Behavior of RC T-Beams Strengthened in Shear with CFRP under Cyclic Loading
Publication: Journal of Bridge Engineering
Volume 18, Issue 2
Abstract
This study investigated the shear performance of an RC beam strengthened in shear with externally bonded carbon fiber-reinforced polymer (CFRP) strips, subjected to a cyclic loading for 2 million cycles at 1 Hz. The stress level in the stirrups caused by the cyclic loading used in this study was higher than those typically used in fatigue studies, which could have caused the yielding of some stirrups from the beginning of cyclic loading. This was done to reflect the fact that many RC beams in need of shear strengthening do not meet the minimum stirrup requirement for the new and increased shear demand. The experimental results obtained in this study and a comprehensive review of the existing literature showed that RC beams strengthened in shear with externally bonded CFRP could survive 2 million cycles of cyclic loading without failure. Furthermore, the residual shear strength of the FRP-strengthened beam appeared to be greater, albeit slightly, than the static shear strength of the unstrengthened control beam. This study’s results also suggested that limiting the interfacial stress in CFRP strips to less than 1.5 MPa or 25% of its ultimate interfacial strength would increase fatigue life by avoiding debonding of CFRP strips.
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Acknowledgments
This research was sponsored by the American Association of State Highway and Transportation Officials, in cooperation with the Federal Highway Administration, and was conducted as part of the National Cooperative Highway Research Program Project 12-75, administered by the Transportation Research Board of the National Research Council, with Amir Hanna as the Project Manager. Assistance from the High-Bay Structures Laboratory at Missouri University of Science and Technology is greatly acknowledged, as is the help from Egyptian Concrete, Inc., Ashraf Ayoub (University of Houston), Ayman Okeil (Louisiana State University), Daniel Kuchma (University of Illinois at Urbana-Champaign), and graduate students who worked on this project, including Youngmin You, Carlos Ortega, Antonio Brancaccio, and Rocio Tumialan. The authors also thank the reviewers for valuable comments and guidance to make this paper more valuable. Findings and opinions expressed here, however, are those of the authors alone and not necessarily the views of the sponsoring agencies.
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Information & Authors
Information
Published In
Journal of Bridge Engineering
Volume 18 • Issue 2 • February 2013
Pages: 99 - 109
Copyright
© 2013 American Society of Civil Engineers.
History
Received: Mar 25, 2011
Accepted: Oct 25, 2011
Published online: Oct 27, 2011
Published in print: Feb 1, 2013
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