Strength of circular hollow sections (CHS) tubular beams externally reinforced by carbon FRP sheets in pure bending

J. Haedir, M. R. Bambach, X. L. Zhao, R. H. Grzebieta

Research output: Journal article publicationJournal articleAcademic researchpeer-review

122 Citations (Scopus)


Particular structural forms such as circular tubular sections when under load may experience premature local buckling of the steel component, attributable to the thin-walled nature of the section. The use of high-strength advanced composite materials tends to accompany the minimum of structural weight, and is hence presently being assessed for effectiveness as supplementary external reinforcing materials. Composite beams of fibre-reinforced polymers (FRP) and steel, formed as tubular steel sections externally reinforced by thin-bonded carbon FRP (CFRP) sheets, exhibit many phenomena not found in conventional structural steel components, and these can have a marked bearing both on the behaviour of members composed of these materials and, by connotation, on the way in which such members are designed. The potential identification of CFRP reinforcement incorporated onto steel circular hollow section (CHS) beams has not been adequately explored, particularly in pure moment regions. This paper provides an experimental study consisting of CHS beams reinforced by CFRP sheets under pure bending. The role of the composite reinforcement is to interact with the enveloped steel component and to restrain the section to deform in a favourable fashion for strength enhancement. It is shown how these sections exploit the best attributes of both reinforcing fibres and steel, conferring greater strength to CHS beams made with thin-walled steel sections. The tests reveal that the strength of composite beams is influenced mainly by the amount of fibre reinforcement and the orientation of fibre skin. Also presented in this paper is an analytical method employing the modular ratio concept and considering the sectional slenderness limits of AS 4100 for evaluation of the strength of CFRP-reinforced CHS beams.

Original languageEnglish
Pages (from-to)1136-1147
Number of pages12
JournalThin-Walled Structures
Issue number10
Publication statusPublished - Oct 2009
Externally publishedYes


  • Carbon FRP sheets
  • CHS beams
  • Circumferentially reinforced
  • Local buckling
  • Pure bending
  • Strength

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Mechanical Engineering


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