Improving Suspension Bridge Wind Stability with Aerodynamic Appendages

Abstract

The influence of aerodynamic appendages on the wind stability of box-girder suspension bridges is examined, with special reference to the stability of bridges with very long spans (above 2,000 m). Aerodynamic appendages are winglets eccentrically positioned and running parallel to the bridge axis; winglets can be either fixed to the deck (stationary) or actively controlled. Flutter and torsional divergence analysis are performed using both a 2DOF model and a state-of-the-art multimode coupling procedure. Examples apply to a set of preliminary, defined, hypothetical box-girder suspension bridges with spans of 2,000–5,000 m. Concerning stationary aerodynamic appendages, it is seen that the most promising solution is to locate a winglet only in the leeward position, a possibility originally proposed by the writers. It is also confirmed that the use of active aerodynamic appendages can be a very effective tool in the future to solve the wind stability problems of very long span bridges.