HSS TO HSS KNEE CONNECTION WELDS 1

[reverbz]

Hey Guys,

When doing a HSS to HSS knee connection(with no plate), what welds do you typically use? Also, for an HSS sitting on an HSS does a fillet weld work? I've attached a sketch for both.

Thank you!

 

[Once20036]

In your top condition, considering the rolled corners of an HSS, you`d be using flare groove welds.

For your bottom condition, you`d have a fillet on the bottom, a butt weld (which is a non structural weld) on the sides. I`m not sure what I`d call the top.
I wouldn't expect much measurable/reliable capacity from this set up, and would suggest you get into beveling the edges and using a partial penetration weld instead.

 

[SethGuthrie]

AISC Design Guide 24 Hollow Structural Section Connections is a good thing to review. There is a whole chapter on weld recommendations. Fillet welds can often be used, but PJP and Flare-bevel welds come out cleaner.

 

[bugbus]

@Once20036, I'm confused about what you mean by the sides being non structural welds?

Agree that the unstiffened mitre joint is not ideal but it can be made to work in some situations. The usable capacity is something in order of 1/2 of the bending capacity of the hollow sections themselves. Adding a plate between can boost that up to 100% pretty easily.

 

[Once20036]

@bugbus - i`m not aware of any AISC/AWS standards for a butt weld, as you`d have between the sides.
My understanding is that there's no way to define/consistently measure the throat of the weld, and therefore, the strength can't be calculated.