old pre-engineered building

huangyhg

old pre-engineered building
i have been looking at an old pre-engineered building with a logo on the exterior end wall ridge of rb.
does anyone know who this is? at least 30 years old or more.
i would like to find out the live load capacity of the roof. can anyone recommend an approach? it has the tapered, sectional moment frame and cold rolled z purlins. my past experience in trying to analyze these frames has not been good. any help is highly appreciated.
lb
sorry to break the bad news to you, but even if the company was still in business, the calculations are long gone.  the roof is probably designed for 20 psf and not an ounce more.  you might be able to verify this using rigid frame analysis or a computer program if you could get the member sizes.
jed is probably right - but the capacity of the roof might be a bit higher if you are in a higher snow load area.  check local codes - but like jed said - it might - maye be good for one pound more??
and yes - good measurements and a software program is probably the only way to analyze this.
i am currently working on a similar building. i was very fortunate in that the building was built in 1994 and i was able to track down the original drawings and calcs. these buildings are computer optimized for the most efficent use of steel. the 10,000sf building i am working on has 7 different gauges of z section on the roof! all the frames have custom sections. it would definately be a challenge to gather enough data to model without the original documents. good luck.  
suggest to contact butler manufactural co., which is a pioneer in pre-engineered building business. it might be able to provide good leads, or assistance in analysis.
if it's 30 years old, the yield strength of the steel might be no better than a36.  to be sure, you should have a testing lab pull some steel coupons to be sure.  that is what i had to do on a similar project and to my dismay i learned that the steel was only a7 (33 ksi).
maybe you should check out this site:
i generally consider these type of buildings as 'temporary'.
dik
robertson?
terms like "good measurements" and "getting member sizes" are much easier said than done.
if your structure is exposed, like in a warehouse for example, it won't be too bad.  if it's a building with interior office space that has interior finishes that hide and cover up the structure, you're looking at a lot of work.
i've been asked to determine the capacity of an existing pemb before (where the structure wasn't exposed) and it's usually bad news for the client.  unless they have drawings on the existing building (not generic architural drawings, but real drawigns from the manufacturer showing   
i've made this point in threads before, but i'll make it again:  when you choose a pre-engineered manufactured building, you'll get exactly what you ordered.  it will meet current code.  if you want to change it in the future, get out the money you saved on the pemb initially, because it's going to cost you that plus more.  a change might be as minor as a monorail, a mezzanine or a roll-up door.  but it will be messy and expensive.