Background:
Beam-to-column connections are essential for load transfer and seismic performance of moment-resisting frames. Given the limited repairability and post-earthquake rehabilitation of conventional steel moment frames, connections incorporating replaceable components have attracted attention as an approach to limiting damage and facilitating return to service. This study aims to investigate the seismic behavior of a column-tree connection equipped with a replaceable shear fuse located in the beam web region.

Methods:
The system was numerically analyzed in ABAQUS using nonlinear finite element modeling. The numerical model was validated against previous studies. Subsequently, the effects of geometric parameters, including the beam and column dimensions, fuse thickness, and stub beam length, on the hysteretic response, stiffness, load-carrying capacity, and cumulative dissipated energy were investigated. In addition, the weight of the proposed fuses was compared with the weight of flange and web splice plates assumed for a conventional beam splice.

Results:
The results showed that inelastic deformations were concentrated in the fuse member, while damage to the main connection components was limited. Increasing the fuse thickness from 15 to 20 mm increased the cumulative dissipated energy by approximately 20%. Among the investigated parameters, increasing the thickness of the main connection components and the fuse more strongly affected the load-carrying capacity, energy dissipation, and cyclic stability of the connection, whereas the effect of varying the stub beam length within the range was less pronounced. Furthermore, for fuse thicknesses of 15 and 20 mm, the total weight of the two fuses was 76% and 68% lower, respectively, than the combined weight of the four flange and web splice plates assumed for a conventional beam splice.

Conclusion:
Overall, by localizing damage within the fuse member, preserving the integrity of the main structural members, and significantly reducing the weight of the splice components, the proposed connection demonstrates promising potential for improving repairability and facilitating the post-earthquake return to service of steel moment-resisting frames. However, given the semi-rigid behavior of the connection, further studies aimed at increasing its stiffness could broaden the applicability of this system in steel structures.