HSS to HSS Connection 4

[steelbeam]

Can someone help me with the design of a welded connection for a short stub beam to the main beam. This will be a moment connection since the short stub beam ( about 12" long) will support an equipment
hanger load. The main beam HSS 14 x 6 x

​

1/2" has been sized for torsion created by the cantilevered load. The tentative size of the stub beam is HSS 8 x 4 x 1/2". I would like to weld the two members in the field without connection angles.

Thank you for any help or direction you can provide.

 

[Structurecrg]

Assuming both members are oriented with their longer dimensions vertical, and the end of the HSS8x4 is away from the round edges of the beam, just use an all around fillet weld.. 1/4” or 5/16” should work, depending on the loads.

I recommend using Blodgett ‘Design of Welded Structures’ method of checking the weld group as a line if there are lateral loads & thus biaxial moments on the weld.

If only vertical loads on the HSS (no seismic), you could just resolve the moment into a force couple and check the top & bottom welds alone.

 

[CANPRO]

CIDECT Design manuals are an excellent reference for this. See link below. You can register and download all of the manuals for free.

http://www.cidect.com/en/Publications/

 

[steelbeam]

CANPRO, what reference manual would do you think will address my conditions, without downloading all of them. Thanks for the direction!

 

[BUGGAR]

I second Blodgett recommendation. Excellent resource for this.

 

[KootK]

As much as I love Blodget, I don't know that he covers the HSS wall failure modes. Nor the non-rigid base material weld stress distribution. I'd check but I'm on the road. Quick and dirty:

1) Deliver your shear in short weld segments near the centroid of the cantilevered member.

2) Split your monent up into a couple of line loads at the flanges.

3) Flexurally design a vertical strip of girder HSS wall for the line loads just described assuming the strip to be pin ended.

That should take you 10 min and will work for modest loads. If it doesn't work, move on to something more sophisticated.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[oldrunner]

If I remember correctly, AWS 1.1 has a chapter on HSS to HSS connections. We did a lot of various configurations - but this was about 25 years ago. Very good illustrative explanations.

Rectangular to rectangular connections as well as round tubes to round tubes.

 

[BAretired]

If the moment is very large, you may exceed the moment capacity of the wall of the HSS 14x6x1/2 in which case you will need to reinforce it.

BA

 

[Shu Jiang PEng SE]

Suggest to read section "K3 HSS to HSS moment connection" in AISC 360. There may be more items needing to be checked beside the the weld, such as the supporting HSS side wall plastification (the height of the branch to chord 8/14=0.6<0.85). You also need to check the torsion capacity of the supporting HSS and its connections to its supporting members.