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CONSTRUCTION KNOWLEDGE  >> METAL >>

STEEL JOISTS & DECKS
 

1. What Should I Know about Steel Joists and Deck?
2. What Public Domain Documents are Available for Further Study?
3. Tricks of the Trade & Rules of Thumb for Steel Joist and Deck:

What Should I Know about Steel Joists and Deck?

A steel joist and deck structural system for floors above grade often is the most economical floor system, particularly for areas with a low  likelihood of earthquakes. Steel joists use the truss structural principle, which results in a very high load capacity to member weight ratio. A common floor design is steel joists at 2' on center, with a 28 gauge form deck spanning perpendicular to the joists and 3" or 4" of concrete floor placed on the form deck.

The website below provides excellent, free downloadable catalogs for steel joists and deck:
http://ww1.newmill.com/services/download_catalog.html

One of the challenges to installing this type of floor system regards the flatness of the floor. Frankly, it's difficult to get a flat floor. Since the joist and deck floor system is so efficient, there tends to be a good bit of deflection in the joists when under load. A few big construction workers, gathered in one spot while placing the concrete deck, can create some noticeable joist deflections. Then the concrete tends to get placed thicker in that area, since the deck is lower. When the workers move, the deck may come up or it may be permanently deflected due to the extra concrete weight. It's not impossible to get a flat floor, but it is a challenge.

Welding of the steel deck should also be carefully monitored. The specification should detail how often the deck should be welded to the steel joists and how often side lap welds are required. Sometimes these welds get made haphazardly and don't create the necessary bonds.

Whenever you work on raised floor systems, be careful about fall protection. Many workers die each year from falls. Learn to look critically at the safeguards that are in place. Make sure the temporary railings really are erected correctly and that they stay in place. It's a truth on the construction site that temporary railings get in the way and get taken down. The Construction Supervisor should plan for that fact and make sure that a floor stays protected from fall hazards. The alternative can be quite ugly.

What Public Domain Documents are Available for Further Study:

The US Navy produced a chapter about structural steel and steel joists in their Steelworker Volume 2 training manual that has some good information. Titled Steelworker Volume 2 Training Manual, the official name is NAVEDTRA 14251, November 1996.
 

Tricks of the Trade & Rules of Thumb for Steel Joists & Deck:

1. Be aware of floor deflections when placing concrete on steel joists and deck.
2. Check welding quality and quantity of steel decks to steel joists.
3. Make sure temporary railings get erected correctly and stay in place for fall protection.