Effect of composite slab and connection detail on cyclic behavior of steel beam-to-HSS column moment connections

Abstract

This paper investigates the effects of composite slabs and connection details on the cyclic performance of steel beam-to-HSS column moment connections through advanced numerical models. Sophisticated 3D finite element (FE) models and simplified 2D plastic hinge models are developed for six connections and validated against experimental data from cyclic loading tests on five large-scale specimens. The analysis focuses on how composite slabs and connection details affect various cyclic properties, including hysteretic behavior, strength/stiffness degradation, cumulative plastic deformation, energy dissipation, equivalent fatigue fracture life, strain distribution, and failure modes. The findings indicate that composite slabs enhance the stability of the beam top flange but limit the cumulative plastic deformation ratio (η) and energy dissipation (∑E), with composite beams exhibiting only 50%–67% of η and 35%–66% of ∑E compared to bare steel beams. Furthermore, no-weld access hole (WAH) connections, in contrast to field-welded connections, effectively shift the plastic hinge outward, thus delaying flange fracture. The average η of no-WAH connections was 1.6 and 2.6 times higher than that of modern field-welded and pre-Kobe connections, respectively, and the average ∑E was 2.0 and 3.8 times higher. The proposed FE models offer comprehensive seismic assessments for beam-to-HSS column connections, aiding in detailed parametric analysis. The simplified plastic hinge models, which incorporate cyclic deterioration and fracture behavior, provide a more efficient and practical modeling approach and parameters for system-level frame analyses.