Predicting Residual Tensile Strength of Seven-Wire Strands Using That of Single Wires Exposed to Chloride Environments
Publication: Journal of Materials in Civil Engineering
Volume 26, Issue 8
Abstract
The steel strands in posttensioned (PT) concrete systems are typically embedded inside cementitious grout for protection from the environment. However, strands not embedded in grout have been observed in PT systems. The exposed strand is susceptible to corrosion, and particularly the location where the strand protrudes from the grout (i.e., grout-air-steel interface) is more vulnerable to corrosion. Prediction of the tension capacity () of strands with such interfaces under various exposure conditions is necessary for structural assessment. This prediction could be accomplished by using the data from an experimental program that includes the exposure of strands to various corrosive environments and testing to determine the time-variant residual of these strands. However, these tests are cumbersome and expensive, especially when it is necessary to maintain very high tensile stress conditions during the exposure period to simulate the in-service stress conditions on the strands in PT systems. Similar investigations of unstressed single wires are simpler and less expensive. This paper presents an experimental investigation of the corrosion-induced losses in the of unstressed wires, unstressed strands, and stressed strands. Based on these data, this paper develops probabilistic models to predict the of unstressed wires with grout-air-steel interfaces and subjected to various moisture and chloride conditions. By using these models for wires and the experimental data on strands, two probabilistic models are then developed to predict the of stressed strands based on the of unstressed wires. The developed models can be used to determine the of strands with grout-air-steel interfaces subjected to various exposure conditions, provided the of corresponding wires under those conditions is estimated.
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Acknowledgments
This research was performed at Texas Transportation Institute and Zachry Department of Civil Engineering, Texas A&M University, College Station, Texas, through the sponsored project No. 0-4588 (2003-2008) from the Texas Department of Transportation (TxDOT), Austin, Texas. The authors also acknowledge the assistance from Mr. Jeff Perry, Mr. Matt Potter, Mr. Scott Crauneur, Mr. Scott Dobrovolny, Mr. Robert Kocman, Mr. Ramesh Kumar, and Prof. Daren Cline.
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Published In
Journal of Materials in Civil Engineering
Volume 26 • Issue 8 • August 2014
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Mar 3, 2013
Accepted: Aug 30, 2013
Published online: Sep 2, 2013
Published in print: Aug 1, 2014
Discussion open until: Oct 9, 2014
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