Weld Group With Different Sized Welds

[Delmarva_Struct]

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!

 

[XR250]

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.

 

[Delmarva_Struct]

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.

 

[canwesteng]

Elastic analysis and consider the weld group to fail when the first weld does, which could be the 3/16" weld in your case.

 

[Delmarva_Struct]

Canwesteng..Can u give me a reference or a worked out example?

 

[Delmarva_Struct]

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?

 

[DrZoidberWoop]

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.

 

[canwesteng]

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.

 

[jhnblgr]

Wouldn’t you use the moment of inertia of the weld as a line?

 

[Delmarva_Struct]

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.

​

 

[JAE]

I believe you always have something to contribute. Your posts with questions show you've definitely got the smarts to join in with help.

 

[BridgeSmith]

Seems you may need an additional plate on the inside of the flange.