• Journal of Korean Society of Steel Construction
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• v.16 no.6 s.73
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• pp.833-846
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• 2004

This study presents a non-prismatic beam element for modeling the elastic behavior of steel beams, which have the post-Northridge connections in steel moment frames. The elastic stiffness matrix, including the shear effects for non-prismatic members with reduced beam section (RBS) connection, is in closed form. A simplified approach is also suggested, which uses a prismatic beam element to model beams with the RBS connection. This method can estimate quiteexactly the maximum story drift ratios of frames with the RBS connection. The effects of reduced beam section connection on the elastic stiffness of steel moment frames were investigated. The selection of a proper model to account for deformations at the joint might have a more important role in estimating the maximum story drift ratios of frames with better accuracy than the RBS cutouts.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.629-636
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• 2011

It has been suggested that buildings designed for strong ground motions will also have improved resistance to air blast loads. As an initial attempt to quantify this behavior, the responses of a ten story steel building, designed for the 1994 building code, with lateral resistance provided by perimeter moment frames, is considered. An analytical model of the building is developed and the magnitude and distribution of blast loads on the structure are estimated using available computer software that is based on empirical methods. To obtain the relationship between pressure, time duration, and standoff distance, these programs are used to obtain an accurate model of the air blast loading. A hemispherical surface burst for various explosive weights and standoff distances is considered for generating the air blast loading and determining the structural response. Linear and nonlinear analyses are conducted for these loadings. Air blast demands on the structure are compared to current seismic guidelines. These studies present the displacement responses, story drifts, demand/capacity ratio and inelastic demands for this structure.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.3
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• pp.45-55
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• 2001

The purpose of this paper is to present the optimal design method of viscoelastic dampers and support brace stiffnesses. The dynamics of visco-elastic dampers and support braces connected in series is modeled by state equation. A constraint on maximum story drifts which are computed using RMS\`s of story drifts and peak factors is added to the optimization problem. The number of variables is reduced by including the constraint associated with the dynamic behavior of the structure in the procedure to compute the gradient of the inequality equation about constraint on the maximum story drifts. In the design example, it is confirmed that the design of dampers considering support brace stiffnesses is necessary when sufficient brace stiffnesses cannot be supplied. It is also found that unnecessary brace stiffnesses can be removed by adding brace stiffnesses to optimal design variables and that the increase of damper volumes to compensate for the variation of maximum story drifts is pretty small.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.2
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• pp.99-108
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• 2000

구조물의 능동제어 시스템에서 제어기 설계에 사용되는 구조계의 모델과 실구조계의 차이는 시스템의 성능저하 및 불안정성을 유발할 수 있다 이연구에서는 무시된 고차모우드와 같이 주파수영역에서 표현되는 비구조적 불확실성에 대하여 시스템의 안정성을 보장하도록 강인성을 가지는 LQG/LTR제어이론을 사용하여 구조물의 지진응답제어에 효과적으로 사용할 수 있는 제어기 설계방법을 제시한다 특히 고층건물이나 교탑과 같은 구조물의 지진응답 제어에 적용할 수 있도록 각층의 절대 가속도를 측정변수로 층간상대변위를 제어변수로 설정하여 최적제어기를 구성한다 El Centro 지진압력을 받는 6자유도 전단빌딩모델에 대하여 제어기를 설계하거 수치모사를 수행하여 제시한 제어기가 안정도-강인성을 가지고 지진응답제어에 효과적임을 보인다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.2
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• pp.35-42
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• 2021

In this study, a steel frame that realized the second floor of a structure was fabricated in referring to NFPA 13. In addition, a riser pipe system with groove joints was installed, and a seismic simulation test was performed using static cyclic loading. Cyclic loading tests on the maximum allowable side sway of seismic design standards for buildings in Korea were conducted using actuators to analyze the seismic behavior of the riser pipe system and major piping elements due to the deformation of the steel frame structure or the displacement-dominant behavior caused by the relative displacement between the structural members in the event of a seismic load. Moreover, the deformation angle of the riser pipe system was measured using an image measurement system because it is difficult to measure using the conventional sensors.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.435-441
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• 2003

본 논문에서는 Maximum Energy Dissipation Algorithm(MEDA) 사장교의 MR댐퍼제어에 적용하고자 한다 MR댐퍼의 제어를 위해서 여러 제어 이론들이 제안되었으나, 각각의 특성에도 불구하고 성능면에서는 큰 차이가 없다 MEDA는 Lyapunove 직접법을 바탕으로 군성되는 제어이론으로써, 15년전에 제안되었음에도 실제 토목구조물에는 적용된 바 없어 그 성능 및 장점이 제대로 검증되지 않았다. 따라서 본 논문에서는 벤치마크 사장교 수치예제를 통해서, MEDA의 토목구조물에의 적용성을 성능(performance)과 강인성(robustness) 측면에서 분석하려한다. 수치예제에서 다양한 지진에 대한 층간변위, 가속도, 그리고 상대변위의 각 제어기법에 의한 감소량은 벤치마크문제에 정의된 평가지수(evaluation criteria)를 사용하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.243-251
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• 2005

