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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Torsional Strenth of Prestressed Concrete Members
Author(s): Paul Zia
Publication: Journal Proceedings
Appears on pages(s): 1337-1360
Abstract:Reported are the results of torsional tests of 68 pre- tensioned and plain concrete members consisting of rectangular, T- and l-sections. Some of the specimens also contained web reinforcement in the form of ties. For the rectangular and T-sections, the test results com- pare closely with the predicted stren th by a modification of Cowan’s failure criterion. Actor 8ing to this criterion, which is noted as a close approximation of Mohr’s failure theory, the optimum uniform prestress is 70 percent of the concrete cylinder strength. Corresponding to this optimum value, the torsional strength of a member is increased to 281 percent of that of the similar plain concrete member if the cylinder strength is 6000 psi. For the l-sections, the test results exceed considerably the predicted strength. Explanation of this discrepancy is offered OS being the consequence of stress redistribu- tion after the initial cracking. However, it is suggested that the usable sirength of such a section be token OS the cracking moment, since the crocks due to torsion remain open on unloading and thus permanently damage the concrete member.
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