Deterministic size effect in concrete structures with account for chemo-mechanical loading

The work presented here is focused on examining the size effect in concrete structures subjected to different loading conditions, which include a chemo-mechanical interaction. The study involves extensive three dimensional finite element simulations, which incorporate a constitutive law with embedded discontinuity for tracing the propagation of damage pattern. The analysis deals with various mechanical scenarios that incorporate both a cohesive and frictional damage mechanism, as well as the effects of degradation of concrete triggered by continuing alkali-silica reaction (ASR). In the latter case, a chemo-plasticity framework is employed. The first set of simulations provides a deterministic assessment of the size effect in a series of three-point bending tests as well as compression tests. For continuing ASR, it is demonstrated that, by increasing the size of the structure, a spontaneous failure may occur under a sustained load. The numerical examples given here clearly show that the size effect is associated with propagation of localized damage whose rate is controlled by a suitably defined ‘characteristic length’.