Bowtie Beams: Novel Engineered Structural Beams from Southern Pine Lumber

Maisaa Kakeh, Joseph Dahlen, Rubin Shmulsky, P. David Jones, R. Daniel Seale


The intersection of decreasing resources and increasing population and its associated demands creates a need to develop alternative products to solid sawn lumber. This research used a modified form of sawn southern pine (SP) lumber in which cants were sawn into symmetrical double-trapezoidal shapes and glued together to form a bowtie beam. The result was a cross-sectional shape that was widest at the beam flanges and narrowest at the neutral axis. Cants were cut from logs and sawn into trapezoids, nondestructively tested, glued into the bowtie beams, and nondestructively and destructively tested to determine mechanical values as per ASTM D4761. The objectives of this study were to manufacture composite bowtie beams and to conduct nondestructive and destructive testing on the beams. Overall, the bowtie beams compared favorably with strength properties of No. 2 SP lumber of roughly equivalent size to the bowtie beams. The bowtie beam shows promise as an engineered product because a minimal amount of capital and technology is needed to process small-diameter trees into this value-added product.


Southern pine;lumber;composite beam;structural beam;wood utilization;laminated wood;novel composite beam

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