Vibration Analysis of Double Deck Floating Roof of Storage Tank in Cases of Tube, Ordinary and Thickened Foam Seals

Vibration of a floating roof in cases of tube and foam seals has been analyzed by ANSYS. Fluid-Structure Interaction (FSI) and sloshing phenomenon have been considered. Modal responses, time waves and frequency spectrums of the roof vibrations in the two sealing cases were evaluated during horizontal seismic excitation of the tank base. Then, the effects of the main mechanical factors of the seal on the roof vibration were investigated. The roof vibration amplitude in the foam sealing case was considerably lower than that in the tube sealing case due to more damping of the foam seal. Also, the foam sealing case had higher natural frequency than the tube sealing case due to more tank-axial (vertical) shear modulus of the foam seal in relative to the tube seal. Regarding this result, the foam seal was vertically added by 50% and the tank base was seismically excited again. It was seen that this improvement in thickness has more contribution to the floating roof vibration mitigation.