Title:
Conventional and High-Strength Hooked Bars—Part 1: Anchorage Tests
Author(s):
J. Sperry, S. Yasso, N. Searle, M. DeRubeis, D. Darwin, M. O’Reilly, A. Matamoros, L. R. Feldman, A. Lepage, R. D. Lequesne, and A. Ajaam
Publication:
Structural Journal
Volume:
114
Issue:
1
Appears on pages(s):
255-265
Keywords:
anchorage; beam-column joints; bond and development; highstrength concrete; high-strength steel; hooks; reinforced concrete; reinforcement
DOI:
10.14359/51689456
Date:
1/1/2017
Abstract:
This paper presents the results of an experimental study on the anchorage strength of conventional and high-strength steel hooked bars. Three hundred and thirty-seven exterior beam-column joint specimens were tested with compressive strengths ranging from 4300 to 16,500 psi (30 to 114 MPa). Parameters investigated included the number of hooked bars per specimen, bar diameter, side cover, amount of confining reinforcement, hooked bar spacing, hook bend angle, hook placement, and embedment length. Bar stresses at failure ranged from 22,800 to 144,100 psi (157 and 994 MPa). The majority of the hooked bars failed by a combination of front and side failure, with front failure being the dominant failure mode. Test results show that development lengths of hooked bars calculated based on ACI 318-14 are very conservative for No. 5 (No. 16) bars and become progressively less conservative with increasing bar size and concrete compressive strength.
Related References:
AASHTO, 2012, “AASHTO LRFD Bridge Design Specifications,” sixth edition, American Association of State Highway and Transportation Officials, Washington DC, 1672 pp.
ACI Committee 318, 2014, “Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14), American Concrete Institute, Farmington Hills, MI, 519 pp.
ACI Committee 349, 2006, “Code Requirements for Nuclear Safety Related Concrete Structures (ACI 349-06),” American Concrete Institute, Farmington Hills, MI, 157 pp.
ACI Committee 408, 2003, “Bond and Development of Straight Reinforcing Bars in Tension (ACI 408R-03),” American Concrete Institute, Farmington Hills, MI, 49 pp.
ASTM A615/A615M-15, 2015, “Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement,” ASTM International, West Conshohocken, PA, 8 pp.
ASTM A1035/A1035M-14, 2014, “Standard Specification for Deformed and Plain Low-Carbon, Chromium, Steel Bars for Concrete Reinforcement,” ASTM International, West Conshohocken, PA, 7 pp.
ASTM C39/C39M-15a, 2015, “Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens,” ASTM International, West Conshohocken, PA, 7 pp.
Draper, N. R., and Smith, H., 1981, Applied Regression Analysis, second edition, Wiley, New York, 709 pp.
Hamad, B. S.; Jirsa, J. O.; and D’Abreu de Paulo, N. I., 1993, “Effect of Epoxy Coating on Bond Anchorage of Reinforcing in Concrete Structures,” ACI Structural Journal, V. 90, No. 1, Jan.-Feb., pp. 77-88.
Lee, J., and Park, H., 2010, “Bending – Applicability Study of Ultra-Bar (SD 600) and Ultra-Bar for Rebar Stirrups and Ties (SD 500 and 600) for Compression Rebar,” KCI-R-10-006 Report, Korea Concrete Institute, Seoul, South Korea, Aug., 504 pp. (translated from Korean)
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.
Minor, J., and Jirsa, J. O., 1975, “Behavior of Bent Bar Anchorages,” ACI Journal Proceedings, V. 72, No. 4, Apr., pp. 141-149.
Peckover, J., and Darwin, D., 2013, “Anchorage of High-Strength Reinforcing Bars with Standard Hooks: Initial Tests” SL Report No. 13-1, University of Kansas Center for Research, Lawrence, KS, 47 pp.
Pinc, R.; Watkins, M.; and Jirsa, J. O., 1977, “The Strength of the Hooked Bar Anchorages in Beam-Column Joints,” CESRL Report No. 77-3, Department of Civil Engineering-Structures Research Laboratory, University of Texas at Austin, Austin, TX, 67 pp.
Ramirez, J. A., and Russell, B. W., 2008, “Transfer, Development, and Splice Length for Strand/Reinforcement in High-strength Concrete,” NCHRP Report 603, National Cooperative Highway Research Program, Transportation Research Board, Washington, DC, 122 pp.
Searle, N.; DeRubeis, M.; Darwin, D.; Matamoros, A.; O’Reilly, M.; and Feldman, L., 2014, “Anchorage of High-Strength Reinforcing Bars with Standard Hooks – Initial Tests,” SM Report No. 108, University of Kansas Center for Research, Lawrence, KS, Feb., 110 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., 2015a, “Anchorage of High-Strength Reinforcing Bars with Standard Hooks,” SM Report No. 111, University of Kansas Center for Research, Lawrence, KS, June, 243 pp.
Sperry, J.; Darwin, D.; O’Reilly, M.; and Lequesne, R., 2015b, “Anchorage Strength of Conventional and High-Strength Hooked Bars in Concrete,” SM Report No. 115, University of Kansas Center for Research, Lawrence, KS, Dec., 266 pp.