Some observations about strain localisation and shear band formation in concrete samples

Strain localisation in concrete is reproduced by introducing a softening law coupled with damage in the stress-strain relationship and also considering coupling with damage. A quasi-static approach is developed, which requires initial imperfections to trigger off localisation. The model takes into account thermal, hygral and mechanical transient behaviour of concrete, through non-linear heat and mass transfer equations expressed as functions of relative humidity and temperature. The numerical code DAMAGE analyses the behaviour of viscoelastic damaged materials, under thermal flux and moisture diffusion, due to external forces, thermal loadings and imposed displacements or humidities.