スプルース集成材のヤング係数および曲げ強度における梁背効果

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During 1990's, wood products imported from Europe into Japan have rapidly increased, and major products of them are spruce lumber from northern Europe and so on. The primitive purpose of the study was to assess mechanical properties of these imported lumber and glued laminated timbers (glulams) as structural members for houses. Groups of tested glulams were two: spruce glulams imported from Finland (6sizes) and manufactured glulams using spruce lumber imported from Finland (5sizes). The latter glulams were roughly composed of homogeneous-grade lumber, which were selected according to dynamic Young's modulus values measured by the longitudinal vibration method. Static bending tests were conducted by loading at two one-third points of the span after measuring dynamic Young's modulus by the tapping methods. Dynamic Young's modulus was measured by longitudinal vibration (E_l) and flexural vibration, whose directions were horizontal (E_h) and vertical (E_v) in the direction of the adhesive face of the glulam. For a part of tested glulams, measurements of shear rigidity were done by the torsion vibration method. For the imported glulams, mean MOE was 11.7GPa, but the MOE values were affected by depth/span ratio. The average shear moduli G by static and dynamic tests were 0.581GPa and 0.708GPa, respectively. The best indicator for estimating MOE was E_h among E_h, E_v and E_l based on correlation between MOE and dynamic Young's modulus. For all manufactured glulams, bending tests were conducted by loading at the third points of the constant span. The results showed that the increase of the specimen depth lowered mean MOE and mean modulus of rapture (MOR) for each size. The adjusted MOR were calculated by the standard E conversion proposed by Hayashi, then the adjusted MORs were not apparently influenced by depth. Then we guessed that depth effects on MOR might be very small in case of eliminating effects of shear deformation.
社団法人日本材料学会の論文
2001-07-15

スプルース集成材のヤング係数および曲げ強度における梁背効果

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