Materials and Structures

, Volume 43, Issue 10, pp 1369–1381 | Cite as

Axial compressive behavior of concrete actively confined by metal strips; part A: experimental study

  • Hasan Moghaddam
  • Maysam Samadi
  • Kypros Pilakoutas
  • Saiid Mohebbi
Original Article


This paper presents the results of an experimental study on the application of strapping technique for retrofit of concrete compressive specimens. In this technique, standard strapping devices, which are used in the packaging industry, are applied to post-tension high strength metal strips around the concrete columns. Experimental program included axial compressive tests on 72 cylindrical and prismatic compressive specimens, which were actively confined by pre-stressed metal strips. The effects of various parameters on strength and ductility of confined concrete were studied including compressive strength of concrete, mechanical volumetric ratio of confining strips, post-tensioning force in the strip, number of strip layers wrapped around the specimens and details of strip joint. The effects of strength and ductility of confining strips on the behavior of confined specimens were also studied. Longitudinal and lateral strains of concrete and strain of the strips were monitored. Test results showed significant increase in the strength and ductility of specimens due to active confinement by metal strips. It was observed that ductility of confining material plays the most important role in enhancement of concrete ductility. The gain in strength is strongly dependent to the effective mechanical volumetric ratio of confining strips. It was also observed that the active confinement of concrete by post-tensioning the confining element results in stiffer pre-peak response of concrete specimens than the usual passive confinement.


Concrete Retrofitting Metal strips Active confinement Column 



The authors would like to thank BHRC for their kind supports.


  1. 1.
    Kent DC, Park R (1971) Flexural members with confined concrete. J Struct Eng 97(ST7):1969–1990Google Scholar
  2. 2.
    Mander JB, Priestley MJN, Park R (1988) Observed stress-strain behavior of confined concrete. J Struct Eng 114(8):1827–1849CrossRefGoogle Scholar
  3. 3.
    Dilger WH, Koch R, Kowalczyk R (1989) Ductility of confined concrete under different strain rates. ACI Struct J 81(1):73–84Google Scholar
  4. 4.
    Saatcioglu M, Ravzi SR (1992) Strength and ductility of confined concrete. J Struct Eng 118(6):1590–1607CrossRefGoogle Scholar
  5. 5.
    Saadatmanesh H (1994) Fibre composites for new and existing structures. ACI Struct J 91(3):346–354Google Scholar
  6. 6.
    Teran A, Ruiz J (1992) R/C jacketing of existing structures. In: Proceedings of the 10th world conference on earthquake engineering, SpainGoogle Scholar
  7. 7.
    Aboutaha RS, Engelhardt MD, Jirsa JO, Kreger ME (1996) Seismic retrofit of R/C columns using steel jackets. Published in seismic rehabilitation of concrete structures, ACI Special Publication No. SP-160, American Concrete Institute, pp 59–72Google Scholar
  8. 8.
    Mirmiran A, Shahawy M (1997) Behaviour of concrete columns confined by fibre composites. J Struct Eng 123(5):583–590CrossRefGoogle Scholar
  9. 9.
    Saatcioglu M, Yalcin C (2003) External prestressing concrete columns for improved seismic shear resistance. J Struct Eng 129(8):1057–1070CrossRefGoogle Scholar
  10. 10.
    Kazemi MT, Morshed R (2005) Seismic shear strengthening of R/C columns with ferrocement jacket. Cem Concr Compos 25(7):834–842Google Scholar
  11. 11.
    Frangou M, Pilakoutas K (1995) Structural repair/strengthening of RC columns. Constr Build Mater 9(5):259–266CrossRefGoogle Scholar
  12. 12.
    Moghaddam H, Samadi M (2009) On the effect of ductility of confining material on concrete ductility. In: Proceedings of the structural engineering congress, ASCE/SEI, Austin, Texas, USAGoogle Scholar

Copyright information

© RILEM 2010

Authors and Affiliations

  • Hasan Moghaddam
    • 1
  • Maysam Samadi
    • 1
  • Kypros Pilakoutas
    • 2
  • Saiid Mohebbi
    • 1
  1. 1.Department of Civil EngineeringSharif University of TechnologyTehranIran
  2. 2.Department of Civil and Structural EngineeringUniversity of SheffieldSheffieldUK

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