Abstract
The physical meaning of the fracture energy (G_f) is an energy release rate for a non-elastic body. The Gf is a sum of elastic and non-elastic energy release rates and is an applicable parameter to one instead of the J-integral. Experiments were conducted in order to investigate the propriety of the above considerations. Then the G_f was determined by means of measuring a repeated load-displacement curve with a notched plain concrete beam under three-point bending. As the results the following inspects were derived. The G_f agrees reasonably with the critical J-integral at the beginning of extension of a main crack, but during its stable growth the G_f increases monotonously with the increase of extension area.
