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CJP moment connection detail from HSS col to W-Flange beam

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SeizeTheMoment

SeizeTheMoment

Structural
Sep 16, 2020
25
US
Hello,

Does anyone know where I could find a reference for detailing a moment connection for a HSS column and W-Flange beam? I have through plates in the HSS col that's CJP welded with the moment beam flanges. I'm referencing AWS D1.8 for the weld access hole. Is there a reference for how the flanges should line up with the through plates? (i.e. how the the beam flange is supposed to line up with the top or bottom of the through plates, and how the backing bar is supposed to be lined up.)

I would think at both top and bottom flanges, it should be lined up so that the top of the backing bar is flush with the bottom side of the through plate and beam flanges.

The contractors erected it where the bottom of the backing bar is flush with the bottom side of the thru-plates:

Screenshot_2022-10-10_113204_gci7no.png


Screenshot_2022-10-10_113204_yn64je.png


I can't find a reference for this in AWS or AISC-341. If anyone has an idea, please let me know. Thanks!

Don't bend to the stress, seize the moment!

 
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The moment connection looks fine to me. The welds will be able to be filled and develop the beam flg. The part that stands out is the CJP of the HSS to internal backing ring. I've done a lot of similar (non-seismic) connections that look more like this, which eliminates HSS prep and backing:
Document1_v3rtgh.jpg
 
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@DrZoidberWoop, we have the 'backing ring' made of a solid plug of steel plate which eliminates discontinuities in the backing, which is necessary to eliminate weld discontinuities.

However, as you state, your detail is much easier to fabricate as a fillet weld can easily develop an HSS section. OP should refer to the AISC HSS Connection design guide for sizing welds.
 
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We specify a CJP connection around the HSS. I agree that it is probably overkill, and a fillet weld could have probably developed the HSS section.

Don't bend to the stress, seize the moment!
 
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I chose a poor image to capture this situation. Here's a better one. The beam top flange is about 1/2" higher than the column top plate. I don't think this weld will be able to fully develop the beam flange. They are proposing to PJP weld a plate on top of the column top plate.

Screenshot_2022-10-10_134628_hkmwis.png


Don't bend to the stress, seize the moment!
 
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Yuck, I am not convinced with the PJP weld of the new cap plate to the existing. Not to mention the fact that the CJP weld from the beam to the columns will be welding to this PJP weld.

Would it be possible for them to cut off the existing cap plate and weld on a new cap plate of appropriate thickness to complete the CJP weld of the beam flange to the column?
 
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@SteelPE Yeah, unfortunately I think that's the route that we're going to end up going for... At least they haven't welded anything yet.

Don't bend to the stress, seize the moment!
 
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Is this AESS or something such that you can't run a flange plate over the top?
 
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I would make the plate a bit overly thick and centered on the beam flange if possible. This is to account for beam depth and out-of-square tolerances.
 
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