Structural Characteristic Study On Beam-Arch Combined Bridge

Beam-arch composite bridge is an externally static, internally super-static structu-re. It is one of the most frequently used beam-arch combination systems without thrust, which organically combines the two systems of simple-supported beam bridge and the arch bridge. Arch rib structure is generally made of concrete-filled steel tube, with wind bracing set on the bridge. In addition to the arch ribs, the stiffening tie beam is also one of the main bearing components. The plane framework has two parts, the stiffening tie beam and the lateral beam, connected with each other for joint force. Take Ma Zhangba bridge of Suijiang, Yunnan as an example, this article analyzed the characteristics of stress on the combined structure of this bridge which could be referential for the design and analysis of this kind of system bridges.Firstly, the finite element theory is used to establish the plane frame model in analyzing the forces during the process of building. Then, the main variable parameters are changed from the perspective of designing, in order to compare its influences on the internal force and displacement of bridge. Lastly, after the construction of the space finite element model of the whole bridge and the comprehensive analysis of the elastic stability and seismic resistance, we can come to the following three conclusions:1、The ratio of the rise to span and the stiffness ratio are influential to the internal forces and the displacement. So selecting an optimal range of these parameters is very important for designers.2、During the operational phase, the effect of non directional force of suspender plays a key role in controlling the well running of the lateral stability of the bridge.3、In dynamic character analysis, the outer-plane stiffness is weaker than the inner-plane stiffness for this kind of bridge, so the lateral vibration is more outstanding, and the inner-plane vibration appears later. Using the response spectrum method for the seismic analysis of displacement response can also come to the same conclusion.Because of the complexity of the stress situation of this kind of bridge, the research in this field is still a long way to go. Future analysis can lay the direction on the shrinking and creeping of concrete, local stress analysis of arch-beam fixed joint, the nonlinear stability should take advanced research and so on.