Experimental and Analytical Study of Bond Stress–Slip Behavior at the CFRP-to-Concrete Interface
Publication: Journal of Composites for Construction
Volume 27, Issue 2
Abstract
The application of externally bonded (EB) carbon fiber reinforced polymer (CFRP) systems for strengthening existing structures, such as RC beams, has been widely approved in the construction industry worldwide for its numerous benefits. The CFRP-to-concrete bond has a governing role in the reliability and effectiveness of EB-CFRP systems. Indeed, failure of the CFRP-to-concrete bond can lead to rupture of CFRP-strengthened structures. Hence, ongoing research into assessment of bond behavior at the CFRP-to-concrete interface helps to bring more insightful clarity to the use of EB-CFRP strengthening techniques. The aim of this study is to evaluate the bond behavior between CFRP and concrete by conducting a series of pullout tests. The parameters considered include CFRP type (sheet versus laminate), bonded length, and bonded CFRP width. The results show that using CFRP fabric sheets can contribute to higher bond load-carrying capacity and ductility than CFRP laminates. Furthermore, through the analyses of databases in the literature, a bilinear bond–slip model is proposed that takes into account the CFRP width factor. Through a comparison, it is shown that the proposed model performs well in terms of predicting the maximum local bond stress and CFRP slippage.
Practical Applications
This research was aimed at investigating the use of CFRP composites for strengthening RC structures. The complexities regarding the behavior of CFRP-strengthened RC beams and columns, especially at the CFRP-to-concrete bond, provoked the authors to conduct this experimental study. The testing program was intended to evaluate the effect of certain parameters on the bond behavior of a CFRP-to-concrete interface. In addition, an analytical study was carried out to develop a model, capable of characterizing the interfacial behavior in terms of bond shear stress and bond slip. The proposed model proved to perform well at predicting the bond–slip behavior in a validation study. Findings obtained from this research can better familiarize civil engineers with the application of EB-CFRP strengthening techniques in concrete surfaces and possibly enhance the design of such retrofitting systems in deficient real-life RC structures.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
Financial support of the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Fonds de Recherche du Québec—Nature et Technologie (FRQNT) through operating grants is gratefully acknowledged. The authors thank Sika-Canada, Inc. (Pointe-Claire, Quebec) for contributing to the cost of materials. The efficient collaboration of J. Auger and J. Lescelleur (senior technicians) at École de technologie supérieure in conducting the tests is also acknowledged.
Notation
The following symbols are used in this paper:
- bc
- concrete width;
- bf
- FRP width;
- Ec
- concrete elastic modulus;
- Ef
- FRP elastic modulus;
- Fmax
- maximum double-lap load;
- concrete compressive strength;
- ff
- FRP tensile strength;
- ft
- concrete tensile strength;
- kb
- FRP-to-concrete width factor;
- Lb
- bond length;
- le
- effective bond length;
- nf
- number of FRP layers;
- Pu
- applied pullout load;
- Pult
- ultimate pullout load;
- sf
- total slippage of bonded FRP;
- speak
- bond slip at the maximum bond shear stress;
- sult
- ultimate bond slip;
- tf
- FRP thickness;
- ɛf
- FRP tensile elongation;
- ɛ0
- strain at the free end of FRP;
- τf,ave
- average global bond stress; and
- τmax
- maximum bond stress.
References
Abdalla, J. A., A. Mirghani, and R. A. Hawileh. 2020. “Bond stress and behavior of interface between untreated aluminum alloy surface and concrete.” Procedia Struct. Integrity 28: 1295–1302. https://doi.org/10.1016/j.prostr.2020.11.111.
ACI (American Concrete Institute). 2017. Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures. ACI 440.2R. Farmington Hills, MI: ACI.
ACI (American Concrete Institute). 2019. Building code requirements for structural concrete (ACI 318-19): An ACI standard; commentary on building code requirements for structural concrete (ACI 318-19). ACI 318R. Farmington Hills, MI: ACI.
Aidoo, J., K. A. Harries, and M. F. Petrou. 2004. “Fatigue behavior of carbon fiber reinforced polymer-strengthened reinforced concrete bridge girders.” J. Compos. Constr. 8 (6): 501–509. https://doi.org/10.1061/(ASCE)1090-0268(2004)8:6(501).
