Title:
Conventional and High-Strength Headed Bars—Part 1: Anchorage Tests
Author(s):
Krishna P. Ghimire, Yun Shao, David Darwin, and Matthew O’Reilly
Publication:
Structural Journal
Volume:
116
Issue:
3
Appears on pages(s):
255-264
Keywords:
anchorage; beam-column joints; bond and development; development length; headed bars; high-strength concrete; high-strength steel; reinforcement
DOI:
10.14359/51714479
Date:
5/1/2019
Abstract:
Results of an experimental program on the anchorage strength of headed reinforcing bars are presented. Two hundred and two exterior beam-column joint specimens with concrete compressive strengths ranging from 3960 to 16,030 psi (27.3 to 110.6 MPa) were tested under monotonic loading. Key parameters included concrete compressive strength, embedment length, bar size, head size, spacing between headed bars, and confining reinforcement within the joint region. Bar stresses at failure ranged from 26,100 to 153,200 psi (180 to 1057 MPa). Specimens exhibited concrete breakout, side-face blowout, or a combination of the two failure modes, with concrete breakout being the dominant failure mode. A comparison of bar stress at anchorage failure with the stress calculated based on ACI 318-14 shows that ACI 318-14 provides a very conservative estimate of anchorage strength for No. 5 (No. 16) bars and low concrete compressive strengths. The estimate becomes progressively less conservative with increasing bar size and concrete compressive strength.
Related References:
ACI Committee 318, 2014, “Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14),” American Concrete Institute, Farmington Hills, MI, 520 pp.
ACI Committee 408, 2003, “Bond and Development of Straight Reinforcement in Tension (ACI 408R-03),” American Concrete Institute, Farmington Hills, MI, 49 pp.
ASTM A1035/A1035M-15, 2015, “Standard Specification for Deformed and Plain, Low-Carbon, Chromium, Steel Bars for Concrete Reinforcement,” ASTM International, West Conshohocken, PA, 7 pp.
ASTM A615/A615M-14, 2014, “Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement,” ASTM International, West Conshohocken, PA, 7 pp.
ASTM A706/A706M-15, 2015, “Standard Specification for Deformed and Plain Low-Alloy Steel Bars for Concrete Reinforcement,” ASTM International, West Conshohocken, PA, 7 pp.
ASTM A970/A970M-13a, 2013, “Standard Specification for Headed Steel Bars for Concrete Reinforcement,” ASTM International, West Conshohocken, PA, 9 pp.
ASTM A970/A970M-18, 2018, “Standard Specification for Headed Steel Bars for Concrete Reinforcement,” ASTM International, West Conshohocken, PA, 10 pp.
Draper, N. R., and Smith, H., 1981, Applied Regression Analysis, second edition, John Wiley and Sons, Wiley, New York, 241-249 pp.
Ghimire, K. P.; Darwin, D.; and O’Reilly, M., 2018, “Anchorage of Headed Reinforcing Bars in Concrete,” SM Report No. 127, University of Kansas Center for Research, Lawrence, KS, Jan., 278 pp.
Marques, J. L., and Jirsa, J. O., 1975, “A Study of Hooked Bar Anchorages in Beam-Column Joints,” ACI Journal Proceedings, V. 72, No. 5, May, pp. 198-209.
Shao, Y.; Darwin, D.; O’Reilly, M.; Lequesne, R. D.; Ghimire, K.; and Hano, M., 2016, “Anchorage of Conventional and High-Strength Headed Reinforcing Bars,” SM Report No. 117, University of Kansas Center for Research, Lawrence, KS, Aug., 334 pp.
Sperry, J.; Yasso, S.; Searle, N.; DeRubeis, M.; Darwin, D.; O’Reilly, M.; Matamoros, A.; Feldman, L.; Lepage, A.; and Lequesne, R., 2017, “Conventional and High-Strength Hooked Bars—Part 1: Anchorage Tests,” ACI Structural Journal, V. 114, No. 1, Jan.-Feb., pp. 255-266. doi: 10.14359/51689457