Z Purlins - Revisited
Z Purlins - Revisited
(OP)
I have an existing PEMB, built by American Buildings. At least I think it was. Old logo on the building says American, and the roof Z purlins are 9.5" deep. The only PEMB company that makes 9.5" deep Z purlins is American Buildings, as far as I know.
Anyway, my client wants to add parapets. This creates new snow drift loads. For an old roof with no parapets, obviously my existing 9.5" Z purlins will not work. The standing seam roof also does not work. I need the Z properties to figure out the best solution.
When I was on the scissor lift investigating the building, I measured the purlins depth and width, but that was it, figuring it would be a common shape, and I could easily find the section properties. Well, was I wrong. I have tried contacting American Buildings several times with no luck.
Does anyone out there have section properties for American Buildings 9.5" Z purlins?
And yes, I already have the CFS program by rgsoftware. Would work great, but I only have the height and width of the existing Z purlins, and I don't want to rent another scissor lift to get the other properties!
Thanks
Anyway, my client wants to add parapets. This creates new snow drift loads. For an old roof with no parapets, obviously my existing 9.5" Z purlins will not work. The standing seam roof also does not work. I need the Z properties to figure out the best solution.
When I was on the scissor lift investigating the building, I measured the purlins depth and width, but that was it, figuring it would be a common shape, and I could easily find the section properties. Well, was I wrong. I have tried contacting American Buildings several times with no luck.
Does anyone out there have section properties for American Buildings 9.5" Z purlins?
And yes, I already have the CFS program by rgsoftware. Would work great, but I only have the height and width of the existing Z purlins, and I don't want to rent another scissor lift to get the other properties!
Thanks






RE: Z Purlins - Revisited
Dik
RE: Z Purlins - Revisited
At some point, you have to think it'd be more cost effective to demolish the existing building and build new.
RE: Z Purlins - Revisited
And the funny thing is, the original designer won't be any help, unless the building falls down and than they'll immediately be real helpful and say that whatever remodel you did, no matter how insignificant, was the problem. Stuff that we do without blinking causes PEMB's to fall down.
Be sure to remind the owner how much they saved on the initial building. Ask them to use that savings to pay you.
RE: Z Purlins - Revisited
Mike McCann
MMC Engineering
RE: Z Purlins - Revisited
RE: Z Purlins - Revisited
Thanks a million, dmoench01. Much appreciated
RE: Z Purlins - Revisited
Dik
RE: Z Purlins - Revisited
Even the flanges of some of the girders change thicknesses at quarter points....
Another odd item - the flanges of the built up sections (girders or columns) are only welded to the web on one side... You measure the depth on one side of the girder and its 28.75", and then 28.25" on the other.... and some of the webs are ultra-thin...
RE: Z Purlins - Revisited
RE: Z Purlins - Revisited
RE: Z Purlins - Revisited
- Shoot for 1.05 demand/capacity ratio
- Use an Fy at least 1.1*specified Fy
- Ignore any and all rational requirements on the strength of a brace to prevent LTB
- Be inconsistent in loadings so that purlins are continuous but loads to frames are based on simple spans.
I find if you do all that you can normally make them 'work'.
RE: Z Purlins - Revisited
Many of the metal buildings are descended from pole barns, which seem to work despite themselves. (Until they don't that is.)
RE: Z Purlins - Revisited
Mike McCann
MMC Engineering
RE: Z Purlins - Revisited
http://www.nwitimes.com/news/local/lake/crown-poin...