Roof Deck Capacity

[oengineer]

I am working on a DIAPHRAGM DESIGN for my roof deck for a school I am designing. I am trying to determine the capacity of the roof deck. I am using a 3.5" acoustical deck. I am new to DIAPHRAGM DESIGN for roof deck so suggestions/ comments are helpful.

 

[jayrod12]

Most of the deck suppliers, Canam for example, have published capacities for different fastenings and deck types etc. Start there.

 

[Ganesh Persaud]

You can use this as an example.

https://www.newmill.com/pdfs/diaphragm-design.pdf

 

[skeletron]

Most designs start off with assuming the girder model — the diaphragm acts as a web while the chord elements at the edges provide tensile/compressive resistance caused by flexure. Also be aware of how your diaphragm is classified (rigid, semi-rigid, flexible). If you're dealing with a metal deck, the diaphragm is likely flexible. The analysis is straightforward. As @jayrod12 mentioned, most deck suppliers have published capacities for fasteners, decking, and requirements. I learned through the Vicwest manual, which is no longer published. But here is the Canam manual (example on Page 22):

https://www.canam-construction.com/wp-content/uploads/2014/12/canam-steel-deck-diaphragm-canada.pdf

And here is the 1995 version of the SDI Diaphram Manual:

https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=1012&context=ccfss-sdi

Also be aware if there are seismic provisions in your area.

 

[JLNJ]

Are you using EPIC deck? If so, there is a whole manual for the diaphragm design of the various EPIC deck profiles. EPIC makes some nice products.

If you don't understand the concept of diaphragm design, then you would be best served finding a more senior engineer to help you during the process.

 

[KootK]

1) As the title would imply, the attached article is a decent place to start.

2) Here's another oldie but goody: Link

3) I'd recommend that your next stop be the Diaphragm Design Manual by the Steel Deck Institute. It contains numerous examples and practical tips. It's a bit expensive but I'd consider it a worthwhile investment for any firm doing steel building design. You can extract much of the utility of the document from older, freely available versions: DDM V3.0

4) Do feel free to work out some preliminary concepts and return here with some sketches for us to review. I would be happy to help you work through your deck design problem as, no doubt, many other forum members would. I'll monitor the thread for updates.