Effects of unbonded prestressing steel tendons and slit dampers on the seismic behavior of precast concrete beam-column joints

This article proposes a novel precast concrete (PC) beam–column joint that uses prestressing steel reinforcement tendons and external steel slit dampers (SSDs) to provide self-centering and energy dissipation capabilities. The SSDs are steel plates cut to a desired shape installed under the beam ends to control their yield through energy dissipation. Three exterior beam–column joint specimens were investigated through quasi-static reversed cyclic loading tests. The specimens included a PC beam–column joint with only an SSD and two PC beam–column joint specimens using unbonded prestressing steel tendons (two in one specimen and four in the other) and an SSD. A fiber-based model using the software Ruaumoko and a code-based design were developed and validated against the experimental results. The test results showed that without the tendon, the specimen was significantly damaged, whereas using unbonded prestressing steel tendons with an SSD endowed the beam–column joint with a higher lateral load capacity of up to 40%. In addition, the ductility improved significantly up to 1.88 times. The developed model and the code-based design were in excellent agreement with the experimental results. Overall, this innovative connection type offers an alternative for seismic-resistant PC structures, and its design enables easy repair after an earthquake.