Hi,
I am designing an isolated footing based on ACI318-14 using the attached file below (please refer to "Finalized" job). I noticed that SFA has a different method in calculating for flexure compared to the conventional method. Instead of taking the moment at the nearest column face, it takes the moment at the other face of the column (see image). For instance, for a 1.050 x 1.050 m footing with 0.3x0.3m column, the critical section for the flexure would be (1.050 /2) - (0.3/2) = 375mm. However, SFA's critical section is 675mm. Can somebody explain why SFA has a different method?
[CE 196] - Redesigned Isolated.sfa
The footing bends like a cantilever on both sides of the column. If the column transfers moments to the footing, or if it is eccentrically positioned, those moments will be unequal. The program designs for the larger of those moments.