Experimental Study on the Performance of Underwater Heave Plates for Mitigating Bridge Flutter

This study focuses on the performance of a kind of Underwater Heave Plate (UHP) to mitigate the flutter of long-span flexible bridges. UHPs are suspended beneath the bridge deck by flexible cables, and submerged into water. When the deck vibrates vertically or torsionally under the wind, it hauls UHPs to move up and down in the water. UHPs consume the structure’s mechanical energy and consequently mitigate its vibration. It is important to emphasize that UHPs are used only during rare extreme wind events and do not impact navigation. The control efficacy of UHP with different parameters in mitigating the flutter of two typical decks is experimentally investigated by using wind tunnel and water tank tests. The influence of various parameters (e.g. mass, dimensions, aspect ratio of the plates, and cable stiffness) on the control effect is systematically analyzed. The experimental results demonstrate that the device can effectively increase the onset flutter speed and decrease the vibration amplitude of both soft and hard flutter. Based on some similarity principles, the dimension relationships of the relevant parameters in scaling model tests and actual bridge structures are derived. Several actual bridge examples are provided to illustrate the adaptability of UHPs for controlling bridge flutter. These findings offer valuable guidance for the parameter design of UHPs in practical applications to mitigate bridge flutter.