Local bond–slip model for plain surface reinforcement

John Cairns*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)
63 Downloads (Pure)


Nowadays virtually all-concrete construction uses reinforcement with deformations rolled or indented on the bar surface to improve bond between bar and concrete, but many older structures built with plain surface bars remain in service. The increasing need for assessment of existing construction means there is a continuing need for information on their performance. Research into plain surface bars essentially ceased when ribbed bars became established, and plain bars have consequently been bypassed in developments in understanding and modeling of bond since 1960. The profession's ability to numerically model behavior of concrete structures has expanded dramatically since plain surface reinforcement was discontinued. The option of numerically modeling may be particularly important for assessment of existing structures with noncompliant details. Although the fib Model Code 2010 includes a local bond–slip model for plain surface bars, information on the derivation of the model and supporting evidence of its validation are not available. The current paper analyses data on bond–slip behavior of plain surface bars and demonstrates shortcomings in the fib model. An improved model is proposed and verified against test data from an independent source.

Original languageEnglish
Pages (from-to)666-675
Number of pages10
JournalStructural Concrete
Issue number2
Early online date7 Aug 2020
Publication statusPublished - Apr 2021


  • anchorage
  • assessment
  • bond slip
  • local bond
  • plain bars

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • General Materials Science
  • Mechanics of Materials


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