A numerical model for wind loads simulation on long-span bridges

A numerical model of the air flow problem around the girder of a long-span bridge is presented. The model is based on a finite volume formulation and it is able to simulate steady and non-steady wind loading conditions on the structure under the simplifying assumption, which is plausible for bridges with long spans, of a two-dimensional-like approaching flow. For a given bridge deck cross-section the proposed model allows the numerical evaluation of the flutter derivatives, which is useful to characterize in an analytical way the stability conditions of the overall wind-induced bridge response. In order to obtain satisfactory accuracy and stability of the numerical solution, a two-equation k-epsilon RNG turbulence model and special boundary conditions are employed. The accuracy and applicability of the model to wind engineering problems are successfully assessed by computing the aerodynamic behaviour of some simple cross-section shapes. Numerical results are also obtained for typical long-span bridge cross-sections and the comparison with the available wind tunnel measurements shows a good agreement.