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RE: STEEL: Welding of Steel Bar Grating

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The practice of my firm is to not consider grating as bracing for the compression flange or top flange of a bar joist. Additional bracing is required. Intuitively, I know that the grating provides some degree of bracing, but grating has never been tested nor quantified in regard to in plane loads.

One of the desirable features of grating is the ability to EASILY remove it to access what is below. Welding grating is ugly, and does not allow easy removal of the grating. Actually it is better, cheaper and easier to use the powder actuated grating fasteners like those that Hilti uses.

Another consideration is the strong tendency for welders to cut the relatively thin sections that comprise the top chords of bar joists. It is called "undercutting" or "cratering". This is common on welds perpindicular to the chord.

(Note to self: Hilti owes me a beer.)

Regards,
Harold Sprague


From: Bill Polhemus <bill(--nospam--at)polhemus.cc>
Reply-To: <seaint(--nospam--at)seaint.org>
To: seaint(--nospam--at)seaint.org
Subject: STEEL: Welding of Steel Bar Grating
Date: Thu, 03 Feb 2005 06:32:26 -0600

I want some other opinions--I've already formed my own.

I've got a contractor who in erecting an open-web steel joist-supported floor welded the steel bar grating to the tops of the joists (i.e. the top chord) with little fillets (essentially fat tack welds). He claimed that he "likes that better" than any other method including saddle clips.

Seeing as how the grating isn't directly a structural item, I forebore comment (though I think it's a sloppy method of attachment myself). But I pointed out that he had not provided additional bridging for lateral stability as I had expected to see, and as I had implied ought to be provided by notes on my drawings (that is, I indicated on the drawings that the steel joist fabricator should provide means for lateral stability as they deemed necessary since the bar grating would not be considered as providing lateral support).

The contractor replied "well, that's why I welded the grating! You can't tell me that's not sufficient support!"

Of course I can, and I did. I tried to be diplomatic about it, saying that I did not think the fabricator would agree with him. His response was that he'd "get a letter from the joist fabricator stating that it was all right."

Still haven't seen such a letter going on the second week. Has anyone run into anything like this before? Implicit in the presence of the welded grating is the notion that certainly some lateral stiffness has been provided, but I don't believe that I've ever seen any provisions or any research to suggest that this is sufficient.

Chime in if you would.

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