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yield stress for old reinforcing bars
i'm evaluating some concrete beams that were designed in 1926. any idea what the yield stress for reinforcing bars from that era is?
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without any additional info. or rebar tests, i would not recommend using a yield greater than 33 ksi.
i suggest that you order a copy of "evaluation of reinforcing bars in old reinforced concrete structures", engineering data report number 48 by crsi.
grades:
structural 33,000 psi
intermediate 40,000 psi
hard 50,000 psi
my 1937 copy of trautwines civil engineers reference book gives:
"normal reinforcing steel ultimate strength of between 50,000 - 70,000 lbs per sq in with elastic limit (yield) at 25,000 - 35,000 lbs per sq in.
cold working the bars will raise the elastic limit to 40,000 - 50,000 lbs per sq in.
deformed bars have a higher elastic limit claimed at 50,000 - 65,000 lbs per sq in."
i pulled this information off the internet some time ago. it actually came from a post on eng-tips.
hope it helps.
per fema 356 table 6-1, rebar typically came in 3 grades prior to 1968:
structural: fy = 33 ksi, fu = 55 ksi
intermediate: fy = 40 ksi, fu = 70 ksi
hard: fy = 50 ksi, fu = 80 ksi
the following info is per crsi engineering data report no. 48:
hard grade is referred to reinforcing with fy = 50,000 psi. and fu = 80,000 psi.
intermediate grade is referred to reinforcing with fy = 40,000 psi and fu = 70,000 psi.
structural grade is referred to reinforcing with fy = 33,000 psi and fu = 55,000 psi.
these are tied into the following astm's:
1911-1966 - astm a15 (billet steel) (all three grades)
1913-1966 - astm a16 (rail steel) (hard grade only)
1936-1964 - astm a160 (axle steel) (all three grades)
i think you can get this document from www.crsi.org

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