I am investigating an existing precast, prestressed double tee roof constructed in the late 1950's
I'll be x-raying the members to get strand diameters and locations.
Any ideas as to the likely yield strength of the strands?
I'm guessing 270k strands were not available at the time, and if...
Has anyone run across the designation FK18-18 (or 10-10) @6.7 PLF (or 18.5 PLF) for a cellular (i.e. castellated) steel beam - circa 1940's - midwestern US