Experimental study on tsunami impact on offshore box-girder bridges

To investigate the patterns of wave pressure exerted on the superstructure and substructure of offshore box-girder bridges under the influence of tsunamis, a scale model of 1:25 for both the pier-girder and pier model was constructed for tsunami wave impact testing. The study examined pressure and flow field characteristics at various locations on the box girders and piers under different tsunami wave conditions, analyzing the interaction and mechanisms of tsunami impact pressures between the girders and piers, as well as the effect of impact submersion coefficients on these pressures. The findings indicate significant variations in the degree to which different parts of the box girder are affected, with notably higher pressure at the Girder-Pier Connection (GPC) of the girder's bottom compared to other areas, reaching a differential of 16%. Under conditions where the pier is not submerged, the peak pressure at the top of the pier in the pier-girder model was found to be 40% higher than in the pier-only model. Therefore, ignoring the interaction between girders and piers can lead to an underestimation of the pressures caused by tsunami waves. This research is crucial for identifying bridge failure modes and developing mitigation and protection measures.