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The dynamic stiffness of a foundation embedded in a multiple-layered halfspace is calculated postulating one-dimensional wave propagation in cone segments. In this strength-of-materials approach the sectional property of the cone segment increases in the direction of wave propagation. Reflections and refractions with waves propagating in corresponding cone segments occur at layer interfaces. Compared to rigorous procedures the novel method based on cone segments is easy to apply, provides conceptual clarity and physical insight in the wave propagation mechanisms. This method postulating one-dimensional wave propagation in cone segments with reflections and refractions at layer interfaces is evaluated, calculating the dynamic stiffness of a foundation embedded in a multiple-layered halfspace. For sites resting on a flexible halfspace and fixed at the base, engineering accuracy (deviation of ±20%) is achieved for all degrees of freedom with a vast parameter variation. The behaviour below the cut-off frequency in an undamped site fixed at its base is also reliably predicted. The accuracy is, in general, better than for the method based on cone frustums, which can lead to negative damping. Copyright © 2003 John Wiley & Sons, Ltd.
Authors:Wolf, JP and Preisig, Matthias
Index Terms:Soil; SoilGroup; dynamic soil-structure interaction; foundation vibration; layered halfspace; cone model; dynamic stiffness; embedded foundation
Further Information:Date published: 2003