Title:
Shear Strength of Post-Tensioned Slab-Column Connections: Reevaluation of ACI 318-19 Code
Author(s):
Giwan Noh and Thomas H.-K. Kang
Publication:
Structural Journal
Volume:
121
Issue:
4
Appears on pages(s):
197-212
Keywords:
flat plate; post-tensioned (PT); prestressed; punching; shear strength; slab-column connection
DOI:
10.14359/51740575
Date:
7/1/2024
Abstract:
Compared to conventional reinforced concrete (RC) flat-plate
systems, post-tensioned (PT) flat-plate systems lack experimental
studies on shear strength, and there are no studies that have been
analyzed and collected with clear criteria (for example, calculation
of effective depth, unbalanced moment, and measured shear
strength) about experiments conducted so far. As a result, the
current ACI 318-19, Section 22.6.5, for prestressed members has
many restrictions based on the lack of experimental data on the
nominal shear-strength equation. In this study, to reevaluate the
nominal shear strength of the PT flat-plate system more reasonably
and provide a reference for future studies, a total of 120 experimental data on the shear strength of the PT flat-plate system
without shear reinforcement that have been conducted so far were
recalculated and recompiled with clear criteria (the experimental
data consists of 74 interior connections, 41 edge connections,
and five corner connections). In addition, the factors affecting
the shear strength and the validity of restrictions in the nominal
shear-strength equation of ACI 318-19 were analyzed. The factors
affecting the shear strength include: 1) method of loading; 2) presence of nonprestressed reinforcement; and 3) reinforcement ratio along the lateral load direction. The restrictions in the nominal
shear-strength equation of ACI 318-19 include: 1) fc′ ≤ 4900 psi
(34 MPa); 2) fpc ≥ 125 psi (0.9 MPa) (in each direction); 3) fpc ≤
500 psi (3.5 MPa) (average in the two directions); and 4) it is
applicable only for interior connections.
Related References:
ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary (ACI 318R-19) (Reapproved 2022),” American Concrete Institute, Farmington Hills, MI, 2019, 624 pp.
Barbán, V. V., 2008, “Punching Shear in Unbonded Post-Tensioned Concrete Flat Slabs and Edge Columns,” PhD dissertation, University of Brasília, Brasília, Brazil.
Barbán, V. V.; Melo, G. S.; and Carvalho, A. L., 2020, “Punching Shear Tests of Post-Tensioned Flat Slabs Supported on Edge Columns,” Structural Concrete, V. 21, No. 1, pp. 247-261. doi: 10.1002/suco.201900160
Carvalho, A. L.; Melo, G. S.; Gomes, R. B.; and Regan, P. E., 2011, “Punching Shear in Post-Tensioned Flat Slabs with Stud Rail Shear Reinforcement,” ACI Structural Journal, V. 108, No. 5, Sept.-Oct., pp. 523-531. doi: 10.14359/51683209
Corrêa, G. S., 2001, “Puncionamento em Lajes Cogumelo Protendidas com Cabos Não Aderentes,” MS thesis, University of Brasília, Brasília, Brazil.
Foutch, D. A.; Gamble, W. L.; and Sunidja, H., 1990, “Tests of Post-
Tensioned Concrete Slab-Edge Column Connections,” ACI Structural Journal, V. 87, No. 2, Mar.-Apr., pp. 167-179. doi: 10.14359/2689
Gardner, N. J., and Kallage, M. R., 1998, “Punching Shear Strength of Continuous Post-Tensioned Concrete Flat Plates,” ACI Materials Journal, V. 95, No. 3, May-June, pp. 272-282. doi: 10.14359/371
Gerber, L. L., and Burns, N. H., 1971, “Ultimate Strength Tests of Post-Tensioned Flat Plates,” PCI Journal, V. 16, No. 6, pp. 40-58. doi: 10.15554/pcij.11011971.40.58
Grow, J. B., and Vanderbilt, M. D., 1967, “Shear Strength of Prestressed Lightweight Aggregate Concrete Flat Plates,” PCI Journal, V. 12, No. 4, pp. 18-28. doi: 10.15554/pcij.08011967.18.28
Han, S. W.; Kee, S.-H.; Park, Y.-M.; Lee, L.-H.; and Kang, T. H.-K., 2006a, “Hysteretic Behavior of Exterior Post-Tensioned Flat Plate Connections,” Engineering Structures, V. 28, No. 14, pp. 1983-1996. doi: 10.1016/j.engstruct.2006.03.029
Han, S. W.; Kee, S.-H.; Kang, T. H.-K.; Ha, S.-S.; Wallace, J. W.; and Lee, L.-H., 2006b, “Cyclic Behavior of Interior Post-Tensioned Flat Plate Connections,” Magazine of Concrete Research, V. 58, No. 10, pp. 699-711. doi: 10.1680/macr.2006.58.10.699
Han, S. W.; Kee, S.-H.; Park, Y.-M.; Ha, S.-S.; and Wallace, J. W., 2009, “Effects of Bottom Reinforcement on Hysteretic Behavior of Post-Tensioned Flat Plate Connections,” Journal of Structural Engineering, ASCE, V. 135, No. 9, pp. 1019-1033. doi: 10.1061/(ASCE)0733-9445(2009)135:9(1019)
Hassanzadeh, G., 1998, “Betongplattor på Pelare: Dimensioneringsmetoder för Plattor Med Icke Vidhäftande Spännarmering,” Trita-BKN Bulletin 43, KTH Royal Institute of Technology, Stockholm, Sweden, 160 pp.
