Rectangular Reinforced Concrete Beams Strengthened with CFRP Straps
Publication: Journal of Composites for Construction
Volume 18, Issue 1
Abstract
Shear-deficient reinforced concrete (RC) structures can be effectively strengthened using external prestressed carbon fiber–reinforced polymer (CFRP) straps. Due to the presence of the external elastic straps, a strengthened beam can continue to carry significant load beyond the stages of crack plane slipping and internal-shear stirrup yielding, and the concrete is subjected to high tensile strain levels. As a consequence, the concrete material models play a significant role in the context of modeling such behavior. The modified compression field theory (MCFT), which is a widely accepted shear theory for unstrengthened RC structures, incorporates the details of the stress-strain behavior of concrete. The MCFT also considers compatibility as a governing factor, which facilitates the inclusion of the strap system into the MCFT formulation. In the current study, modifications were investigated to model CFRP strap retrofitted RC beams associated with either uniform or nonuniform strap spacings. An experimental investigation on strengthened and unstrengthened rectangular RC beams was carried out to validate the MCFT predictions for various strap layouts. The validation process revealed that, in general, the MCFT was able to model the shear response of the retrofitted RC beams, but the representation of the softening of the concrete compressive strain, and stress, was found to be influential in the determination of the ultimate load capacity.
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Acknowledgments
The first author is grateful for the financial support provided by the Cambridge Commonwealth Trust, the Overseas Research Studentship, and the Churchill College. The authors are also appreciative of the technical support and assistance provided by EMPA, Dr. N. A. Hoult, Dr. C. T. Morley, Mr. M. R. Touhey, and Mr. S. J. Holder.
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© 2013 American Society of Civil Engineers.
History
Received: Feb 27, 2013
Accepted: Jul 11, 2013
Published online: Jul 13, 2013
Published in print: Feb 1, 2014
Discussion open until: Mar 21, 2014
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