Strength of Lumber under Combined Bending and Compression.

Wood members under combined bending and compression occur as structural elements in several important applications as the top chords of trusses, as wall studs, as frame members in towers, and in other rigid frame structures. While strength in bending alone and compression have been extensively studied, the interaction of these two modes of failure is poorly understood, particularly for dimension lumber of common construction grades. The aim of this study was to define a failure locus in the plane of bending moment M versus compressive force C. Attention was restricted to that portion of the plane where bending stress exceeds compressive stress since that is the region of greatest importance in the design of wood frame structures and trussed roofs. In order to limit the scope of the study, only one species Western Hemlock and one size nominal 2 x 6 were studied.