Title:
Response of Prestressed Concrete Beams Subjected to Shear and Torsion
Author(s):
Allan Kuan, Giorgio T. Proestos, Evan C. Bentz, and Michael P. Collins
Publication:
Structural Journal
Volume:
118
Issue:
5
Appears on pages(s):
251-261
Keywords:
design provisions; detailing; interior beams; prestressed concrete; shear; spalling; torsion
DOI:
10.14359/51732833
Date:
9/1/2021
Abstract:
Eccentric loading or compatibility conditions can cause beams in buildings to be subjected to significant torsions. Although design procedures for torsion are based on tests of stand-alone members and require closed stirrups to be used as transverse reinforcement,
interior girders in beam-and-girder construction are usually integral with floor slabs and reinforced with open stirrups. This paper describes an experimental investigation of two post-tensioned companion specimens, designed to represent interior beams with an integral slab, which were loaded to failure under combined moment, shear, and torsion. The specimens were identical, except one was detailed using open stirrups and the other using closed stirrups. The strength of these members was significantly underpredicted by the ACI 318-19 and CSA A23.3-19 codes, which were, on average, conservative by factors of 3.50 and 2.05, respectively. The specimen detailed with open stirrups did not demonstrate a significantly different torsional response than the specimen containing closed stirrups.
Related References:
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2. 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.
3. CSA A23.3:19, “Design of Concrete Structures,” Canadian Standards Association, Mississauga, ON, Canada, 2019, 295 pp.
4. Collins, M. P., and Lampert, P., “Redistribution of Moments at Cracking-the Key to Simpler Torsion Design,” Analysis of Structural Systems for Torsion, SP-35, American Concrete Institute, Farmington Hills, MI, Jan. 1973, pp. 343-383.
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