Flare bevel weld on HSS column to HSS spacer

[structdtl]

I am designing the weld between the face of an HSS7x7x0.5 tube column and a HSS8x3x0.5 tube that is acting as a spacer. The weld is a pre-qualified flare bevel as the spacer is wider than the tube column. I determined the effective weld throat when filled flush, using with table 8-2 and table J2-2 of AISC 14th ed.
Because of the configuration of the frame supported by the HSS7x7, I have forces Fx, Fy and Fz as well as Mx, My, Mz acting on my weld group.
I have calculated shear and tension stresses on the weld due to each of the above-mentioned forces and moments. My question is, can I use the formula below to determine if weld is ok?

(shear stress weld/shear strength weld) + (tension stress weld/tensile strength weld) must be less than 1

I have not completed design checks on the HSS yet, as I am making my way through the design.
Any input is appreciated
Thank you,

 

[JAE]

A sketch might be helpful

 

[structdtl]

just uploaded

 

[Lomarandil]

Yes, considering that interaction at any given point in the weld perimeter (or conservatively considering that interaction for the peak demands combined) is appropriate.

----
just call me Lo.

 

[structdtl]

Thank you Lomarandil.

Another question:
Is there a reason why the capacity for a flare bevel weld in tension can not be increased by 50% like you would a fillet weld under the same conditions? I am looking at table J2.5 of the manual

 

[r13]

In general, a "spacer" is to separate two elements, and is considered a non-structural element, as it usually does not share, or carry load. Your sketch shows the HSS8x is only affixed to the column, so why call it a spacer, and where is the design force came from? Just curios.

 

[structdtl]

retired13:

The HSS8x3 will be welded to the wall of a tank. It is an structural element I am designing as well. I was wrongly calling it a spacer. The HSS8x3 not only gave me the 3 inches I needed to clear the top of the wall but it works better than a plate for the given loads. The HSS7x7 is part of a small rack for pipe at the top of a tank

 

[r13]

Glad you understand my confusion of the word. It was the case I've guessed, just wasn't certain about it.

 

[Lomarandil]

Is there a reason why the capacity for a flare bevel weld in tension can not be increased by 50% like you would a fillet weld under the same conditions? I am looking at table J2.5 of the manual

I suspect (but have no evidence) that the throat geometry of a flare bevel weld affects this in some way.

AISI for cold formed steel allows a higher strength when flare bevels are loaded perpendicular to the weld, but not 50% -- closer to 20%, I think.

----
just call me Lo.

 

[r13]

This thread may help. Link

I don't know where is the increase, or restriction, came from. Look at table J5, for both welds, the nominal weld strength is the same as the yield strength of the base metal, with the resistance factor 0.9. Am I missing something?

 

[structdtl]

retired13 - thank you for the link, I had already come across it in my earlier research about fillet welds.

I wonder if the same applies for flare bevel welds. I also wonder if the provisions for leg size-to-length ratio for end-loaded fillet welds are also applicable to flare bevel welds.

 

[structdtl]

Lomarandil - Thanks for the reference. I am searching for AISI standard.

 

[r13]

The linked paper (steelwise) has excellent discussion on the 50% increase, and things you care about, please read on. Link

 

[structdtl]

retired13
Great find - Thank you!

 

[r13]

structdtl,

You are welcome. Glad to be helpful.