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Re: Column Web Doubler Plate on both sides

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In a message dated 97-08-17 06:54:06 EDT, you write:

<< Subj:	Column Web Doubler Plate on both sides
 Date:	97-08-17 06:54:06 EDT
 From:	kassamem(--nospam--at)aramco.com.sa (Eqbal M. Kassam)
 Reply-to:	seaoc(--nospam--at)seaoc.org
 To:	seaoc(--nospam--at)seaoc.org
 CC:	SpragueHO(--nospam--at)bv.com
 
 To satisfy seismic panel shear requirements and utilize existing steel
 stock the local contractor is proposing to use columns with thin webs
 and reinforce it with doubler plate at both sides of the web. This is at
 the moment connections and specifically to satisfy seismic column web
 shear requirements. The site is in High Risk Area (UBC Zone 3).In some
 cases, doubler plates thicker than column web is welded on both sides.
 
 I think this is fundamently incorrect and there may a lot of welding
 problems associated with doubler plates on "BOTH" sides of a thin column
 web. Previously, I have used doubler on one side only and also the
 literature shows doubler plate on one side only.
 
 Folks, what are your views ? Is the contractor technically incorrect and
 why? Are there any welding related problems? I sugested to the
 contractor to use "Haunches" but see some resistance. Also, I believe,
 according to Blodgett, there are also welding problems with welding
 doubler on one side only.Any comments?
 
 Thanks
 
 Eqbal M Kassam
  >>

Eqbal,

Check the latest SAC guidelines regarding using doubler plates.  I have been
told by fabricators it is significantly cheaper to increase the column
weight, than to have to weld doubler plates to a lighter column section.  If
I remember correctly during the Northridge Earthquake, in one building there
were columns with doubler plates that still had cracks develop in the column
web and not the doubler plates on each side of the column.  I would tell the
fabricator he needs to buy a larger column instead of using existing steel
stock.

Michael Cochran