Abstract
This thesis describes theoretical and experimental investigations into the behaviour of concrete under uniaxial and multiaxial stresses. A simple theoretical approach is used to obtain relationships between the properties of concrete and those of its constituents for different aggregate volume concentrations. It is shown that the theory is in general agreement with the results obtained on a range of concretes tested in uniaxial compression. A stochastic model, based on progressive failure is used to relate the uniaxial compressive strength of concrete to the water/cement ratio, aggregate grading and aggregate volume concentration. It is shown that the deduced expression may, for certain conditions, be simplified to give Abrams law. Some experimental results are given which enable the constants in the deduced expression to be obtained. Results are given of an investigation into the influence of mix proportions and specimen age on the strength and stress-strain behaviour of concrete in triaxial compression, extension and tension plus biaxial compression. A general failure criterion is given in which the major principal stress at failure is expressed as a simple fuction of minor principal stress, uniaxial compressive strength and estimated uniaxial tensile strength. This general failure criterion is shown to be in reasonable agreement with the results obtained on a range of conventional concretes.