FLEXURAL AND TENSILE PROPERTIES OF 2 X 6 AND 2 X 10 SOUTHERN PINE LUMBER : Southenr pine lumber properties

Bending modulus of elasticity (MOE) and tensile properties parallel to the grain were studied on 702 pieces of 2 X 6 and 285 pieces of 2 X 10 No. 2 visually graded southern pine lumber. The overall rings per inch (RPI) in 2 X 6 pieces was 4.82, whereas 2 X 10 had an RPI average of 3.82. For latewood percentage (LW), 2 X 6 pieces found 45.88% of LW and 45.02% for 2 X 10 pieces. Bending MOE (Eb) mean for 2 X 6 was 10,615 MPa, whereas for 2 X 10 lumber, the mean was 13,665 MPa. The tension MOE (Et) mean for 2 X 6 lumber was 11,339 MPa, whereas for 2 X 10 the mean was 9735 MPa. The ultimate tensile stress (UTS) mean for 2 X 6 lumber was 28.42 MPa and the overall mean UTS for 2 X 10 lumber was 24.51 MPa. Linear regression models were useful to explain the relationship between Eb and Et. Strong coefficients of determination (r250.70 and r250.74) were found for both lumber sizes between these two properties. Moderate relationships (r250.43 up to r250.51) between Eb and UTS were also found for both lumber sizes. However, weaker relationships were found between Et and UTS (r250.32 up to r250.40). Three distributions were fit to the Eb, Et, and UTS data and evaluated for goodness of fit. The results suggest that Eb of 2 X 6 lumber might be adequately modeled by a normal distribution, and tensile properties of 2 X 10 lumber might be adequately modeled by a lognormal distribution