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The Effect of Soli-Structure Interaction on Dynamic Characteristics of Structures with Embedded Fondation

Rahmani, Mohammad Taghi | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39134 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghannad, Mohammad Ali
  7. Abstract:
  8. Soil-structure interaction has significant effect on dynamic behavior of the super structure. This effect is usually investigated in two separate parts, i.e., the Kinematic Interaction effect and the Inertial Interaction effect. The first modifies the input ground motion to the foundation as a result of difference in soil and foundation stiffness. The later, i.e., the II effect, introduces the effect of soil flexibility and radiation of waves into the supporting medium on the response of the structure. These effects are usually considered by introducing a replacement oscillator with modified natural period and damping ratio subjected to foundation input motion. In the case of embedded foundation, the mentioned effects can be more important. A review of the literature and provisions reveals some discrepancies between proposed formulations for dynamic characteristics of soil-embedded foundation-structure systems that raise the necessity of more investigation on this issue. In this dissertation, a parametric research is performed to study the effect of soil-structure interaction on dynamic characteristics of structures with embedded foundation based on two basic methods, i.e., the complex eigen value method and the transfer functions method. In the first method, dynamic parameters are calculated in an eigen value extraction procedure for the first mode of vibration. In this investigation, first a set of approximate polynomial equations for soil impedances, based on numerical data are proposed. In the second method, dynamic parameters are calculated using transfer functions determined by total response of structures. Results are calculated in the presence and absence of the kinematic effect. To make results more practical, Analyses are performed for a vast range of non-dimensional parameters and then simplified equations are proposed using nonlinear regression analysis. Finally, The accuracy of dynamic parameters of soil-structure systems with surface and embedded foundations, proposed by EMA440 regulations, is investigated in the elastic range by comparison of implicit transfer functions
  9. Keywords:
  10. Soil-Structure Interaction ; Embedded Foundation ; Layared Soil ; Inertial Interaction ; Kinematics Interaction ; Effective Period ; Effective Damping

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