PERFORMANCE OF SQUARE REINFORCED CONCRETE COLUMNS CONFINED WITH INNOVATIVE CONFINING SYSTEM UNDER AXIAL COMPRESSION

Abstract

Several structural failures occur in the columndue to the lack of confinement. The circular column is not popular for regular buildings. The use of circular spiral is only familiar tothe circular column. Many design engineers usesquare columns with hoops and cross tiesas confinement. As far as the authors’ knowledge, therewasonly a study carried out on square columnswith circular spirals as confinement. For this reason, the authors propose and introduce a new type of innovative confinement system for square columns using square spiralsas confinement and a combination thereof, which has never been carried out in the previous studies. No code’s provision is also applicable tothis type of confinement.This research was conducted to investigate the performance of each of these new confinement systems as a promising option in the future instead of the traditional confinement. To achieve the objective of the research, a two-phase study was conducted. The first phasewas to analyze the potential, design, formation, and assemblyof the new confinement systemconsisting of a combination of square and circular spirals (SPIL), a combination of octagonal and square spirals (SS8I), an interlocking among square spirals (SPIP), and a plain concrete specimen (PC) as a benchmark. The second phasewas an experimental program that involvesa mix-designof the concrete, preparation of the column specimens with various confinement systems, and the compression tests of the column specimens using a 3500-kN UTM. The test results indicate that the SPIP specimen has higher initial stiffness, peak stress, and strain ductility compared with others.