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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: Size Effect in Shear Failure of Longitudinally Reinforced Beams
Author(s): Zdenek P. Bazant and Jin-Keun Kim
Publication: Journal Proceedings
Appears on pages(s): 456-468
Keywords: beams (supports); building codes; cracking (fracturing); dimensional analysis; failure; reinforced concrete; shear properties; statistical analysis;structural analysis.
Abstract:Consequences of recent fracture mechanics studies of concrete for analyzing diagonal shear failure of longitudinally reinforced beams or one-way slabs without shear reinforcement were studied. The cracking produced by shear was assumed to propagate with a dispersed zone of microcracks at the fracture front. Dimensional analysis of the energy release rate then shows that the nominal shear stress at failure should not be a constant but should vary as (I + d/d, A,) in which d = beam depths, d, = maximum aggregate size, and A, = constant. For relatively small beams, representing the great majority of those tested in the laboratories, the nominal stress at failure is nearly constant; however, for much deeper beams it considerably declines with increasing size. This trend is confirmed by previous experimental results. In addition to the size effect, a rational formula for the effect of steel ratio and shear span is derived. Comparisons with existing test data involving nearly 300 tests indicate that, compared to the formulas in the current building codes, the coefficient of variation of deviations from the formula is reduced to less than one-half.
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