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RE: STEEL: Welding of Steel Bar Grating

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I would be willing to consider welded grating as lateral support for the
top flange, provided that I had some control over the no. and size of
welds as well as weld quality. I would not consider tack welds adequate,
and I would still require bracing of the bottom flange if subjected to
compression at the bottom flange. 

But I also agree with Harold that I generally try to avoid welded
grating and only use it when so requested by the client. 


William C. Sherman, PE 
(Bill Sherman) 
CDM, Denver, CO
Phone: 303-298-1311
Fax: 303-293-8236
email: shermanwc(--nospam--at)cdm.com
 

> -----Original Message-----
> From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com] 
> Sent: Thursday, February 03, 2005 11:39 AM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: STEEL: Welding of Steel Bar Grating
> 
> 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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