Shoring Column for Footer Reinforcement

[OUOY]

Hey everyone,

We have a pretty odd situation coming up and wanted to get a few ideas of how to go about it.

We're excavating under an existing column and footer to reinforce it so it take the new loads of the renovations.

Columns have a 290k DL and 80k LL but we're able to take the LL out and prohibit any work on the above floors. The floor above is a one way concrete joist system.

Also planning on doing 1 column at a time to make it a lot easier for everyone involved.

Attached are the details and one of the columns we'll be doing the work on, the wall on the right is to be demolished as well.

The biggest issue we have is how to approach it and support the column properly. Is the best way to go about this to simply shore the beams running into the column as shown and support the joists running out as well? We're fairly uncertain of whether we need to actually attach to the column and support it due to the loads from the upper floors or if shoring the beams would be sufficient.

 

[jayrod12]

Generally speaking where I've had multiple floors of load to shore up, we've provided shoring posts at each level to take all of the load off the column. Then the column will essentially hang off of the shored beams while you do the reinforcement procedure.

 

[OUOY]

Generally speaking where I've had multiple floors of load to shore up, we've provided shoring posts at each level to take all of the load off the column. Then the column will essentially hang off of the shored beams while you do the reinforcement procedure.

That's what I was thinking rather than trying to support the entire column at the bottom of it all or underpin the footer to support it with helicals. I'm guessing you just go X feet off of the column and catch the beam in the same spot the entire way down?

 

[jayrod12]

That's correct. With the number, or capacity of the posts increasing as it goes down. For this type of shoring, sealed shoring plans designed by an engineer would be a requirement where I practice.

 

[OUOY]

Oh absolutely, just trying to get an idea of how to tackle it since the original plan since we bid it has changed quite a bit. Thanks for the help!

 

[EireChch]

DIK not going to be happy, eh Bridgesmith!!

OUOY/Jayrod - are you essentially talking about just propping the beams connecting to the columns, say 12ft away or so. I think thats what you mean but wanted to be sure.

OUOY - helicals / micropiles could be an option too, but may not be since its somewhat easier to get a contractor in to install props and do some excavation beneath the existing column.

Having to engage a new contractor just for micropiles will be expense give the minor amount required. Mobilisation will be more than the 6 micropiles or so required.

 

[jayrod12]

12 feet is pretty far. I was thinking more like barely outside the existing footing area.

Someone would need to run the numbers on the beam and see how far it could span.

 

[Ron]

Two comments:
1. Agree with jayrod's approach.
2. Ouoy.....it is a footing, not a footer!