Effect of the concrete cover thickness ratio on the post-yield stiffness of bridge columns with partially unbonded unstressed steel strands

Abstract A new self-centering concrete bridge column has been developed by the authors. The proposed uses unstressed partially unbonded seven-wire steel strands as elastic elements to reduce residual displacement of after a strong earthquake. This research aimed study effect cover thickness ratio on cyclic behavior column. Four large-scale specimens were tested using lateral loading. One was conventional other three columns with varying ratios. Test results showed that partial unbonding effectively prevented from yielding. post-yield stiffness ratios higher than did not significantly influence hysteretic energy dissipation and strain responses longitudinal reinforcement. However, it had significant impact ratio. tended be inversely proportional relationship between for preliminary design Based relationship, should exceed 5.1% achieve at least 5%, recommended in literature control