ELASTOPLASTIC CONSTITUTIVE MODELING OF GRANULAR ASSEMBLY

A triaxial elasto-plastic stress-strain relationship of a continuum solid derived from a base of granular assembly is presented. It shows a macroscopic material nonlinearity by considering the local geometric nonlinearity of the material on the microscopic level of the granular assembly. For a given strain increment causing both elastic and plastic strain increments in an assembly, the elastic strain is calculated by the known uniform strain theory of granular materials, and the corresponding plastic strain increment is computed from the mechanism resulting from the strain due to slip between particles. Responses of two construction materials, steel and concrete, predicted by the proposed constitutive law are illustrated. Some other well-known physical phenomena like dilatation, necking and the confinement effect are also addressed under various loading cases, including uniaxial tension and compression, cyclic loading, biaxial and triaxial loadings.