Studies on improving mechanical properties and effective application for beams of flat squares obtained from lower part of sugi logs

(1)对杉木大直径原木锯成的平方尺的力学性能进行了测试。结果表明，用锥尺锯一次原木无髓的木材与用中心尺锯二次原木有髓的木材具有几乎相同的性能。(2)为明确弯原木制成的杉木锯材的性能，进行了评价试验。结果表明，对于最大弯曲率约为1-2%的原木（所谓的“B-zai”），考虑到锯切和干燥引起的翘曲，弯曲强度和蠕变挠度，几乎没有实际的障碍来挑选它们作为梁。

(1) Mechanical properties of flat squares sawn from sugi large diameter logs were examined. As a result, it was clarified that the lumber without pith sawn from first logs by taper rule sawing has almost the same properties as lumber with pith sawn from second logs by center rule sawing. (2) In order to clarify the properties of sugi sawn lumber obtained from curved logs, some evaluation tests were carried out. The result showed that, as far as the logs with maximum curved rate of about 1-2% go (so-called “B-zai”), there is almost no practical barrier to pick out them for beams considering the warp due to sawing and drying, bending strength, and creep deflections.