Experimental and numerical analysis of dynamic splitting behavior of C75 concrete

Based on the assumptions of uniformity and one-dimensional stress wave theory, the splitting tests of C75 concrete were conducted using a large-diameter Hopkinson pressure bar to study its dynamic tensile strength property and strain-rate effect, and the dynamic stress equilibrium was carefully checked. At the same time, the stress contours were visualized with MATLAB, and the theoretical basis for the center cracking of Brazil disc was provided based on the modified Griffith theory. The failure processes of specimens in the dynamic splitting were simulated using LS-DYNA software. The results show that the dynamic tensile strength and the logarithmic strain rate were almost linearly dependent when the strain rate ranged from 100 to 101/s. The specimen broke diametrically at low projectile velocity. Triangular crushed zones appeared at the two ends of the specimen with the increase of projectile velocity, and they became more serious in incident end. Under the 2D condition, the contours of the ratio of the maximum to minimum principal stress of the Brazil disc specimen (σ1/σ3) resembled a closed diamond, and the ratio of compressive strength to tensile strength at the center of the disc specimen had a maximum value of -3.0. The dynamic behaviors of the C75 concrete can be well described using the viscoplastic Cowper-Symonds constitutive mode considering strain rate effect. The simulation of the fracture process showed good agreement with the results observed by using the high-speed photography. The tensile strength of the C75 concrete is much better than that of the C35 concrete with the same water-cement ratio, but its strain rate sensitivity is lower than that of the C30 geopolymer concrete. © 2019, Editorial Board of Journal of Harbin Institute of Technology. All right reserved.