Abstract
Shear tests parallel to the grain were conducted on domestic wood samples with different growth ring orientations. Shear strength was dependent on the angles between the direction of growth ring orientation and the applied force. The maximum shear strength showed at the intermediate growth ring orientations. Results of shear tests were also used to modify the formula which had previously been developed to predict the withdrawal strength of screw on the face of lumber. Predicted equations were fitted to the results of previous study with different length of No. 8 screw. Predicted equation was under-predicted the withdrawal strength of 25 and 30 mm length of screw within 8% and over-predicted withdrawal strength of 18 and 38 mm length of screw. A little differences between the predicted by shear strength with different growth ring orientation and observed values was existed.
연륜경사에 따른 전단강도 실험이 국내에서 생산되는 목재에 대해 실시됐다. 연륜경사는 전단강도에 영향했고, 경사진 연륜에서 최대였다. 전단강도는 나사못 유지력을 예측하기 위한 식에 포함됐다. 나사못 유지력의 예측식은 No. 8 나사못의 실험결과와 비교하여 25 mm와 30 mm 길이에서 8% 이내로 작게 예측되었으나 18 mm와 38 mm에서는 큰 값을 보였다. 전단강도를 사용한 나사못 유지력의 예측값과 실험값 사이에는 연륜경사에 따라 큰 차이를 보이지 않았다.