STRENGTH AND STIFFNESS PROPERTIES OF SMALL CLEAR SPECIMENS TAKEN FROM COMMERCIALLY PROCURED NO.2 2×8 AND 2×10 SOUTHERN PINE DIMENSION LUMBER
Keywords:southern pine, mechanical properties, modulus of elasticity, modulus of rupture, small clear specimens, lumber, strength, stiffness
AbstractThis technical note focuses on the modulus of rupture (MOR) and modulus of elasticity (MOE) of small clear southern pine (Pinus spp.) test pieces cut from commercially procured full-size lumber specimens. A production-weighted sample of 476 No.2 grade 2×8s and 2×10s was acquired from retail establishments throughout the southern pine producing region. The specimens were subjected to static bending tests to measure MOR and MOE. From 447 of those specimens, a single small clear beam (3.8 × 3.8 × 61 cm) was extracted and subjected to a static bending test of the same properties. Two-sample t tests showed no evidence of statistical difference in either mean MOE or MOR between the small samples taken from the 2×8s and the 2×10s. Bivariate correlations and r2 values showed an overall weak relationship (r = 0.30, r2 = 0.09) between the small clears and their parent specimens in respect to MOR. A more moderate relationship (r = 0.60, r2 = 0.36) was found in respect to MOE between small clears and their parent specimens. In addition, a relatively strong relationship was found between the MOR and MOE values of the small clears themselves (r = 0.77, r2 = 0.59). It is intended that subsequent publications will examine similar relationships in other grades and sizes.
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