Compressive Softening Model for Concrete

A strain‐space‐based plasticity model is proposed to represent the softening as well as hardening behavior of concrete under low confining pressure. Unlike the stress‐space plasticity theory based on the Drucker's postulate, the strain‐space plasticity theory based on the Il'yushin's postulate can give a clear distinction of loading, neutral loading, and unloading. The general strain‐space formulation is presented in some detail by introducing the Lade type of loading function F and a new plastic potential function G defined in strain space. The incremental stress‐strain relation is given in a tensorial form. Using the experimental data available from triaxial compression tests, the model parameters are determined, and model simulation is performed to demonstrate the model capability. It is confirmed that the proposed model can sufficiently predict the softening as well as hardening behavior of concrete materials under the low confining pressure.