Resistance of Shallow Footings to Moment Loads during Seismic Events

The kinematic approach of limit analysis is employed to account for inertial effects caused by seismic loads. In addition to a footing’s capacity to carry vertical and horizontal loads, the method is adapted for calculating the resistance to possible moment loads that may be transferred to the foundation soil from the superstructure. A foundation soil collapse mechanism that is sensitive to moment loads is utilized in the analysis. This mechanism transitions to a more common translational collapse in the absence of moment loads. The Mohr-Coulomb strength criterion was used in the analysis. While the limit load on the strip footing is grouped into components dependent on the cohesion, overburden, and the weight of the foundation soil (in addition to the internal friction angle), this study was focused on the component dependent on the foundation soil weight. The outcome of calculations demonstrated that the mechanism used in the analysis yields more conservative results than other methods. Considering that the analysis employed yields the upper bound to the limit load, the results appear to be more accurate than those considered for comparison.