Plate to HSS Tube Connection

Does anyone have a quick solution to attach the plate shown to the tube shown? Solution would include stability of the plate and effect of the moment from the plate on the HSS tube.

also posted on the other site.


Have you had a look at the CIDECT design guides. Design Guide 1 as joint capacity checks for longitudinal plates onto CHS sections.

There are also some old Corus publications (clause 5.1.7)

Is this the sort of thing you are looking for?

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There doesn’t seem to be anything stabilizing the plates.
Even assuming the PF is distributed equally to the 4 plates, there’s still a problem keeping them from collapsing without lateral support. The buckling resistance will be proportional to the thickness of each plate - but also dependent on the fixity to the tube.

Is PF large? I guess you wouldn’t ask if it wasn’t pretty high.

Can you consider adding parts to stabilize them? Gussets? Or perhaps a ring that rests on the top of all the plate edges, welded to them all so that at least the plates are constrained from lateral motion on the top edge, if still free to buckle on the bottom edge. That could at least double the buckling resistance.

Thanks for the caution. It’s not shown, but there are a couple of HP sections welded to the top of the plates. They provide the load and the support.


Wall of HSS would be related to plastification. I’d look at AISC chapter K table K2.1 (2018 version of the code).

Then for the plate capacity itself, there are some buckling equations for extended shear plates in the AISC manual. Unfortunately, I don’t have it with me now to point you to the exact spot.

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Thanks Josh… and welcome to the menagerie…

Ignore this response… this was for a different problem. I left the reply because it is an interesting solution to a totally different problem. I have some HSS beams connected to an HSS column with moments transferred to match the strength of the HSS 4x4 column. Moments are transferred through the column crown plate and the HSS beam bearing plates.

I could’t find any literature so have welded a plate across the end of the HAA with fillet welds to the sides of the tube and a fillet weld on the bottom to the thick plate. A fillet weld is placed across the top of the tube to seal it.

At the front edge of the HSS, two small ‘side’ plates are welded to connect the HSS sidewalls to the base plate. I was concerned about crushing the HSS at the front edge.

By connecting the HSS 5x5 to the 1-3/4" connection plate, I can transfer the equivalent moment of the HSS 4x4 column.

Crown plate on the column is the same thickness and the column is fully fixed to the crown plate.


Being at the top of the HSS, just weld up the tab plates in an “X” and insert into four vertical slots in the HSS, weld off, adding backer plates if desired to fill in slots above tab plates, and weld on top cap plate.

Thanks, Mike