yield stress for old reinforcing bars
 

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