Modification of Concrete Damaged Plasticity model. Part I: Modified plastic potential

In order to extend the Concrete Damaged Plasticity model [1], a modification of flow rule is considered. A new plastic potential is proposed. It takes into account the difference in behavior of concrete under compressive and tensile loading. In the present paper the proposed function is examined and compared to the original potential. Influence of parameters of the potential choice on the shape of its surface is analysed. Formulation and preliminary validation of the modified model is shown in the subsequent paper (Part II).