Research On Wind Resistance Of Luzhou Hedong Yangtze River Bridge Based On CFD

With the rapid development of the times and the social economy,human demand for large-span bridges is also increasing.The increasing span of cable-stayed bridges also causes an increase in their wind sensitivity.Therefore,it is essential to study the wind resistance of large-span bridges.This article takes the construction project of Hedong Yangtze River Bridge in Naxi District and Jiangyang District of Luzhou City,Sichuan Province as an example to study the wind resistance performance of Hedong Yangtze River Bridge.The main contents are as follows:(1)Assuming that there is a virtual standard weather station in the bridge site area,the inverse distance wind speed weighted interpolation method is used to process the wind speed data of the weather stations around the bridge position,so as to determine the design reference wind speed of the bridge position,and carry out a three-dimensional pulsating wind field numerical simulation.The MIDAS and ANSYS softwares were used to build the finite element model of Hedong Yangtze River Bridge,which was checked and compared with each other to verify the correctness of each mode.(2)The basic theory of computational fluid dynamics is reviewed,and the current research status of CFD numerical simulation in the field of bridge wind engineering and the characteristics and use methods of two-dimensional CFD simulation platform are introduced.Using Xiao Niu CFD software to calculate the optimal meshing situation and Reynolds number,and then calculate the three-component force coefficient of the cross section of the main beam at an angle of attack of-10°～10°.The curve of the threecomponent force coefficient of the main beam section as a function of the angle of attack is fitted to prepare for static wind and buffeting response analysis.(3)In view of the fact that the vertical bending and torsional amplitudes of the vortex vibration in the wind tunnel test of the Hedong Yangtze River Bridge do not meet the requirements of the code.In this paper,the CFD numerical analysis method is used to simulate the vortex vibration control effect of the four aerodynamic measures such as the air nozzle,the lower central stabilizing plate,the inverted L-shaped deflector and the lower horizontal deflector,and the detailed analysis of the vortex response law when the size of various measures parameters changes.The research shows that No.1 and No.5should be used for the air nozzle.The lower central stabilizing plate is recommended to use the stabilizing plate with m> 2H height.The inverted L-shaped deflector can use the L-shaped plate with a=2/3H and b=1/2H The lower horizontal deflector is not suitable for improving the cross-sectional vortex vibration performance.The inverted L-shaped deflector is the relatively best aerodynamic selection.(4)Based on ANSYS APDL language,a three-dimensional nonlinear static wind stability analysis program for the bridge was compiled,and a three-dimensional nonlinear static wind stability analysis of the Hedong Yangtze River Bridge was carried out.The calculation results show that the critical destabilizing wind speed of the bridge is 120m/s,the displacement value of the main beam is obviously unevenly distributed along the lengthening direction,and the other positions are smaller than the mid-span position.The static wind deformation is the result of the complete coupling of the main beam vertical bending,transverse bending and torsional deformation,the final instability form is the spatial bending-torsion coupling of the main beam.(5)Based on Scanlan buffeting theory,ANSYS APDL language was used to compile a bridge buffeting response analysis program.For the Hedong Yangtze River Bridge,the buffeting response of different values of aerodynamic admittance was analyzed,and the buffeting response analysis of the bridge at the completed state and the maximum construction cantilever state both at the reference wind speed were carried out.The research shows that the buffeting response when the aerodynamic admittance is 1 is relatively safe.The influence of Sears function on the buffeting displacement response of the main beam is lateral displacement> torsional displacement> vertical displacement;The maximum lateral and vertical displacements of the mid-span bridge are 0.07 m and0.77 m,and the maximum lateral and vertical displacements of the cantilever state are0.096 m and 1.415 m,respectively.