• 한국터널지하공간학회 논문집
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• 제20권5호
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• pp.757-772
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• 2018

최근 경주 포항 등 대도시에서 지진이 발생하고 이에 각 분야에서의 내진해석 연구가 활발히 진행되고 있다. 하지만 대부분의 기존 내진해석은 지상구조물과 지반을 따로 다루었기 때문에 지반과 구조물의 완전한 상호 동적거동에 대한 연구가 부족한 실정이다. 따라서 본 연구에서는 건물만 고려하는 지하구조물 고정단 모델과 건물과 지반을 함께 고려하는 연속체 모델을 각각 적용하기 위해 MIDAS GEN 및 MIDAS GTS NX를 이용하여 민감도 분석을 수행하고 SSI를 고려한 동적해석의 타당성을 살펴보았다. 연구 결과, 대부분의 조건에서 지하구조물 고정단 모델이 연속체 모델보다 초고층 건물의 최대 순수 수평변위를 더 작게, 휨응력을 더 크게, 또한, 취약부의 범위는 더 작게 산출하는 것으로 나타났다. 따라서 내진해석 시 지반-구조물 상호작용을 고려한 연속체 모델을 사용하는 것이 보다 타당할 것으로 판단된다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.335-342
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• 1998

A soil-structure interaction (SSI) experiment is being conducted in a seismically active region in Hualien, Taiwan. To obtain earthquake data for quantifying SSI effects and providing a basis to benchmark analysis methods, a 1/4-th scale cylindrical concrete containment model similar in shape to that of a nuclear power plant containment was constructed in the field where both the containment model and its surrounding soil, surface and sub-surface, are extensively instrumented to record earthquake data. In between September 1993 and May 1996, fifteen earthquakes with Richter magnitudes ranging from 4.2 to 6.2 were recorded. The recorded data were analyzed to provide information on the response characteristics of the Hualien soil-structure system, the SSI effects and the ground motion characteristics. The ground response data were analyzed for their variations with depth, with distance from the model structure, and at the same depths along downhole arrays. Variations of soil stiffness and soil-structure system frequencies were also evaluated against maximum ground motion. In addition, the site soil properties were derived based on correlation analysis of the recorded data and then correlated with those from the geotechnical investigation data.

• Coupled systems mechanics
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• 제11권5호
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• pp.373-387
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• 2022

In this paper,soil-structure interaction effects on the seismic response of multistory frame structure on raft foundation are numerically analyzed. The foundation soil profile is assumed to consists of a clay layer of variable thicknessresting on bedrock. Amodified plane-strain numerical model isformed in the software Plaxis, and both free vibration analysis, and earthquake analysis for a selected ground motion accelerogram are performed. The behavior of the structure is assumed to be linear elastic with Rayleigh viscous damping included. The behavior of the clay layer is modeled with a Hardening soil model with small strain stiffness. The computed results in terms of fundamental period and structural horizontal displacementsfor the case of fixed base and for different thicknesses of clay layer are presented, compared, and discussed.

• 대한토목학회논문집
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• 제32권3C호
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• pp.85-94
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• 2012

본 논문은 액상화 지반에서의 지반-지하 중공구조물 상호작용에 따른 구조물의 rocking현상을 조사하기 위해서 수행한 원심모형실험에 관하여 서술하고 있다. 지진이 발생하였을 때 지반이 강한 진동에 노출되면 상대밀도가 낮은 느슨한 모래지반에서는 액상화가 발생하며, 액상화된 지반보다 작은 단위중량을 가진 지하 중공구조물은 부상한다. 지하 중공구조물이 부상하는 동안에 구조물의 동적 거동과 구조물의 부상량에 대한 원지반의 영향을 평가하기 위하여 원지반의 상대밀도를 다르게 모델지반을 제작하였고, 아크릴 박스를 이용하여 트랜치를 제작하여 모형실험을 수행하였다. 실험결과, 액상화된 원지반의 측방유동 및 주변지반의 전단변형에 의해 야기되는 지하 중공구조물의 rocking현상이 지하 중공구조물의 부상량의 규모에 크게 기여하는 것으로 나타났다.

• Earthquakes and Structures
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• 제7권1호
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• pp.83-99
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• 2014

This study is devoted to estimate higher-mode effects for multi-story structures with considering soil-structure interaction subjected to decomposed parts of near-fault ground motions. The soil beneath the super-structure is simulated based on the Cone model concept. Two-dimensional structural models of 5, 15, and 25-story shear buildings are idealized by using nonlinear stick models. The ratio of base shears for the soil-MDOF structure system to those obtained from the equivalent soil-SDOF structure system is selected as an estimator to quantify the higher-mode effects. The results demonstrate that the trend of higher-mode effects is regular for pulse component and has a descending variation with respect to the pulse period, whereas an erratic pattern is obtained for high-frequency component. Moreover, the effect of pulse component on higher modes is more significant than high-frequency part for very short-period pulses and as the pulse period increases this phenomenon becomes vice-versa. SSI mechanism increases the higher-mode effects for both pulse and high-frequency components and slenderizing the super-structure amplifies such effects. Furthermore, for low story ductility ranges, increasing nonlinearity level leads to intensify the higher-mode effects; however, for high story ductility, such effects mitigates.

