Accessible Requires Authentication Published by De Gruyter February 23, 2017

Nondestructive bending tests on Douglas-fir utility poles as a potential tool for pole sorting and for prediction of their behavior in service

Milo Clauson, Jeffrey J. Morrell, Bennett Romanaggi and Arijit Sinha
From the journal Holzforschung


Wood poles are a critical part of the electrical transmission system in North America. Wood poles are normally selected on the basis of visual features such as knots, slope of grain or other defects, but there is currently no simple, nondestructive bending (NDB), pre-flexural testing for sorting poles prior to use. In the present paper, the potential for NDB based on bending below the proportional limit was examined to calculate modulus of elasticity (MOE) and thereby predict actual modulus of rupture as determined by destructive bending (MORDB). The investigation was performed on 92 full length 13.3-m long Douglas-fir pole sections. Pre-flexural testing was reasonably correlated with MOEDB, but less well correlated with MORDB. The testing also revealed that visual selection of the best face of a pole, which is used to select a pole oriented to line direction (the “best face”), was poorly correlated with pre-flexing. Increasing the number of NDB tests did not noticeably improve the prediction. The results suggest that pre-flexing might be useful for identifying poles’ performance in service, if more data are available.


ANSI (2015) ANSI 05.1. Wood Poles: Specifications and Dimensions. American National Standards Institute, New York, NY, USA. Search in Google Scholar

ASTM (2015). D 1036 Standard methods for testing wood poles. ASTM Annual Book of Standards, Volume 4.10. West Conshohocken, PA, USA. Search in Google Scholar

Arriaga, F., Íñiguez-González, G., Esteban, M., Divos, F. (2012) Vibration method for grading of large cross-section coniferous timber species. Holzforschung 66:381–387. Search in Google Scholar

Arriaga, F., Monton, J., Segues, E., Íñiguez-Gonzalez, G. (2014) Determination of the mechanical properties of radiata pine timber by means of longitudinal and transverse vibration methods. Holzforschung 68:299–305. Search in Google Scholar

Crews, K., Broughton, G., and Falck, D. (2004). Determination of characteristic stresses and residual life expectancy of preservative treated hardwood and softwood poles. Forest and Wood Products Research and Development Corporation, Victoria, Australia, pp. 54. Search in Google Scholar

Denzler, J., Weidenhiller, A. (2016) Pre-grading of spruce logs containing frozen and unfrozen water by means of frequency-based nondestructive testing (NDT). Holzforschung 70:79–85. Search in Google Scholar

Elkins, L. (2005). Method for testing construction and utility poles. MS thesis. Oregon State University, Corvallis, OR, USA. Search in Google Scholar

Elkins, L., Morrell, J.J., Leichti, R.J. (2007) Establishing a through boring pattern for utility poles. Wood Fiber Sci. 39:639–650. Search in Google Scholar

Goncalves, R., Malgalhaes, G., Herrera, S., Bartholomeu, A. (2006) Using ultrasonic wave propagation to grading new wooden and concrete poles. ECNDT Fr.1.2.4. Search in Google Scholar

Green, D.W., Gorman, T.W., Evans, J.W., Murphy, J. F. (2006). Mechanical grading of round timber beams. J. Mater. Civil Eng. 18:1–10. Search in Google Scholar

Hron, J., Yazdani, J. (2010). Nondestructive strength assessment of in-place wood utility poles. J. Perform. Constr. Fac. 25: 121–129. Search in Google Scholar

Iliadis, L., Mansfield, S.D., Avramidis, S., El-Kassaby, Y.A. (2013) Predicting Douglas-fir wood density by artificial neural networks (ANN) based on progeny testing information. Holzforschung 67:771–777. Search in Google Scholar

McLean, J.P., Evans, R. Moore, J.R. (2010). Predicting the longitudinal modulus of elasticity of Sitka Spruce from cellulose orientation and abundance. Holzforschung 64:492–500. Search in Google Scholar

Morrell, J.J., Love, C.S., Clauson, M. (2011). Effect of through boring, radial drilling and deep incising on flexural properties of Douglas-fir poles. Proc. Am. Wood Protect. Assoc. 107:99–103. Search in Google Scholar

Morrell, J.J., Sinha, A., Clauson, M., Love, C.S. (2014) Effect of inspection holes on flexural properties of Douglas-fir utility poles. Forest Prod. J. 64:300–313. Search in Google Scholar

Oliveira, J.T. da Silva, Wang, X., Vidaurre, G.B. (2017) Assessing specific gravity of young Eucalyptus plantation trees using a resistance drilling technique. Holzforschung 71:137–145. Search in Google Scholar

Ponneth, D., Vasu, A.E., Easwaran, J.C., Mohandass, A. Chauhan, S.S. (2014) Destructive and non-destructive evaluation of seven hardwoods and analysis of data correlation. Holzforschung 68:951–956. Search in Google Scholar

Ross, R.J. (2015) Nondestructive evaluation of wood. General Technical Report FPL-GTR-238, U.S. Forest Products Laboratory, Madison, WI, USA. Search in Google Scholar

Stewart, A.H., Goodman, J.R. (1990) Life cycle economics of wood pole utility structures. IEEE Trans. Power Del. 5: 1040–1046. Search in Google Scholar

Torrán, E. A., Zitto, S., Cotrina, A.D., Piter, J.C. (2009) Bending strength and stiffness of poles of Argentinean Eucalyptus grandis. Madieras Cienc. Tecnol. 11: 71–84. Search in Google Scholar

U.S. Department of Agriculture (USDA) (2010) Wood Handbook: Wood as an Engineering Material. General Technical Report FPL-GTR-190. U.S. Forest Products Laboratory, Madison, WI, USA. Search in Google Scholar

Wang, Y. and Bodig, J. (1990) Strength-grading method for wood poles. J. Struct. Eng. 116:952–967. Search in Google Scholar

Watanabe, U., Fujita, M, Norimoto, M. (2002). Transverse Young’s moduli and cell shapes in coniferous early wood. Holzforschung 56:1–6. Search in Google Scholar

Wolfe, R., Bodig, J., Lebow, P. (2001). Derivation of nominal strength for wood utility poles. General Technical Report FPL-GTR-128. U.S. Forest Products Laboratory, Madison, WI, USA. Search in Google Scholar

Wood, L.W., Erickson, E.C.O., Dohr, A.W. (1960) Strength and related properties of wood poles: final report. American Society for Testing Materials, Philadelphia, PA, p. 194. Search in Google Scholar

Yin, Y., Nagao, H., Liu, X. Nakai, T.Y. (2010) Mechanical properties assessment of Cunninghamia lanceolata plantation wood with three acoustic-based nondestructive methods. J. Inst. Wood Sci. 56:33–40. Search in Google Scholar

Received: 2016-9-19
Accepted: 2017-1-7
Published Online: 2017-2-23
Published in Print: 2017-5-1

©2017 Walter de Gruyter GmbH, Berlin/Boston