How to Camber a Steel Joist
When a steel joist is manufactured, it is designed slightly curved, convex upward. Even on a flat-roof system, the joist is curved with a slight upward radius to compensate for how the joist deflects when the weight of the building and roof systems are applied. The camber is built into the joist when it's manufacturer. The amount of camber is based on the length of the joist, and the amount of weight the joist will support.
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Things You'll Need
- Building blue prints
- Joist dimensions
- Steel Joist Institute (SJI) engineering tables
- Steel manufacturing equipment
- Steel rebar
- Welding equipment
Instructions
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1
Measure the distance the steel joist will span from wall to wall in the building. This is called the joist's span.
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Identify from the SJI tables the amount of camber, measured in inches, required for the specific joist and span.
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3
Bend the upper and lower steel cords during the manufacturing process so that they have the appropriate camber. The camber is measured by drawing a straight line between the ends of the joist, and measuring upward at the center of the arch.
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4
Weld the rebar/steel bar webbing into the joist, creating a joist which permanently curves upward. When the joist is installed in the building, and floor or roof systems built on top of the joists, the structure's weight will cause the joist to deflect and flatten out. Without the chamber, the joist would deflect, and cause the floor or roof system to sag, increasing the likelihood of structural failure. The chamber creates a stronger joist.
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References
Resources
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