Behavior of Small-Scale Concrete Columns Confined by 3D Printed Reinforcing Cages

摘要

In recent years new technologies have been developing for use in large-scale civil infrastructure design and construction. The complexity of steel reinforcement configurations designed to confine concrete columns has previously been limited by traditional construction techniques. Additive manufacturing provides new opportunities to create innovative designs. Sixteen transverse reinforcement orientations were included in this study, half of which were based on traditional layouts, while the others were innovatively designed by the researchers. The reinforcement cages were 3D printed using a strong and flexible plastic material, placed inside of 3x12 in. column molds, and filled with lightweight grout. Each design included eight longitudinal bars arranged around a circular base plate and two thin sleeves encasing the top and bottom 3 in. of the longitudinal bars. The transverse reinforcement configurations were added to the remaining 6 in. design area between the top and bottom sleeves. After casting and curing the specimens, the design groups were subjected to constant axial load until failure and their confining behaviors were monitored during loading. In summary, toughness, ductility, and load capacity generally increased as the spacing of transverse reinforcement used to confine the core decreased. Conversely, cages designed with reinforcement inside and around the core typically had an opposite reaction; as the spacing of transverse reinforcement decreased, the ductility and toughness also decreased. However, the most ductile and toughest designs were the cages that included smaller volumes of transverse reinforcement along with reinforcement inside of the core. Test results show that some innovative reinforcement designs perform better than the traditional configurations that are still being used to confine concrete columns.