• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.429-432
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• 2009

본 논문에서는 현수교에 대하여 지반-구조물 상호작용을 고려한 해석을 수행하였다. 교량의 앵커리지와 기초를 부분구조법(Structure method)을 이용한 지반-구조물 상호작용(Soil-Structure Interaction) 해석프로그램 SASSI를 이용하여 구조물 저면에서의 지반 임피던스(Impedance)를 계산하고 이로부터 앵커리지 및 기초와 지반에 대응하는 강성, 질량, 그리고 감쇠를 가지는 집중 파라메터 모델을 구하였다. 그리고 현수교 유한요소 모델에 앵커리지 및 기초와 지반에 대한 집중 파라메터 모델을 연계하여 전체 교량에 대한 지반-구조물 시스템을 구성하고 시간영역에서의 지반 운동에 대한 동적해석을 수행하였다. 해석결과를 지반-구조물 상호작용을 고려하지 않은 경우와 고려한 경우를 비교하였고 파동전달효과를 고려한 경우와 고려하지 않은 경우를 비교함으로써 지반-구조물 상호작용의 영향을 살펴보았다.

• Journal of Korean Society of Steel Construction
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• v.8 no.3 s.28
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• pp.97-105
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• 1996

A Stochastic line source model is developed to simulate the seismic wave field generated during the rupture propagation process along a fault plane of which length is much larger than its width. The fault plane is assumed to consist of randomly distributed slip zones and barriers and each slip zone is modeled as a point source. By combining the newly developed source model with wave propagation analysis method in a layered 3-D visco-elastic half space, synthetic seismograms are obtained. The calculated accelerograms due to vertical dip slip and strike slip line sources are presented.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.1
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• pp.75-83
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• 2000

This paper deals with the application of two dimensional filtering technique for strain calculation using old and new geodetic data, and discusses the characteristics of general strain pattern in terms of seismic activity and tectonics. The mean rate of maximum shear strain is $0.12{\mu}/yr$. The mean direction of principal axes distribution of the compression is about $N80^{\circ}E$.

• Journal of the Korean Geotechnical Society
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• v.16 no.5
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• pp.157-168
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• 2000

토류구조물의 안정문제로는 장단기적으로 정적인 경우와 동적인 경우, 그리고 지반의 동적 거동특성, 흙의 강도저하 등을 미리 파악하여 기술적인 대처를 할 필요가 있을 것이다. 본 연구에서는 실내 모형 실험을 통하여 구조물의 배면에 토성이 다른 일반모래, 표준모래, 점성토를 뒷채움하여 다짐없이 강사만 하고, 룰러다짐, 진동다짐을 하여 토피의 수평 진동거리를 길게, 짧게 그리고 중간으로 하여 강성벽체에 작요？는 수평토압에 대한 정적, 동적 특성을 규명하는 것이다. 모형 실험장치로는 실험대, 토조, 토압측정장치, 진동하중 발생장치, 진동측정장치, 강사기, 롤러 등을 설치하여 거리에 따른 병진운동으로 가속도와 수평토압, 수평토압계수, 전체토압, 토압의 작용점, 지진토압증분 증을 구하여, 실험결과와 기존 이론결과, 그리고 유한요소 해석결과와 비교 고찰하였다.

• Economic and Environmental Geology
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• v.55 no.5
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• pp.541-550
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• 2022

A pre-existing landform is created by weathering and erosion along the bedrock fault and the weak zone. A neotectonic landform is formed by neotectonic movements such as earthquakes, volcanoes, and Quaternary faults. It is difficult to clearly distinguish the landform in the actual field because the influence of the tectonic activity in the Korean Peninsula is relatively small, and the magnitude of surface processes (e.g., erosion and weathering) is intense. Thus, to better understand the impact of tectonic activity and distinguish between pre-existing landforms and neotectonic landforms, it is necessary to understand the development process of pre-existing landforms depending on the bedrock characteristics. This study used a two-dimensional numerical landscape evolution model (LEM) to study the spatio-temporal development of landscape according to the different erodibility under the same factors of climate and the uplift rate. We used hill-slope indices (i.e., relief, mean elevation, and slope) and channels (i.e., longitudinal profile, normalized channel steepness index, and stream order) to distinguish the difference according to different bedrocks. As a result of the analysis, the terrain with high erosion potential shows low mean elevation, gentle slope, low stream order, and channel steepness index. However, the value of the landscape with low erosion potential differs from that with high erodibility. In addition, a knickpoint came out at the boundary of the bedrock. When researching the actual topography, the location around the border of difference in bedrock has only been considered a pre-existing factor. This study suggested that differences in bedrock and various topographic indices should be comprehensively considered to classify pre-existing and active tectonic topography.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.4
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• pp.353-362
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• 2020

