Weiming Liu

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


In this dissertation a comprehensive investigation on the dynamic characteristics of turbine-generator-foundation systems is performed. All the major components of the system, including turbine-generator casing, shaft, rotors, journal bearings, deck, piers, foundation mat, piles, and soil medium, have been included. Full interaction between the turbine-generator set, the foundation superstructure, and the soil medium, is considered.;A hybrid method is proposed to establish the mathematical model for the turbine-generator-foundation system, which includes finite element discretization of turbine-generator and foundation superstructure, combined with a soil stiffness matrix derived from the dynamic Green functions of the soil. The soil is modeled as a transversely isotropic layered medium over a rigid bedrock. The analysis is conducted in frequency domain through complex frequency response analysis. The response in time domain is obtained by Fourier transform. The seismic excitation is represented as the control motion on the ground surface, which is generated as an artificial earthquake. Both inertial and kinematic interactions are included.;Several computer programs, including a general purpose finite element program, a program to formulate soil stiffness matrices, and a program to generate artificial earthquake ground motion records, have been written by the author, which can be used to analyze most soil-structure interaction problems, such as machine foundations, buildings, piles and pile groups, tunnels, and dams. A series of parametric studies on strip foundations, single piles, pile groups, and three-dimensional mat foundations is presented to demonstrate these applications. Particular attention is paid to the effect of soil anisotropy on the structural response. The effect of soil anisotropy on the foundation response is found to be significant in most cases.;A 300MW turbine-generator-foundation system is analyzed as an application of the developed mathematical model and computer codes. Excitations from rotor unbalances and earthquakes are considered. The influence of turbine-generator casing and soil anisotropy on the response of the system is explored. It is found that the presence of casing and soil anisotropy strongly influences the displacements and internal forces of the system under rotor unbalance excitation. Under seismic excitation, however, although the presence of casing and soil anisotropy does affect the displacements of the system, their effect on the internal forces of the system is minimal.



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