skewed fillet weld

By ssbn727 (*****)

Date 03-11-2010 01:13

Hi tbigtdav!

Can you by any chance post a picture of the drwing with the welding symbol included as an attachment here??? ;) It would help a bunch if we could see what it really looks like and how it relates to the joint in question. ;)

Respectfully,
Henry

By 803056

Date 03-11-2010 16:15

If you are working to a recent edition of D1.1, there is no such animal as a skewed fillet weld. There are specific requirements in D1.1 regarding how the design engineer specifies the weld (based on the throat) size and how the fabricator specifies the size on the drawing (based on leg dimension).

A fillet weld is sized based on the throat dimension where there is fusion to the joint root, i.e., the corner. That may not be the case with a skewed joint. The prequalified joint details assume fusion does not extend to the joint root and provide a Z-factor that has to be considered when sizing the weld. Since the design engineer may not be cognizant of who the fabricator will be or what welding process is to be used, it is left to the fabricator to specifiy the weld size for the welder with due consideration for the welding position, dihedral angle (of the skew), and welding process.

Best regards - Al

By supermoto (***)

Date 03-15-2010 13:55

What about if there is no open "groove" that needs to be filled and the plate was cut to sit flush on the other member. Then would you not have a skewed T-Fillet weld? We have a lot of both and whether or not the detailer is right is is ususally detailed as the acute side having a like a 5/16 and the obtuse side having a 3/8 fillet weld. Then you would have a skewed fillet weld.

How would you determine how much weld is required? Just fill the groove up so the weld continues on the same slope as the detail/welded member?

I understand there are prequalified T-Joints that give you restrictions on 3.11

By 803056

Date 03-15-2010 14:40

If you read the section on skewed joints you will note they do not refer to "fillet welds.” Fillet welds are defined as being applicable to joints where the dihedral angle falls within the range of 80 degrees and 100 degrees. Welds between members where the dihedral angle is less than 80 or more than 100 are not referred to as being fillet welds. There are specific requirements that have to be considered, such as the Z-loss in the root of the joint.

The fact that many detailers do not keep up with the applicable requirements or changes in the code do not make them correct. The CWI's task is made more complicated because one of his many tasks is to ensure the requirements of the applicable welding code, building code, etc. are met. The EOR can over-ride the CWI's call, but it should be in writing once the nonconformity has been reported (in writing).

There is nothing wrong with a sharp CWI pointing out inconsistencies or errors on an approved drawing. Once the Engineer of Record responds in writing to the errors or omissions it is his responsibility (it always was and still is) to verify the structure is suitable for the intended purpose. Most competent engineers will address the concerns if they are properly presented in a manner that is clear and concise. I refer to the appropriate code clause in my report and I include a sketch or photograph where it will clarify the situation.

The last thing most engineers want is to be involved with a failure where a potential problem was identified beforehand. Remember, a failure does not necessarily mean the structure collapsed.

Best regards - Al

By supermoto (***)

Date 03-15-2010 15:38

What about in annex B range of dihedral angles between 60 and 135, assuming no root opening 1/16 but not to exceed 3/16 if it does than to add directly to leg size, per D1.1 2008.

Not sure where it refers to skewed joints to not be referred as a fillet welds.

By 803056

Date 03-16-2010 00:43

I am looking at AWS D1.1-2006 because it is the one I have in my computer. There are few differences between the 2006 and 2008 editions with respect to groove welds, fillet welds, and skewed joints in Clause 2. Groove welds are addressed in clause 2.3.1, fillet welds are addressed in clause 2.3.2, and skewed joints in clause 2.3.3. Separate clauses, each covering different weld types. There is no mention of “fillet welds” in the clause on skewed t-joints. They talk about prequalified skewed T-joints with a reference to Figure 3.11, but they don’t talk about fillet welds in skewed T-joint in clause 2.3.3.1.

They talk about how the engineer is to specify the weld in a skewed T-joint and how the fabricator is to specify the weld size in a skewed T-joint in clause 2.3.3.2. There is no mention of fillet welds in that clause.

Likewise in the clauses that follow in clause 2.3.3, there is no mention of fillet welds. There is no mention of fillet welds until you get to clause 2.3.4 where fillet welds in holes and slots are addressed.

The size of the weld in a skewed T-joint is defined, as is the length. If the welds were considered to be “fillet welds” there would be no need to redefine them in clause 2.3.3, they were already defined (for a fillet weld in clause 2.3.2.

Older editions of D1.1 used to talk about fillet welds in skewed T-joints, but that terminology has fallen out of favor for several years.

I have included an excerpt from D1.1-2006. Where is the term “fillet weld” used in clause 2.3.3 Skewed T-joints?

I hope this helps to claify some of the confusion.

Best regards - Al

SkewedT-JointsClause2-3-315March2010.jpg (168k)

By eekpod

Date 03-16-2010 10:51

tbigtdav
It sounds as if the detailer/ engineer took into account the fact that when the plate was tilted over and created a gap on one side, that he accounted for this gap in the weld size on the drawing. At least that's my intrepretation.
If the plate were square off the main member at 90 degrees and let's say it called for a 5/16" fillet weld on both sides, as the plate was tilted/ leaned over to create the "skew" this would result in a gap on the open side. The detailer would add the size of that gap to the original size of the fillet weld and that's how they ended up with the bigger weld on the open side.
At least that's my opinion. Chris

By jwright650 (*****)

Date 03-22-2010 18:35 Edited 03-22-2010 18:38

Chris,
The AISC 13th edition of the Construction Manual addresses this condition(skewed shear tabs in the webs of beams)....several ways to approach the weld call out depending on the situation.

See AISC manual Table 10-13, pages 10-164(for 5/16" and 3/8" thick plate) and 10-165(1/2" plate)
Also see Figure 10-38 on page 10-151

note the skewed connections and that they use a fillet weld symbol on all but one, and they call it out as a BTC-P4 modified. Also note that some use the square edge of the skewed plate and others use a prepared edge on the skewed plate; where the plate meets the web.