Abstract:

In this paper, bending and compression ingrade tests were conducted on 45 mm×90 mm×2 600 mm dimension lumber made of Cunninghamia lanceolata plantation according to GB/T 50329，ASTM D4761 respectively. The results showed that average bending modulus of elasticity（MOE）,average bending modulus of rupture（MOR）,average compression strength parallel to the grain（UCS） of dimension lumber presented such similar trend as SS grade the highest, then No.2, No.1 the least. As far as SS,No.1,No.2 grade was concerned, characteristic value of MOE was 10.34，9.87，10.17 GPa respectively, characteristic value of MOR was 26.93,20.25，20.74 MPa respectively, characteristic value of UCS was 21.59，20.64，20.33 MPa respectively. In addition, the ratio of UCS to MOR ratio decreased when MOR increased. When full size test results were compared with that of small clear specimen, it was found that average MOE of SS,No.1, No.2 grade of the former was 1.13, 1.08，1.12 times the latter, average MOR of the former was 84.8%, 70.8%，78.7% of the latter, average UCS of the former was 81.1%, 74.3%，75.9% of the latter.

Key words: Cunninghamia lanceolataplantation, dimension lumber, in grade test