Fatigue Performance of RC Beams Strengthened in Shear with CFRP Fabrics
Publication: Journal of Composites for Construction
Volume 14, Issue 4
Abstract
In recent years, a tremendous effort has been directed toward understanding and promoting the use of externally bonded fiber-reinforced polymer (FRP) composites to strengthen concrete structures. Despite this research effort, studies on the behavior of beams strengthened with FRP under fatigue loading are relatively few, especially with regard to its shear-strengthening aspect. This study aims to examine the fatigue performance of RC beams strengthened in shear using carbon FRP (CFRP) sheets. It involves six laboratory tests performed on full-size T-beams, where the following parameters are investigated: (1) the FRP ratio and (2) the internal transverse-steel reinforcement ratio. The major finding of this study is that specimens strengthened with one layer of CFRP survived 5 million cycles, some of them with no apparent signs of damage, demonstrating thereby the effectiveness of FRP strengthening systems on extending the fatigue life of structures. Specimens strengthened with two layers of CFRP failed in fatigue well below 5 million cycles. The failure mode observed for these specimens was a combination of crushing of the concrete struts, local debonding of CFRP, and yielding of steel stirrups. This failure may be attributed to the higher load amplitude and also to the greater stiffness of the FRP which may have changed the stress distribution among the different components coming into play. Finally, comparison between the performance of specimens with transverse steel and without seems to indicate that the addition of transverse steel extends the fatigue life of RC beams.
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Acknowledgments
The financial support of the National Science and Engineering Research Council of Canada (NSERC) and the Fonds québécois de la recherche sur la nature et les technologies (FQRNT) through operating grants is gratefully acknowledged. In addition, the writers wish to thank John Lescelleur, senior technician at ETS, for his efficient collaboration in conducting the tests.
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Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 14 • Issue 4 • August 2010
Pages: 415 - 423
Copyright
© 2010 ASCE.
History
Received: Mar 9, 2009
Accepted: Dec 3, 2009
Published online: Feb 6, 2010
Published in print: Aug 2010
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