Nonlinear Behavior of I-Shaped Reduced Beam-to-H-Shaped Column Weak Axis Moment Connections Under Cyclic Loading

This study explores the influence of flange connection plate geometry on the structural performance of reduced I-shaped beam-to-weak axis H-shaped column moment-resisting connections subjected to cyclic loading. Four connection types were primarily designed in accordance with reduced beam section (RBS) requirements, utilizing an I-shaped adapter welded to both the web and flanges of the column via complete joint penetration groove welds. The length of the adapter’s outstanding section varied among the connections, with one model shifting the RBS closer to the column to evaluate the effects of plastic hinge relocation. Three-dimensional finite element models were developed using solid elements to simulate each connection type under cyclic loading. All models satisfied the flexural resistance requirements for special moment frames, confirming their ability to resist moments at the column face. Findings demonstrated that extending the flange connection plate beyond the column flange reduced plastic demands at the beam flange edge, while incorporating a circular curve in the extended portion significantly decreased the plastic equivalent strain and rupture index, reducing the potential for crack propagation at the beam ends. Moreover, minimal risk of cracking was observed at the adapter-to-beam connection when the adapter plate thickness closely matched the flanges and web of the beam. The relocation of the RBS toward the column face led to a slightly higher risk of crack occurrence as the plastic hinge moved further from the column face.