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Seismic Analysis of Elevated Concrete Tanks with Endurance Time Method

Ghasemi Khalafloo, Pouya | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57256 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Esmaeil Poorestekanchi, Homayoun
  7. Abstract:
  8. Elevated concrete tanks have a wide range of applications in storing drinking water, firefighting, sewage, oil, toxic chemicals, and similar fluids. Therefore, due to their usage, these tanks are usually placed in the category of very important structures and vital arteries. Consequently, their design against seismic loads and their proper performance during earthquakes are of great importance. The endeavor time Analysis is a seismic analysis method in which the structure is subjected to an increasing dynamic excitation whose intensity gradually increases over time. The structure's response over time is examined, and based on the corresponding response to various levels of excitation intensity, the strengths, weaknesses, and performance of the structure are evaluated. In this research, the application of this method in the analysis of elevated concrete tanks using the Finite Element Method and with the assistance of ABAQUS software has been investigated. The model of the desired tank was initially validated using the results of reference research. Frequency analysis was conducted to obtain the structure's natural period for scaling earthquake ground motions according to the far-field FEMA695 earthquake and the ETA20in_xyz time functions at the 475-year earthquake hazard level. The results for time history analysis and endeavor time analysis are presented individually and averaged. Examining the results revealed that the use of endeavor time analysis can save more than three times the time in analyzing a specific model by regular time history method. Also, tank failure shapes and results of center of mass displacement in three directions, displacement of the highest point of the tank in two directions, stresses and strains, and base shear were examined and compared. Analyzing the results showed that the averaged results obtained from the endeavor time method and time history are in good agreement with each other, and the difference is not more than 20% in any case. The overall conclusion drawn from this research indicates the capability of the endeavor time method in estimating the responses of air concrete tanks with good accuracy in a much shorter time than conventional time history analysis, considering the fluid-structure interaction effect.

  9. Keywords:
  10. Elevated Tank ; Endurance Time Method ; Time History Analysis ; Seismic Assessment ; Elevated Concrete Tanks

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