Metal Deck

[bigmig]

Does anyone have suggestions on design references for calculating the allowable concentrated loads for non composite metal decks? I checked out the SDI website and only found a design guide for composite decks.

Thanks in advance

 

[SteelPE]

Not sure if this will help, but when ever I have a question similar to yours I use the following:

http://www.njb-united.com/usd/pages/catalog2008.pdf

 

[jike]

Is this metal deck alone or a metal deck with concrete?

 

[bigmig]

The deck is not covered with concrete.

I guess the concentrated load capacity would depend on the
distribution mechanics of the load (i.e plank, rail, wheel), as well as the load location (on top of rib, or in the valley).

Is the general approach to supply another structural member (flat channel or angle) that can span between supports and
just ignore the deck?

 

[ishvaaag]

Yes. As soon it exceeds the weight of a man, say 100 kgf, it is better to provide specific support. However, heavy decks may deal with heavier point loads so engineering judgement must prevail. On the other hand, if you pinpoint everything causing point loads with spearate substructures, you can employ a deck more adjusted to the distributed loads, this can lead to less cost, especially when a single thickness is preferred for the deck.

 

[JrStructuralEng]

Some suppliers have 'design assumptions' in their tables that might include a nominal point load. I would check there first. If the load is for a RTU I typically never rely on the deck for concentrated loading, unless I calculate the RTU to be of negligible weight or size and not affect the snow loading.

You might frame below the decking to accommodate the weight of the unit and also reinforce the opening in the roof if there is one. Typically this is accomplished with angles or channels between joists/beams.

Or you could frame a 'base' above the roof as you mentioned. Typically, if your metal deck rests on OWSJ's you would design a base to span accross 2 or more joists (Depending on the load, etc). Just make sure the joist supplier knows your intentions!

 

[JAE]

bigmig,

Try this web-page:

http://www.cmc.com/cmcjoist/Data-Sheets.aspx

And click on the two items: "Avoid the Crunch".

 

[bigmig]

Thanks JAE....that is what I was looking for.