grade of rebar in the 1940's
grade of rebar in the 1940's
(OP)
Hello All;
I’m currently reviewing a concrete floor slab (elevated) from the 1940’s. Does anyone have any information regarding reinforcing rebar back in the 40’s? The rebar schedule is calling off 1” square and round bars. Were there standards for rebar back then because I have never heard of square rebar. Specifically, I am looking for the minimum yield strength. Today’s bars are typically 400MPa (60,000psi). What grade would we be looking at back in the 40’s?
Thanks,
Mark.
I’m currently reviewing a concrete floor slab (elevated) from the 1940’s. Does anyone have any information regarding reinforcing rebar back in the 40’s? The rebar schedule is calling off 1” square and round bars. Were there standards for rebar back then because I have never heard of square rebar. Specifically, I am looking for the minimum yield strength. Today’s bars are typically 400MPa (60,000psi). What grade would we be looking at back in the 40’s?
Thanks,
Mark.






RE: grade of rebar in the 1940's
"Structural" Grade: 33 KSI
"Intermediate" Grade: 40 KSI
"Hard" Grade: 50 KSI
I would suggest using 33 KSI, unless you have reason to know otherwise.
Many rebar sizes were square until the 1940's. In fact, the legacy of that remains in use today with the crossectional areas of larger rebar sizes being fixed and the diameters being back-figured. This is easier to explain with examples, consider the following:
#9 Bar with area of 1.00 sq. in. = area of 1 in. square bar.
#10 Bar with area of 1.27 sq. in. = area of 1 1/8 in. square bar.
#11 Bar with area of 1.56 sq. in. = area of 1 1/4 in. square bar.
#14 Bar with area of 2.25 sq. in. = area of 1 1/2 in. square bar.
#18 Bar with area of 4.00 sq. in. = area of 2 in. square bar.
www.SlideRuleEra.net![[idea] idea](https://www.tipmaster.com/images/idea.gif)
RE: grade of rebar in the 1940's
See attached for various ASTM reinforcing bar yeilds through the years.
SlideRuleEra:
That is interesting about the square bars.
I learned something new today.
RE: grade of rebar in the 1940's
ikjh345: What publication is that from?
Thanks again.
Mark.
RE: grade of rebar in the 1940's
Always wondered why the 1/8" convention stopped at the number 8 bar, just never asked. Very interesting.
RE: grade of rebar in the 1940's
Mike McCann
McCann Engineering
RE: grade of rebar in the 1940's
RE: grade of rebar in the 1940's
RE: grade of rebar in the 1940's
Mark.