Full-Scale Experimental Study of Impact Demands Resulting from High Mass, Low Velocity Debris

Abstract

Tsunamis can generate a considerable amount of flow velocity on land. The associated hydrodynamic effects coupled with the plethora of unrestrained objects and frangible structures produce significant debris that can travel similar velocities as the flow. Design of structures to resist the tsunami-driven debris requires a conservative estimation of the forces generated at impact. To quantify the forces generated, an experimental study was conducted on a full-scale wood utility pole, steel tube, and ISO shipping container subjected to in-air axial impacts. The impact force is found to vary linearly with the impact velocity and the impact duration remains constant for elastic response of the debris. For inelastic axial impact of the debris, the duration of the impact event increases and the impact force demands reach a limit. The results are compared with a simplified method, which is found to provide an accurate estimate of the impact demands. The model presented in this paper is developed for use in design guidelines to define debris impact forces and durations for design.