• Wind and Structures
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• 제4권1호
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• pp.63-72
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• 2001

This paper presents results of a study on wind loads and wind induced dynamic response of bridge jointed twin-towered buildings. Utilizing the high-frequency force balance technique, the drag and moment coefficients measured in wind tunnel tests, and the maximum acceleration rms values on the top floor of towers, are analyzed to examine the influence of building's plan shapes and of intervals between towers. The alongwind, acrosswind and torsional modal force spectra are investigated for generic bridge jointed twin-towered building models which cover twin squares, twin rhombuses, twin triangles, twin triangles with sharp corners cut off, twin rectangles and individual rectangle with the same outline aspect ratio as the twin rectangles. The analysis of the statistical correlation among three components of the aerodynamic force corroborated that the correlation between acrosswind and torsional forces is significant for bridge jointed twin-towered buildings.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.675-680
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• 2004

In this study, a turbine simuiator is designed and manufactured to investigate the transient response of an actual turbine. The rotor mass and bearing stiffness is reduced to 1/140 of its actual turbine. The dynamic characteristics of turbine simulator are similar to those of the actual turbine. The turbine simulator is excited by an electro-magnetic type exciter in the form of half sine wave. Duration time is con☞oiled by Sms, 10ms, and Isms, and maximum acceleration is applied by 3g. Foundation excitation test is performed in stationary condition and rotating condition(6000rpm). The test results can be used to verify the validif of the theoretical afproach for transient analysis of actual turbine.

• 한국전산구조공학회논문집
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• 제30권6호
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• pp.523-530
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• 2017

본 연구에서는 역량스펙트럼법을 이용해 얻어진 구조물의 성능점을 확률적으로 평가하는 방법을 제시하였다. ATC-40에 따라 역량스펙트럼법을 이용하여 4층 1경간 철골구조물의 성능점을 산정하였다. 요구스펙트럼을 이용하여 구조물의 성능한계를 초과하는지 여부를 분석하기 위해 구조부재의 소성변형각으로부터 정의되는 구조물의 성능한계에 대해 한계변위를 도출하였다. 또한 설계응답스펙트럼과 유사한 응답스펙트럼을 가지는 인공지진파 30개를 선정하여 스펙트럼 가속도에 따른 각 성능한계의 초과여부를 통해 fragility curve를 도출하였다. 관측된 초과확률을 이용하여 fragility curve를 도출하기 위해 maximum likelihood method를 사용하였다. 각 성능한계점에 대응하는 설계응답스펙트럼의 응답가속도값에서 성능한계점을 초과할 확률은 존재하는 것으로 확인되었다. 본 방식은 구조물의 성능점에 대해 지진파의 불확실성을 고려한 확률적 평가가 가능하고, 시간증분해석이 필요하지 않아 해석시간을 상당부분 단축시킬 수 있다는 장점이 있다.

• 한국지진공학회논문집
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• 제10권4호
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• pp.55-66
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• 2006

본 연구에서는 강성골격곡선으로부터 산정한 구조물의 초기 탄성진동주기 $T_1$와 응답스트럼으로부터 산정한 비선형 유사가속도 $A_{1y}/g$ 및 연성비 ${\mu}$를 사용하여, 반복적인 계산과정 없이 복합구조물의 내진성능을 평가하는 비선형직접스펙트럼법(NDSM)을 고려한다. 다양한 지진과 복합구조물에 대한 NDSM의 신뢰성과 실용성을 비선형시각이력해석(NRHA) 결과와 비교 검토하였다. 본 연구의 결론은 다음과 같다. (1) NDSM은 강성골격곡선으로부터 기본진동주기와 비선형 항복강도를 구하면, 비선형 응답스펙트럼으로부터 직접적으로 구조물의 비선형 최대응답을 산정할 수 있는 실용적인 방법으로 사료된다. (2) NDSM의 응답을 정산해와 비교한 결과, 대부분의 모델이 단순평균의 관점에서 전체 해석모델 중 3/4이 약 20% 이하의 오차를 나타내었고, 일반적으로 비선형시각이력해석의 응답보다 크게 산정되는 것으로 나타났다.

• 한국구조물진단유지관리공학회 논문집
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• 제22권5호
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• pp.23-30
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• 2018

최근 들어 건물의 내진 및 내풍 성능을 향상시키기 위하여 감쇠구조에 대한 관심이 높아지고 있다. 감쇠장치 중 저렴한 비용과 높은 에너지소산능력을 발휘하며, 설치와 유지관리가 용이하다는 장점이 있어 강재이력형 감쇠장치를 이용한 수동형 감쇠구조시스템이 널리 사용되고 있다. 본 논문에서는 라멘구조 또는 무량판 구조에 적합한 계단 설치형 카고메 감쇠시스템(SKDS)을 제안하고자 하며, 제안된 감쇠시스템의 지진응답 개선효과에 대하여 해석적으로 검토하고자 한다. 비선형 동적해석결과 최대응답변위, 최대응답가속도 및 밑면전단력 감소로 살펴볼 때 내진구조와 비교하여 더 향상된 거동이 기대된다는 점에서 SKDS의 효과를 확인할 수 있었다.

