Investigation of a Stress Class System for No.2 2 by 8 Southern Yellow Pine

The processing of southern yellow pine (Pinus spp.) (SYP) trees into dimensional lumber is a multi-billion dollar industry in the Southeast United States. The finished product is subject to a classic strength assessment procedure known as visual grading. In this study, 484 specimens of No.2 2 inch by 8 inch (nominal) SYP dimensional lumber were visually assessed for strength reducing defects, visually graded by a certified lumber grader, and destructively tested. Destructive testing was performed in accordance with ASTM D4761-13 for modulus of rupture (MOR) and modulus of elasticity (MOE). These results were used to identify parameters which could be significant when developing a potential working stress-class system to improve the efficiency and yield of the specified grade. Six specific visual characteristics were identified that could predict a superior quality product when compared to the current strength and stiffness properties of No.2 2 by 8 lumber