Common strip footing

[n3jc]

Greetings, I would like to hear some thoughts about following situation:

Structure (1) is a residental building (masonry walls with RC slabs), structure (2) is a canopy (RC frame + walls with RC slab on top). Structure (1) and (2) are not connected (dilatation is 50 mm) but since they are so close together we are dealing with a common strip footing. Because of the slope terrain we also have stepped foundations.

When designing a common strip foundation I have to consider that residental structure (1) will be build first and canopy later.
Since I am dealing with a slope terrain that means that 2 of the canopy's columns will be longer (4,50 m) than other two (3,00 m). They will be partially covered with soil which mean there will be some horizontal soil pressures acting on face of the columns (case A) and subsequently on foundation. I am not a fan of this option since two of my columns are relatively long.

I was thinking to design RC wall above stepped strip foundation so all 4 columns would be the same height (case B). But that way I am dealing with larger soil pressures acting on common foundation (since RC wall has larger face area than RC column). So I think that idea is not that great. What do you think?

How would you design this common foundation? I also want it to be as simple as possible for the contractor to make. I dont want to overthink/overcomplicate things. Your opinion will be appreciated. Sorry for poor language.

CANOPY:

 

[KootK]

1) I don't think that the soil load on your columns would have a great impact on their design so I'd be inclined to do whatever would be easiest for your contractor.

2) A simple solution that would be common in my area would be to cast a stem wall over the footings that was common to both the columns and the CMU wall.

 

[n3jc]

Thank you for reply KootK.

I suggested a common stem wall but was denied - the issue is placement of hydro insulation.