• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.86-86
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• 2020

수리구조물에 관한 기존 연구들은 대부분 기능성과 안정성 측면에서 본체에 작용하는 유체력에 대한 안정성에 주안점을 두고 있다. 수리구조물 상·하류의 수위차에 기인한 기초지반내의 흐름 및 간극수압 변화는 하천 구조물의 안정성을 연구하는데 매우 중요하다. 해양에서는 파랑하중에 의한 과잉간극수압이 액상화를 발생시켜 해안구조물의 안정에 큰 영향을 미치는 것으로 보고되며, 이에 관련 연구들이 활발하게 진행되고 있다. 반면, 하천구조물 주변 지반의 흐름 및 간극수압 뿐 아니라, 액상화에 관한 연구는 아직 미진한 실정이다. 본 연구에서는 수리구조물 주변의 유동 및 와동 현상 뿐 아니라, 수위차에 따른 지반 내부 유동장과 간극수압에 관한 특성을 분석하기 위해 유체-구조물-지반 비선형 상호작용을 고려할 수 있는 수치수조를 새롭게 제안하였다. 그리고 제안하는 수치수조의 타당성 및 유효성을 검증하기 위해 기존 실험값과 비교·검토를 수행하였고, 그 결과는 거의 유사한 경향을 나타내었다. 또한 이 수치수조에 다양한 입사조건(상·하류 수위차)에 적용하여 유체-구조물-지반의 비선형동적상호간섭 해석을 수행하였다. 최종적으로 수치수조에서 측정한 구조물 주변의 유동, 와동, 수위로부터 수리특성을 논의하였다. 게다가 지반내의 흐름과 간극수압을 측정하여 상·하류 수위차가 수리구조물의 안정성에 미치는 영향을 분석할 수 있었다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.6
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• pp.383-390
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• 2020

Since the dynamic behaviors of liquid storage tanks on flexible soil are significantly influenced by the fluid-structure-soil interaction (FSSI), its effects must be rigorously considered for accurate earthquake analysis and seismic design of the storage system. In this study, dynamic analysis is performed for a rectangular liquid storage tank on flexible soil, and its dynamic characteristics are examined by rigorously considering the effects of FSSI. The hydrodynamic force and the interaction force between the structure and soil are evaluated using the finite-element approach. In the evaluations, mid-point integrated finite elements and viscous dampers are considered for energy radiation into the infinite soil. The effective earthquake force is then obtained from free-field analysis. It is thus demonstrated that the earthquake responses of the rectangular liquid storage tank on flexible soil are significantly influenced by the FSSI.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.3
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• pp.1-12
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• 2012

In this study, an analysis method for the earthquake response of an offshore wind turbine model is developed, considering the effects of the fluid-structure-soil interaction. The turbine is modeled as a tower with a lumped mass at the top of it. The tower is idealized as a tubular cantilever founded on flexible seabed. Substructure and Rayleigh-Ritz methods are used to derive the governing equation of a coupled structure-fluid-soil system incorporating interactions between the tower and sea water and between the foundation and the flexible seabed. The sea water is assumed to be a compressible but non-viscous ideal fluid. The impedance functions of a rigid footing in water-saturated soil strata are obtained from the Thin-Layer Method (TLM) and combined with the superstructure model. The developed method is applied to the earthquake response analysis of an offshore wind turbine model. The method is verified by comparing the results with reference solutions. The effects of several factors, such as the flexibility of the tower, the depth of the sea water, and the stiffness of the soil, are examined and discussed. The relative significance of the fluid-structure interaction over the soil-structure interaction is evaluated and vice versa.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.1
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• pp.45-53
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• 2020

Analytical and experimental studies show that the dynamic behavior of liquid storage tanks is significantly influenced by the fluid-structure interaction (FSI). The effects of FSI must be rigorously considered for accurate earthquake analysis and seismic design of liquid storage tanks. In this study, a dynamic analysis of a rectangular liquid storage tank subjected to bi-directional earthquake ground motions is performed and its dynamic characteristics are examined, with the effects of FSI rigorously considered. Hydrodynamic pressure is evaluated using the finite-element approach with acoustic elements and applied to the structure. The responses of the rectangular tank subjected to bi-directional earthquake ground motions are thus obtained. It can be observed that the incident angle of bi-directional horizontal ground motions has significant effects on the dynamic responses of the considered system. Therefore, the characteristics of the system must be considered in its seismic design and performance evaluation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.4
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• pp.319-327
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• 2017

In this study, characteristics of seismic behaviors of offshore wind turbine systems using concrete-suction-type supporting structures are investigated. Applying hydrodynamic pressure from the surrounding sea water and interaction forces from the underlying soil to the structural system which is composed of RNA, the tower, and the supporting structure, a governing equation of the system is derived and its earthquake responses are obtained. It can be observed from the analysis results that the responses are significantly influenced by soil-structure interaction because dynamic responses for higher natural vibration modes are increased due to the flexibility of soil. Therefore, the soil-structure interaction must be taken into consideration for accurate assessment of dynamic behaviors of offshore wind turbine systems using concrete-suction-type supporting structures.

• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.463-472
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• 1994

A method of stochastic response analysis of base-isolated fluid-filled pool structures subject to random ground excitations is studied. Fluid-structure interaction effects between the flexible walls and contained fluid are taken into account in the form of added mass matrix derived by FEM modeling of the contained fluid motion. The stationary ground excitation is represented by Modified Clough-Penzien spectral model and the nonstationary one is obtained by imposing an envelope function on the stationary one. The stationary and nonstationary response statistics of the two different isolation systems are obtained by solving the governing Lyapunov covariance matrix differential equations.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.132-137
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• 2001

This paper presents a method of seismic analysis for a 2-D fluid-structure-soil interaction systems. With this method, the fluid can be modeled by spurious free 4-node displacement-based fluid elements which use rotational penalty and mass projection technique in conjunction with the one point reduced integration scheme to remove the spurious zero energy modes. The structure and the near-field soil are discretized by the standard 2-D finite elements, while the unbounded far-field soil is represented by the dynamic infinite elements in the frequency domain. Since this method directly models the fluid-structure-soil interaction systems, it can be applied to the dynamic analysis of a 2-D liquid storage structure with complex geometry. Finally, results of seismic analyses are presented for a spent fuel storage tank embedded in a layered half-space and a massive concrete dam on a layered half-space.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.1
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• pp.41-46
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• 2005

The seismic response characteristics of a port structure were investigated by the earthquake analyses of the structure subjected to high-, low-frequency component, and Uljin earthquakes. In the Fluid-Structure-Soil Interaction(FSSI) analysis, the fluid is modeled by the 4-node quadrilateral element which is a modification of a structural plane element, and the port structure and foundation is modelled by the plane strain element. Since the present method directly models the fluid-structure-soil interaction system using finite element method, it can be easily applied to the dynamic analysis of a 2-D fluid-port-soil system with complex geometry. The results of the seismic coefficient. added mass, and FSSI methods are compared. The results showed that the earthquake with high frequency components more affects the seismic response of the structure than that of low frequency components.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.145-151
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• 2019

The fragility analyses for the partially filled horizontal cylindrical tank having a flexible wall were conducted to evaluate seismic performance. An equivalent simplified model with two lumped masses representing to impulsive and convective masses was used to represent the liquid storage system. This simplified model was validated by comparing its time history analysis results with the 3D FSI model results. The horizontal tank was analyzed under bi-directional excitations. Seismic fragility curves for the stability were developed in transverse and longitudinal directions. Fragility curves show that seismic damage for the horizontal storage system is more susceptible in the transverse direction.