scholarly journals Effect of Double-Side Curved Baffle on Reducing Sloshing in Tanks under Surge and Pitch Excitations

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Aimeng Zhu ◽  
Mi-An Xue ◽  
Xiaoli Yuan ◽  
Feng Zhang ◽  
Wei Zhang
Keyword(s):  
Effective Stress ◽  
Laboratory Experiments ◽  
Hydrodynamic Pressure ◽  
Structural Safety ◽  
Tank Wall ◽  
Motion Platform ◽  
Liquid Storage ◽  
Wave Elevation ◽  
Wave Heights ◽  
Free Surface Wave

Sloshing is associated with the structural safety of liquid storage vessel. Installing the baffles inside the containers would be beneficial for the mitigating the damage due to the severe sloshing. In this study, an innovative type of double-side curved baffle was proposed to evaluate its effect on reducing sloshing in a rectangular tank under surge and pitch excitation. For comparison with conventional baffles, effects of the vertical baffle and the T-type baffle on mitigating sloshing were also studied experimentally and numerically by analyzing the free surface wave elevation as well as the hydrodynamic pressure on the tank wall. The effective stress at the double-side curved baffle along the height direction of the baffle is much smaller than that at the T-type baffle although they have the same mitigation effect on sloshing wave heights. The sloshing-induced effective stress on the double-side curved baffles was analyzed by varying their radian. Findings show that the effective stress on the baffle tends to decrease with the increase in the radian. The velocity field was presented to observe effect of the baffles on sloshing with the aid of ADINA and laboratory experiments conducted on a hexapod motion platform.

Generalized SDOF system for dynamic analysis of concrete rectangular liquid storage tanks: effect of tank parameters on response

2010 ◽  
Vol 37 (2) ◽  
pp. 262-272 ◽  
Author(s):  
J. Z. Chen ◽  
M. R. Kianoush
Keyword(s):  
Dynamic Response ◽  
Natural Frequencies ◽  
Hydrodynamic Pressure ◽  
Characteristic Parameter ◽  
Added Mass ◽  
Tank Wall ◽  
Storage Tanks ◽  
Effective Height ◽  
Sdof System ◽  
Liquid Storage

This paper presents the results of parametric studies on the seismic response of concrete rectangular liquid storage tanks using the generalized single-degree-of-freedom (SDOF) system. The effects of height of liquid and width of tank on the dynamic response of liquid storage tanks are investigated. The liquid level varies from the empty condition to a full tank. Also, instead of the commonly used ratio of width of tank to liquid height, Lx/HL, the ratio of width of tank to full height of the tank wall, Lx/Hw, is used as a characteristic parameter of tanks to study the effect of tank size on the dynamic response. The trends of added mass of liquid, effective height, and natural frequencies for different sizes of tanks are established. The values of the added mass of liquid due to impulsive hydrodynamic pressure and the effective height in the relationship with the ratios Lx/Hw and HL/Hw are determined and can be used in the seismic design of liquid storage tanks. Since the natural frequencies of liquid-containing structures are within a band of frequencies between that of a full tank and that of an empty tank, the recommended frequency to be used in the design of the tank wall is the frequency that causes the maximum dynamic response .

scholarly journals Generalized SDOF system for dynamic analysis of concrete rectangular liquid storage tanks

2021 ◽  
Author(s):  
Jun Zheng Chen
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Seismic Analysis ◽  
Design Procedure ◽  
Hydrodynamic Pressure ◽  
Added Mass ◽  
Tank Wall ◽  
Storage Tanks ◽  
Sdof System ◽  
Liquid Storage

Liquid storage tanks are essential facilities in lifeline and industrial systems. To ensure liquid tightness, serviceability is the prime design concern for these structures. While there have been major studies on the behavior of steel tanks, little attention has been paid to the behavior of rectangular concrete tanks. In this study, the dynamic response of concrete rectangular liquid storage tanks is investigated. In the current design practice, the response of liquid and tank structure is determined based on rigid tank wall and the lumped mass approach. However, the results of analysis show that the flexibility of tank wall increases the hydrodynamic pressures as compared to the rigid wall assumption. Also, recent studies show that the lumped added mass method leads to overly conservative results in terms of base shear and base moment. In addition, in spite of advanced analysis techniques available for dynamic analysis of liquid storage tanks such as finite element method and sequential coupling analysis procedure, there is a need to develop a simplified analysis method for practical applications. In this thesis, a simplified method using the generalized single degree of freedom (SDOF) system is proposed for seismic analysis of concrete rectangular liquid containing structures (LCS). Only the impulsive hydrodynamic pressure is considered. In the proposed method, the consistent mass approach and the effect of flexibility of tank wall on hydrodynamic pressures are considered. Different analytical methods are used to verify the proposed model in this study. The comparison of results based on the current design practice, the analytical-finite element models and full finite element model using ANSYS® shows that the proposed method is fairly accurate which can be used in the structural design of liquid containing structures. Parametric studies on seismic analysis of concrete rectangular LCS using the generalized SDOF system are carried out. Five prescribed vibration shape functions representing the first mode shape of fluid structure interaction system are used to study the effect of flexibility of tank wall and boundary conditions. The effect of flexibility of tank wall, the amplitude of hydrodynamic pressure, the added mass of liquid due to hydrodynamic pressure, the effective heights for liquid containing system and the effect of higher modes on dynamic response of LCS are investigated. In addition, the effect of variable size of tanks and liquid depth are studied. The contribution of higher modes to the dynamic response of LCS is included in the proposed model. A design procedure based on the structural model using the generalized SDOF system is proposed in this study. Design charts and tables for the added mass of liquid due to impulsive hydrodynamic pressure and the corresponding effective heights are presented. The proposed design procedure can be used for engineering design applications.

