• 한국지진공학회논문집
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• 제18권4호
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• pp.201-212
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• 2014

The plastic hinge region of RC pier ensures its nonlinear behavior during strong earthquake events. It is assumed that the piers secure sufficient strength and ductility in order to prevent the collapse of the bridge during strong earthquake. However, the presence of a lap-splice of longitudinal bars in the plastic hinge region may lead to the occurrence of early bond failure in the lap-splice zone and result in significant loss of the seismic performance. The current regulations for seismic performance evaluation limit the ultimate strain and displacement ductility considering the eventual presence of lap-splice, but do not consider the lap-splice length. In this study, seismic performance test and analysis are performed according to the cross-sectional size and the lap-splice length in the case of longitudinal bars with lap-splice located in the plastic hinge region of existing RC bridge columns with circular cross-section. The seismic behavioral characteristics of the piers are also analyzed. Based upon the results, this paper presents a more reasonable seismic performance evaluation method considering the lap-splice length and the cross-sectional size of the column.

• 한국지진공학회논문집
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• 제16권2호
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• pp.1-13
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• 2012

본 연구에서는 에너지 소산형 감쇠기가 설치된 철근콘크리트 구조물의 지진응답 저감효과를 확률적으로 평가하기 위하여 지진취약도 함수를 도출하였다. 가속도민감 영역과 속도민감 영역에 속하는 대표 고유주기를 갖는 비선형 단자유도 시스템으로 모델링된 철근콘크리트 구조물을 대상으로 강도와 강성의 불확실성을 고려하였다. 원구조물에 다양한 강성과 감쇠를 갖는 변위의존형 감쇠기를 부가하여 비선형시간이력해석을 수행하였으며, 해석결과의 통계를 바탕으로 로그정규분포 형태의 지진취약도 함수를 도출하였다. 원구조물의 종류별로 감쇠기의 설계변수에 따른 지진취약도 함수의 변화를 검토하고 이를 통해 손상확률의 저감효과를 분석하였다.

• 한국지반신소재학회논문집
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• 제19권1호
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• pp.55-63
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• 2020

본 연구에서는 다층으로 구성된 깊은 토사지반 내 박스구조물에 대하여 지진하중이 작용할 때 동적거동 특성을 규명하기 위하여 진동대를 이용한 축소모형시험과 유효응력을 고려한 내진해석을 수행하였다. 입력지진파는 장주기파(Hachinohe), 단주기파(Ofunato)와 인공지진파 및 최근 경주 및 포항지역에서 발생한 실지진파 등 5개의 지진파를 사용하여 하부지반에서 작용시켰다. 모형실험 및 수치해석 분석결과, 지진하중 작용시 박스구조물에 발생하는 변위는 연직방향이 수평방향에 비해 크게 발생하였으며, 기초지반 하부의 과잉간극수압 증가가 변위를 유발하는 것으로 확인하였다. 또한, 실지진파에 비해 인공지진파 작용시 지반 및 지중구조물의 동적거동이 크게 나타났다.

• 한국공간구조학회논문집
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• 제18권1호
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• pp.109-116
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• 2018

As the number of high-rise buildings increases, a mid-story isolation system has been proposed for high-rise buildings. Due to structural problems, an appropriate isolation layer displacement is required for an isolation system. In this study, the mid-story isolation system was designed and the seismic response of the structure was investigated by varying the yield strength and the horizontal stiffness of the seismic isolation system. To do this, a model with an isolation layer at the bottom of $15^{th}$ floor of a 20-story building was used as an example structure. Kobe(1995) and Nihonkai-Chubu(1983) earthquake are used as earthquake excitations. The yield strength and the horizontal stiffness of the seismic isolation system were varied to determine the seismic displacement and the story drift ratio of the structure. Based on the analytical results, as the yield strength and horizontal stiffness increase, the displacement of the isolation layer decreases. The story drift ratio decreases and then increases. The displacement of the isolation layer and the story drift ratio are inversely proportional. Increasing the displacement of the isolation layer to reduce the story drift ratio can cause the structure to become unstable. Therefore, an engineer should choose the appropriate yield strength and horizontal stiffness in consideration of the safety and efficiency of the structure when a mid-story isolation system for a high-rise building is designed.

• 한국산업융합학회 논문집
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• 제10권4호
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• pp.255-262
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• 2007

The main purpose of this study is to figure out of seismic structural behaviour of Gukrakjeon of Bongjung-Temple which is the oldest wooden architecture in Korea, and to evaluate in engineering aspect of seismic records. The non-lineal analysis is essential for accurate evaluation of wooden architecture in seismic behaviour. Based on the experimental test with applying cycle forces in joint specimens is focusing on not only to prove the structural characteristics, but also to evaluate damping ratio, As the result of this test, damping ratio is affected not the joint methods but the frame variations. The average damping ratio was 26%.

