Numerical Concrete Applied to Investigative Size Effect and Stability of Crack Propagation

In this paper the numerical concrete approach is used to simulate crack formation and crack propagation in uniaxial tensile concrete specimens. In this model concrete is represented by three principal phases, each having its own mechanical properties. The mechanical properties of each phase are assumed to be statistical variables following Gauss's distributions. The influence of the length of the specimen on the global (macroscopic) mechanical properties is studied. It has been found that the macroscopic tensile strength decreases sligthly as the length of the specimen increases. The mean value of the tensile strength of the weakest phase i.e. interface controls the global tensile strength of the composite system. This analysis shows that the ductility of the composite material is strongly dependent on the strength differences of the phases forming the system. Remarkable damage occurs all over the composite system prior to the formation of a narrow band of real cracks. The energy dissipated by microcracking before the maximum load is reached (pre-peak damage energy) increases with the length of the specimen. After a certain critical length of the specimen, the fracture process can not be controlled any more. The system then is unstable. 619 years ago we developed an ~ ..... ,...., ... ..,,......... approach, concrete (Roelfstra et (1985). This "'"""'""'·~·~""""' allows us to .... 'U" ........ ..,,,_,._,"",~""' structure the interface consideration is to investigate, at size concrete '-"IJ'"'""'-'-JllL .. ...,JL ... ..., subjected to a .. u ............. ,., ......... ... ....,..., ............. .., .. ...,. the internal structure concrete is represented by a "-''"''"' ................... ,."'-4 .... consisting different phases. properties of the ~ ......... ~ ... ...., ...... v .......... ...,....,..., as well as distribution in a given volume can be adjusted to ............... ..., ...... ...,...