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Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
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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: Spiral Post-Tensioning System for Concrete Members
Author(s): Navapol Krishnamra, Ekasit Limsuwan, and John Dawe
Publication: Structural Journal
Appears on pages(s): 563-571
Keywords: active confinement; combined stress; pipes; post-tensioning; spiral strands; thick-walled
Abstract:Four thick-walled 1008 mm (39.7 in.) long cylindrical specimens with an inside diameter of 304.8 mm (12 in.), a wall thickness of 76.2 mm (3 in.), and a monolithically cast 250 mm (9.8 in.) long flange at either end were fabricated. For three of the specimens, a spiral post-tensioning system consisting of four clockwise and four counterclockwise outside wrapping strands was used. The fourth specimen had eight post-tensioned straight strands. Specimens were fabricated using high-performance, self-consolidating concrete and 12.5 mm (0.5 in.) post-tensioning tendons. Each specimen was supported at the ends and point loaded at the midspan. Spiral specimens were post-tensioned to 25, 50, and 75% of strand capacity, whereas the specimen with straight strands was post-tensioned to 50% strand capacity. The spiral post-tensioning system increased ultimate capacity by 45% when compared with the specimen having longitudinally aligned strands.
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