The meshed footing is supported on spring elements used to model the soil under the footing. The springs are defined to account for the soil stiffness under the footing and the area tributary to each support spring. The spring tributary area is calculated as half the length of the beam elements framing into a node multiplied by the width of the footing.

The soil springs at the ends of the footing are assigned a stiffness twice that resulting from the tributary area calculation. This method more accurately models the footing's deformation for cases in which the footing's centroid deforms more than its edges (see References # 4 and # 9 in Section 4.17). The resulting spring forces at the ends of the footing are then halved when converted to a soil stress.