Effect of Initial Static Load and Dynamic Load on Concrete Dynamic Compressive Failure

Abstract

Concrete structures often suffer from multiple dynamic loads, or prior to being subjected to dynamic loads have already withstood initial loads. The mechanical properties of concrete materials under dynamic loads may be closely linked to initial loading history that concrete suffers. This paper deals with the investigation of the effect of initial static load and initial dynamic load on dynamic compressive failure of concrete materials based on numerical simulations. A meso-scale modeling method was established and a total of 147 three-dimensional concrete cubic models were simulated. It is demonstrated in research results that the strain rate effect of concrete is relatively weak under low strain rates, while the strain rate effect is significantly enhanced under high strain rates. Dynamic compressive strength under different dynamic loads gradually decreases with the increasing initial static load and the increasing strain rate can weaken the influence of initial static load on dynamic compressive strength of concrete. When dynamic load changes in hardening stage, tangent modulus has a sudden increase and compressive stress reaches a new peak strength. A sudden increase of dynamic load in softening stage reverses the postpeak softening to postpeak hardening followed by a second peak strength. Initial dynamic load plays an important role in dynamic compressive failure of concrete, especially under low strain rates. The numerical results compare well with the existing test results.