Abstract
A mechanism of the tsunami effect on Miyako Bridge which was survived from the 2011 Tohoku tsunami was discussed based on the video picture and the numerical analysis. The video picture clearly showed the tsunami was approaching to the Miyako Bridge with a slight angle of the tsunami wave front and the bridge was inundated with the tsunami. The analytical results showed that the maximum horizontal and vertical tsunami-induced forces were generated by the hydrodynamic pressure at the overhang, the girders when the tsunami wave acted to the superstructure. It was also suggested from the practical estimation that those forces could not wash-away the superstructure of the Miyako Bridge, which coincided with the actual performance of the bridge after the 2011 Tohoku tsunami.
