Méthode expérimentale de détermination de l'énergie de rupture des bétons ordinaires

The aim of this paper is to determine the failure energy of ordinary concretes. This energy is considered as an intrinsic characteristic of the cracked material. RILEM recommendations related to three-point bending tests on notched beams have been studied and applied. This experimental model needs appropriate equipment working in controlled displacement mode. The controlled force test is generally unsteady. The result is that tensile curves (σ-w) are hardly achieved until the end of the test. In numerical modelling of the failure, it is precisely the descending branch of the curve (σ-w) which characterises the crack material because the stress reduces, whereas the crack opening increases (strain-softening). The tests carried out are failure tensile tests in mode I. The results obtained are ultimate loads of failure related to three-point bending notched specimens. A prediction method of failure energy based on intensity factor design of critical stress has been used. The latter is the result of experimental models interpolation in the field of failure mechanics. The results obtained are satisfactory and will allow the researchers who wish to simulate the crack by finite element modelling to use these results. For this purpose, experimental curves (σ-w) could be approximated by using linear, two-linear or exponential straight line providing that this failure energy remains steady.