Flexural Strengthening of Continuous Reinforced Concrete Beams with Near-Surface-Mounted Reinforcement
Publication: Practice Periodical on Structural Design and Construction
Volume 24, Issue 3
Abstract
This experimental study attempts to investigate the flexural behavior of continuous reinforced concrete (RC) beams strengthened by near-surface-mounted steel bars. The tests were conducted on 11 3,000-mm specimens with cross-sectional dimensions of 150 × 225 mm. The longitudinal reinforcement of all beams consisted of two ϕ10 steel bars in the negative and positive moment regions. To ensure that the beams would fail under flexure rather than shear, ϕ10 stirrups were spaced at 100 mm c/c over the entire beam length. The first beam was not strengthened and was considered a control beam. The other specimens were strengthened by near-surface-mounted bars with different development lengths, diameters, and material types, with end-anchors of carbon-fiber-reinforced polymer (CFRP) fabrics. The test was conducted under two-point loads, applied at the center (1,400 mm) of the span. The main investigated characteristics were cracking and ultimate loads, crack width, displacement, and failure modes. From the experiments, all the strengthened beams achieved a significant enhancement in ultimate flexural strength by approximately 108% relative to the control beam. In addition, CFRP end-anchorage can eliminate the separation of the concrete cover and demonstrates a significant improvement in ductility.
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References
ACI (American Concrete Institute). 2014. Building code requirements for structural concrete. ACI 318M-14. Farmington Hills, MI: ACI.
Augustine, F. W. 2013. “Strengthening rectangular beams with NSM steel bars and externally bonded GFRP.” M.Sc. thesis, Dept. of Civil Engineering, College of Engineering, Kansas State Univ.
De Lorenzis, L. D., and J. G. Teng. 2007. “Near-surface mounted FRP reinforcement: An emerging technique for strengthening structures.” Composites Part B: Eng. 38 (2): 119–143. https://doi.org/10.1016/j.compositesb.2006.08.003.
El-Refaie, S. A., A. F. Ashour, and S. W. Garrity. 2003. “Sagging and hogging strengthening of continuous reinforced concrete beams using CFRP sheets.” ACI Struct. J. 100 (4): 446–453.
Epoxy Works. 2014. “Cold-temperature bonding & coating with epoxy.” Accessed April 19, 2014. https://www.epoxyworks.com/index.php/cold-temperature-bonding-coating-with-epoxy/.
Hosen, M. A., M. Z., Jumaat, U. J. Alengaram, A. B. M. Saiful Islam, and H. bin Hashim. 2016. “Near surface mounted composites for flexural strengthening of reinforced concrete beams.” J. Polym. 8 (3): 67. https://doi.org/10.3390/polym8030067.
Hosen, M. A., M. Z. Jumaat, K. H. Mahfuz, U. D. Darain, M. Obaydullah, and A. B. M. Saiful Islam. 2014. “Flexural strengthening of RC beams with NSM steel bars.” In Proc., Int. Conf. Food, Agric. Biol. (FAB-2014), 8–13. Kuala Lumpur, Malaysia: IICBE.
Hosen, M. A., M. Z. Jumaat, and A. B. M. Saiful Islam. 2015. “Side near surface mounted (SNSM) technique for flexural enhancement of RC beams.” Mater. Des. 83 (Oct): 587–597. https://doi.org/10.1016/j.matdes.2015.06.035.
Khalifa, A., G. Tumialan, A. Nanni, and A. Belarbi. 1999. “Shear strengthening of continuous RC beams using externally bonded CFRP sheets.” In Proc., 4th Int. Symp. on FRP for Reinforcement of Concrete Structures (FRPRCS4), 995–1008. Baltimore, MD: ACI.
Khalil, A. A., E. E. Etman, and A. H. El-Masry. 2015. “Behavior of reinforced concrete continuous beams strengthened with near surface mounted reinforcement.” In Proc., Int. Conf. on Advances in Structural and Geotechnical Engineering, 1–17. Hurghada, Egypt: ICASGE.
Nordin, H., and T. Björn. 2006. “Concrete beams strengthened with prestressed near surface mounted CFRP.” J. Compos. Constr. 10 (1): 60–68. https://doi.org/10.1061/(ASCE)1090-0268(2006)10:1(60).
Rizzo, A., and L. De Lorenzis. 2009. “Behavior and capacity of RC beams strengthened in shear with NSM FRP reinforcement.” Constr. Build. Mater. 23 (4): 1555–1567. https://doi.org/10.1016/j.conbuildmat.2007.08.014.
Sikadur-30 Product Data Sheet. 2017. “Thixotropic epoxy adhesive for bonding reinforcement.” No. 2, May, 2–5.
Sun, Z. Y., G. Wu, Z. S. Wu, and Y. B. Luo. 2011. “Flexural strengthening of concrete beams with near-surface mounted steel-fiber-reinforced polymer composite bars.” J. Reinf. Plast. Compos. 30 (18): 1529–1537. https://doi.org/10.1177/0731684411427209.
Zhang, D., T. Ueda, and H. Furuuchi. 2012. “A design proposal for concrete cover separation in beams strengthened by various externally bonded tension reinforcements.” J. Adv. Concr. Technol. 10 (9): 285–300. https://doi.org/10.3151/jact.10.285.
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Published In
Practice Periodical on Structural Design and Construction
Volume 24 • Issue 3 • August 2019
Copyright
© 2019 American Society of Civil Engineers.
History
Received: Jun 25, 2018
Accepted: Feb 6, 2019
Published online: Apr 30, 2019
Published in print: Aug 1, 2019
Discussion open until: Sep 30, 2019
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