Welded Extended Web Beam Connection 1

[oth1]

I have been faced with this problem many times, designers specifying beam to beam connections for equal sized beams with both flanges of the incoming beam coped, with only the flat portion of the web extending to meet the web of the continuous beam, and connected with a double fillet.

I see two problems, one, concentrated stress at the top and bottom of the framing beam web where it connects to the web of the continuous beam, and two, a shear buckling weakness in the extended web tab.
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I cannot find any reference for calculating the buckling capacity of the shear tab, where two edges are supported and two are free.

Any suggestions?

 

[rob768]

I how seen this often too, but usually only in the horizontal connections, where buckling load is less critical. I've never seen it in a vertical connection. Personally, I would weld the flange interfaces as well, creating a more stiffer connection.

 

[trainguy]

This is a situation that should simply be avoided; that is why you have not found a reference. I believe using a double angle web connection should help get rid of the potential (almost certain) instability you have correctly spotted.

tg

 

[oth1]

I have avoided it in the past, but when you start at a new company and they have "standards" which show these connections, just saying "I don't like it" is not enough, it seems to me the shear buckling equation applies, but every reference I have for the buckling contant value assumes at least three of the edges are some how supported, I have not seen one that gives a value when only two are supported.

 

[Taro]

I try to avoid this detail for economic reasons, but this is a fairly common condition in steel structures. For design procedures, see AISC 3rd edition LRFD manual p.9-7. But note that there are a few errata for this section (depending on which printing you have).

 

[dbuzz]

How about detailing the connection with compensating flanges at the copes? This is not uncommon in heavy mining and industrial structures.