Determination of Flexural Strength of Structural Red and White Oak and Hardwood Composite Lumber
Abstract
In this research, flexural properties of mill-run, in-grade red and white oak lumber from a single mill and commercially available laminated hardwood composite were evaluated. Structurally graded green (wet) freshly sawn red and white oak 5 by 10-cm (2 by 4-in) nominal lumber as well as glue-laminated hardwood composite billets were tested in bending and their modulus of rupture (MOR) and modulus of elasticity (MOE) properties were developed. It is well documented that MOR and MOE are two major indicators to evaluate flexural strength of wood lumbers. From these data, summary statistics, design values, and mean separations were calculated and reported. Overall, the red and white oak lumber performed similarly to structural No. 2 grade material. The hardwood composite billets were highly uniform. Each of the three materials demonstrated a reasonably good relationship between MOE and MOR, thereby suggesting that MOE could be used as a selection criterion for strength in a commercial use situation.
Hardwood composite billets on Tinius Olsen machine before (upper panel) and after (lower panel) failure (ASTM D143-14 [ASTM 2017a]).
Red oak lumber on Tinius Olsen machine before (upper panel) and after failure (lower panel) with the type of failure in static bending cross-grain tension (ASTM D143-14 [ASTM 2017a]).
Relationship between modulus of rupture (MOR) and modulus of elasticity (MOE) for (a) red oak, (b) white oak, and (c) hardwood composite billets.
Contributor Notes
The authors are, respectively, Postdoctoral Associate, Graduate Student, Dept. Head and Warren S. Thompson Professor, and Research Associate III, Dept. of Sustainable Bioproducts, Mississippi State Univ., Mississippi State (lk475@mssatte.edu, ajs1189@msstate.edu [corresponding author], rs26@msstate.edu, and fq3@msstate.edu). This paper was received for publication in July 2021. Article no. 21-00051.