huangyhg

reinforcing steel in old drawings
i'm doing analysis on an old bridge, designed in 1954. there are only few lines on this plan as for "general notes!". when it comes to steel and concrete, it says
" reinforcing steel to be hard grade for columns and intermediate grade for all other locations."

now my question is what are hard and intermediate grades?! what is fy?
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)
the old aashto "manual for maintenance inspection of bridges" provides the following guidance for allowable unit stresses in tension:
structural or unknown grade prior to 1954: 18 ksi for inventory rating and 25 ksi for operating rating.
grade 40 billet, intermediate, or unknown grade (after 1954): 20 ksi for inventory and 28 ksi for operating.
grade 50 rail or hard: 20 ksi inventroy and 32.5 ksi operating.
what are you upgrading? structural steel, piers, footing, deck?...

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