Seismic Performance of a Novel Prefabricated Concrete-Filled Steel Tubular Column–Steel Beam Joint with Replaceable Components

Conventional concrete-filled steel tubular (CFST) column–steel beam joints are susceptible to irreversible plastic damage at beam ends, column walls, and joint cores during strong earthquakes, complicating post-earthquake repair. This study proposes a novel fully bolted prefabricated joint with replaceable double-channel energy-dissipating components to improve damage control and repairability. Preferential yielding, plastic deformation, and local buckling of the channels dissipate seismic energy, limiting damage to the primary members and joint core. A detailed finite element model was developed based on existing experimental data to assess the joint’s seismic performance. Plastic strain concentrated in the channels, while the main steel beam, CFST column, and steel sleeve sustained limited damage. The load-transfer analysis clarified the roles of the channel flanges and webs in transferring bending-induced axial forces and shear, respectively. Compared with a monolithic external-diaphragm joint, the proposed joint localized damage more effectively within the replaceable channels, with 20.6% higher initial stiffness and approximately 40% greater total energy dissipation. Increasing channel thickness from 4 to 10 mm increased peak load, initial stiffness, displacement ductility factor, and cumulative energy dissipation by 27.7%, 33.0%, 18.0%, and 69.8%, respectively. Increasing channel length from 360 to 630 mm reduced peak load and initial stiffness by 21.8% and 42.4%, respectively, while increasing ultimate displacement by 43.5%; cumulative energy dissipation peaked at 540 mm. Increasing the axial compression ratio from 0.1 to 0.4 had little effect on peak load but reduced ultimate displacement and cumulative energy dissipation by 10.2% and 23.0%, respectively. Within the investigated joint dimensions and parameter ranges, a channel thickness of 8 mm and an axial compression ratio of 0.1–0.2 are recommended. Larger slip displacement intensified hysteretic pinching and reduced load-bearing capacity and energy dissipation. A simplified yield-load equation was developed, with relative errors within 10% compared with the results of 15 finite element models. A channel length of 540 mm is preferred when prioritizing energy dissipation and deformation capacity, whereas 450 mm is preferred when prioritizing strength and initial stiffness.