Most of the questions we are asked about shear connector studs are sizing questions, and they arrive in the same order every time: what diameters are made, how big is the head, how long can the stud be, and what has to be written on the drawing so the right thing turns up on site. This article answers them one by one.
We manufacture headed shear connector studs to ISO 13918 and to customer drawing at Focal Point, Ludhiana. The figures below are the ones we work to on the shop floor. Where a design code governs your job, that code wins over anything written here.
The standard metric range runs from 10 mm to 25 mm shank diameter. In practice, 19 mm and 22 mm account for most composite bridge and building decks, and 13 mm and 16 mm are used where the slab is thin or the deck profile is shallow.
| Shank diameter | Head diameter | Head thickness | Nearest inch size |
|---|---|---|---|
| 10 | 19 | 7 | — |
| 13 | 25 | 8 | 1/2" (12.7) |
| 16 | 29 | 8 | 5/8" (15.88) |
| 19 | 32 | 10 | 3/4" (19.05) |
| 22 | 35 | 10 | 7/8" (22.23) |
| 25 | 41 | 12 | 1" (25.4) |
Above 25 mm there is no standard entry. We manufacture up to 31.75 mm (1¼") to customer drawing, which is normally a heavy bridge or a crane girder where the designer has run out of stud capacity at 25 mm.
The head is the part that stops the stud pulling out of the concrete, so its size is a design requirement and not a styling choice. As a rule the head diameter is about 1.5 times the shank and the head thickness about 0.4 times the shank, which is exactly what Eurocode 4 asks for when a stud is being relied on to resist uplift.
For a 19 mm stud that means a 32 mm head roughly 10 mm thick. If a drawing calls for a smaller head than that, it is worth querying before the studs are made — the usual cause is a detail copied from an anchor stud rather than a shear connector.
Our heads are hot forged, not machined from bar. A forged head keeps the grain flow continuous from shank into head, which is what you want in a part loaded in bending at the root.
Longer than most people expect. We supply up to 1016 mm (40 inches), although the vast majority of what leaves the works is between 75 mm and 200 mm, because that is what a composite slab needs.
At the short end, the practical limit is set by the code rather than by manufacturing. Eurocode 4 asks for an overall length after welding of at least four times the diameter for a stud acting as a shear connector, so a 19 mm stud should not be shorter than about 76 mm. Long studs are a different problem: they are used for deep haunches, encased beams and stud rails, and the question there is whether the stud gun can deliver the energy to weld it. Tell us the length and we will tell you what it needs.
The length you order is the length before welding. Arc stud welding burns off part of the shank — about 5 mm on a 19 mm stud. A stud ordered at 100 mm stands roughly 95 mm above the flange once welded. If the drawing gives a finished height, say so on the enquiry and we will add the burn-off.
Low carbon steel, and deliberately so. Carbon is held to about 0.20% maximum because the stud has to weld to the beam flange in under a second without cracking; a higher carbon steel would harden in the weld zone. The usual property requirements are a tensile strength of at least 450 N/mm², a yield of at least 350 N/mm² and elongation of at least 15%.
That is why a shear stud is not a high tensile part and should never be substituted with an 8.8 or 10.9 fastener that happens to be the same diameter. The design capacity of a shear connector comes from the concrete around it as much as from the steel in it.
Each stud is supplied with an aluminium ball flux tip on the weld end. The tip is a deoxidiser, it is consumed in the weld, and a stud without one will not weld properly.
Six things. Get these on the drawing or in the BOQ line and there is nothing left to guess:
A complete line reads something like: 19 mm dia × 150 mm long headed shear connector stud to ISO 13918, plain finish, with matched ceramic ferrule, 12,000 nos, EN 10204 3.1 certificate.
Send the beam size, the deck profile and the slab thickness and we will write the stud line for you. No obligation, and no sales call unless you ask for one.
Through-deck welding is the common case in buildings: the stud is welded through the profiled steel sheet into the beam flange below. Two things then drive the size.
The stud has to stand clear of the deck rib. Most codes want the head at least 30 mm above the top of the rib, and the stud height after welding to be at least twice the deck depth. A 19 mm × 100 mm stud on a 50 mm deck is the workhorse combination for that reason.
The sheet also has to be thin enough and clean enough to weld through. Galvanised deck sheet up to about 1.25 mm total welds reliably; beyond that, or with two overlapping sheets at a joint, the sheet should be pre-holed. Rust, paint or water at the weld point will cause a failure regardless of the stud.
Spacing is a code matter, but the limits that decide a layout are worth knowing before the drawing is issued. Eurocode 4 sets a minimum spacing of five diameters in the direction of the shear force and two and a half diameters across it in a solid slab, with a wider limit in other cases. For 19 mm studs that is 95 mm along the beam.
There is also a minimum distance to the flange edge, and the flange has to be thick enough that the weld does not pull the plate. Where a layout will not fit, the answer is usually a larger diameter in fewer positions rather than crowding small studs together.
Yes, for drawn arc welding. The ferrule contains the molten pool, shapes the weld collar and shields the arc. It is broken off and discarded after welding, so one is consumed per stud.
Ferrules are matched to stud diameter and to stud type. Headed shear connectors and plain unthreaded studs take one ferrule form, threaded studs another, and reduced-shaft threaded studs a third — they are not interchangeable. If you are ordering studs and ferrules separately from two suppliers, confirm the ferrule type against the stud type, not just the diameter. We cover the types in detail in threaded studs vs headed shear studs.
By bending it. The standard site check is to strike the stud sideways with a hammer and bend it about 30 degrees off the vertical. A sound weld holds; a bad weld snaps at the collar. Studs bent in the test and found sound are normally left bent rather than straightened back.
The visual check comes first: a complete weld shows an even collar of flash all the way round the base. A collar missing on one side means the arc was off centre, usually from a bent leg on the gun or a ferrule that was not seated flat.
It matters for the ferrule and for the stud gun chuck, not for the concrete. Indian and European jobs are specified in metric to ISO 13918; American and Middle Eastern jobs often arrive in inches to AWS D1.1. The sizes sit close together — 19 mm and 3/4" are 0.05 mm apart — but they are not the same part, and a ferrule for one will not seat correctly on the other. We make both, so state the system on the enquiry.
Yes, and a good share of our stud work is exactly that. Intermediate lengths, diameters above the standard table, longer heads, reduced heads to clear a reinforcement layer, and studs to a project drawing with a customer mark on the head are all routine. Our range is 13 mm to 31.75 mm diameter, in lengths to 1016 mm.
What we need from you is a dimensioned sketch and the quantity. If the design is fixed only in your head so far, send the beam and slab detail instead and we will propose the stud.
If something about stud sizing is still unclear after reading this, ask us — the answer will be added to this article so the next engineer finds it here. Questions are answered by the works, not by a call centre.
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More on this product: shear connector studs · shear studs vs PSR studs · data sheet (PDF)
S.R. Forgings manufactures headed shear connector studs, threaded weld studs and PSR punching shear studs at E-615, Phase VII, Focal Point, Ludhiana 141010, India. Dimensions given here are nominal and for guidance; where a project code or drawing governs, it takes precedence.