EVALUATION OF SHEAR STRENGTH OF HIGH-STRENGTH CONCRETE BEAMS WITHOUT STIRRUPS

In this paper, a comparative analysis on shear behavior of high-strength concrete beams using various international design approaches like ACI [1], Canadian [2], AASHTO [3], European Code [4] and the method proposed by Zararis [5] is presented. Twenty-seven reinforced concrete beams without web reinforcement were tested under three point loading. In addition, 95 other similar beams having similar cross sectional dimensions, concrete strength, and loading conditions are analyzed [6–8]. The shear span-to-depth ratio ranged from 1 to 6 and longitudinal reinforcement ratio from 0.35% to 1.94%. Based on the analysis of total of 122 similar beams, it is observed that shear strength and failure mode depends upon shear span and longitudinal reinforcement ratio. For values of a/d ratio less than 2.5, the experimental shear strength was found greater than that predicted as per different shear design approaches; however for slender beams having a/d ranging from 2.5 to 6, the predicted shear capacity was found greater. It was noted that ACI 318-02[1] predicts shear strength more accurately for values of tensile steel ratio greater than 1 %, whereas design approach proposed by Zararis [5] is more appropriate to be used where tensile steel ratio is less than 1%.