Numerical Simulation For Aerodynamic Characteristics Of Bridge Structure

Based on numerical simulation and bridge belt suppose, the planer model of bridge section is established by computational fluid dynamic method. The aerodynamic characteristics of long span bridge section along with the change of Renold number under the wind action, the effect of bridge guard railing to aerodynamic characteristics of bridge structure, the influence of vehicle-bridge coupled wind pressure effect on the aerodynamic characteristics and wind pressure distribution of bridge single and vehicle single, are respectively studied.The mean aerodynamic force coefficient of the streamline-liked and the∏-type bridge deck model are studied, along with the change of Renold number. Meanwhile, the aerodynamic force coefficient of streamline-liked bridge deck is calculated with different ratios of width to height and the results are compared. With the ratio of width to height changed step by step, the aerodynamic characteristic of streamline-liked bridge deck is accordingly changed step by step, which shows good comparability and streamline characteristic.The drag coefficient, lift coefficient and moment coefficient of two bridge section models under construction (with no bridge guard railing) and completion (with bridge guard railing) stages, are respectively calculated and compared with different wind directions action. The result shows that the airflow of bridge section is changed with bridge guard railing. Accordingly, the change speed of external pressure of section becomes slowly, and the lift and moment of structure decreases, which could improve the aerodynamic characteristic of bridge structure and increase the safety of traveling on the bridge.Aerodynamic characteristic and wind pressure distribution of vehicle-bridge coupled system is studied. Renold stress turbulence model is chosen and three computational models, that are single bridge, single vehicle and vehicle-bridge coupled system, are established respectively. In different wind directions, aerodynamic force coefficients of the three models are calculated and wind pressure distributions of different models are compared. Compared with the single vehicle and the single bridge model, the coupled effect is considered in vehicle-bridge coupled system. It is shown that aerodynamic force coefficients of vehicle-bridge coupled system, consisting of lift coefficient, drag coefficient and moment coefficient, significantly change in different wind directions. The results indicate that aerodynamic characteristics of vehicle-bridge coupled system are greatly influenced by the coupled effect between the vehicle and the bridge, which should be taken into account to insure traveling safety during bridge design.