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Determination of Parameters Affecting the Linear Seismic Evaluation of Gravity Dams Using Nonlinear Analysis

Monazzam, Arash | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40893 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghaemian, Mohsen
  7. Abstract:
  8. Gravity dams are solid concrete structures that maintain their stability against design loads from the geometric shape and the mass and strength of the concrete. Because of their critical role in supplying portable and agricultural water and problems which would happen if they broke, it is required to consider their stability and keep them in safe conditions. They should be able to continue their function after a disaster such as earthquake. But most of them are aged dams with some have been built near faults. Indeed, there are some concerns regarding the performance of these dams under the effect of seismic loads. This research deals with performance evaluation of concerete gravity . The requirements to design and evaluate concrete gravity dams to have a predictable performance for specified levels of seismic hazard are discussed. Foundation of each dam is assumed to be rigid and massless. In this regard 10 records of earthquake have been used. Each of them are standardized due to foundation soil properties. The seismic input and performance levels are defined. The analysis and evaluation procedures and acceptance criteria for each performance level are described.They consist of linear and nonlinear procedures for estimation of seismic response and acceptance criteria that use demand-capacity ratios, damage control thresholds and post-earthquake stability condition to assess dam safety. In this study, it is tried to devise a set of criteria to make sure that we can trust on results from linear analysis and correct two criteria which was used by analysts for determining necessity of performing nonlinear analysis. These two parameters are cumulative inelastic time and percentage of overstressed area in dam`s structure. After 840 linear and nonlinear analysis for 3 concerete gravity dams (Bluestone, Folsom, Pineflat) we found out that for eathquake input records with PGA greater than 0.3g linear analysis is not adequate and nonlinear analyses must be done.






  9. Keywords:
  10. Linear Dynamic Analysis ; Nonlinear Dynamic Analysis ; Concrete Gravity Dam ; Performance Curve ; Cumulative Inelastic Time ; Overstressed Area

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