Flare Bevel Groove Weld Detailing 1

[jreit]

I am welding a single angle cantilevered post to a HSS member.
The angle is a L4x4x1/2 and the HSS is a square 4x4x3/8.

The weld strength is not really an issue.
The moment demand is about 80 kip-in.
My weld section modulus is (4 x 4)/6 x 2 = 5.33
Weld Force = 80/5.33 = 15 kips/in required
Effective thickness 5/16" groove weld - using ASD - my capacity is (0.6 x 70)/1.88 x 5/16 x 4 = 28 kips/in
I have a safety factor of ~2.

My concern is the detail - is a groove weld the full length of the HSS member a substandard detail?
Could a crack form and propagate at the root?

 

[IceNine]

You might want to double check your capacity calculation. Why are you multiplying by 4 to calculate the k/in capacity?

 

[Lomarandil]

I wouldn't be concerned if the weld is detailed to be the length of the HSS flat. I don't think it's ideal to use the full HSS depth as you've shown (even if that's what the welder does in practice with some pseudo end-terminations top and bottom).

 

[IceNine]

Also, welding to the face of the tube wouldn't be a flare-bevel weld.

 

[jreit]

@IceNine Thanks good catch that's right I need to update the orientation weld group.
The new weld group has a section modulus of (4 x 4/2) x 2 = 16
Weld Demand Force = 5 kips/in
Weld Capacity = 7 kips/in

@Lomarandil - that was my first option but the HSS4x4 has a workable flat of ~2.25". Limits the length of weld to below what's needed for design.
I could specify a weld return on the vertical face. Provides a better quality end termination.

 

[ProgrammingPE]

How did you come up with an effective throat of 5/16"?

In accordance with Table J2.2 (Effective Throat of Flare Groove Welds) per AISC 360-16, R = 2*t for HSS and Effective Throat = 5/16*R for Flare Bevel Groove Welds (SMAW, FCAW-S, SAW).

R = 2*t = 2*3/8" = 3/4"
Effective Throat = 5/16*(3/4") = 0.23"


STRUCTURAL CENTRAL:
Weld Strength Software
Weld Strength Video

 

[jreit]

Agreed, but the GMAW welding process allows a 5/16" effective weld throat to be achieved for a HSS with this radius.

5/8*0.75 = 0.47"