This study aims to investigate collision forces of drifted objects due to tsunami acting on cylindrical structures. The hydraulic experiments were conducted to investigate the characteristics of collision forces to columns. Through hydraulic experiments, it is clearly confirmed that the peak values of collision forces depend on the rigidity of drifted objects. This result suggests that when the drifted object has low rigidity such as cars or boats, the collision forces acting on structures are relatively small. The numerical simulation of collision forces of a drifted car to column structures were also conducted by using a 3-D simulation model based on SPH method. The simulation results show that the behavior of the drifted car and collision forces are simulated qualitatively well.
