Diaphragm Options

[32romeo]

I have a simple rectangular building with roof system consisting of deep long span trusses. The building was originally designed with 1.5" steel deck as the roof diaphragm. The owner wants to delete the deck and go with a standing seam roof on purlins, so I'm trying to come up with other options for tranferring the diaphragm load. Several options include diagonal cable bracing or straps. Any other ideas?

 

[whyun]

In the past, I attached the lighter gage standing seam deck on top of 1.5" B deck diaphragm.

 

[azcats]

I haven't done much work with standing seam roofing. However, what I have seen is so light that it would have trouble spanning between purlins. I've always had to use a metal or plywood deck below the roofing for structural support.

 

[geoffdale]

We have used plenty of standing seam roofing in the apst, mostly on pre-engineered rigid frame buildings. We always use moment frames or x-bracing, and the purlins are normally at 2'-0" or so spacing maximum.

 

[UcfSE]

The standing seam may not be able to provide the bracing required for your truss top chords. That is something to watch for in the truss design. Also, with the standing seam on top of purlins, you may have a hard time transferring the lateral shear to and from the standing seam. The idea of having the 1.5" deck with standing seam over it is a good one IMO. Then the standing seam is not structural.