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Evaluation of the Effect of Temperature Gradient on the Dynamic Behavior of Concrete Arch Dams

Moghaddas Jafari, Reyhaneh | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39446 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Rahim Zadeh Rofooei, Fayyaz
  7. Abstract:
  8. Concrete arch dams, because of their special shape as a 3-D huge shell which is fixed from three sides, are very sensitive to temperature and its variation. Therefore, it is required to include the temperature variations and their related thermal stresses and strains in the safety analysis of dams. In this research, the effect of applying the thermal gradients caused by the most critical thermal conditions, on dynamic behavior of concrete arch dams was studied. For this purpose, first a roughly exact 3-D finite element model of Karoon ІV arch dam was prepared by ANSYS program. Then, the temperature distribution through the dam thickness was determined by Stucky-Derron method and in a more accurate way by ANSYS program for two critical summer and winter cases. The effects of the both reservoir with the normal and minimum water level and foundation on the seismic response of the dam, is considered taking into account the dam-foundation and dam-water interactions with the earthquake load being applied to the reservoir. Also, in addition to the water compressibility, the wave absorbing boundaries both in the far end of the reservoir with the full absorption and in the reservoir bottom with 15% absorption have been determined. Furthermore, three components of the earthquake records are simultaneously applied to the model. Finally, because of considering the foundation mass for creating more consistency between the true behavior and the mathematical model of the foundation which leads to the propagation of the earthquake waves within the foundation medium, the wave absorbing boundaries have been placed on the foundation sides. Afterwards, thermal, static, static (just with thermal loading), dynamic (without thermal loading for massed and mass less foundations) and dynamic with thermal loading analyses were carried out. According to the results, combining the thermal effects with the dynamic analysis would increase the maximum tensile stresses and decrease the maximum compressive stresses as well as algebraic values of the displacements in the dam body. Moreover, differences are also observed between the results of the analyses with the temperature distribution obtained by ANSYS software and Stucky-Derron method. Furthermore, considering the foundation mass reduces the stresses and displacements in comparison to the case with mass less foundation
  9. Keywords:
  10. Concrete Arc Dam ; Dynamic Analysis ; Temperature Gradient ; Massed Foundation ; Karoon IV Dam

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