Beam Web Opening Too Large

[carnahanad]

Some beam web openings were cut larger than what I had called out on plan for a project. The beams are W12x14; pretty small. The current size violates the detailing and geometric requirements of the design guide so I need to "fix" the beam.

I’m looking for a little guidance on what to do:
1. First thought is to have them fab new beams with the correct size as they aren’t matching the construction documents.
2. Sandwich plates on either side to essentially add web back into the beam, a little worried about the force transfer and the discontinuous web.
3. Add a single plate, cut to required shape that would fill in the web. The web is only 3/16” so this wouldn’t be too much work.

Just curious if anyone else has run into this.

 

[rb1957]

FWIW ... if you do 2 you'll need to fill the void (well, i guess, i think you need to ...)

option 3 would have the right size cut-out in it, yes?, and you're relying on the weld to transfer the load into the filler piece. to me, depending on geometry (pic would be nice) this may be adequate; or you could combine 3 with 2 ... fill the void with a filler that haas the right cut-out in it, add doublers both sides to reinforce the weld.

another thought, possibly dumb, would frame the cut-out, add doublers above and below the cut-out on one side of the web, and vertical doublers left and right of the cut-out on the other ... clear as mud ?

another day in paradise, or is paradise one day closer ?

 

[KootK]

We've all dealt with this before unfortunately. How big is the hole? What is the magnitude of the shear? Is the hole cantered on the beam vertically? Is it a composite beam? Do you have space available below the beam? Where along the span is the hole? Any other nearby holes?

W12x14 is a pretty small beam. Depending on your situation and where construction is at, wholesale replacement might be the least costly alternative.

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.

 

[JAE]

Based on your Item 1 - since the beam isn't the correct size anyway why aren't you replacing it?

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[carnahanad]

To clear up a few things.

The beam size is the right size, but the hole is not.

There are actually two holes. Both detailed to be centered vertically, 5" tall x 12" wide, spaced evenly along a beam that is 16'-4" long. The beam is non composite with no point loads, just floor loading. The beam is non-composite due to in-floor heating piping putting voids in my concrete deck, but that's a different discussion!

The holes that are in my beam are in the correct spot, but 18" wide. I used RAMSbeam to do the design originally and 5"x12" was the max the software would allow me to get. I went to design guide 2 and went through the checklist and found that 5x12 is the largest I could do by the Table 4.5 requirements.

I'm leaning towards Option 3 the more I think about it and using a plate that is the same grade as the beam. They can add (2) 5" tall x 3" plates and full pen weld 3 sides. This allows the force to transfer as originally designed.

Thanks!

 

[BUGGAR]

How much do you charge the Contractor to fix his mistake? I usually do this cost plus with no time extensions included. The Contractor has to request a separate time extension and my lawyer says that this, as an extra to the Contract, carries additional charges to the Contractor.

 

[carnahanad]

The cost is something I'll let the Construction Manager figure out with the fabricator and mechanical contractor. I'll probably give them the choice between supplying a new beam with the correct beam web opening sizes or reinforcing with some kind of detail.