Shafqat Ullah, Mwaura Njiru, and Iraj H. P. Mamaghani
Abstract: Cylindrical steel storage tanks are more vulnerable to local buckling when subjected to external pressure, axial loading, or lateral ground motion. This paper presents the static and seismic nonlinear analysis of empty shell and liquid-filled (83.4%) steel storage tanks using finite element analysis (FEA) commercial software ABAQUS. Firstly, to substantiate the accuracy of FEA, a perfect cylindrical specimen is considered for buckling analysis. Based on this study, the cylindrical steel storage tank is seismically excited in the horizontal direction under two real-world ground motions (Friuli 1974 and Northridge 1994 earthquake). Initially, the tank is subjected to the gravity load and hydrostatic nonlinear analysis in steps 1 and 2 for 1 second each. Then the dynamic implicit analysis is carried out for 20 and 30 seconds in each case to evaluate the seismic behavior of the storage tank. The results from static analysis show that the FEA buckling pressure is closely matched with the test and theoretical solution. Furthermore, from the parametric study, Nonlinear analysis shows that the maximum von Mises and hoop stresses are more dominant near the tank base. The response acceleration, distribution of the stresses including longitudinal and circumferential (hoop) stresses, and maximum pressure vs time response are evaluated. The results from seismic nonlinear analysis indicate that the tank experienced a maximum acceleration response when subjected to the Friuli earthquake which is slightly higher than the tank's response under the Northridge earthquake. Furthermore, the response shows that maximum excitation is in the lateral direction (x-component) where the ground motion is applied at the storage tank's base. The other components (y and z-components) do not significantly affect the tank's seismic performance. it can also be seen that the response in Z-direction is almost negligible. In case of the Northridge input excitation, the x-component represents the maximum response of the tank and the remaining components (y and z-components) does not have significant contribution in the tank excitations. Lastly, the pressure response shows that the tank under Friuli seismic excitation has a maximum peak compared to the tank subjected to the Northridge earthquake.
Keywords: Cylindrical steel tank, Local buckling, Fluid-structure interaction, Seismic analysis, FEA ABAQUS.
Date Published: September 18, 2024 DOI: 10.11159/ijci.2024.017
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