Numerical Approaches And Their Applications To Flutter Derivatives On Flat Box Girder

With the development of the computation speed in the past few years, numerical experiments via Computational Fluid Dynamics have been developed as a viable method. Although it can't replace the wind tunnel investigations, it turns out to be useful to study the various wind effects on long-span bridges.This paper studied the bridge effects with numerical approach, and the main contents of the policies can be summarized as follows:Firstly, the detached-forced vibration used to identify the flutter derivatives is introduced in detail. The Scanlan onset wind speeds for flutter method is taken for calculation .Secondly, the detached-forced vibration is used to compute the flutter derivatives of the ideal flat plate, and the results is closed to the Theodorsen's theoretic solutions.Thirdly, the decached-forced vibration is employed to compute flutter derivatives of a flat box girder bridge, and the numerical results are compatible with the data obtained from section model tests in wind tunnel. The comparison of onset speed for flutter between present study and full aeroelastic bridge model wind tunnel test is satisfactory.Forthly, the central stabilized plate is taken into account when culculating the flutter derivatives and onset wind speed for flutter. The result shows that the exist of the central stabilized plate has great influence on changing the fluid character, inducing the onset wind speed for flutter. In a word, it does good to the flutter stability of the bridge.Comparing with the wind tunnel tests ,the numerical approaches in this paper don't need expensive wind tunnels and costly equipments, and also free itself from measurement difficulties, higher operating costs and so on. The combination of numerical approaches and the wind tunnel tests will makes it possible to successfully evaluate the flutter stability of bridges girder cross-section.