Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: steel grades

[Subject Prev][Subject Next][Thread Prev][Thread Next]
On Oct 29, you wrote:


> I just received a call from a steel detailer concerning structural steel
> grades.  I was informed that the production of A36 steel is no longer.  I was
> told that Grade 50 steel is now being used instead of A36 steel
>
> Can anyone verify this information that I have received.
>

There has been a general trend over the last 10 years, towards a 
phase out of steel produced by so-called Integrated Mills, which use 
pig iron as the basic steel component, to the newer electric arc 
furnace based mills (so called mini-mills) that primarily use scrap 
steel as the basic steel component.  Today, nearly all domestic steel 
rolled into structural shape is produced by these newer mills.  The 
steel produced by these mills typically will meet both the ASTM A36 
and A572 specification requirements and will commonly be "dual 
certified" as meeting both requirements.  Steel which meets the 
specification of one but not the other, will be so certified.

As a result of these technological changes, there is no longer any 
significant cost difference between A36 and A572 and it appears that 
the industry is moving towards a gradual phase out of A36.  However, 
domestic mills will still deliver steel to an A36 specification (even 
if it also meets A572) and some foreign mills will also provide steel 
conforming to A36.

At the current time, there is no problem specifying A36.  However, 
you should be aware that the properties of the steel actually 
delivered to the project may also conform to A572.  This is 
particularly important for seismic applications.  As suggested in 
FEMA-267 and FEMA-267a, when designing connections based on the yield 
strength of the material, it should be assumed that 50 grade material 
will be present, even when 36 grade is specified.  However, if A36 is 
specified, member sizes should be proportioned, assuming 36 grade is 
provided.


Ronald O. Hamburger, SE
Regional Manager
EQE International, Inc.
San Francisco, California