Moment Frame Beam Crack

[SteelPE]

A building I designed is currently under construction. The building is a 3 story office building with moment frames resisting lateral forces in one direction. During UT testing of the moment connections it was noticed that a beam had a defect in one of the flanges (I call shenanigans on how the beam made it all the way through to the field). The defect is a slab bubble that has produced a crack in the flange of the beam. The crack is about 3” long and penetrates about 5/16” into the flange of the beam.

I have never been privileged to deal with such an issue. The beam is in place and the contractor and the fabricator want nothing to do with replacing the beam. I have offered the solution of having the mill certify that the defect is local and will not have an effect on the integrity of the beam (once it is repaired). The mill refuses to give such certification.

How often does a beam slip through the fabrication process and make it out to the field with such a crack? Also, am I being overly cautious in worrying about the integrity of the rest of the beam?

Hopefully the picture link works:

http://files.engineering.com/getfil...a-8c14-2eb6fab28e7e&file=2018030995125118.jpg

 

[JAE]

Is this in a significant seismic category?

If not, then you could perhaps review the connection and see if the non-cracked area of the weld is still adequate.
If seismic, then I'd question if any repair would work without a risk of a stress raising inherent flaw in the weld or weld vicinity.

The contractor is contractually obligated to provide a "good" beam so in some sense it doesn't matter if "they want nothing to do with replacing the beam."



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[SteelPE]

The building was designed utilizing a R=3 system and is not in a high seismic area (Ss=0.22 S1=0.066)

My proposed fix is to have the erector cut the bottom flange free from the column and provide a 1/2" gap from the bottom flange of the beam to the columns (the damage is to the bottom flange). I was then going to weld a cover plate on the bottom flange on the beam and then CJP weld that new plate to the column. The weld of the cover plate to the beam wouldn't start until beyond the flaw effectively "skipping" the flaw in the bottom flange.

My concern isn't necessarily the repair, but rather what are the chances this beam contains more similar flaws that we can not see?

 

[JAE]

I don't have a working knowledge of how a flaw like this could be "systemic" through other portions of the shape.
You might try contacting AISC.

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[JoshPlumSE]

Any chance you could weld a haunch onto the bottom of the beam to provide the capacity. It should dramatically reduce the demand on the flange. You could even have them grind off this flawed weld after.

 

[dik]

Check to see if it influences strength... if not, then cosmetically and structurally repair... have the contractor provide his own engineering assessment. Else, have it replaced 'for reason'. Do not accept a credit for acceptance.

Dik

 

[Ron]

Have the area around the crack checked for delamination or other rolling flaws. If none are found, the crack can be arc gouged and welded to repair. Document the repair procedure.

Also, it appears there is a lack of fusion in the weld at the top right. Could be just a photo anomaly, but check it. Lots of "ditty balls" on the weld. A bit sloppy.

This is a fairly prominent weld on a thick member. Were pre- and post-weld heats required and followed?

 

[darthsoilsguy2]

photos are weird for estimating 'sizing'. But.... this weld looks big to me. i'd go through the effort of determining if the weld procedure fit-up was followed. looks like a big root opening. Big welds equal big Heat-Affected-Zones. If you are able to determine a weld procedure discrepancy that could help reduce the milling concerns and help identify more targets to investigate further.