Influence functions of structures bonded to a saturated elastic half-space.
Item
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Title
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Influence functions of structures bonded to a saturated elastic half-space.
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Identifier
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AAI8820916
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identifier
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8820916
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Creator
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Xu, Jimin.
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Contributor
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Adviser: Mumtaz K. Kassir
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Date
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1988
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Civil
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Abstract
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This dissertation is concerned with the propagation of harmonic waves generated by a moveable rigid strip footing in contact with a saturated porous elastic half-space. The problem is formulated within the framework of Biot's classical theory of two-phase media in which the solid portion obeys the laws of linear elasticity and the fluid is governed by Darcy's law. Linear hysteretic damping characteristics of the medium are included in the constitutive relations. Integral Transform techniques are used to reduce the mixed boundary-value problem of a welded (and smooth) surface footing to a set of coupled Fredholm integral equations of the first kind and a numerical solution is provided. Frequency-dependent interaction functions (stiffnesses and radiation damping coefficients) of two typical soil samples consisting of saturated dense sand and saturated medium soft clay are computed and exhibited graphically to reveal the influence of pore water, permeability effects and hysteretic damping characteristics of the medium. It is concluded that the impact of pore fluid on the influence functions is quite substantial.;Soil hysteretic damping ratios ranging from 0% to 10% are assumed to study the impact of non-linearity of actual soil media on the influence functions. The results obtained indicate considerable increases in the radiation damping coefficients for all three modes of response, especially for the sandy material. Moderate changes in the stiffnesses are observed due to the hysteretic damping effect.;A parametric study to reveal the impact of soil permeability on the type of contact condition assumed between the surface footing and the underneath-half-space is also carried out. Appreciable differences between the welded and smooth contacts for all three modes of response are indicated when the half-space is fully saturated.;The differences between the responses of the sand and clay are mainly reflected in the type of the contact conditions between the footing and the underneath-half-space. The results indicate that the clay material is more sensitive to the type of contact than the sandy material.;Finally, it is worth mentioning that the results presented here are useful in determining the response of surface structures to dynamic loading, in particular, seismic excitations and machine vibrations. (Abstract shortened with permission of author.).
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
