Title:
Computing Deflections Using ACI CODE-318-19 and Beyond, Part 3
Author(s):
Peter H. Bischoff
Publication:
Concrete International
Volume:
47
Issue:
4
Appears on pages(s):
47-50
Keywords:
slab, beam, load, limit
DOI:
10.14359/51746696
Date:
4/1/2025
Abstract:
This is the third article in a five-part series. While Parts 1 and 2 review the procedure and basis for computing deflection of reinforced concrete with a new expression for the effective moment of inertia Ie first adopted in ACI CODE-318-19, this article examines the implications of this change for satisfying deflection limits of beams and one- and two-way slabs. A need is seen to revise current minimum thickness values for beams.
Related References:
1. Bischoff, P.H., “Computing Deflections Using ACI CODE-318-19 and Beyond, Part 1,” Concrete International, V. 47, No. 2, Feb. 2025, pp. 47-50.
2. Bischoff, P.H., “Computing Deflections Using ACI CODE-318-19 and Beyond, Part 2,” Concrete International, V. 47, No. 3, Mar. 2025, pp. 51-54.
3. ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary (ACI 318R-19),” American Concrete Institute, Farmington Hills, MI, 2019, 624 pp.
4. ACI Committee 318, “Building Code Requirements for Reinforced Concrete (ACI 318-63),” American Concrete Institute, Farmington Hills, MI, 1963, 144 pp.
5. Ferguson, P.M., Reinforced Concrete Fundamentals, third edition, John Wiley and Sons, New York, 1973, 750 pp.
6. ACI Committee 318, “Building Code Requirements for Reinforced Concrete (ACI 318-71),” American Concrete Institute, Farmington Hills, MI, 1971, 78 pp.
7. ACI Committee 318, “Building Code Requirements for Reinforced Concrete (ACI 318-83),” American Concrete Institute, Farmington Hills, MI, 1983, 111 pp.
8. 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.
9. Bischoff, P.H., “Comparison of Existing Approaches for Computing Deflection of Reinforced Concrete,” ACI Structural Journal, V. 117, No. 1, Jan. 2020, pp. 231-240.
10. Bischoff, P.H., and Veysey, S., “Minimum Thickness Requirements Needed to Satisfy Deflection Limits for One-Way Reinforced Concrete Construction,” Canadian Society for Civil Engineering (CSCE) 2011 General Conference, Ottawa, ON, Canada, June 14-17, 2011.
11. Veysey, S., and Bischoff, P.H., “Minimum Thickness Values for Deflection Control of FRP Reinforced Concrete,” Proceedings of the 11th International Symposium on Fibre Reinforced Polymer for Reinforced Concrete Structures (FRPRCS-11), J. Barros and J. Sena-Cruz, eds., Guimarães, Portugal, June 26-28, 2013, 10 pp.
12. Bischoff, P.H., and Scanlon, A., “Span-Depth Ratios for One-Way Members Based on ACI 318 Deflection Limits,” ACI Structural Journal, V. 106, No. 5, Sept.-Oct. 2009, pp. 617-626.
13. Scanlon, A., and Suprenant, B.A., “Estimating Two-Way Slab Deflections,” Concrete International, V. 33, No. 7, July 2011, pp. 29-34.
14. ACI Committee 435, “Report on Deflection of Nonprestressed Concrete Structures (PRC-435-20),” American Concrete Institute, Farmington Hills, MI, 2020, 56 pp.
15. Branson, D.E., Deformation of Concrete Structures, McGraw-Hill, New York, NY, 1977, 546 pp.
16. Bertero, R., and Bertero, A., “Statistical Evaluation of Minimum Thickness Provisions for Slab Deflection Control,” ACI Structural Journal, V. 115, No. 6, Nov. 2018, pp. 1659-1670.
17. Bertero, R., and Bertero, A., Closure to Discussion of “Statistical Evaluation of Minimum Thickness Provisions for Slab Deflection Control,” ACI Structural Journal, V. 116, No. 5, Sept. 2019, pp. 301-302.