Wind Tunnel Test Research On Aerodynamic Characteristics Of Long Span Arch Bridge

With the development of material science,technology of construction and engineering design, the span of modern bridge has constantly increased.Bridge orient progress towards longer span, slender girder, small damp, flexible and light structure.Bridges are sensitive to the action of wind and their dynamic response are distinct. More attentions are paid on the vibrating problems of bend and torsion caused by the lift,pushing force and torsional moment which produced by wind. Today the theoretical calculation to wind resistance of long span bridge can not fit with design of engineering and the requirements of construction. Yet test chamber can reappear the actual actions of the bridge under the pressure of wind. So test chamber is one effective and convenient way to study wind induced vibration of long span bridges and it can supply lots of reference data to the engineering design service and to constructional enterprise. In addition, the test can improve directly the theory of wind resistance design to bridge and improve the code of wind resistance design.There are two important problems need to be solved. One is to simulate actually the actual structure, the other is to simulate the actual wind environment. With Chongqing Caiyuanba bridge as background, on the basis of wind tunnel test, this paper studies the vibration of bridge under wind pressure.First of all, this paper introduces the finite element method theory of the dead state structural dynamical characteristic. To simply the problom, this paper use space beam element to equal the parts of bridge.Secongdly,the aerodynamic model of the bridge is carried out obey the similarity theory. It compares the self-vibrate characteristic of the actual bridge and model bridge by numerical calculate .In addition, it has done field modal test.Finally,it has done wind tunnel test on the aerodynamic model. Spire,fence and roughness element are used for simulating the wind environment of the bridge located site.Response of the main bridge and main girder for wind action is tested in finished dead state and various construction stage at different wind direction.By recorganization and analysis the test data, the paper studies the stability of wind resistance at the finished dead bridge and the worst construction stage , it also studies the the vortex-vibration of main beam and main arch under the designed wind velocity .