Return to index: [Subject] [Thread] [Date] [Author]

Re: Residential Steel Detail

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Bruce,
 
The beam is neither moving up (the dead load holds it down at any time), nor is shifting in the floor plane due to the diaphragm nailing.
What would be the purpose of the (4) bolts?  Among other things, the bolt holes will take away from the capacity of the supporting beam at the location of the maximum moment.  
 
Zipping of the weld definitely came to mind; however, the absence of the "fourth" weld, appears to make this problem worse, not better.  Besides, "zipping" is only a matter of stress, right?  Even considering the weld notching, the stresses in the weld and in the plate are quite low, and welding will be done in a controlled environment of a shop.
 
Steve Gordin, SE 
 
 
----- Original Message -----
Sent: Thursday, June 02, 2005 9:26 AM
Subject: RE: Residential Steel Detail

Seems like an unusual detail for steel beams, but sounds similar to a joist header detail I remember in the Vulcraft steel joist manual.  I would be concerned about notching from the all-around weld and from the weld ?unzipping? at the edges of the plate if you don?t weld all-around.  I?d recommend connecting the plate to the top flange of the supported beam with (4) 5/8? dia. A307 Bolts.  Field weld to the top flange of the supporting beam with 3? fillet weld on 3 edges of the plate. 

 

 

Bruce D. Holcomb, PE, SE

 

 

-----Original Message-----
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