Drift Capacity of Slab-Column Connections Reinforced with Headed Shear Studs and Subjected to Combined Gravity Load and Biaxial Lateral Displacements

Final report on research conducted as part of NEES-2010-0983 Project Assessment of Punching Shear Vulnerability of Slab-Column Connections with Shear Stud Reinforcement. Results from an experimental investigation of the behavior of slab-column connections reinforced with headed stud reinforcement under simulated earthquake loading are presented. Four non-prestressed concrete slab-column connection subassemblies were tested under simulated gravity (gravity shear ratio of ½) and biaxial lateral displacement reversals. The slabs, which were nominally identical aside from the shear stud reinforcement design, had a flexural reinforcement ratio in the column strip, based on the effective depth, of 0.7%. Shear stud reinforcement in the test specimens varied in terms of amount and spacing, both between and within stud peripheral lines. Although the lateral strength of the specimens was governed by the flexural capacity of the slab, severe concrete degradation ultimately limited the drift capacity of the connections. Signs of punching related damage were first observed during the cycle to 1.85% drift in each loading direction. Test results suggest that the minimum amount of shear reinforcement required in Section 21.13.6 of the 2011 ACI Building Code when neither a drift nor a combined shear stress check is performed ( Final report on research conducted as part of NEES-2010-0983 Project Assessment of Punching Shear Vulnerability of Slab-Column Connections with Shear Stud Reinforcement. Results from an experimental investigation of the behavior of slab-column connections reinforced with headed stud reinforcement under simulated earthquake loading are presented. Four non-prestressed concrete slab-column connection subassemblies were tested under simulated gravity (gravity shear ratio of ½) and biaxial lateral displacement reversals. The slabs, which were nominally identical aside from the shear stud reinforcement design, had a flexural reinforcement ratio in the column strip, based on the effective depth, of 0.7%. Shear stud reinforcement in the test specimens varied in terms of amount and spacing, both between and within stud peripheral lines. Although the lateral strength of the specimens was governed by the flexural capacity of the slab, severe concrete degradation ultimately limited the drift capacity of the connections. Signs of punching related damage were first observed during the cycle to 1.85% drift in each loading direction. Test results suggest that the minimum amount of shear reinforcement required in Section 21.13.6 of the 2011 ACI Building Code when neither a drift nor a combined shear stress check is performed (v_s >3.5√(f _c^'), psi or 0.29√(f _c^') MPa), is adequate for connections subjected to a gravity shear ratio of up to 50% and resultant drifts from biaxial displacements of up to 2.0% if studs are spaced at less than 2d within the first two peripheral lines. For larger drift demands, a maximum stud spacing within the first three peripheral lines of 1.5d is recommended.