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Concrete Compressive Strenngth and Rebar yield strength for 70's Bldgs

Concrete Compressive Strenngth and Rebar yield strength for 70's Bldgs

Concrete Compressive Strenngth and Rebar yield strength for 70's Bldgs

(OP)
Can somebody direct me where to find out the typical Compressive strength and yield stress for a r/c structure build in early 70's?

Can't find these information on the drawing or elsewhere?

How can I get these info?

Thanks

RE: Concrete Compressive Strenngth and Rebar yield strength for 70's Bldgs

The concrete compressive strength could be anything. If you've had a chance to see the concrete in person, or via photos, then maybe you can get a feel for its condition. Presuming it's not crumbling, I often use 2500 psi when I don't specifically have data, knowing that there is a high likelihood that the strength is higher.

Some very old reinforcing bars had Fy = 33 ksi, but I believe that was largely phased-out before the end of the 1960's. For a building of your era, 40 ksi bars were common. There is a chance the Fy is higher such as 60 ksi, but I wouldn't assume that unless you have specific data or testing.

RE: Concrete Compressive Strenngth and Rebar yield strength for 70's Bldgs

Assuming in the USA correct? Please verify that.

In the US, 1970's Nor Cal SE is correct on the rebar fy - I'd assume 40 psi.

For concrete - you can sample and test the concrete by taking cores. You are probably going to find that the f'c specified was at least 3,000 psi if not 4,000.
In some cases concrete columns were kicked up a bit - perhaps to 5,000 psi or 5,500 psi but I wouldn't just assume that without testing. Depends on the size, height, etc. of the building.


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