Masahiro WATANABE
Proposal of Tsunami Disaster Prediction Method and Effect for Disaster Mechanism of Bridge Girder
Yasushi TANAKA, Taro ARIKAWA
14% of the bridge girder of tsunami inundation area is subjected to spill damage by tsunami triggered by the Great East Japan Earthquake of March 2011. In the study of the past, Shiraishi and others performed damage analysis by the resistance of the bridge girder and the ratio of the tsunami force. As a result, the evaluation technique was not able to evaluate the damage of the bridge appropriately. They said that the damage prediction precision of the bridge girder improves by predicting velocity appropriately. In this study, firstly, we clarified force to act on a bridge girder by physical experiments. Next, we calculated velocity to act on the bridge girder by tsunami run up analysis using STOC, and predicted the damage of bridge girder.
From the result of the physical experiment, we clarified that horizontal force and down force increase with increasing velocity under conditions of the steady flow. And we suggested a formula for computation of a drag coefficient and the lift coefficient under conditions of the steady flow.
We performed tsunami run up analysis for bridges of the tsunami inundation area to get velocity to act on bridge girder and water level elevation. We performed the damage prediction of the bridge by empirical formula of a drag coefficient and the lift coefficient and velocity by tsunami going up analysis. As a result, the predictive precision improved more as a result of past by using this technique. We think that the damage prediction precision of the bridge improves by considering the effect on drag coefficient and lift coefficient by the form of the bridge girder.
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