Shear connectors in the form of shear studs are typically welded to the top flange of a steel section through the metal deck, providing a shear connection between the steel section and concrete to achieve composite action between the concrete slab and steel beam. Stud welding the shear stud, metal deck, and steel section together creates a single, efficient operation.
In this article, we’ll discuss the following:
- What is stud welding
- What is the shear stud welding process
- How strong is stud welding
- Where to use the stud welding
- Important facts about stud welding
- Composite floor design and stud welding
- Advantages of stud welding in composite floor construction
What is Stud Welding
Stud welding, also known as drawn arc stud welding and arc welding, is the action of welding a shear stud to a metal object, for example, a metal deck.
The terms “stud welding” and “shear stud” are commonly used in the process of attaching steel frames to composite floor constructions.
What is the Shear Stud Welding Process
To fix steel beams to concrete, shear studs are commonly installed using a stud welding gun which employs a potent electric current to heat the tip of the stud and create a positive electric arc.
The welding gun holds the studs above the parent material at a set height and initiates a pilot-arc upon triggering. This triggers a main arc that generates heat exceeding 1400 degrees, causing the stud’s welding end to liquefy and create welding splatter. The molten pool that forms on the plate then fuses the shear stud to the parent material when it’s forcefully driven into it. Depending on the connector’s size, the process can last anywhere from 0.06 seconds, and the stud’s length reduces by roughly 5mm on average.
How Strong is Stud Welding
Although the process is fast, the welded connection surpasses the strength of either the stud or the parent material and can endure more substantial static loads. Stud welding can also be used on parent materials as thin as 1.2mm.
Where to Use Stud Welding
The construction industry, particularly in steel frame construction, frequently employs stud welding techniques to attach shear studs to the top flange of steel beams. Although some stud connections are pre-welded to steel beams, it’s more typical to weld them through steel decking sheets, known as “thru deck welding.” Following this, a concrete slab reinforced with steel mesh sheets or steel fibers is poured onto the steel decking, covering the exposed top of the studs.
To prevent the accumulation of contaminants like moisture or dirt that could impair the weld quality, thru deck stud welding should be done shortly after laying the steel decking. These shear connectors produce a robust vertical link between the steel beam, steel decking, and reinforced concrete floor slab, enhancing the overall composite action and transferring load-bearing force between the materials. The shank resists horizontal shear, while the head prevents vertical uplift.
In summary, the composite floor slab resulting from this process is light in weight yet has the capacity to bear more significant static and dynamic loads than any of the individual materials alone.
Important Facts about Stud Welding
Since the stud welding process involves high temperatures that can be a fire hazard, only a trained professional should carry out the process, taking into account health and safety best practices to evaluate conditions.
The metal splatter resulting from the arc generated between the tip and parent material during the stud welding process will scatter in all directions above and below the welding location.
If the dispersed molten metal comes into contact with other surfaces or materials undetected, it can continue to smolder and pose a significant risk of fire outbreaks both during and outside of working hours on the construction site.
Standard fire prevention techniques are inadequate due to the characteristics of the molten splatter. Although fire protective monoflex could potentially reduce the risk by limiting the distance the splatter is dispersed, it is not entirely foolproof as a preventive measure.
Composite Floor Design and Stud Welding
When developing composite floors in a steel frame structure, structural engineers consult load/span tables produced by your metal deck manufacturer. These tables enable the engineer to evaluate the concrete floor slab’s thickness and mesh reinforcement needed to attain a specific fire rating or construction standard.
After designing the reinforced concrete floor slab, the structural engineer can then complete the design of the composite beam, which involves the steel beam and the composite floor slab.
Advantages of Stud Welding in Composite Floor Construction
Using stud welding, a metal shear stud can be quickly and effectively bonded to a parent material, resulting in a welded joint that is stronger than either the stud or the parent material.
The shear stud can be welded from just one side, allowing the process to be carried out on-site after the beams have been installed, thus reducing the need for excessive component handling. Additionally, stud welding equipment is portable and does not hinder the welder’s mobility.
The opposite side of the steel beam remains unaffected by the process, and typically, the area surrounding the shear connector is flat and free of debris.
Stud weld joints are impervious to leaks since no holes are drilled in the steel beam. This also minimizes the potential for corrosion and prevents any detrimental effects on the strength of the steel beam.
Composite Metal Decking from CSM Metal Deck
At CSM Products & Solutions, we know metal deck and are an SDI-certified member. We manufacture metal deck to your specifications in a variety of depths, widths, and gauges with competitive pricing and timely delivery. We also have stock inventory ready to ship, including metal roof deck, composite deck, and form deck.
At CSM, our manufacturing team has the knowledge and tools to create a metal deck that meets your construction project’s needs. Please contact us today if you need guidance or recommendations on which metal deck is best for your particular construction application.
