Discrete Element simulation of concrete fracture and crack evolution

Concrete fracture phenomena and their statistically varying character are investigated in this work. It is the complex processes of failure mechanisms, crack propagation and damage evolution which are specifically investigated rather than to reach a certain maximum load or to investigate the concrete behaviour within a range of safe working loads. In order to go into this matter, a two-dimensional numerical simulation based on the Discrete Element Method (DEM) is used for the analysis of concrete behaviour under compression load. Crack patterns, crack initiation and damage evolution are analysed. The cracks are discrete just as in real laboratory experiments. The cracks arise due to the interaction of the concrete particle elements and without the predefinition of any crack zones or crack elements. The numerically generated concrete specimens differ in statistically varying positions of the single particles. This corresponds to different specimens of the same batch in real laboratory experiments. In the simulation, different particle generations with the same parameters are calculated. Furthermore, exactly the same particle generations are calculated until ultimate load and failure several times - under lower and under higher loading velocities.