Abstract
Any wooden joint shows under compressive stress more or less deformation at its contact plane however tightly it may be jointed. This is evidently due to the fact that the plane of contact is not perfectly flat and, therefore, stresses are concentrated at the hard points of annual ring, which sink into the soft fibers in the opposite plane. The present researches have been done to clarify the behavior of these butt joints, using specimens of Japanese cryptomeria with the size of 10.5×10.5cm. The conclusions obtained are: a) The total deformation at the contact plane of butt joints and skew notches are about 0.55mm under the allowable compressive stresses regardless of the angle of inclination of the contact plane. b) When the wooden specimen is compressed between steel plates, its elastic limit is slightly less than that of the specimen compressed between wooden blocks.
