Tightening Procedures for Proper Installation of Anchor Rods in Ancillary Structures
Publication: Journal of Structural Engineering
Volume 147, Issue 10
Abstract
In the last 2 decades, many ancillary structures have collapsed, with several instances traceable to loose anchor nuts. According to a quality assurance inspection conducted by the Virginia Department of Transportation (VDOT) in 2012, approximately 30% of the anchor nuts on the inspected ancillary structures across the state of Virginia were found to be loose. The exact cause of the loose anchor nuts is not known; however, one theory is that specified tightening procedures were not properly followed or were not adequate. Currently, a turn-of-the-nut method is used for the tightening of anchor nuts on double-nut moment connections at the base of ancillary structures. This research reviewed current tightening procedures for anchor nuts on ancillary structures. The relationship between three critical tightening parameters—applied torque, nut rotation, and pretension in the rod—was examined. One hundred galvanized steel anchor rods of five different diameters and three different grades were tested. The experimental tests serve as a benchmark to validate the current tightening procedures, as well as to recommend changes.
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Data Availability Statement
Some or all data, models, or code generated or used during the study are available from the corresponding author by request, including incremental tightening data for nut rotations, measured pretension (strain gauge), and applied torque.
Acknowledgments
The research work reported herein was supported and funded by the Virginia Transportation Research Council (VTRC).
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Published In
Journal of Structural Engineering
Volume 147 • Issue 10 • October 2021
Copyright
© 2021 American Society of Civil Engineers.
History
Received: Sep 30, 2019
Accepted: Apr 19, 2021
Published online: Jul 20, 2021
Published in print: Oct 1, 2021
Discussion open until: Dec 20, 2021
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