Help. Need help with Footing in the wrong location 4

[Berniedog]

We are the EOR on an office building and we did the stair design also for local fabricator. We located the footing for the single column for the monumental stair. The stair was revised but we didn't catch the revised location for the single column. Well the Architect says we cannot cut the floor. We have a 3'x3' footing with a 4" concrete slab. The new post is 14 1/2" off of the centerline of the footing. Allowable bearing is 2500 psf.

So P/A = 1.53 psf
M/S =3.71
P/A +M/S = 5.24

 

[oldestguy]

Question of BA. Just how do you install a single pile under an existing column? Why only one?

 

[dik]

OG... that's why I was thinking of 2... not so much eccentricity.

Dik

 

[oldestguy]

dik: Working inside a building presents a bunch of challenges. Even the fixes proposed will be influenced significantly on which one might be best do to that restricted place. In our position, there likely are things we don't know that will control how this goes. A photo or two or plan cross section would help a lot. Maybe get the architect to come up with something besides restrictions.

 

[dik]

OG: no doubt... there are a couple of contractors in this neighbourhood that install micro piles from within. They have a little tripod rig that as long as there is a 3'x7' door, they can install them... not in a crawlspace, though.

Dik

 

[BAretired]

Question of BA. Just how do you install a single pile under an existing column? Why only one?

If the column is existing, you can't. I am hoping that the column and stair are not in place yet. Then one pile would be centered under the column prior to placing the column.



BA

 

[hokie66]

I saw nothing in berniedog's posts to indicate that the column was already there. So I think the single pile solution is the least intrusive option. But then, I vote for digging out the footing, casting a new larger footing, leaving enough room in the hole for the architect.

 

[Canuck65]

Changing the focus from footing level to the top of column level. Is there any way the column load can be picked up within the floor system above and supported by a transfer beam? One end of the transfer beam would be located above the centre of the existing footing, then the other end of the transfer beam could possibly be supported on the perimeter foundation wall. I don't know the layout of the staircase, so quite possibly this might be a conflict. Just trying to think outside the box.

 

[dik]

leaving enough room in the hole for the architect

another star... great comment... have to be careful with organic material and concrete <G>

Dik

 

[JStructsteel]

Maybe I am missing something, if the slab cannot be cut, then its in place. Thus the column must be bearing on top of the slab? Can the slab take the load, spread out over a bigger area?

 

[BAretired]

jrisebo,
Yes, the slab is in place. If the column has not been erected, it is not bearing on top of the slab. It seems unlikely that the slab could take the load unless it was designed to do so.

BA