Effective depth of deep cantilevers

[aghaj]

I am designing a footing on rock. It is 800 deep and projects 300 beyond the column face. There are references available for deep simply-supported and continuous beams, for example, page 706 "Reinforced Concrete Structures"; Park and Paulay.
Could someone provide me corresponding information for a deep cantilever beam/ slab?

 

[ishvaaag]

Rigid concrete footings are designed when

free cantilever span from column face
------------------------------------- <= 2
depth of the footing

in accord with strut and tie methodology as per spanish code for RC concrete EHE section 59.4.1

For so small 0.3/0.8 cantilever to depth ratio you likely can even be served by mere even the safest assumption of the tensile strength or the concrete, or a mass footing; more so if the footing is keyed unto rock.