Polyurethane-FRP External Strengthening of RC Beams with No Steel Stirrups
Publication: Journal of Composites for Construction
Volume 23, Issue 1
Abstract
Externally bonded (EB) fiber-reinforced polymer (FRP) composites are an effective means for the strengthening of shear-deficient reinforced concrete flexural members. Previous studies have predominantly employed epoxy-based wet layup systems. In this study, carbon FRP preimpregnated with polyurethane resin is utilized in strengthening shear-deficient RC beams and compared with an epoxy resin. Fourteen small-scale () and five large-scale () flexural specimens were tested, considering FRP type (polyurethane, epoxy), size effect, shear span-to-depth ratio, FRP configuration (U-wraps, side bonding), and FRP scheme (sheets, strips at 45° or 90°). Four-point loading tests demonstrated similar or enhanced shear capacity for the polyurethane-strengthened RC beams compared to the epoxy-strengthened beams. A mechanics-based analytical model, utilizing the principle of effective FRP stress and the upper-bound theorem of limit analysis, illustrated that the shear behavior and debonding mechanism were dependent on both FRP composite and bond characteristics.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors would like to thank Neptune Research, Inc. (NRI) for providing the composite materials. All experiments were conducted at the Burton, Braswell, Middlebrooks Structures Laboratory of the University of Central Florida. The first author would like to acknowledge the financial support of the Higher Committee for Education Development in Iraq (HCED).
References
ACI (American Concrete Institute). 1995. Control of deflection in concrete structures. ACI 435R. Farmington Hills, MI: ACI.
ACI (American Concrete Institute). 2014. Building code requirements for structural concrete. ACI 318M and Commentary ACI 318RM. Farmington Hills, MI: ACI.
ACI (American Concrete Institute). 2017. Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures. ACI 440.2R. Farmington Hills, MI: ACI.
Adhikary, B. B., H. Mutsuyoshi, and M. Ashraf. 2004. “Shear strengthening of reinforced concrete beams using fiber-reinforced polymer sheets with bonded anchorage.” ACI Struct. J. 101 (5): 660–668.
Al-Jelawy, H. 2013. “Experimental and numerical investigations on bond durability of CFRP strengthened concrete members subjected to environmental exposure.” M.S. thesis, Dept. of Civil, Environmental, and Construction Engineering, Univ. of Central Florida.
ASTM. 2016a. Standard specification for deformed and plain carbon-steel bars for concrete reinforcement. ASTM A615/A615M. West Conshohocken, PA: ASTM.
ASTM. 2016b. Standard test method for compressive strength of cylindrical concrete specimens. ASTM C39/C39M. West Conshohocken, PA: ASTM.
ASTM. 2016c. Standard test methods for tension testing of metallic materials. ASTM E8/E8M. West Conshohocken, PA: ASTM.
ASTM. 2017. Standard test method for determining tensile properties of fiber reinforced polymer matrix composites used for strengthening of civil structures. ASTM D7565/D7565M. West Conshohocken, PA: ASTM.
Batchelor, B., H. K. George, and T. I. Campbell. 1986. “Effectiveness factor for shear in concrete beams.” J. Struct. Eng. 112 (6): 1464–1477. https://doi.org/10.1061/(ASCE)0733-9445(1986)112:6(1464).
Bazinet, S., L. Cercone, and F. Worth. 2003. “Composite FRP moves into underwater repair applications.” SAMPE J. 39 (3): 8–16.
Belarbi, A., S. Bae, D. Kuchma, A. Mirmiran, and A. Okeil. 2011. Design of FRP systems for strengthening concrete girders in shear. Washington, DC: Transportation Research Board.
Braestrup, M. W. 1974. “Plastic analysis of shear in reinforced concrete.” Mag. Concr. Res. 26 (89): 221–228.
Burchardt, B. 2010. “Advances in polyurethane structural adhesives.” In Advances in structural adhesive bonding, 35–65. Switzerland: Sika Services AG.
Carolin, A., and B. Täljsten. 2005. “Experimental study of strengthening for increased shear bearing capacity.” J. Compos. Constr. 9 (6): 488–496. https://doi.org/10.1061/(ASCE)1090-0268(2005)9:6(488).
Chaallal, O., M. J. Nollet, and D. Perraton. 1998. “Shear strengthening of RC beams by externally bonded side CFRP strips.” J. Compos. Constr. 2 (2): 111–113. https://doi.org/10.1061/(ASCE)1090-0268(1998)2:2(111).
Chen, J. F., and J. G. Teng. 2003. “Shear capacity of FRP-strengthened RC beams: FRP debonding.” Constr. Build. Mater. 17 (1): 27–41. https://doi.org/10.1016/S0950-0618(02)00091-0.
Concrete Society. 2012. Design guidance for strengthening concrete structures using fibre composite materials. Camberley, UK: British Cement Association.
El Zghayar, E., K. Mackie, and J. Xia. 2014. “Fiber reinforced polymer FRP composites in retrofitting of concrete structures: Polyurethane systems versus epoxy systems.” ACI Spec. Publ. 298: 1–22.
fib (International Federation for Structural Concrete). 2001. Externally bonded FRP reinforcement for RC structures. Lausanne, Switzerland: fib.
Grande, E., M. Imbimbo, and A. Rasulo. 2013. “Experimental response of RC beams strengthened in shear by FRP sheets.” Open Civ. Eng. J. 7 (1): 127–135. https://doi.org/10.2174/1874149501307010127.
Haber, Z. B., K. R. Mackie, and L. Zhao. 2012. “Mechanical and environmental loading of concrete beams strengthened with epoxy and polyurethane matrix carbon fiber laminates.” Constr. Build. Mater. 26 (1): 604–612. https://doi.org/10.1016/j.conbuildmat.2011.06.063.
