STUDY OF CONFINEMENT MODELS FOR HIGH-STRENGTH CONCRETE COLUMNS CONFINED BY HIGH-STRENGTH STEEL
The analysis of structural members requires an analytical model for the full stress-strain relationship of concrete in compression, both in confined and unconfined states. Many empirical confinement models for normal strength materials have been developed and documented in the literature during the last three decade. However, the models developed for normal strength material are not applicable to high-strength material. This paper reviews the various proposed stress-strain model for high-strength concrete materials confined by high-strength steel. The main objective of the study is to examine the capabilities of the various models available in literature to predict the actual experimental behavior of high-strength concrete columns confined by high-strength steel. The experimental data used are the results of the tests conducted by the author, involving testing of 18 short column specimens with 110 mm diameter circular section confined by 6 mm spirals or hoops made of wire rod reinforcement. The test variables include yield strength, type (spiral or hoops), spacing and volumetric ratio of confining steel. The resulting stress-strain curves from the tests are then compared with the various models available in the literature. It is shown from this study that there is no models which can accurately predict the complete behavior of high-strength concrete columns confined with high-strength steel.