Wind Tunnel Test And Numerical Simulation Study On The Vortex-Induced Vibration Of Steel Bridge Tower With Variable Section

At present,researches on wind resistance of long-span bridges mainly focus on flutter and buffeting,and there are few theoretical researches on vortex-induced vibration.In the early stage of cable-supported bridges,the influence of vortex-induced resonance is often neglected due to the low tower height and most of the materials are concrete.With the rapid development of science and economy,the bridge span of bridge and the height of tower also increase accordingly.From the point of view of construction convenience,Lightweight,low damping steel is widely used in bridge towers.Although vortex-induced resonance will not cause direct damage to the steel bridge tower,it has the characteristics of low wind speed and high frequency,accelerating the local fatigue damage of the steel bridge tower,reducing the driving comfort and even endangering the driving safety,thus causing serious potential safety risks in construction and operation.Therefore,the vortex-induced vibration of steel bridge tower is of great significance for both theoretical research and engineering practice.This paper takes the bridge across the river in the west section of puyi road,JiangBei new district,Nanjing city,Jiang-Su province as the engineering background.The vortex-induced vibration response of a single-column steel bridge tower is studied by means of wind tunnel test and numerical simulation.Its specific work is as follows:(1)The vortex-induced vibration wind tunnel test of the aero-elastic model steel bridge tower was carried out under uniform flow field at 0°?15°?30°?60°?90° five wind angle.The time history of vortex-induced vibration displacement at 11.25m/s to 45m/s was monitored.Experiments show that the 0°(transverse bridge)and 90°wind direction Angle(along the bridge)have obvious vortex-induced resonance phenomenon.(2)The vortex-induced vibration of elastic steel bridge towers with variable cross-section is numerically simulated by CFD,and simulation method of vortex-induced vibration of elastic high-rise structures based on bi-directional fluid-solid coupling are explored.Combining ANSYS with MATLAB,the vibration mode function of the bridge tower is obtained.The UDF program is embedded in FLUENT to obtain the displacement of the elastic bridge tower based on second development of the CFD software.The SST k-?shear stress transport model and the dynamic grid strategy of rigid boundary layer region with dynamic grid region are used to simulate the flow field,and the numerical simulation of the vortex-induced resonance of the elastic bridge tower based on the bi-directional fluid-structure coupling is realized.The results show that the phenomenon of wind tunnel test is successfully reproduced by the method presented in this paper.The whole process of the elastic bridge tower from "beat" to "lock-in" to "beat" is captured with the increase of the reduced wind speed,and the vibration displacement of the bridge tower in the locked area is much larger than that in the non-locked area.The amplitude of numerical simulation in this paper agrees well with the results of wind tunnel tests.This method can be applied to the fluid-structure coupling analysis of similar structures and of great significance to structural safety assessment.