Composite Strips with U-Shaped CFRP Wrap Anchor Systems for Strengthening Reinforced Concrete Beams

  • Rami H. HaddadEmail author
  • Catreen S. Marji
Research paper


The contribution of carbon fiber reinforced polymer (CFRP) wrap as an anchorage system of CFRP plates, used for flexural strengthening, is investigated. Eighteen concrete beams (100 × 150 × 1400 mm3) were cast and cured for 28 days before strengthening with both CFRP plates (1.2 × 50 mm2) and anchorage-used, U-shaped CFRP wraps. These were adhered on the top of the CFRP plates at different longitudinal and transverse extensions. The mechanical response of the concrete beams was examined under four-point loading including measurements of load versus deflection, bond stress versus slippage and strain in CFRP plates. Crack formation and failure modes were also monitored and characterized. End anchorage regimes, using 300-mm-long U-shaped segmented CFRP wraps, impart the best improvement to load capacity, rigidity, and toughness (up to 80, 57, and 40%, respectively) without harming tangibly ductility in terms of deflection at failure. Anchorage cases involving attaching continuous single or double layers of U-shaped CFRP wrap on the top of CFRP plates impart lower but tangible overall improvements in mechanical performance of CFRP-strengthened beams. A simple empirical model is developed to predict ultimate strain in CFRP plate based on present results before examining using available literature data. Moreover, the efficiency of the present technique is compared to that present in literature.


Beams Composite materials Bond CFRP wrap anchorage Strain in CFRP Failure patterns 



The authors acknowledge the technical and financial support provided by Jordan University of Science and Technology (Project No. 227/2011) and the technical assistance provided by the structural and materials laboratories teams.