• 한국산학기술학회논문지
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• 제11권2호
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• pp.666-674
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• 2010

개착식 구조물이나 교량 구조물과 같은 도시철도 시설물을 대상으로 시행한 내진성능 예비평가체계는 도시철도 시설물이 지녀야하는 특성을 고려하지 못하는 문제점이 있다. 특히 교량 구조물의 경우에는 도로교의 내진성능 예비평가체계를 그대로 적용하여 사용하고 있어 도시철도 교량 구조물에 적용하기에는 비현실적인 평가 항목들이 존재한다. 그리고 각 시설물에 대한 예비평가 항목들을 산정할 때 적절한 근거가 없어 평가 결과의 신뢰성을 확보하지 못하고 있는 실정이다. 따라서 본 연구에서는 기존 내진성능 예비평가 체계의 문제점을 분석하고 수정(개정) 안을 제시한다.

• 한국구조물진단유지관리공학회 논문집
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• 제28권1호
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• pp.1-11
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• 2024

이 논문의 목적은 붕괴방지수준의 지진력을 적용한 콘크리트 댐 피어부 동적해석 시 합리적인 댐 축방향 지진하중 재하 방법, 내하력 평가 방법 등에 대한 적용방안을 제시하는 것이다. 이를 위하여 콘크리트 댐 피어부를 대상 시설로 선정하여 다양한 위어부 폭을 적용한 동적해석을 통해 위어부 댐 축방향 동적거동 특성을 분석하고 'U.S. Army Corps, 2007'제시하는 RC수력구조물 평가기법을 적용하여 내하력 평가를 수행하였다. 연구결과 피어부 댐 축방향 지진력 적용 시 위어부 댐 축방향은 강체거동으로 가정하는 것이 보다 현실적이고 'U.S. Army Corps, 2007'에서 제시하는 모멘트와 전단에 대한 내하력 검토방법이 합리적인 것으로 판단되므로 현행 평가방법의 개선이 필요한 것으로 결과가 도출되었다. 연구 결과 개선사항을 적용할 경우 CLE를 적용한 현행 내진성능평가 방법보다 합리적인 평가결과를 도출하는 효과가 있을 것이다. 피어부에 발생하는 비틀림 모멘트에 대해서는 향후 추가적인 연구가 필요한 것으로 판단된다.

• 한국지반환경공학회 논문집
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• 제22권7호
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• pp.5-12
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• 2021

The reliable seismic stability evaluation of the natural slopes and geotechnical structures has become a critical factor of the design. Pseudo-static or permanent displacement methods are typically employed to evaluate the seismic slope performance. In both methods, the effect of input ground motion on the sliding surface is ignored, and failure surface from the limit equilibrium method is used. For the assessment of the seismic sensitivity of failure surface, two-dimensional non-linear finite element analyses are performed. The performance of the finite element model was validated against centrifuge measurements. A parametric study with a range of input ground motion was performed, and numerical results were used to assess the influence of ground motion characteristics on the sliding surface. Based on the results, it is demonstrated that the characteristics of input ground motion have a significant influence on the location of the seismically induce failure surface. In addition to dynamic analysis, pseudo-static analyses were performed to evaluate the discrepancy. It is observed that sliding surfaces developed from pseudo-static and dynamic analyses are different. The location of the failure surface change with the amplitude and T_m of motion. Therefore, it is recommended to determine failure surfaces from dynamic analysis

• Earthquakes and Structures
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• 제9권2호
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• pp.339-352
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• 2015

Ancient masonry towers constitute a relevant part of the cultural heritage of humanity. Their earthquake protection is a topic of great concern among researchers due to the strong damage suffered by these brittle and massive structures through the history. The identification of the seismic behavior and failure of towers under seismic loading is complex. This strongly depends on many factors such as soil characteristics, geometry, mechanical properties of masonry and heavy mass, as well as the earthquake frequency content. A deep understanding of these aspects is the key for the correct seismic vulnerability evaluation of towers and to design the most suitable retrofitting measure. Recent tendencies on the seismic retrofitting of historical structures by means of prestressing are related to the use of smart materials. The most famous cases of application of prestressing in towers were discussed. Compared to horizontal prestressing, vertical post-tensioning is aimed at improving the seismic behavior of towers by reducing damage with the application of an overall distribution of compressive stresses at key locations.

• Steel and Composite Structures
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• 제21권6호
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• pp.1369-1388
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• 2016

This study is an effort to clearly recognize the seismic damages occurred in strap-braced cold formed steel frames. In order to serve this purpose, a detailed investigation was conducted on 9 full scale strap-braced CFS walls and the required data were derived from the results of the experiments. As a consequence, quantitative and qualitative damage indices have been proposed in three seismic performance levels. Moreover, in order to assess seismic performance of the strap-braced CFS frames, a total of 8 models categorized into three types are utilized. Based on the experimental results, structural characteristics are calculated and all frames have been modeled as single degree of freedom systems. Incremental dynamic analysis using OPENSEES software is utilized to calculate seismic demand of the strap-braced CFS walls. Finally, fragility curves are calculated based on three damage limit states proposed by this paper. The results showed that the use of cladding and other elements, which contribute positively to the lateral stiffness and strength, increase the efficiency of strap-braced CFS walls in seismic events.