Effective Throat of FIllet Welds in Skewed T-Joints?

[rocketeer1]

Question about the following: In the AWS D1.1 (2010), Annex B, Effective Throat of Fillet Welds in Skewed T-Joints:

Given: the skewed T-Joint angle is 120 degrees (psi symbol), zero root opening.

Required: strength equivalent to a 90 degree, 3/16 inch fillet weld.

Per the D1.1, the equivalent leg size would be 1.23 x 0.19 = 0.234= w.

In calculating tn in the D1.1 (tn defined as the distance from the root of the joint to the face of the diagrammatic weld) , tn = w/(2sin(psi/2))= 0.234/(2x0.866)=0.135 . I am assuming that tn is also the weld throat and that this is what would be used in calculating the stress in the weld - do you agree with this?

Also, in calling out the weld symbol on the drawing, would you call out both the leg size and throat of the weld? Maybe as follows: .234(.135) or rounding up the weld size: .25(.135) ? Or would you add an extra 1/8 inch to the throat for penetration or just forget about any penetration and be conservative?

Thanks for the help.
rocketeer1

 

[connectegr]

For acute angles less than 45* you are basically increasing the fillet weld size for the open space created by the angle. This can be done the gaps up the 3/16". This gap is dependent on your material thickness and the angle. A good example are the fillet welds shown for skewed single plate connection is the AISC 13th Ed Manual. The leg sizes of the fillet weld are equal, or rather the increase is not added to just one leg of the weld.

http://www.FerrellEngineering.com

 

[gtaw]

If you read D1.1-2010 carefully you will note that the weld is not called out as a fillet weld once the dihedral angle is less than 80 degrees or more than 100 degrees. One basic premise of a fillet weld is that there is fusion to the root. Once the dihedral angle is less than 60 degrees fusion to the root is not anticipated and the designer and the fabricator have to consider the Z-loss.

The design engineer is responsible for specifying the throat, while the fabricator's detailer is responsible to determine the appropriate leg dimensions, allowing for Z-loss, on the shop drawings. Since the weld is no longer a fillet weld, a fillet weld isn't appropriate. A sketch of the joint details indicating the leg dimensions required is a preferable approach.


Best regards - Al

 

[gtaw]

Correction:
If you read D1.1-2010 carefully you will note that the weld is not called out as a fillet weld once the dihedral angle is less than 80 degrees or more than 100 degrees. One basic premise of a fillet weld is that there is fusion to the root. Once the dihedral angle is less than 60 degrees fusion to the root is not anticipated and the designer and the fabricator have to consider the Z-loss.

The design engineer is responsible for specifying the throat, while the fabricator's detailer is responsible to determine the appropriate leg dimensions, allowing for Z-loss, on the shop drawings. Since the weld is no longer a fillet weld, a fillet weld symbol isn't appropriate. A sketch of the joint details indicating the leg dimensions required is a preferable approach.


Best regards - Al