Dimensioning Footings Subjected to Eccentric Loads

An approach often used to determine the bearing capacity of shallow foundations subjected to eccentric loading is based on Meyerhof's concept of a reduced effective area. The effective area is the area of greatest length such that its centroid coincides with the resultant load. The effective width of the reduced area is defined as the effective area divided by its length. The procedure for determining the effective dimensions of rectangular footings with one-way eccentricity is straightforward but the process is complex and time-consuming when the eccentricity is in both directions. Depending on the magnitudes of eccentricities e_l and e_b in the directions of the length, L, and width, B, of the footing, respectively, the effective area is one of four possible shapes. To aid the engineer in the design of eccentrically loaded footings, analysis charts are prepared which yield normalized reduced dimensions as a function of normalized eccentricities, e_l/L and e_b/B, for the four cases. An analysis chart is also prepared for determining normalized reduced dimensions of circular footings as a function of the normalized eccentricity, e_r/R.