Footing Jacketing

[FaisalAAOUATIF]

Good Evening / Morning .
Due to a additionnal load on an existing isolated footing , i'm trying to redesign it by using the jacketing it by two orthogonal beams.
My question is about new beams reinforcement ( please see attachment ) :

1.Is longitudinal beams reinforcement , by direction , should balance all the new effort from the column , regardless existing reinforcement in the existing footing ?
2. What are disposition for calculating lniks between old and new concrete ?

Thanks a LOT.

 

[RPMG]

I haven't seen a perimeter beam around a footing like that.

At the pier above the footing, I recommend adding a shear head made out of channel steel, and reinforcing similar to a post at a two-way slab (inverted). Design the footings for the factored soil capacity, not the applied load, as a courtesy to future engineers.

 

[WARose]

I've done something similar myself for additional load on a footing. However, what I did was to widen the footing to handle the new pressure....and have 4 beams (2 per direction) on top of the footing. The new beams ran on top of the old & new parts of the footing. The whole thing looked like an inverted double T beam. The beams on top of the footing tied directly to the pier delivering the axial load. (So the distance between the beams was the width of the pier.)

I tied it all together with re-bar and Hiltis. (The required number of which depended on shear flow, etc.)

Doing this made the footing rigid enough to ensure any additional load was evenly distributed (I hope).