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Weld Group With Different Sized Welds

Delmarva_Struct

Structural
Aug 23, 2022
36
I have a 2" plate that is sitting on (2) W10x15 beams. The plate is welded ( by the contractor) to the flanges of the W10x15 with a rectangular line weld 3/8" all around. Considering that the thickness of the W10x15 flange is 0.27", my understanding is that on one side the weld can be no more than 0.27"-1/16" = 3/16". So now i have 3/8" welds on three sides but just a 3/16" on one (longer) side of the rectangle. How do i analyze this weld group? I know how to do it when all the welds are the same size but not when there is a variation in weld sizes.

Pdf drawing is attached!
 

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You could ignore the 3/16" welds. What is the demand? Depending on the magnitude it may not even be close to being an issue.
 
This is for a elevator brakes welding and force is 9500lbf. Since the force is applied eccentrically there will be moments acting on the welds too.

I require a FOS of 5! I did try 3 sides only and was only able to get a FOS of 2.31.
 
Elastic analysis and consider the weld group to fail when the first weld does, which could be the 3/16" weld in your case.
 
Canwesteng..Can u give me a reference or a worked out example?
 
If i use line welds and calculate section properties and compute the lbf/in, then i am doing this assuming the stress is equally distributed to all the weld lines. With different sized welds, will the stress be equally distributed to all welds? or will there be a variance in stress distribution based on stiffness or size of welds?
 
This is for a elevator brakes welding and force is 9500lbf. Since the force is applied eccentrically there will be moments acting on the welds too.

I require a FOS of 5! I did try 3 sides only and was only able to get a FOS of 2.31.
Uhhhh. A lot of red flags... highly eccentric weld group and possible fatigue considerations. Also, a 2" flat plate is acting as your "hoist/brake beam"....... Unless I'm missing something, I hope I never set foot in this building. Half a mind to report.
 
Assuming the welds are the same stiffness should be conservative, as the weaker welds will attract more load than they would otherwise. I suspect the actual force distribution is going to be a function of the connected parts and not the welds, so you could look at that as well.
 
Wouldn’t you use the moment of inertia of the weld as a line?
 

JAE

I understand.. My apologies!

I don't feel like i have the experience to contribute just yet. I will plan on doing that as i feel more comfortable.

 
I believe you always have something to contribute. Your posts with questions show you've definitely got the smarts to join in with help.
 
Seems you may need an additional plate on the inside of the flange.
 

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