| This paper discusses tsunami induced hydrodynamic forces applied to various bridge sections through hydraulic experiments. The hydraulic experiments were conducted using bridge models with rectangular, trapezoidal, inverted trapezoidal, hexagonal, and mixed rectangular/semicircular (modified rectangular) cross-sectional geometries. During the experiments, the flow pattern around the models and the tsunami hydrodynamic forces were observed. The results showed that the trapezoidal, hexagonal, and modified rectangular section models were subjected to less horizontal hydrodynamic force than the rectangular section model. Further, it was shown that the trapezoidal and modified rectangular models were subjected to low lift forces, and that the tri-component force coefficients of all tested models were nearly constant regardless of the inundation depth of the wave. Additionally, the effect of countermeasure work performed on a plate girder bridge model was discussed. It was determined that even though the horizontal force could not be reduced significantly, vertical lift force could be reduced by installing baffle plates to the girders, thus reducing the risk that the bridge might be destroyed by a tsunami. |
