Same width HSS beam-column connection at the corners 1

[SeizeTheMoment]

Hey all, I had a design where 8" width beams goes into a 8" width column. I did not think about this prior, but this would leave no access to a flare bevel on one of the beams with this design. Unfortunately the steel has already been fabricated otherwise I would have upsized the column. Has anyone ran into this before?

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

 

[GC_Hopi]

Groove weld? I have seen this arrangement fabricated but never ran a design. I would be curious on other's thoughts as well.

 

[bobbyboucher]

assuming you don't need to develop the full section strength at the connection, you can fillet at the corner of the the two beams. the first beam would be attached with flare bevel and the second beam would be fillet weld to the side of the first

 

[driftLimiter]

Can also use a penetration weld on the hss wall to get more throat width. PJP is recommended to avoid backer bar.

 

[dhengr]

SeizeTheMoment:
Measure the outside corner radius on your tubes, it should be about 3/8" +. Draw that joint to scale and see how it really looks and fits up. That leaves an 1/8" + gap at the root for a 1/4" wall thk., not the tight fit your sketch shows, so you probably do need some sort of a backer bar or rod. Do some reading and study on how flare bevel welds are made and how their weld throat is measured, they are not a CJP weld, nor are they a fillet. Also, their root area is usually pretty crappy in terms of weld fusion, penetration, accessibility, etc., you just can’t reach all the way into the root, so the throat dimension is usually discounted for this. The throat is measured from the flat face of the weld, into the sound weld metal near the root, less some code spec’ed. reduction. We used to tack the two members together, then use a compatible piece of welding wire, and lightly drive it into the root area with a flat nosed chisel to provide a sound/solid root area to weld on. Your detail is almost half right. Why not bevel the inside face of the N-S beam also? Then, you will have a legitimate groove to weld full. You run a small first pass to the root on each beam, and then fill the groove. That should give you a good quality weld on that inside corner. But, the throat &/or the weld area to the column, which may be smaller, is still shared by the shears on the two beams in your design.

 

[HTURKAK]

I would consider two options ,

Opt 1- Insert a square HSS sleeve to the top of the column with dimensions 9 in X 9 in having length 10 in. and fllet weld at the bottom edge all around and edge weld at the top

Opt 2- Bevel the beams all around 45 degr. then groove weld ..












Not to know is bad;
not to wish to know is worse.

NIGERIAN PROVERB

 

[KootK]

assuming you don't need to develop the full section strength at the connection, you can fillet at the corner of the the two beams.

My preferred solutions are shown below, aesthetics permitting. They are basically permutations of bobbyboucher's suggestion.

 

[milkshakelake]

An eccentric weld group with 3 sides (top, bottom, side) might be strong enough.

 

[Tomfh]

How hard is it working? Is getting complete penetration on that last side genuinely critical?

What’s the fabricator done so far?

 

[bugbus]

Could you do something like this? (Edit: just noticed this was already proposed by bobbyboucher)

As a side question, what's the general rule about welding on top of other welds?

 

[bugbus]

Or as an alternative to step 3 above, grind the edge of the second beam and do a single bevel weld so you can get more of a direct transfer of force through the beam web / column web.

 

[dhengr]

Bugbus:
Your’s is a really good picture of a good way to solve this welding problem. RE: your question..., “what's the general rule about welding on top of other welds?” Do you spec. multi-pass welds, is that welding over another weld? My understanding of the issue is that it is not a good idea to weld across, or weld into (generally perpendicular) an existing weld. This is because of the nasty triaxial stresses and nasty residual stresses set up when you do this. To add a few passes to a long existing weld I would likely do some preheating, just to relax the existing residual welding stresses a bit and prep. the materials for the new welds. Of course, you should always know the materials you are working on and their make-up before starting welding. Weld starts and stops in these regions are also problematic because of the potential stress raisers associated with them. Highly restrained joints are also problematic because of the high residual stresses they cause. The OP’ers. question and detail doesn’t really seem to have any of these added problems, except for the fact that flare bevel welds are really crappy structural welds because they are so difficult to do well. And, the terminations of those welds at the end direction changes are also difficult to do well without leaving stress raisers. I think that pressure vessel and pressure piping people have some code limitations on how close adjacent welds can be to each other and the issue of welding over other welds on a vessel or piping.