Damage-Controlled Column-Tree Moment Connections Using Replaceable Fuse Plates: Experimental and Numerical Evaluation

Improving the seismic performance and post-earthquake reparability of steel moment connections requires designs that concentrate inelastic deformation in replaceable components while protecting primary structural members. Column-tree connections, which combine shop-welded beam stubs with field-bolted beam spans, offer a potential solution. However, experimental evidence remains limited for configurations incorporating conventional rectangular fuse plates. This study investigates their cyclic performance through eight full-scale tests conducted according to the AISC seismic loading protocol, complemented by calibrated finite element simulations. The experimental variables included the number of flange bolts, cover plate thickness, and beam stub length. All specimens sustained a drift ratio of 4% and exceeded 80% of the nominal beam plastic moment capacity. The experimental results revealed that the influence of bolt quantity on connection strength and energy dissipation depends on cover plate thickness, while beam stub length also affects the cyclic response. Inelastic deformation was predominantly concentrated in the replaceable cover plates, with no visible fracture or local buckling observed in the primary structural members. Energy dissipation involved frictional sliding during the initial response and localized cover plate yielding at larger drift demands, although the individual contributions of these mechanisms were not quantified separately. The numerical models reproduced the principal deformation mechanisms and overall hysteretic behavior, although discrepancies remained in stiffness and peak strength. The findings provide experimental evidence supporting the feasibility of damage-controlled column-tree moment connections incorporating conventional replaceable cover plates, while highlighting the influence of connection detailing on cyclic performance and post-earthquake reparability.