Title:
Alternative Design Procedures for Torsion in ACI 318-19: A Comparative Study
Author(s):
Allan Kuan, Edvard P.G. Bruun, Evan C. Bentz, and Michael P. Collins
Publication:
Symposium Paper
Volume:
344
Issue:
Appears on pages(s):
64-91
Keywords:
reinforced concrete; prestressed concrete; torsion; design codes; shear; moment
DOI:
10.14359/51728291
Date:
10/1/2020
Abstract:
Although the torsion design procedures in ACI 318-19 are simple and broadly applicable, the resulting designs tend to be conservative. To address this, clause 9.5.4.6 in ACI 318-19 permits the use of an alternative design procedure when designing members with an aspect ratio ≥ 3 for torsion, provided that the alternative procedure has been shown to agree with the results of comprehensive tests. This paper evaluates and compares the torsion design
procedures in CSA A23.3:19 and the PCI Design Handbook 8th edition with those in ACI 318-19. Each of the three
methods are found to show good agreement with 282 tests found in the literature. A comparison of the three concludes that the designs obtained using the ACI method generally require the most reinforcement. More economical designs for members subjected to relatively low and high torques can be obtained by using the PCI and CSA methods respectively. A design example of a spandrel beam using the three methods is presented, and then further conclusions
are stated to guide practicing engineers on the relative strengths and weaknesses of each procedure.
Related References:
1. ACI Committee 318 “Building Code Requirements for Reinforced Concrete (ACI 318-71),” American Concrete Institute, Detroid, MI, 1971, 144 pp.
2. MacGregor, J.G. and Ghoneim, M.G., “Design for Torsion”, ACI Structural Journal, Vol. 92, No. 2, March-April 1995, pp. 211-218.
3. PCI Design Handbook – Precast and Prestressed Concrete, Eighth Edition, Precast/prestressed Concrete Institute, Chicago, IL, 2017.
4. ACI Committee 318 “Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary (ACI 318R-19),” American Concrete Institute, Farmington Hills, MI, 2019, 623 pp.
5. Rahal, K.N., “Combined Torsion and Bending in Reinforced and Prestressed Concrete Beams Using Simplified Method for Combined Stress-Resultants,” ACI Structural Journal, Vol. 104, No. 38, July-August, 2007, pp. 402-411.
6. Rahal, K.N., “Torsional strength of normal and high strength reinforced concrete beams,” Engineering Structures, Vol. 56, 2013, pp. 2206-2216.
7. Collins, M.P. and Mitchell, D., "Shear and Torsion Design of Prestressed and Non-Prestressed Concrete Beams", Journal of the Prestressed Concrete Institute, Vol. 25, No. 5, September-October. 1980, pp. 32-100.
8. CSA A23.3:19, “Design of Concrete Structures,” Canadian Standards Association, Mississauga, ON, Canada, 2019, 295 pp.
9. American Association of State Highway and Transportation Officials, “AASHTO LRFD Bridge Design Specifications and Commentary,” 8th Edition, Washington, D.C., 2017, 1781 pp.
10. EN 1992-1-1:2004, “Eurocode 2: Design of Concrete Structures- Part 1-1: General Rules and Rules for Buildings,” European Committee for Standardization, Brussels, Belgium, 2004, 225 pp.
11. BD-002 “AS 3600:2018 Concrete Structures,” Standards Australia, Sydney, Australia, 2018, 259 pp.
12. Zia, P. and Hsu, T.C., “Design for Torsion and Shear in Prestressed Concrete Flexural Members”, PCI Journal, Vol. 49, No. 3, May-June, 2004, pp. 34-42.
13. Zia, P., and McGee, W.D., “Torsion Design of Prestressed Concrete”, PCI Journal, Vol. 19, No. 2, Mar-Apr, 1974, pp. 46-65.
14. Bernardo, L.F.A. and Lopes, S.M.R., “Torsion in High-Strength Concrete Hollow Beams: Strength and Ductility Analysis”, ACI Structural Journal, Vol. 106, No. 1, January-February, 2009, pp. 39-48.
15. Fang, I.K. and Shiau, J.K., “Torsional Behaviour of Normal- and High-Strength Concrete Beams”, ACI Structural Journal, Vol. 101, No. 3, May-June 2004, pp. 304-313.
16. Hsu, Thomas T. C., "Torsion of Structural Concrete - Behavior of Reinforced Concrete Rectangular Members," Torsion of Structural Concrete, SP-18, American Concrete Institute, Detroit, 1968, pp. 261-306.
17. Jeng, C.H., Peng, S.F., Chiu, H.J. and Hsiao, C.K, “New Torsion Experiment on large-Sized Hollow Reinforced Concrete Beams,” ACI Structural Journal, Vol. 111, No. 6, November-December 2014, pp. 1469-1480.
