Confinement enhanced damage-plasticity model for concrete

The purpose of this paper is to develop a confinement enhanced damage-plasticity model for concrete that can characterize the improvement of strength and ductility under high confining stress. The influence mechanisms of confinement in damage and plasticity sub-space are discussed separately. In the damage subspace, a confinement influence function considering the difference between uniaxial and multiaxial damage evolution is suggested based on the strain energy equivalence confinement. A confinement enhanced damage evolution model is established, which can capture the strength increase under high confining stress. In the plasticity subspace, a confinement enhanced phenomenological plasticity model, which includes equation of state of the spherical space, is provided to reproduce the high ductility at the principal stress direction under lateral confining stress. The simulated strength and stress-strain curves under active confinement agree well with the experimental results. Furthermore, the predicted three-dimensional ultimate stress points are consistent with the classic strength surface, validating good performance of the proposed model.