old roof purlin material

huangyhg

old roof purlin material
i am looking at the load capacity of roof purlins on a pre-engineered metal building. the building was constructed in the early 70's. the metal building company no longer exists and the city and owner do not have drawings. what i need to know is what was the predominate steel material used. does anyone have any idea where i can find this info?
why don't you contact a few pre-engineered building companies e.g. butler buildings, varco pruden, american, etc. and ask what they were using in the 70's?
good luck
beamer,
you can check fema 273 for prevailing material properties during that time; however, this is still an assumption.  i personally would tend towards material testing.
i would definitely call existing metal building companies. also mbci (metal building components inc.) and check with them. a search in published data circa 1970 could shed some light on the predominant material used for purlins.
one of my favorites is to find an older engineer and ask him. these guys are wealth of information and always love to help.
last but not least, look on the internet. you will be surprised on how much you will find.
good luck.
sorry this is so late, but i just ran across this thread.  how about trying a call to american iron and steel institute (aisi)? they produce the cold-formed steel design manual and may have design values and section properties from back then.  
of course you can also field measure the purlins and calculate the section properties.
i worked on two older metal buildings a 1965 star building and a 1973 butler building.  first of all, i did know who the manufacturer was, so that did help.  but, the engineering departments at both manufacturers were also very helpful.  they were using 50 ksi steel for all cold rolled members and some built up   
as per fema 273 para 5.2 (historical perspective-steel and cast iron), the material used in older construction is likely to be mild steel with a specified yield strength between 30 ksi and 36 ksi.  from table 5-2, structural steel dated 1961 and on have an expected yield strength ranging from 30 ksi to 46 ksi.
i ended up using 30 ksi for the steel material. i did talk with a couple of "experienced" engineers and they both agreed that 30 ksi or 36 ksi is probably what was used, but they also said that that was, at the time, the lowest strength steel used at the time. i felt pretty good using 30 ksi.