Application Of CFD Method In The Aerodynamic Control Measures Research Of Long-span Bridge

With the development of modem materials, design theories and construction techniques, the wind effects on bridges become more and more prominent as the structures grow with longer span and more flexibility. Wind load has been one of the control loads in the design of modern bridge. After the collapse of Tacoma Bridge which was caused by wind-induced-vibration instability, much attention has been put on the research of improving the aerodynamic stablity of bridge by means of control measures. Considering the factors of economic, convenience and aesthetic, aerodymic control measure which was installed on the girder becomes the focal point in vibration control research.In this paper, we first talked about the domestic and forergn research status of wind-induced-vibration of long-span bridge, introduced several typical methods of wind-induced-vibration control of long-span bridge, generalized several effective aerodynamic control measures to main beam cross-section. Besides, we used two-dimension, 3-DOF method and wind tunnel experimental results to analyze two typical aerodynamic control measures--edge tuyere measure and central grooved measure, and we got the mechanics of buffeting control and the control action. The effectiveness of aerodynamic control measure to buffeting is proved.Then we mainly do research on wind resistance performance of long-span bridge by means of CFD method, introduce the research method of fluid mechanics and governing equation, and set forth the analytic species and use-process of FLOTRAN CFD in ANSYS software. The girder section model of Sutong Bridge was built, using N-S equation and standard k-εtwo equation turbulent model to proceed numerical simulation, we get coefficient of tri-component from different angles and compared the results with tunnel experimental results. The results showed, they agree well, which prove the effctiveness of CFD Method in this field.Combining front content, this article used CFD method and did further studies on the wind resistance performance of different girder sections after aerodynamic control measures adoped. Two aerodynamic control measures were mainly considered—edge tuyere measure and central grooved measure. Five different sections are designed considering the former which was based on the differences of tuyere; fifteen are considered in the latter based on the width of Channel. The tri-component force coefficient and pressure field, velocity filed distribution were given in the results by using CFD numerical simulation. Through the comparison analysis of various sections, we generalized the influences of aerodynamic control measures to the static wind load of long-span bridge. Finally, combining front content, we generalized the effects of two aerodynamic control measures, and gave the most suitable sections which were designed in this paper.