In this project, it is intended to study the theoretical basis of strain-softening plasticity in modeling deformational and failure behaviors of concrete materials in the post-fracture range; to develop a comprehensive three-dimensional stress-strain relation for concrete based on the theoretical studies covering a wide range of stress conditions including the post-fracture softening behavior; to implement the model into a three-dimensional nonlinear finite element analysis program, and to verify the program by solving some boundary value problems of practical significance. In this study, special emphasis will be placed on strain-softening modeling of concrete material in the post-fracture range, within the general framework of strain-space formulation of plasticity based on Ilyushin's postulate and the fracture theory. A more general strain-space formulation, which accounts for both plastic and fracturing of concrete, will be developed.
