Time-dependent fracture of cementitious materials

The response of cementitious materials is highly time dependent. On the one hand, it can lead to delayed collapse of structures fabricated of such materials. On the other hand, the time dependence is associated with the relaxation of peak stresses, which avoids, or postpones damage. A finite element formulation is presented for the analysis of the time-dependent cracking of cementitious materials. The constitutive law incorporates continuum plasticity and linear visco-elasticity. The former accounts for crack initiation and propagation, while the latter describes the bulk creep via an aging Maxwell chain. The cracking velocity dependence, which considers the additional viscous effect in the fracture process zone, is also included. This contribution to the cracking resistance regularises the localisation process and also introduces the correct time scale. The simple framework of the model allows the inclusion of other important phenomena in cementitious materials, such as stress-dependent hygral and thermal shrinkage.Architectur