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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: Dynamic Stiffness of Concrete Beams
Author(s): Kenneth C. Johns and Michel D. Belanger
Publication: Journal Proceedings
Appears on pages(s): 201-205
Keywords: beams (supports); deflection; dynamic structural analysis; moments
of inertia; reinforced concrete; serviceability; static loads; stiffness; structural
Abstract:The stiffness and effective moment of inertia of reinforced concrete beams used in dynamic calculations is investigated experimentally by a study of natural frequency of vibration. Beams are statically loaded to various levels into the cracked regime, then caused to vibrate freely with small amplitudes. Natural frequency is observed and the effective dynamic stiffness is calculated. The evolution of this dynamic stiffness with increased static load or bending moment is studied. Neither gross, cracked, nor effective moments of inertia appear adequate to predict the behavior observed. From the limited number of observations available, a formula is tentatively proposed for a dynamic stiffness.
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