Max Shims under Steel Beam Bearing Plate

[MyCupboard]

My question: Is there a guideline for how tall you can shim under a W-shape beam bearing plate? Is 4" out of the question? Would I need to consider additional analysis?

My context: I'm in the residential realm, working on a high end house that has various steel beams bearing on a foundation wall. These were utilized/designed for gravity only. The contractor for some reason wanted to provide a 4x6 sill plate instead of the 2x6 sill plate that we specified and detailed. They claimed it was a "stronger finished product". (I'll hypothetically concede that a 4x6 is a stronger finished product than a 2x6, but is that a common issue - 2x6 sill plates not being "strong enough" if it's been designed adequately for compression perp to grain?)

Because of the 4x6 (and i'm assuming other variations which i'm awaiting for clarification on) some of the steel beams reportedly require as much as 4" of shimming. They also asked if they need to change the embedment of the anchor bolt (no-but they do need to change the length) or need to make up the difference in height with non-shrink grout (instead of shims?)

My first thought is that as long as the beam is fully supported over the bearing area, then shims of 4" tall would be ok as long as they are welded together. But my worry is, taking it to an extreme, I wouldn't be okay with 48" of shims for fear of instability - so where is the line? is there a specific calc that solves this?

thanks all for your help!

 

[MyCupboard]

i'll add that the reactions that i'm dealing with are in the ballpark of 20.0k

 

[EngDM]

My question: Is there a guideline for how tall you can shim under a W-shape beam bearing plate? Is 4" out of the question? Would I need to consider additional analysis?

My context: I'm in the residential realm, working on a high end house that has various steel beams bearing on a foundation wall. These were utilized/designed for gravity only. The contractor for some reason wanted to provide a 4x6 sill plate instead of the 2x6 sill plate that we specified and detailed. They claimed it was a "stronger finished product". (I'll hypothetically concede that a 4x6 is a stronger finished product than a 2x6, but is that a common issue - 2x6 sill plates not being "strong enough" if it's been designed adequately for compression perp to grain?)

Because of the 4x6 (and i'm assuming other variations which i'm awaiting for clarification on) some of the steel beams reportedly require as much as 4" of shimming. They also asked if they need to change the embedment of the anchor bolt (no-but they do need to change the length) or need to make up the difference in height with non-shrink grout (instead of shims?)

My first thought is that as long as the beam is fully supported over the bearing area, then shims of 4" tall would be ok as long as they are welded together. But my worry is, taking it to an extreme, I wouldn't be okay with 48" of shims for fear of instability - so where is the line? is there a specific calc that solves this?

thanks all for your help!

Could the contractor not just keep the beam down at plate elevation, and add nailers to the top of the beam instead of shimming the underside?

 

[MyCupboard]

Could the contractor not just keep the beam down at plate elevation, and add nailers to the top of the beam instead of shimming the underside?

That's a decent idea, however some of the beams are supported on the opposite side by a steel HSS column which is already fabricated at the original height to support the beam in it's designed elevation. You'd think if they were going to take it upon themselves to change the design, they would think a half step ahead and make sure the other items weren't impacted - but...contractors.

 

[XR250]

I had this issue in a house I built. I used a piece of flatwise tube steel for the shim.

 

[ChipB]

I'm not picturing it in my head, but....
I work in the heavy industrial section and it's not too uncommon to provide a grout bed in excess of 3" for leveling equipment and what not.
Grout it with a high quality, non-shrink grout. I typically specify Five Star grout.

 

[canwesteng]

If no lateral load on the support and the beam is rotationally supported from framing elements at the level of the beam, there is nothing to really check. At some point a stack of shims under a stiffened beam might not provide enough rotational stability, though I would think that's taller than 4"

 

[MyCupboard]

excellent! thank you everyone for the help.