Flexural and Tensile Properties of 2x6 and 2x10 Southern Pine Lumber

Abstract

Bending modulus of elasticity (MOE) and tensile properties parallel to the grain were studied on 702 pieces of 2 × 6 and 285 pieces of 2 × 10 No. 2 visually graded southern pine lumber. The overall rings per inch (RPI) in 2 × 6 pieces was 4.82, whereas 2 × 10 had an RPI average of 3.82. For latewood percentage (LW), 2 × 6 pieces found 45.88% of LW and 45.02% for 2 × 10 pieces. Bending MOE (E_b) mean for 2 × 6 was 10,615 MPa, whereas for 2 × 10 lumber, the mean was 13,665 MPa. The tension MOE (E_t) mean for 2 × 6 lumber was 11,339 MPa, whereas for 2 × 10 the mean was 9735 MPa. The ultimate tensile stress (UTS) mean for 2 × 6 lumber was 28.42 MPa and the overall mean UTS for 2 × 10 lumber was 24.51 MPa. Linear regression models were useful to explain the relationship between E_b and E_t. Strong coefficients of determination (r² = 0.70 and r² = 0.74) were found for both lumber sizes between these two properties. Moderate relationships (r² = 0.43 up to r² = 0.51) between E_b and UTS were also found for both lumber sizes. However, weaker relationships were found between E_t and UTS (r² = 0.32 up to r² = 0.40). Three distributions were fit to the E_b, E_t, and UTS data and evaluated for goodness of fit. The results suggest that E_b of 2 × 6 lumber might be adequately modeled by a normal distribution, and tensile properties of 2 × 10 lumber might be adequately modeled by a lognormal distribution.

Citation

Uzcategui, Marly G.C.; Franca, Frederico J.N.; Seale, R. Daniel; Senalik, Christopher Adam; Ross, Robert J. 2022. Flexural and Tensile Properties of 2x6 and 2x10 Southern Pine Lumber. Wood and Fiber Science. 54(4): 257-269. https://doi.org/10.22382/wfs-2022-24.