Hi Calculor:
How about the overall situation ... if there was mistake in the formwork,
did the wall get thickened inwards from the 4th floor to the 7th floor,
with the 5" of wall section being chipped off from the inside, how much of the wall thickness you have available?,
how about the reinforcing in the remaining wall section?,
would the wall section after chipping off the required amount, and the reinforcing in the wall, do you have enough of a wall section available structurally?
with chipping off the needed amount of concrete what does your profile of the wall look like both vertically and horizontally ... would it work without additional reinforcing with structural steel?,
then even if the wall with concrete chipped off needs some reinfocing, what would be practical ... should it be the additional columns as you have thought about, or should it be something else,
well, you get the idea where I am coming from ... you need to put all the cards on the table and see what is the best approach under the circumstances.
Yogi Anand, D.Eng, P.E.
Energy Efficient Building Network LLC
ANAND Enterprises LLC