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Tube to WF Connection

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vvaccare

vvaccare

Structural
Jan 3, 2014
18
US
Good morning all,

I am working on a connection design for a tube beam framing to the web of a wide flange column. The connection is to be designed to take shear, moment, axial, AND torsion. AISC does an excellent job detailing moment connections for wide flange beams framing to tube columns, however I am having a difficult time finding any examples for tubes framing to wide flange columns. I've gone through the AISC 13th edition steel code, as well as the little black connections manual for hollow structural sections. I have attached a sketch of the connection that I think may work, but I was hoping to get some feedback.

My thought process is that the plates on the top and bottom of the tube can be used to transfer the moment back to flanges of the column, while being used to stabilize the tube (similar to welding an angle to the top of the tube to stabilize it). The gusset plate on the bottom would also act to stiffen the bottom plate, to help in shear. The top and bottom plates will also be designed to take the force from torsion, and the welds (perpendicular to the tube and connecting plates) would essentially be designed to take the equivalent shear force from the torsion.

I apologize if this post repeats an older post. Any help or tips would be greatly appreciated.

Thanks!!
 
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Are you sure you want to put a moment into the weak axis of the column? Can you turn it 90 degrees for strong axis orientation? It will make those connections a lot easier also.

Also, it looks like you have diagonal braces above and below, do you need this tube to have moment-resisting connections?
 
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Thanks for the quick responses. Unfortunately, I am not able to rotate the columns to allow the tube beam to frame to the column flanges. This is a detailing job, and the structural EOR for the job has specified the beams to frame to column webs. I am trying to help our detailer out with these connections, because our detailing program is having issues generating these types of connections.

There are diagonal braces above and below, and this specific beam does not need to have a moment-resisted connection. There are other instances on the job where the EOR has specified moment connections, however they do not have diagonal braces framing to them.

Thank you again.
 
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Have to wonder why the EOR designed moment frames with the columns in the weak axis. Moment frames in both directions maybe? If it is me, I would double check with an RFI to the EOR on this.

Either way, the top and bottom faces of the HSS have to transfer the tension/compression couple into the WF column, which in the weak axis of the column, this will have to be into the flanges. This may be accomplished via plates which are welded to both flanges and then the top/bottom of the HSS.

 
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looks good as long as you can get in there and weld which it looks like you can. You also need an end closure pl on each end of the HS to make it effective in transferring torsion...it will also help the HS
in bearing ...you can add these closure pl's ahead of time...
 
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Thanks everyone for all the help! It's always nice to get someone else's perspective.
 
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Often times, an architect can be blamed when moment connections must be made to a columns weak axis. Other times, it is the most efficient method to design the structure.

Anyway, I am not thrilled with the proposed connection for a couple of reasons. Since the beam is in between the column flanges, the top horizontal (paddle?) plate and gusset will probably need to be field welded. The erector may ask if the beam can be shortened. Also, the shear forces will be transferred by the beam bearing on the bottom horizontal (paddle?) plate. I can't say the connection is bad - I am just not thrilled with it.

If the loads are high. I might consider a plate welded on the end of the HSS with shear tab welded onto it. Then connect it to the column similar to a W shape into the columns weak axis.
 
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wannabeSE, while I like to blame architects just as much as everyone else. I believe the engineer is just as much to blame with this connection (if not more) as the architect. Too many times the engineer will not think about what happens to the connections when they are coming up with the framing for the building.... or not work with the architect to achieve a simpler connection. "Let the detailer worry about it."

However, I do agree with you in regards to the erection of the connection. You are not going to fit that tube in-between the plates and flanges at the same time. The plates need to be extended past the flanges to get the connection to work..... or the top plate needs to be field welded (and with a brace/gussets I would not recommend this).
 
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If you have moment frames in both axes, then why not use a HSS column instead of the WF. This is why the EOR is to blame IMO, the architects rarely care or know how a column is oriented.

How about: bottom part of the connection consists of a horizontal plate for bending transfer, and a vertical plate to stiffen this into a seated beam type connection for gravity loads (T shape). These can be shop welded. Then the top plate for the moment connection could be field welded to the column flanges, and hopefully one good fillet weld would work across the outer edge of the plate to the top and bottom of the HSS to transfer your T/C couple forces from the moment.
 
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