1. 2007 IUFRO Division 5 Conference Taipei 5.02.00 Physiomechanical properties of wood and wood-based materials and their application Chih-Lung Cho Department of Natural Resources National I-Lan University Forest Product and Environment: A Productive Symbiosis

2. Mechanic Properties of Structural Lumber Produced from Thinned Wood of Japanese Cedar Grown in Taiwan Chih-Lung Cho*, Li Chwen Lin, Jiunn Haur Chen, Huey Lan Wang National I-Lan University Department of Natural Resources No. 1, Sec. 1, Shen-Lung Rd. 260, I-Lan Taiwan, R.O.C Department of Natural Resources National I-Lan University Forest Product and Environment: A Productive Symbiosis

3. Department of Natural Resources National I-Lan University Aim of study and methods In order to understand the mechanic properties and lumber grade of structural lumber produced from thinned log of Japanese cedar grown in Taiwan by using: Visual grading and mechanical stress grading Edgewise transversal vibration and bending test methods for measuring stiffness and MOR of lumber

4. Department of Natural Resources National I-Lan University Results Mechanical properties of visual and mechanical stress grade lumber Visual grades Density (kg/m 3 ) MOE(GPa)MOR(MPa) Allowable bending stress(MPa) Construction4449.0349.5115.57 Standard4427.8144.0012.17 Utility4487.7842.8812.13 Below grade4488.3142.8310.73 Mechanical stress grade E be (GPa) Allowable bending stress (MPa) E54-611.65 E76-814.26 E98-1017.23 E1110-1220.57 E1312-1422.08

5. Department of Natural Resources National I-Lan University Conclusions Vibration technique is suitable used for on-line mechanical stress grading operation system. Establishment of allowable bending stress of Japanese cedar could make more efficient use of the available timber resource in meeting timber structure requirements.