Bond Strength Model for CFRP Strips Near-Surface Mounted to Concrete
Publication: Journal of Composites for Construction
Volume 18, Issue 3
Abstract
This paper is concerned with the development of an accurate bond strength model for carbon-fiber-reinforced polymer (CFRP) strips near-surface mounted (NSM) to concrete where debonding occurs as a result of cohesion failure in the adjacent concrete. Based on an existing analytical solution and the fracture energy equation recently developed by the authors, a bond strength equation is first proposed for NSM CFRP strip-to-concrete bonded joints with a sufficient bond length (i.e., the bond length exceeds a threshold value referred to as the effective bond length). The influence of an insufficient bond length on the bond strength is next examined through a parametric study conducted using a beam-spring numerical model in which a bond-slip model recently proposed by the authors is incorporated. Based on the numerical results, expressions are formulated for the effective bond length and the bond-strength reduction factor for insufficient bond lengths. The combination of these equations leads to a new bond strength model for NSM CFRP strip-to-concrete bonded joints. The predictions of the proposed bond strength model are compared with the results of 51 test specimens collected from seven existing studies and the predictions of the only existing bond strength model for such joints. These comparisons indicate that the proposed model is accurate and superior to the existing bond strength model, particularly for joints with insufficient bond lengths. The proposed bond strength model, because of its accuracy and simplicity, can be readily incorporated in design codes and guidelines.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors are grateful for the financial support received from the National Basic Research Program of China (“973” Program) (Project No. 2012CB026201) and for the Niche Area Funding Scheme of Hong Kong Polytechnic University.
References
Blaschko, M. (2003). “Bond behaviour of CFRP strips glued into slits.” Proc., 6th Int. Symp. on Fibre-Reinforced Polymer (FRP) Reinforcement for Concrete Structures, World Scientific, Singapore, 205–214.
Chen, J. F., and Teng, J. G. (2001). “Anchorage strength models for FRP and steel plates bonded to concrete.” J. Struct. Eng., 784–791.
De Lorenzis, L., and Teng, J. G. (2007). “Near-surface mounted FRP reinforcement: An emerging technique for strengthening structures.” Compos. B Eng., 38(2), 119–143.
De Lorenzis, L., and Zavarise, G. (2009). “Cohesive zone modelling of interfacial stresses in plated beams.” Int. J. Solids Struct., 46(24), 4181–4191.
El Hacha, R., and Rizkalla, S. H. (2004). “Near-surface-mounted fiber-reinforced polymer reinforcements for flexural strengthening of concrete structures.” ACI Struct. J., 101(5), 717–726.
Li, R., Teng, J. G., and Yue, Q. R. (2005). “Experimental study on bond behavior of NSM CFRP strips-concrete interface.” Ind. Constr., 35(8), 31–35 (in Chinese).
Lu, X. Z., Teng, J. G., Ye, L. P., and Jiang, J. J. (2005). “Bond-slip models for FRP sheets/plates bonded to concrete.” Eng. Struct., 27(6), 920–937.
Oehlers, D. J., Haskett, M., Wu, C. Q., and Seracino, R. (2008). “Embedding NSM FRP plates for improved IC debonding resistance.” J. Compos. Constr., 635–642.
Perera, W. K. K. G., Ibell, T. J., and Darby, A. P. (2009). “Bond behaviour and effectiveness of various shapes of NSM CFRP bars.” Proc., 9th Int. Symp. on Fiber-Reinforced Polymers Reinforcement for Concrete Structures (FRPRCS-9) (CD-ROM), Univ. of Adelaide, Adelaide.
Rashid, R., Oehlers, D. J., and Seracino, R. (2008). “IC debonding of FRP NSM and EB retrofitted concrete: Plate and cover interaction tests.” J. Compos. Constr., 160–167.
Sena Cruz, J. M., and Barros, J. A. O. (2002). “Bond behavior of carbon laminate strips into concrete by pull-out bending tests.” Proc., 3rd Int. Symp. on Bond in Concrete–From Research to Standards, Budapest University of Technology and Economics, Budapest, Hungary, 614–621.
Sena Cruz, J. M., and Barros, J. A. O. (2004). “Bond between near-surface mounted carbon-fiber-reinforced polymer laminate strips and concrete.” J. Compos. Constr., 519–527.
Seracino, R., Jones, N. M., Ali, M. S. M., Page, M. W., and Oehlers, D. J. (2007a). “Bond strength of near-surface mounted FRP strip-to-concrete joints.” J. Compos. Constr., 401–409.
Seracino, R., Saifulnaz, M. R. R., and Oehlers, D. J. (2007b). “Generic debonding resistance of EB and NSM plate-to-concrete joints.” J. Compos. Constr., 62–70.
Shield, C. K., French, C. W., and Milde, E. (2005). “The effect of adhesive type on the bond of NSM tape to concrete.” ACI SP230: 7th Int. Symp. on Fiber-Reinforced Polymer (FRP) Reinforcement for Concrete Structures, American Concrete Institute, Detroit, MI, 355–372.
Taljsten, B. (1994). “Plate bonding: Strengthening of existing concrete structures with epoxy bonded plates of steel or fibre reinforced plastics.” Ph.D. thesis, Lulea Univ. of Technology, Lulea, Sweden.
Teng, J. G., Chen, J. F., Smith, S. T., and Lam, L. (2002). FRP-strengthened RC structures, Wiley, Chichester, U.K.
Teng, J. G., Zhang, S. S., Dai, J. G., and Chen, J. F. (2013). “Three-dimensional meso-scale finite element modeling of bonded joints between a near-surface mounted FRP strip and concrete.” Comput. Struct., 117, 105–117.
Thorenfeldt, E. (2007). “Bond capacity of CFRP strips glued to concrete in sawn slits.” Proc., 8th Int. Conf. on Fibre Reinforced Plastics for Reinforced Concrete Structures (CD-ROM), Univ. of Patras, Patras, Greece.
Triantafillou, T. C., and Plevris, N. (1992). “Strengthening of RC beams with epoxy-bonded fiber-composite materials.” Mater. Struct., 25(148), 201–211.
Yao, J., Teng, J. G., and Chen, J. F. (2005). “Experimental study on FRP-to-concrete bonded joints.” Compos. B Eng., 36(2), 99–113.
Yuan, H., Teng, J. G., Seracino, R., Wu, Z. S., and Yao, J. (2004). “Full-range behavior of FRP-to-concrete bonded joints.” Eng. Struct., 26(5), 553–565.
Yuan, H., Wu, Z. S., and Yoshizawa, H. (2001). “Theoretical solutions on interfacial stress transfer of externally bonded steel/composite laminates.” J. Struct. Mech. Earthquake Eng., 18(1), 27–39.
Zhang, S. S. (2012). “Behaviour and modelling of RC beams strengthened in flexure with near-surface mounted FRP strips.” Ph.D. thesis, Hong Kong Polytechnic Univ., Hong Kong.
Zhang, S. S., and Teng, J. G. (2010). “Finite element prediction of plate-end cover separation in FRP-strengthened RC beams.” Proc., 11th Int. Symp. on Structural Engineering, Science Press, Beijing, China, 1794–1799.
Zhang, S. S., Teng, J. G., and Yu, T. (2013). “Bond-slip model for CFRP strips near-surface mounted to concrete.” Eng. Struct., 56, 945–953.
Information & Authors
Information
Published In
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Jan 15, 2013
Accepted: Jun 6, 2013
Published online: Jun 8, 2013
Published in print: Jun 1, 2014
Discussion open until: Jul 18, 2014
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.