• Steel and Composite Structures
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• 제50권6호
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• pp.643-658
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• 2024

The main aim of this study is to quantify the code seismic design coefficients of the RCS system, which consisted of reinforced concrete columns and steel beams, based on the FEMA P-695 methodology. The underlying intention is to evaluate the seismic performance of the RCS system at the system level rather than the connection level. A set of 24 archetype buildings with a various number of stories, beam span lengths, gravity load levels, and seismic load levels are selected and designed based on the prevailing code requirements. Nonlinear analytical models are developed and validated by experimental tests. The pushover and response history dynamic analyses are conducted to evaluate the required data in the performance quantification process. The results show that the design coefficients suggested by the code are acceptable. However, the level of conservatism is very high. Thus, it is possible to use a larger R-factor in the design process or make some relaxations in the design requirements related to this structural system.

• 한국강구조학회 논문집
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• 제22권1호
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• pp.75-85
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• 2010

최근 초고층 건물에 구조적인 측면을 고려한 Freeform Structure라는 개념이 등장하고 있다. 이 형태는 Diagrid, Cantilevered, Tilted로 대변될 수 있는데 특히 다이아 그리드 시스템은 횡저항에 하중의 흐름을 가새 프레임을 따라 분산시킴으로써 효율적인 거동을 보이기 때문에 그만큼 부재를 경량화시킬 수가 있다. 그러나 Diagrid 구조시스템의 내진성능 평가를 위한 반응수정계수에 대한 신뢰성 있는 자료가 없기 때문에 우수한 내진성능이 예상됨에도 불구하고 기타구조 등으로 설계되고 있다. 본 연구에서는 실대형 실험을 통해 Diagrid 구조의 반응수정계수를 실험적으로 규명하고자 한다.

• Earthquakes and Structures
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• 제5권6호
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• pp.657-678
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• 2013

For economical earthquake resistant design of cable-stayed bridge tower, the use of energy dissipation systems for the earthquake protection of steel structures represents an alternative seismic design method where the tower structure could be constructed to dissipate a large amount of earthquake input energy through inelastic deformations in certain positions, which could be easily retrofitted after damage. The design of energy dissipation systems for bridges could be achieved as the result of two conflicting requirements: no damage under serviceability limit state load condition and maximum dissipation under ultimate limit state load condition. A new concept for cable-stayed bridge tower seismic design that incorporates sacrificial link scheme of low yield point steel horizontal beam is introduced to enable the tower frame structure to remain elastic under large seismic excitation. A nonlinear dynamic analysis for the tower model with the proposed energy dissipation systems is carried out and compared to the response obtained for the tower with its original configuration. The improvement in seismic performance of the tower with supplemental passive energy dissipation system has been measured in terms of the reduction achieved in different response quantities. Obtained results show that the proposed energy dissipation system of low yield point steel seismic link could strongly enhance the seismic performance of the tower structure where the tower and the overall bridge demands are significantly reduced. Low yield point steel seismic link effectively reduces the damage of main structural members under earthquake loading as seismic link yield level decreases due their exceptional behavior as well as its ability to undergo early plastic deformations achieving the concentration of inelastic deformation at tower horizontal beam.

• Steel and Composite Structures
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• 제19권5호
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• pp.1167-1184
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• 2015

Despite considerable life casualty and financial loss resulting from past earthquakes, many existing steel buildings are still seismically vulnerable as they have no lateral resistance or at least need some sort of retrofitting. Passive control methods with decreasing seismic demand and increasing ductility reduce rate of vulnerability of structures against earthquakes. One of the most effective and practical passive control methods is to use a shear panel system working as a ductile fuse in the structure. The shear Panel System, SPS, is located vertically between apex of two chevron braces and the flange of the floor beam. Seismic energy is highly dissipated through shear yielding of shear panel web while other elements of the structure remain almost elastic. In this paper, lateral behavior and related benefits of this system with narrow-flange link beams is experimentally investigated in chevron braced simple steel frames. For this purpose, five specimens with IPE (narrow-flange I section) shear panels were examined. All of the specimens showed high ductility and dissipated almost all input energy imposed to the structure. For example, maximum SPS shear distortion of 0.128-0.156 rad, overall ductility of 5.3-7.2, response modification factor of 7.1-11.2, and finally maximum equivalent viscous damping ratio of 35.5-40.2% in the last loading cycle corresponding to an average damping ratio of 26.7-30.6% were obtained. It was also shown that the beam, columns and braces remained elastic as expected. Considering this fact, by just changing the probably damaged shear panel pieces after earthquake, the structure can still be continuously used as another benefit of this proposed retrofitting system without the need to change the floor beam.

• Structural Engineering and Mechanics
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• 제73권2호
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• pp.153-165
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• 2020

The effect of soil foundation plays active role in optimum design of steel space frames when included. However, its influence on design can be calculated after a long iterative procedure. So it requires longer computer time and more computational effort if it is done properly. The main purpose of this study is to investigate how these effects can be calculated in more practical way in a shorter time. The effects of semi-rigid column bases are taken into account in optimum design of steel space frames. This study is carried out by using JAYA algorithm which is a novel and practical method based on a single revision equation. The displacement, stress and geometric size constraints are considered in the optimum design. A computer program is coded in MATLAB to achieve corporation with SAP2000-OAPI (Open Application Programming Interface) for optimum solutions. Four different steel space frames including soil structure interaction taken from literature are investigated according to different semi-rigidly supported models depending on different rotational stiffness values. And the results obtained from analyses are compared with the results available in reference studies. The results of the study show that semi-rigidly supported systems in the range of appropriate rotational stiffness values offer practical solutions in a very short time. And close agreement is obtained with the studies on optimum design of steel space frames including soil effect underneath.

