arch bridge has been for over three thousant years old up to now. With the increase of the span of the arch bridge,the stability problem becomes more and more evidence and it is one of the most important control factors of arch bridge design.This paper bases on the Xinguang bridge in Guang zhou.By analysing its stability problem,I discuss all kinds of factors affecting the stability of long- span steel arch bridge,in order to provide profitable suggestion for design of the same kind of bridge.Generally stability problem is divided into two sorts.The first one can come down to evaluate eigenvalue problem finally, which is very easy to be calculated. Due to the effect of the material nonlinear, geometry nonlinear and original bug , the second one is the problem about ultimate load carrying capacity which is more reasonable comparing to the true result.According to the existed theory at present, starting from both the eigenvalue stability and ultimate load carrying capacity, and by using the United element method, I analyse the factors influencing stability and carrying capacity of ultimate load of long span steel arch bridge ,such as braceing style and layout, intensity of deck, arch ribs obliquity, transverse wind loads and so on.Seen from the result of the calculation,it indicates that due to the influence of material nonlinear the safe stability coefficient draws from nonlinear stability analysis method is far lower than the one does from eigenvalue buckling analysis method, so eigenvalue buckling analysis may induce non- conservative result,and the "—"style bracing is adapt to setup on the top of arch while the "K"style bracing is adapt to setup on the 1/4 span and near of the top of arch;Due to the influence of non-keep- direction force, the lateral rigidity of deck is increased,and the lateral stability of arch bridge will be enhanced;With the increase of arch rib's obliquity,the linear stability coefficient will be increased accompanied with the carrying capacity for ultimate loads being decreased,it is important to select a reasonable obliquity angle by comparing of all kinds of factors; because transverse wind load will greatly reduce the ultimate load carrying capacity, it is necessary to verify the stability of anti-wind during bridge design.