concrete structures; deep beams; shear; headed reinforcement; hooks
Abstract :
[en] While anchor heads are particularly useful in the case of large bars which require significant development lengths, the ACI code provides design guidance for bars #11 or smaller. This paper presents a test of a large deep beam reinforced with a single #18 headed bar. The behavior of the beam is evaluated in comparison to the behavior of a specimen with more conventional reinforcement of 6#8 headed bars, and to the behavior of a specimen with lap-spliced anchor hooks. Despite the extreme detailing of the specimen with a single #18 bar, the beam had the same strength as the specimen with 6#8 bars. The compressive stress in front of the anchor head reached about 1.5 times the compressive strength of the concrete and the stress in the #18 bar reached about 414 MPa (60 ksi) before the beam failed in shear along a diagonal crack away from the anchorage zone. Shear strength calculations according to Appendix A of the ACI code showed that the current strut-and-tie provisions can overestimate the shear strength of deep beams by as much as 23%.
Disciplines :
Civil engineering
Author, co-author :
Mihaylov, Boyan ; Université de Liège - ULiège > Département Argenco : Secteur SE > Structures en béton
ACI Committee on Standard Building Regulations for the Use of Reinforced Concrete, "Standard Building Regulations for the Use of Reinforced Concrete, " ACI Journal, V. 16, No. 2, Feb. 1920, pp. 283-302.
Dilger, W. H., and Ghali, A., "Shear Reinforcement for Concrete Slabs, " ASCE Proceedings, V. 107, No. ST12, 1981, pp. 2403-2420.
Berner, D. E.; Gerwick, B. C.; and Hoff, G. C., "T-Headed Stirrup Bars, " Concrete International, V. 13, No. 5, May 1991, pp. 49-53.
ACI Committee 318, "Building Code Requirements for Structural Concrete (ACI 318-11) and Commentary, " American Concrete Institute, Farmington Hills, MI, 2011, 503 pp.
Thompson, M. K.; Ziehl, M. J.; Jirsa, J. O.; and Breen, J. E., "CCT Nodes Anchored by Headed Bars-Part 1: Behavior of Nodes, " ACI Structural Journal, V. 102, No. 6, Nov.-Dec. 2005, pp. 808-815.
Thompson, M. K.; Jirsa, J. O.; and Breen, J. E., "CCT Nodes Anchored by Headed Bars-Part 2: Capacity of Nodes, " ACI Structural Journal, V. 103, No. 1, Jan.-Feb. 2006, pp. 65-73.
Thompson, M. K.; Ledesma, A.; Jirsa, J. O.; and Breen, J. E., "Lap Splices Anchored by Headed Bars-Part 1: Behavior of Nodes, " ACI Structural Journal, V. 103, No. 2, Mar.-Apr. 2006, pp. 271-279.
Thompson, M. K.; Jirsa, J. O.; and Breen, J. E., "Behavior and Capacity of Headed Reinforcement, " ACI Structural Journal, V. 103, No. 4, July- Aug. 2006, pp. 522-530.
Sritharan, S.; Ingham, J.; Priestley, M.; and Seible, F., "Design and Performance of Bridge Cap Beam/Column Using Headed Reinforcement and Mechanical Couplers, " Developments of Seismic Steel Reinforcement Products & Systems, SP-184, R. H. Reiterman, ed., American Concrete Institute, Farmington Hills, MI, 1999, pp. 7-22.
Naito, C. J.; Moehle, J. P.; and Mosalam, K. M., "Evaluation of Bridge Beam-Column Joints under Simulated Seismic Loading, " ACI Structural Journal, V. 99, No. 1, Jan.-Feb. 2002, pp. 62-71.
Chun, S.-C.; Oh, B.; Lee, S.-H.; and Naito, C. J., "Anchorage Strength and Behavior of Headed Bars in Exterior Beam-Column Joints, " ACI Structural Journal, V. 106, No. 5, Sept.-Oct. 2009, pp. 579-590.
Mobeen, S. S.; Elwi, A. E.; and Ghali, A., "Double-Headed Studs in Shear Walls, " Concrete International, V. 27, No. 3, Mar. 2005, pp. 59-63.
Elgabry, A., and Ghali, A., "Design of Stud-Shear Reinforcement for Slabs, " ACI Structural Journal, V. 87, No. 3, May-June 1990, pp. 350-361.
Birkle, G., and Dilger, W. H., "Shear Strength of Slabs with Double- Headed Shear Studs in Radial and Orthogonal Layouts, " Thomas T.C. Hsu Symposium: Shear and Torsion in Concrete Structures, SP-265, A. Belarbi, Y.-L. Mo, and A. S. Ayoub, eds., American Concrete Institute, Farmington Hills, MI, 2009, pp. 499-510. (CD-ROM).
Commission of Inquiry into the Collapse of a Portion of the de la Concorde Overpass, Report, Oct. 3, 2006-Oct. 15, 2007, 198 pp.
Mihaylov, B. I.; Bentz, E. C.; and Collins, M. P., "Behavior of Large Deep Beam Subjected to Monotonic and Reversed Cyclic Shear, " ACI Structural Journal, V. 107, No. 6, Nov.-Dec. 2010, pp. 726-734.
Mihaylov, B. I., "Behavior of Deep Reinforced Concrete Beams under Monotonic and Reversed Cyclic Load, " doctoral thesis, European School for Advanced Studies in Reduction of Seismic Risk, Pavia, Italy, 2008, 379 pp.
Ghali, A., and Gayed, R. B., "Bundling of Headed Bars in Concrete, " Canadian Journal of Civil Engineering Note, V. 39, No. 7, 2012, pp. 849-853.
