Debonding in RC Beams Shear Strengthened with Complete FRP Wraps
Publication: Journal of Composites for Construction
Volume 9, Issue 5
Abstract
Substantial research has been conducted on the shear strengthening of reinforced concrete (RC) beams with bonded fiber reinforced polymer (FRP) strips. The beams may be strengthened in various ways: complete FRP wraps covering the whole cross section (i.e., complete wrapping), FRP U jackets covering the two sides and the tension face (i.e., U jacketing), and FRP strips bonded to the sides only (i.e., side bonding). Shear failure of such strengthened beams is generally in one of two modes: FRP rupture and debonding. The former mode governs in almost all beams with complete FRP wraps and some beams with U jackets, while the latter mode governs in all beams with side strips and U jackets. In RC beams strengthened with complete wraps, referred to as FRP wrapped beams, the shear failure process usually starts with the debonding of FRP from the sides of the beam near the critical shear crack, but ultimate failure is by rupture of the FRP. Most previous research has been concerned with the ultimate failure of FRP wrapped beams when FRP ruptures. However, debonding of FRP from the sides is at least a serviceability limit state and may also be taken as the ultimate limit state. This paper presents an experimental study on this debonding failure state in which a total of 18 beams were tested. The paper focuses on the distribution of strains in the FRP strips intersected by the critical shear crack, and the shear capacity at debonding. A simple model is proposed to predict the contribution of FRP to the shear capacity of the beam at the complete debonding of the critical FRP strip.
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Acknowledgments
The work presented in this paper forms part of the collaborative research between Southeast University, China, The Hong Kong Polytechnic University, China, and the University of Edinburgh, U.K. The writers would like to acknowledge financial support provided by the Foundation for University Key Teacher through the Ministry of Education of China, the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. UNSPECIFIEDPolyU 5151/03E), and the University of Edinburgh, U.K. The first writer would also like to thank the Hwa-Ying Foundation for Education and Culture for sponsoring his visiting scholarship at the University of Edinburgh.
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Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 9 • Issue 5 • October 2005
Pages: 417 - 428
Copyright
© 2005 ASCE.
History
Received: Nov 19, 2004
Accepted: Feb 1, 2005
Published online: Oct 1, 2005
Published in print: Oct 2005
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