Italian National Research Council. 2013. Guide for the design and construction of externally bonded FRP systems for strengthening existing structures. Rome: Italian National Research Council.
JSCE (Japan Society of Civil Engineers). 2001. Recommendations for upgrading of concrete structures with use of continuous fiber sheets. Tokyo: JSCE.
Khalifa, A., W. J. Gold, A. Nanni, and A. A. Mi. 1998. “Contribution of externally bonded FRP to shear capacity of RC flexural members.” J. Compos. Constr. 2 (4): 195–202. https://doi.org/10.1061/(ASCE)1090-0268(1998)2:4(195).
Khalifa, A., and A. Nanni. 2000. “Improving shear capacity of existing RC T-section beams using CFRP composites.” Cem. Concr. Compos. 22 (3): 165–174. https://doi.org/10.1016/S0958-9465(99)00051-7.
Khalifa, A., and A. Nanni. 2002. “Rehabilitation of rectangular simply supported RC beams with shear deficiencies using CFRP composites.” Constr. Build. Mater. 16 (3): 135–146. https://doi.org/10.1016/S0950-0618(02)00002-8.
Leung, C. K. Y., Z. Chen, S. Lee, M. Ng, M. Xu, and J. Tang. 2007. “Effect of size on the failure of geometrically similar concrete beams strengthened in shear with FRP strips.” J. Compos. Constr. 11 (5): 487–496. https://doi.org/10.1061/(ASCE)1090-0268(2007)11:5(487).
Lim, T. Y., P. Paramasivam, and S. L. Lee. 1987. “Shear and moment capacity of reinforced steel-fibre-concrete beams.” Mag. Concr. Res. 39 (140): 148–160. https://doi.org/10.1680/macr.1987.39.140.148.
Mofidi, A., and O. Chaallal. 2011. “Shear strengthening of RC beams with externally bonded FRP composites: Effect of strip-width-to-strip-spacing ratio.” J. Compos. Constr. 15 (5): 732–742. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000219.
Monti, G., and M. A. Liotta. 2007. “Tests and design equations for FRP-strengthening in shear.” Constr. Build. Mater. 21 (4): 799–809. https://doi.org/10.1016/j.conbuildmat.2006.06.023.
Monti, G., F. Santinelli, and M. A. Liotta. 2004. “Mechanics of FRP shear strengthening of RC beams.” In Proc., 11th European Conf. on Composite Materials, 11. Rhodes, Greece.
Neubauer, U., and F. S. Rostasy. 1999. “Bond failure of concrete fiber reinforced polymer plates at inclined cracks—Experiments and fracture mechanics model.” ACI Spec. Publ. 188: 369–382.
Nielsen, M. P., and M. W. Braestrup. 1975. “Plastic shear strength of reinforced concrete beams.” Bygningsstatiske Meddelelser 46 (3): 61–99.
Nielsen, M. P., and L. C. Hoang. 2011. Limit analysis and concrete plasticity. Hoboken, NJ: CRC Press.
Petrone, F., and G. Monti. 2014. “FRP-RC beam in shear: Mechanical model and assessment procedure for pseudo-ductile behavior.” Polymers 6 (7): 2051–2064. https://doi.org/10.3390/polym6072051.
Reineck, K. H. 1991. “Ultimate shear force of structural concrete members without transverse reinforcement derived from a mechanical model (SP-885).” ACI Struct. J. 88 (5): 592–602.
Sen, R., and G. Mullins. 2007. “Application of FRP composites for underwater piles repair.” Compos. Part B: Eng. 38 (5–6): 751–758. https://doi.org/10.1016/j.compositesb.2006.07.011.
Sim, J., G. Kim, C. Park, and M. Ju. 2005. “Shear strengthening effects with varying types of FRP materials and strengthening methods.” ACI SP. 230: 1665–1680.
Täljsten, B., and L. Elfgren. 2000. “Strengthening concrete beams for shear using CFRP-materials: Evaluation of different application methods.” Compos. Part B: Eng. 31 (2): 87–96. https://doi.org/10.1016/S1359-8368(99)00077-3.
Triantafillou, T. C., and C. P. Antonopoulos. 2000. “Design of concrete flexural members strengthened in shear with FRP.” J. Compos. Constr. 4 (4): 198–205. https://doi.org/10.1061/(ASCE)1090-0268(2000)4:4(198).
Uji, K. 1992. “Improving shear capacity of existing reinforced concrete members by applying carbon fiber sheets.” Trans. Jpn. Concr. Inst. 14 (253): 266.
Wu, Z., H. Yuan, and H. Niu. 2002. “Stress transfer and fracture propagation in different kinds of adhesive joints.” J. Eng. Mech. 128 (5): 562–573. https://doi.org/10.1061/(ASCE)0733-9399(2002)128:5(562).
Yuan, H., J. G. Teng, R. Seracino, Z. S. Wu, and J. Yao. 2004. “Full-range behavior of FRP-to-concrete bonded joints.” Eng. Struct. 26 (5): 553–565. https://doi.org/10.1016/j.engstruct.2003.11.006.
Zureick, A. H., B. R. Ellingwood, A. S. Nowak, D. R. Mertz, and T. C. Triantafillou. 2010. Recommended guide specification for the design of externally bonded FRP systems for repair and strengthening of concrete bridge elements. Washington, DC: Transportation Research Board.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 23 • Issue 1 • February 2019
Copyright
©2018 American Society of Civil Engineers.
History
Received: Dec 3, 2017
Accepted: Jul 25, 2018
Published online: Nov 23, 2018
Published in print: Feb 1, 2019
Discussion open until: Apr 23, 2019
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.