A novel combined countermeasure of fairing-openings for mitigating extreme wave forces on typical coastal low-lying bridges

Abstract

Extreme waves induced by hurricanes have caused severe damages of coastal bridges. However, existing research studies mainly focus on the damage mechanisms under waves rather than effective protection measures. In this study, a novel hybrid countermeasure integrating fairing and openings is proposed for the protection of typical coastal low-lying bridges. A high-fidelity numerical wave flume is established to investigate the performance of this hybrid countermeasure on reducing wave forces. Specifically, interactions between wave and the bridge deck with fairing are analyzed first and the mechanism of fairing in reducing solitary wave forces is elaborated in detail. Then, effects of the fairing shape on reducing wave loads are investigated to facilitate the selection of favorable fairing shape. Thereafter, a hybrid countermeasure is proposed by integrating air venting holes with the optimal fairing shape, whose performance under various wave heights is studied accordingly. Results show that the installation of fairings alone can reduce the horizontal force on the bridge to some extent, yet its effects on reducing the vertical force are negligible. In contrast, when the wave height is higher than 1.8 m, the proposed combined measure can effectively reduce both vertical and horizontal wave loads on the bridge, thus desirably protecting the structural safety of coastal bridges.