Strength and ductility of shear connection in composite T-beams

![CDATA[Steel framed buildings using composite steel-concrete flooring systems are an economical and widespread form of engineering structure, with increasing use being made of deep, trapezoidal decks as part of the floor slab, which is connected to the steel joist by mechanical headed stud shear connectors. The main economical advantage that accrues to the use of trapezoidal decking is the ability to span large distances, reducing the need for secondary steel beams and for excessive propping. Since the introduction of trapezoidal decking, it has been recognised that a number of potential failure modes need to be considered. Many of these failure modes are observed in conventional push testing of T-beams, and because it is widely recognised that the stress state and load paths present in push tests are not representative of those occurring in flexural beams, the logic that failure modes which occur in conventional push tests are representative of those in full-scale, flexural beams is at the very least questionable, This paper reports firstly on a modified push testing apparatus that has been developed with the express aim of better replicating the loading paths that occur in real flexural beams. It then presents two full-scale tests undertaken On 8 m span beams, with the slabs having trapezoidal sheeting on their soffits with their ribs orthogonal to the steel beams, and which contain only nominal slab reinforcing that would be required for shrinkage and/or fire control. The tests demonstrate that the behaviour is highly ductile, with interface slips in excess of the familiar 6 mm benchmark value being easily achieved. The full-scale beam tests, and their ductile response, are shown to correlate well with the push testing procedure described in the paper.]]