The dynamic strength of concrete and macroscopic temporal parameter characterized in fracture process

The structural-temporal approach based on the notion of incubation time is used for interpretation of strength behaviour of concrete in the fracture process. Temporal dependences of concrete under influence of steel spiral fiber, water, a scale level of fracture are evaluated by the incubation time criterion. Effect of more significant increase of strength in dynamic condition than static at growth percentage of fiber is explained by behaviour of the incubation time related with presence of defect in specimen. Numerical simulation of dynamic strength with different percentage of spiral fibers is given. Both size effect and scale effect for concrete samples subjected to impact loading are considered. Statistical nature of a size effect contrasts to a scale effect that is related to the definition of a spatio-temporal representative volume determining the fracture event on the given scale level.