Tests on Slab-Column Connections with Shear and Unbalanced Flexure

Tests were conducted on eight 1/2-scale models of reinforced concrete interior flat plate-column connections transferring shear and unbalanced moment from gravity and simulated seismic loading. The slab at the connection contained either no shear reinforcement or shear reinforcement in the form of either cranked bars, structural steel shearhead or closed vertical stirrups. The simulated seismic loading was statically applied, either monotonically or cyclically in the inelastic range. The strength and ductility of the connections, and the modes of failure, were compared. The connections without shear reinforcement failed suddenly in diagonal tension. The use of cranked bars as shear reinforcement increased the strength of the connection but did not increase the ductility. The use of a structural steel shearhead resulted in an increase in strength and in a limited increase in ductility. The use of closed vertical stirrups around the slab bars, which passed through the column, resulted in an increase in the strength and in a substantial increase in the ductility of the connection.