<資料>サバ産植林木間伐材の性質

Abstract

To invistigate the appropriateness of tropical hardwood thinnings of fast-growing species for structural use, mechanical tests were carried out on bending, shearing and cleavage properties for small clear specimens, and bending properties for full-scale dimension lumbers. The species tested were Acacia mangium (Acacia mangium Willd.), Kamerere (Eucalyptus deglupta Bl.), Gmelina (Gmelina arborea Linn.), and Albizzia (Albizia falcata Backer.). All of these were planted in Sabah, Malaysia, and harvested after 9 years since planting. The results were as follows: 1. An adequate correlation was derived between bending properties (modulus of rupture and modulus of elasticity) and wood density for small clear specimens, and its relationship was similar to that obtained from data on Japanese timbers. 2. The presence of knots and sloping grain reduced the modulus of rupture of dimension lumbers by 13 to 23% when compared to those of small clear specimens, while it affected little on modulus of elasticity. 3. A negative correlation was significantly observed between knot size and the bending strength in dimension lumbers. 4. The allowable stresses calculated through simple formula on dimension lumbers comformed to the criterion of Japanese lumber code for structural use.