How Tube Framing Clamps Ensure Concentric Loading of Steel Joists

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A Steel Joist Is A Beautiful Thing. Why Not Treat It Right?

“The design of open web steel joists is based on concentric loading. Asymmetrical loading can reduce joist strength.”
– Steel Joist Institute
Treating a steel joist right requires loading joists in accordance with their design criteria.
Loads must be applied to both chord angles without creating a torsional moment. With that fact in mind, Chicago Clamp Company has designed and tested their Tube Framing Clamp System.

Chicago Clamp design showing concentric loading mechanism for steel joists, highlighting load application through the top chord and symmetrical load distribution during uplift.

  • The clamp’s strength and stiffness transfer the load vertically to the center of the joist’s top chord in download and transfer symmetrically during uplift.
  • Testing was performed using rocker end-attachments to avoid reliance on torsional strength of the joist chord.
  • Clamping to joists avoids possible detrimental effects of welding to joists that are under stress due to loading.
  • Clamping has the economic benefits of reducing labor costs, reducing installation mistakes, and reducing job delays (associated with locating and sizing curbs and openings prior to steel joist installation).
Rocker end-attachment for Tube Framing Clamp System demonstrating load application without torsional moments, showcasing clamping mechanism and structural integrity for steel joist installations.
Fall protection test using rockers
Hydraulic ram testing setup for Tube Framing Clamp System, featuring clamped steel joists and electronic data acquisition equipment, demonstrating load application without torsional moment.
Test with hydraulic ram
Two engineers conducting a fall protection test on a Tube Framing Clamp System using hydraulic ram in a testing facility, with steel structures in the background.
Electronic data acquisition