Investigation into Lubliner yield criterion of concrete for 3D simulation

A class of widely used plastic-damage models for concrete employ the Lubliner yield criterion, whose properties in triaxial stress states have not received due attention. This paper intends to provide a thorough investigation into this strength theory for its application in 3D simulation of concrete structures. Its algebraic formulation and geometric representation are analyzed with a particular perspective on the similarity in form between the yield conditions in triaxial compression and other stress states, from which it is found that there is a strong dependence of triaxial tensile strength on the compressive cohesion and strength increase in triaxial compression fails to be described appropriately. Effective calibration methods are proposed for concrete under uniform and non-uniform confinement respectively to take into account both strength increase and strength ratio.