Steel Col to Concrete Column

[Boiler106]

I have a new multistory steel building sitting on top of a single story of new concrete building, which in turns sits over top of an existing 4 story concrete building.

The steel columns align with the concrete columns, below, and the anchor rods get tied to the new concrete columnn cage. The new concrete column cage gets mechanically spliced to the existing columns below.

We have received a survey after our drawings have gone out indicating that the existing column cages are out of alignment from the record drawings by as much as 2". Using round numbers, it appears that this would be 1" out of tolerance, as ACI 117-90 4.1 allows for 1", if we assume that the existing column cages are centered in the existing rectangular columns.

This seems to be an issue with aligning my steel column anchor rods up with the new concrete columns below, without changing gridlines this late in the ball game.

It would seem that if the columns are 2" out at the existing level, they could be 3" out at the new concrete level.

If anyone had some input, I would appreciate it. Trying to brainstorm some solutions at this point.

Thanks,
B106

 

[steellion]

Try keeping the steel columns at the gridlines and confirm the concrete columns work for the additional eccentricity. It should be relatively painless to move the anchor rods for steel gravity columns.

 

[TLHS]

Get them to make up the difference in the new concrete storey, if you're really worried about it. You can likely make up that sort of dimensional issue just in the way you do the splices. They won't end up an extra inch out in the wrong direction if you sit down and explain what you're trying to do. Standard allowable tolerances are for standard situations. If you've got something unusual you can always tell them something different as long as it's actually buildable in a reasonable fashion.

 

[TLHS]

Regardless, though, that existing storey where they cage is in the wrong place is eccentric, so do a check that the extra moments don't break the building.