scholarly journals Generalized SDOF system for dynamic analysis of concrete rectangular liquid storage tanks

2021 ◽  
Author(s):  
Jun Zheng Chen
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Seismic Analysis ◽  
Design Procedure ◽  
Hydrodynamic Pressure ◽  
Added Mass ◽  
Tank Wall ◽  
Storage Tanks ◽  
Sdof System ◽  
Liquid Storage

Liquid storage tanks are essential facilities in lifeline and industrial systems. To ensure liquid tightness, serviceability is the prime design concern for these structures. While there have been major studies on the behavior of steel tanks, little attention has been paid to the behavior of rectangular concrete tanks. In this study, the dynamic response of concrete rectangular liquid storage tanks is investigated. In the current design practice, the response of liquid and tank structure is determined based on rigid tank wall and the lumped mass approach. However, the results of analysis show that the flexibility of tank wall increases the hydrodynamic pressures as compared to the rigid wall assumption. Also, recent studies show that the lumped added mass method leads to overly conservative results in terms of base shear and base moment. In addition, in spite of advanced analysis techniques available for dynamic analysis of liquid storage tanks such as finite element method and sequential coupling analysis procedure, there is a need to develop a simplified analysis method for practical applications. In this thesis, a simplified method using the generalized single degree of freedom (SDOF) system is proposed for seismic analysis of concrete rectangular liquid containing structures (LCS). Only the impulsive hydrodynamic pressure is considered. In the proposed method, the consistent mass approach and the effect of flexibility of tank wall on hydrodynamic pressures are considered. Different analytical methods are used to verify the proposed model in this study. The comparison of results based on the current design practice, the analytical-finite element models and full finite element model using ANSYS® shows that the proposed method is fairly accurate which can be used in the structural design of liquid containing structures. Parametric studies on seismic analysis of concrete rectangular LCS using the generalized SDOF system are carried out. Five prescribed vibration shape functions representing the first mode shape of fluid structure interaction system are used to study the effect of flexibility of tank wall and boundary conditions. The effect of flexibility of tank wall, the amplitude of hydrodynamic pressure, the added mass of liquid due to hydrodynamic pressure, the effective heights for liquid containing system and the effect of higher modes on dynamic response of LCS are investigated. In addition, the effect of variable size of tanks and liquid depth are studied. The contribution of higher modes to the dynamic response of LCS is included in the proposed model. A design procedure based on the structural model using the generalized SDOF system is proposed in this study. Design charts and tables for the added mass of liquid due to impulsive hydrodynamic pressure and the corresponding effective heights are presented. The proposed design procedure can be used for engineering design applications.

Mitigation of liquid sloshing in a rectangular tank due to slotted porous screen

2020 ◽  
Vol 234 (3) ◽  
pp. 686-698
Author(s):  
Sunny Kumar Poguluri ◽  
Il-Hyoung Cho
Keyword(s):  
Free Surface ◽  
Numerical Technique ◽  
Liquid Sloshing ◽  
Tank Wall ◽  
Air Entrapment ◽  
Jet Formation ◽  
Induced Motion ◽  
Free Surface Wave ◽  
Nonlinear Free Surface ◽  
Porous Screen

Liquid sloshing inside a tank with a slotted porous screen at the center is studied based on numerical and experimental methods. Slotted screens with three different porosities (0.0964, 0.1968 and 0.3022) for two submergence depths of 1 and 2 cm have been considered. One of the main advantages of the slotted screens is that the resonance frequency of the sloshing tank can be altered and the sloshing-induced motion/load can be suppressed by energy dissipation across the porous screen. The complexities of slotted screens equipped in a sloshing tank are accompanied by wave breaking, jet formation and liquid fragmentations which are commonly seen phenomena across the porous screen. These violent free surface behaviors in a tank are studied based on numerical simulations using the incompressible turbulent model and compared with the experiments. For the numerical sloshing tank with porous screen, free surface elevation and pressure at the tank wall are in good agreement with the experimental results. The adopted numerical technique will be able to capture the nonlinear free surface wave profile, air entrapment and jet formation across the screen in agreement with the experiments. For the fully submerged screen, the lowest resonance period shifted slightly to higher values. The sloshing tank equipped with porous screen of 0.1968 for the fully submerged screen predicted lower values of the amplification factor and pressure at the tank wall compared to other cases.

