A theoretical model to predict interface slip due to bending

Ourania Tsioulou, Stephanos E. Dritsos

Research output: Contribution to journalArticlepeer-review


Casting a new concrete layer on the tensile or compressive side of a reinforced concrete element is a common technique that is used to increase the flexural capacity of weak reinforced concrete elements. Until now however, a model has not been presented in the literature to evaluate the slip between the two components. Usually, in common practical design, slip is ignored and the strengthened element is assumed monolithic. This may not be a conservative assumption, as any slip would affect the ultimate resistance of the strengthened element. In the present paper, an analytical procedure is presented that predicts the distribution of slip strain, slip and shear stress along a reinforced or unreinforced interface between an initial beam and a new concrete layer. By following this process, the capacity of a strengthened beam is determined by taken slip into account. In addition, a step-by-step design procedure is presented and then applied to an experimental result. Good agreement if found. Further verification of the analytical procedure is performed by comparison with finite element analysis and very good agreement is found.
Original languageEnglish
Pages (from-to)825-843
Number of pages19
JournalMaterials and Structures
Issue number4
Publication statusPublished - 31 May 2011


  • Strengthening
  • Concrete beams
  • Concrete layers
  • Interface
  • Shear stress
  • Slip strain
  • Slip


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