Nondestructive Parameters of Lodgepole Pine Dimension Lumber in Bending

Lodgepole pine dimension lumber was collected from seven Colorado and Wyoming sawmills. The sampling included a total of 277 specimens in four visual stress grades. Two testing techniques, one in continuous deflection and the other in transverse vibration, were used to obtain nondestructive parameters. The final phase of testing was a static test to destruction of each piece as a joist under third-point loading. An extensive statistical analysis was employed in testing homogeneous variance, normality, and the goodness of fit of a series of models in order to obtain the best empirical model for the relationship between strength and stiffness. Correlation coefficients ranged from 0.28 to 0.69 in the estimation of MOR. A table is presented showing the relationship for allowable working stresses based on a lower 95 percent tolerance limit as compared to the Western Wood Products Association and West Coast Lumber Inspection Bureau machine grades.

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