Bearing Capacity Factors for Ring Foundations

Bearing capacity factors because of the components of cohesion, surcharge, and unit weight, respectively, have been computed for smooth and rough ring footings for different combinations of ri/ro and ϕ by using lower and upper bound theorems of the limit analysis in conjunction with finite elements and linear optimization, where ri and ro refer to the inner and outer radii of the ring, respectively. It is observed that for a smooth footing with a given value of ro, the magnitude of the collapse load decreases continuously with an increase in ri. Conversely, for a rough base, for a given value of ro, hardly any reduction occurs in the magnitude of the collapse load up to ri/ro≈0.2, whereas for ri/ro>0.2, the magnitude of the collapse load, similar to that of a smooth footing, decreases continuously with an increase in ri/ro. The results from the analysis compare reasonably well with available theoretical and experimental data from the literature.