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Equivalent Period and Damping of Soil-Structure Systems with Embedded Foundations in Layered Soil

Keshavarz, Mohammad Reza | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 51433 (53)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Ghannad, Mohammad Ali
  7. Abstract:
  8. The main purpose of this study is to estimate the natural frequency and damping ratio for soil-structure systems with embedded foundation with sufficient accuracy. The results are then compared to guidelines in current seismic codes. This is done through an extensive parametric study using a set of non-dimensional parameters, which define the soil-structure systems. For this purpose a simplified soil-structure model is used. Although more rigorous models and numerical solutions are available, they are time consuming and not suitable for parametric study. Existing formula for seismic provisions for the equivalent period and damping ratio of soil-structure systems are based on studies on surface foundations on the half space. Nevertheless, to extend the regulations for foundations on the layered soil and embedded foundations, a guideline is provided using a set of empirical coefficients. By applying the outcomes of this work, the accuracy of the current regulations and whether they are conservative or non-conservative, is looked into. It is established that for the systems with embedded foundation, using the current seismic empirical regulations leads to underestimate and overestimate, while the depth index is assumed to be constant. Increasing embedment ratio leads to underestimate and decreasing embedment ratio with regard to depth index leads to overestimate
  9. Keywords:
  10. Natural Frequency ; Damping Ratio ; Embedded Foundation ; Cone Models ; Layared Soil ; Soil-Structure Interaction

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