Types of Steel Joists and Joist Girders
There are three distinct series of joists, the K, LH/DLH and Joist Girders.
K-Series Joists: K-series joists are open web steel joists that are simply supported uniformly loaded trusses that can support a floor or roof deck. These joists have a maximum length of 60 feet. The maximum uniform load for K-series joists is 550 pounds per linear foot (plf).
Each end of "K" series steel joists must be finally attached to the support structure with a minimum of:
- two 1/8-inch fillet welds 1 inch long
- two ½-inch bolts
- or an equivalent connection
LH/DLH-Series Joists: The LH or "Long Span" and DLH or "Deep Long Span" joists are also simply supported uniformly loaded trusses. The LH series may support a floor or roof deck. The DLH series may support only a roof deck.
- The LH series is 18" to 48" in depth, has a maximum span of 96 feet and the maximum uniform loading is up to 1000 plf.
- The DLH series is 52" to 72" in depth, has a maximum span of 144 feet and maximum uniform loading of 700 plf.
Each end of "LH" and "DLH" series steel joists and steel joist girders must be finally attached to the support structure with a minimum of:
- two ¼-inch fillet welds 2 inches long
- two ¾-inch bolts
- or an equivalent connection
- Joist Girders: Joist girders are simply supported, primary load carrying members. Loads are applied through steel joists and evenly spaced along the joist girder top chord. They may span up to 60 feet.
Except for panelized joists, each steel joist must be attached to the support structure, with at least one end on both sides of the seat:
- immediately upon placement in the final erection position
- before additional joists are placed
Panels that have been pre-assembled from steel joists must be attached with bridging to the structure at each corner before the hoisting cables are released.
Knowledge Check Choose the best answer for the question.
3-14. K-Series joists may have a maximum span of _____.
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