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The relationship between the collision direction angle and the collision force of woody debris and its behavior is investigated through large-scale bore flow and airborne experiments. In the case of the airborne experiment's oblique collision angle being larger than 20°, the oblique collision force is reduced by up to half of the longitudinal collision force. In the case of the bore flow experiment's initial arrangement along the transverse direction, the wood-log moved with a rotation along the channel floor. Collision forces in the bore flow experiment indicated the trend less than that in the airborne experiment. The effects of water cushioning between the wood-log and vertical wall, and the surrounding water caught by the rotation of debris were considered. Major collision force formulas for collisions in the long axis direction of woody debris are verified through comparison of this study and recent experiments. By considering the reduction in collision energy by the rotational motion of debris after oblique collisions, their collision force formulas are improved to estimate the oblique collision force. The improved formulas can reproduce the reduction of significantly oblique collision forces compared with longitudinal collision forces by the above experiments. The effect of the collision angle's uncertainty on the estimation of the *Corresponding author. 1640022-1 M. !keno et al. collision force was investigated as a case study on a probabilistic evaluation of the collision force.

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Characteristic patterns of tsunami wave pressure on buildings is divided into three types, depending on its vertical profiles and time, which is observed after the tsunami impacted the buildings. The first one is the impulsive pressure, which is observed just after the tsunami impacted the buildings. The second one is the bore pressure, which is observed after the impulsive pressures. The third one is the quasi-steady pressure, which is observed after the bores go away from the buildings. In this study, based on characteristics of bore pressure observed in a hydraulic experiment, a semi-empirical physical model of bore pressure is developed by applying a turbulent bore theory. Also, we present an application method of the semi-empirical physical model to evaluations of bore pressure with usage of numerical results of inundation simulations of two-dimensional nonlinear shallow water equation models. Furthermore, we apply the semi-empirical physical model to evaluations of pressure acting on buildings in an inundation area by carrying out numerical simulations of tsunami inundation.