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The Effect of Subterranean Levels’ Flexibility on Multi-component Foundation Input Motion

Vakili, Masoumeh | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49800 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghannad, Mohammad Ali
  7. Abstract:
  8. In this research the flexibility of subterranean levels on foundation input motion (FIM), especially rocking component is investigated through parameter analyses. The so-called motion is induced as a result of kinematic soil-structure interaction (SSI). The foregoing interaction reduces the translational component of foundation input motion in rigid embedded foundations when compared to the free-field motion (FFM), as well as yielding rocking component in the foundation. On the other hand, increasing the embedment depth which is equivalent to the presence of subterranean levels in a building decreases the commonly-held “rigid” assumption’s accuracy for the embedded part. Given this effect, investigating the variation of foundation input motion along with the flexibility of the embedded part becomes. Modelling has been carried out in a finite element software, namely ABAQUS. The models is subjected to vertically propagating shear wavs and is analyzed with in a direct method in the frequency demain. In order to take into account the kinematic soil-structure interaction, superstructure is not modelled and only the stiffness of the foundation regardless of its mass is considered in the calculations. Moreover, a linear behavior is assumed for the soil. Firstly, study is carried out for a completely rigid foundation and the results are reported and compared in terms of transfer functions with the data in the literature. Furthermore, introducing an index for the flexibility of the foundation allows for the flexibility consideration in transfer functions. Results indicate that the influence of foundation flexibility on the translational component of the input motion can increase the translational component in relation to the rigid foundation. Neverthless, the amplitude of the rocking component is significantly reduced. It is shown that in foundations with high ratios of width to depth, otherwise known as shallow foundations, rocking component is slightly influenced by the above-mentioned phenomenon
  9. Keywords:
  10. Kinematics Interaction ; Foundation Fleaxibility ; Soil-Structure Interaction ; Subterranean Levels ; Foundation Input Motion (FIM)

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