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Re: ASTM A36

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In a message dated 11/4/98 3:55:09 PM EST, hhuang(--nospam--at)co.la.ca.us writes:

<< 
 ASTM A36 is still available and is likely to be available for W-shapes for a
 long time in the future, but this depends on the demand.  As long as our
 customers continue to order it, we will produce it.  ASTM A36 is considered
 the "base grade", in which a shape producers' price list is based.  Grade
 extras are added to the base price in many cases depending on section size.
 In the case of ASTM A36 and ASTM A572 Grade 50, many of the sections produced
 are considered "multi-certified" because they meet both specifications.
 Generally speaking, this is up to about the W24x162 section/footweight, where
 the price is the same for both ASTM A36 and ASTM A572 Grade 50.  With thicker
 and heavier footweight sections, there is a need for additional alloys to
 provide the specified strength levels, so there may be a nominal "extra" for
 these sections.  A quick look at our price list can determine which sections
 are "multi-certified" and which are not.  
 
 In addition to ASTM A36 and ASTM A572 Grade 50, the CSA 40.21 Grade 50W is
 also included in the multi-certified grade for the same reason stated above,
 it meets that specification too.  
 
 In May 1998, ASTM approved the new "Enhanced ASTM A572 Grade 50" for (W-
shapes
 only), however, we are still awaiting ASTM to formally announce it and make
 the new specification available to the public as a separate specification.
We
 understand it is due out from ASTM within the next few weeks.  As an interim
 step, until the grade is officially announced (we believe it will be listed
as
 ASTM A992) and approved by the various spec bodies, the "enhanced" grade 50
 can be specified in accordance with the AISC Technical Bulletin # 3 (March
97)
 which is available from the AISC web site.  This "enhanced" grade, meeting
the
 proposed specification, has been available within the past two years from NYS
 and other major shape producers, as ASTM A572 Grade 50, because it is, in
 fact, that grade but more "enhanced" (more restrictive spec criteria).  
 
 We understand more designs must be using a single-grade (Grade 50) design
 rather than using two distinct grades (Grades 36 & 50) based on an increased
 demand for ASTM A572 Grade 50 and less demand for ASTM A36.  Eventually, we
 may see the ASTM A36 grade disappearing for wide flange structural shapes,
 however, this may take a long time to happen.  Again, in the meantime, ASTM
 A36 is available by most, if not all, shape producers even though in some
 cases it may be considered a multi-certified steel grade.  And once again, it
 is suggested that the Enhanced ASTM A572 Grade 50 in accordance with the AISC
 Technical Bulletin # 3 (March 97) be specified on projects whenever possible.
 
 Mike Engestrom
 Technical Marketing Director
 Nucor-Yamato Steel
 (301) 694-3067
 (301) 694-2349 FAX
  >>

Mike,

I have a couple of questions:

My understanding is that all structural shapes produced today in the U.S. for
ASTM A36 and A572 Grade 50 are made from scrap steel.  Since it is made from
scrap, the minimum yield typically for all shapes ( including angle, channels,
WT's, etc) is greater than 50 ksi eventhough these other shapes are still
referred to being ASTM A36.   For design of lateral force resisting elements
(braced frames, etc.) where shapes other than wide flanges may be used, should
the designer be considering that the actual steel yield for channels, angles,
etc is at least 50 ksi eventhough they would be specifing A36 for the
material.

I understand that a new proposed ASTM A992 is being developed for the wide
flange sections only.  Is it intended that angles, channels, etc will be
included within this specification in the future.

I don't know if NYS produces tube sections, but what would be the reasonable
expected yield of these members.  From the mill certs for rectangular tubes
(ASTM A500, Grade B, Fy=46 ksi) I have seen yield values ranging from 52 ksi
to 64 ksi with the average aroung 57-58 ksi.  I would assume for seismic
lateral design purposes (tension) that I should be using an average yield
strength of 57 ksi instead of 46 ksi.

Thanks,

Michael Cochran
Brian L. Cochran Associates
Los Angeles, CA