Buckling at the Top of a Fluid-Filled Tank During Base Excitation

An explanation is provided for the earthquake-induced damage observed at the top of liquid storage tanks. An analysis is developed and the results are compared with experimental work. The basic steps of the analysis, which is developed for the general dynamic response of fluid-filled tanks under horizontal ground excitation, are first presented. In this analysis, the structural displacements are expanded in appropriate series forms which involve both rigid body and flexible components. The latter components are expressed as linear combinations of terms, each of which is a product of a function with assumed spatial dependence and an unknown time-dependent function. These time functions are then determined from the solution of the fluid/structure system equations, which are set up by employing Hamilton’s principle. In the present work, results are obtained and compared with model tests carried out at Caltech, during which buckling was observed at the top of the tank under a known base excitation history. Computing analytically the corresponding pressure distribution and using the BOSOR computer code for the buckling computations, a value for the amplitude of the ground acceleration which results in buckling at the top of the tank is calculated. Good correlation with the test work is obtained.

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The effects of input earthquake characteristics on the nonlinear dynamic behavior of FPS isolated liquid storage tanks

Journal of Vibration and Control ◽

10.1177/1077546316655914 ◽

2016 ◽

Vol 24 (7) ◽

pp. 1264-1282 ◽

Cited By ~ 3

Author(s):

Saman Bagheri ◽

Mostafa Farajian

Keyword(s):

Passive Control ◽

Base Isolation ◽

Ground Motions ◽

Storage Tanks ◽

Ground Acceleration ◽

Pendulum System ◽

Aspect Ratios ◽

Liquid Storage ◽

Isolation Systems ◽

Friction Pendulum

There are several methods to reduce the seismic damages in liquid storage tanks. One of these methods is to use passive control devices, in particular seismic base isolators. Among the different base isolation systems, the Friction Pendulum System (FPS) whose period does not depend on the weight of the system is more appropriate for isolation of liquid storage tanks. The aim of this paper is to investigate the effects of peak ground acceleration (PGA) and pulselike characteristics of earthquakes on the seismic behavior of steel liquid storage tanks base isolated by FPS bearings. In addition, impact effects of the slider with the side retainer are investigated, as well as effects of tank aspect ratio, isolation period and friction coefficient. The obtained results of tanks with different aspect ratios indicate that the responses get more reduced due to isolation under far-field ground motions compared to near-fault ground motions. It is also seen that the response of a base isolated tank is affected when contact takes place with the side retainer of the FPS.

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Fragility Analysis of Base-Isolated Liquid Storage Tanks under Random Sinusoidal Base Excitation Using Generalized Polynomial Chaos Expansion–Based Simulation

Journal of Structural Engineering ◽

10.1061/(asce)st.1943-541x.0001518 ◽

2016 ◽

Vol 142 (10) ◽

pp. 04016059 ◽

Cited By ~ 11

Author(s):

Sandip Kumar Saha ◽

Kheirollah Sepahvand ◽

Vasant A. Matsagar ◽

Arvind K. Jain ◽

Steffen Marburg

Keyword(s):

Polynomial Chaos ◽

Polynomial Chaos Expansion ◽

Fragility Analysis ◽

Chaos Expansion ◽

Base Excitation ◽

Storage Tanks ◽

Generalized Polynomial Chaos ◽

Liquid Storage ◽

Generalized Polynomial

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The Formulations of Shear Force and Overturning Moment of the Large-Upright-Unanchored Industrial Liquid Storage Tanks Subjected to Horizontal Ground Excitations

Volume 8: Seismic Engineering ◽

10.1115/pvp2005-71043 ◽

2005 ◽

Author(s):

Mutlu Ozer

Keyword(s):

Shear Force ◽

Excitation Frequency ◽

Response Analysis ◽

Tank Wall ◽

Storage Tanks ◽

Base Shear ◽

Ground Acceleration ◽

Dynamic Coefficients ◽

Liquid Storage ◽

Overturning Moment

The dynamic response analysis is performed for the formulations of shear force and overturning moment of the large-upright-unanchored industrial liquid storage tanks subjected to horizontal ground acceleration. As the tank is accelerated in the horizontal direction, it tends to uplift from its foundation, and hydrodynamic pressures on the tank wall vary with height in non-linear fashion. In this study, the distribution of hydrodynamic pressures and its center are directly correlated to formulate shear force and overturning moment. Initially, the equations of shear force and overturning moment derived by assuming hydrodynamic pressures exerted on tank wall vary in parabolic trend. Then derived equations are multiplied by dynamic coefficients, which are basically the function of peak ground acceleration, excitation frequency and the ratio of liquid’s height to radius of tanks. Dynamic coefficients are formulated through the shake table experiment of the model tanks excited by computer generated ground motion. The equations proposed in this paper for base shear and overturning moment are only the function of total weight of tank, the ratio of liquid’s height to radius, specific weight of liquid and dynamic coefficients for shear force and overturning moment. Therefore, proposed equations are very simple, efficient and easy to perform in calculating of shear forces and overturning moments of the large-upright industrial liquid storage tanks subjected to lateral earthquake loads. The results are verified with different codes (e.g. Eurocode8, API and AWWA-100...).

