New Approach for Modeling the Contribution of NSM FRP Strips for Shear Strengthening of RC Beams
Publication: Journal of Composites for Construction
Volume 14, Issue 1
Abstract
This paper presents the main features of an analytical model recently developed to predict the near-surface mounted (NSM) fiber-reinforced polymer (FRP) strips shear strength contribution to a reinforced concrete (RC) beam throughout the beam’s loading process. It assumes that the possible failure modes that can affect the ultimate behavior of an NSM FRP strip comprise: loss of bond (debonding); concrete semiconical tensile fracture; mixed shallow-semicone-plus-debonding; and strip tensile fracture. That model was developed by fulfilling equilibrium, kinematic compatibility, and constitutive law of both the adhered materials and the bond between them. The debonding process of an NSM FRP strip to concrete was interpreted and closed-form equations were derived after proposing a new local bond stress-slip relationship. The model proposed also addressed complex phenomena such as the interaction between the force transferred to the surrounding concrete through bond stresses and concrete fracture as well as the interaction among adjacent strips. The main features of the proposed modeling strategy are shown along with the main underlying physical-mechanical concepts and assumptions. Using recent experimental data, the predictive performance of the model is assessed. The model is also applied to single out the influence of relevant parameters on the NSM technique effectiveness for the shear strengthening of RC beams.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The writers of the present work wish to acknowledge the support provided by the “Empreiteiros Casais,” S&P, degussa Portugal, and Secil (Unibetão, Braga). The study reported in this paper forms a part of the research program “SmartReinforcement—Carbon fibre laminates for the strengthening and monitoring of reinforced concrete structures” supported by ADI-IDEIA, Project No. UNSPECIFIED13-05-04-FDR-00031. Also, this work was carried out under the auspices of the Italian DPC-ReLuis Project (Repertory No. UNSPECIFIED540), Research Line 8, whose financial support is greatly appreciated.
References
Bianco, V. (2008). “Shear strengthening of RC beams by means of NSM FRP strips: Experimental evidence and analytical modeling.” Ph.D. thesis, Dept. of Structural Engrg. and Geotechnics, Sapienza Univ. of Rome, Italy.
Bianco, V., Barros, J. A. O., and Monti, G. (2006). “Shear strengthening of RC beams by means of NSM laminates: Experimental evidence and predictive models.” Technical Rep. No. 06-DEC/E-18, Dept. Civil Eng., School Eng. University of Minho, Guimarães, Portugal.
Bianco, V., Barros, J. A. O., and Monti, G. (2007a). “A new approach for modeling the NSM shear strengthening contribution in reinforced concrete beams.” Proc., FRPRCS-8, University of Patras, Greece.
Bianco, V., Barros, J. A. O., and Monti, G. (2007b). “Shear strengthening of RC beams by means of NSM strips: A proposal for modeling debonding.” Technical Rep. No. 07-DEC/E-29, Dept. Civil Eng., School Eng. University of Minho, Guimarães, Portugal.
Bianco, V., Barros, J. A. O., and Monti, G. (2009). “Bond model of NSM FRP strips in the context of the shear strengthening of RC beams.” J. Struct. Eng., 135(6), 619–631.
CEB-FIP Model Code 90. (1993). Bulletin d’Information No. 213/214, Thomas, Telford, London.
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.
Dias, S. J. E. (2008). “Experimental and analytical research in the shear strengthening of reinforced concrete beams using the near-surface mounted technique with CFRP strips.” Ph.D. thesis, Dept. of Civil Engineering, Univ. of Minho, Guimarães, Portugal (in Portuguese).
Dias, S. J. E., and Barros, J. A. O. (2008). “Shear strengthening of T cross section reinforced concrete beams by near-surface mounted technique.” J. Compos. Constr., 12(3), 300–311.
Dias, S. J. E., Bianco, V., Barros, J. A. O., Monti, G., (2007). “Low strength concrete T cross section RC beams strengthened in shear by NSM technique.” Proc., Workshop—Materiali ed Approcci Innovativi per il Progetto in Zona Sismica e la Mitigazione della Vulnerabilità delle Strutture, University of Salerno, Italy.
Mohamed Ali, M. S., Oehlers, D. J., and Seracino, R. (2006). “Vertical shear interaction model between external FRP transverse plates and internal stirrups.” Eng. Struct., 28, 381–389.
Monti, G., and Liotta, M. ’A. (2007). “Tests and design equations for FRP-strengthening in shear.” Constr. Build. Mater., 21(4), 799–809.
Nanni, A., Di Ludovico, M., and Parretti, R. (2004). “Shear strengthening of a PC bridge girder with NSM CFRP rectangular bars.” Adv. Struct. Eng., 7(4), 297–309.
Rizzo, A., and De Lorenzis, L. (2009). “Behaviour and capacity of RC beams strengthened in shear with NSM FRP reinforcement.” Constr. Build. Mater., 23, 1555–1567.
Sena-Cruz, J. M. (2004). “Strengthening of concrete structures with near-surface mounted CFRP laminate strips.” Ph.D. thesis, Dept. of Civil Engineering, Univ. of Minho, Guimarães, Portugal.
Sena-Cruz, J. M., and Barros, J. A. O. (2004). “Bond between near-surface mounted CFRP laminate strips and concrete in structural strengthening.” J. Compos. Constr., 8(6), 519–527.
Teng, J. G., and De Lorenzis, L., Wang, B., Rong, L., Wong, T. N., and Lik, L. (2006) “Debonding failures of RC beams strengthened with near-surface mounted CFRP strips.” J. Compos. Constr., 10(2), 92–105.
Teng, J. G., Lam, L., and Chen, J. F. (2004). “Shear strengthening of RC beams with FRP composites.” Prog. Struct. Eng. Mater., 6, 173–184.
Triantafillou, T. C., and Antonopoulos, C. P. (2000). “Design of concrete flexural members strengthened in shear with FRP.” J. Compos. Constr., 4(4), 198–205.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 14 • Issue 1 • February 2010
Pages: 36 - 48
Copyright
© 2010 ASCE.
History
Received: Sep 30, 2008
Accepted: Apr 19, 2009
Published online: Jan 15, 2010
Published in print: Feb 2010
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.