<p>This study presents a bolted end-plate connection detail for weak-axis beam-to-column joints, incorporating a T-shaped adapter to improve constructability and facilitate field installation. A total of six finite element (FE) models were developed in Ansys to systematically evaluate the seismic performance of the proposed connection by varying the thicknesses of the T-shaped adapter flange, end-plate, and continuity plates. The numerical modeling approach was validated against available experimental results from the literature for both strong-axis and weak-axis moment connections to ensure reliability under cyclic loading conditions. Following the validation process, a parametric investigation was conducted to determine the component dimensions required for the proposed connection to satisfy the seismic provisions of ANSI/AISC 341 − 16 for Special Moment Frames (SMFs). The results were assessed in terms of hysteretic behavior, ductility, joint stiffness classification, plastic deformation, and bolt force demand. The findings indicate that the proposed configuration, especially in stiffer models (M1 and M2), exhibited stable cyclic response and significant plastic rotation capacity, successfully meeting the 4% story drift angle and 0.80<i>M</i>_<i>p</i> moment capacity requirements. Ductility coefficients were found to range between 2.11 and 2.85, validating the energy dissipation potential of the connection detail. The stiffer models achieved a rigid joint classification and effectively confined plastic deformations primarily to the beam flanges, validating the potential applicability of the T-adapter detail in seismic design scenarios. The results also suggest that existing design provisions for strong-axis end-plate connections may provide a reasonable benchmark for proportioning this connection type. The validity of this observation was further verified through additional numerical analyses involving beams with substantially different depths and flange proportions.</p>