Stiffness and Strength in Bending of Sugi and Hinoki produced in Mie prefecture

For the study on adequate classification according to the stress grading, the bending tests were conducted on Sugi (Cryptomeria japonica D.Don) and Hinoki (Chamaecyparis obtsusa Endl.) colum of a 105mm square cross-section grown in Mie Prefecture. And, the bending stiffness of commercial square lumber was also invenstigated at the local saw mill. The following conclusions were derived. 1) The distribution of modulus of rupture (MOR) and modulus of elasticity (MOE) was almost the same as that of other prefectures. 2) Current grading system of columm lumber practiced at the saw mill does not always conform to the terms in JAS. 3) Correlation between modulus of repture (MOR) and modulus of elasticity (MOE) of Hinoki column wood was not so high significant compared with that of Sugi column wood. 4) The ratio of maximum knot diameter to the width of the lumber and the ratio of the maximum sum of knot diameter within 15cm length of lumber to the width of the lumber which satisfy the strength estadlished by Building Standard Law is equivalent to those of the first grade in JAS. Therefore, the second grade column lumber is not suitable for bending members. 5) MOR of Sugi and Hinoki column lumber was about the 40% of five percentile significant level of clear wood MOR and the safty index was about 2.5