In the seismic design the pile foundation system of the buildings generally have been modeled to have a fixed end for its convenience and conservativeness. But it is necessary to consider the soil-structure interaction for more reliable design. In this study, the framed tube building and brace tube building with pile foundation system under earthquake were analyzed considering soil-structural interaction by 3 pile foundation modeling methods; fixed-end model, 6 springs model and p-y springs model. And 2 soil conditions were used in analysis. For each cases, displacements, drifts, maximum stress, periods and 1st mode mass participation ratios were compared.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.30-30
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• 2011

국내의 내진설계 기준은 1988년에 처음 도입되었으며, 최근 점차 강화되고 있는 실정이다. 공동주택에 주로 적용되는 전단벽식 구조시스템에서 증가된 지진력에 저항하기 위해서는 벽량과 철근이 증가하게 되어 공사비가 상승하게 된다. 이러한 단점을 보완하기 위한 제진설계의 필요성이 대두되고 있는 실정인데, 기존의 제진장치는 주로 가새형 또는 벽체형을 대부분이라 평면계획에 제약이 있다. 따라서 전단벽식 구조의 공동주택의 제진설계 시에는 우리나라와 같은 중 약진 지역에 적합하고 저렴한 비용으로 충분한 내진성능과 평면의 가변성을 확보할 수 있는 댐퍼의 선택이 필요하다. 본 연구의 목적은 기존의 가새형 및 벽체형 제진장치의 국내 공동주택 적용시의 문제점인 평면의 가변성 확보에 유리하고, 수동형 제진장치의 장점을 추구할 수 있는 마찰댐퍼를 삽입한 커플링보 제진시스템의 내진성능을 조사하는 것이다. 내진성능을 평가하기 위해서 실대형 커플링보 실험체를 계획하고 제작하였다. 실험체는 2개로 구성되어 있으며, 하나는 기존의 철근배근 상세를 갖는 철근콘크리트 커플링보 실험체와 커플링보에 마찰댐퍼가 삽입된 실험체이다. 횡하중에 대한 성능을 평가하기 위해서 유사정적 반복가력실험을 실시하였다. 엑츄에이터로부터 실험체 상보의 가력지그를 통해 하중이 전달되도록 하였으며, 가력은 최초 0.25%의 층간변형각부터 변위제어를 통해 목표 층간변형각인 1.5% 이상까지 진행되도록 하였다. 실험결과, 두 실험체의 이력곡선과 에너지 흡수능력을 평가하였다. RC 실험체는 핀칭현상이 관찰되었고, 가력이 진행됨에 따라 커플링보와 벽체에서의 균열이 확산되어 종국적으로 취성적인 커플링보의 전단파괴가 발생하였다. 마찰댐퍼를 삽입한 실험체는 계획된 마찰거동이 잘 발휘되어 목표 층간변형각인 1.5%까지 이선형거동이 잘 나타났다. 최대 내력은 RC 실험체가 3배 이상 크지만, 누적층간변형각에 따른 에너지 흡수능력은 마찰댐퍼 실험체가 2배 이상 우수한 결과를 보였으며, 커플링보 및 벽체에서의 균열이 매우 저감되었다.

• Journal of Korean Society of Steel Construction
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• v.23 no.5
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• pp.595-606
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• 2011

This study was conducted to investigate the seismic behavior of steel member resisting frames considering the relative stiffness of the connection and beams. Six-story steel moment frames were designed to study the seismic behavior. The connections were classified into Double Web-Angle connections (DWAs), Top- and Seat-angles with double Web-angles (TWSs), FEMA-Test Summary No. 28, Specimen ID: UCSD-6 (SAC), and Fully Restrained (FR). The rotational stiffness of the semi-rigid connections was estimated using the Three-Parameter Power Model adopted by Chen and Kishi. The relative stiffness, which is the ratio of the rotational stiffness of the connections to the stiffness of the beams, was used. Push-over, repeated loading, and time history analysis were performed for all the frames. The seismic behavior of each frame was analyzed with the story drift, plastic hinge rotation, and hysteretic energy distribution.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.429-436
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• 2014

This paper presents the seismic performance of a geometrically unsymmetrical reinforced concrete building considering torsional effect and material nonlinearity of concrete and steel. The reinforced concrete building is a structure for seismic performance evaluation in the SMART-2013 international benchmark program. Nonlinear constitutive models for concrete and steel were constructed, and their numerical performance was demonstrated by various local tests. Modal analysis showed that the first three natural frequencies and mode shapes were close to the experimental results from the SMART-2013 program. In the time history analysis for low-intensity seismic loadings, displacement and acceleration responses at sampling points were similar to the experimental results. In the end, nonlinear time history analysis was conducted for Northridge earthquake to predict the behavior of the reinforced concrete structure under high-intensity seismic loadings.