Vortex-induced Vibration Wind Tunel Test Of 5:1 Rectangular Sectional Model With Large Aspect Ratio

Vortex-induced vibration is a typical kind of wind-induced vibration which is easy to occur in long-span bridges under low wind speed.Although it does not constitute a security potential,it affects the life and comfort of the bridge,and brings great social impact.Sectiontal model tunnel test is a commonly used method to study the vortex-induced vibration performance of bridges.In this paper,the nonlinear characteristics of the elastic suspension system,the influence of vortex-induced vibration amplitude and the prediction method are studied by the wind tunnel test of the elastic suspension model with large aspect ratio of 5 : 1rectangular section.The main research contents are as follows :(1)on the the locking interval and amplitude of vortex-induced vibration with 5:1rectangular cylinder by taking wind tunnel tests of Sectional model vortex-induced vibration under different wind attack angles and different Scruton numbers.Analyzed the effects of wind attack angles and damping ratios on the critical flutter wind speed and flutter form of rectangular section by taking the sectional model flutter tests under different wind attack angles and damping ratios.(2)Through the free vibration test of the spring-suspended systems,the nonlinear characteristics of the frequency and damping of two elastic suspension systems with additional eddy current damping and additional damping film damping are identified,and the nonlinear effects of eddy current damping and damping film damping on the damping and frequency of the system are analyzed(3)The variation curve of vortex vibration amplitude with wind speed measured by wind tunnel test was used to identify the parameters of the structure-wake oscillator coupling model of 5 : 1 rectangular section by using the least square method.The vortex-induced vibration characteristics of 5 : 1 rectangular section with different Scruton numbers were predicted by using the identified structure-wake oscillator coupling vortex-induced vibration model.The reliability of the prediction of wake oscillator model was verified by comparing with the results of wind tunnel test.(4)A structure-tail flow oscillator-TMD coupling model is established.Taking the minimum amplitude of vortex vibration as the optimal objective,the TMD parameters are optimized.The optimal frequency ratio and optimal damping ratio of TMD under different mass ratios are obtained.The influence of TMD dynamic parameters on TMD control effect and the influence of tail flow oscillator model parameters on TMD control effect are analyzed...