Influence of Size and Slenderness on Compressive Strain Softening of Confined and Unconfined Concrete

It is generally accepted that the postpeak strain-softening behavior of concrete in compression is a localized phenomenon that occurs mainly in the compression damage zone. Accurate quantification of the size and slenderness effects on the postpeak behavior of concrete, therefore, depends on the accurate quantification of the inelastic deformations that occur in the compression damage zone. In this study, a novel approach is proposed to separate the two inelastic deformation components, known as the localized crack deformation and the deformation caused by the inelastic strain in the compression damage zone, from experimental stress-strain curves. This new approach allows the utilization of existing test results in the published literature in the model development. Based on two comprehensive experimental databases of confined and unconfined concretes covering a wide range of concrete strengths, a constitutive model for predicting the strain-softening behavior of confined and unconfined concretes is proposed