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RE: Existing steel joist manufacturer?

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Phil,

One thing you forgot to mention was that the joist tag was usually used as a
mark number.  Referring to the book written by Fisher, West & Van De Pas,
"Desigining with Steel Joists, Joist Girders, Steel Deck", the authors
write:

"It may be possible to determine the joist designation from the joist tag.
Each joist is supplied with a tag at one end.  This tag is intended to mark
specific joist for erection purposes.  The manufacturer will provide an
erection plan that indicates where each joist is to be located.  The joists
are identified on the plan by the mark on the tag.  Besides the mark number,
the tag may also indicate the joist manufacturer."

Sounds like the manufacturer is unknown, so trying to tie the mark number to
any shop drawing can't be done.  I'd ask the current building owner, or past
owners if they are aware of any old drawings located anywhere.  I'd also see
if the original design drawings (which indicate you designed the building)
are available anywhere.  If they are still in business they may have some
old project files that indicate who provided the joists on the job.  Just
some thoughts....

Robert C. Rogers, PE
robert.rogers(--nospam--at)woolpert.com


-----Original Message-----
From: Philip T. Hodge [mailto:phil(--nospam--at)joistdesign.com]
Sent: Sunday, April 09, 2000 8:42 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Existing steel joist manufacturer?


Dan:

There is no way to read the tag and definitively know anything of value
about the joist.  If the joists were fabricated by a member of the Steel
Joist institute then the name of the manufacturer would be embossed on
the tag.  If these joists are 24" deep then you know that the first
number probably corresponded to the depth.  If they are some other depth
then it doesn't.  There never was any standard for tag information.

But even if you have that, you would need to know when that particular
manufacturer switched from two different grades of steel (36 and 50) to
only one before you'd know for sure what you had.  Several manufacturers
used 50 ksi steel in J series joists, and just gave away the extra
strength.  Conversely, some tested each heat, and used the test value
for Fy, thus robbing you of some of your reserve.  It is unlikely a
different grade of steel was used in the top chord from the bottom
chord.  It is also unlikely that web members would be fabricated from
different grades of steel.  However, the chances that the chord steel is
different from the web steel are fairly high, particularly with cold
formed chords as you describe.

The top chord is usually larger than the bottom.  Thickness and/or strip
width will change from one to the other.  It is also fairly common, but
not universal in that era, for joist webs to decrease diameter from the
end towards the center.  Not continuously, but expect one or two
changes.  So be very careful when you measure, and don't assume that a
standard gage or diameter was used - the joist manufacturers have often
had large enough orders (or owned their own mills) to get custom sizes.

Good luck, have fun with your micrometer, and get the SJI's 60 year
digest.  If you need any additional help, write me.

Phil Hodge
phil(--nospam--at)joistdesign.com