The Analysis On Sling Responses Of Suspension Bridge With Long Span Due To Vortex-induced Vibration

In the bridge engineering,the bridge tower,the main cable,the sling,the stiffening girder and the pier and other components are prone to vortex-induced vibration.This periodic vibration is easy to cause fatigue damage to the component,affecting the use and life of the component,especially in the bridge structure with the force transmission components.In the suspension bridge system,the sling is the main force transmission component between the main cable and the stiffening girder,the vortex-induced vibration of the sling not only causes fatigue damage to the structure,but also affects the normal use of the bridge and the driving comfort of the vehicle.Using numerical simulation method,the vortex-induced vibration of single and double cylinders was studied and the influence of surface roughness on the vortex-induced vibration response of tandem suspension rods was analyzed.The main research contents and research results are as follows:?1?Using numerical simulation,the Rigid Body module in software CFX was used to simulate the fluid-structure interaction.Through the verification of the model,find that this method can accurately simulate the fluid-solid coupling.With reference to existing research,the correctness of LES turbulence model is verified.?2?Based on the engineering background of Runyang Yangtze River Bridge's Nanxun Suspension Bridge,in order to compare the difference between double cylinder and single cylinder,the vortex-induced vibration of a single cylinder is calculated.The results show:There are two peaks in the transverse vibration amplitudes of parallel twin cylinders,and the two vibration amplitudes of the two cylinders are not much different,and the maximum values of vibration amplitudes of flow direction are quite different.In the tandem cylinder,the vibration amplitudes of the two cylinders in the two directions are quite different.The transverse vibration amplitude of a single cylinder is larger than the transverse vibration amplitude of the parallel double cylinder and the upstream cylinder in the tandem double cylinder but smaller than the lateral amplitude of the downstream cylinder,comparisons have shown that there is an interaction between a twin cylinder and a tandem cylinder.At the same time,the influence of the anti-vibration frame on the vortex-induced vibration of the tandem cylinder is also considered,compared with the previous calculation results,the lateral amplitude of the upstream cylinder slightly decreases and the maximum amplitude of the downstream cylinder has not changed,but only appears at a large reduced speed.The upstream cylinder vibrates at a reduced amplitude,but decreases less than the downstream cylinder.?3?The influence of roughness on vortex-induced vibration of tandem double cylinder is analyzed.The results show:The upstream cylinder is more sensitive to changes in the roughness than the downstream cylinder.The lateral amplitude of the upstream cylinder decreases with the increase of roughness,and the flow amplitude increases with the increase of roughness.The downstream cylinder has a critical reduction rate of U_r,crit.When U_r>U_r.crit,the lateral vibration amplitude of the downstream cylinder will decrease with the increase of roughness,and the flow amplitude increases with the increase of roughness slowing shrieking.