Conceptual Model for Prediction of FRP-Concrete Bond Strength under Moisture Cycles
Publication: Journal of Composites for Construction
Volume 15, Issue 5
Abstract
Fiber-reinforced polymer (FRP) retrofit systems for concrete structural members such as beams, columns, slabs, and bridge decks have become increasingly popular as a result of extensive studies on short-term debonding behavior. Nevertheless, long-term performance and durability issues regarding debonding behavior in such strengthening systems still remain largely uncertain and unanswered. Because of its composite nature, the effectiveness of the strengthening system depends on the properties of the interfaces between the three constituent materials; namely, concrete, epoxy, and FRP. Certain factors, including those related to environmental exposures, can cause degradation of the interface properties during service life. This is particularly critical when predicting service life and planning maintenance of FRP-strengthened concrete structures. In this study, effect of moisture on an FRP-concrete bond system is characterized by means of the tri-layer fracture toughness, which can be obtained experimentally from peel and shear fracture tests. Fracture specimens were conditioned under various durations and numbers of wet-dry cycles at room temperature and 50°C. An irreversible weakening in bond strength was observed in fracture specimens under moisture cyclic condition. A conceptual model is developed based on the experimental results of the fracture specimens under variable cyclic moisture conditions for the bond strength prediction of the FRP-concrete bond system. A numerical study of a precracked FRP-strengthened reinforced concrete beam is then performed to show potential application of the proposed predictive model.
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Acknowledgments
This research was supported by the National Science Foundation (NSF) CMS Grant No. NSF0510797. The authors are grateful to the former program manger, Dr. Lawrence C. Bank, for his interest and support of this work.
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Published In
Journal of Composites for Construction
Volume 15 • Issue 5 • October 2011
Pages: 743 - 756
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Jul 30, 2010
Accepted: Feb 9, 2011
Published online: Feb 11, 2011
Published in print: Oct 1, 2011
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