COHESIVE CRACK MODEL ING OF INFLUENCE OF SUDDEN CHANGES IN LOADING RATE ON CONCRETE FRACTURE

Abstract--The results of an experimental study of a sudden change in loading rate on the fracture behavior of normal- and high-strength concrete specimens of three different sizes are reported. Geometrically similar three-point bend specimens were subjected to either a sudden 1000-fold increase or a 10-fold decrease of the loading rate. It was observed that for a large increase of the loading rate, the post-peak softening can be reversed to hardening followed by a second peak of the stress-strain diagram. A sudden decrease of the loading rate initially causes asteeper softening slope of this diagram. The results are similar for normal and high strength concrete specimens. The viscoelastic cohesive crack model with the rate-dependent softening law is used to model the experimental results