Transient cross-wind aerodynamic loads on a generic vehicle due to bora gusts

Experiments were carried out to investigate transient aerodynamic loads experienced by vehicles on bridges using a generic prism model. A van model was exposed to an air flow, which simulated gusty bora winds blowing at the Croatian coast. The mean side force and the overturning moment of the vehicle increase nearly linearly with increases in the gust velocity. Two major mechanisms determine transient aerodynamic loads on a vehicle: vortex shedding from the bridge and the vehicle, and wind gusting. For the side force, the predominant unsteady flow mechanism is the buffeting by vortices shed from the bridge deck. The overturning moment is simultaneously influenced by vortex shedding and by wind gusting. With increasing wind gust strength, the unsteady component of the overturning moment becomes predominantly influenced by the wind gusting, while vortex shedding effects become less exhibited. The repetition rate of wind gusting does not seem to have a significant influence on transient aerodynamic loads.