Dynamic tensile strength enhancement of concrete in split Hopkinson pressure bar test

Abstract

Split Hopkinson pressure bar technique has been widely used to measure the dynamic tensile strength of concrete materials. Most experimental results show that the tensile strength of concrete material increases with strain rates. However, the dynamic tensile strength derived from the split Hopkinson pressure bar test is affected by lateral inertia confinement, which may lead to the overestimation of dynamic mechanical properties of concrete materials. The true dynamic characteristics of concrete materials are not actually shown by experimental data. It is impossible to completely eliminate the influence of lateral inertia confinement in split Hopkinson pressure bar tests. In this study, a rate-insensitive material model is used in commercial finite element software to study how the lateral inertia confinement affects the dynamic tensile strength of concrete material at strain rates between 30/s and 150/s. Comparison of finite element results and split Hopkinson pressure bar test results shows that the dynamic tensile strength enhancement of concrete materials is strongly influenced by the inertial effect. The dynamic increase factor of concrete materials which remove the influence of lateral inertia confinement in split Hopkinson pressure bar tests can reflect the true dynamic characteristics of concrete materials. It is also found that the influence of lateral inertia confinement is related to the size of the specimen.