Shear-slip behaviour and ductility of composite dowel connectors with pry-out failure

The flexural strength of steel and concrete composite beams is influenced by both the connectors' shear capacity and the slip across the steel-concrete interface. However, plastic design strategies commonly used in engineering practice assume a rigid-plastic connector behaviour neglecting the real nonlinear shear-slip characteristic. As to prevent a premature connector failure due to excessive beam end slip, design codes usually allow only ductile shear connectors with a deformation capacity δult of at least 6 mm to be used. But, especially for innovative shear connectors like composite dowels, approaches for assessing and describing the nonlinear shear-slip behaviour and deformation capacity are lacking, so far. Therefore, the present paper proposes models for the calculation of the slip capacity and the description of the shear-slip characteristic, considering the composite dowels' shear capacity and elastic connector stiffness. The proposed models can be used to replace expensive and time-consuming shear tests for the characterization of the composite dowels' deformation capacity. Furthermore, they allow to define the required material combinations and to carve out the dowels' geometrical dimensions for a ductile connector behaviour.