Eiki Shinochi

Predictive analysis of bridge girder acting force linked with storm surge simulation

Fuminori NAKAMURA

Recently, many structures have been damaged by natural disasters such as earthquakes, tsunamis, and storm surges. In particular, storm surge has the problem that the prediction method of the external force acting on the bridge has not been established. In this study, for the purpose of establishing a general-purpose method for predicting storm surge wave forces acting on bridges, we constructed a prediction analysis model for wave force on the bridge girder linked with storm surge simulation technology. In addition, the validity of the constructed model was verified by carrying out the reproduction analysis of the storm surge phenomenon that occurred in the past.
This model takes into consideration the shape of the bridge girder and topographical conditions in a general way, reproduces the weather, waves and tidal fluctuations around the bridge, and can integrate and calculate the wave force on the bridge girder accordingly. To validate the model, we used the results of surveys of storm surge events and bridge collapse conditions caused by Hurricane Katrina in 2005.
As a result, it became clear that the time-series trend of fluctuations in the calculation results from the storm surge prediction model generally matched the observed values of past storm surge phenomena. In the calculations of the wave force acting on the bridge girder revealed that the wave force of a storm surge greatly depends on the height of the bridge girder, the wave height, and the tide level, and that the wave force is maximized when the water level is below the girder. This can reproduce the damage caused by Katrina, and it was clarified that the waves generated by the storm surge phenomenon and the accompanying fluid external force on the bridge can be reproduced in general.
From the above results, it was shown that the external force prediction model for bridge girders corresponding to storm surge phenomena developed in this study can predict storm surge phenomena around bridge girders and wave forces acting on bridge girders with high accuracy.