Hysteretic Behaviour of Shear Stud Connectors in Composite Steel Moment‐Resisting Frames

In steel moment resisting frames (MRFs) with composite floor slabs, seismic loads are transmitted from the slab into the beam through shear studs. Shear strength degradation of the studs due to cyclic loading results into the loss of the load transfer mechanism and composite action. To date, several low-cyclic, high-amplitude push-out tests have been conducted to characterize the shear stud hysteretic behaviour. These isolated tests showed considerable degradation in the shear stud resistance; nevertheless, they do not simulate the actual hysteretic behaviour of shear studs within a composite steel beam. To elaborate, conventional cyclic push-out tests do not replicate the actual stress state in the concrete slab, nor do they account for the force redistribution between the shear studs. This paper investigates the hysteretic behaviour of shear studs in steel MRFs with composite floor slabs. The load-slip hysteretic behaviour of the shear studs is examined through continuum finite element (CFE) models of 2-bay sub-systems and their corresponding cruciform subassemblies. Moreover, shear force and interlayer slip envelopes are obtained along the composite steel beams. Results of the CFE models are used to propose new design recommendations for shear studs in composite-steel MRFs.