In this article the compressive mechanical behaviour of quasi‐brittle materials is analysed by means of experimental tests and by using an ad hoc algorithm for numerical simulations based on the Pseudo‐traction and the Boundary‐element methods. The experimental analysis is carried out on specimens with three different size‐scales, three different values of slenderness and two boundary conditions. The numerical analysis was carried out by taking into account the initial random crack distribution, considering the mutual crack interaction, the crack–boundary interaction and the internal friction between the faces of the cracks. The numerical results, in good agreement with the experimental data, highlight the characteristic strain‐softening behaviour of quasi‐brittle materials, and the influence of size‐scale and slenderness on the structural response. By observing the evolution of the crack patterns, it is possible to emphasize, both experimentally and numerically, the transition from crushing to splitting collapse by increasing the specimen slenderness, as well as the transition from ductile to brittle behaviour by increasing the specimen size‐scale.

In the present paper the compressive mechanical behaviour of quasi-brittle materials is analysed by means of experimental tests and by using an ad hoc boundary element algorithm for the numerical simulations. The experimental analysis is carried out on specimens with three sizescales, three different slendernesses and two boundary conditions. The numerical analysis was carried out by taking into account the initial random crack distribution, considering the mutual interaction, the crackboundary interaction and the internal friction between the faces of the cracks. The numerical simulations, in good agreement with the experimental results, highlight the characteristic strain-softening behaviour of quasibrittle materials, and the influence of size-scale and slenderness on the structural response. By observing the evolution of the crack patterns, it is possible to emphasize, both experimentally and numerically, the transition from crashing collapse to splitting collapse by increasing the specimen slenderness, as well as the transition from ductile to brittle behaviour by increasing the specimen size-scale.

Strain softening of concrete in uniaxial compression critically m1:1uenc:;es way concrete structures are designed. Yet it is not explicitly included design methodologies. This may be partly due to the fact that it is difficult to obtain post-peak pesponse especially for higher strength concrete and that the response depends also on the geometry of specimens, boundary conditions, and testing machine parameters. To delineate the influence of various parameters, a round robin test program is being persued by .L-..JL.LJ.._,,.. Committee 148 SSC 'Strain Softening of Concrete.' Results obtained from one laboratory participating in this round robin test program are discussed. discussion includes methods to obtain the strain softening response of concrete in compression. The effects that the platens, lubrication between platens specimen, specimen size, and measurement gage length have on results are explored.