What Is a Shear Stud?
A shear stud is a headed steel stud welded to the top flange of a steel beam so the beam and the concrete slab act as one composite unit — the studs transfer horizontal shear between them. Composite action lets the slab contribute to the beam's strength, cutting steel weight 20-30% versus non-composite design. If you have ever seen the rows of short pegs on a steel beam before the deck pour, those are shear studs.
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How composite action works
Without studs, the slab slides on the beam and each bends independently. With studs, they bend together — the slab becomes the compression flange of a much deeper effective section. The engineer calculates the required number of studs from the shear flow between slab and beam, places them per AISC rules (spacing limits, edge distances, minimum per rib of deck), and the composite capacity sets the beam size.
Installation and inspection
Studs are welded with a stud gun through the metal deck in a fraction of a second per stud — thousands per floor. Quality control includes bend tests (bend a sample stud 30 degrees; the weld must hold) and visual inspection of the weld flash. Special inspection per IBC covers stud welding on most commercial projects. Missing or failed studs in a zone mean that beam is not composite there — the inspector's report goes to the engineer for evaluation.
Design notes
Stud capacity depends on concrete strength, deck profile (studs through deep deck ribs get reduction factors), and placement. The engineer also checks the slab for the concentrated stud forces and details the deck attachment. In seismic moment frames, composite action at the beam ends is deliberately limited or the slab is isolated — full composite action changes the frame's intended hinge behavior, and the connection design accounts for it.
The bottom line
Shear studs make slab and beam act compositely, saving 20-30% of steel weight. Weld quality is special-inspected; in seismic frames, composite action at beam ends is deliberately controlled.
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