• Earthquakes and Structures
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• 제23권1호
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• pp.23-34
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• 2022

This paper presents experimental studies on reinforced concrete moment resisting frames that have engineered cementitious composite (ECC) in plastic hinge length (PHL) of beam/column members and beam-column joints. A two-story frame structure reduced by a 1:3 scale was further tested through a shake-table (seismic simulator) using multiple levels of simulated earthquake motions. One model conformed to all the ACI-318 requirements for IMRF, whereas the second model used lower-strength concrete in the beam/column members outside PHL. The acceleration time history of the 1994 Northridge earthquake was selected and scaled to multiple levels for shake-table testing. This study reports the observed damage mechanism, lateral strength-displacement capacity curve, and the computed response parameters for each model. The tests verified that nonlinearity remained confined to beam/column ends, i.e., member joint interface. Calculated response modification factors were 11.6 and 9.6 for the code-conforming and concrete strength deficient models. Results show that the RC-ECC frame's performance in design-based and maximum considered earthquakes; without exceeding maximum permissible drift under design-base earthquake motions and not triggering any unstable mode of damage/failure under maximum considered earthquakes. This research also indicates that the introduction of ECC in PHL of the beam/column members' detailing may be relaxed for the IMRF structures.

• Structural Engineering and Mechanics
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• 제29권5호
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• pp.505-530
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• 2008

This paper proposes the application of active multiple tuned mass dampers (AMTMD) for translational and torsional response control of a simplified two-degree-of-freedom (2DOF) structure, able to represent the dynamic characteristics of general asymmetric structures, under the ground acceleration. This 2DOF structure is a generalized 2DOF system of an asymmetric structure with predominant translational and torsional responses under earthquake excitations using the mode reduced-order method. Depending on the ratio of the torsional to the translational eigenfrequency, i.e. the torsional to translational frequency ratio (TTFR), of asymmetric structures, the following three cases can be distinguished: (1) torsionally flexible structures (TTFR < 1.0), (2) torsionally intermediate stiff structures (TTFR = 1.0), and (3) torsionally stiff structures (TTFR > 1.0). The even distribution of the AMTMD within the whole width and half width of the asymmetric structure, thus leading to three cases of installing the AMTMD (referred to as the AMTMD of case 1, AMTMD of case 2, AMTMD of case 3, respectively), is taken into account. In the present study, the criterion for searching the optimum parameters of the AMTMD is defined as the minimization of the minimum values of the maximum translational and torsional displacement dynamic magnification factors (DMF) of an asymmetric structure with the AMTMD. The criterion used for assessing the effectiveness of the AMTMD is selected as the ratio of the minimization of the minimum values of the maximum translational and torsional displacement DMF of the asymmetric structure with the AMTMD to the maximum translational and torsional displacement DMF of the asymmetric structure without the AMTMD. By resorting to these two criteria, a careful examination of the effects of the normalized eccentricity ratio (NER) on the effectiveness and robustness of the AMTMD are carried out in the mitigation of both the translational and torsional responses of the asymmetric structure. Likewise, the effectiveness of a single ATMD with the optimum positions is presented and compared with that of the AMTMD.

• Earthquakes and Structures
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• 제16권5호
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• pp.611-623
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• 2019

A set of mid-rise bare and uniformly infilled reinforced-concrete frame buildings are analyzed for two different seismic intensities of ground-motions (i.e., 'Design Basis Earthquake' and 'Maximum Considered Earthquake') to study their floor response. The crucial parameters affecting seismic design force for acceleration-sensitive non-structural components are studied and compared with the guidelines of the European and the United States standards, and also with the recently developed NIST provisions. It is observed that the provisions of both the European and the United States standards do not account for the effects of the period of vibration of the supporting structure and seismic intensity of ground-motions and thereby provides conservative estimates of the in-structure amplification. In case of bare frames, the herein derived component amplification factors for both the design basis earthquake and the maximum considered earthquake exceeds with their recommended values in the European and the United States standards for non-structural components having periods in vicinity of the higher modes of vibration, whereas, in case of infilled frames, component amplification factors exceeds with their recommended value in the European standard for non-structural components having periods in vicinity of the fundamental mode of vibration, and only for the design basis earthquake. As a consequence of these observations, as well as capping on the design force (in case of United states standard and NIST provisions), in case of the design basis earthquake, the combined amplification factor is underestimated for non-structural components having periods in vicinity of the higher modes of vibration of bare frames, and also for non-structural components having periods in vicinity of the fundamental mode of vibration of infilled frames. At the maximum considered earthquake demand, excepting non-structural components having periods in vicinity of the higher modes of vibration of bare frames, all provisions generally provide conservative estimates of the design floor accelerations.

• 한국전산구조공학회논문집
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• 제23권2호
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• pp.209-215
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• 2010

본 논문에서는 CFD와 FEM에 기초한 진보된 전산해석 기법을 적용하였고 지진에 의한 수평 및 수직방향 기반가진 및 풍하중 효과를 동시에 고려하여 MW급 풍력발전기의 지진응답 해석을 수행하였다. 본 연구에서는 실용적인 응답특성 파악을 위해 시간영역 수치해석기법을 적용하였으며, 지진기반하중 및 풍하중에 의한 영향을 상호 비교하였다. 본 연구의 결과를 통해 관성 특성이 매우 큰 초대형 풍력발전기가 정상작동 조건 중 지진이 유발되는 경우가 타워에 유발되는 응력특성에 큰 영향을 미칠 수 있기 때문에 중요하게 고려될 필요성이 있음을 알 수 있었다.

• 한국공간구조학회논문집
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• 제18권2호
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• pp.35-42
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• 2018

The outrigger damper system is a structural system with excellent lateral resistance when a wind load occurs. However, research on outrigger dampers is still in its infancy. In this study, dynamic response control performance of damper is analyzed according to change of stiffness value and damping value of damper. To do this, a real-scale 3D model of 50 stories has been developed and the artificial wind load has been entered for dynamic analysis. Generally, the larger the damping value, the smaller the stiffness value is, the more effective it is to reduce the maximum displacement and acceleration response. However, the larger the attenuation value as the cost of construction increases, it is necessary to select appropriate stiffness and damping value when applying an outrigger damper.