Behavior of long confined concrete column

The behavior of concrete columns confined by fiber reinforced plastic/polymer (FRP) depends on several parameters, including concrete strength, types of fibers, volume and orientation of fiber in the jacket, jacket thickness and shape of cross section, length-to-diameter (slenderness) ratio of the column. In this paper, the behavior of long concrete columns confined by means of proper plastic tube is investigated including failure mechanisms and subsequently their failure mode with theoretical model for calculation of the column capacity. The influence of column slenderness ratio on their axial load capacity, axial strains, and radial strains is also investigated. The experimental program was classified into three different groups with slenderness ratios from 9 to 18. Test results show that, utilizing plastic tube for confinement significantly influences the failure mechanisms of concrete columns. Results also show that the stiffness of the tested long confined concrete columns specimens increases as slenderness ratio decreases.