STRAIN SOFTENING STRESS-STRAIN RELATIONS FOR CONCRETE.

Stress-strain relationship of concrete subjected to short-term, monotonically increasing uniaxial compressive loading is characterized by an increasing non-linearity with an increase in stress, having a peak stress (often termed failure or compressive strength of concrete) and a strain softening or a descending part. To predict the response of concrete subjected to monotonically increasing loading, several constitutive models have recently been proposed. In this paper, an orthotropic constitutive model is described. The model describes in a realistic and simple way the non-linear response including the strain softening. The parameters for the model were derived from the test results. These tests were designed to determine the descending part of the stress-strain curves of concrete subjected to multiaxial loading.