Al-Saawani, M. A., A. I. Al-Negheimish, A. K. El-Sayed, and A. M. Alhozaimy. 2022. “Finite element modeling of debonding failures in FRP-strengthened concrete beams using cohesive zone model.” Polymers 14 (9): 1889. https://doi.org/10.3390/polym14091889.
ASTM. 2008. Standard test method for tensile properties of polymer matrix composite materials. ASTM D3039/D3039M-08. West Conshohocken, PA: ASTM.
ASTM. 2021. Standard test method for compressive strength of cylindrical concrete specimens. ASTM C39/C39M-21. West Conshohocken, PA: ASTM.
Brosens, K., and D. Van Gemert. 1999. “Anchorage design for externally bonded carbon fiber reinforced polymer laminates.” Spec. Publ. 188: 635–646.
Chen, J. F., and J. Teng. 2001. “Anchorage strength models for FRP and steel plates bonded to concrete.” J. Struct. Eng. 127 (7): 784–791. https://doi.org/10.1061/(ASCE)0733-9445(2001)127:7(784).
CSA (Canadian Standard Association). 2012. Design and construction of building structures with fibre-reinforced polymers. CSA S806-12. Rexdale, ON, Canada: CSA.
Dai, J., Y. Saito, T. Ueda, and Y. Sato. 2005a. “Static and fatigue bond characteristics of interfaces between CFRP sheets and frost damage experienced concrete.” Spec. Publ. 230: 1515–1530.
Dai, J., T. Ueda, and Y. Sato. 2005b. “Development of the nonlinear bond stress–slip model of fiber reinforced plastics sheet–concrete interfaces with a simple method.” J. Compos. Constr. 9 (1): 52–62. https://doi.org/10.1061/(ASCE)1090-0268(2005)9:1(52).
Daud, R. A., L. S. Cunningham, and Y. C. Wang. 2015. “Static and fatigue behaviour of the bond interface between concrete and externally bonded CFRP in single shear.” Eng. Struct. 97: 54–67. https://doi.org/10.1016/j.engstruct.2015.03.068.
De Lorenzis, L., B. Miller, and A. Nanni. 2001. “Bond of FRP laminates to concrete.” ACI Mater. J. 98 (3): 256–264.
De Maio, U., F. Greco, L. Leonetti, P. N. Blasi, and A. Pranno. 2022. “An investigation about debonding mechanisms in FRP-strengthened RC structural elements by using a cohesive/volumetric modeling technique.” Theor. Appl. Fract. Mech. 117: 103199. https://doi.org/10.1016/j.tafmec.2021.103199.
Fathi, A., G. El-Saikaly, and O. Chaallal. 2022. “On bond–slip of EB-FRP/concrete interface in shear under fatigue loading: Review and synthesis of experimental studies and models.” J. Civ. Eng. Constr. 11 (1): 1–19. https://doi.org/10.32732/jcec.2022.11.1.1.
Ferrier, E., M. Quiertant, K. Benzarti, and P. Hamelin. 2010. “Influence of the properties of externally bonded CFRP on the shear behavior of concrete/composite adhesive joints.” Composites, Part B 41 (5): 354–362. https://doi.org/10.1016/j.compositesb.2010.03.007.
fib (International Federation for Structural Concrete). 2019. Externally applied FRP reinforcement for concrete structures. Bulletin 90. fib TG5.1. Lausanne, Switzerland: fib.
Godat, A., R. Prowt, and O. Chaallal. 2016. “Bond mechanism of a new anchorage technique for FRP shear-strengthened T-beams using CFRP rope.” J. Reinf. Plast. Compos. 35 (6): 487–503. https://doi.org/10.1177/0731684415617840.
JCI (Japan Concrete Institute). 2003. “Technical report of technical committee on retrofit technology.” In Proc., Int. Symp. on the Latest Achievement of Technology and Research on Retrofitting Concrete Structures. Tokyo: Japan Concrete Institute.
Khalifa, A., W. J. Gold, A. Nanni, and A. A. MI. 1998. “Contribution of externally bonded FRP to shear capacity of RC flexural members.” J. Compos. Constr. 2 (4): 195–202. https://doi.org/10.1061/(ASCE)1090-0268(1998)2:4(195).
Kim, Y. J., and P. J. Heffernan. 2008. “Fatigue behavior of externally strengthened concrete beams with fiber-reinforced polymers: State of the art.” J. Compos. Constr. 12 (3): 246–256. https://doi.org/10.1061/(ASCE)1090-0268(2008)12:3(246).
