Monotonic behaviour of composite column to beam connections

An experimental investigation into the behaviour of composite column-to-beam connections using ten large-scale connections has been conducted, four under monotonic loading and six under cyclic loading. This paper presents the details and results of the four preliminary monotonic tests. Details and results of the cyclic tests are reported in a companion paper. All connections consisted of a circular concrete-filled steel tubular column, a compact universal beam section and a shop fabricated connection stub. It is a direct connection of the beam to the tube wall (using flange connection plates, and web cleat plates) and four straight reinforcing bars welded to the top and bottom flanges and embedded into the concrete core. It was found that the connection strength increased as the capacity of the embedded bars increased, to a stage where no connection failure occurred, and the beam formed a plastic hinge outside the zone of influence of the bars. The bars were very effective in transferring both compressive and tensile loads directly into the column, and connection behaviour in terms of strength and stiffness was adequate to classify it as a rigid connection.