• Earthquakes and Structures
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• v.12 no.5
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• pp.583-589
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• 2017

In this study, result of a field investigation of railway traffic-induced vibrations is provided to examine acceptability levels of ground vibration and to evaluate the serviceability of a liquid-storage tank. Free field attenuation of the amplitudes as a function of distance is derived by six accelerometers and compared with a well-known half-space Bornitz's analytical solution which considers the loss of the amplitude of waves due to geometrical damping and material damping of Rayleigh. Bornitz's solution tends to overlap vertical free field vibration compared with in-situ measured records. The vibrations of the liquid-storage tank were compared with the USA, Federal Transportation Railroad Administration (FTA) criteria for acceptable ground-borne vibrations and with the criteria in DIN 4150-3 German standard. Comparing the thresholds stated in DIN 4150-3, absolute peak particle velocities are within the safe limits, however according to FTA velocity level at the top of the water tank exceeds the allowable limits. Furthermore, it is intended to indicate experimentally the effect of the kinematic interaction caused by the foundation of the structure on the free-field vibrations.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.1
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• pp.23-34
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• 1998

A dynamic fluid-structure-soil interaction analysis method is developed to investigate the effects of translational and/or rocking motions on the seismic response of flexible rectangular liquid storage tanks founded on the deformable ground. The governing equation for the dynamics of 3-D rectangular tanks subjected to the translational and/or rocking motion is abtained by applying Rayleigh-Ritz method. The dynamic stiffness matrices of a rigid rectangular foundation resting on the surface of a stratum overlaid bedrock are calculated by hyperelement method. The seismic responses of 3-D flexible tank model founded on the deformable ground is calculated by combining the governing equation for the fluid-tank system with the dynamic stiffness matrix of th rigid surface foundation.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.1
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• pp.21-32
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• 2024

This study performed the seismic response analysis of an LNG storage tank supported by a disconnected piled raft foundation (DPRF) with a load transfer platform (LTP). For this purpose, a precise analytical model with simultaneous consideration of Fluid-Structure Interaction (FSI) and Soil-Structure Interaction (SSI) was used. The effect of the LTP characteristics (thickness, stiffness) of the DPRF system on the seismic response of the superstructure (inner and outer tanks) and piles was analyzed. The analytical results were compared with the response of the piled raft foundation (PRF) system. The following conclusions can be drawn from the numerical results: (1) The DPRF system has a smaller bending moment and axial force at the head of the pile than the PRF system, even if the thickness and stiffness of the LTP change; (2) The DPRF system has a slight stiffness of the LTP and the superstructure member force can increase with increasing thickness. This is because as the stiffness of the LTP decreases and the thickness increases, the natural frequency of the LTP becomes closer to the natural frequency of the superstructure, which may affect the response of the superstructure. Therefore, when applying the DPRF system, it is recommended that the sensitivity analysis of the seismic response to the thickness and stiffness of the LTP must be performed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.230-236
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• 2018

Earthquakes over 5.0 on the Richter scale have recently occurred in Korea, which has led to interest in the seismic safety of structures. If a water storage facility is damaged by an earthquake, the water could leak, and the insufficient water would make fire suppression difficult. Therefore, a water storage facility should satisfy safety requirements for earthquakes. In this study, the seismic performance of a water tank was improved by installing a lead rubber bearing between the foundation and the tank. It designed the lead rubber bearing available to the existed concrete foundation. ANSYS was used for modeling to consider the interaction between the fluid and structure of the tank and the hydrostatic and hydrodynamic pressure using four seismic waves. In the case of hydrostatic pressure at 2.5 water level, full level, the same stress appeared irrespective of whether the seismic isolation was installed. When hydrostatic pressure and hydrodynamic pressures are applied at the same time, the seismic-isolated water tank showed less seismic force, and the damping ratio was lower than that of general seismic isolation. This occurred because the weight of the water tank is much smaller than the stiffness of the seismic isolation. The result is expected to be used for further research on seismic capacity evaluation for water tanks.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.3
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• pp.441-449
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• 2019

Recently, interest in the seismic safety of structures is rising in South Korea due to the occurrences of earthquakes of 5.0 or greater magnitudes such as Gyeongju earthquake (September 2016) and Pohang earthquake (November 2017). In particular, the importance of living facilities that cause human injuries and property losses is more emphasized. Representative living facilities include gas and oil storage facilities and water tanks. In this study, the seismic performance of liquid storage tanks is improved by applying the lead rubber bearing, which is a seismic isolation method. The lead rubber bearing was designed considering the foundation of liquid storage tanks, and the general properties of the lead rubber bearing were verified through compression and shear tests using fabricated specimens. Furthermore, the behaviors of liquid storage tanks according to seismic and non-seismic isolations were analyzed through durability test, shaking table test and finite element analysis using ANSYS.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.81-92
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• 2018

Recently, the use of natural gas has steadily increased due to its economical advantage and increased demand of clean energy uses. Accordingly, construction of LNG storage tanks is also increased. Secure of the stability of LNG tanks storage requires high technology as natural gas is stored in a liquid state for efficiency of storage. When a cryogenic LNG fluid leaks on ground due to a defect in LNG tank, damage is expected to be significant. Many researchers evaluated the critical and negative effects of LNG leakage, but there is limited research on the effect of cryogenic fluid leakage on the ground supporting LNG tanks. Therefore, in this study, the freezing expansion of the ground during cryogenic LNG fluid leakage was evaluated considering various outflow situations and ground conditions. The LNG leakage scenarios were simulated based on numerical analyses results varying the surcharge load, temperature boundary conditions, and soil types including freeze-sensitive soil. Consequently, short and long term ground temperature variations after LNG leakage were evaluated and the resulting ground behavior including vertical displacement behavior and porosity were analyzed.

