Elasto–plastic modelling of confined concrete elements following MC90 equations

The present work considers the use of the elasto–plastic model in the analysis of concrete structures taking into account the confining effect. The MC90 equation for uniaxial compression is used in the model for the approximation of concrete behaviour in hardening and softening. The three dimensional state of stress in concrete is considered by the use of convenient yield conditions. The model is developed for Drucker–Prager and Ottosen yield criteria. The confinement effect is formulated by multiplying the derivative to the stress–strain law by a function of the intermediate principal stress. The stress–strain diagram obtained agrees with the stress–strain law defined in the MC90 for uniaxial compression in non-confined concrete. The numerical results show that the model approximates the experimental results obtained in cylinder specimens.