Title: Simplified Modified Compression Field Theory for Calculating Shear Strength of Reinforced Concrete Elements

Author(s): Evan C. Bentz, Frank J. Vecchio, and Michael P. Collins

Publication: Structural Journal

Volume: 103

Issue: 4

Appears on pages(s): 614-624

Keywords: reinforced concrete; safety; shear; strength

DOI: 10.14359/16438

Date: 7/1/2006

Abstract:
This paper summarizes the results of over 100 pure shear tests on reinforced concrete panels. The ACI approach for predicting shear strength as the sum of a diagonal cracking load and a 45-degree truss model predicts the strength of these panels poorly, with an average experimental-over-predicted shear strength ratio of 1.40 with a coefficient of variation of 46.7%. Based on a subset of these experiments, an expressive but relatively complex analysis method called the modified compression field theory (MCFT) was developed in the 1980s that is able to predict full load deformation relationships. This theory can predict the shear strength of these panels with an average shear strength ratio of 1.01 and a coefficient of variation (COV) of only 12.2%. This paper presents a new simplified analysis method that can predict the strength of these panels in a method suitable for “back of the envelope” calculations. This new method gives an average shear strength ratio of 1.11 with a COV of 13.0%. The application of this new simplified method to panels is demonstrated with numerical examples.