The analysis of the dynamic behaviour of such bridges under wind excitation is usually performed on the basis of experimental tests on physical models in wind tunnels.

As an alternative to such procedure, some numerical methodologies have been developed, namely in terms of flutter analysis, though they are still based on some coefficients (flutter derivatives or Scanlan coefficients) whose evaluation still involves usually the use of experimental tests (forced vibration or free vibration tests).

An attempt to overcome such limitations consists in using different algorithms of Computational Fluid Dynamics (CFD), that permit the numerical simulation of the air flow around the deck cross-sections. This type of applications has been considered by several authors for the evaluation of force coefficients (drag, lift or moment) or Scanlan coefficients, but not for integral aeroelastic analyses of slender bridge decks, taking into account the temporal evolution of the dynamic flow- structure interaction.

After recent computer development, it has been developed and implemented a new numerical methodology for the aeroelastic analysis of slender structures [1,2,3]. This computational algorithm is a time incremental approach based on two numerical algorithms working together: one of them determines the fluid flow action and the other one evaluates the structural response. The Finite Element Method is used to model the structural dynamic behaviour, which can be idealised as geometrically non-linear. The numerical procedure used to calculate the fluid flow and its action on structures is based on the Finite Volume Method (FVM). It is consider a viscous incompressible unsteady turbulent bidimensional air flow solved on a structured control volume mesh.

The mentioned algorithm uses an iterative sub-process to achieve the correspondence between aeroelastic forces and structural movements at every time step.

In this context, this paper presents the application of that computer code developed on the basis of this new methodology to the aeroelastic study of a cable stayed bridge, with a -shaped deck cross section, and some of the most interesting results associated with the evaluation of the corresponding critical stability velocity are presented.

1

Lopes, A.V., "Aplicação da Dinâmica Computacional de Fluidos à Análise Aeroelástica de Estruturas Esbeltas", Ph. D. Thesis, Departamento de Eng. Civil, FCTUC, Coimbra, Portugal, 2001.

2

Lopes, A.V., Cunha, A., Simões, L.M.C., "Aeroelastic analysis of a slender bridge deck based on a Computational Fluid Dynamics algorithm", Proceedings of the 4th International Conference on Structural Dynamics - EURODYN2002, Munich, Germany, pp. 575-580, 2002.

3

Lopes, A.V., Cunha, A., Simões, L.M.C., "A Nonlinear Coupled Fluid-Structure Aeroelastic Analysis of a Slender Bridge Deck", International Journal for Numerical Methods in Fluids, 45, (Article in advance of print), 2004. doi:10.1002/fld.717

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