Response of Embedded Footings to Vertical Vibrations

Field vibratory tests have been carried out to study the effect of embedment on the vertical response of footings. Steady-state vibration tests indicate decrease of maximum amplitudes of motion and increase of resonant frequencies as a consequence of embedment. A lumped parameter analog with the inclusion of Coulomb friction damping is suggested to explain the dynamic behavior of embedded footings. A simple procedure by which the constant frictional force of the Coulomb friction damping can be evaluated has been described. The suggested procedure takes into consideration the relevant physical characteristics of the interface between the foundation walls and the surrounding soil. The field test data obtained by the writers as well as those published by other investigators elsewhere are compared with the values predicted by the proposed analog. The correlation between the available experimental data and the predicted values is satisfactory.