Abstract
It is verified that the enhanced microplane concrete model can predict well the experimentally obtained constitutive relations for concrete reported in the literature, covering various stress conditions. Extracting the invariants of the stress and strain tensors from the analytical responses obtained by the present model, one can reproduce the experimental relations in terms of the invariants. The present model can also predict the stiffnesses for reversible nonlinear elastic response during unloading and reloading, which are obtained by applying small loading pulses. Analysis of concrete confined by a steel tube confirms that the present model can describe the passive confinement effect well. Examination of the microplane responses in each analysis explains the load-carrying mechanisms in concrete in terms of the responses on the microplanes.