• The Journal of Engineering Geology
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• v.33 no.1
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• pp.151-167
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• 2023

This study compares the revised method in loose saturated sandy ground where the LNG storage tank will be installed with an evaluation method by one-dimensional effective stress analysis using the UBC3D-PLM model. Various laboratory and field tests were conducted to establish the parameters necessary for evaluation. The revised liquefaction evaluation method using the seismic response analysis result and N value from standard penetration testing evaluated the possibility of liquefaction as high, but assessment using effective stress analysis, which can consider various liquefaction resistance factors, found the site to be somewhat stable against liquefaction. One-dimensional finite element analysis using UBC3D-PLM modeling facilitated easier assessment of stability against liquefaction than the other methods and minimized the area required for reinforcement against liquefaction. In addition, it is expected that two-and three-dimensional numerical analysis considering the foundation of the LNG storage tank can identify the seismic design and behavior when liquefaction occurs.

• Geomechanics and Engineering
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• v.13 no.6
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• pp.929-946
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• 2017

Composite foundation treated with compaction piles can eliminate collapsibility and improve the bearing capacity of foundation in loess area. However, the large number of piles in the composite foundation leads to difficulties in the analysis of such type of engineering works. This paper proposes two simplified methods to quantify the stability of composite foundation treated with a large number of compaction piles. The first method is based on the principle of making the area replacement ratios of the simplified model as the same time as the practical engineering situation. Then, discrete piles arranged in a triangular shape can be simplified in the model where the annular piles and compacted soil are arranged alternately. The second method implements equivalent continuous treatment in the pile-soil area and makes the whole treated region equivalent to a type of composite material. Both methods have been verified using treated foundation of an oil storage tank. The results have shown that the differences in the settlement values obtained from the water filled test in the field and those calculated by the two simplified methods are negligible. Using stability analysis, the difference ratios of the static and dynamic safety factors of the composite foundation treated with compaction piles calculated by these two simplified methods are found to be 3.56% and 5.32%, respectively. At the same time, both static and dynamic safety factors are larger than the general safety factor, which should be greater than or equal to 2.0 according to the provisions in civil engineering. This indicates that after being treated with compaction piles, the bearing capacity of the composite foundation is effectively improved and the foundation has enough safety reserve.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.257-266
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• 1999

This paper presents a method of seismic analysis for a cylindrical liquid storage structure on/in horizontally layered half.space considering the effects of the interior fluid and exterior soil medium in the frequency domain. To capture the essence of fluid-structure-soil interaction effects effectively, a mixed finite element with two-field (u, p) approximation is employed to model the compressive inviscid fluid, while the structure and soil medium are presented by the 3-D axisymmetric finite elements and dynamic infinite elements. The present FE-based method can be applied to the system with complex geometry of fluid region as well as with inhomogeneous near-field soil medium, since it can directly model both the fluid and the soil. For the purpose of verification, dominant peak frequencies in transfer functions for horizontal motions of cylindrical fluid storage tanks with rigid massless foundation on a homogeneous viscoelastic half.space are compared with those by two different added mass approaches for the fluid motion. The comparison indicates that the Present FE-based methodology gives accurate solution for the fluid-structure-soil interaction problem. Finally, as a demonstration of versatility of the present study, a seismic analysis for a real-scale LNG storage tank embedded in layered half.space is carried out, and its member forces along the height of the structure are compared with those by an added mass approach developed by the present writers.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.607-618
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• 2022

This study involves the development of a Hwangto permeable block for rainwater storage tanks. The permeable products that form continuous voids between Hwangto binders and aggregates are fine milled slag powder, which is an industrial by-product generated during the production of Hwangto and iron, and ferro nickel slag. The properties of Hwangto permeable blocks were studied using recycled resource aggregates. The target quality is based on KSF 2394. The Hwangto permeable block for a rainwater storage tank is made of water-permeable material, and the permeability of the Hwangto permeable block itself is 0.1mm/sec or higher, with a physical performance of over 5.0MPa in flexural strength and over 20.0MPa in compressive strength. The physical properties of Hwangto permeable block for rainwater storage tanks were researched and developed. In order to prevent flooding due to heavy rain in summer and the urban heat island phenomenon due to depletion of ground water, continuous pores are formed in the block to secure a permeability function to prevent rainwater from accumulating in the pavement of the floor, and to prevent slippage for comfortable and safe storage.