Cyclic loading test for reinforced concrete columns with continuous rectangular and polygonal hoops

A re-bar fabrication method using continuously wound rectangular or polygonal ties (or continuous hoops) was developed to enhance constructability and economy of reinforced concrete columns. In the present study, cyclic loading tests were performed to investigate the structural performance of the columns with continuous hoops. The test parameters were the shape, spacing, and bar diameter of the continuous hoops, and the spacing between the longitudinal bars and the hoops. The load-carrying capacity, deformation capacity, and failure mode of the specimens were directly compared with those of a column with conventional ties. On the basis of the test results, the effects of the continuous hoops were evaluated. Further, requirements for the vertical spacing of transverse reinforcement were studied to restrain the post-yield buckling of longitudinal bars in the plastic hinge zone.