高温乾燥により生じた材面割れ深さがスギ平角実大村の強度性能に及ぼす影響

摘要

The objective of this study is to clarify the effects of a surface check caused by conventional high-temperature drying (HTD) on the strength property of various sections in beams of sugi (Cryptomeria japonica). The height and length of the beams ranged from 15 to 36 cm and from 3 to 6 m, respectively. The average depth of checks caused by HTD was 13 ± 9 mm. No significant differences between beams with non-surface checks and those with surface checks caused by HTD were found in the bending properties, such as the modulus of rupture (MOR) , modulus of elasticity (MOE) , bending work, and Janka plastic modulus. In addition, to clarify the effects of a surface check depth on the strength property of the beams, slits with various depths (30, 50, and 70% in width) were artificially processed along the neutral axis of the beams. Although the depth of the slits along the beam did not affect the dynamic Young' s modulus or MOE, a slit depth of more than 50% gave a significant decrease of MOR. Dynamic shear modulus and shear strength were significantly decreased with a slit depth of more than 30% . It is concluded that surface checks caused by conventional HTD do not affect the bending and shear properties in beams.%最近,在来木造住宅における梁桁などの横架材にスギ平角材を用いることが期待されている1）.横架材は,鉛直荷重及び水平力を負担し,構造体を支える重要な役割を持つことから2）,柱材よりも,さらに厳密な強度性能が求められる.