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RE: Residential Steel Detail

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One possible problem is that the supporting beam may be loaded slightly eccentrically, leading to some torsion acting on the beam. Even worse is that the connection detail doesn't provide much resistance against the supporting beam rotating about its axis (bottom flange kicking out). But this could be addressed by field welding (or bolting) an angle to the webs of the two beams
 
 

   Tom Barsh, P.E.
   Technical Support Engineer
   Codeware Inc
   www.codeware.com
 


From: S. Gordin [mailto:mailbox(--nospam--at)sgeconsulting.com]
Sent: Thursday, June 02, 2005 10:06 AM
To: seaint(--nospam--at)seaint.org
Subject: Residential Steel Detail

Good morning, fellow engineers.
 
In my experience, the use of structural steel in residential construction - particularly, in remodeling, is always somewhat tricky because of the different tolerances - demanding for steel and quite relaxed for wood.  Field welding, burning, cutting, etc. are as frequent as they are undesirable. 
 
So, designing the intensive remodel of a 3-story residential house, I came up with this detail.  Imagine two identical wide-flange floor beams connecting at a "T."  The reactions are low for steel (say, 6K).  The standard detail is to weld a tab to one beam and to cope/bolt the other.  Due to the above considerations, I thought of shop-welding 12"L x 8"W x 3/4" plate flat to the top flange of the supported beam (5" overlap, all-around weld).  The plate then simply bears (1" max. gap, 6" overlap) on the top flange of the supporting beam, transferring the reaction to its centerline.  
 
Both beams are nailed to the floor diaphragm through the bolted nailers (except at the plate location), and "are not going anywhere."   Construction-wise, the connection appears perfectly "flexible."  Structurally, the deflections are negligible, the stresses in the plate and beams are moderate, the weld is at about 30% of the allowable stress.
 
I am still uneasy with the detail.  What do you think?
 
TIA,
 
Steve Gordin, SE