Design Considerations of Carbon Fiber Anchors
Publication: Journal of Composites for Construction
Volume 12, Issue 6
Abstract
Carbon fiber-reinforced polymer (CFRP) sheets can be used to strengthen existing reinforced concrete members. However, debonding (separation of the CFRP sheet from the concrete surface) may occur at less than 50% of CFRP sheet’s tensile capacity, implying that half of the CFRP material is ineffective in increasing the strength of a concrete member. The use of carbon fiber anchors can increase the amount of tension carried in the CFRP sheets. Forty specimens were tested to develop initial design parameters of carbon fiber anchors. Tests showed that by providing anchors with a total cross-sectional area at least two times greater than that of the longitudinal sheet, it was possible to fracture the CFRP sheets. The best results were obtained using a greater number of smaller anchors. Further, surface preparation is unimportant when the CFRP sheets were well anchored and a 1:4 transition slope can manage any offsets in surface level. The general anchor design was then implemented on a series of long beams and demonstrated that the full CFRP sheet tensile capacity can be realized without incurring limitations due to debonding.
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Acknowledgments
Funding from the National Science Foundation for this research is gratefully acknowledged. Composite materials were generously donated by Fyfe Co. LLC. All research was conducted at the University of Texas at Austin Ferguson Structural Engineering Laboratory (FSEL) and much appreciation goes to all the personnel and staff at FSEL, especially Dr. Jirsa, Dr. Bayrak, and Insung Kim.
References
American Concrete Institute (ACI). (2002). “Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures.” ACI 440.2R-02, Farmington Hills, Mich.
ASTM International. (2000). “ASTM D 3039/D3039M standard test method for tensile properties of polymer matrix composite materials.” Annual book of ASTM standards, West Conshohocken, Pa.
Bonacci, J. F., and Maalej, F. (2001). “Behavioral trends of RC beams strengthened with externally bonded FRP.” J. Compos. Constr., 5(2), 102–113.
Bramblett, R. M. (2000). “Strengthening of reinforced concrete beams using carbon fiber reinforced polymer composites.” Master of Science thesis, The Univ. of Texas at Austin, Austin, Tex.
Burr, A. C. (2004). “Recent development in the use of FRP anchors and masonry wall strengthening techniques.” The Structural Engineer, Sept. 2004.
Fyfe Co. LLC. (2005). “Tyfo systems for beams.” ⟨www.fyfeco.com⟩ (Jun. 6, 2005).
Ibell, T., and Nanni, A. (2003). “The effects of a curved soffit on FRP-strengthening of concrete bridges” UTC-R73, Report Center for Infrastructure Engineering Studies, Rolla, Mo.
Japanese Society of Civil Engineers (JSCE). (1997). “Recommendations for design and construction of concrete structures using continuous fibre reinforcing materials.” Concrete Engineering Series 23, A. Machida, ed., Tokyo.
Jinno, Y., and Tsukagishi, H. (1998). “Structural properties of RC walls strengthened by carbon fiber sheets.” Proc., Architectural Institute of Japan Annual Conf., AIJ, Fukuoda, Japan, 209–210.
Khalifa, A., Alkhrdaji, T., Nanni, A., and Lansburg, S. (1999). “Anchorage of surface mounted FRP reinforcement.” Concr. Int., 21(10), 49–54.
Kim, I. S. (2006). “Rehabilitation of poorly detailed RC structures using CFRP materials.” Master of Science thesis, The Univ. of Texas at Austin, Austin, Tex.
Kobayashi, K., Fujii, S., Yabe, Y., Tsukagoshi, H., and Sugiyama, T. (2001). “Advanced wrapping system with CF anchor-Stress transfer mechanism of CF anchor.” Proc., 5th Int Symp. on Fiber-Reinforced Polymer (FRP) Reinforcement for Concrete Structures, FRPRCS, Cambridge, U.K. 379–388.
Morphy, R. D. (1999). “Behavior of fiber reinforced polymer (FRP) stirrups as shear reinforcement for Concrete Structures.” Master of Science thesis, Univ. of Manitoba, Winnipeg Ma., Canada.
Orton, S. L. (2007). “Development of a CFRP system to provide continuity in existing reinforced concrete buildings vulnerable to progressive collapse.” Dissertation, Univ. of Texas at Austin, Austin, Tex.
Orton, S. L., Jirsa, J. O., and Bayrak, O. (2006). “Anchorage of carbon fiber reinforced polymer sheets with and without height transition.” Proc., 3rd Int. Conf. on FRP Composites in Civil Engineering, CICE, Miami, 665–668.
Orton, S. L., Jirsa, J. O., and Bayrak, O. (2007). “The use of CFRP to provide continuity in reinforced concrete buildings vulnerable to progressive collapse.” Proc., 8th Int. Symp. on Fiber-Reinforced Polymer (FRP) Reinforcement for Concrete Structures (CD-ROM), FRPRCS, Patras, Greece.
Özdemir, G. (2005). “Mechanical properties of CFRP anchorages.” Master of Science thesis, Middle East Technical Univ., Istanbul, Turkey.
Saaticoglu, M., Serrato, F., and Foo, S. (2005). “Seismic performance of masonry infill walls retrofitted with CFRP sheets.” Proc., 7th Int. Symp. on Fiber-Reinforced Polymer (FRP) Reinforcement for Concrete Structures, FRPRCS, Kansas City, Mo., 341–353.
Sika. (2005). Sika CarboDur composite strengthening systems, ⟨www.sikausa.com⟩ (May, 6, 2005).
Teng, J. G., Chen, J. F., Smith, S. T., and Lam, L. (2001). FRP-strengthened RC structures, Wiley, New York.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 12 • Issue 6 • December 2008
Pages: 608 - 616
Copyright
© 2008 ASCE.
History
Received: Oct 22, 2007
Accepted: Feb 7, 2008
Published online: Dec 1, 2008
Published in print: Dec 2008
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