著者

友松 昭雄 岡野 健 浅野 猪久夫

出版者

東京大学大学院農学生命科学研究科附属演習林

雑誌

東京大学農学部演習林報告 (ISSN:03716007)

巻号頁・発行日

no.73, pp.p263-275, 1984-01

被引用文献数

1

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A lot of Ezomatsu trees (Picea jezoensis) and Todomatsu trees (Abies sachalinensis) grown in the Hokkaido experimental forest of the University of Tokyo were damaged by the No.15 typhoon in 1981. By the features of the trees in the forest they were classified into three types of damage: a) stem-broken, b) uprooted, and c) survived standing. Twenty-five number of trees of Ezomatsu and Todomatsu, of which diameter were as shown in Table 1, were collected for investigation of wood quality and bending properties. Observation of existence of compression failure, decay, and stain and measurement of bending properties were carried. Results of the observation and the bending tests were discussed in related to the type of damage and summarized as follows. 1. Neither significant difference of specific gravity in air dry nor that of annual ring width was found among stem-broken, uprooted, and survived standing trees. Three fourth of the stem-broken trees of both Ezomatsu and Todomatsu fairly showed decay in the center part of the logs. Consequently the decay will be a cause of stem-broken. 2. Compression failure was observed in the stem-broken trees of three fourth of Ezomatsu, two fourth of Todomatsu, respectively. It was also observed in the uprooted tree of only one fourth Ezomatsu and one fifth of Todomatsu, respectively. But with the case of Todomatsu the failure seemed to be formed by the impact when the tree was uprooted. In the survived standing trees no trace of compression failure was observed. It was observed that compression failures were often around knots and extended tangentially and fairly deeply through radially. 3. No significant difference of bending strength, modulus of elasticity in bending, and absorbed energy in impact bending was observed among the type of damage when test specimens were prepared free from any defects such as compression failure. The values obtained in this research were likely to be identical with those of references, which were absolutely free from any defect or any damage by typhoon. Though little change of modulus of elasticity in bending, compression failure decrease bending strength and absorbed energy in impact bending. Consequently, sawn timber from stem-broken and also uprooted provided with compression failure must not be used as a structural member in construction.