Research on the prediction of soil stiffnesses of spread footing-soil systems using Wave Activated Stiffness (K) or WAK tests was conducted. As discrete lumped-parameter model with a mass, spring, and dashpot was used to model the footing-soil systems. A large, heavy hammer with a soft, rubber tip, instrumented with a force transducer, was used to focus and record the impact energy at the lowest possible frequency. The footings were instrumented with geophones to record the velocity response. By attempting to initiate a low frequency vertical response of the footing-soil systems, the WAK test aims at predicting the initial static stiffness, and thus, the elastic settlement that would be observed in the initial, small-strain displacement stage of static loading.
