existing footing assumed without reinforcing

huangyhg

existing footing assumed without reinforcing
if i assumed the existing footing without reinforcing steel, how can i determine the load capacity of the inverted 鈥?t 鈥?4+8+4" concrete footing which will support second floor and the roof?  
what is the thickness? (assuming 20" width)
dick
use the design provisions of aci 318, chapter 22 for plain concrete.
it just like a regular footing with 8" stem wall and the bottom is about 4"+8"+4".  the hight of the stem wall is about 24"
ken,
concretemasonry asked you for the thickness (depth) of the footing.  i take it your footing is 16" wide.  if it is at least say 8" thick, the capacity will depend on the soil strength.  do you know that?
oh! the depth is 9"
my error on the quick width calculation. i said 20" out of habit and meant 16" total footing width.
with a thickness of 9" and only a 4" projection beyond the wall, there is no bending or shear problems in the 4" wide by 9" thick extension.
the capacity will be limited by the soil capacity.
dick