1940s rebar fy

huangyhg

1940's rebar fy
i am looking at a reinforced concrete building from the 1940's. the drawings indicate fs = 20 ksi. until we have the rebar tested, i planned to use fy = 30 ksi to run preliminary numbers to estimate the loads this building can carry.  
does anyone have experience with rebar of this vintage? what values of yield strength should we expect?
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i would probably use 33 ksi if deformed bars. it could be well above that if it is either rail steel or square twisted (cold worked).
don't forget if your tests confirm a higher yield you may still have a development problem if your bars have the low deformation ribs of the 40's.
check out this paper.
good paper, structuraleit, i'll post it on my website.