Mechanical Model to Predict the Resistance of the Shear Connection in Composite Beams with Deep Steel Decking

The resistance of a typical shear connection with headed shear studs in a composite beam is analysed in the normal case in accordance with EN 1994-1-1. The reducing effect of a trapezoidal metal decking onto the ultimate load bearing capacity is considered with empirically derived reduction factors and equations, which have been developed in the last century between the late 70th and the early 80th. The RFCS research project “DISCCO” investigated the shear stud resistance with novel types of steel decking. In many cases, the shear resistance, which was predicted by EN 1994-1-1 was not reached in tests. In the respective experiments with composite beams and deep decking, a concrete cone failure mode was identified and not a pure shear failure of the stud. This failure mode acted in combination with the load bearing capacity of the shear stud, which formed one or two plastic hinges in the shaft - depending on the available geometry. Based on these observations, new equations have been developed to predict the shear connection’s resistance with more accurcy. The yield hinge mechanism of the shear stud, which was developed by Lungershausen, was extended by the above mentioned load bearing component ‘concrete cone’. The formulae consider the geometry of the stud and the steel decking, the material strength of the stud and of the concrete material. The statistical evaluation of the developed equations shows a good accordance with test results