Strength of small-diameter round and tapered bending members

Abstract

An early focus on structural use of processed rather than round timber resulted in an underestimation of the structural advantages of retaining the natural form of small-diameter round timber. In the round and tapered form, timbers are not susceptible to the strength-reducing effects of diving grain and exposed juvenile wood. Fiber continuity around knots on the surface of a debarked log rarely exhibits the stress concentration and fracture propagation commonly seen in disrupted grain around knots in lumber. Symmetry of material properties about the centroidal axis in a round timber improves the efficacy of standard section property equations derived for uniform isotropic materials. Ignoring these benefits and comparing the strength of round and processed timbers solely on the basis of section property, the round section has from two to fourtimes the bending load design capacity of any standard-sized processed timber that could be sawn from it.

Citation

Wolfe, Ron; Murphy, Joe. 2005. Strength of small-diameter round and tapered bending members. Forest products journal. Vol. 53, no. 3 (Mar. 2005): Pages 50-55