Bending Proof Load as a Quality Control for Compression Parallel-to-Grain in Lumber

Abstract

ABSTRACT AN experiment was conducted on 400 pieces of No. 2 Dense KD Southern Pine to determine the effect of proof loading on compressive strength parallel-to-grain. A treatment sample was reverse proof loaded in bending about the strong axis to 12.41 MPa (1800 psi). The survivors were tested to failure in compression parallel-to-grain. Compressive strength of the treatment sample was compared to that of an untreated control sample. The estimated mean of the parallel-to-grain compressive strength for the treatment sample was 7.4% higher than the control sample. The 5th percentile of each distribution was estimated by fitting the lognormal distribution to the data sets. While the treatment sample 5th percentile was estimated to be 6.7% higher than the control sample, it was concluded that such a difference is insignificant.