Design Forces
Due to the no-tension (and thus nonlinear) nature of the finite element analysis conducted for continuous footings, the analysis results for a given load combination cannot be expressed as an additive sum of a given number of load cases. Rather, the analysis of each footing must be conducted for each specified load combination.
Once the analysis has been performed the soil spring results for the soil load combinations are used to compute the total stress and maximum stress on the soil. The results from the concrete load combinations are used to compute the force under the footing for the structural design of the footing.