Two-Species Laminated Beams

This paper sets forth the simple theory of two-species wooden beams incorporating high-strength heavy outer laminations or “flanges,” together with low-strength lighter cores into glued laminated members having high strength and high stiffness. Expressions for transformed section, ratio of core depth to over-all depth, and shear at the neutral axis are derived. A few beams made of Douglas-fir outer laminations, and No. 1 or No. 2 common eastern-spruce cores were tested and their strength properties determined. Their performance coincided quite well with that predicted by the theory. A “form factor” similar to that for wooden I-beams may be involved.