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Seismic Analysis of Concrete Dam based on Numerical Modeling of Wave Propagation from Seismic Source to Site

Mohammadnezhad, Hamid | 2017

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 50387 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghaemian, Mohsen; Zafarani, Hamid
  7. Abstract:
  8. Safety assessment of existing dams and analysis and design of new dams as an important part of infrastructures of any country, hinges on proper and precise modeling of coupled system of dam-foundation-reservoir under appropriate seismic excitation. In this dissertation, effective methodology for seismic analysis of concrete dam, using finite element method, is presented which takes account for numerical modeling of wave propagation from excitation source to site and interactions between dam, foundation and reservoir. To model the effects of mass, wave propagation and radiotional damping in unbounded foundation as well as modeling the fault itself, two boundary conditions namely, free-field boundary condition and Domain Reduction Method (DRM) are implemented in ABAQUS software by the author. To verify the procedure, numerous examples are presented and results are compared with approved references which indicate the effectiveness of both said methods. After verification, Koyna concrete gravity dam is analyzed assuming unbounded massed foundation under vertical propagation of seismic excitation and results are compared with sub-structure method (EAGD-84) which again highlights the good conformity of results. In these analysis it was found out that foundation mass has immense effects on dynamic response of dams. After these analyses, inclined propagation of P and SV waves in half-space using finite element method was taken into account and a system of dam-foundation-reservoir was analyzed under inclined seismic wave propagation. Results indicated high dependency on type of wave and propagation angle. For more realistic simulation of earthquake and inclusion of seismic source, propagation path and site effects a hybrid method consisting of discrete wave number method and finite element method is presented. Using this hybrid method, Koyna dam is analyzed under specific earthquake scenario and with inclusion of fault. The merit of proposed methods in this dissertation against other methods are that, preserving previous advantages of finite element method, they can be used for high-precision simulation of wave propagation and scattering in unbounded environments for both academic and engineering problems. The hybrid method is also of great help for simulating of faults and real earthquakes
  9. Keywords:
  10. Massed Foundation ; Radiation Damping ; Dam-Reservoir-Foundation Interaction ; Seismic Analysis ; Concrete Dam ; Domain Reduction Method ; Inclined Wave Propagation

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