why no self weight of foundation is included in net ultimate bearing capacity formula

[hemanthpds]

 

[jayrod12]

I may be wrong, but it's typically because the foundation material displaces existing soil. And the weight is typically comparable between the two so the difference can be neglected.

 

[HENRYZAU]

Self weight is treated as a a load.

 

[msquared48]

Kinda why high rises are tried to be set into the ground to a target compensating depth...

Mike McCann, PE, SE (WA)

 

[EireChch]

HENRYZAU - for me it is not always a load. For relatively small foundations, strip footings etc it is typically ignored as it is similar to soil unit weight.

Where larger foundations are used eg thick Mat slab then it may be considered.

 

[MotorCity]

The foundation weight is a load, it is independent of the capacity.

 

[Okiryu]

I think also that the weight of the foundation is considered as load. Very few times bearing capacity controls the design so I do not worried too much about it. I just give an allowable bearing pressure based on settlement requirements to the structural engineer for certain depths and he/she will take care of no exceeding this pressure at the bottom of the footing. The pressure calculated by the structural should include the weight of the footing.