Using the swimming pool foundation to support concrete columns loads 1

[Gus14]

I am thinking about using the swimming pool foundation to support two concrete column each one of them load is 750 KN. How is it possible to include the effect of the 750 KN load in foundation design ?. I attached a sketch

 

[Ron]

Swimming pools are rarely constructed with the same structural care as distinct foundations. Further, the pool foundation was not designed for a high concentrated load such as your columns. I would say "NO".

 

[Gus14]

Yeah, I know that's why I will be designing the swimming pool foundation. I didn't know how to start. So I found the soil reaction from the swimming pool wall (2-meter wall ) alone (without the columns loads ) and it was about 30 KPA. Then I modeled the foundation with the load of the column alone using safe ( Don't know how to draw a retaining wall in SAFE software ) the soil reaction was 160 KPA. So basically the total soil reaction would be around 200 KPA which is okay. However, what surprised me is the 1 cm difference in settlement predicted by safe between the side of the columns and the opposite side, but I don't think It will noticeable. I provided a quick sketch of the details.

 

[Tomfh]

If this was my pool I would not consider it acceptable to have such uneven bearing pressures, nor would I consider 1cm “not noticeable” over 3m. 1cm means grout lines will not be parallel with the water surface. I would even out the bearing stresses.

 

[Gus14]

What would even the bearing stresses ?
I increased the columns loads by about 300 kn in case of future additions, so the actual laod should be about 350 Kn. I will try to give alternative of these two columns for future permits

 

[MIStructE_IRE]

Can you not just do a square pad footing centred beneath the column but poured integral with the pool base? Detail the column within the pool wall right down to the pad. (Assuming this is all new and you’re not proposing to load an existing pool?!)

Edit - just saw the property boundary line - doh! Still, can you do add i said above but just design an eccentric pad potted integral with the pool base?

 

[Gus14]

MIStructE_IRE, For such loads the footing would require a strap beam that would go through the pool footing and wall to the nearest opposite column ( 6 meters distance ). Since it won't be possible to make the footing load coincide with the center of mass (due to the large area of the pool foundation ) I think it will act more like a continuous foundation and would result in high negative moments (require 20Y18 probably). But it would even out the stresses I guess.