Isolated and Combined Footings

Individual columns are generally supported on isolated footings. A typical isolated footing is shown in Figure. This arrangement is suitable when the column spacing are large and the loadings are even. Also the soil should have low compressibility and differential settlements are small. Alternatively, if the superstructure is flexible or if no secondary stresses develop due to provision for hinges and adjustable pads, footings will prove satisfactory. When the foundation is designed to withstand bending moments and shear like steel columns for factories where very heavy loads are involved grillage foundations are used