スギ心持ち正角材の外層部接線方向横引張クリープおよび内層部放射方向横圧縮クリープ

概要

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Some creep tests were conducted to clarify the effect of temperature on the drying check of sugi (Cryptomeria japonica D. Don) boxed-heart square timbers during kiln drying. The tensile creep behaviors of tangential direction at the outside layer parts of sugi boxed-heart square timbers and the compression creep behaviors of radial direction at the inner parts of them were investigated.Creep strain and residual strain were larger at 80°C than at 40°C under constant moisture content.Under drying condition, these mechano-sorptive creep strains at 80°C and 40°C were almost same. The creep strains increased approximately like a straight line as the moisture content reduced in the area of moisture content less than 30%. Its gradient can be considered that there is no effect of the temperature. But initial elastic deformation at 80°C was larger than at 40°C. As a result, the relative creep in the high temperature showed lower than in the low temperature. After all, it was supposed that the temperature dependence factor for the restraint of surface check of boxed-heart square timber of sugi was elastic characteristic and was not creep characteristic.The value of creep compliance in compression for the radial direction at the part far from the pith showed relatively low during drying.