Abstract
It is well known that by confining a concrete element in two out of three mutually perpendicular directions the ultimate compressive strength of the element in the third direction increases considerably. In practice, confinement is usually passive, and provided by steel which induces compressive stresses in the element.
The present paper has investigated experimentally the deformational behaviour of concrete under passive confinement. In the experiment, concrete cast into a steel tube was subjected to axial compression. The parameters investigated were the strength of the concrete and the thickness of the steel tube. The experiment has clarified some of the most important characteristic features of concrete behaviour under passive confinement; these include elastic properties, ultimatestrength envelope, plastic strain, ductility and volumetric change.
