An Emergency Aerodynamic Measure to Suppress Vortex-Induced Vibration of Bridge Decks: Suspended Flexible Sheets

This paper proposes a novel emergency aerodynamic measure, i.e. suspended flexible sheets (SFSs) with high strength, to suppress the vortex-induced vibrations (VIV) of bridge decks. The cost of the SFSs is very low, and the SFSs can be readily installed for an operational bridge in a short time. The control effectiveness of the SFSs is tested for a bluff box girder using wind tunnel experiments (the model scaling ratio is 1:36 and the range of Reynolds number is 1.71 x 10(3) to 1.12 x 10(5)). The relevant parameters of the SFSs (installation location, height, counterweight form, and arrangement form) are systematically optimized. The experimental results show that the in-wind postures of the SFSs are critical for the control performance. The random waving of SFSs can disturb the airflow around the bridge deck at the lower surface, weaken the interaction between the vortex shedding from the upper and lower surfaces, and hence reduce the VIV response. The control performance of the aerodynamic measure can be significantly increased by using appropriate arrangements of the SFSs and counterweights. For the tested cases, the maximum reduction ratio of the VIV amplitude approximately reached 2/3.