Mitigating tsunami forces on T-shaped girder bridges: Numerical analysis of a novel breakwater-fairing combination

Tsunamis can pose a significant threat to all infrastructure in their path. This study explores the effectiveness of a novel strategy combining a breakwater with fairing (a specific type of deflector) to mitigate tsunami risks on Tgirder, utilizing two-dimensional numerical simulations. The key findings of this research are as follows: (a) The breakwater effectively reduces tsunami wave energy, as evidenced by decreased wave height and velocity across various scenarios after interacting with the structure. The innovative combination of the semicircular breakwater and fairing demonstrates superior performance compared to four other breakwater-fairing combinations in reducing tsunami forces on T-shaped girder bridge decks. (b) In the numerically simulated scenarios, increasing the gap between the breakwater and girder results in a significant decrease in tsunami-induced forces. (c)The breakwater-fairing combination shows remarkable effectiveness in mitigating tsunami forces under diverse wave height conditions. (d) This study extends the tsunami force calculation formula (proposed by Wu[1]) for Tshaped bridge girders. The existing formulas are applicable for tsunami wave velocities ranging from 2 to 10 m/s and wave heights of approximately 2 to 8 m, where the structure remains initially unsubmerged. Through least squares fitting, new equations are derived for scenarios involving fairings alone and those incorporating both fairings and breakwaters. This study provides valuable insights and promising avenues for employing breakwater-fairing combinations as an effective measure to protect T-shaped girder bridge decks in coastal areas from tsunami damage.