Strength of headed stud shear connection in composite beams

The shear connection forms the crucial part of any composite member subjected to flexural loading. This is clearly evident in partial shear connection where the strength and ductility of the shear connection directly defines the capacity of the whole beam. In recent years trapezoidal steel decking with wide open ribs have been introduced into the Australian market. These decks offer significantly different behaviour to the closed rib decks considered in Composite Structures Standard AS2327.1 (Standards Australia 2003). It is widely acknowledged that steel decking with wide open ribs can significantly reduce the strength and ductility of the shear connection in composite beams. The approach primarily used around the world to take into account the weakening effect of this type of decking is to apply a reduction factor to the nominal strength of the same connector in a solid slab. Consequently it is critical that the strength and behaviour of the connector in the solid slab is known and understood. This paper summarizes the results of an extensive review of various push-out test series in order to determine the mean strength of headed stud shear connectors in solid slabs. It also investigates the influence that different test set-ups can have on the connector strength. Based on the findings, an analysis of previous test series of stud shear connection incorporating trapezoidal steel decking is undertaken which indicates the unreliable and unconservative nature of the reduction factor approach