On the wind loading mechanism of long-span bridge deck box sections

Box girders have been used in the last thirty-five years to stiffen suspension and cable-stayed bridge decks, as an alternative to truss and plate girders. Their good performance, both from the structural and from the aerodynamic points of view has been widely recognised. More recently, an improved version of the box girder, the multi-box girder has been developed, which is presently considered the state-of-the-art in terms of bridge deck aerodynamics. Nevertheless, the older truss and plate girders are well still in use, and are often preferred to box girders, especially in North America and in eastern Asia. The aerodynamic behaviour of bridge deck box sections is examined in this paper. The mechanism of the wind excitation is investigated through the analysis of the mean and fluctuating deck pressure distributions, and their relation to the characteristics of the deck motion. The possibility of implementing passive or active aerodynamic control techniques to improve the deck stability is also touched in the paper.