• 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.

International Concrete Abstracts Portal


Title: Comparison of Existing Approaches for Computing Deflection of Reinforced Concrete

Author(s): Peter H. Bischoff

Publication: Structural Journal

Volume: 117

Issue: 1

Appears on pages(s): 231-240

Keywords: beams; deflection; effective moment of inertia; minimum thickness; slabs

Date: 1/1/2020

This paper evaluates the approach adopted by ACI 318-19 for computing deflection of reinforced concrete. Comparison is made with the European approach and Branson’s approach used in previous editions of ACI 318. The adopted approach uses a rational expression for the effective moment of inertia, Ie, with a reduced cracking moment that gives greater values of computed deflection for lightly reinforced slabs. The impact of this change on member stiffness and minimum thickness requirements related to immediate and long-term deflection limits for serviceability is evaluated for beams and one-way slabs. Appropriate limits for maximum service load and member span are provided for slabs, and more stringent requirements are needed for minimum thickness of beams. Information about two-way slabs is also provided.


Please enter this 5 digit unlock code on the web page.