NASCLA Accredited Commercial General ContractorMetalsMedium
A steel fabricator is designing a connection for a light gauge steel truss. The connection requires multiple fasteners to transfer shear forces between two members. Given the thinness of light gauge steel, what is the primary concern when selecting and installing fasteners for such connections?
- AMinimizing the aesthetic impact of the fastener heads on exposed surfaces.
- BEnsuring the fasteners are resistant to high-temperature welding failures.
- CPreventing pull-out or tear-out of the fastener from the thin steel sheet.
- DAchieving sufficient tension in the fasteners to create a slip-critical connection.
Show answer & explanationAnswer & explanation
Correct answer: C. Preventing pull-out or tear-out of the fastener from the thin steel sheet.
With light gauge steel, the thinness of the material makes it susceptible to the fastener pulling out or the material tearing around the fastener hole before the fastener itself fails. Therefore, selecting fasteners that optimize pull-out and tear-out resistance is a primary concern.
Why the other options are wrong
- A. Aesthetics are a design consideration, but structural integrity and strength (preventing pull-out/tear-out) are the primary engineering concerns.
- B. Fasteners are typically mechanical in light gauge steel, so welding failure isn't the primary concern, though some connections can be welded.
- D. While tension can be a factor, the primary concern for shear connections in thin material is the material's ability to hold the fastener.
Fastener Pull-out/Tear-out (Light Gauge Steel)
Failure modes in light gauge steel connections where the fastener either pulls completely out of the sheet or the sheet material around the fastener hole tears, due to insufficient material thickness or strength.
- Directly related to the thinness of the light gauge steel.
- Requires careful selection of fastener type, diameter, and edge distances.
- Can be mitigated by using larger diameter fasteners, washers, or specific screw thread designs.
Memory trick: Light Gauge: Thin Sheet, Tight Fit, No Tear.