Investigation On Wind-induced Vibration Of Long-span Steel Trussed Arch Bridges

The long span seel tussed ach bridge is the wind-sensitive structural systems. Wind load is one of control loads for designing. Chongqing Chaotianmen Yangtze River Bridge is a typical case of this kind of arch. It is the object to be researched in this paper. By means of wind tunnel tests and numerical simulation, the wind-induced responses of the kind of bridge are studied, including the following aspects:①The data provided for the bridge buffeting were obtained in section model wind tunnel test. The wind-environment on the bridge site was simulated in wind tunnel tests before the process of aeroelastic-model wind tunnel test.②In order to meet the requirements of the force features and full aeroelastic model wind tunnel test for the kind of bridge, the method is proposed, which is that a single beam of variable cross-section simulates the truss arch of variable cross-section. Based on the method, the equivalent single-beam finite element model was established. Their dynamic behaviors of the models show that the equivalent finite element is consistent with the full-bridge model.③Based on single-beam finite element model, during the design of the whole aeroelastic model for the long span steel truss arch bridge, the variable cross-section"工"shaped core simulates the stiffness of the arch and the coat section is simplified in reasonable way. The method makes full-bridge aeroelastic model design feasible, the structure can be accurately simulated in the aspects of aerodynamic shape and the system stiffness. The results of dynamic characteristic test show that design of full-bridge aeroelastic model for the long span steel truss arch bridge is correct.④During the full-bridge aeroelastic model wind tunnel tests, the wind-induced response of the bridge were measured under the conditions such as the uniform flow and turbulence, all bridge stages, various wind yaw angles. The experiment data were analyzed by programming. Base on the data, wind-resistant behaviors of the bridge was analysed.⑤Based on the characteristics of the long-span steel truss bridge, the harmonic synthesis method are adopted to simulate three-dimensional wind field of the long-span steel truss bridge, and the time domain buffeting was analysed. The results were agreement with the experimental results. ⑥Considering fluid and solid coupling, the vibration equation method Runge-Kutta numerical method code were embedded in FLUENT software, and then the vortex-induced vibration (VIV) can be simulated. The two-dimensional fluid-structure interaction model was built and the VIV of the typical bar of the long span steel truss bridge aer calculated. The factors such as degree of freedom, damping ratio, wind angle, the former bar of disturbance are studied on the VIV.⑦Based on the platform of ANSYS WORKBENCH, the reasonable calculation of FSI for the bridge cable was carried out. At first, the FSI of the circular cross-section cable was analysis. The computational models were the established. The laminar flow model and the k-ωturbulence model were compared in calculations. The features of wind-induded vibration are analysed, such as the time-history of displacement and the cable surface pressure. Then, the FIS of two cable in parallel and serial were studied in wind vibration response.