Abstract
A new constitutive model for concrete under multi axial stresses is proposed in relation to the nonlinear stress analysis of the concrete structure by the FEM. An anisotropic formulation is shown by introducing parameters concerning Young's modulus and Poisson's ratio so as to satisfy the reciprocal theorem. Linear relationship of the incremental stress and strain is used by the assumption that the axes of anisotropy are chosen in the principal stress directions and the parameters are represented as the function of the strains in those directions. The fracture condition of the mathematical model consists of the tension cut-off and the octahedral shear failure criteria. The stress-strain relationship of the biaxial compression tests is discussed to determine the values of parameters. And the numerical method is applied to the two ultimate pressure tests on the scaled model prestressed concrete pressure vessels to discuss the compatibility of the measured and calculated data.
