Title:
Behavior of Exterior Beam-Column Connections with Headed Bars under Nonreversible Cyclic Loading
Author(s):
Gustavo J. Parra-Montesinos and Jacob Zeuske
Publication:
Structural Journal
Volume:
122
Issue:
5
Appears on pages(s):
71-81
Keywords:
anchorage; bar groups; breakout strength; development length; joints; shear
DOI:
10.14359/51746793
Date:
9/1/2025
Abstract:
Two large-scale exterior beam-column connections with beam longitudinal headed bars were tested to evaluate their susceptibility to breakout failures. The specimens were designed following the strength and transverse reinforcement detailing provisions in Chapter 15 of ACI 318-19. The variable investigated was the headed bar embedment length, which was determined based on either Chapter 25 of ACI 318-19 or recent research at The University of Kansas, the latter leading to a 22% shorter embedment length. Both specimens exhibited beam flexural yielding, but the specimen with the shorter bar embedment length experienced significantly more connection damage, followed by a concrete breakout failure. Based on the limited test results, it is recommended that nominal joint shear strength be calculated based on a joint effective depth equal to the headed bar embedment length and a shear stress of
1.0λ√fc' MPa (12λ√fc' psi). A method for calculating headed bar group anchorage strength in exterior beam-column connections was proposed, which led to reasonable and conservative strength estimates in the test specimens.
Related References:
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ASTM C39/C39M-21, 2021, “Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens,” ASTM International, West Conshohocken, PA, 8 pp.
Banaeipour, A.; Darwin, D.; O’Reilly, M.; Lequesne, R. D.; Lepage, A.; and Blessent, M., 2023, “Development of Large High-Strength Reinforcing Bars with Standard Hooks and Heads,” SM Report No. 153, The University of Kansas Center for Research, Inc., Lawrence, KS, July 2023, 428 pp.
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