Multiphase Fluid Dynamics in Storage Tanks of Varying Geometry

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Obai Kargbo ◽  
Mi-An Xue ◽  
Jinhai Zheng
Keyword(s):  
Dynamic Pressure ◽  
Numerical Approach ◽  
Offshore Platforms ◽  
Storage Tanks ◽  
Fluid Sloshing ◽  
Hydrodynamic Response ◽  
Wave Heights ◽  
Free Surface Wave ◽  
Multiphase Fluid ◽  
Liquid Natural Gas

Abstract Sloshing control is key in the offshore storage and transportation of petroleum and other liquid phased products such as liquid natural gas (LNG). It is of interest in the enhancement of the structural stability of offshore platforms and floating production storage and offloading units. This work presents a numerical approach in the study and analysis of the effect of storage tank configurations on the hydrodynamic response of a multiphase-layered fluid undergoing sloshing. The study showed that tank configurations had an effect on the internal and free surface wave heights of the multiphase fluid sloshing in the tank, as well as on the dynamic pressure intensity being exerted on the tank walls, with some configurations exhibiting comparatively greater sloshing wave and pressure damping.

Model Experiments of Floating Side-by-Side Barges

2019 ◽  
Author(s):  
Kie Hian Chua ◽  
Pedro Cardozo de Mello ◽  
Kazuo Nishimoto ◽  
Yoo Sang Choo
Keyword(s):  
Numerical Models ◽  
Wave Excitation ◽  
Flow Models ◽  
Model Experiments ◽  
Dissipative Effects ◽  
Wave Elevation ◽  
Wave Heights ◽  
Wave Conditions ◽  
Incident Waves ◽  
Gap Width

Abstract The interaction between two floating vessels has been a subject of much study in recent years due to its relevance to floating liquefied natural gas (FLNG) developments. The safety and operability of these facilities are directly influenced by the wave elevation in the gap between the two vessels as well as the relative motions between the vessels. In the industry, it is common practice to use potential flow models to calculate free-surface responses under various wave conditions. Given that these numerical models are inviscid, calibration of additional damping terms are usually carried out using model tests to in order to account for the viscous dissipation on the gap hydrodynamics. However, it is known that the dissipative effects of viscosity may be nonlinear and thus, model test data obtained using one set of wave conditions may not be suitable for use in another scenario. In this paper, model experiments of two identical side-by-side barges of 280m (length) × 46m (breadth) × 16.5m (draught) under various wave excitation are described. The experiments considered a range of parameters such as gap width, wave heights, periods and wave directions. The results obtained for each set of these parameters are discussed and compared between the two types of incident waves (regular and irregular).

Seismic design forces for cylindrical tanks on ground

1985 ◽  
Vol 12 (1) ◽  
pp. 12-23
Author(s):  
W. K. Tso ◽  
A. Ghobarah ◽  
S. K. Yee
Keyword(s):  
Radius Ratio ◽  
Hydrodynamic Effect ◽  
Tank Wall ◽  
Base Shear ◽  
Ground Acceleration ◽  
Liquid Storage ◽  
Wall Flexibility ◽  
Flexibility Effect ◽  
Predicted Values ◽  
Cylindrical Tanks

A study is made on the hydrodynamic effect caused by seismic ground motions on the design of cylindrical on-ground liquid-storage tanks. The current techniques for determining the design base shear and overturning moment of the tank are reviewed, first treating the tank wall as rigid and then including the wall flexibility effect. By means of examples, these calculations are compared with those suggested by the National Building Code of Canada (NBCC). In addition, theoretically predicted values are compared with experimental data.It was found that in the case of tanks of high height to radius ratio and small wall thickness to radius ratio, the interaction of the fluid and wall flexibility can cause responses as high as two to three times those calculated based on rigid tank wall assumptions. The range of tank geometries under which the tank can be considered rigid is given. It is shown that the NBCC formula to establish seismic loads for tanks on ground is in general conservative, provided the acceleration ratio in the NBCC formulae takes on the value of maximum peak ground acceleration of the site. Key words: seismic, earthquake, hydrodynamic force, response, cylindrical tanks, design code.

Effects of Base Uplifting on the Seismic Response of Unanchored Liquid Storage Tanks

2012 ◽  
Author(s):  
Maria Vathi ◽  
Spyros A. Karamanos
Keyword(s):  
Seismic Response ◽  
Pushover Analysis ◽  
Hydrodynamic Pressure ◽  
Base Plate ◽  
Seismic Loading ◽  
Storage Tanks ◽  
Liquid Storage ◽  
Detailed Simulation ◽  
Steel Tank ◽  
Static Pushover Analysis

Unanchored liquid storage tanks under strong earthquake loading tend to uplift. In the present study, the effects of base uplifting on the seismic response of unanchored tanks are presented with emphasis on elephant’s foot buckling, base plate strength and shell-to-base connection capacity. Towards this purpose, base uplifting mechanics is analyzed through a detailed simulation of the tank using non-linear finite elements, and a static pushover analysis is conducted that considers the hydrodynamic pressure distribution due to seismic loading on the tank wall and the base plate. The uplifting provisions from EN 1998-4 and API 650 Appendix E standards are briefly described. Numerical results for a typical 27.8-meter-diameter steel tank are compared with the above design provisions.

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