When was A36 steel introduced? 1

[apetr26542]

Analyzing roof of building constructed in 1966 for mechanical unit addition, have plans with sizes not grade, I thought it was in the 1950's. But was it used widely enough in 1966. I have a sixth addition AISC Manual (1963) it lists both 33ksi and 36ksi. I may end up using 33 ksi to be conservative, but now I am curious.

 

[JStephen]

ASTM-A36 was "originally approved in 1960", per the footnote in the current A36. Actual usage could have lagged behind, I suppose.

 

[apetr26542]

Yes, similar to our A992-Gr50.

 

[archeng59]

apetr26542, great question. I just reviewed the floor framing for a mechanical room in a building constructed about the same time as yours. I used the 33 ksi steel just to be conservative.

 

[HgTX]

From

http://www.usace.army.mil/usace-docs/eng-manuals/em1110-2-6054/c-7.pdf

In 1939, A7 and A9 were consolidated into a single specification, A7 steel (ASTM A7-39) for bridges
and buildings, which then became the single specification for structural steel. In 1954 a new structural steel for
welding, A373 steel, was introduced (ASTM A373-58T). Both A7 and A373 steels were consolidated in 1965
into one specification, A36 steel (ASTM A36-60T), which is the basic structural steel today and is used for
both welded and bolted applications.

During the same period that A7 steel was evolving, the American
Institute of Steel Construction (AISC) changed their basic allowable working stress for structural steel only
once, raising it in 1936 from 124 to 138 MPa (18 to 20 ksi) (Ferris 1953). The ASTM requirement for
minimum yield point during this period was generally one-half times the tensile strength, or not less than
207 MPa (30 ksi); in 1933, the minimum of 207 MPa (30 ksi) was raised to 227.5 MPa (33 ksi) for plate and
shape products. When A373 steel was introduced, that steel had a minimum yield point of 220.6 MPa (32 ksi),
suggesting that to improve weldability at that time, some sacrifice in strength was necessary. Only when A36
steel was introduced in 1960 in a tentative specification (ASTM A36-60T) did the minimum yield point for
structural steel plates and shapes increase to 248 MPa (36 ksi). By that time, weldability and welding practices
for structural steel had markedly improved and standardized.