| Summary: | Affected by static loads, ahead of the dynamic loads such as blasting, flowage, and earthquakes, concrete structures are already in various degrees of damage. Against this engineering backdrop, the damage degree should be considered in seismic design and disaster mitigation for concrete structures. To investigate the dynamic mechanical properties, energy evolution, and fracture mechanism of damaged concrete under dynamic load. The damage models of the dynamic compressive strength, energy dissipation density, and fragmentation characteristics related to the damage degree based on the Weibull distribution are theoretically studied and demonstrated by experiment. Uniaxial loading with diverse pre-loads is employed to make the concrete in varying damage degrees. The Split Hopkinson Pressure Bar (SHPB) is employed to investigate the damaged concrete's dynamic mechanical properties, energy evolution, and fracture characteristics. The experiment demonstrates the rationality of the theoretical study, the growth ratio of energy dissipation density, reduction rates of dynamic strength, and the average diameter of the fractured concrete all follow the Weibull distribution. The energy dissipation density and fragmentation degree of the damaged concrete under impact load increase with pre-load rise, while the dynamic strength and transmission energy are opposites.
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