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

Several structural failures occur in the column due to the lack of confinement. The circular column is not popular for regular buildings. The use of circular spiral is only familiar to the circular column. Many design engineers use square columns with hoops and cross ties as confinement. As far as the authors' knowledge, there was only a study carried out on square columns with circular spirals as confinement. For this reason, the authors propose and introduce a new type of innovative confinement system for square columns using square spirals as confinement and a combination thereof, which has never been carried out in the previous studies. No code's provision is also applicable to this 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 phase was to analyze the potential, design, formation, and assembly of the new confinement system consisting 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 phase was an experimental program that involves a mix-design of 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.