Behaviour of the longitudinal shear connection in secondary composite beams incorporating trapezoidal steel decking

In order to investigate the complex behaviour and various load-transfer mechanisms that can occur in secondary composite beams incorporating the Australian trapezoidal decks, a number of carefully designed push-out test series were performed. Specific failure modes in conventional specimens were intentionally induced by varying critical parameters including: the width of the concrete flange; the number of welded-stud shear connectors per concrete rib; and the thickness of the steel decking (including its complete omission but maintaining the rib shape). Specimens incorporating concrete-reinforcing and stud performance enhancing devices were subsequently tested to suppress undesirable failure modes. The concrete-reinforcing and stud performance-enhancing devices, which included novel waveform reinforcement and a spiral wire component surrounding individual studs, respectively, when used together prevented premature rib-shearing failure from occurring, and significantly delayed the onset and reduced the effect of rib punch-through failure, hence greatly increased the ultimate strength and ductility of the shear connection. Specifically, the minimum ductility requirement of Eurocode 4: Part 1.1 was satisfied even when using pairs of studs, and it was also possible, when a single stud was placed in the centre of a rib, to achieve a very similar load-slip characteristic to that which would have been obtained in a solid concrete slab.