Optimal Surface for Elliptical Isolated Footings with Partially Compressed Contact Area

This study shows an optimal model to estimate the minimum area in contact with the soil for an EIF (elliptical isolated footing), assuming that the partially compressed area, that is, part of the surface below the base in contact with the ground, is compressed, and the other part is not compressed (the pressure of the ground is linear). There are works that show the minimum area for an elliptical isolated footing, but the surface below the base in contact with the ground is fully compressed. The model is developed by integration to determine the equations of the axial load and the two moments (X and Y axes) for the two cases. Two numerical studies are presented: Study 1 considers that the axial load varies, and the moments are equal and remain constant; Study 2 considers that the axial load varies, and the moments are different and remain constant. Two comparisons are also made with the model proposed by other authors (fully compressed area) and the new model (partially compressed area): In the first study, it is assumed that axial load and moment about the X-axis remain constant and moment about the Y-axis is variable; in the second study, it is assumed that the two moments remain constant and the axial load is variable. The results show that significant savings of up to 59.30% can be achieved in the first study and up to 65.67% in the second study in the area of contact with the ground. Another comparison is made between rectangular isolated footings and EIFs; the results indicate that savings of up to 63.18% can be achieved using EIFs. Therefore, this article will be of great help to specialists in foundation engineering.