Lin, J.-P., Y.-F. Wu, and S. T. Smith. 2017. “Width factor for externally bonded FRP-to-concrete joints.” Constr. Build. Mater. 155: 818–829. https://doi.org/10.1016/j.conbuildmat.2017.08.104.
Lu, X., J. Teng, L. Ye, and J. Jiang. 2005. “Bond–slip models for FRP sheets/plates bonded to concrete.” Eng. Struct. 27 (6): 920–937. https://doi.org/10.1016/j.engstruct.2005.01.014.
Maeda, T., Y. Asano, Y. Sato, T. Ueda, and Y. Kakuta. 1997. “A study on bond mechanism of carbon fiber sheet.” In Proc., 3rd Int. Symp. of Non-Metallic (FRP) Reinforcement for Concrete Structures, 279–286. Sapporo, Japan: Japan Concrete Institute.
Mazzotti, C., M. Savoia, and B. Ferracuti. 2008. “An experimental study on delamination of FRP plates bonded to concrete.” Constr. Build. Mater. 22 (7): 1409–1421. https://doi.org/10.1016/j.conbuildmat.2007.04.009.
McSweeney, B., and M. Lopez. 2005. “FRP-concrete bond behavior: A parametric study through pull-off testing.” Spec. Publ. 230: 441–460.
Mohammadi, T., and B. Wan. 2015. “Sensitivity analysis of stress state and bond strength of fiber-reinforced polymer/concrete interface to boundary conditions in single shear pull-out test.” Adv. Mech. Eng. 7 (5): 1687814015585419. https://doi.org/10.1177/1687814015585419.
Monti, G., M. Renzelli, and P. Luciani. 2003. “FRP adhesion in uncracked and cracked concrete zones.” In Vol. 2 of Fibre-Reinforced Polymer Reinforcement for Concrete Structures, edited by K. H. Tan, 183–192. Singapore: World Scientific.
Nakaba, K., T. Kanakubo, T. Furuta, and H. Yoshizawa. 2001. “Bond behavior between fiber-reinforced polymer laminates and concrete.” Struct. J. 98 (3): 359–367.
Neubauer, U., and F. Rostasy. 1999. “Bond failure of concrete fiber reinforced polymer plates at inclined cracks—Experiments and fracture mechanics model.” Spec. Publ. 188: 369–382.
Niedermeier, R. 1996. “Stellungnahme zur richtlinie für das verkleben von betonbauteilen durch ankleben von stahllaschen—Entwurf März 1996.” [In German] In Schreiben 1390 vom 30.10.1996 des Lehrstuhls für Massivbau. Munich, Germany: Technische Univ. München.
Oudah, F., and R. El-Hacha. 2013. “Research progress on the fatigue performance of RC beams strengthened in flexure using fiber reinforced polymers.” Composites, Part B 47: 82–95. https://doi.org/10.1016/j.compositesb.2012.09.057.
Ben Ouezdou, M., A. Belarbi, and S.-W. Bae. 2009. “Effective bond length of FRP sheets externally bonded to concrete.” Int. J. Concr. Struct. Mater. 3 (2): 127–131. https://doi.org/10.4334/IJCSM.2009.3.2.127.
Pellegrino, C., D. Tinazzi, and C. Modena. 2008. “Experimental study on bond behavior between concrete and FRP reinforcement.” J. Compos. Constr. 12 (2): 180–189. https://doi.org/10.1061/(ASCE)1090-0268(2008)12:2(180).
Rabinovitch, O. 2014. “An extended high order cohesive interface approach to the debonding analysis of FRP strengthened beams.” Int. J. Mech. Sci. 81: 1–16. https://doi.org/10.1016/j.ijmecsci.2014.01.013.
Savoia, M., B. Ferracuti, and C. Mazzotti. 2003. “Non linear bond–slip law for FRP-concrete interface.” In Vol. 2 of Fibre-Reinforced Polymer Reinforcement for Concrete Structures, edited by K. H. Tan,163–172. Singapore: World Scientific.
Sika Canada. 2022a. “Sika® CarboDur® S Carbon fibre laminate for structural strengthening.” Version 05.01. Sika Group. https://can.sika.com/content/dam/dms/ca01/6/sika-carbodur-s.pdf.
