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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: Deflections of Reinforced Concrete Members: A Simple Approach
Author(s): Pieter C. Pretorius
Publication: Journal Proceedings
Appears on pages(s): 805-812
Keywords: beams (supports); concrete slabs; cracking (fracturing); creep properties; deflection; modulus of elasticity; moments of inertia; reinforced concrete;
stiffness; structural analysis.
Abstract:A new simplified method for long-term deflection calculations of reinforced concrete members is presented. The method defines a modular ratio for creep conditions based on laboratory verified strain distributions in beams for both immediate and long-term conditions. A simple formula is derived for the ratio of long-term to immediate deflections. A value for the creep factor is assumed but a series of curves is recommended that relates the creep factor to ambient relative humidity, age of loading, and surface area to the volume ratio of the member. Calculated deflections using the method are compared with laboratory measured values reported in the literature.
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