Abstract
For reduction in steel weight and duration of reinforcement work, continuous hoops can be used as the lateral reinforcement of reinforced concrete columns. In the present study, seismic tests were carried out in order to verify the earthquake resistance of the columns reinforced with continuous hoops. According to KCI 2012, the column specimens were designed with high strength SD600 and SD500 steel bars for the longitudinal and lateral reinforcements, respectively. The test results showed that the load-carrying capacity and deformation capacity of the column specimens confined with various details of continuous hoops were comparable to those of the column confined with conventional tie hoops and crossties with seismic hooks. In addition, a close investigation on the longitudinal bar buckling occurring at the plastic hinges of the columns showed that sway and/or non-sway buckling modes of longitudinal bars can be significantly influenced by the spacing and diameter of lateral reinforcement. In the present study, the lateral reinforcement spacing restraining premature longitudinal bar buckling was proposed and the proposed method was compared with the test results. Based on the proposed method, the requirements on the lateral reinforcement spacing of columns specified in KCI 2012 and ACI 318-11 were examined.