Title:
Effect of Beam Depth on Anchorage Strength of Hooked and Headed Bars
Author(s):
Zachary Coleman, Eric Jacques, and Carin Roberts-Wollmann
Publication:
Structural Journal
Volume:
120
Issue:
3
Appears on pages(s):
197-206
Keywords:
anchorage; beam-column joints; bond and development; effective beam depth; headed bars; hooked bars; lever-arm distance; strut angle
DOI:
10.14359/51738510
Date:
5/1/2023
Abstract:
Several studies have reported that the flexural lever-arm distance can influence the anchorage strength of hooked and headed bars. However, this so-called “beam-depth effect” is not reflected in design practice because it has not been sufficiently studied. The objective of this paper is to evaluate the influence of the lever-arm distance on anchorage strength. A database of 445 anchorage tests of hooked bars was assembled. Increases in the effective beam depth were found to correlate with decreases in the anchorage strength of hooked bars. Multivariable regression analyses were used to develop descriptive equations for the anchorage strength of hooked
bars considering various parameters, including the effective beam depth. A modification factor accounting for the beam-depth effect was proposed for the ACI 318-19 equation for the development length of hooked bars. Preliminary analyses suggested that a similar beam-depth effect may exist for headed bars.
Related References:
ACI Committee 318, 2019, “Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary (ACI 318R-19) (Reapproved 2022),” American Concrete Institute, Farmington Hills, MI, 624 pp.
ACI CT-21, 2021, “ACI Concrete Terminology,” American Concrete Institute, Farmington Hills, MI, 76 pp.
Ajaam, A.; Yasso, S.; Darwin, D.; O’Reilly, M.; and Sperry, J., 2018, “Anchorage Strength of Closely Spaced Hooked Bars,” ACI Structural Journal, V. 115, No. 4, July, pp. 1143-1152. doi: 10.14359/51702065
ASTM A970/A970M-18, 2018, “Standard Specification for Headed Steel Bars for Concrete Reinforcement,” ASTM International, West Conshohocken, PA, 10 pp.
Bashandy, T. R., 1996, “Application of Headed Bars in Concrete Members,” PhD dissertation, The University of Texas at Austin, Austin, TX, 318 pp.
Chun, S.; Bae, M.-S.; and Lee, B.-S., 2017, “Side-Face Blowout Strength of 43 and 57 mm (No. 14 and No. 18) Hooked Bars in Beam-Column Joints,” ACI Structural Journal, V. 114, No. 5, Sept.-Oct., pp. 1227-1238. doi: 10.14359/51700804
Chun, S.-C.; Oh, B.; Lee, S.-H.; and Naito, C. J., 2009, “Anchorage Strength and Behavior of Headed Bars in Exterior Beam-Column Joints,” ACI Structural Journal, V. 106, No. 5, Sept.-Oct., pp. 579-590.
Darwin, D.; Dolan, C. W.; and Nilson, A. H., 2016, Design of Concrete Structures, 15th edition, McGraw-Hill Education, New York, NY, 801 pp.
Eligehausen, R.; Mallée, R.; and Silva, J. F., 2006, Anchorage in Concrete Construction, first edition, Ernst & Sohn, Berlin, Germany, 391 pp.
Ghimire, K. P.; Shao, Y.; Darwin, D.; and O’Reilly, M., 2019, “Conventional and High-Strength Headed Bars—Part 2: Data Analysis,” ACI Structural Journal, V. 116, No. 3, May, pp. 265-272. doi: 10.14359/51714480
Hamad, B. S.; Jirsa, J. O.; and D’Abreu de Paulo, N. I., 1993, “Anchorage Strength of Epoxy-Coated Hooked Bars,” ACI Structural Journal, V. 90, No. 2, Mar.-Apr., pp. 210-217.
Hwang, H.-J.; Park, H.-G.; and Yi, W.-J., 2017, “Development Length of Standard Hooked Bar Based on Non-Uniform Bond Stress Distribution,” ACI Structural Journal, V. 114, No. 6, Nov.-Dec., pp. 1637-1648. doi: 10.14359/51700918
Johnson, L. A., and Jirsa, J. O., 1981, “The Influence of Short Embedment and Close Spacing on the Strength of Hooked Bar Anchorages,” PMFSEL Report No. 81-2, The University of Texas at Austin, Austin, TX, 104 pp.
Joint ACI-ASCE Committee 408, 2003, “Bond and Development of Straight Reinforcing Bars in Tension (ACI 408R-03) (Reapproved 2012),” American Concrete Institute, Farmington Hills, MI, 49 pp.
Marques, J. L. G., 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.
Pinc, R. L.; Watkins, M. D.; and Jirsa, J. O., 1977, “Strength of Hooked Bar Anchorages in Beam-Column Joints,” CESRL Report No. 77-3, The University of Texas at Austin, Austin, TX, 80 pp.
Ramirez, J. A., and Russell, B. W., 2008, “Transfer, Development, and Splice Length for Strand/Reinforcement in High-Strength Concrete,” NCHRP Report 603, Transportation Research Board, Washington, DC, 122 pp.
Shao, Y.; Darwin, D.; O’Reilly, M.; Lequesne, R.; Ghimire, K.; and Hano, M., 2016, “Anchorage of Conventional and High-Strength Headed Reinforcing Bars,” SM Report No. 117, The University of Kansas Center for Research, Inc., Lawrence, KS, 366 pp.
Sperry, J.; Al-Yasso, S.; Searle, N.; DeRubeis, M.; Darwin, D.; O’Reilly, M.; Matamoros, A.; Feldman, L.; Lepage, A.; Lequesne, R.; and Ajaam, A., 2015, “Anchorage of High-Strength Reinforcing Bars with Standard Hooks,” SM Report No. 111, The University of Kansas Center for Research, Inc., Lawrence, KS, 266 pp.
Sperry, J.; Darwin, D.; O’Reilly, M.; Lequesne, R. D.; Yasso, S.; Matamoros, A.; Feldman, L. R.; and Lepage, A., 2017b, “Conventional and High-Strength Hooked Bars–Part 2: Data Analysis,” ACI Structural Journal, V. 114, No. 1, Jan.-Feb., pp. 267-276. doi: 10.14359/51689457
Sperry, J.; Yasso, S.; Searle, N.; DeRubeis, M.; Darwin, D.; O’Reilly, M.; Matamoros, A.; Feldman, L. R.; Lepage, A.; Lequesne, R. D.; and Ajaam, A., 2017a, “Conventional and High-Strength Hooked Bars–Part 1: Anchorage Tests,” ACI Structural Journal, V. 114, No. 1, Jan.-Feb., pp. 255-265. doi: 10.14359/51689457