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Seismic Analysis of Concrete Gravity Dams Considering Layered Foundation Using Domain Reduction Method

Sotoudeh Foumani, Payam | 2021

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 54222 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghaemian, Mohsen
  7. Abstract:
  8. Nowadays, due to advancements in technology and processing power, earthquake engineering is moving toward more realistic modeling of actual problems in different fronts. In the case of considering seismic waves for design and analysis of concrete dams, numerous challenges exists due to complex nature of the problem which have absorbed abundant attention from a number of researchers around the world. In recent studies about earthquake input mechanisms, accounting for true nature of the foundation and applied earthquake have been hot topics. Therefore, in this thesis, thorough investigation on these effective factors in dynamic analysis of concrete dams is performed.In the first part of this study common assumption for vertical propagation of earthquake is utilized. Apart from considering layered foundation, the effects of introducing weak or strong layers of materials with different lengths, locations and orientations as well as investigating the possibility of exhausting the earthquake waves before they reach the dam structure are studied in this part. The results of this part, which are presented in three different sections, show that the stress levels in dam body are sensitive to modular ratio of the layers and the level of sensitivity is higher for lower modular ratios. The results also indicate that, when considering vertical propagation of earthquakes, the characteristics of the layer material, its location and thickness are more effective on dynamic response of the dam rather than their length or orientation. Besides, in the investigation of possibility of exhausting seismic waves, results show that by introduction of simple hollow holes in the foundation and careful arrangement of them, one can be successful in exhausting the earthquake waves before they reach the dam body.In second part of the thesis, the vertical propagation assumption of earthquake is dropped and the system is analyzed under desired inclined propagating earthquake.For this case, a system of dam-foundation-reservoir is analyzed under P or SV type earthquakes with desired angles of incidence and the effects of incident angle, frequency content of the earthquake and effects of surface wave presence on dynamic response of the dam are investigated. The results of this part show that vertical propagation assumption in general leads to underestimation in levels of stress in the dam body. With a more general view and considering participation percentage of P and SV waves in a realistic earthquake record, it seems that vertical propagation assumption could still be utilized for engineering purposes
  9. Keywords:
  10. Seismic Analysis ; Massed Foundation ; Wave Propagation ; Concrete Gravity Dam ; Dam-Reservoir-Foundation Interaction ; Inclined Wave Propagation ; Post Critical Angles ; P Earthquake Wave ; SV Earthquake Wave ; Layered Foundation

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