What is this weld and does it have any capacity? 2

[marinaman]

I've got a project where I have some fairly long spanning joists over a gym. Some joists are supported by a stiffened plate seat that the joists sit on.

The joist manufacturer made his joist seat the exact same plan size as my stiffened plate joist seat. Since his seat is the same plan size as my stiffened plate seat, the erector went around the edges of the plate seat/joist seat and welded the edge where the two plates meet.

It looks as though he may have gotten at least a partial penetration weld in there....its does not appear to be just a surface fillet weld....but I"m not sure what this weld should even be considered, and, what the capacity of such a "line weld" would even be.

There is a testing service on site.

I am thinking of having the testing service review the weld and get feed back as to throat thickness of the weld and penetration depth of weld, then, if deep enough, possibly accepting the weld.....or, rejecting it, depending upon the returned data.

The uplift loads are small and the lateral shear load is small.

The joist seat angles are 1/2" thick and the stiffened plate seat is 3/4" thick.

Could this be considered a slot weld?.....and if so, would need to have a 1/2" throat thickness per AISC?

 

[Guest102023]

The weld would be valid only if it was executed based on the drawing AND is supported by a qualified WPS (and of course qualified welders). If I understand correctly it is two plates layered together and welded on edge. A X-section sketch with dimensions would be helpful here.

 

[marinaman]

Brimstoner,

That's correct. Its as if you took two plates, one 1/2" thick and one 3/4" thick, of the exact same plan size, laid one on top of the other, and then welded the edge.

I believe the only solution to be to have the joist manufacturer create a detail of trimming back the joist seat and then welding the joist down.

 

[Duwe6]

"Ask the welds". Pick a sample of your joists -- I'd go between 2% and 10% -- and cut them through the weld. Cut to be 'cold', bandsaw or hacksaw, cutting transverse to the run of the 'face' weld. Then polish the saw marks out with a grinder and a sanding disk, then acid etch them [muratic acid], 10-40% nitric, 10-40% hydrochloric, etc. They all work]. The weld penetration will be easy to see.

If they were 'stick' or 'flux-core welded - SMAW, FCAW - there should be adequate penetration. If they were 'mig' welded - GMAW - I'll bet a month's pay to a stale beer that the penetration will be too small for you to be confedent in the joint being able to transfer any uplift or side loads.

Don't cut all the sample joists at once. Go 1-at-a-time, because if one fails you should reject the entire batch. Reworking [uncut] joists is not very hard or expensive. Grind out the 'face' weld and knock the bearing plate loose. Install a new plate at least 1/2-inch wider than the joist, giving a 1/4-inch 'shelf' to place the attachment weld on. That attachment weld will 'heal' the spot on the joist that was ground into by the plate removal. Easy.

If it was my job, I wouldn't test/section the joists; I'd put a couple of certified welders, with fitters to grind for them, to work replacing the bearing plates.

 

[Guest102023]

A non-conformance followed by a retroactive procedure qualification is in order (at the least). You will also need to justify the new joint design from a design load POV; this type of joint will not offer much of an effective throat.

 

[Ron]

This is a "seal weld". It has insufficient profile to be considered a structural weld. As Duwe6 noted, if you have a penetrating weld process such as SMAW, it helps but that will also depend on the electrode used and the travel speed.

The joist should be lifted, the seat narrowed by 1/2 inch or so and an appropriate fillet weld applied.

 

[Guest102023]

There is no such thing as a 'non-structural' weld.

 

[racookpe1978]

Pardon my French, but why cut out the existing "edge" weld?

Is there no room on the two plates to join them with multiple drilled holes (using a mag-based drill like a Hougen or Milwaukee) and then bolt the two together?

 

[Ron]

brimstoner....OK....then it is a weld with insufficient profile and lack of pre-qualification in its configuration to meet typical welding code requirements and serve as an adequate structural weld.

 

[Guest102023]

Ron,
I meant that statement categorically.