ROLE OF EXPANSION ON MECHANICAL-BEHAVIOR OF CONCRETE

The collective experimental evidence from standard uniaxial, biaxial, and triaxial tests of plain concrete is examined to identify the essen tial governing state variables for the benefit of three-dimensional co nstitutive modeling of the material. It is shown that the volumetric e xpansion that develops in mechanically loaded concrete due to progress ive microcracking is an important measure of the extent of damage in t he material microstructure, and can be used to consistently estimate t he changes effected on the resistance of concrete as damage accumulate s. Within this framework, the degree of restraint against expansion, s uch as is provided by arbitrary boundary conditions, can be used to co mpletely determine the residual strength and deformability of concrete under these conditions. These concepts provide the tools for the deve lopment of a simple but general constitutive model for concrete and of fer an opportunity for unification of the existing interpretations of various aspects of the observed mechanical response of concrete. Examp le problems are included demonstrating that with a limited number of p hysical variables it is possible to reproduce the sensitivities of an array of benchmark experiments.