Strength of Slab-Column Connections with Shear and Unbalanced Flexure

Theory is derived for the strength of reinforced concrete interior slab-column connections transferring shear and unbalanced bending moment. The slab at the connection may contain either no shear reinforcement or shear reinforcement in the form of either cranked bars, closed vertical stirrups, or a structural steel shearhead. A beam analogy is used which idealizes the slab as beams running in two directions at right angles into the column faces. The strength of the connection is obtained by summing the flexural, torsional, and shear capacities of the critical beam sections and the contribution from the shear reinforcement. The theory is compared with test results from several investigations and is demonstrated to give a better prediction of the ultimate unbalanced moment strength than the method of ACI 318-71. Yield line theory failure modes for the slab adjacent to the column are also analyzed to determine the upper limit of connection strength.