Abstract
Kitayama polished log is an useful lumber for construction materials of japaneue arxhitecture produced from North-west district of Kyoto city, and is one race of sugi (Cryptmeria japonica D. Don.). This wood is restrained from growth by frequent pruning for special purpose during its growing period. This experiment was attempted to research the superiority in strength properties of Kitayama-sugi. The results obtained by this test are as follows.
(1) Compression strength: Kitayama-sugi is stronger 18-30% than normal sugi.
(2) Beding strength: Kitayama-sugi is stronger 56-62% in bending strength and larger 10-43% in Young's Modulus than normal sugi.
(3) Impact bending work: Kitayama-sugi is larger 54-114% than normal sugi.
(4) The relations between density of annual rings and specific gravity, between density of annual rings and summer wood percentage are shown in fig. 1.
(5) The relations between density of annual rings and bending strength, between density of annual rings and Young's Modulus are shown in fig. 2.
(6) The relations between summer wood percentage and bending strength, between summer wood percentage and Young's Modulus are shown in fig. 3.
