Near-Surface-Mounted CFRP for Strengthening Concavely Curved Soffit RC Beams: Experimental and Analytical Investigation
Publication: Journal of Composites for Construction
Volume 26, Issue 5
Abstract
Near-surface-mounted (NSM) carbon fiber–reinforced polymers (CFRPs) have emerged as a promising strengthening technique to improve the flexural performance of reinforced-concrete (RC) structures. Although these systems have been investigated extensively for flat soffit RC beams, their performance when applied to concavely curved soffit members requires investigation. This paper presents the results of an experimental program conducted to investigate the behavior of concavely curved soffit RC beams strengthened in flexure with NSM CFRP rods. Twenty RC beams were designed, fabricated, and statically tested, including 15 beams that contained curved soffits with varying degrees of curvature ranging between 5 to 20 mm/m. The remaining five beams were flat soffit and were used as control beams. The ultimate capacity, failure mode, flexural stiffness, ductility, and level of FRP strain prior to debonding of these beams are analyzed and discussed. This study identifies gaps in existing design guidelines and codes and presents recommendations for designers on NSM technology.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The joint scholarship support provided to the first author by the Iraqi Ministry of Higher Education and Scientific Research and the Swinburne University of Technology is gratefully acknowledged. The authors wish to acknowledge the technical support provided by the staff of the Smart Structures Laboratory at Swinburne University of Technology. The support of BASF (Australia) for supplying all the FRP and epoxy material used is gratefully acknowledged.
References
Abdallah, M., F. Al Mahmoud, M. Tabet-Derraz, A. Khelil, and J. Mercier. 2021. “Experimental and numerical investigation on the effectiveness of NSM and side-NSM CFRP bars for strengthening continuous two-span RC beams.” J. Bridge Eng. 41: 102723. https://doi.org/10.1016/j.jobe.2021.102723.
ACI (American Concrete Institute). 2017. Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures. ACI 440.2R-17. Farmington Hills, MI: ACI.
Al-Ghrery, K., R. Al-Mahaidi, R. Kalfat, N. Oukaili, and A. Al-Mosawe. 2021a. “Flexure strengthening of concrete bridge girders with concavely curved soffit using near-surface-mounted CFRP bars.” In Proc., 10th Int. Conf. on Bridge Maintenance, Safety and Management. London: Taylor & Francis Group.
Al-Ghrery, K., R. Al-Mahaidi, R. Kalfat, N. Oukaili, and A. Al-Mosawe. 2021b. “Comprehensive experimental study on concavely-curved soffit reinforced concrete beams externally-bonded with FRP.” In Proc., 10th Int. Conf. on FRP Composites in Civil Engineering. New York: Springer.
Al-Ghrery, K., R. Al-Mahaidi, R. Kalfat, N. Oukaili, and A. Al-Mosawe. 2022. “Externally bonded CFRP for flexural strenging of RC beams with different levels of soffit curvature.” J. Compos. Constr. 26 (1): 1–11. https://doi.org/10.1061/(ASCE)CC.1943-5614.0001176.
AS (Australian Standard). 2017. Rehabilitation and strengthening of existing bridges. AS 5100.8. Sydney, Australia: AS.
ASTM. 2014. Standard test method for static modulus of elasticity and Poisson’s ratio of concrete in compression. C469/C469M-14. Philadelphia, PA: ASTM.
ASTM. 2017a. Standard test method for splitting tensile strength of cylindrical concrete specimens. C496/C496M-17. Philadelphia, PA: ASTM.
ASTM. 2017b. Standard test method for tensile properties of polymer matrix composite materials. D3039/D3039M-17. Philadelphia, PA: ASTM.
ASTM. 2018a. Standard specification for deformed and plain carbon-steel bars for concrete reinforcement. A615/A615M-18e1. Philadelphia, PA: ASTM.
ASTM. 2018b. Standard test method for compressive strength of cylindrical concrete specimens. C39/C39M-18. Philadelphia, PA: ASTM.
CS (Concrete Society). 2012. Design guidance for structures using fiber. Concrete Society Working Party. Technical Rep. No. 55. Surrey, UK: CS.
De Lorenzis, L., and A. Nanni. 2002. “Bond between near surface mounted fibre-reinforced polymer rods and concrete in structural strengthening.” ACI Struct. J. 99 (2): 123–132.
De Lorenzis, L., and J. G. Teng. 2007. “Near-surface mounted FRP reinforcement: An emerging technique for strengthening structures.” Composites, Part B 38 (2): 119–143. https://doi.org/10.1016/j.compositesb.2006.08.003.
Eshwar, N., T. Ibell, and A. Nanni. 2005. “Effectiveness of CFRP strengthening on curved soffit RC beams.” Adv. Struct. Eng. 8 (1): 55–68. https://doi.org/ 10.1260/1369433053749607.
Novidis, D., S. J. Pantazopoulou, and E. Tentolouris. 2007. “Experimental study of bond of NSM–FRP reinforcement.” Constr. Build. Mater. J. 21 (8): 1760–1770. https://doi.org/10.1016/j.conbuildmat.2006.05.054.
Porter, A., S. Denton, A. Nanni, and T. Ibell. 2003. “Effectiveness of frp plate strengthening on curved soffits.” In Proc., 6th Int. Symp. on FRP Reinforcement for Concrete Structures, 1147–1156. New York: River Edge.
Zhang, Y., M. Elsayed, L. V. Zhang, and M. L. Nehdi. 2021. “Flexural behaviour of reinforced concrete T-section beams strengthened by NSM FRP bars.” J. Eng. Struct. 233: 111922. https://doi.org/10.1016/j.engstruct.2021.111922.
Zhu, H., S. Cheng, D. Gao, S. Neaz, and C. Li. 2018. “Flexural behaviour of partially fiber-reinforced high-strength concrete beams reinforced with FRP bars.” Constr. Build. Mater. J. 161 (10): 587–597. https://doi.org/10.1016/j.conbuildmat.2017.12.003.
Information & Authors
Information
Published In
Copyright
© 2022 American Society of Civil Engineers.
History
Received: Oct 9, 2021
Accepted: May 8, 2022
Published online: Jul 19, 2022
Published in print: Oct 1, 2022
Discussion open until: Dec 19, 2022
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.