Experimental Tests on Concrete Wall–Steel Beam Bolted Web Plate Connections

Abstract The combination of reinforced concrete walls and steel frames is popular for structural systems in high-rise buildings globally, and in New Zealand it has recently emerged as one of the most common configurations for low- and medium-rise construction. Bolted web plate connections in steel gravity load-resisting frames are usually assumed in design to act as a pin, even though they can generate significant moment resistance, and they must accommodate large inelastic rotations during seismic loading. In this study, four full-scale concrete wall–steel beam assemblages using bolted web plate connections were subjected to cyclic loading to quantify their expected seismic response and verify failure modes. Test variables included the presence of a floor slab with reinforcement projecting into the wall, the use of slotted holes, and the type of wall anchorage. After subjecting the connections to a constant gravity shear and cyclic rotation, all four test assemblages exhibited nonductile failure at moderate to high levels of rotation, characterized by concrete breakout. Although there was no loss of gravity load-carrying capacity, concrete breakout was considered a failure of the connection as tested. The rotation capacity of the connection was primarily influenced by bolt slippage, bolt hole elongation due to local yielding, and wall flexural deformation. The inclusion of the floor slab and continuity reinforcement increased the stiffness and strength of the connection and drastically reduced the connection rotation capacity. While adding slotted holes and using bent reinforcing bar anchors instead of headed studs improved the connection rotation capacity, these variations did not alter the ultimate failure mode.