Title:
Punching Shear Strength of Flat Slab-Edge Column Connections with Outward Eccentricity of Loading
Author(s):
Nivea G. B. Albuquerque, Guilherme S. Melo, and Robert L. Vollum
Publication:
Structural Journal
Volume:
113
Issue:
5
Appears on pages(s):
1117-1129
Keywords:
edge columns; flat slab; punching shear; outward eccentricity; slab-column connections
DOI:
10.14359/51689156
Date:
9/1/2016
Abstract:
Thirteen tests were carried out to investigate the effect of outwards eccentricity on the punching resistance of flat slab edge column connections. The slabs measured 2350 x 1700 mm (92.5 x 66.9 in.) on plan and were 180 mm (7.1 in.) thick. One end of the slab was supported on a 300 mm (11.8 in.) square column with a boot at its base for imposition of eccentricity. The other end was supported on a fixed roller support that extended across the full slab width of 1700 mm (66.9 in.). Four point loads were applied to the unsupported slab edges. The tested variables were eccentricity and the areas of flexural, shear, and torsion reinforcement. Presented test results include reinforcement strains, displacements, rotations, crack patterns, failure modes, and ultimate loads. The ACI 318 design procedure for punching shear at edge columns with outwards eccentricity is shown to be overly conservative unless the interaction between punching shear and unbalanced moment is reduced as permitted by the code. The EC2 design procedure is unsatisfactory and a modification is proposed.
Related References:
1. Andersson, J. L., “Punching of Slabs Supported on Columns at Free Edges,” Nordisk Betong, Stockholm, Sweden, 1966, pp. 179-200. (in Swedish)
2. Kinnunen, S., “Tests on Concrete Slabs Supported on Columns at Free Edges,” National Swedish Building Research Summaries R2:1971, Stockholm, Sweden, 1971.
3. Zaghlool, E. R. F., “Strength and Behavior of Corner and Edge Column-Slab Connections in Reinforced Concrete Flat Plates,” PhD thesis, Department of Civil Engineering, University of Calgary, Calgary, AB, Canada, 1971, 366 pp.
4. Hawkins, N. M., and Corley, W. G., “Moment Transfer to Columns in Slabs with Shearhead Reinforcement,” Shear in Reinforced Concrete, SP-42, American Concrete Institute, Farmington Hills, MI, 1974, pp. 847-879.
5. Mortin, J. D., and Ghali, A., “Connection of Flat Plates to Edge Columns,” ACI Structural Journal, V. 88, No. 2, Mar.-Apr. 1991, pp. 191-198.
6. El-Salakawy, E. F.; Polak, M. A.; and Soliman, M. H., “Reinforced Concrete Slab-Column Edge Connections with Shear Studs,” Canadian Journal of Civil Engineering, V. 27, No. 2, 2000, pp. 338-348. doi: 10.1139/l99-062
7. Sherif, A.; Emara, M. B.; Hassanein, A.; and Magd, S. A., “Effect of the Column Dimensions on the Punching Shear Strength of Edge Column-Slab Connections,” Punching Shear in RC Slabs, SP-232, M. A. Polak, ed., American Concrete Institute, Farmington Hills, MI, 2005, pp. 175-192.
8. Narashiman, N., “Shear Reinforcement in Reinforced Concrete Column Heads,” PhD thesis, Imperial College, University of London, London, UK, 1971.
9. Stamenković; A., and Chapman, J. C., “Local Strength at Column Heads at Flat Slabs Subjected to a Combined Vertical and Horizontal Loading,” Proceedings Institution of Civil Engineering, Part 2, London, UK, 1974.
10. Regan, P. E., “Behaviour of Reinforced Concrete Flat Slabs,” CIRIA Report 89, London, UK, 1981, 90 pp.
11. Moehle, J., “Strength of Slab-Column Edge Connections,” ACI Structural Journal, V. 85, No. 1, Jan.-Feb. 1988, pp. 89-98.
12. Eurocode 2, “Design of Concrete Structures—Part 1-1: General Rules and Rules for Buildings,” CEN, EN 1992-1-1, Brussels, Belgium, 2004, 225 pp.
13. ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14),” American Concrete Institute, Farmington Hills, MI, 2014, 519 pp.
14. Albuquerque, N. G. B., “Behavior of Connections between Reinforced Concrete Flat Slabs and Edge Columns with Inward and Outward Eccentricities,” PhD thesis, Civil Engineering Department, University of Brasília, Brasilia, Brazil, 2014, 204 pp. (in Portuguese)
15. Ghali, A.; Gayed, R. B.; and Dilger, W., “Design of Concrete Slabs for Punching Shear: Controversial Concepts,” ACI Structural Journal, V. 112, No. 4, July-Aug. 2015, pp. 505-514. doi: 10.14359/51687707
16. MacGregor, J. G., and Wight, J. K., Reinforced Concrete—Mechanics and Design, fourth edition, Prentice Hall, Upper Saddle River, New Jersey, 2005, 1111 pp.
17. Joint ACI-ASCE Committee 352, “Guide for Design of Slab-Column Connections in Monolithic Concrete Structures (ACI 352.1R-11),” American Concrete Institute, Farmington Hills, MI, 2011, 28 pp.
18. Muttoni, A., “Punching Shear Strength of Reinforced Concrete Slabs without Transverse Reinforcement,” ACI Structural Journal, V. 105, No. 4, July-Aug. 2008, pp. 440-450.