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Dynamic Responses of Arch Dams Subjected to Multiple Support Excitations

Sohrabi Gilani, Morteza | 2012

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 43838 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghaemian, Mohsen
  7. Abstract:
  8. Large structures such as dams, long span bridges and piping systems because of an extended interface with the ground as support and the earthquake wave propagation in foundation are subjected to the non-uniform excitations. In such cases, the standard dynamic analysis in which a uniform earthquake is used as an input data is not true and can lead to unrealistic results. In the present study, seismic responses of arch dams subjected to spatial variation of ground motions is investigated and compared with the standard methods. For this purpose the governing equations are implemented into the NSAD-DRI (comprehensive software for Nonlinear Seismic Analysis of Dams) and the seismic responses of Pacoima and Karun III dams are investigated based on the acceleration time histories recorded by the arrays installed on the dams.
    In the first step the recorded ground motions have been studied which their non-uniform nature have been clearly demonstrated. Recorded motions have shown that due to the finite speed of earthquake wave propagation, the ground motion is delayed at the abutment compared to the base of the dam, furthermore a topographic amplification at the abutment near the crest of the dam relative to the base is observed. The obtained results indicated that spatially varying earthquake assumption is in satisfactory agreement with the recorded displacement of the dam. Generally applying the base motion as the uniform excitation underestimates the crest displacements and the developed stresses in the dam body.
    It was concluded that when recorded ground accelerations at the dam foundation interface are employed as input into the analysis, the dam foundation interaction effects are implicitly included. Therefore, in the finite element model, the foundation was excluded which can greatly facilitate the modeling process
  9. Keywords:
  10. Concrete Dam ; Dynamic Analysis ; Time Delay ; Spatial Variation of Motion ; Nonuniform Excitations ; Topographic Amplification

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