2025 Volume 71 Issue 2 Pages 58-66
Using sugi (Japanese cedar, Cryptomeria japonica) nominal size of 210, various Young's modulus against the Japanese agricultural standards for structural lumber and finger-jointed structural lumber for wood frame construction (JAS 0600), and bending strength were examined. The Young's modulus of the sugi nominal size of 210 was roughly determined by measuring the Young's modulus of the log. The longitudinal vibration method and flexural vibration method can be substituted for the measurement of Young's modulus by the grading machine, which is the current method of quality control in machine stress-rated (MSR) framing lumber of JAS 0600. Edgewise bending test results indicated that most of the specimens were classified as select structural grade of the A class, and that the majority of these specimens met the design strength criteria for select structural grade of the A class. When logs were sorted by Young's modulus by the longitudinal vibration method, MSR-grade was high enough to be used as horizontal structural members, proving the effectiveness of log sorting.
