Shohei KIRIMOTO

Investigation for establishing a judging method of outflow on bridge girders due to tsunami and its effectiveness

Takumi SHIMOMURA

On March 11th in 2011, Earthquake of Tohoku Region Pacific Coast occurred.The tsunami generated from this earthquake, cause many damages in bridges by outflow and it is also, predicted that the same problem will occur at next Nankai Trough earthquake, expected to occur in a near future.
For this earthquake, tsunami hazard maps have been established in Japan to simplify and make more efficient t the method of outflow judgments of bridge girders.Therefore, the purpose of this study was to establish a judging method of outflow of bridge girder using these tsunami hazard maps  throughout the whole country.
In order to do this,  a numerical analysis of fluids considering pressure acting on the bridge girder in free water surface was performed to examine the tsunami force action.Furthermore, a method of judging the outflow of bridge girders considering the flow velocity and flooding depth obtained from the hazard map, was investigated.
Following the results from numerical analysis of fluid, a new judging formula for quantify the outflow of bridge girder was developed.Also in this formula, was added the action of horizontal force action reported onon previous researches, and the lifting force action in the vertical direction of the girder.
Additionally, Great East Japan Earthquake of 2011 at Rikuzentakada area and kesennuma area was analyzed and using these results, validity of the proposal method was verified.As a result, the proposal method of this work applied to Great East Japan Earthquake of 2011, shown that the outflow status of the bridge girder can be simulated roughly.