Shear-reinforced concrete breakout design methodology for moment transfer at column-foundation connections

Benjamin L. Worsfold, Jack P. Moehle

Research output: Contribution to journalArticlepeer-review


Recent studies have shown that the strength of column-foundation connections carrying moment can be limited by the concrete breakout failure mode. Distributed shear reinforcement in the concrete breakout cone region has been observed to increase the strength and displacement capacity of structural connections governed by breakout. However, the ACI 318–19 building code does not allow designers to consider this strength increase. Rather, the code allows the use of anchor reinforcement provided that the concrete contribution to strength is ignored. This paper proposes a design methodology to calculate the breakout strength considering the additive effect of concrete and reinforcement. Physical test data and finite element simulations from previous studies were used to calibrate the proposed strength equations. Detailing requirements are discussed.

Original languageEnglish (US)
Article number115783
JournalEngineering Structures
StatePublished - May 15 2023
Externally publishedYes

Bibliographical note

Funding Information:
The authors express their gratitude to the ACI Foundation Concrete Research Council, the American Institute of Steel Construction (AISC), and the Hilti Corporation for financing this and other ongoing research projects at UC Berkeley relating to concrete anchorage. This study was greatly improved through discussions with the following individuals: Rafael Sabelli (director of seismic design at Walter P. Moore), James Malley (senior principal of Degenkolb Engineers), John Silva (senior director of codes and standards for Hilti North America), and Roberto Piccinin (VP for code development and research for Hilti).

Publisher Copyright:
© 2023 Elsevier Ltd


  • Anchor reinforcement
  • Anchoring to concrete
  • Breakout
  • Column-foundation connection
  • Finite element modeling
  • Shear reinforcement
  • Supplementary reinforcement


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