Comparative Study of Tsunami-Like Wave-Induced Forces on Medium-Scale Models of Box Girder and T-Girder Bridges

Abstract

This paper will present a comparative study of tsunami-induced forces on box girder and T-girder bridges, which will be based on component level analysis. Component level analysis can explain the overall loading behavior and can further illustrate the reason for the difference in the forces between these two types of girder. First, in the numerical simulation, a three-dimensional (3D) dam-breaking model (at 1/20-scale) will be developed to generate bore-type tsunami waves. The Reynolds-averaged Navier–Stokes (RANS) equations, combined with the k−ɛ turbulence model will be utilized for the wave simulations. Then, the effectiveness of the numerical model will be verified with the experimental results. The tsunami-induced forces on the box girder and T-girder bridges will be compared and the differences will be discussed in detail based on the component level analysis. In addition, parametric analyses will be conducted to study the influence of the wave momentum flux and still water level (SWL). The results show that: (1) the T-girder bridge witnesses higher and longer-lasting horizontal peak forces. The box girder bridge had significantly larger upward forces than the T-girder bridge, (2) for both type of girders, the upstream web and upstream deck were the major contributors to the maximum horizontal and vertical forces, respectively. Special attention should be paid to the local damage to these components, (3) when the wave is high enough to impact on the whole girder, the differences caused by the girder shape on the horizontal impulse loads can be negligible, and (4) the difference in the vertical impulse loads between these two types of girders continually increases with the momentum flux. For the large momentum flux cases, the vertical impulse loads on the box girder could be 1.7–2.2 times that on the T-type girder.