Effects of Long-Term Dynamic Loading and Fluctuating Water Table on Helical Anchor Performance for Small Wind Tower Foundations
Publication: Journal of Performance of Constructed Facilities
Volume 23, Issue 4
Abstract
The application of this study is to use helical anchors as a foundation system for small wind tower guyed cables. Helical anchors are currently used to anchor guyed cables of cell or transmission towers. However, the increased dynamic vibrations a wind turbine adds to the tower and foundation system under working loads, as well as extreme environmental conditions (e.g., straight line winds, ice load, or sudden furling shocks), require additional knowledge about the behavior of helical anchors. These field conditions were simulated in this study from tower-instrumented field data on wind speed and tower response. These tower responses were then transmitted to the helical anchors through an extensive, large-scale testing program that included monitoring the performance of the helical anchor foundation under dynamic loads, subject to natural variations in both wind regimes, precipitation (water level) and variations in helical anchor geometry. This paper compares the uplift prediction methods used in helical anchor design as well as discusses the effects of long-term dynamic loading and fluctuating water table on helical anchor performance.
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Acknowledgments
This research project was funded by the Oklahoma Center for the Advancement of Science and Technology (OCAST), Project No. AR062.007, and is a joint venture with Bergey Windpower Company, Inc. The writers are grateful for the time, support, and material donations from Hubbell Power Systems/Chance Civil Construction. We would also like to thank our installers from Atlas Systems of Oklahoma, Sam Lowry and Mike Schweighardt; and Michael Schmitz, Fears Structural Lab Supervisor; and Russell Buhler, Geotechnical Engineering Undergraduate Researcher, for their technical assistance with this project.
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Information & Authors
Information
Published In
Journal of Performance of Constructed Facilities
Volume 23 • Issue 4 • August 2009
Pages: 251 - 261
Copyright
© 2009 ASCE.
History
Received: Jul 8, 2008
Accepted: Dec 10, 2008
Published online: Mar 11, 2009
Published in print: Aug 2009
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