SHEAR STRENGTH PREDICTION FOR DEEP BEAMS

Abstract

This paper proposes a softened strut-and-tie model for determining the shear strengths of deep beams. The proposed model originates from the strut-and-tie concept and satisfies equilibrium, compatibility, and constitutive laws of cracked reinforced concrete. The shear strength predictions of the proposed model and the empirical formulas of the American Concrete Institute (ACI) 318-95 Code are compared with the collected experimental data of 123 deep beams. The comparison shows that the performance of the softened strut-and-tie model is better than the ACI Code approach for all the parameters under comparison. The parameters reviewed include the ratios of horizontal and vertical reinforcement, concrete strength, and the shear span-depth ratio. The softened strut-and-tie model can be further developed to improve the current deep beam design procedures by incorporating the actual shear resisting mechanisms in predicting shear strength supply of deep beams.