Experimental and numerical investigation of combined countermeasure for mitigating tsunami forces on typical coastal T-girder bridge deck

Abstract

Tsunamis can cause destructive damage to coastal bridges resulting in huge economic losses and human casualties. Different types of countermeasures can reduce the horizontal and vertical uplift forces of tsunami on coastal bridges, thus protecting them from tsunami damage. However, previous studies have mainly focused on a single measure for the bridge deck. This study concentrates on the integrated countermeasure of the fairing and opening holes on typical coastal T-girder bridge deck. The effect of the integrated measure on reducing tsunami forces under different tsunami bore conditions is investigated through experiments and numerical simulations. The optimal fairing shape is also examined using an adaptive machine learning based technique. Results show that: (a) The openings on the bridge deck can effectively reduce the vertical uplift tsunami forces on the T-girder, but will slightly increase the horizontal tsunami forces on it; (b) With installation of the fairing only, the horizontal force on the T-girder can be effectively reduced due to the diversion effect of the fairing; however, in some cases, this measure will adversely increase the vertical uplift tsunami force on the T-girder; and (c) The combination of the fairing and opening-hole countermeasures for tsunami has a favorable mitigation effect on both horizontal and vertical uplift forces applied to the T-girder bridge deck. The mitigation effect increases beneficially with the increase of the tsunami bore wave height for the studied cases.