Sika Canada. 2022b. “SikaWrap® Hex-103 C Carbon fibre fabric for structural strengthening.” Version 01.01. Sika Group. https://can.sika.com/content/dam/dms/ca01/5/sikawrap-hex-103c.pdf.
Sun, W., X. Peng, H. Liu, and H. Qi. 2017a. “Numerical studies on the entire debonding propagation process of FRP strips externally bonded to the concrete substrate.” Constr. Build. Mater. 149: 218–235. https://doi.org/10.1016/j.conbuildmat.2017.05.117.
Sun, W., X. Peng, and Y. Yu. 2017b. “Development of a simplified bond model used for simulating FRP strips bonded to concrete.” Compos. Struct. 171: 462–472. https://doi.org/10.1016/j.compstruct.2017.03.066.
Ueda, T., Y. Sato, and Y. Asano. 1999. “Experimental study on bond strength of continuous carbon fiber sheet.” Spec. Publ. 188: 407–416.
Wang, X., M. Sayed Ahmed, and Z. Wu. 2014. “Modeling of the flexural fatigue capacity of RC beams strengthened with FRP sheets based on finite-element simulation.” J. Struct. Eng. 141 (8): 04014189. https://doi.org/10.1061/(ASCE)ST.1943-541X.0001161.
Wu, Z., S. Islam, and H. Said. 2009. “A three-parameter bond strength model for FRP—Concrete interface.” J. Reinf. Plast. Compos. 28 (19): 2309–2323. https://doi.org/10.1177/0731684408091961.
Yang, Y., Q. Yue, and Y. Hu. 2001. “Experimental study on bond performance between carbon fiber sheets and concrete.” J. Build. Struct. 3: 36–41.
Yao, J., J. Teng, and J. F. Chen. 2005. “Experimental study on FRP-to-concrete bonded joints.” Composites, Part B 36 (2): 99–113. https://doi.org/10.1016/j.compositesb.2004.06.001.
Yuan, C., W. Chen, T. M. Pham, and H. Hao. 2019. “Bond behaviour between hybrid fiber reinforced polymer sheets and concrete.” Constr. Build. Mater. 210: 93–110. https://doi.org/10.1016/j.conbuildmat.2019.03.082.
Yuan, H., J. Teng, R. Seracino, Z. Wu, and J. Yao. 2004. “Full-range behavior of FRP-to-concrete bonded joints.” Eng. Struct. 26 (5): 553–565. https://doi.org/10.1016/j.engstruct.2003.11.006.
Zhang, P., Y. Hu, Y. Pang, H. Feng, D. Gao, J. Zhao, and S. A. Sheikh. 2020. “Influence factors analysis of the interfacial bond behavior between GFRP plates, concrete.” Structures 26: 79–91.
Zhang, W. 2018. “Prediction of the bond–slip law between externally bonded concrete substrates and CFRP plates under fatigue loading.” Int. J. Civ. Eng. 16 (9): 1085–1096. https://doi.org/10.1007/s40999-017-0258-8.
Zhou, H., D. Fernando, and J.-G. Dai. 2021. “The bond behaviour of CFRP-to-concrete bonded joints under fatigue cyclic loading: An experimental study.” Constr. Build. Mater. 273: 121674. https://doi.org/10.1016/j.conbuildmat.2020.121674.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 27 • Issue 2 • April 2023
Copyright
© 2023 American Society of Civil Engineers.
History
Received: Jul 9, 2022
Accepted: Oct 30, 2022
Published online: Jan 24, 2023
Published in print: Apr 1, 2023
Discussion open until: Jun 24, 2023
ASCE Technical Topics:
- Beams
- Bonding
- Carbon fibers
- Concrete beams
- Engineering materials (by type)
- Fiber reinforced polymer
- Fibers
- Geomechanics
- Geotechnical engineering
- Materials engineering
- Materials processing
- Polymer
- Pullout behavior
- Soil dynamics
- Soil mechanics
- Structural behavior
- Structural engineering
- Structural members
- Structural strength
- Structural systems
- Synthetic materials
- Uplifting behavior
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.
Cited by
- Abbas Fathi, Georges El-Saikaly, Omar Chaallal, Fatigue Behavior in the Carbon-Fiber-Reinforced Polymer-to-Concrete Bond by Cyclic Pull-Out Test: Experimental and Analytical Study, Journal of Composites for Construction, 10.1061/JCCOF2.CCENG-4222, 27, 4, (2023).