Settlement and rotation of skirted square footing under eccentric loading in granular soil

The deformation behaviour of footing under the load from the superstructure is fundamental to foundation design consideration. The deformation of footing changes when subjected to moment along with the central vertical load. The application of moment on footing can be derived as a load eccentricity from the central axis. Due to the load eccentricity (moment), the footing is subjected to rotation (tilting) along with settlement. The average settlement of footing along the central axis also increases with the increase in load eccentricity for a constant load. In these circumstances, the deformation of the footing can be decreased by adding a circumferential skirt around the footing. A series of model tests have been conducted in dense sand on a square footing of 10 mm width (B). The skirt length (L) varies from 0 to 1B, and load eccentricity (e) ranges from 0 to 0.15B. The effect of the skirt length, footing embedment, and load eccentricity on the behaviour of load–settlement and moment–rotation curves have been presented. Based on the model test, empirical formulations have been developed to predict the settlement and rotation of skirted footings.