USING NONDESTRUCTIVE TESTING TO IDENTIFY PREMIUM GRADES IN SOUTHERN PINE AND DOUGLAS-FIR UTILITY CROSSARMS
Keywords:crossarms, strength, bending, modulus of elasticity, modulus of rupture, southern pine, Douglas-fir, nondestructive, grading
Unlike lumber, wood utility crossarms are not currently available in premium grades that indicate a higher level of performance in service. Previous research has shown that nondestructive testing (NDT) techniques are able to predict performance properties of solid wood products with considerable accuracy. The aim of this study was to determine the suitability of NDT methods for predicting the stiffness and strength properties of wood utility crossarms and possibly aiding in the identification of a premium grade that exhibits higher average performance values. Samples of Douglas-fir and southern pine were subjected to multiple NDT technologies to estimate modulus of elasticity (MOE). Each specimen was also measured for MOE and modulus of rupture (MOR) with a static bending test. Bivariate correlations and corresponding R2 values showed that Fibre-gen’s Director HM200 and Metriguard’s E-computer were the most accurate NDT devices among those tested for predicting both MOR and MOE. Means tests also suggested that the devices could possibly be used to identify a premium grade that shows significantly higher average performance values.
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