Strain rate and size effects on dynamic compressive behaviour of standard and high-strength concrete

The understanding of dynamic behavior of concrete and its dependence on strain rate and specimen geometry is important to develop insight into the analysis and design of concrete structures subjected to extreme loading. In the present study, the dynamic compressive behaviour of standard concrete (M35) and high-strength concrete (M60) has been studied experimentally at varying strain rates in the range, 78-336 s-1. The specimen geometry has been varied by changing the diameter of the cylindrical concrete specimens as 29.5 and 45 mm. The behavior under compression thus studied under varying strain rate and specimen geometry has been presented in terms of DCS (dynamic compressive strength), DIF (dynamic increase factor), stress-strain relationship, strain, energy absorption density and material failure process. The dynamic material properties have been found to increase with an increase in the strain rate. The DIF with respect to compressive strength for standard and high-strength concrete varied in the range of 1.76-2.65 and 1.28-1.69, respectively. An increment of 165% and 69.6% was obtained in the dynamic compressive strength (DCS) for SC and HSC. The concrete specimen with a larger diameter described a significant increase in DCS, DIF, critical strain, and pre-peak energy density due to end-friction and lateral inertia confinement while no significant effect of specimen diameter was observed on the ultimate strain and total energy density.