Seismic behaviors of self-centering steel structural joints with phased energy dissipation

To reduce residual deformation in steel moment-resisting frames under seismic actions and facilitate rapid postearthquake functionality recovery, a self-centering steel structural joint with phased energy dissipation was proposed. This joint achieves self-centering capability through the restorative force provided by prestressing steel strands. Additionally, it employs two energy dissipation mechanisms, namely frictional sliding between the friction plate and the T-stub web and the plastic deformation of the T-stub itself, at different stages to dissipate seismic energy. This approach enables effective phased energy dissipation. Cyclic loading tests were conducted on four full-scale specimens with varying initial prestressing forces of steel strands and bolt pretension. This study obtained seismic performance parameters of the specimens, including hysteretic curves, skeleton curves, stiffness degradation, and energy dissipation. Furthermore, the phased energy dissipation mechanisms of these specimens at different loading stages were investigated. It was found that the loading process of the specimens could be divided into three stages: elastic stage, sliding stage, and strengthening stage. During the elastic stage, the specimens remained closed, with all components in an elastic state. As the loading progressed to the sliding stage, the specimens dissipated energy through frictional sliding between the friction plate and the T-stub web. In the strengthening stage, the primary energy dissipation mechanism of the specimens was the plastic deformation of the T-stub. Moreover, the initial prestressing force of the steel strands had significant influence on the bending capacity and self-centering capability, while the bolt pretension mainly affected the energy dissipation capacity and bending capacity of the specimens.