Dynamicl characteristic analysis of 15×10~4m~3 vertical liquid storage-tanks
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Large-scale unanchored vertical liquid storage tanks are being applied extensively,its dynamic parameters,such as the natural frequency and mode shape,are very often used in seismic engineering.The natural mode of 15×104m3 storage tank was analyzed by ADINA finite element technique using spring element to simulate foundation,and considering the liquid-structure interaction effect.The results show that: there is small difference between the finite element technique and the well-known code formula on mode analysis of tanks;the vibration forms of the low-frequency segment of 15×104m3 storage tank are various,among which cosnθ、sinnθ beam vibrations are the leading one,the vibration forms of the liquid are simple,namely cosnθ、sinnθ beam vibration;the frequencies of liquid-structure coupled vibration are sensitive to foundation stiffness,are followed by the liquid height and the ratio of tank height to radius,and are insensitive to the thickness of tank wall;sloshing frequencies of liquid are insensitive to foundation stiffness as well as the thickness of tank wall,and are sensitive to liquid height as well as the ratio of tank height to radius.Keywords:
Slosh dynamics
Adina
Foundation (evidence)
Natural frequency
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The liquid tanks are installed in ships or offshore platforms,the impact of liquid medium in the liquid tanks on vibration performances of the hull should not be overlooked.The paper developed a finite element mathematical model of fluid-structure interaction( FSI) with the steel tank. The FSI dynamics in different liquid heights in liquid tanks were numerically simulated and analyzed by the FEM software ADINA. By adopting LMS structural mode analysis system,the paper compared inherent frequencies and modes of low-frequency-vibration. Simulation results are in good agreement with the experimental ones,which verifies the effectiveness of the simulation method. The findings and methods can be reference for fluid structure interaction.
Adina
Fluid–structure interaction
Mode (computer interface)
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Take 15×104m3 storage tank as an example,its model analysis was carried out by ADINA finite element technique and criterion method.The results show that: there is little difference between the finite element technique and the well-known code formula on the modal analysis of tanks;the vibration forms of the low-frequency segment of 15×104m3 storage tank are various,among which cosnθ,sinnθ beam vibration is the leading one,the vibration forms of the liquid is single,namely cosnθ,sinnθ beam vibration.The liquid-solid coupling frequency of tanks is sensitive to the ground hardness variation,and the liquid shaking frequency is sensitive to the height variation of storing liquid.
Adina
Slosh dynamics
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Base isolation
Base (topology)
Matrix (chemical analysis)
OpenSees
Fluid–structure interaction
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Citations (72)
Seismic isolation is a well-known method to mitigate the earthquake effects on structures by increasing their fundamental natural periods at the expense of larger displacements in the structural system. In this paper, the seismic response of isolated and fixed base vertical, cylindrical, liquid storage tanks is investigated using a Finite Element Model (FEM), taking into account fluid-structure interaction effects. Three vertical, cylindrical tanks with different ratios of height to radius (H/R = 2.6, 1.0 and 0.3) are numerically analyzed and the results of response-history analysis, including base shear, overturning moment and free surface displacement are reported for isolated and non-isolated tanks. Isolated tanks equipped by lead rubber bearings isolators and the bearing are modeled by using a non-linear spring in FEM model. It is observed that the seismic isolation of liquid storage tanks is quite effective and the response of isolated tanks is significantly influenced by the system parameters such as their fundamental frequencies and the aspect ratio of the tanks. However, the base isolation does not significantly affect the surface wave height and even it can causes adverse effects on the free surface sloshing motion.
Slosh dynamics
Base isolation
Free surface
Base (topology)
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Based on velocity potential theory,the vibration characteristic equation of rectangular liquid tank is derived.Element mass matrix of free surface and element stiffness matrix inside the liquid are also calculated by finite element method(FEM) codes.The relation between liquid sloshing frequencies and the liquid height is analyzed for the double bottom tank,and the numerical results are compared with the analytical solution,which shows that the proposed method is available.
Slosh dynamics
Added mass
Matrix (chemical analysis)
Free surface
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Many tanks are installed in ship and marine structures. They are often in contact with inner or outer fluid, like ballast, fuel and cargo tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks in contact with fluid near engine and propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tanks. Many authors have studied vibration of cylindrical and rectangular tanks containing fluid. Few research on dynamic interaction among tank walls through fluid are reported in the vibration of rectangular tanks recently. In case of rectangular tanks, structural coupling between adjacent panels and effect of vibration modes of multiple panels on added mass have to be considered. In the previous report, A numerical tool of vibration analysis of a 3-dimensional tank is developed by using finite element method for plates and boundary element method for fluid region. In this paper, the coupling effect between panels of a tank on added mass of containing fluid, the effect of structural constraint between panels on each vibration mode for fluid region and mode characteristics in accordance with changing breadth of the plates are investigated numerically and discussed.
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Added mass
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Slosh dynamics
Added mass
Fluid–structure interaction
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Slosh dynamics
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This paper take the typical train liquid storage tank as research object, the fluid-solid coupling dynamic responses of the tank are analyzed under the track irregularities using finite element software ANSYS. The research indicates that the difference of the liquid volume in tank has great influence to the structural stress and strain. When the tank is not filled with liquid, the liquid has large-scale amplitude sloshing, and the stress and strain are much bigger than the static condition. But if the tank is full of the liquid, the stress and total amount of deformity of the tank can be obviously reduced.
Slosh dynamics
Harmonic
Stress–strain curve
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Slosh dynamics
Rayleigh quotient
Natural frequency
Flexibility method
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