Numerical investigation of tsunami wave impacts on different coastal bridge decks using immersed boundary method. (1st April 2020)

• Record Type: Journal Article
• Authors: Zhao, Enjin; Sun, Junkai; Tang, Yuezhao; Mu, Lin; Jiang, Haoyu
• Is Part Of: Ocean engineering. Volume 201(2020)
• Publication Date: 2020-04-01
• Subjects: Tsunami-like wave -- Solitary wave -- Bridge -- Air vent -- VOF -- Hydrodynamic loads; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2020.107132
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: Due to the strong interaction between the bridges and the extreme waves generated by hurricanes and tsunamis, many coastal bridges were damaged in the past few decades. In this study, in order to investigate the effect of the extreme wave on a bridge, tsunami-like wave generated based on record in the Iwate station during 2011 Japan tsunami event instead of solitary wave is employed to impinge on the bridge with or without air vent. According to the Computational Fluid Dynamics (CFD) theory with a Volume of Fluid (VOF) interface tracking approach, a Numerical Wave Tank (NWT) is developed, in which the Immersed Boundary (IB) method is referred to simulate fluid and structure interaction. The model is calibrated with the experiment. In this numerical tank, the effects of tsunami-like waves with different prominent conditions including wave height and submersion depth on the bridges are studied. Besides, the efficiency of air vent in reducing the hydrodynamic load is also discussed. The results indicate that when the tsunami-like wave overtops the bridges, a noticeable overtopping, where the flow injects into the water fiercely and the whole flow field is very chaotic, is observed. The vertical forces on the bridges are larger than the horizontal forces, leading to many decks to collapse between two piers with small lateral displacement after the hurricanes and tsunamis. After the tsunami-like wave passes over the bridge, the oscillation of the residual wave causes the load oscillation of the bridge. The position of the bridge relative to the initial sea level has a serious impact on the forces on the bridge when the tsunami-like wave passes through it. With the increase of the wave height, the interaction intensity between the tsunami-like wave and the bridge is enhanced and the forces on the bridge also increase, but the effect duration reduces. After the air vent is installed, air vent can reduce the forces on the bridge and improve the efficiency of the bridge protection. Highlights: A numerical wave tank is developed for the generation of tsunami-like wave instead of solitary wave.. The effects of tsunami-like waves with different heights on the bridges are investigated. The efficiency of air vents installed on a bridge in reducing the hydrodynamic loads under tsunami-like wave is studied. The influence of the bridge location relative to the still water surface on the hydrodynamic load is investigated.