Metal Deck on Open Web Timber Trusses

[birneys]

I've got an architect asking me to provided open web trusses (LVL top and bottom chords, steel web members) with an exposed metal roof deck for a single-story preschool building. I'm trying to determine the best method for attaching the metal deck to a timber framing support. Most metal deck manufacturers provide lateral diaphragm capacities for metal deck on joists, but I haven't found any capacities for timber framing. I realize it's not very common, but if anyone has any suggestions or advice, I'd appreciate the assistance. Thanks.

 

[JAE]

In the 4th Edition of the SDI Diaphragm manual they have a section titled "Steel Deck Diaphragms on Cold-Formed Steel Framing".

They say there - [red]"...Because of the thin nature of the support framing, screws are used for fastening, and the limit states checked for the fastener must include the behavior of the fastener in the supporting member." [/red] They then suggest Examples 5A and 5B in AISI D310 for that kind of condition.

Using that as a guide, using wood supporting members it seems that you could still make use of the diaphragm strength principles found in the general SDI deck diaphragm tables but then have to go a step further and check the individual screw in wood capacity.

....architects....

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[birneys]

Thanks for the advice, JAE. I was thinking along those lines as well, but I wasn't sure if values needed to be backed up with testing for different types of deck. It's good to know I was going in the right direction. I got in touch with the deck manufacturer, Epic Metals, and they provided job specific diaphragm values for attaching to timber framing. They didn't seem to be too surprised, so maybe it's more common than I thought. It's not very cost-effective. I ended up with trusses at 3'-6" with a deck that can span around 10'-0"! Apparently, the client isn't worried about budgets . . .

 

[Brad805]

When we looked into this years ago about the only one we found that had any useful data was Simpson Strong Tie. They did some testing with the SDS screw.

 

[birneys]

Brad805, the deck mfr recommended and provided values using a Scots Trugrip screw. I attached the design values for others use.