What grade of steel used in PEMB Girts and Purlins - circa 1974?
What grade of steel used in PEMB Girts and Purlins - circa 1974?
(OP)
OK, so I am looking at a PEMB fire station where the original drawings are 1974. We have no info on the metal building itself, so I went out and measured everything. I am running the calcs now, but I need to know what grade of steel was commonly used in 1974 for cold formed C and Z girts/purlins. The oldest reference I have is a Star Buildings catalog from 1985 which lists 55 ksi as the yield stress for their girts/purlins.
Anyone know what was common in the mid-70's in the US? I don't have any contacts at any PEMB manufacturer, but will cold call a few if I need to. Thought I would ask here first.
Same question for roof and wall panels. We have pretty typical corrugated steel panels, 24 gage thickness.
The goal of the project is to determine what it will take to bring the building up to current Florida Building Code requirements. Right now, things are looking pretty good, amazingly. My main bents are only running at 75%, assuming Fy=36ksi. Roof purlins look pretty good (depending on Fy) for gravity, but need bottom flange bracing for wind uplift.
Thanks much.
Andrew
Anyone know what was common in the mid-70's in the US? I don't have any contacts at any PEMB manufacturer, but will cold call a few if I need to. Thought I would ask here first.
Same question for roof and wall panels. We have pretty typical corrugated steel panels, 24 gage thickness.
The goal of the project is to determine what it will take to bring the building up to current Florida Building Code requirements. Right now, things are looking pretty good, amazingly. My main bents are only running at 75%, assuming Fy=36ksi. Roof purlins look pretty good (depending on Fy) for gravity, but need bottom flange bracing for wind uplift.
Thanks much.
Andrew






RE: What grade of steel used in PEMB Girts and Purlins - circa 1974?
As far as your main task, its been covered many times on this forum. It's very tough to get into recreating PEMB work at all, much less 40 years old. Now maybe since the computer power wasn't as prevalent tehn, the calculations were more conservative than they are now, but I wouldn't be surprised if you eventually felt like you were beating your head against a brick wall. The fact that you aren't getting frustrated right away is a good sign.
Good luck.
RE: What grade of steel used in PEMB Girts and Purlins - circa 1974?
Fortunately (or unfortunately, depending on your perspective), I've done evaluations of a few PEMB in the past, so I have a pretty good approach worked out now I think. Yes, I have had problems with the more recently built buildings. Mainly, the problems I encounter are almost always unbraced length issues due to lack of bottom (or inside) flange bracing.
For this building I am reviewing now, I already know I will be adding bottom flange bracing on the roof purlins for uplift. I will also be adding sag rods to the girts, which the metal building industry allow for out of plane bracing of the unsupported inside flange of the girt.
But so far, the stresses on the overall sections are looking very reasonable. I haven't yet started looking at the connections or foundations. But my experience has been if the overall members are pretty good, then the connections are usually pretty good as well. Fortunately, there is no seismic requirement here in Florida, so that simplifies things a bit.
RE: What grade of steel used in PEMB Girts and Purlins - circa 1974?
I've got some existing PEMB reroofing in Florida. But we got the client to not make us check the building. We just have to provide a standing seam roof that meets current code.
RE: What grade of steel used in PEMB Girts and Purlins - circa 1974?
Was the original roofing standing seam? If not, your new standing seam roofing may not do the job of bracing the purlins.
RE: What grade of steel used in PEMB Girts and Purlins - circa 1974?
RE: What grade of steel used in PEMB Girts and Purlins - circa 1974?
RE: What grade of steel used in PEMB Girts and Purlins - circa 1974?
RE: What grade of steel used in PEMB Girts and Purlins - circa 1974?
Since your building seems to be working so well, perhaps it is not a PEMB after all, but rather one designed by a traditional consultant.
RE: What grade of steel used in PEMB Girts and Purlins - circa 1974?
RE: What grade of steel used in PEMB Girts and Purlins - circa 1974?
RE: What grade of steel used in PEMB Girts and Purlins - circa 1974?
RE: What grade of steel used in PEMB Girts and Purlins - circa 1974?