Bond of NSM FRP-Strengthened Concrete: Round Robin Test Initiative
Publication: Journal of Composites for Construction
Volume 20, Issue 1
Abstract
Despite the extensive research on the debonding behavior of fiber-reinforced polymer (FRP) strengthening systems, no standard methodology has been established on its experimental characterization. To assess the performance and reliability of small-scale testing on near-surface mounted (NSM) FRP strengthening systems, an experimental program was carried out on a series of nine NSM FRP strengthening systems (bars and strips), in the framework of an international round robin testing (RRT). Eleven laboratories and seven manufacturers and suppliers participated in this extensive international exercise, which regarded both NSM and EBR FRP strengthening systems. The experimental results are discussed and compared in this paper in order to investigate (1) the bond behavior of NSM strips and bars, (2) the influence of alternative single-bond or double-bond shear pulling setups adopted by the participating laboratories, and (3) the influence in concrete strength due to different constituent materials between countries in applying a prescribed mix. The results show no significant influence of the concrete strength on both failure modes and loads. On the other hand, axial stiffness and surface treatment of the FRP NSM systems strongly affect both the bond strength and the parameters identifying the bond laws. Differences of bond strength experimentally recorded for the same FRP NSM systems tested according to different setups range between 10 and 25%. Therefore, for standard bond test protocol, the single shear bond test setup is more reliable, due to its higher feasibility compared with the double shear test setup.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors wish to acknowledge the financial assistance of the European Union for the Marie Curie Research Training Network En-Core, and the support of TG 9.3 of the International Federation for Structural Concrete (fib). Hughes Brothers and Fortius, Magmatech, Schock, S&P, Sika, ATP, and Sto Scandinavia AB are acknowledged for their participation in the RRT and for supplying the test materials.
References
ACI (American Concrete Institute). (2008). “Guide test methods for fiber-reinforced polymers (FRPs) for reinforcing or strengthening concrete structures.”, 40.
Bilotta, A., Ceroni, F., Nigro, E., Di Ludovico, M., Pecce, M., and Manfredi, G. (2011). “Bond efficiency of EBR and NSM FRP systems for strengthening of concrete members.” J. Compos. Constr., 757–772.
Bilotta, A., Ceroni, F., Nigro, E., and Pecce, M. (2014). “Strain assessment for design of NSM FRP systems for strengthening of RC members.” Constr. Build. Mater., 69, 143–158.
Blaschko, M. (2003). “Bond behaviour of CFRP strips glued into slits.” 6th Int. Symp. on FRP Reinforcement for Concrete Structures (FRPRCS-6), K. H. Tan, ed., World Scientific Publishing, Singapore, 205–214.
Ceroni, F., Barros, J. A. O., Pecce, M., and Ianniciello, M. (2013). “Assessment of non linear bond laws for near surface mounted systems in concrete elements.” Compos. Part B: Eng., 45(1), 666–681.
Ceroni, F., Bilotta, A., Nigro, E., and Pecce, M. (2012). “Bond behavior of FRP NSM systems in concrete elements.” Compos. Part B: Eng., 43(2), 99–109.
Chen, J. F., and Teng, J. G. (2001). “Anchorage strength models for FRP and steel plates bonded to concrete.” J. ASCE, 784–791.
CNR DT. (2013). “Guide for the design and construction of externally bonded FRP systems for strengthening existing structures.”, Advisory Committee on Technical Recommendation for Construction of National Research Council, Rome.
Costa, I. G., and Barros, J. A. O. (2013). “Critical analysis of fibre-reinforced polymer near-surface mounted double-shear pull-out tests.” Strain–Int. J. Exp. Mech., 49, 299–312.
De Lorenzis, L., Lundregen, K., and Rizzo, A. (2004). “Anchorage length of near surface mounted FRP bars for concrete strengthening—Experimental investigation and numerical modeling.” ACI Struct. J., 101(2), 269–278.
De Lorenzis, L., and Nanni, A. (2001). “Characterization of FRP rods as near-surface mounted reinforcement.” J. Compos. Constr., 114–121.
De Lorenzis, L., Rizzo, A., and La Tegola, A. (2002). “A modified pull-out test for bond of near surface mounted FRP rods in concrete.” Compos. Part B: Eng., 33(8), 589–603.
De Lorenzis, L., and Teng, J. G. (2007). “Near-surface mounted FRP reinforcement: An emerging technique for structural strengthening.” Compos. Part B: Eng., 38(2), 119–143.
Guadagnini, M., et al. (2012). “Round robin test on the bond behavior of externally bonded FRP systems to concrete.” 6th Int. Conf. on FRP Composites in Civil Engineering (CICE2012), Rome.
Hassan, T., and Rizkalla, S. (2003). “Investigation of bond concrete structures strengthened with near surface mounted carbon fiber reinforced polymer strips.” J. Compos. Constr., 248–257.
Horiguchi, T., and Saeki, N. (1997). “Effect of test methods and quality of concrete on bond strength of CFRP sheet.” 3rd Int. Symp. on Non-metallic (FRP) Reinforcement for Concrete Structures (FRPRCS-3), Sapporo, Japan, 265–270.
ISO. (2008). “Non-conventional reinforcement of concrete—Test methods—Part 1: Fiber reinforced polymer (FRP) bars and grids.”, 48.
Mazzotti, C., Savoia, M., and Ferracuti, B. (2009). “A new single-shear set-up for stable debonding of FRP-concrete joints.” Constr. Build. Mater., 23(4), 1529–1537.
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, 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., and Oehlers, D. J. (2007b). “Generic debonding resistance of EB and NSM plate-to concrete joints.” J. Compos. Constr., 62–70.
Ueda, T., and Dai, J. G. (2005). “Interface of fiber reinforced polymer laminates externally bonded to concrete substrate: From test methods to bond modeling.” Int. Symp. on Bond Behaviour of FRP in Structures (BBFS 2005), Hong Kong, J. F. Chen, and J. G. Teng, eds., Hong Kong Polytechnic Univ., Hong Kong, 23–34.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 20 • Issue 1 • February 2016
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Jun 27, 2014
Accepted: Mar 12, 2015
Published online: Jun 2, 2015
Discussion open until: Nov 2, 2015
Published in print: Feb 1, 2016
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.