Modified Connection Details for Single Plate Steel Connections under Fire

Single plate (shear tab) connections connect a beam to a girder or to a column, and they are designed to resist only shear loads. In a fire event, the axial restraint provided by adjacent structure creates unanticipated compressive and tensile forces in the beam and thus the connection. Using finite element (FE) models with contact elements, this study examines shear tab connections under fire. The model, validated by experimental data, represents the connection as well as a portion of the surrounding structure in a composite floor framing system. By extending the model beyond the connection region, the combination of shear, axial force and moment are properly represented in the connection during the fire. Previous studies have shown that large beam rotations and tensile forces result in bolt tear out (beam bearing) or bolt shear failure. This study shows how some simple modifications in the connection model affects the response (if at all).