A new shear test setup for determining shear strength of normal and high strength concrete

Since the start of the 20th century various investigators proposed different shapes, sizes of specimens to determine the shear strength of concrete and proposed several models. Several disagreements and discussions were surrounding the concept of shear strength, particularly in case of High strength concrete (HSC). In order to compare the shear strengths of Normal Strength Concrete (NSC) with High Strength Concrete, a "New shear test setup" was proposed in this study. From literature and different standard codes, it was found that, the shear strength of plain concrete becomes constant after certain compressive strength. Different authors and codes proposed different strength of concrete beyond which the shear strength becomes constant. The aim of the study was to find the compressive strength beyond which the shear strength becomes constant using the proposed shear test setup. In order to obtain the shear strength, 42 cubes of 150 mm x 150 mm x 150 mm of concrete of varying strength of 20 MPa to 80 MPa were cast and tested. The experimental results were compared with a numerical model based on FEM software ATENA and the existing models proposed in the literature. It was found from the experimental work that the shear strength became constant after a compressive strength of 50 MPa- 60 MPa. According to the shear strength results, there was a significant correlation between experimental results and results predicted using ATENA software. Moreover, the experimental results were compared with the shear strength values predicted by various national building codes and various shear models proposed using the different shear test setups. It was found that the experimental results closely match with the values obtained by AS: 3600-2018 equation and Mattock equation's based on the push-off specimen.