Experimental study on dynamic mechanical properties of concrete under direct shear loading

Abstract

Dynamic shear properties of concrete could influence the blast resistance and penetration properties of concrete structures. Compared with the dynamic compressive and tensile characteristics, the dynamic shear properties of concrete are far from being well studied. In this study, dynamic push-off tests under six loading velocities were carried out on concrete specimens with two strength grades to qualify their dynamic shear properties. The process of concrete failure was recorded by a high-speed camera, and the deformation of the specimen was obtained by the digital image correlation (DIC) technique. The test results show that the shear properties of concrete have remarkable loading rate sensitivity, and the dynamic shear strength can be increased even 10 times at high loading rates. The rate sensitivity of concrete under shear is higher than that under compression, but lower than tension if the stress rate is below about 2 × 105 MPa/s. The mechanical background of the rate effect on concrete shear strength is revealed through testing results and theoretical analysis according to the different failure modes of the specimen under different loading rates. Based on experimental results, empirical equations of the dynamic increase factors (DIFs) for the shear strength, the shear slip, and the shear slip stiffness are proposed to predict the dynamic shear properties of concrete.