Behavior of Confined High Strength Concrete Columns under Axial Compression

Abstract

An experimental study was carried out to investigate the behavior of high strength concrete short columns confined by circular spirals and square ties under monotonically increasing concentric compression. The test variables included volumetric ratio, spacing and yield strength of transverse reinforcement, longitudinal reinforcement ratio, lateral steel configuration, shape of cross section and concrete compressive strength. The effects of these variables on the uniaxial behavior of high strength concrete columns are presented and discussed The results indicate that more confinement is required in columns of high strength concrete than in columns of low strength concrete to achieve the desired post-peak deformability. The behavior of high strength concrete columns is characterized by the sudden spalling of concrete cover, leading to a loss of axial capacity. A comparative study of existing confinement models of high strength concrete columns was also conducted to assess their capabilities of predicting the actual test behavior. To this end, the stress-strain curves of the specimens tested in the present study were compared with the ones predicted by the various models. It is shown that Legeron & Paultre (2003) model estimates the actual experimental curves more closely as compared to the other models employed in the study.