Effects of loading rates on concrete double-K fracture parameters

The effects of loading rates on concrete double-K fracture parameters were investigated using central-notched split tension cubes, both experimentally and analytically. Four loading rates varying from 10−5/s to 10−2/s was adopted. Results showed that, with the increase of loading rates, the initiation fracture toughness linearly increased while the unstable fracture toughness varied by a first increase and a followed constant trend. It was also confirmed that double-K fracture model may be further extended to wider dynamic loading rates, such as seismic dynamic excitation. Finally, the models describing the loading rate influences on double-K fracture toughness parameters were developed.