Forces Restraining Buckling of Reinforcing Bars

Abstract

Reinforced concrete columns in existing buildings that were not designed to resist seismic loading have a widely transverse reinforcement and there is a chance that the longitudinal reinforcement is buckled and then covering concrete is spalled off in the event of a severe earthquake. Therefore, the columns should be retrofitted by restraining the buckling of reinforcing bars. This study tested the compressive strength of reinforcing bars with horizontal force restraining the buckling. The specimens are grade SD40 and have diameters of 16 mm, 20 mm and 25 mm. The test results show that the restraining force increases after the yield point and increases progressively with increasing compressive strain. For reinforcing bar with large diameter, greater restraining force is required. The results of this test can be applied to the design of column retrofit in the future study.