To evaluate the effects of impermeable rigid buildings located near vertical quay walls on the reduction of the inundation water volumes due to run-up tsunamis, a full-scale three-dimensional numerical analysis is performed using a three-dimensional coupled fluid-structure-sediment interaction model. Numerical results show that the inundation water volume can be reduced with an increase in the shielding ratio of the long-shore width of the buildings with respect to the total width of the coastline, and accordingly the buildings located along the coasts have the reduction effects of the inundation water volume. This suggests that countermeasures against tsunamis can be evaluated in a\ud
comprehensive manner in terms of not only shore protection facilities for tsunamis at relatively high frequencies but also such buildings. Furthermore, the inundation depth at the seaward side of the buildings and the cross-shore bottom flow velocity at the gaps between the buildings increase with the shielding ratio, suggesting an increase in tsunami force and the onset of local scouring when the shielding ratio is large. Consequently, when designing buildings along the coasts, it is essential to consider an appropriate balance between the reduction effects of the inundation water volume and the instability of the buildings caused by the tsunami force and the local scouring
