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.