• 한국지반공학회논문집
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• 제22권4호
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• pp.105-111
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• 2006

본 연구에서는 먼저 지표면을 비롯하여 구조물 곳곳에 가속도계가 설치된 깊은 직접기초 구조물 2개를 선정하였다. 이어서 구조물에 기록된 실지진 데이터를 사용하여 주파수 영역에서 Transmissibility 함수를 사용하는 기법으로 기초 위치에서와 자유지표면에서의 지반운동 사이의 차이를 산정하였고 실지진기록을 사용하여 산정된 이 변환함수를 기존의 간편식과 비교하여 검증하였다. 비록 강성 기초저면, 연직으로 전파되는 지반운동을 가정하는 간편식의 전제조건은 실제 조건과 차이가 있지만, 그럼에도 불구하고 실지진기록으로부터 산정된 변환함수와 매우 양호한 유사성을 보여주므로 간편식을 설계실무에서 사용할 수 있을 것으로 판단된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.101-110
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• 2002

This article summarises the traditional method of soil-structure interaction based on the modulus of subgrade reaction and shows its weakness. In order to avoid these weakness, a new soil-structure interaction model is proposed. This model considers the soil as a set of connected springs which enables interaction between springs. Its use is as simple as the traditional model but allows to define the soil properties independently from the structural properties and the loading conditions. Thus, the definition of the modulus of subgrade reaction is unnecessary as each component is defined by its own modulii (Young's modulus and shear modulus). The non-linear soil behaviour for the shear stress versus distortion is also incorporated in the model. This feature allows to pinpoint the arching effect in the ground and shows how the stresses concentrate on stiff materials. Based on these principles, three dimensional program has been developed in order to solve the difficult problem of soil improvement by inclusions (stiff or soft). Also the possibility to take into account a flexible mat and/or a subgrade layer has been implemented. Equations used in the model are developed and a parametric study of the necessary data used in the program is presented. In particular, the Westergaard modulus notion and the arching effect are analysed.

• Earthquakes and Structures
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• 제27권1호
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• pp.41-55
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• 2024

There are obvious differences between the characteristics of offshore ground motion and onshore ground motion in current studies, and factors such as water layer and site conditions have great influence on the characteristics of offshore ground motion. In addition, unlike seismic response analysis of offshore superstructures such as sea-crossing bridges, tunnels are affected by offshore soil constraints, so it is necessary to consider the dynamic interaction between structure and offshore soil layer. Therefore, a seismic response analysis model considering the seawater, soil layer and tunnel structure coupling is established. Firstly, the measured offshore and different soil layers onshore ground records are input respectively, and the difference of seismic response under different types of ground motions is analyzed. Then, the models of different site conditions were input into the measured onshore bedrock strong ground motion records to study the influence of seawater layer and silt soft soil layer on the seabed and tunnel structure. The results show that the overall seismic response between the seabed and the tunnel structure is more significant when the offshore ground motion is input. The seawater layer can suppression the vertical seismic response of seabed and tunnel structure, while the slit soft soil layer can amplify the horizontal seismic response. The results will help to promote seismic wave selection of marine structures and provide reference for improving the accuracy of seismic design of immersed tunnels.

• Structural Engineering and Mechanics
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• 제43권5호
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• pp.637-655
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• 2012

In this study, stochastic responses of a cable-stayed bridge subjected to the spatially varying earthquake ground motion are investigated by the finite element method taking into account soil-structure interaction (SSI) effects. The considered bridge in the analysis is Quincy Bay-view Bridge built on the Mississippi River in between 1983-1987 in Illinois, USA. The bridge is composed of two H-shaped concrete towers, double plane fan type cables and a composite concrete-steel girder deck. In order to determine the stochastic response of the bridge, a two-dimensional lumped masses model is considered. Incoherence, wave-passage and site response effects are taken into account for the spatially varying earthquake ground motion. Depending on variation in the earthquake motion, the response values of the cable-stayed bridge supported on firm, medium and soft foundation soil are obtained, separately. The effects of SSI on the stochastic response of the cable-stayed bridge are also investigated including foundation as a rigidly capped vertical pile groups. In this approach, piles closely grouped together beneath the towers are viewed as a single equivalent upright beam. The soil-pile interaction is linearly idealized as an upright beam on Winkler foundation model which is commonly used to study the response of single piles. A sufficient number of springs on the beam should be used along the length of the piles. The springs near the surface are usually the most important to characterize the response of the piles surrounded by the soil; thus a closer spacing may be used in that region. However, in generally springs are evenly spaced at about half the diameter of the pile. The results of the stochastic analysis with and without the SSI are compared each other while the bridge is under the sway of the spatially varying earthquake ground motion. Specifically, in case of rigid towers and soft soil condition, it is pointed out that the SSI should be significantly taken into account for the design of such bridges.

• 한국지진공학회논문집
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• 제22권6호
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• pp.333-343
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• 2018

In this paper, we study the existing results of the structure-soil-structure interaction (SSSI) effect on seismic responses of structures and summarize important parameters. The parameters considered in this study are a combination of buildings in the power block of a nuclear power plant, the characteristics of earthquake ground motions and its direction, and the characteristics embedded under the ground. Based on these parameters, the seismic analysis model of the structures in the power block of the nuclear power plant is developed and the structure-soil-structure interaction analyses are performed to analyze the influence of the parameters on the seismic response. For all analyses, the soil-structure interaction (SSI) analysis program CNU-KIESSI, which was developed to enable large-sized seismic analysis, is used. In addition, the SSI analyses is performed on individual structures and the results are compared with the SSSI analysis results. Finally, the influence of the parameters on the seismic response of the structure due to the SSSI effect is reviewed through comparison of the analysis results.