Fabricator machined a spotface into weld of fatigue loaded area [pic]

[mecheng24]

Hi,

I have a fabricator who was off on the placement of his holes and now needs to machine away part of a weld.

In the picture attached, the spot face needs to me machined even more than shown to make room for the washer so we will have an intermittent fillet weld at that point. I know stitch welds are to be avoided in fatigue situations but is this basically no different than a stitch weld?

Can I just analyze this point in the weld using detail 3.4 of Table A-3.1 of the AISC 360 (stress category E)?

Thanks in advance
J

 

[TehMightyEngineer]

I'd say you could probably look as this being a stitch weld for fatigue issues. It might perform even better than documented as the welding was never terminated so you wont have any built-in stress risers due to weld end shrinkage.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[mecheng24]

Thanks for the reply, so scenario 3.4 of App3 in AISC 360 (attached) sounds like how I want to analyze this.

 

[dhengr]

Jgrady:
What kind of a joint is this? What are the loads? How close to the hole is the toe of the weld? Is the bolt highly tensioned? You might consider minimal grinding of the fillet toe, nicely faired in at the ends, clipping a washer to fit the toe, and then putting a second washer over the clipped washer, and letting it go at that. How many places does this occur, and what are the actual fatigue conditions? Many more questions than answers, but you do leave a pretty sharp reentrant corner/notch when you grind/machine part of that weld away and that may be worse than leaving it alone. You’ll machine right to the web, and still have to clip the washer. What’s the best fix, maybe not the easiest, or maybe it is the simplest.

 

[racookpe1978]

Yes, I'd rather trim the washer than cut the fillet weld. The nut/bolt can probably be turned 15 degrees to increase clearance, and the washer can be cut down to get a mating surface on the its bottom with the fillet weld and flat structural steel.

Be sure it does "kiss" the structural steel for as far as possible though. A few minutes with a grinder will do it.

 

[Ron]

Agree with dhengr and racookepe1978....clip the washer (assuming the bolt hole itself does not impinge on the fillet weld)