18. Koutchoukali, N.E. and Belarbi, A., “Torsion of High-Strength Reinforced Concrete Beams and Minimum Reinforcement Requirement”, ACI Structural Journal, Vol. 98, No. 4, July-August 2001, pp. 462-469.
19. Lampert, P., and Thurlimann, B., “Torsionsversuche an Stahlbetonbalken,” Bericht Nr. 6506-2, Institut fur Baustatik, ETH Zurich, Germany, Jan. 1968.
20. McMullen, A.E. and Rangan, B.V., “Pure Torsion in Rectangular Sections – A Re-Examination,” ACI Journal, Vol. 75, No.10, October 1978, pp. 511-519.
21. McMullen, A. E., and Warwaruk, J., “The Torsional Strength of Rectangular Reinforced Beams Subjected to Combined Loading,” Report No. 2, Civil Engineering Department, University of Alberta, Alberta, Canada, 1967, 162 pp.
22. Mitchell, D. and Collins, M.P., "Influence of Prestressing on Torsional Response of Concrete Beams," Journal of the Prestressed Concrete Institute, Vol. 23, No. 3, May-June 1978, pp. 54-73.
23. Mardukhi, J., “The Behaviour of Uniformly Prestressed Concrete Box Beams in Combined Torsion and Bending”, M.A.Sc. Thesis, 1974, 72 pp.
24. Pandit, G.S. and Warwaruk, J., “Reinforced Concrete Beams in Combined Bending and Torsion,” American Concrete Institute Special Publication, SP-18, 1968, pp. 133-164.
25. Rasmussen, L.J. and Baker, G., “Torsion in Reinforced Normal and High-Strength Concrete Beams – Part 1: Experimental Test Series”, ACI Structural Journal, Vol. 92, No. 1, January-February 1995, pp. 56-62.
26. Wafa, F.F., Shihata, S.A., Ashour S.A. and Akhtaruzzaman, A.A., “Prestressed High-Strength Concrete Beams under Torsion,” Journal of Structural Engineering, Vol. 121, No. 9, September 1995, pp. 1280-1286.
27. Collins, M.P., Walsh, P.F., Archer, F.E., and Hall, A.S., "The Ultimate Strength of Reinforced Concrete Beams Subjected to Combined Torsion and Flexure," American Concrete Institute Special Publication, SP-18, 1968, pp. 379-402.
28. Goode, C.D. and Helmy, M.A., “Ultimate Strength of Reinforced Concrete Beams in Combined Bending and Torsion,” American Concrete Institute Special Publication, SP-18, 1968, pp. 357-378.
29. Kemp, E.L., “Behavior of Concrete Members Subject to Torsion and to Combined Torsion, Bending, and Shear,” American Concrete Institute Special Publication, SP-18, 1968, pp. 179-202.
30. Iyengar, K.T.S.R. and Rangan, B.V., “Strength and Stiffness of Reinforced Concrete Beams Under Combined Bending and Torsion,” American Concrete Institute Special Publication, SP-18, 1968, pp. 403-440.
31. Onsongo, W. M., “The Diagonal Compression Field Theory for Reinforced Concrete Beams Subjected to Combined Torsion, Flexure, and Axial Load,” PhD thesis, Department of Civil Engineering, University of Toronto, Toronto, Ontario, Canada, 1978, 246 pp.
32. Lampert, P., and Thurlimann, B., “Torsions-Biege-Versuche an Stahlbetonbalken,” Bericht Nr. 6506-3, Institut fur Baustatik, ETH Zurich, Germany, Jan. 1969.
33. Collins, M.P. and Lampert, P., "Torsion, Bending and Confusion - An Attempt to Establish the Facts," Journal of the American Concrete Institute, Vol. 69, No. 8, August 1972, pp. 500-504.
34. Rahal, K.N. and Collins, M.P., “Experimental Evaluation of ACI and AASHTO-LRFD Design Provisions for Combined Shear and Torsion,” ACI Structural Journal, Vol. 100, No.3, May-June 2003, pp 277-282.
35. Klein, G. J., “Design of Spandrel Beams,” PCI Specially Funded Research Project No. 5, Precast/ Prestressed Concrete Institute, Chicago, IL, 1986.
36. Rahal, K.N. and Collins, M.P., "Effect of Thickness of Concrete Cover on the Shear-Torsion Interaction - An Experimental Investigation," ACI Structural Journal, Vol. 92, No. 3, May-June 1995, pp. 334-342.
37. Proestos, G.T., Bentz, E.C. and Collins, M.P., “Maximum Shear Capacity of Reinforced Concrete Members”, ACI Structural Journal, Vol. 115, No. 5, September 2018, pp. 1463-1474.
38. Kuan, A., Bruun, E.P.G., Bentz, E.C., Collins, M.P., “Nonlinear sectional analysis of reinforced concrete beams and shells subjected to pure torsion,” Computers and Structures Vol. 222, October 2019, pp. 118-132.