VERTICAL MOTION OF RIGID FOOTINGS.
MICHIGAN UNIV ANN ARBOR COLL OF ENGINEERING
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This work deals with the vertical mode of vibration of a rigid circular footing resting on a plane soil surface and excited by a vertical time-dependent force in the axis of symmetry. It is assumed that the subsoil can be considered as a perfectly elastic, isotropic, and homogeneous half space. First an approximate theoretical solution is developed for the steadystate motion of the above half-space model. This solution differs from previously published solutions in that it includes all frequencies of excitation. It is then shown how the transient response due to a pulse-type loading can be calculated from the steady-state solution by a simple Fourier technique, and a computer program using this technique is presented. Parallel with the above development it is shown that the elastic half-space model behaves very similarly to a simple damped oscillator, and the author proposes the use of a simplified analog of the mass-spring-dashpot type for practical calculations. The above theoretical results are supported by the presentation of both steady-state and impact tests performed by other researchers. Author