Seismic behavior of precast segmental UHPC bridge columns with replaceable external cover plates and internal dissipaters

A new earthquake resilient ultra-high-performance concrete (UHPC) bridge column was proposed and fabricated with precast segmental construction. The bottom segment was divided into two parts: core zone and four replaceable surrounding UHPC plates, between which replaceable dissipaters were employed. Rapid repair was completed with substitutions of damaged replaceable components, including UHPC plates and dissipaters, after an earthquake. Cyclic loading tests were conducted on three 1:3 scaled specimens and their corresponding repaired specimens. The research parameters included post-tensioning (PT) force level and usage of replaceable dissipaters. The test results showed that both the construction and repair times could be decreased owing to the use of proposed bridge column. The damage to replaceable dissipaters and cover plates was significant, but the damage to core concrete was minimal. The original repaired specimens presented displacement capacities of at least 5% and 4% drift, respectively. All specimens showed excellent self-centering and had less than 0.8% residual drift until failure. Two different failure modes were found: cover plate failure in lateral bending failure, which significantly reduced the lateral load, and dissipater coupler failure, which caused dissipaters to work inefficiently and decreased energy dissipation. Compared with the original specimens, which failed in the same failure mode, the repaired specimen had similar lateral load and displacement capacities, but a lower initial stiffness. All PT tendons were elastic and no yield or rupturing was found, but the stress loss was significant. The rotation of the bottom joint dominated the lateral deformation, and the contribution of joint sliding can be neglected.