| Summary: | 博士 === 國立臺灣科技大學 === 營建工程系 === 94 === This dissertation presents new simplified models to simulate the dynamic behavior of unbounded soil. The behavior of the soil is investigated for a rigid foundation subjected to vertical, torsional, horizontal, and rocking vibrations. The proposed simplified model comprises masses, springs, and dashpots. Through the developed theory of equivalent models, the modeling parameters are obtained by a more efficient method without using lengthy optimization techniques.
The dynamic responses of a foundation-soil system using the proposed model are well consistent with those obtained by the half-space theory. It is also found that the proposed model with fewer parameters may be as accurate as most existing lumped-parameter models. However, for evaluating the horizontal and rotational foundation responses, the proposed model is found to have more accurate results than existing models since the developed theory may adequately consider the coupling effect of horizontal and rocking motions. The rotational responses of embedded foundations to rocking moments may be significantly underestimated without considering the coupling effect.
Furthermore, the dynamic responses of a building-soil system using the proposed simplified model are also investigated and found to agree well with the results obtained by the half-space theory and by the numerical computer program. These verifications for the proposed model in soil-structure interaction analysis are performed in both frequency domain and time domain. The building-soil system studied is subjected to harmonic forces, loading time histories, and seismic excitations, separately. The analyzed results indicate also that the structural responses may be deviated without simultaneously considering the coupling of horizontal and rocking motions for the building structure having a deep embedded ratio and a high storey stiffness ratio.
The proposed method for developing simplified models may be effectively and efficiently applied to practical problems involving soil-structure interaction such as machine foundation vibration and seismic structural analysis.
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