집성재의 핑거길이가 휨강도성능에 미치는 영향

The Effect of Finger Length on Bending Strength Properties in Laminated Wood

This paper describes the bending strength properties of laminated woods which had three kinds of specimens according to finger length-l2, 4.5 mm and butt joint and the acoustic emissions (AEs) generated during the test. 3-ply laminated wood beams were tension side layers (lower layers) composed of one middle lamina and two side-jointed laminae, with one butt joint (IBJ), one finger joint (12mm, ₁FJ₁₂) or one finger joint (4.5mm, ₁FJ45) in the middle lamina of tension side layer. And 3-ply laminated wood beams were tension side layers (lower layers) also composed of one lamina, with one butt joint (BJ), one finger joint (12mm, FJ₁₂) or one finger joint (4.5mm, FJ45) in tension side layer. Cryptomeria pieces were cut for butt and two finger types and glued with resorcinol-phenol resin adhesive. The results were as follows: It was not effective in the bending modulus of elasicity (MaE) with IFJL type and had no difference from finger length. The bending modulus of rupture (MOR) of laminated wood beams including finger joint was the same values as that including butt joint and had no difference from finger length. It was effective in MaE with FJL type and had no difference ITom finger length. The effect of finger joint on MaR was much higher than that of butt joint but had no difference ITom finger length. The AE generation time of 1FJL type was earlier than that of the control wood and the number of AE count was much more than that of the control wood. However, the AE generation time of FJL type was earlier than that of the control wood and the number of AE count was much fewer than that of the control wood.