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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: Small Bar Spacing or Cover-A Bond
Problem for the Designer
Author(s): Phil M. Ferguson
Publication: Journal Proceedings
Appears on pages(s): 435-439
Keywords: bond (concrete to reinforcement); bonding; bond stress; cover; reinforced concrete; reinforcing steels;solicing; splitting tensile strength; stirrups.
Abstract:Two recent research reports about bond and development length indicate that both bar cover and bar spacing are very critical factors. For example, #9 bars, within heavy stirrups and having 2.1 in. clear cover over the bars, developed only 55 percent as much bond resistance when spaced on 2.5 in. centers as when spaced on 4.2 in. centers; and the latter spacing developed only 90 percent of that assumed in the 1977 ACI Building Code requirements for development length. Pending further Code revisions, the author suggests what the designer can do to avoid this weakness.
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