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RE: Old Joist Type

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I have seen a lot of different bar joists over the years.  There are some 
questions that may narrow your search and lead you to an answer.  It may or 
 may not have been an SJI manufacturer.  . 1.  In what geographic area is 
the building located? 2.  About what year was the building constructed? 3. 
What kind of bridging does it have?

Bar joists are designed as simple trusses for gravity loads.  In more 
recent years wind uplift has been a design issue.  However, I was putting 
wind uplift diagrams on drawings in the 1980's when I wanted to assure that 
 my career would not be ended by a wind storm and a lawyer.

If the joist was pre 1970, it was likely Fy = 36 ksi.  After 1980, it was 
likely Fy = 50 ksi.  The 1970's were a transition period.

It could be that you might not find a joist manufacturer.  It may have been 
 built by a steel fabricator.

OK after all of that, the easiest thing to do is to fill out the SJI Joist 
Investigation Form:
Let SJI determine the most likely joist.  You should provide all of the 
measurements and the orientation of the W shape chords.  The chords will 
dominate the effective moment of inertia.

SJI also publishes the Tech Digest 12 - Evaluation and Modification of Open 
 Web Steel Joists and Joist Girders.

Regards, Harold Sprague

> Date: Wed, 19 Sep 2012 15:59:37 -0700
> From: dp_enco(--nospam--at)
> Subject: [SEAINT-SEAOSC] Old Joist Type
> To: seaint-seaosc(--nospam--at)
> I need to determine joist property with following members.
> Top & bottom chord: W shape, 5- 1/2"x1".
> Digonals 1" diameter pipes, crimped at panel points., 30" c/c panels
> points, no verticals. About 30" jost depth, 40' joist span, 5'-0" o/c
> spacing, Roof joist.
> It appears propriety shape, not listed in SJI 60 year manual.
> Anyway to locate manufacturer to determine proprties.
> Thanks.
> Dilip Patel, PE

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