4.5. Composite Design

4.5.1. What is the minimum concrete cover required above the head of a shear stud connector?

At one time, such a requirement did exist in the AISC Specification. However, the strength of a shear stud connector depends upon the strength of the connector itself and the cone of concrete under the head, not the concrete over it. Accordingly, the cover requirement was eliminated. The reader is cautioned, however, to allow sufficient slab thickness to accommodate possible variations in composite beam shape, such as that due to camber, which could otherwise cause shear stud connectors to protrude through the top of the slab.

4.5.2. Can a shear stud connector be welded to the beam flange at any location across its width as long as there is adequate space for the weld?

Yes, however, from the 2005 AISC Specification Section I3.2d(6), "The diameter of studs shall not be greater than 2.5 times the thickness of the flange to which they are welded, unless located over the web."

Goble, G.G., 1968, “Shear Strength of Thin Flange Composite Specimens,” Engineering Journal, Vol. 5, No. 2, (2nd Qtr.), pp. 62-65, AISC, Chicago, IL.

4.5.3. What is meant when a shear stud is said to be located in the strong or weak position?

Modern steel deck profiles generally have a reinforcing rib at the center of the corrugation that prevents the welding of shear stud connectors directly in the center of the rib. When a stud is welded on the side of the rib that is away from the point of maximum moment, it is said to be in the strong position (see Figure 4.5.3-1) because more load can be transmitted to it. Conversely, a stud that is welded on the side of the rib that is toward the point of maximum moment is said to be in the weak position. For further information, refer to Easterling et al. (1993).