Title:
Development of Large High-Strength Headed Reinforcing Bars
Author(s):
Ali Banaeipour, David Darwin, Matthew O’Reilly, and Andres Lepage
Publication:
Structural Journal
Volume:
122
Issue:
3
Appears on pages(s):
187-199
Keywords:
anchorage; beam-column joint; bond, development length; headed bar; high-strength concrete; high-strength steel; large-scale testing
DOI:
10.14359/51744381
Date:
5/1/2025
Abstract:
The ACI 318-19 Building Code does not allow the use of headed
bars larger than No. 11 (No. 36) due to insufficient experimental
data. Thirty large-scale simulated beam-column joint specimens
containing high-strength No. 11 (No. 36), No. 14 (No. 43), or
No. 18 (No. 57) headed bars were tested to investigate the effects
on anchorage strength of key factors, including bar stress at failure,
bar size, bar spacing, embedment length, transverse reinforcement,
concrete compressive strength, and loading condition. Specimens
exhibited concrete breakout, side splitting, or a combination, with
four exhibiting a shear-like failure. Anchorage of larger bars is
noticeably influenced by joint shear demand and loading condition.
Descriptive equations developed based on 164 tests accurately
characterize anchorage strength for headed bars up to No. 18
(No. 57). They indicate that anchorage strength is proportional to
concrete compressive strength to a power close to 0.2 and that the
contribution of parallel ties for large headed bars is lower than that
observed for smaller headed bars.
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