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Investigating the Effect of Soil-Structure Interaction on the Buckling Behavior of Anchored Steel Cylindrical Tanks using Absorbing Boundaries

Khaki, Taha | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57945 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Rahimzadeh Rofooei, Fayaz; Sobhan, Mohammad Saeed
  7. Abstract:
  8. This research investigates the effect of soil-structure interaction on the buckling behavior of an above-ground storage tanks. For this purpose, a steel tank with a height-to-diameter ratio of 0.4 was selected. Four types of support conditions including a fixed-based condition and three soil islands with a depth of 30 meters, assuming a uniform stiff soil and a two-layered soil consisting of stiff and medium soil, and a three-layer soil with stiff, medium, and soft layers. The tank and soil were modeled using the finite element method, and absorbing boundaries were applied around the soil island to simulate the semi-infinite soil domain. After validating the modeling through parametric and dynamic analysis, the numerical model’s accuracy was ensured. Incremental dynamic analyses were then performed using 11 far-fault earthquake records with peak ground accelerations (PGA) ranging from 0.1g to 0.5g in increments of 0.1g to extract buckling capacity curves, critical loads, and hydrodynamic pressure distribution. The results indicate that as the soil stiffness at the tank foundation decreases, buckling of the tank wall occurs at higher levels of PGA, with this threshold being up to 70% higher in soft soil compared to a fixed-based condition. However, it is concluded that PGA is not a suitable criterion for determining the buckling capacity of the tank. Instead, when considering base shear as a more precise indicator of tank behavior, the buckling capacity generally decreases in the presence of soil, showing reductions of 5.6%, 3.2%, and 2.5% for stiff, medium, and soft soils, respectively, compared to the fully fixed-base condition. Therefore, soil-structure interaction, assuming linear soil behavior, has a negative impact on the buckling capacity of the tank. Additionally, the hydrodynamic pressure distribution was analyzed as another evaluation criterion, revealing that different foundation conditions alter the pressure distribution. The normalized pressure distribution is found to be nearly identical in the fixed, stiff, and medium soil conditions, whereas in soft soil, the pressure in the middle and upper regions of the tank can be up to 10% higher than in the fixed-based condition
  9. Keywords:
  10. Anchored Cylindrical Tank ; Soil-Structure Interaction ; Seismic Analysis ; Absorbing Boundary ; Incremental Dynamic Analysis ; Tank Bucking

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