A SIMPLE METHOD FOR DETERMINING MATERIAL FRACTURE PARAMETERS FROM PEAK LOADS

A simple method (peak load method) for determining material fracture p arameters K-Ic(S) and CTODc of the two-parameter fracture model is pro posed in this paper. To apply this method for values of K-Ic(S), and C TODc of a concrete, one only needs to measure peak loads of three or m ore distinctive specimens. For specimens of the same geometry, they ma y be the same in size but different in notch length, or the same in no tch length but different in size. A detailed procedure of calculating K-Ic(S) and CTODc from peak loads is provided. This method is verified by an experimental program, and confirmed by analysis of some existin g data of three-point bend beam tests. It is found that the values of K-Ic(S) and CTODc obtained from the split-tension cylinders with the p eak load method closely match the values of K-Ic(S) and CTODc obtained from the three-point bend beams with either the peak load method or t he compliance method, previously recommended by RILEM. The successful use of split-tension cylinders reveals great potential of the peak loa d method in testing specimens cored from an existing structure so as t o evaluate performance of the structure from the viewpoint of fracture mechanics.