Pure rate effect on compressive strength of concrete

Abstract

Dynamic Increase Factor (DIF) has been used to consider the compressive strength enhancement of concrete at the high and intermediate strain rates. However, DIF formulae suggested until now include the inertia effects as well as the rate effect because the DIF formulae has been assumed as a function of only the strain rate and the inertia effects cannot be avoided in tests at the high and intermediate strain rate region. Therefore, applying the DIF to design or analysis of social infrastructures may be dangerous because the resistance by the inertia effects are considered repetitively. In this study, an apparent DIF formula, which includes the inertia effects, was proposed by introducing terms related with the strain acceleration, which represent the axial and radial inertia effects. Then, a nonlinear regression analysis was conducted to determine the coefficients in the apparent DIF formula with results of Split Hopkinson Pressure Bar (SHPB) tests for concrete. Finally, the DIF formula excluding the axial and radial inertia effects was proposed for compressive strength of concrete at the high and intermediate strain rates.