A study on impulsive force of timber drifted by tsunamis

点击翻译按钮获取中文摘要

A procedure is developed for predicting the maximum impulsive force on structures with an arbitrary opening ratio due to the collision of timbers drifted by bore or surge front formed by tsunamis. In the course of the developments, variation features of the apparent inertia coefficient, the moving velocity and the impact duration time of timbers with the opening ratio, the relative bore or surge height and the timber's slenderness ratio are examined, experimentally.Two theories are also developed for estimating the impulsive force on structures due to the collision of timbers drifted by a flow with relatively weak unsteadyness and fluidity compared with bores or surges, based on the elastic wave or elasto-plastic theory. In the former, the elastic wave theory is applied to the timber and the structure, and the mass conservation law and the Bernoulli's theorem are applied to the water which is left between the timber and structure and has a shock absorption function. In the latter, the elasto-plastic theory is applied to the timber, and the angular revolution velocity and the collision angle of the timber and the deflection of the structure are also considered.