HSS Corner Weld Detail

[dozer]

I've attached two options for welding square HSS members of the same size together. I'm wondering which, if either, of the two options I show is most common. If neither, what's another option? In both options, you weld the first tube to the one I show in cross section using a flare-bevel weld. Now when you attach the third one you can no longer use a flare-bevel on the inside corner because you've welded shut your bevel. With option A you would do a bevel weld at the inside corner. This seems the most robust design but more difficult for the shop. With option B, the tube would simply be square cut and you would make a fillet weld on the inside corner. This is easier but it makes for strange goings on in the world stress right there.

 

[dik]

Can you re-load your sketch?

Dik

 

[berkshire]

Dik,
It was a PDF and the sketch is right at the bottom of the page, you have to scroll down to find it.
B.E.

You are judged not by what you know, but by what you can do.

 

[thaidavid40]

I don't know the load types or load levels you are trying to carry here, but in the second Option B, the first weld appears to carry all the load from both members at that corner into the column. Is that acceptable to you? If not, then you should probably look into doing something like your Option A weld
Dave

Thaidavid

 

[Heldbaum]

I would notch the column and weld knife plates at both sides

 

[Tmoose]

Is this a work bench, a mezzanine to support a 75 HP fan, or ??

 

[weab]

Like Thai says, option B takes double loads, but I'd say so does option A. That one weld should be analyzed to do double duty.

I think the load in option B still goes where you think it does. I generally prefer the more direct load path of option A. I don't like welding on top of another weld but I'd make an exception here. But I'm ok with either choice.

In this case I'd call for a flat profile for the first weld in either option. If fatigue is an issue, grind your weld(s).

 

[dozer]

Thanks for the responses thus far. Weab, I didn't really notice that option A gets double loads but your right. This goes to show that size on size HSS connection is kind of a pain. As far as what it is. Essentially it's a 3D truss. This is a cross section of the chord where to web members that are perpendicular to each other frame into the chord at right angles. It could see a variety of loadings ranging from say about 25% of the web members capacity to full capacity.

Oh, you know what I just realized? You would need to do something like fig. 8-19 from the AISC 14th ed. to make those flare-bevel welds. I think if you used the weld build out that they are showing, you would get a continuous load path in that inside corner in both direction (vertical and horizontal).

As far as the knife plates, maybe you've got something else in mind, but what I'm thinking would interfere with each other. Besides, I'm trying to keep the cost low. I would think that would be a more expensive option.

I think option B would be OK for relatively low loads. Have any of you ever actually detailed this type of joint?