Abstract:A prominent variety of stress-strain relationships are displayed for concrete under different stress paths or complex loading conditions. A stress-strain relationship similar to the elastic deformation of the hysteresis loops is observed under a small amplitude of deviatoric stress. The stress-strain relationship and failure behavior are associated with the value of hydrostatic pressure under different stress paths. The prominent of anisotropic behavior is weakening with increasing the value of hydrostatic pressure. In addition, the failure mechanisms and the corresponding hardening damage processes of compression and tension, are all different. There are three hardening damage types, namely the compressive hardening damage, tensile hardening damage and the mixing hardening damage. A new model is proposed by revising Hsieh model at three aspects:(1) There is not plastic deformation for small amplitude of deviatoric stress under cyclic loading conditions, while there is always plastic deformation predicted by Hsieh model. The frame of bounding surface model is adopted and a pure elastic zone is established in the bounding surface. The assumption that the initial yield surface and subsequent critical yield surface is similar in geometry is adopted. (2) A generalized constitutive model is proposed by transformed stress method based on generalized nonlinear strength criterion. The hydrostatic pressure effect of meridian plane and deviatoric plane for different stress paths can be reasonably considered by adopting the proposed model. A problem of singular stress point on boundary surface is avoided by adopting the TS method. (3) Hardening parameter expressions based on two kinds of load in tension and compression damage pattern are proposed and can be respectively adopted to describe the strain softening and strength degradation behavior generated by loading process. The proposed model can be used to describe the general stress-strain relationship of concrete based on a variety of loading tests simulation.