1950's Rebar Yield Strength
1950's Rebar Yield Strength
(OP)
I am working on the renovation of a cast-in-place concrete structure that was built in 1953. I have partial original construction drawings but, unfortunately, the drawings I have do not indicate the yield strength of the reinforcing steel. Based on research I have conducted, including reviewing ACI 318 in effect at that time, it seems likely the reinforcing steel is ASTM A15. This is helpful but ASTM A15 was available in 33 ksi, 40 ksi, and 50 ksi strengths. Does anyone know what reinforcing yield strength was typically specified in the early 1950's? Using fy = 33 ksi, some of the existing members do not 'work' so I suspect the actual yield strength is greater than 33 ksi.






RE: 1950's Rebar Yield Strength
RE: 1950's Rebar Yield Strength
When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.
-R. Buckminster Fuller
RE: 1950's Rebar Yield Strength
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RE: 1950's Rebar Yield Strength
Also, have you employed Live Load reduction in your calculations?
Mike McCann, PE, SE (WA)
RE: 1950's Rebar Yield Strength
Also...if you have 2-way slab or other condition that is more complex that simple one-way bending, all kinds of "assumptions" about behavior could have been used for design that might or might not model actual behavior reasonably.......or, more to the point, might not match whatever analysis model you are using now.
John F Mann, PE
www.structural101.com
RE: 1950's Rebar Yield Strength
How much overload are you calculating using Fy = 33ksi?......if "small" percentage (say, 15% or so) I would not be particularly concerned, especially if reality of full design live load is rather remote.
Consider also that as-built locations of flexural bars within depth of section may not be all that close to position specified in original plans....or your assumptions. Check sensitivity of analysis to variations in "d" dimension.
John F Mann, PE
www.structural101.com
RE: 1950's Rebar Yield Strength
PS: Price was $1.00 and it was 75 pages long (6" x 8").
gjc
RE: 1950's Rebar Yield Strength
Check very, very carefully, but don't miss the simple possibility of an error when fully analyzed with today's tools. That is, is IS slightly understrength to today's requirements A factor of safety is just that = The actual day-to-day loads may not have ever been high enough (after all assumptions are made) to "break" what seems too lightweight.