A novel method of predicting shear strength of fiber-reinforced high-strength concrete based on cube specimens: part-1

Shear failure in concrete structures is sudden and catastrophic. From past few decades, the shear behavior of concrete of various kinds is studied but even today there is no one universally accepted single shear test setup acceptable to all wide range of concrete. In this study, a novel method of predicting shear strength is proposed. From the literature and different standard codes, it is found that, shear strength of plain concrete becomes constant beyond certain compressive strength which is mentioned differently in various codes and researchers. The aim was to improve the shear strength of HSC by using crimped steel fibers (CSF). In this part of investigation, two aspect ratios, i.e., 60 and 100, with four fiber dosages of 0, 0.25, 0.50, and 0.75% by volume of concrete were considered for improving shear strength of concrete compressive strength ranging from 50 to 80 MPa. To understand the significance of size of aggregates, two different nominal sizes viz., 12.5 and 20 mm, were considered. A total number of 378 specimens, which includes cubes and cylinders were cast and tested to determine the compressive strength, shear strength, and split tensile strength of HSC. From experimental results, it was found that, the ideal dosage of steel fibers for HSC was 0.50 and 0.75% for improvement of compressive strength, shear strength, and for split tensile strength, respectively. Further, it was found that 12.5-mm aggregate provides greater compressive, split tensile, and shear strengths compared to 20-mm aggregate. Fibers with aspect ratio 100 were shown to improve the compressive, split tensile, and shear strengths. The experimental shear strength results are compared with various models proposed on different shear test setups and found Khanlou et al., and Khaloo and Kim models are in good co-relation with experimental shear strength. Except for Sharma model, various models proposed on deep beams are not in good correlation with experimental results.