The influence of testing and size variables on the tensile strength of machine stress-rated lumber

In 1981, the Frank Lumber Company and the West Coast Lumber Inspection Bureau initiated a series of studies of variables influencing the assessment of the tensile strength of machine stress-rated (MSR) lumber. These variables included specimen length and width, and pinned versus fixed tensile grips. Four tests with a pinned grip machine and a 4-foot gage length yielded essentially the same results as a fixed grip, 8-foot gage length; the lowest Pelster E segment was always placed between the grips. The MSR grades demonstrated a width effect similar to that for visual grades; however, the MSR relationship accounts for the stiffness segregation of the grading process. Some evidence of a length effect was evident. A characterization of the lowest order statistic of sample sets is presented.

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