SEDL / STP / STP353-EB / STP45112S

Stress-Grading Method for Dimension Lumber

McKean, H. B.
Director of Research and Assistant Director of Research, Potlateh Forests, Inc., Lewiston, Idaho

Hoyle, R. J.
Director of Research and Assistant Director of Research, Potlateh Forests, Inc., Lewiston, Idaho

Pages: 16    Published: Jan 1964

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Abstract

The modulus of elasticity (MOE) is a mechanical property of wood that can be measured rapidly and nondestructively. Research to establish relationships between MOE and modulus of rupture of commercial lumber has been conducted for five principal species of wood. Typical results are presented in this paper. The influences of a variety of interacting wood property characteristics are discussed. It is determined that the effective MOE of lumber containing normal defects of the commercial grades can be used effectively as a structural grading criterion.

The principal features of a machine for rapidly measuring MOE are described. Results of tests showing the correlation of rapid grading machine measurements and standard universal testing machine measurements are reported. Grading rules and grading machines based upon the research described in this paper are in commercial use and operation.