Test Research On Vortex-induced Vibration Of A Long Span Cable-stayed Bridge

Because of the design theory and calculation method of progress, cable-stayed bridge has been very rapid development. However, As cable-stayed bridge span to the growing,bridge structure Becomes more and more gentle, more and more low natural frequency, and more sensitive to wind. aeroelastic problems often become design constraints of the structural strength, stiffness and stability. Therefore, the wind has become the key issues to decide whether the long-span bridges is successful or not.Vortex-induced vibration of the bridge is an important aeroelastic phenomena, it is easy for long-span bridges to occur Vortex-induced vibration.Although the vortex-induced vibration would not cause the structural failure, as the flutter or the buffeting,but it's very susceptible to occur at a low wind speed, moreover amplitude large enough to affect traffic safety, and cause stiffness damage, thus affecting the comfort of pedestrian and vehicle, and reducing fatigue life. Thus it is necessary to study vortex-induced vibration of bridge.This paper bases on a sea bridge, through the bridge section model wind tunnel tests of the main beam and full bridge aeroelastic model wind tunnel tests to study vortex-induced vibration of bridges, studying the vortex induced vibration response of it during construction state and full bridge state, and make comprehensive evaluation of vortex induced vibration of bridge structure, providing reliable wind parameters to the bridge design, and providing a reference for the future similar bridges design.The main contents as follows:In section model test,section model consists of four models: the recommended Scheme of girder, the first comparative scheme of girder, the second comparative scheme of girder. The scale of all of the Model is1:60, Length is 1.25m, width is 0.5m, length to width is about 2.5. Each model includes two configurations: railing and without railing. Through experiments, the critical wind speed of the vortex-induced vibration is received. And analyzed effect of the railing and the wind attack angle on the vortex-induced vibration. The test results showed that: the recommended Scheme of girder, the first comparative scheme of girder and the second comparative scheme of girder all occur vortex-induced vibration.In the full-bridge aeroelastic model tests, vortex-induced vibration of full-bridge states, the largest single-cantilever state and the largest double cantilevers state has been studied; The vortex-induced vibration properties of the single tower has been discussed; And analyzed the effect of the railing, the wind speed and wind direction on the vortex-induced vibration, and the reason for no obvious vortex-induced vibration. The test showed that: in each test state, the harmful vortex-induced vibration has not been found in the main beams and the bridge towers.