Rebar grade in 1920s?
Rebar grade in 1920s?
(OP)
I have a small renovation project from 1928. I can't find the material properties in the existing drawings. Would it be reasobale to assume f'c= 3000 psi, fy= 40,000 psi?
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
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RE: Rebar grade in 1920s?
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RE: Rebar grade in 1920s?
References from that era give material information as working (allowable stresses). For steel, the minimum acceptable stress was fs = 16,000. Steel varieties varied quite a bit, so it's difficult to be more precise than that.
For concrete, there also appears to be quite a bit of variation. I'm seeing numbers in the range of fc = 600-650, which is quite low. It might be worthwhile to perform a swiss hammer test instead of trying to guess at capacity.
This is from this book: http://books.google.com/books?id=ui5VAAAAMAAJ&... . Do a google book search on "concrete" or "reinforced concrete" between 1920 and 1930 for more (free!) references from that period.
Brian C Potter, PE
http://simplesupports.wordpress.com
RE: Rebar grade in 1920s?
RE: Rebar grade in 1920s?
I guess it would make sense to do some testing to figure out the existing capacities. I know they can do core samples for concrete, but is there a way to test the existing rebar?
RE: Rebar grade in 1920s?
I agree with the core. I've done some building renovation and learned concrete strength is over the place. Plans back then usually didn't specify f'c, they just went with a mix proportion. Same thing with old bridges.
RE: Rebar grade in 1920s?
Thanks.
RE: Rebar grade in 1920s?
Note also that if you do tests, you can't use the direct results of the test. The test will only help you ascertain which spec or grade you meet, or what ASTM spec you meet (if you use astm). Once you can evaluate the astm spec you meet, you can use that spec's minimum yield.
RE: Rebar grade in 1920s?
You are mixing allowable stress with yield stress. The yield is likely to be 33ksi. The bars are probably plain (undeformed) and may be square or round.
Tests can be done by removing a sample. I don't believe there is any test to determine yield for steel in place.
BA
RE: Rebar grade in 1920s?