The contribution presents simulations of fracture in concrete beams loaded in three-point bendingviadiscretemodel. Thesizeanddistributionofdiscreteunitsreflecttheconcreteheterogene- ity and together with properties of their contacts provide an internal length scale. Due to a random placement of the discrete units, the model mimics natural…
The contribution presents simulations of fracture in concrete beams loaded in three-point bendingviadiscretemodel. Thesizeanddistributionofdiscreteunitsreflecttheconcreteheterogene- ity and together with properties of their contacts provide an internal length scale. Due to a random placement of the discrete units, the model mimics natural randomness of material structure arising from its random heterogeneity. A second random component of the model considered is additional fluctuation of material parameters at contacts between the units. This randomness reflects variations in material properties due to mixing, drying, etc. and it is considered in a form of random field with its own internal length scale provided in a form of autocorrelation length. Bychangingtheratiosbetweentheautocorrelation length and the internal length arising from het- erogeneities, one can observe strong effects of this ratio on structural strength when cracks propagate from smooth surface. For deeply notched beams, the spatial strength fluctuations only affects the variance of the peak load and no significant effect observed on its mean value. The described depen- dency of structural strength on the ratio between the two characteristic lengths is demonstrated and elucidated.