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Experimental Analysis of RC Elements Strengthened with CFRP Strips

This work is the result of experimental research conducted to determine the contribution of a composite material to improving the mechanical behavior of old, full-size reinforced T-beams in operation conditions under the action of short-term loads. The tension side of their ribs were strengthened by carbon strips of different lengths. Then, they were tested in loading by concentrated and uniformly distributed short-term loads. It was concluded that, for strengthening simply supported beams, there was no need for using CFRP strips longer than half of their length, and a lateral anchorage was not required. This refers to bending tests where no load increment exceeding 60% of the flexural strength is expected. The results obtained from this experiment may be of use in modern engineering practices, especially because tests conducted on old, full-size samples are very rare.

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  1. R. Folić and M. Malešev, “Održavanje i sanacija konstrukcija,” Materijali i Konstrukcije, 48, No. 4, 62-80 (2005).

    Google Scholar 

  2. O. Hag-Elsafi, A. Alampalli, and J. Kunin, “Application of FRP laminates for strengthening of a reinforced-concrete T-beam bridge structure,” Composite Structures, 52, No. 3-4, 453-466 (2001).

    Article  Google Scholar 

  3. N. F. Grace, G. A. Sayed, A. K. Soliman and K. R. Saleh, “Strengthening reinforced concrete beams using fiber reinforced polymer (FRP) laminates,” Structural Journal, 96, No. 5, 865-875 (1999).

    Google Scholar 

  4. H. R. Sobuz, E. Ahmed, S. Hasan, and A. Uddin, “Use of carbon fiber laminates for strengthening reinforced concrete beams in bending,” International Refereed Journal of Engineering and Science, 2, No. 1, 45-53 (2011).

    Google Scholar 

  5. S. T. Smith and J. G. Teng, “FRP strengthened RC beams I,” Engineering Structures, 24, No. 4, 385-395 (2002).

    Article  Google Scholar 

  6. Al. G. Chami, M. Theriault, and K. W. Neale, “Creep behaviour of CFRP-strengthened reinforced concrete beams,” Construction and Building Materials, 23, No. 4, 1640-1652 (2009).

    Article  Google Scholar 

  7. J. Valivonis, T. Skuturna, and M. Daugevičius, “The load-carrying capacity of reinforced concrete beams strengthened with carbon fiber composite in the tension zone subjected to temporary or ustained loading,” in: P. Vainiūnas and E. K. Zavadskas (eds.), The 10th International Conference “Modern Building Materials, Structures and Techniques”: Selected papers, Vol. 2, Vilnius: Technika, Lithuania, 818–825 (2010).

  8. B. Gao, C. K. Y. Leung, and J. K. Kim, “Failure diagrams of FRP strengthened RC beams,” Composite Structures, 77, No. 4, 493–508 (2007).

    Article  Google Scholar 

  9. A. R. Khaloo and A. Gharachorlou, “Numerical analysis of RC beams flexurally strengthened by CFRP laminates,” Iranian Journal of Civil Engineering, 3, No. 1, 1-9 (2005).

    Google Scholar 

  10. D. I. Kachlakevand and D. D. Mc Curry, Testing of full-size reinforced concrete beams strengthened with FRP composites: Experimental results and design methods verification, Final Report for Oregon Department of Transportation, Oregon (2000).

    Google Scholar 

  11. Y. T. Obaidat, Structural retrofitting of reinforced concrete beams using carbon fiber reinforced polymer, Licentiate Dissertation, Lund University, Lund (2010).

  12. N. P. Holmer, Par Study of the Bond Between Fiber Reinforced Polymers and Concrete using Finite Element Analysis, Master’s thesis, Marquette University, Milwaukee (2009).

  13. V. M. Karbhari, “Durability of FRP composites for civil infrastructure myth, mystery or reality,” Advances in Structural Engineering, 6, No. 3, 243-255 (2003).

    Article  Google Scholar 

  14. H. Thomsen, E. Spacone, S. Limkatanyu, and G. Camata, “Failure mode analyses of reinforced concrete beams strengthened in flexure with externally bonded fiber-reinforced polymers,” Journal of Composites for Construction, 8, No. 2, 123-131 (2004).

    Article  Google Scholar 

  15. A. M. Malek, H. Saadatmanesh, and M. R. Ehsani, “Prediction of failure Load of RC beams strengthened with FRP plate due to stress concentration at the plate end,” ACI Structural Journal, 95, No. 2, 142-152 (1998).

    Google Scholar 

  16. J. Casas and J. Pascual, “Debonding of FRP in bending: Simplified model and experimental validation,” Construction and Building Materials, 21, No. 10, 1940-1949 (2007).

    Article  Google Scholar 

  17. G. Yao and G. Teng, “Plate end debonding in FRP-plated RC beams I: Experiments,” Engineering Structures, 29, No. 10, 2457-2471 (2007).

    Article  Google Scholar 

  18. P. C. F. Da Silva Duarte, Reinforced concrete beams strengthened with CFRP laminates: an experimental study on the effect of crack repair, Instituto Superior Tecnico, Universidade Tecnica di Lisboa, Lisbon (2011).

    Google Scholar 

  19. Y. T. Obaidat, S. Heyden, O. Dahlblom, G. Abu-Farsakh, and Y. Abdel-Jawad, “Retrofitting of reinforced concrete beams using composite laminates,” Construction and Building Materials, 25, No. 2, 591-597 (2011).

    Article  Google Scholar 

  20. S. Lee and S. Moy, “Prediction of flexural strength of rc beams strengthened with carbon fibre reinforced polymer,” Science and Engineering of Composite Materials, 14, No. 3, 169-180 (2007).

    Article  Google Scholar 

  21. J. Sim, “Structural performance of concrete t-beam bridge strengthened with fiber reinforced plastics, CFS, GFRP and AFS,” Science and Engineering of Composite Materials, 13, No. 1, 1-12 (2006).

    CAS  Article  Google Scholar 

  22. G. Ramos, J. R. Casas, and A. Alarcón, “Normalized test for prediction of debonding failure in concrete elements strengthened with CFRP,” Journal of Composites for Construction, 10, No. 6, 509-519 (2006).

    CAS  Article  Google Scholar 

  23. R. Sen, M. Shahawy, G. Mullins, and J. Spain, “Durability of carbon fiber-reinforced polymer /epoxy/concrete bond in marine environment,” ACI Structural Journal, 96, No. 6, 906-914 (1999).

    Google Scholar 

  24. R. Kotynia, “Bond between FRP and concrete in reinforced concrete beams strengthened with near surface mounted and externally bonded reinforcement,” Construction and Building Materials, 32, No. 1, 41-54 (2011).

    Google Scholar 

  25. T. Shit, Experimental and numerical study on behavior of externally bonded RC T-beams using GFRP composites, Master’s thesis, National Institute of Technology, Orissa (2011).

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The authors would like to express their gratitude to the Engineering Chamber of Montenegro for the financial support and to the local construction company “Fidija” for donation of the strengthening material needed for this research.

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Correspondence to N. K. Vuković.

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Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 56, No. 1, pp. 109-122, January-February, 2020.

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Vuković, N.K., Jevrić, M. & Zejak, R. Experimental Analysis of RC Elements Strengthened with CFRP Strips. Mech Compos Mater 56, 75–84 (2020).

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  • composite T-beams
  • full-size beams
  • CFRP strips
  • flexural behavior
  • experiment
  • short-term load