Strain-Based Shear Strength Model for Slender Beams without Web Reinforcement

Abstract

A theoretical model was developed to predict the shear strength of slender reinforced concrete beams without shear reinforcement. The shear force applied to a cross section of the beam was assumed to be resisted primarily by the compression zone of intact concrete rather than by the tension zone. The shear capacity of the cross section was defined based on the material failure criteria of concrete: failure controlled by compression and failure controlled by tension. In the evaluation of the shear capacity, interaction with the normal stresses developed by the flexural moment in the cross section was considered. Because the magnitude and distribution of the normal stresses vary due to the flexural deformation of the beam, the shear capacity of the beam was defined as a function of the flexural deformation. The shear strength of the beam and the location of the critical section were determined at the intersection between the shear capacity and the shear demand curves. The proposed strength model was verified by comparisons to prior test results.