Korea was recognized as a relatively safe area for earthquake. However, due to considerable damage to facilities caused by the earthquake in Gyeongju and Pohang, interest in the maintenance and repair of structures is increasing. So interest in vibration damping technology applicable to existing structures is also increasing. However, vibration damping technology has a problem in that its usability is reduced due to damage of the damping device when a strong earthquake occurs. Recently, in order to solve such a problem, study is being conducted to apply a superelastic shape memory alloys (SSMA) capable of recentering bracing. Therefore, in this study, nonlinear dynamic analysis is performed to evaluate the seismic performance of the buckling-restrained braced frame (BRBF) applied SSMA to bracing.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.3
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• pp.85-92
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• 2015

Response spectra of a building are made with a SDOF system taking into account a first mode shape, even though higher modes may affect on the dynamic responses of a high-rise building. A soft soil layer under a building also affects on the responses of a building. In this study, seismic responses of a MDOF system were investigated to examine the effects of higher modes on the response of a tall building by comparing them with those of a SDOF system including the kinematic interaction effect. Study was performed using a pseudo 3D finite element program with seven bedrock earthquake records downloaded from the PEER database. Effects of higher modes on the seismic responses of a tall building were investigated for base shear force and base moment of a MDOF system including story shear forces and story moments. Study results show that higher modes of a MDOF system contribute to a reduction of base shear force up to 1/4-1/5 of KBC and base moment. The effect of higher modes is more significant on the base shear force than on the base moment. Maximum story shear force and moment occurred at the top part of a building rather than at a base in the cases of tall buildings differently from short buildings, and higher modes of a tall building affected on the base forces making them almost constant at the base. A soft soil layer also affects some on the base shear force of a high-rise building independently on the soft soil type, but a soft soil effect is prominent on the base moment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.1
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• pp.37-45
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• 1990

An analytical procedure is proposed for the seismic analysis of a soil-structure interaction system with besemat uplift, including the effects of concurrent vertical seismic ground motion, nonlinear distribution of bearing soil pressure under the basemat, and 3-dimensional behavior of the system. The soil-structure interaction system is assumed to have rectangular-shaped basemat on elastic half-space. Nonlinearity of soil spring constants and soil damping coefficients induced by the base mat uplift is modeled by considering not only the reduction of contact area between soil and structure but also the effects of rigid body rotational motion of the superstructure, and the shift in the point of action of the resultant reaction on the basemat. Throught various parametric studies. it has been confirmed that the seismic responses of the superstructure reduce notably while response at the basemat increases considerably. The results also show that the effects of concurrent vertical ground motion. nonlinear soil pressure distribution under basemat, and 3-dimensional behavior of the system shall be included in uplift analysis in order to obtain the correct structural responses.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.1 s.41
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• pp.51-59
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• 2005

Magnetorheological(MR) dampers are one of the most promising semi active control devices, because they have advantages such as small power requirement, reliability, and low price to manufacture. To reduce the responses of structures with MR dampers, a control system including power supply, controller, and sensors is required. However, when a mount of MR dampers are used to a large?scale civil structure such as cable stayed bridges, the control system becomes complex. Therefore, it is not easy to install and maintain the MR damper based control system. To resolve above difficulties, This paper proposes a smart passive system that consists of a MR damper and an electromagnetic induction(EMI) system. According to the Faraday’s law of induction, EMI system that is attached to the MR damper produces electric energy. The produced energy is supplied to the MR damper. Thus, the MR damper with EMI system does not require any power at all. Furthermore, the induced electric energy is proportional to external loads like earthquakes, which means the MR damper with EMI system is adaptable to external loads without any controller and corresponding sensors. Therefore, it is easy to build up and maintain the proposed smart passive system.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.6
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• pp.11-18
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• 2011

Accurate modal identification analysis is required to reasonably perform a seismic qualification of safety-related electric equipment installed in nuclear power plants (NPPs). This study evaluates a variation of the modal properties of an electric equipment cabinet structure in NPPs according to the excitation levels. For the study, an actual electric equipment cabinet was selected as a specimen and was dynamically tested by using a portable exciter in accordance with the level of input vibration energy. Tests were classified into two sets: with-door cases, and without-door cases. Frequency response functions were computed from the signals of the acceleration responses and input motions measured from the vibration tests. A polynomial curve fitting algorithm was used to extract the modal properties from the frequency response functions. This study reviews the variation of the modal properties according to the variation of the excitation levels. The results of the study show that the modal frequencies and the modal dampings of the object specimen varies nonlinearly according to the excitation level of the test motion. Attaching the door increases the modal damping of the cabinet.