Concrete in compression: a plasticity theory with a novel hardening law

This paper deals with the modelling of the behaviour of plain concrete in triaxial compression using the theory of plasticity. The aim is to model the load resistance and the deformation capacity in uniaxial, biaxial and triaxial compression by means of few parameters, which can be determined easily. A novel hardening law based on a non-associated flow rule and the volumetric plastic strain as hardening parameter is combined with a yield surface proposed by Men etrey and William (1995). The novel hardening and softening law differs from a classic strain-hardening law, as instead of the length of the plastic strain vector only the volumetric component of the latter is used as a hardening parameter. Thus, the non-linearity of the plastic potential is utilized to describe the influence of multiaxial compression on the deformation capacity and no additional ductility measure is required. The implementation and calibration of the novel hardening law are discussed. The prediction of the model is compared to results of uniaxial, biaxial and triaxial compression tests. It is shown that with one set of calibration parameters a good prediction of the load resistance and the deformation capacity for all three types of compression tests can be achieved.