Experimental investigation of tsunami-borne debris impact force on structures: Factors affecting impulse-momentum formula

This study investigates factors affecting tsunami-borne debris impact force on structures. Debris collision accelerations were measured at the contact point on the structure's seaward wall using disc- and box-shaped smart debris devices; the equation of motion was used to estimate the debris impact forces from the measured accelerations. Also, the impact force was measured at the base of the structure using a multi-axis load cell, and compared with the forces determined using the smart debris devices. The basic impulse-momentum formula was modified by the addition of coefficients, taking into account the added mass and the debris velocity. Debris shape also influenced the impact force. Deformability of the debris and flexibility of the structure both reduced the debris impact force.