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Welding Procedure/Weld type for Heavy W Truss

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Heldbaum

Civil/Environmental
Jan 27, 2017
128
Hello,
I am looking for help/recommendation on the welding procedure my client has asked me to provide. I do steel detailing and engineering for him. We are working on the project where 3 heavy trusses were designed. Top and bottom chords are W14x311 and diagonal are made of W12x152 and W14x120. Each truss is only 6'-6" deep therefore directly welded connections were chosen and designed. Flanges in all diagonals get CJP to top&bottom chord flange and webs are welded with fillet weld. The diagonal angle varies from 30 deg. to 55 deg. I discussed with my client (steel contractor) that they will bevel the flange on one side with 1/4" root opening, 1"x1/4" backing bar and full pen. IS there a pre-qualified procedure in AWS D1.1 for this type of joint ? I know there is TC-U4a-GF 0 a single bevel-groove weld for T-joint but I am not sure if this would apply here since diagonal to chord connection is not at 90 degrees..Or it should be one of CJP T-, Y-, K- Tubular Connections presented in Figure 3.6..
Any help is much appreciated. Attached is screenshot of one typical connection/node.
 
 https://files.engineering.com/getfile.aspx?folder=b00e2543-5d10-4684-b27d-3f7be474f7c7&file=Joint.jpg
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Note 10 in the prequalified tables states that the orientation of T joints can be between 45 and 90 degrees. Anything less than 45 degrees will need a WPS.
 
Consider checking AWS D1.1 under the heading of Design, then Welded Skewed T-Joints. The specific clause is dependent on whether you use AWS D1.1:2020 or D1.1:2015.

D1.1 considers the fillet weld to be appropriate for a T-joint when the dihedral angle between the members is 80 degrees or larger, but no more than 100 degrees. If the dihedral angle is less than 80 degrees, or more than 100 degrees the connection is simply a welded skewed T-joints. The weld is no long called a fillet weld. When the dihedral angle is less than 60 degrees, there is some assumed incomplete fusion at the root. The amount of incomplete fusion is given as Z-loss and is dependent on dihedral angle, welding process, and position. The Z-loss must be considered when the fabricator sizes the weld.

I've yet to see this properly accounted for when sizing the welds.

 
Have you considered turning all the members the other way? I have seen lots of trusses with heavy W14 members, chord and web, fabricated with the inside of the flanges planar.
 
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