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Evaluation of Soil Contribution to Seismic Response of Soil-Structure Systems Using Recorded Data During Small-scale Earthquakes

Vaseghi Amiri, Shaghayegh | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46866 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghannad, Mohammad Ali
  7. Abstract:
  8. Soil-Structure Interaction (SSI) has been widely studied theoretically and experimentally due to its importance effects on the responses of structures. In experimental studies, acceleration responses recorded during previous earthquakes are generally used in order to investigate the contribution of underlying soil to the response of soil-structure systems. Since acceleration responses are affected by higher modes of vibration, studying the effect of SSI on dynamic characteristics of higher modes are of great importance in these studies. However recent theoretical studies indicate that the influence of SSI on the higher vibrational modes is very much dependent on the behavioral model (bending or shear deformation) of the upper sub-structure. That is while in most experimental studies, simple models are used for upper sub-structure in order to estimate the soil's contribution to the response of soil-structure systems. Here, the roll and importance of the modelling of sub-structure in estimating the soil's contribution to the response of soil-structure systems have been investigated. It has been tried to obtain more reliable estimation of the contribution of soil to the system's response from real earthquake data by assuming more realistic behavioral models for upper sub-structure. For this purpose, upper sub-structure is considered as a frame with bending-shear deformation in analytical models. The underlying soil is modeled with point springs and dampers. Modal analysis of the soil-structure system is carried out based on complex eigenvalue analysis due to non-classical damping matrix. In order to identify soil-structure systems, transfer function of acceleration response between two different levels of the system is defined. By applying optimization algorithms, this transfer function is used to identify the defining parameters of the system which its absolute acceleration response histories are available at two or more levels. The purposed method is then validated with analytical models and instrumented buildings using artificial and real floor response data. It is concluded that the method is capable of anticipating the defining parameters of soil-structure systems with bending-shear frame model for upper sub-structure. It is also shown that two structures with different lateral resisting systems and different soil contribution but with identical responses can be found. Moreover investigating instrumented buildings indicates that by using purposed method a good estimate of the systems' response can be provided
  9. Keywords:
  10. System Identification ; Soil-Structure Interaction ; Shear-Bending Behavioral Model ; Seismic Acceleration Response

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