weld plates, I beam bearing.

[bb29510]

This is an issue I been fight with steel erectors for years. If the weld plate is not flat the beam wont set bearing on the plate. Some will have 100% on the weld and not the plate. This is the same with K joist. I like to see 100% bearing on beams and as much as possible with k joist. My question is, what does the structural engineer like to see on bearing?

master ICC inspector, AWS CWI

 

[Guastavino]

Not sure I completely understand your question, but I would say as long as they get the weld where I want it, and the gaps don't exceed those allowed by AWS for fillet welds, I likely would let it go. In the event of a large load, the seats/beams can deform some to bear. I mean, in an ideal world uniform bearing is the best, but I also have to be realistic.

 

[BAretired]

It is desirable to get bearing plates level but of course, they are never perfect. Even when the bearing plates are set level, the end of the beam rotates under load causing uneven pressure under the plate. When the end rotation of the beam is minimal, this is not much of a concern but if the end rotation is substantial, some engineers place a square bar over the bearing plate so that the length of bearing is short and central to the base plate. When this detail is used, the bar must be checked for bending and the beam must be checked for bearing stress in accordance with normal practice.

BA

 

[bb29510]

what about shim plates. some gaps are close to 3/8

master ICC inspector, AWS CWI

 

[BAretired]

A gap of 3/8" is too much. It is probably sufficient cause for rejection of the work.

BA

 

[KootK]

Once one considers natural camber, beam deflection, and realistic embed tolerance, the odds of having uniform bearing contact are pretty much nil.

In the world of precast, simply supported framing members rest on deformable bearing pads for just these reasons. And for serious loads, I'll do that too. I guess, for minor loads, there haven't been enough real world problems to warrant the extra attention.

I like to have a stiffener centred over the bearing plate if possible. I feel that it helps to steer the load to where I'm hoping it will end up. Of course, that still usually requires some considerable deformation in other parts of the joint.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[bb29510]

So if the bearing gap is over a 16th, I could use the argument that it violates the wps on root opening. I know the weld is suppose to be stronger than the metal welded, but would you want the whole column be supported on the weld itself. OK I can understand when the total load is applied that the gap will close, but then you got change of cracking the weld. Am I wrong?

master ICC inspector, AWS CWI

 

[KootK]

but would you want the whole column be supported on the weld itself.

Usually not. Is this a column rather than a beam? If so, the issue will be more critical. The connection may need to meet the finished to bear limitations of AISC.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[allimuthug]

If the weld plate is not flat , THe column is supported by the weld on the base plate. Hence all the compression load in the column acts as shear in the weld , IF moment and compression and shear acts together and if the weld has enough capacity then the weld doesn't fail .
Normally all structural engineers check weld for tension shear and moment only .
If the weld has same capacity of the beam or column then no problem in bearing . But however if the weld is welded both sides it has same thickness of the flange and web i believe.
If the thickness of weld is equal to plate thickness no need to worry.

 

[BAretired]

We started by talking about beam bearing. Now we are talking about column bearing. Which is it?

BA

 

[allimuthug]

sorry i misunderstood as column bearing ......

 

[BAretired]

Ordinarily, if we are talking about column bearing, the base plate is attached to the column and it bears on a bed of non-shrink grout. Mounting a column on a plate embedded in concrete would not be a common occurrence.

BA

 

[RPMG]

From what I understand, you have a beam/k-joist designed as s a bearing connection, but there is a gap of 3/8"! for whatever reason.

Your solution is "Shim as required".

The shim should be welded to the bearing plate or beam/k-joist. If the beam/k-joist and/or shim should be welded to the bearing plate and/or shim, then the fillet weld should have different weld legs (3/8"x5/8"?), but the weld throat should be as required per the design.

 

[gtaw]

The AWS structural welding code includes provisions for "bearing". You have to have a copy of the appropriate code to do the work. You can look in clause 5 to find the information you need to properly assess the situation. If the conditions of the code are not me, report the discrepancy, include the relevant dimensions, and let the Engineer make a determination regarding "accept it as built" or "corrective action required". When corrective action is required, the Engineer should specify what the corrective action is. The inspector should not dictate what must be done to correct the situation.

Best regards - Al