Experimental Tests and Design Model for RC Beams Strengthened in Shear Using the Embedded Through-Section FRP Method
Publication: Journal of Composites for Construction
Volume 16, Issue 5
Abstract
This paper presents results of an analytical and experimental investigation on RC T-beams retrofitted in shear with embedded through-section (ETS) fiber-reinforced polymer (FRP). The ETS FRP rod method is a promising method to increase the shear strength of RC beams. As this method develops, the structural behavior of RC beams strengthened with the ETS method needs to be thoroughly characterized and the influencing parameters addressed. In this research study, nine tests were performed on 4,520-mm-long RC T-beams. The parameters of this study are (1) the effect of the surface coating on the FRP bars, (2) the effect of internal transverse steel reinforcement on the FRP shear contribution, (3) the effect of FRP bar spacing, (4) the effect of FRP rod diameter, and (5) the efficiency of the embedded through-section FRP rod method. The main objective of the study is to analyze the behavior of RC T-beams strengthened in shear with ETS FRP rods by varying the parameters just mentioned. New design equations are proposed to calculate the shear contribution of FRP for beams strengthened using the ETS FRP method. The design equations are validated against results collected from the experimental part of the current research study. The proposed model shows an acceptable correlation with the experimental results.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The financial support of the Natural Sciences and Engineering Research Council of Canada (NSERC), the Fonds québécois de la recherche sur la nature et les technologies (FQRNT Research Team Project), and the Ministère des Transports du Québec (MTQ) through operating grants to Amir Mofidi and Profs. Chaallal, Benmokrane, and Neale is gratefully acknowledged. The authors thank Pultrall Inc. (Thetford Mines, Quebec) and Sika Canada Inc. (Pointe Claire, Quebec) for the donation of the CFRP rods. The efficient collaboration of John Lescelleur (senior technician) and Juan Mauricio Rios (technician) at ETS in conducting the tests is acknowledged.
References
American Concrete Institute (ACI). (2007). “State of the art report on FRP for concrete structures.”, Farmington Hills, MI.
American Concrete Institute (ACI). (2008). “Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures.”, Farmington Hills, MI.
Barros, J. A. O., and Dias, S. J. E. (2005). “Near surface mounted CFRP laminates for shear strengthening of concrete beams.” Cem. Concr. Compos., 28(3), 276–292.
Bousselham, A., and Chaallal, O. (2004). “Shear strengthening reinforced concrete beams with fiber-reinforced polymer: Assessment of influencing parameters and required research.” ACI Struct. J., 101(2), 219–227.
Bousselham, A., and Chaallal, O. (2008). “Mechanisms of shear resistance of concrete beams strengthened in shear with externally bonded FRP.” J. Compos. Constr., 12(5), 499–512.
Chaallal, O., Mofidi, A., Benmokrane, B., and Neale, K. (2011). “Embedded through-section FRP rod method for shear strengthening of RC beams: Performance and comparison with existing techniques.” J. Compos. Constr., 15(3), 374–383.
Chaallal, O., Nollet, M. J., and Perraton, D. (1998). “Strengthening of reinforced concrete beams with externally bonded fiber-reinforced-plastic plates: Design guidelines for shear and flexure.” Can. J. Civil Eng., 25(4), 692–704.
Chaallal, O., Shahawy, M., and Hassan, M. (2002). “Performance of reinforced concrete T-girders strengthened in shear with carbon fiber-reinforced polymer fabric.” ACI Struct. J., 99(3), 335–343.
Cosenza, E., Manfredi, G., and Realfonzo, R. (1997). “Behaviour and modeling of bond of FRP rebars to concrete.” J. Compos. Constr., 1(2), 40–51.
Cosenza, E., Manfredi, G., and Realfonzo, R. (2002). “Development length of FRP straight rebars.” Compos. Part B, 33(7), 493–504.
De Lorenzis, L., and Nanni, A. (2001). “Shear strengthening of reinforced concrete beams with near-surface mounted fiber-reinforced polymer rods.” ACI Struct. J., 98(1), 60–68.
Eligehausen, R., Popov, E. P., and Bertero, V. V. (1983). “Local bond stress-slip relationships of deformed bars under generalized excitations.”, Earthquake Engineering Research Center (EERC), Univ. of California, Berkeley, CA.
Khalifa, A., Gold, W. J., Nanni, A., and Aziz, A. (1998). “Contribution of externally bonded FRP to shear capacity of RC flexural members.” J. Compos. Constr., 2(4), 195–203.
Mofidi, A., and Chaallal, O. (2011a). “Shear strengthening of RC beams with EB FRP: Influencing factors and conceptual debonding model.” J. Compos. Constr., 15(1), 62–74.
Mofidi, A., and Chaallal, O. (2011b). “Shear strengthening of RC beams with externally bonded FRP composites: Effect of strip-width-to-strip-spacing ratio.” J. Compos. Constr., 15(5) 732–742.
National Cooperative Highway Research Program (NCHRP). (2008). “Bonded repair and retrofit of concrete structures using FRP composites.”, Washington, DC.
National Cooperative Highway Research Program (NCHRP). (2010). “Recommended guide specification for the design of externally bonded FRP systems for repair and strengthening of concrete bridge elements.”, Washington, DC.
Pecce, M., Manfredi, G., Realfonzo, R., and Cosenza, E. (2001). “Experimental and analytical evaluation of bond properties of GFRP bars.” J. Mater. Civil Eng., 13(4), 280–290.
Rizzo, A., and De Lorenzis, L. (2009). “Behavior and capacity of RC beams strengthened in shear with NSM FRP reinforcement.” Constr. Build. Mater., 23(4), 1555–1567.
Triantafillou, T. C. (1998). “Shear strengthening of reinforced concrete beams using epoxy-bonded FRP composites.” ACI Struct. J., 95(2), 107–115.
Uji, K. (1992). “Improving shear capacity of existing reinforced concrete members by applying carbon fiber sheets.” Trans. Jpn. Concr. Inst., 14, 253–266.
Valerio, P., and Ibell, T. J. (2003). “Shear strengthening of existing concrete bridges.” Proc. Inst. Civil Eng. Struct. Build., 156(1), 75–84.
Valerio, P., Ibell, T. J., and Darby, A. P. (2009). “Deep embedment of FRP for concrete shear strengthening.” Proc. Inst. Civil Eng. Struct. Build., 162(5), 311–321.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 16 • Issue 5 • October 2012
Pages: 540 - 550
Copyright
© 2012 American Society of Civil Engineers.
History
Received: Jun 26, 2011
Accepted: Mar 2, 2012
Published online: Mar 5, 2012
Published in print: Oct 1, 2012
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.