Fracture of mechanical shear connectors in composite beams

Composite beams in buildings are usually designed using an equilibrium approach that inherently assumes that the mechanical shear connectors have an unlimited slip capacity. Failure of the beam by fracture of the shear connectors through excessive slip is prevented by placing a lower bound to the strength of the shear connectors, that is, the degree of shear connection. A procedure is developed for designing composite beams with any degree of shear connection. It will be shown that fracture of the shear connectors through excessive slip depends not only on the degree of shear connection, the slip capacity of the shear connectors, and the span of the beam, but also on the elastic and plastic cross-sectional properties as well as the ductility requirements of the beam. In this paper, an analysis approach will be developed to illustrate the fundamental parameters that affect fracture of the shear connectors, and design rules will be formulated that can be used in practice.