Nondestructive Strength Assessment of In-Place Wood Utility Poles
Publication: Journal of Performance of Constructed Facilities
Volume 25, Issue 2
Abstract
In-place nondestructive simulation evaluation of the remaining bending strength of wooden utility poles is vital to the continued and successful operation of the poles, viability of the electrical transmission and delivery system, and reduction of system disruption potential. A methodology for nondestructively assessing the strength of in-place wood utility poles was developed and is proposed in this paper. Because of the nonhomogeneous and anisotropic nature of wood and the variability of in-place utility poles, a deterministic approach does not seem feasible. The proposed method combines multiple variables to statistically predict the breaking strength, or modulus of rupture, of wood poles. The full-scale testing methodology was tested on real life poles. Results from in-field simulation tests were correlated to data from failure testing of the full-scale poles. The proposed static bending approach is quite accurate, utilizing a device that applies a horizontal force on an in-place utility pole and measures the resulting deflection. The slope of the force-deflection curve and the pole moment of inertia from a regression analysis correlate well to the breaking strength of the poles. Additionally, a method for measuring and adjusting for the tilt of the utility pole under test was determined. Full-scale field simulated testing and break testing data that provide significant insight into nondestructive wood pole testing are provided in this paper. Recommendations for increasing the validity of the proposed model with additional test data, together with implementation of additional relevant parameters, are made.
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Acknowledgments
The study reported in this paper was performed at the request of Oncor Electric Distribution Company headquartered in Dallas. They provided all the funding for this study.
The work was performed by the TCU 2009 Senior Design Team. The project manager of this team was Joel Hron. The members of the team were as follows: Emily Ajubita, Ali Buron, Lauren DelGallego, Gregory Frenzel, Mark Friday, Juan Galicia, Michael Garcia, Gabrielle Greer, Sean Haight, Tommy Hale, Brody Hanson, Jeremy Jenkins, Michael Mangum, Spencer Manning, Dan Miles, Erick Moen, Thuc-Uyen Nguyen, Kyle Nobile, Mitch Owens, Matthew Riley, Armando Rodriguez, Dipil Shrestha, Eric Spaeth, Akhil Thomas, Kevin Tully, Kunal Verma, and Wes Weissgarber. The team was supervised by Dr. Stephen Weis and Dr. Patrick Walter.
References
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Green, D. W., Gorman, T. M., Evans, J. W., and Murphy, J. F. (2006). “Mechanical grading of round timber beams.” J. Mater. Civ. Eng., 18, 1–9.
National Electric Energy Testing Research and Applications Center (NEETRAC). (2008). “Wood pole assessment methods performance characterization.” Research Rep., Georgia Institute of Technology, Atlanta, GA.
Wang, Y., and Bodig, J. (1990). “Strength-grading method for wood poles.” J. Struct. Eng., 116(11), 2952–2967.
Wolfe, R. W., Bodig, J., and Lebow, P. (2001). “Derivation of nominal strength for wood utility poles.” Gen. Tech. Rep. FPL-GTR-128, USDA Forest Products Laboratory.
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© 2011 American Society of Civil Engineers.
History
Received: Aug 14, 2009
Accepted: Feb 25, 2010
Published online: Mar 12, 2010
Published in print: Apr 1, 2011
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