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Mill Certifications

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These remarks come from an avid seminar attendee and reader of published
information, I do not do much steel design other than a occansional light
Rw=4 steel frame in retrofit situations.

Attendence and reading has revealed to me a potention problem in design and
mill certification yield values.  Most of this information comes from the
recent SAC ( "SEAOC" Structural Engineers Association, "ATC" Applied
Technology Council and "CUREE" California Universities for Research in
Earthquake Engineering) publications.  

The SAC Project is a result of the 94 Northridge Earthquake and the
problems found in buildings that were designed and constructed in
accordance with the AISC recommendations as well as the AWS standards.

Information provided in the SAC recommendations include what does the
uncertainity of yield strength do to welding and the cyclic loading of
welded full penatration connections?  

How does the variable yield stress of each component effect analysis,
especially extensive numerical analysis by computer?  

What is the uniformity of the material throughout the element and how does
the mill certification reflect the differing materials, strengths,
stiffnesses and yields throughout the entire element?

Does a yield stress above the anticipated level really be considered a
factor of safety or another independent variable that could be good or bad
depending upon individual situation?

Does an element that has variable mill ceritifcations by element,
constitute a concern for the mill certification for the material throughout
one element and if it does not, are the basic assumptions for materials
from strength of materials valid?  Isotropic?  

For those asking these questions, I recommend reviewing the SAC documents
for a more experienced review of the subject matter.  These documents can
be obtained by contacting the Applied Technology Council in Menlo Park, CA
(near San Francisco).

	Bill Warren, SE
	Newport Beach, CA