Analysis of RC hollow columns strengthened with GFRP

Gian Piero Lignola, Fabio Nardone, Andrea Prota, Antonio De Luca, Antonio Nanni

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Reinforced concrete (RC) hollow piers in bridges withstand high moment and shear demands ensured with reduced mass and lower stress on foundations compared with solid piers. Failure of hollow columns is typically affected by premature buckling of reinforcing bars and concrete cover spalling. At present, no guidelines are available for the design of their upgrade, and few research investigations can be found on hollow columns strengthened by using fiber-reinforced polymer (FRP) materials. This paper discusses an experimental program carried out on purely compressed RC hollow columns externally wrapped with glass-fiber-reinforced polymer (GFRP). Three specimens were tested: one specimen was unstrengthened and used as the benchmark; the other two specimens were GFRP-wrapped with different confining reinforcement ratios. Each specimen was designed according to dated codes (i.e., prior to 1970) accounting only for gravity loads. In particular, steel longitudinal bars cross section and steel tie-spacing were designed with the minimum amount of longitudinal reinforcement and minimum tie area at maximum spacing. Tests results highlight that the GFRP-jacket mainly provided ductility increases before low strength increments could be obtained. Refined and simplified numerical models for hollow square RC columns, previously proposed by the authors, herein extend to hollow rectangular members. Comparisons of experimental results and theoretical predictions on the basis of both refined and simplified confinement models were performed and showed good agreement. In the case of the simplified model, a value for the effective ultimate FRP strain was suggested.

Original languageEnglish (US)
Pages (from-to)545-556
Number of pages12
JournalJournal of Composites for Construction
Issue number4
StatePublished - Jul 2011


  • Concrete columns
  • Confinement
  • Fiber reinforced polymer
  • Hollow sections
  • Modeling
  • Models
  • Wrapping

ASJC Scopus subject areas

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


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