chapter  9
41 Pages

Ring Footings

WithSwami Saran

Shallow foundations are a common type of foundation usually provided for various important structures resting on good soil. Annular foundations are usually subjected to eccentric-inclined loads due to moments and horizontal thrusts in conjunction with the vertical loads. Ring foundations, besides being economical, are the only solution for the aforementioned structures, when the dual conditions of full utilization of soil capacity and no tension under the foundation are to be satisfied. This chapter illustrates some engineering application areas for the use of ring footings. Kumar and Chakraborty computed the bearing capacity factor for smooth and rough ring footings, using lower and upper bound theorems of limit analysis in conjunction with finite elements and linear optimization. Al-Smadi developed an analytical analysis for getting pressure-settlement and pressure-tilt characteristic of ring footings subjected to eccentric-inclined loads resting on either clay or sand. He also performed model tests on solid circular footing and ring footings subjected to eccentric-inclined load and resting on sand.