Study On Dynamic Characteristic Of Long-Span Cable-Stayed Bridge

Modern bridges are developing in the direction of long-span and light weight. Cable-stayed bridges are designed to be long span because of its cross ability and self advantages, comparing with other bridge types.This thesis Taking preliminary design of the Second Jiujiang Changjiang River Bridge as background project. This thesis uses finite element software ANSYS, establishing a three-dimensional space finite element model, and analyzes its dynamic characteristics and response. The analyzed results reveals the vibration characteristics, force and deformation of the cable-stayed bridge structure under the moving loads. All these provide a theoretical understanding for design and construction. The main content and conclusions are as follows:(1) Through analyzing sensitivity of each parameter about cable-stayed bridge on the vibration characteristics, vibration mode as a whole is related to not just stiffness, but also to their own rigidity co-related components. At the same time, the boundary conditions on the cable-stayed bridge mode have a more significant impact on its own vibration frequency.(2) When loads are respectively moving through the bridge by speed of 60, 90, 120 km/h, the dynamic response of the bridge structure is obvious. The range of the dynamic magnification factor about the parameters is between 1.0059 and 2.4. The dynamic magnification factor is much larger than factor of 1.05 in the regulations of "Highway Bridge Design universal norms" , so the shock value factor of the problem should be taken seriously in the design of the cable-stayed bridge,.(3) When load going through a different traffic lane bridge, the effect of the deflection and the dynamic magnification factor of partial load is weaker than of moderate load; The effect of the vertical force of the main beams and the dynamic magnification factor of the moment whose the bottom of tower is greater than moderate load.