Method for measuring the resistances produced on parallel and perpendicular veneers in plywood under nail embedment loading

The resistance of wooden materials against embedment loading is an important property that governs the performance of timber joints with dowel-type fasteners including nails. When plywood is used as a sheet material in a nailed joint, veneers with different grain directions are simultaneously embedded. The resistance produced on individual veneers has to be measured to elucidate the embedment properties of plywood. This study proposes a method for measuring resistance on individual veneers. Embedment behavior was modeled using springs arranged in parallel, and the equations for calculating resistance on individual veneers were derived. Embedment tests were conducted using structural plywood composed of sugi or karamatsu. Mechanical behaviors of individual veneers were revealed as followings. In the initial range of deformation, the slope of the resistance–deformation relationship of the veneer with grain parallel to the load direction is higher than that of the resistance–deformation relationship of the veneer with grain perpendicular to the load direction. The parallel veneer began to yield under a low range of deformation, and the resistance of the perpendicular veneer under a high range of deformation became almost equal to that of the parallel veneer.