Bar buckling in RC columns confined with composite materials

D. A. Bournas, T. C. Triantafillou

Research output: Contribution to journalArticlepeer-review


The onset and evolution of bar buckling at the plastic hinge of old-type reinforced concrete (RC) columns confined with composite material [fiber-reinforced polymer (FRP) and textile-reinforced mortar (TRM)] jackets was investigated experimentally and analytically in this study. The interaction between composite jacket (or concrete cover, for unconfined concrete) and embedded longitudinal compression reinforcement at the onset and evolution of bar buckling was achieved through strain measurements of the compression reinforcement. Moreover, the implementation of a recent stress-strain confinement model, which relates lateral with axial strains, allowed the description and monitoring of the axial-lateral strain relationship at the base of the columns throughout the evolution of bar buckling. Based on the aforementioned model and the experimental measurements, the postbuckling behavior of columns was related to the jacket stiffness. Finally, a semiempirical expression that gives the drift ratio of RC columns at the onset of bar buckling was modified herein for the case of FRP- or TRM-jacketed columns.

Original languageEnglish (US)
Pages (from-to)393-403
Number of pages11
JournalJournal of Composites for Construction
Issue number3
StatePublished - May 2011


  • Bar buckling
  • Confinement
  • FRP
  • Reinforced concrete
  • Seismic retrofitting
  • Textile-reinforced mortar (TRM)

ASJC Scopus subject areas

  • Ceramics and Composites
  • Civil and Structural Engineering
  • Building and Construction
  • Mechanics of Materials
  • Mechanical Engineering


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