The Stability Research Of The Concrete-filled Steel Tube Arch Bridges

The concrete-filled steel tube arch bridges constitute a major component in the long-span bridge category because of its high carryring capacity, saving, low cost, aesthetics and better economic effect. However, arch bridges transmit the applied loads to axial force mainly, which makes arch bridge uniquely susceptible to buckling failure, especially with the slender arch ribs.First, this dissertation analyses the resreach present status and the theory of the stability of the concrete-filled steel tube arch bridges. Then based on the theory of stability , it introduces the capability and model of the mechanics, such as the ratio of width and span, the angel of toe-in of the arch rib, the variable cross-section,the arch axis coefficient and the ratio of height to span. These factors are discussed in order to analys the influence to the stability of arch. This dissertation suggests in projects reasonable parameters can be choosed to improve the stability of the bridge. Generally stablity problem is divided into two sorts, and many of the arch belong to the second problem, which is called imbalance at extremun and is the result of nonlinear. Safety factor will be overrated in linear theory, so nonlinear behavior in calculation is evaluated in this study. Finally, according to the real project, this dissertation evalutes nonlinear behavior in calculation ,and analyses the stability of different steps during the process and the whole stability of different state in finished stage. The result of the calculation indicates that the eigenvalue bucking analysis induce non-conservative result, due to the nonlinear influence, the result of nonlinear buckling analysis is far lower than the result of linear elastic analysis method.Base on the conclusion of study at home and abroad, directed against stability of long-span arch, this study, guided from numerical analysis, provides for theoretical direction to the people engaged in the near type arch bridge engineering after detailed analysis of the real project.