Experimental and analytical studies on the compressive behaviors of a 3D-printed sand mold-cast S-CN connector in modular steel buildings

Steel modular construction offers advantages in speed, cost, and sustainability, but its adoption is constrained by connection efficiency. This study introduces the Samsung Connection Node (S-CN), a novel cast-steel connector fabricated using 3D-printed sand molds. Full-scale tests on roof nodes, floor nodes, the connector, and a beam–column assembly under axial compression were conducted, supported by finite element (FE) and analytical studies. Roof nodes carried 10% higher loads than floor nodes, while connector strength was governed by tie plate deformation and local buckling. Beam restraint improved load utilization, producing higher uniformity of strain. Code-based predictions (AISC 360-16 EN 1993-1-1) provided conservative agreement with experiments and FE. A mechanics-based model clarified that rim bearing controls global capacity, while yield-line mechanisms explain local deformation. Parametric studies highlighted the strong influence of node thickness and adverse effects of large openings or excessive column height. Supplementary FE analyses under combined axial–moment loading indicated a stable numerical response of the connector and suggested robustness under service-level eccentricities. A nonlinear pushover analysis of a corner subassembly suggested a ductility ratio of 7.5 with drift ratios below the ASCE 7 and Eurocode 8 near-collapse limits in the numerical model; these seismic-related findings are preliminary and require future experimental validation. • Novel 3D-printed sand mold S-CN connector for modular steel construction. • Full-scale axial compression tests on nodes, connector, and subassembly. • Mechanics-based model explains connector failure beyond code provisions. • FE analyses under combined axial–moment loading show stable numerical response. • Pushover analysis suggests good numerical ductility and code-compliant drifts.