Aerodynamic Tailoring of a Bluff Deck Section Subjected to Inclined Winds Due to the Complex Orography of the Construction Site

Abstract

Bridges crossing steep valleys in mountainous regions may be subjected to large angles of attack of the incoming wind flow, because of the complex orography of the region where the structure is located. Therefore, the aerodynamic analysis of bridges in this kind of regions should account for this peculiarity. In this paper, the aerodynamic characterization of a bluff deck section of a railway bridge, with angles of attack ranging from −6 to +6° is discussed. It is shown that standard analyses that consider only angles of attack near 0° only are not sufficient to ensure optimal aerodynamic performances. Indeed, with such large angles of attack the flow field near the deck may change consistently, also leading to aeroelastic instabilities or strong vortex-induced vibrations. To mitigate the aeroelastic issues, without an abrupt change of the deck section, several aerodynamic appendices were tested, and a tailored section with acceptable behavior was selected.