Drop-In Top Flange Shear Connection Full-Scale Testing

The United States (US) structural steel industry is making a concerted effort to increase the speed of steel building projects. This study introduces a novel shear connection, named drop-in top flange connection, designed to enhance the erection speed and safety of steel-framed structures. The drop-in connection consists of a pair of shop-welded angles to a column (or plate) and subsequently field-bolted to the top flange of a girder or beam that is coped on the bottom flange. This design allows a stable and efficient installation without temporary support until the bolts are secured. Eleven drop-in connections and one industry-standard single-plate shear connection were fabricated and tested at full-scale under monotonic load. The impact of different geometric parameters, such as angle size, bearing length, angle orientation, angle spacing, and weld geometry, on the connection strength, rotational ductility, rotational stiffness, and failure mode was examined. The proof-of-concept test results showed that the drop-in connections developed sufficient strength well above the shear demand. Additionally, the tested connections demonstrated sufficient rotational ductility and low moment resistance to be qualified as simple connections. The limit states achieved by the drop-in connections included flange yielding, angle yielding and buckling, fracture of weld group, and column web yielding for beam-to-column connections. The drop-in connections provided sufficient lateral and out-of-plane rotation resistance for the supported girder to be laterally stable, within the limitations of the test setup. Overall, the experimental performance of the drop-in top flange connection showed tremendous promise for future applications in steel frame buildings.