  1. 1.
    Haddad RH, Shannaq M, Hamad R (2007) Repair of heat-damaged reinforced concrete T-beams Using FRC Jackets. Mag Concr Res 59(4):223–231. CrossRefGoogle Scholar
  2. 2.
    Haddad RH, Shannag M, Moh’s A (2008) Repair of heat-damaged shallow beams using advanced campsites. Mater Struct 41:287–299. CrossRefGoogle Scholar
  3. 3.
    Ombres L, Verre S (2018) Shear performance of FRCM strengthened RC beams. In: Proceedings of the American Concrete Institute, vol 324-07. ACI Special Publication, pp 1–22Google Scholar
  4. 4.
    Ombres L, Mancuso N, Mazzuca S, Verre S (2019) Bond between carbon fabric-reinforced cementitious matrix and masonry substrate. J Mater Civ Eng. Google Scholar
  5. 5.
    MacDonald M, Calder A (1990) Bonded steel plating for strengthening concrete structures. Int J Adhes Ashes 2(2):119–127. CrossRefGoogle Scholar
  6. 6.
    Jones R, Swamy R, Charif A (1988) Plate separation and anchorage of reinforced concrete beams strengthened by epoxy-bonded steel strips. Struct Eng 66(5):85–94Google Scholar
  7. 7.
    Hussain M, Sharif A, Basunbul I, Baluch M, Al-Sulaimani G (1995) Flexural behavior of precracked reinforced concrete beams strengthened externally by steel strips. ACI Struct J 92(1):14–22. Google Scholar
  8. 8.
    Hsu C-T, Punurai W, Bian H, Jia Y (2003) Flexural strengthening of reinforced concrete beams using carbon fibre reinforced polymer strips. Mag Concr Res 55(3):279–288. CrossRefGoogle Scholar
  9. 9.
    Attari N, Amziane S, Chemrouk M (2012) Flexural strengthening of concrete beams using CFRP, GFRP and hybrid FRP sheets. Constr Build Mater 37(1):746–757. CrossRefGoogle Scholar
  10. 10.
    Lamanna AJ, Bank LC, David WS (2004) Flexural strengthening of reinforced concrete beams by mechanically attaching fiber-reinforced polymer strips. J Compos Constr 8(3):203–210. CrossRefGoogle Scholar
  11. 11.
    Adhikary B, Mutsuyoshi H (2006) Shear strengthening of reinforced concrete beams using various techniques. Constr Build Mater 20(6):366–373. CrossRefGoogle Scholar
  12. 12.
    Ekenel M, Myers J (2007) Durability performance of RC beams strengthened with epoxy injection and CFRP fabrics. Constr Build Mater 21(6):1182–1190. CrossRefGoogle Scholar
  13. 13.
    Jumaat MZ, Alam MD (2008) Behavior of U and L shaped end anchored steel strip strengthened reinforced concrete beams. Eur J Sci Res 22(2):184–196Google Scholar
  14. 14.
    Demacos C (2008) Investigating the influence of FRP sheet anchorage to structural response of reinforced concrete beams. In: International scientific conference SynEnergy Forum, Spetses, GreeceGoogle Scholar
  15. 15.
    Yashitake IE, Kim YJ, Yumikura K, Mimura Y (2009) Composite strips with various anchor systems for retrofitting concrete beams. Int J Concr Struct Mater 5(1):43–48. CrossRefGoogle Scholar
  16. 16.
    Khan AR (2009) Role of U-shaped anchorages on performance of RC beams strengthened by CFRP strips. In: Alexander M et al (eds) Concrete repair, rehabilitation and retrofitting II. Taylor & Francis Group, London, pp 1249–1253Google Scholar
  17. 17.
    Khan AA, Tehmina A (2010) Effectiveness of U-shaped CFRP wraps as end anchorages in predominant flexure and shear region. In: Proceedings of the 5th international conference on FRP composites in civil engineering (CICE 2010), Beijing, China, pp 533–536Google Scholar
  18. 18.
    Ahmed E, Sobuz HR, Sutan NM (2011) Flexural performance of CFRP strengthened RC beams with different degrees of strengthening schemes. Int J Phys Sci 6(9):2229–2238. Google Scholar
  19. 19.
    Zhang W, Smith T (2011) Influence of FRP anchor fan configuration and dowel angle on anchoring FRP strips. Comp B Eng 43(8):3516–3527. CrossRefGoogle Scholar
  20. 20.
    Xiang L, Xiang LG, Xiao BS, Yu O, Zhan LF (2013) Contribution of U-shaped strips to the flexural capacity of low-strength reinforced concrete beams strengthened with carbon fiber composite sheets. Comp B Eng. Google Scholar
  21. 21.
    Haddad RH, Almasaeid H (2016) Recovering shear capacity of heat-damaged beams using NSM-CFRP strips. Const Build Mater 105:448–458. CrossRefGoogle Scholar
  22. 22.
    Wu Y-F, Huang Y (2008) Hybrid bonding of FRP to reinforced concrete structures. J Compos Constr 12(3):266–273. CrossRefGoogle Scholar
  23. 23.
    Nguyen-Minha L, Phan-Vua P, Tran-Thanhc D et al (2018) Flexural-strengthening efficiency of CFRP sheets for unbonded post-tensioned concrete T-beams. Eng Struct 166:1–15. CrossRefGoogle Scholar
  24. 24.
    Haddad RH, Al-Rousan R, Ghanma L, Nimri Z (2015) Modifying CFRP-concrete bond characteristics from pull-out tests. Mag Concr Res 67(2):89–103. CrossRefGoogle Scholar
  25. 25.
    ACI Committee 440 (2008) Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures (440.2R-08). American Concrete Institute, Farmington Hills, p 76Google Scholar
  26. 26.
    American Concrete Institute (2008) Building code requirements for structural concrete and commentary (ACI-318). American Concrete Institute, Farmington HillsGoogle Scholar
  27. 27.
    ASTM International (2004) American society for testing and materials international (ASTM). ASTM International, West ConshohockenGoogle Scholar
  28. 28.
    ACI Manual of Concrete Practice (2008) Standard practice for selecting proportions for normal, heavyweight, and mass concrete (ACI 211.1). Part I: materials and general properties of concrete, p 92Google Scholar
  29. 29.
    Haddad R, Marji C, Al-Rousan R (2016) An effective anchorage system for reinforced concrete beams with fiber reinforced polymer composites. In: The fifth international symposium on life-cycle civil engineering, Delft, Netherlands.
  30. 30.
    Grelle SV, Sneed LH (2013) Review of anchorage systems for externally bonded FRP laminates. Int J Concr Struct Mater 7(1):17–33. CrossRefGoogle Scholar
  31. 31.
    Wu G, Wu Z, Jiang J, Tian Y, Zhang M (2015) Experimental study of RC beams strengthened with distributed pre-stressed high-strength steel wire rope. Mag Concr Res 62(4):253–265. CrossRefGoogle Scholar
  32. 32.
    Haddad R (2016) Hybrid repair configurations with CFRP composites for recovering structural performance of steel-corroded beams. Constr Build Mater 124:508–518. CrossRefGoogle Scholar

Copyright information

© Iran University of Science and Technology 2019

Authors and Affiliations

  1. 1.Civil Engineering DepartmentJordan University of Science and TechnologyIrbidJordan

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