Several tanks have failed due to intolerable differential settlements, causing major problems in most cases. The objective of this study is to optimize the bottom plate of the tank so that the differential settlements are reduced to a minimum. Circular plates on an elastic half-space are investigated and the improvements in differential settlements are reported. The plates are loaded by a uniform pressure, and the effects of edge loads, edge moments, and elastic restraints at the edge are considered. A plate with two annular segments having fixed radii is investigated for optimal thicknesses. The plate is also optimized by varying both the radii and the thicknesses. Another plate with three segments is studied, varying the radii and the thicknesses. In all these cases, the plates are examined for a wide range of relative stiffnesses. For a specific relative stiffness, a plate with ten segments of fixed radii is studied. Also, the contact stress distribution is investigated for the case of the three-segment plate. During the study, the results are compared to a uniform plate. As an outcome, the differential settlement is significantly improved compared to the widely used uniform plate. / Master of Science