DISCRETE CONFINEMENT BY METAL SHEET STRIPS ON CONCRETE COLUMNS UNDER AXIAL COMPRESSION
Keywords:
Strengthening, Concrete column, Metal sheet, Discrete confinementAbstract
This paper investigated the axial compressive strength of concrete columns discretely confined with metal sheet strips. Totally 54 cylindrical columns, in size of 15 cm in diameter and 75 cm in height, with various patterns of sheet confinement, were experimentally studied under uniaxial compression. The varying factors included the width of metal sheet strips, number of used strips, and number of applied layers. The experimental results revealed that axial strength could be improved by means of discrete confinement depending on the amount of applied metal sheet in terms of confinement area and confinement volume. The uniaxial compressive response was improved both in terms of strength and ductility when more strips and/or more layers of the metal sheet were applied. Compared to the full confinement using one piece of metal sheet, the discretely confined columns did not show any local failure or wrinkles of the metal sheet before failure. The wrinkles associated with bi-axial action in metal sheet was shown to be relieved with the discrete confinement technique. The failure mode of discretely confined columns in this study started with the rupture of the metal sheet jacket and was followed by the crushing of the inner core concrete. The equation of gained confinement effectiveness and effective confining stress of the studied columns were compared with the recent numerical study.