Numerical Research On Aerodynamic Control Measures Of The Long-span Bridge

With the progress of modern materials, bridge design and construction levels, bridge structure toward the developments of larger span, more flexible, and more susceptive to the wind action which becomes an important governing factor to bridge design. Wind-induced vibration of large span bridges has become the vital problem in the fields of bridge engineering and wind engineering. Great concern has been put on the research of improving the aerodynamic stability of bridge by means of control measures. Considering the factors of economic, aesthetic and convenience, aerodynamic control measure which was taken on the main girder becomes the key in vibration control research. To date, wind tunnel test is still the most fundamental way to evaluate the aerodynamic stability which requires long test period, high cost, and complex and expensive test equipments. Meanwhile, the flow visualization in the wind tunnel is very difficult and brings obstacles to reveal the interaction mechanism of bridge and flow. So, the development of computer technology and computational fluid dynamics provide a possible effective mean to study the wind-resistance of bridge instead of wind tunnel test.This paper researches and discusses the wind-resistance of large-span bridges by numerical methods, and the main contents can be summarized as follows:1. The present research status at home and abroad of the wind-induced vibration of large span bridges, the use of the software FLUNET, the detached-forced vibration method used to identify the aerodynamic force and flutter derivatives of bridge section, and the Scanlan identification method used to calculate the flutter critical wind speed are all introduced in this paper.2. Based on the numerical calculations theory and simulation methods, the effects on the wind-resistance of bridges through setting different width stable plates on the both sides of the bridge section are discussed, with the use of flow field analysis, flutter derivative comparison, and the flutter critical wind speed calculation method, and under the angles of attack of-3°,0°, and +3°respectively. Meanwhile, the value of flutter critical wind speed obtained by the numerical algorithm and the aeroelastic full bridge model wind tunnel test are compared and discussed.3. Under the angle of attack of 0°, the effects on the wind-resistance of bridges through setting different height central stabilizers are also studied. The analysis results show that the existence of the different height central stabilizers has great influence on changing the flow fluid characteristics around the beam body and improving the flutter critical wind speed.4. Under the angle of attack of 0°, different aerodynamic control measures, including only setting baffle or central stabilizer, and simultaneous setting baffle and central stabilizer, are taken on certain main girder section. By comparison, the correct aerodynamic control measure is adopted.