Product Introduction
Headed shear connector studs, commonly referred to as Nelson studs, manufactured to ISO 13918 and AWS D1.1/D1.1M for drawn‑arc stud welding in composite steel‑concrete frames. They are available for both through‑deck welding onto the beam flange after the metal deck is positioned, and for direct‑to‑steel welding where the concrete slab bears directly on the steel section. The studs create a reliable mechanical shear connection that ties the cast‑in‑place concrete slab to the structural steel and resists the longitudinal shear forces developed under load.

Material & Mechanical Properties
Produced from weldable low‑carbon steel with a controlled chemistry that stabilises the drawn arc and promotes full‑penetration fusion. The welded joint achieves the tensile and bend‑test values required by AWS D1.1 and ISO 14555. The connection develops a shear capacity greater than the shank cross‑section, ensuring that any overload manifests as a ductile failure remote from the weld.

Dimensions & Identification

• Nominal diameters: 10 mm – 25 mm (metric) and equivalent imperial sizes

• Length before welding: 40 mm – 300 mm

• Head form: cheese head (cylindrical) per ISO 13918

• Identification: each stud head carries the manufacturer’s identification mark, providing full traceability to the production batch

Ceramic Ferrules
A cordierite ceramic ferrule is supplied with every stud. The ferrule surrounds the weld zone during arcing, shielding the molten pool from atmospheric contamination and controlling fillet shape. Cordierite’s thermal shock resistance allows it to endure the rapid temperature rise of stud welding without melting or fracturing. Ferrules are removed once the weld has solidified.

Installation & Weld Verification
Installation uses drawn‑arc stud welding equipment, not resistance spot welders. The stud gun lifts the fastener, initiates an electric arc that melts the stud tip and a local portion of the beam flange, then plunges the stud into the molten pool — penetrating the metal deck without pre‑drilled holes when welding through‑deck.
Post‑weld quality assurance includes a visual examination of the 360° flash and fillet geometry, followed by a mechanical bend test. A mallet blow to the side of the welded stud bends it to the required angle. A correctly welded stud remains attached and deforms without fracture at the weld interface; a stud that snaps off at the beam under this bending‑shear force indicates an unsound weld and must be replaced.

Application Suitability
Composite floor and roof decks in multistorey steel‑framed buildings, bridge decks, industrial platforms, and any project where the structural engineer specifies shear connectors to achieve full composite action between the concrete slab and the steel frame. The stud diameter, installed height, and quantity per beam are determined by the structural design; installation is carried out by specialist stud‑welding subcontractors.

Technical Parameters