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Influence of Nonlinear Fluid Viscous Dampers on Seismic Response of RC Elevated Storage Tanks

Civil Engineering Journal ◽

10.28991/cej-2020-sp(emce)-09 ◽

2020 ◽

Vol 6 ◽

pp. 98-118

Author(s):

Manisha V. Waghmare ◽

Suhasini N. Madhekar ◽

Vasant A. Matsagar

Keyword(s):

Seismic Response ◽

Viscous Damper ◽

Storage Tanks ◽

Viscous Dampers ◽

Mass Model ◽

Ground Acceleration ◽

Fluid Viscous Dampers ◽

Liquid Storage ◽

Time Histories ◽

Real Earthquake

The numerical investigation on the seismic response of RC elevated liquid storage tanks installed with viscous dampers is presented. A discrete two-mass model for the liquid and multi-degree of freedom system for staging, installed with the dampers are developed for Reinforced Concrete (RC) elevated liquid storage tanks. The elevated tank is assessed for seismic response reduction when provided with Linear Viscous Damper (LVD) and Nonlinear Viscous Damper (NLVD), installed in the staging. The RC elevated liquid storage tanks are analyzed for two levels of liquid containment in the tank, 100% and 25% of the tank capacity. Three Configurations of placements of dampers viz. dampers at alternate levels (Configuration I and Configuration II) and dampers at all the panels of the staging of the tank (Configuration III) are considered. To study the effect of peak ground acceleration, eight real earthquake time histories with accelerations varying from 0.1 g to 0.93 g are considered. The nonlinearity in the viscous damper is modified by taking force proportional to various velocity exponents. It is found that the nonlinear viscous dampers with lower damping constant result in a comparable reduction in the response of RC elevated liquid storage tank, to that of linear viscous dampers with higher damping constant. A lower damping constant signifies compact the size of the damper. Doi: 10.28991/cej-2020-SP(EMCE)-09 Full Text: PDF

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Behavior of Unanchored Fluid-Filled Tanks Subjected to Ground Excitation

Journal of Applied Mechanics ◽

10.1115/1.3125844 ◽

1988 ◽

Vol 55 (3) ◽

pp. 654-659 ◽

Cited By ~ 20

Author(s):

S. Natsiavas ◽

C. D. Babcock

Keyword(s):

Experimental Data ◽

Dramatic Reduction ◽

Base Excitation ◽

Storage Tanks ◽

Response Frequency ◽

Qualitative And Quantitative ◽

Liquid Storage ◽

Beam Type ◽

Effective Beam ◽

Good Agreement

An analysis developed for the response of liquid storage tanks under horizontal base excitation is employed and numerical results are obtained for unanchored tanks. These results are compared and found to be in good agreement with experimental data. Base uplift is shown to cause a dramatic reduction in the effective beam-type stiffness of a tank, which in turn reduces the tank response frequency and changes the developed hydrodynamic loads significantly. Based on these results, an explanation is provided for some great qualitative and quantitative differences in the behavior of a tank, resulting from its base fixity condition alone.

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An Analytical Model for Unanchored Fluid-Filled Tanks Under Base Excitation

Journal of Applied Mechanics ◽

10.1115/1.3125843 ◽

1988 ◽

Vol 55 (3) ◽

pp. 648-653 ◽

Cited By ~ 25

Author(s):

S. Natsiavas

Keyword(s):

Ground Motion ◽

Bottom Plate ◽

Rigid Foundation ◽

Base Excitation ◽

Storage Tanks ◽

Cylindrical Tank ◽

Hydrodynamic Problem ◽

Liquid Storage ◽

Ground System ◽

Lift Off

A set of equations is derived describing the dynamic response of cylindrical liquid storage tanks under horizontal ground excitation. The structure consists of a flexible cylindrical tank with a roof and a bottom plate and rests on a flexible ground through a rigid foundation. Portion of the base of the tank may separate from and lift off the foundation during ground motion. The solution of the hydrodynamic problem is first found in closed form. Then, Hamilton’s principle is applied and the equations governing the behavior of the coupled fluid/structure/ground system are derived. During this procedure, the base uplifting is modeled by an appropriate rotational nonlinear spring placed between the base of the tank and the foundation.

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