抄録
Bending tests were done for ten specimens of tapered wood beam made of Japanese cedar and SPF to find splitting failure loads, and simultaneously tensile and shear tests of coupons cut from the same timbers were done to find material properties. It was verified that the splitting failure takes place when the maximum radial stress along the taper edge, which is derived from stress-function theory, reaches the tensile strength of the wood with the same angle to the grain as the taper of the beam. The well-known methods after Hankinson, Norris, and Tsai-Hill were applied to calculating the tensile strengths at various angles to the grain from the basic strengths parallel and perpendicular to the grain of orthotropic material. It was found that Norris and Tsai-Hill formulae are both available to give a good prediction, while Hankinson formula shows a larger dispersion.