Hawkins, N. M., 1981, “Lateral Load Resistance of Unbonded Post-
Tensioned Flat Plate Construction,” PCI Journal, V. 26, No. 1, pp. 94-117. doi: 10.15554/pcij.01011981.94.117
Hawkins, N. M.; Wong, C. F.; and Yang, C. H., 1978, “Slab-Edge Column Connections Transferring High Intensity Reversing Moments Normal to the Edge of the Slab,” Report SM 77-1, University of Washington, Seattle, WA.
Hemakom, R., 1975, “Strength and Behavior of Post-Tensioned Flat Plates with Unbonded Tendons,” PhD dissertation, The University of Texas at Austin, Austin, TX.
Himawan, A., and Teng, S., 2014, “Cyclic Behavior of Post-Tensioned Slab-Rectangular Column Connections,” ACI Structural Journal, V. 111, No. 1, Jan.-Feb., pp. 177-188. doi: 10.14359/51686516
Himawan, S. A. S., 2012, “Shear Strength of Slab-Column Connections under Gravity and Cyclic Lateral Loading,” PhD dissertation, Nanyang Technological University, Singapore, 275 pp.
Jin, M.-N., 2007, “Deformation Capacity of Post-Tensioned Flat Plate Slab,” MS thesis, Hanyang University, Seoul, South Korea. (in Korean)
Joint ACI-ASCE Committee 352, 2011, “Guide for Design of Slab-Column Connections in Monolithic Concrete Structures (ACI 352.1R-11),” American Concrete Institute, Farmington Hills, MI, 28 pp.
Joint ACI-ASCE Committee 423, 2017, “Recommendations for Concrete Members Prestressed with Single-Strand Unbonded Tendons (ACI 423.3R-17),” American Concrete Institute, Farmington Hills, MI, 24 pp.
Kallage, M. R., 1993, “Punching Shear Strength of Continuous Post-
Tensioned Concrete Flat Plate,” MS thesis, University of Ottawa, Ottawa, ON, Canada.
Kang, T. H.-K., and Wallace, J. W., 2006, “Punching of Reinforced and Post-Tensioned Concrete Slab-Column Connections,” ACI Structural Journal, V. 103, No. 4, July-Aug., pp. 531-540. doi: 10.14359/16429
Kang, T. H.-K.; Lafave, J. M.; Robertson, I. N.; and Hawkins, N. M., 2007, “Post-Tensioned Slab-Column Connections,” Concrete International, V. 29, No. 4, Apr., pp. 70-77.
Kang, T. H.-K.; Robertson, I. N.; Hawkins, N. M.; and Lafave, J. M., 2008, “Recommendations for Design of Post-Tensioned Slab-Column Connections Subjected to Lateral Loading,” PTI JOURNAL, V. 6, No. 1, Feb., pp. 45-59.
Kani, G. N. J., 1967, “How Safe Are Our Large Reinforced Concrete Beams?” ACI Journal Proceedings, V. 64, No. 3, Mar., pp. 128-141. doi: 10.14359/7549
Kim, M.-N., 2007, “Deformation Capacity of Post-Tensioned Flat Plate Slab,” MS thesis, Hanyang University, Seoul, South Korea. (in Korean)
Kordina, K., and Nölting, D., 1984, “Versuche zum Durchstanzen ohne Verbund Vorgespannter Flachdecken,” Technische Universität Braunschweig, Braunschweig, Germany, 103 pp.
