Prediction of Footing Vibrations

by Milos Novak, Assoc. Prof., Engrg. Sci.; Univ. of Western Ontario, London, Ontario, Canada,


Serial Information: Journal of the Soil Mechanics and Foundations Division, 1970, Vol. 96, Issue 3, Pg. 837-861


Document Type: Journal Paper

Abstract: The vibrations of massive footings on soil are investigated. The experiments with bodies having variable mass and foundation base size are compared with the half-space theory. The amplitudes of vertical vibrations are found to be considerably larger than the theoretical values derived for a rigid body. This indicates that the soil behaves rather like an elastic stratum with reflection of elastic waves. Also the changes in resonant frequency with foundation base size correspond rather to an elastic stratum. Due to the nonlinearity of vibration the resonant frequency changes with amplitudes are not directly proportional to the exciting force. With some kinds of soil, these effects increase with decrease in amplitude. With sands nonlinearity is usually negligible. The effect of embedment is studied experimentally for both vertical and horizontal vibrations. The amplitudes decrease and the natural frequencies increase when the depth of embedment increases. The effect of undisturbed soil is much greater than the effect of the side fill.

Subject Headings: Vibration | Elastic analysis | Footings | Vertical loads | Resonance | Embedment | Half space

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