Behavior of Short Reinforced Concrete Column Elements with Buckling-Resistant Antispring-Clad Reinforcing Bars (BRASR) under Axial Compression

In this study, the buckling-resistant antispring-clad reinforcing bar (BRASR) for improving the performance of the longitudinal reinforcing bars embedded in concrete columns is presented. BRASR is formed using a set of springs wound in opposing directions and clad on the rebar with a groutable gap. In an experimental program, the performance of the BRASR is compared with the conventional longitudinal rebar in a typical column reinforcement cage. Short reinforced concrete (RC) square column elements with parametric variations in the ratio of tie spacing to the diameter of longitudinal bar (s/d) and the influence of tie restraint are evaluated under applied uniaxial compression. RC columns with spring clad bars exhibited improved buckling resistance of the rebar, which enhances the load capacity and the ultimate displacement ductility. In columns with BRASR, there is an increase in the strain energy and the resistance of the concrete core is improved. While the conventional specimens failed by a decrease in load resistance, the BRASR specimens showed better post-peak behavior and ductility. (C) 2019 American Society of Civil Engineers.