Kosut, G. M.; Burns, N. H.; and Winter, C. V., 1985, “Test of Four-Panel Post-Tensioned Flat Plate,” Journal of Structural Engineering, ASCE, V. 111, No. 9, pp. 1916-1929. doi: 10.1061/(ASCE)0733-9445(1985)111:9(1916)
Kuchma, D. A.; Hawkins, N. M.; Kim, S.-H.; Sun, S.; and Kim, K. S., 2008, “Simplified Shear Provisions of the AASHTO LRFD Bridge Design Specifications,” PCI Journal, V. 53, No. 3, pp. 55-73. doi: 10.15554/pcij.05012008.53.73
Long, A. E., and Cleland, D. J., 1993, “Post-Tensioned Concrete Flat Slabs at Edge Columns,” ACI Materials Journal, V. 90, No. 3, May-June, pp. 207-213. doi: 10.14359/4223
Martinez-Cruzado, J. A., 1993, “Experimental Study of Post-Tensioned Flat Plate Exterior Slab-Column Connections Subjected to Gravity and Biaxial Loading,” PhD dissertation, University of California, Berkeley, Berkeley, CA,
Melges, J. L. P., 2001, “Experimental Analysis of Punching in Reinforced and Prestressed Concrete Slabs,” PhD dissertation, University of São Paulo, São Paulo, SP, Brazil.
Moehle, J. P., 1988, “Strength of Slab-Column Edge Connections,” ACI Structural Journal, V. 85, No. 1, Jan.-Feb., pp. 89-98. doi: 10.14359/2995
Ojo, T., and Roberts-Wollmann, C., 2022, “Comparison of Post-
Tensioned Slabs with Banded-Uniform and Banded-Banded Tendon Arrangements,” ACI Structural Journal, V. 119, No. 4, July, pp. 211-223. doi: 10.14359/51734493
Okamura, H., and Higai, T., 1980, “Proposed Design Equation for Shear Strength of Reinforced Concrete Beams without Web Reinforcement,” Proceedings of the Japan Society of Civil Engineers, V. 1980, No. 300, pp. 131-141. doi: 10.2208/jscej1969.1980.300_131
Prawatwong, U.; Warnitchai, P.; and Tandian, C. H., 2012, “Bonded PT Slab-Column Connections with and without Drop Panel Subjected to Earthquake Loading,” 15th World Conference on Earthquake Engineering (15WCEE), Lisbon, Portugal, V. 1, pp. 20533-20542.
Qaisrani, A.-N., 1993, “Interior Post-Tensioned Flat-Plate Connections Subjected to Vertical and Biaxial Lateral Loading,” PhD dissertation, University of California, Berkeley, Berkeley, CA.
Ragab, M. S.; Riad, K. H.; and Zaher, A. H., 2014, “Punching Behavior of Post-Tensioned High Strength Concrete Slabs,” World Applied Sciences Journal, V. 32, No. 4, pp. 527-539. doi: 10.5829/idosi.wasj.2014.32.04.14529
Ramos, A. P.; Lúcio, V. J. G.; and Faria, D. M. V., 2014, “The Effect of the Vertical Component of Prestress Forces on the Punching Strength of Flat Slabs,” Engineering Structures, V. 76, pp. 90-98. doi: 10.1016/j.engstruct.2014.06.039
Rice, P. F., and Hoffman, E. S., 1972, Structural Design Guide to the ACI Building Code, first edition, Van Nostrand Reinhold Company, New York.
Saqan, E. I., and Frosch, R. J., 2009, “Influence of Flexural Reinforcement on Shear Strength of Prestressed Concrete Beams,” ACI Structural Journal, V. 106, No. 1, Jan.-Feb., pp. 60-68. doi: 10.14359/56284
Shatila, M. M., 1987, “Strength of Prestressed Concrete Slab-Edge Column Connections with Stud Shear Reinforcement,” MS thesis, University of Calgary, Calgary, AB, Canada, 223 pp.
Shehata, I. A., 1982, “Punching of Prestressed and Non-Prestressed Reinforced Concrete Flat Slabs,” MS thesis, Polytechnic of Central London, London, UK.
Silva, R. J. C.; Regan, R. E.; and Melo, G. S. S. A., 2007, “Punching of Post-Tensioned Slabs—Tests and Codes,” ACI Structural Journal, V. 104, No. 2, Mar.-Apr., pp. 123-132. doi: 10.14359/18524
Smith, S. W., and Burns, N. H., 1974, “Post-Tensioned Flat Plate to Column Connection Behavior,” PCI Journal, V. 19, No. 3, pp. 74-91. doi: 10.15554/pcij.05011974.74.91
Sunidja, H.; Foutch, D. A.; and Gamble, W. L., 1982, “Response of Prestressed Concrete Plate-Edge Column Connections,” Structural Research Series No. 498, University of Illinois Urbana-Champaign, Urbana, IL.
Trongtham, N., and Hawkins, N. M., 1977, “Moment Transfer to Columns in Unbonded Post-Tensioned Prestressed Concrete Slabs,” Report SM 77-3, University of Washington, Seattle, WA.