Determinating The Flutter Derivatives Of Bridge Deck By Applying Numerical Simulation Method Based On ADINA

With the span of long-span bridges is becoming longer, the stiffness and damping ratio of structures decrease clearly and then critical flutter velocity falls accordingly. So flutter has been the most important problem in the design of long-span bridges. With the increase of computational speed in recent years, numerical experiments via Computational Fluid Dynamics are fast improved as an effective complement, although it still can't completely replace wind tunnel investigations. Major contents of the thesis include the following:(1) The forced oscillating procedure is used to determinate the flutter derivatives of the ideal flat plate with the discretization method of finite volume method(FVM) by using ADINA. The results are close to the Theodorsen's,theoretic solutions.(2) Flow field around the Great Belt East Bridge deck is simulated by using forced vibration procedure. The flutter derivatives are extracted from aerodynamic forces. The computed aerodynamic derivatives of the Great Belt East Bridge are compared with results from section model tests in wind tunnel and good agreement is found. Also, small deviation is shown on critical flutter velocity of Great Belt East Bridge based on flutter derivatives obtained from the present study and from wind tunnel tests. The availability of present approaches and its applicability to engineering are proved.(3) The aerodynamic devices used to improve bridge flutter stability under smooth flow are discussed by means of numerical methods. The flutter derivatives and critical flutter velocity of bridge girder cross-section with vertical stabilizer are compared with results of original bridge girder cross-section. It is shown that the vertical stabilizer is effective to increase the flutter stability.Comparing the present numerical approaches with wind tunnel tests, it is shown that the present study doesn't require expensive wind tunnels and also needn't prepare the scaled testing models, while casting off difficulties and higher operating costs. Therefore, a combination of numerical approaches with wind tunnel tests will make it possible to successfully evaluate the flutter stability of bridge girder cross-section.