バットジョイントを有する集成材および単板積層材の引張強度特性
2003 年 52 巻 4 号 p. 341-346
詳細
2003 年 52 巻 4 号 p. 341-346
Tensile strength tests were carried out on various glued laminated wood (GL) and laminated veneer lumber (LVL) with butt-joints (BJ), and size effects of the length of specimens were examined experimentally. In addition, laminating effects which improve strength properties were also examined on the GL. Species used for the specimens were sugi (Cryptomeria japonica D. Don), akamatsu(Pinus densiflora Sieb. et Z.), and Douglas fir (Pseudotsuga menziesii Franco) for the GL, and akamatsu and radiata pine (Pinus Radiata D. Don) for the LVL.
In the case of GL, tensile strength (TS) decreased to 23.5% (sugi), 30.9% (akamatsu), and 18.2% (Douglas fir) of their raw materials. Size effect was evidently observed on the GL, and the reduction of TS by size effect was higher than that of the laminae. Coefficient of laminating effect Κ (ratio of 5% lower extrusion limit after lamination to that of before lamination) on the TS of 2 ply laminated GL ranged from 1.84 to 2.47.
In the case of LVL, the thickness of veneer affected on TS remarkably, and 15 ply type specimens composed of 3mm thick veneer showed higher TS than 7 ply type specimens composed of 6mm thick veneer. Size effect of LVL depended on the thickness of veneer. While 15 ply type specimen showed no size effect, TS of the 7 ply type specimen decreased with increasing the specimen length.
