The behaviour of shear connections in a composite beam with a full-depth precast slab

For the design of shear connections with a full-depth precast slab, it is necessary to investigate strength, stiffness, slip capacity and fatigue endurance. For these purposes, push-out tests were performed with variations of the stud shank diameter and the compressive strength of the mortar. From the experimental work, it could be observed that the deformations of the studs in a full-depth precast slab were greater than those in a cast-in-place slab. The static strengths of the shear connections obtained agree approximately with those evaluated from the tensile strength of the stud shear connectors owing to the effect of the bedding layer. An empirical equation for the initial shear stiffness of a shear connection is also proposed. On the basis of the results of push-out tests, a full-scale composite beam with 8·0 m span was designed and fatigue tests were carried out to study the behaviour of the stud shear connection and its effects on the flexural behaviour of the beam. The bonding and friction between the concrete slab and the steel beam considerably increased the fatigue endurance of the shear connection. Discussions about design are also presented.