Shear strength model for FRP-strengthened RC beams with adverse FRP-steel interaction

G. M. Chen, Jinguang Teng, J. F. Chen

Research output: Journal article publicationJournal articleAcademic researchpeer-review

78 Citations (Scopus)


RC beams shear strengthened with externally bonded fiber-reinforced polymer (FRP) U strips or side strips usually fail owing to debonding of the bonded FRP shear reinforcement. Because such debonding usually occurs in a brittle manner at relatively small shear crack widths, some of the internal steel stirrups intersected by the critical shear crack may not have reached yielding at beam shear failure. Consequently, the yield stress of internal steel stirrups in such a strengthened RC beam cannot be fully utilized. This adverse shear interaction between the internal steel shear reinforcement and the external FRP shear reinforcement may significantly reduce the benefit of the shear-strengthening FRP but has not been considered explicitly by any of the shear strength models in the existing design guidelines. This paper presents a new shear strength model considering this adverse shear interaction through the introduction of a shear interaction factor. A comprehensive evaluation of the proposed model, as well as three other shear strength models, is conducted using a large test database. It is shown that the proposed shear strength model performs the best among the models compared, and the performance of the other shear strength models can be significantly improved by including the proposed shear interaction factor. Finally, a design recommendation is presented.
Original languageEnglish
Pages (from-to)50-66
Number of pages17
JournalJournal of Composites for Construction
Issue number1
Publication statusPublished - 1 Feb 2013


  • Bonding
  • Concrete beams
  • Fiber-reinforced polymer
  • Reinforced concrete
  • Shear failures
  • Shear resistance
  • Shear strength

ASJC Scopus subject areas

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


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