• 대한건축학회논문집:구조계
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• 제35권10호
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• pp.171-180
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• 2019

In Korea, the seismic design of non-structural elements was interested by Earthquake of the 2016 Gyeong-ju and 2017 Po-hang. Among the non-structural elements, the ceiling system with steel panel used in Po-hang station showed failure examples of non-seismic design ceiling. In this study, the seismic performance of suspended ceiling with steel-panel, such as those used in Po-hang Station, was evaluated by shaking table tests. The shaking table tests were performed in accordance with the ICC-ES AC156 standard with floor acceleration being applied horizontally in one direction using a $3.3{\times}3.3m^2$ frame. The ceiling system consists of steel-panels, carrying channels, main and cross T-bars, and anti-falling clips. The anti-falling clip prevents the steel panel falling completely. The shaking table test confirmed that the damage at the previous stage had a direct impact on the damage state at the next stage. Through the shaking table test, the damage state of the T-bar type steel-panel suspended ceiling system was defined.

• 한국전산구조공학회논문집
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• 제24권6호
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• pp.629-636
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• 2011

최근 들어 여러 테러에 의한 폭발사건에서 유발된 위험상황에서 보듯이 폭발에 의한 인명피해나 시설물의 손상은 우리가 고려하는 재해수준을 넘는 비참한 결과를 항상 수반한다. 하지만 폭발에 대한 구조물의 설계는 그 연구나 대책이 상당히 미비한 실정이다. 이에 미국건물설계기준(UBC94)을 바탕으로 내진설계(Welded Moment Resistant Frame)된 10층 건물의 폭발에 대한 해석적 모델을 제공하고자 한다. 현재 폭발하중의 정량적인 결과는 미국 육군(U.S.Department of Army)에서 개발된 경험적 방법에 기반을 둔 프로그램을 통해 폭간거리에 따른 하중의 크기와 분포를 알 수 있다. 본 연구에 사용된 폭원의 성격은 반구형 표면 폭발(Hemispherical Surface Burst)의 경우를 사용하였으며, 또한 선형 및 비선형 시간 이력해석을 통해 건물의 변위, 상대변위, 요구/수행비 및 비선형 거동에 대한 해석적 결과를 제공하였다. 또한 현재 사용되고 있는 내진기준(FEMA356)에 적용하여 소성힌지의 거동을 통해 폭발에 대한 건물의 성능수준을 예상하였다.

• 한국지진공학회논문집
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• 제7권2호
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• pp.49-58
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• 2003

본 연구에서는 구조가 간단하고 경제적이며, 보수유지 면에서 능동형 진동제어 장치로서 매우 유리한 장점을 가지고 있는 선형모터 댐퍼(LMD : linear motor damper)를 개발하여 유니슨 기술연구소에 설치된 대형 철골구조물에 적용하였다. 개발된 LMD는 1,500kg의 가동질량을 갖고 있으며, 최대 $\pm$250mm의 변위로 움직일 수 있다. 제어 대상 시험구조물의 최저차 2개 진동형만을 가지는 축소모델을 사용하여 H$_{\infty}$ 제어로직을 설계하였다. 일련의 성능 검증시험을 통해 시험 구조물의 1, 2차 진동형에 대해 가속도 레벨이 약 l0dB 감소함을 확인하였다. 본 연구를 통해 개발된 LMD가 풍 및 지진하중을 받는 구조물의 진동제어용 제진장치로서 가능성이 있음을 확인하였다.

• 한국강구조학회 논문집
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• 제18권2호
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• pp.225-237
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• 2006

김 등(2005a, b)의 연구를 확장시켜 시스템 좌굴 고유치해석법을 이용한 유효좌굴길이 산정법과 2차 탄성해석기법을 이용한 2차모멘트를 이용하여 축력과 휨모멘트를 받는 라멘구조의 보-기둥부재에 대한 개선된 좌굴설계법을 제안한다. 이를 위하여 먼저 국내도로교설계기준, AISC-LRFD, SRC의 각 설계기준에 제시된 내하력 기준식을 이용하여 응력-변형율 관계를 유도하고, 이를 이용한 탄성 및 비탄성 좌굴 고유치해석을 이용한 유효좌굴길이 산정법을 고찰한다. 또한 라멘구조에 대하여 AISC-LRFD에서 제시하고 있는 좌굴 안정성 검토식과 본 연구에서 제시하는 안정성 검토식을 해석예제를 통하여 비교, 검토를 행한다.

• Steel and Composite Structures
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• 제35권2호
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• pp.187-197
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• 2020

Ground motion records are commonly used for fragility curves (FCs) developing utilized in seismic loss estimating analysis for earthquake prone zones. These records could be 'real', say the recorded acceleration time series or 'simulated' records consistent with the regional seismicity and produced by use of alternative simulation methods. This study has focused on fragility curves developing for masonry buildings through computational 'simulated' ground motion records while evaluating the properness of these fragilities compared to the curves generated by the use of 'real' records. Assessing the dynamic responses of structures, nonlinear computational time history analyses through the equivalent single degree of freedom systems have been implemented on OpenSees platform. Accordingly, computational structural analyses of multi-story 3D frame structures with different stiffening members considering soil interaction have been carried out with finite element software according to (1992) Earthquake East-West component. The obtained results have been compared to each frame regarding soil interaction. Conclusion and recommendations with the discuss of obtaining findings are presented.