• Title, Summary, Keyword: 변위증폭 계수

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Displacement Response of Degrading Systems to Near-Fault Ground Motions (근접-단층 지진에 대한 저하시스템의 변위응답)

  • 송종걸
    • Journal of the Earthquake Engineering Society of Korea
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    • v.4 no.2
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    • pp.1-12
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    • 2000
  • 단층에 근접한 지진동에 대하여 성능이 저하되는 단자유도계의 변위응답에 대하여 연구하였다 5% 의 감쇠비를 갖는 세단계의 성능저하시스템을 5개의 단층에 근접한 지진동에 대하여 해석하였다 해석결과로부터 성능저하시스템의 비탄성 변위응답은 비저하시스템에 비하여 큰 값을 나타냄을 알 수 있었다 또한 성능저하 특성이 증가할수록 변위응답은 커지는 경향이 있다 이러한 변위증폭은 구조물의 고유주기 강도와 성능저하특성에 영향을 받으며 짧은 주기영역에서는 큰 값을 나타내며 긴 주기영역에서는 변위증폭이 거의 발생하지 않는다 단층에 근접한 각각의 지진동에 대한 변위증폭의 최대값은 1초 보다 작은 주기영역에서 비저하시스템의 4배 정도이다 변위증폭계수의 평균값은 짧은 주기영역에서는 2의 값을 가지면 구조물의 고유주기가 길어질수록 1에 수렴해 감을 알 수 있었다.

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Verification of the Torsional Amplification Factor for the Seismic Design of Torsionally Imbalanced Buildings (비틀림 비정형 건물의 내진설계를 위한 우발편심 비틀림 증폭계수 검증)

  • Lee, Kwang-Ho;Jeong, Seoung-Hoon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.6
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    • pp.67-74
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    • 2010
  • Because of the difference between the actual and computed eccentricity of buildings, symmetrical buildings will be affected by torsion. In provisions, accidental eccentricity is intended to cover the effect of several factors, such as unfavorable distributions of dead- and live-load masses and the rotational component of ground motion about a vertical axis. The torsional amplification factor is introduced to reduce the vulnerability of torsionally imbalanced buildings. The effect of the torsional amplification factor is observed for a symmetric rectangular building with various aspect ratios, where the seismic-force-resisting elements are positioned at a variable distance from the geometrical center in each direction. For verifying the torsional amplification factor in provisions, nonlinear reinforced concrete models with various eccentricities and aspect ratios are used in rock. The difference between the maximum displacements of the flexible edge obtained between using nonlinear static and time-history analysis is very small but the difference between the maximum torsional angles is large.

Response Modification Factors of Inverted V-type Ordinary Concentrically Braced Frames (역V형 보통가새골조의 반응수정계수)

  • Kim, Jin-Koo;Nam, Kwang-Hee
    • Journal of the Earthquake Engineering Society of Korea
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    • v.8 no.3
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    • pp.53-62
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    • 2004
  • In this paper the overstrength factors, ductility factors, and response modification factors of ordinary concentric braced frames designed in accordance with a current seismic design code are determined by performing pushover analysis. According to the analysis results, the overstrength and the response modification factors turn out to be larger than the values regulated in the codes in most model structures. However if the braces are reinforced by BRB or zipper columns, the overstrength factors and response modification factors turn out to increase significantly.

Simplified Static Analysis of Superstructure on Very Large Floating Structures subjected to Wave Loads (파랑하중을 받는 초대형 부유식 구조물 상부구조체의 실용정적해석법)

  • Song, Hwa-Cheol;Park, Hyo-Seon;Seo, Ji-Hyun
    • Journal of Navigation and Port Research
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    • v.27 no.5
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    • pp.519-526
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    • 2003
  • For preliminary structural analysis of superstructures on very large floating structures(VLFS), superstructures are analyzed considering elastic deformations of barge type lower-structures subjected to wave loads. In this case, to consider the effect of wave loads on the superstructure, initial displacements at the support points of superstructures are evaluated as input data for the analysis. However, the evaluation and application of displacement loads are tedious and very time-consuming processes. Therefore, this paper proposes a simplified static analysis method to analyze the structural behaviors of superstructures on very large floating structures subjected to wave loads. In this study, the member forces due to the variation of beam span and the amplitude and period of wave load are analyzed by using an example 4 span -3 story structure and the amplification factors for beam moments are represented by the specific regression equation.

Deflection Limit on Vibration Serviceability of High-speed Railway Bridges Considering the Effect of Train Speed (열차주행속도를 고려한 고속철도교량의 수직변위에 대한 진동사용성 한계(기준) 연구)

  • Jeon, Bub-Gyu;Kim, Nam-Sik;Kim, Sung-Il
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.473-476
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    • 2011
  • 본 논문에서는 열차와 교량의 상호작용과 주행속도에 의해 결정되어지는 진동지속시간과 차체연직가속도 증폭효과를 고려하여 철도교량의 진동사용성 허용처짐을 제시하고자 하였다. 열차가 교량을 통과할 때의 처짐 형상을 사인파로 가정하고 열차와 교량의 상호작용을 진동전달함수로 표현하여 철도교량의 진동 사용성 허용처짐을 유도하였다. 그리고 진동지속시간을 고려하기 위해 연직가속도 허용기준으로서 진동지속시간을 고려한 교량구조물의 진동사용성기준을 사용하였다. 매개변수연구를 통하여 열차 주행속도의 증가에 비례하여 차체연직가속도는 증가하지만 교량최대변위의 변화는 미미함이 확인됨으로 인하여 차체연직가속도 증가와 동반하여 연직가속도 허용기준역시 증가하는 것을 보정할 필요가 있을 것으로 판단하였다. 따라서 전개된 철도교량의 진동사용성 허용처짐식에 매개변수연구를 통하여 가정한 가속도 증폭계수를 적용하여 열차의 증속에 의한 가속도증폭효과를 고려하였다.

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A Measurement of Target Displacement by Using GB-SAR Interferometry and Atmospheric Correction (GB-SAR의 간섭기법을 통한 물체의 변위 측정 및 대기보정)

  • Lee, Jae-Hee;Lee, Hoon-Yol;Cho, Seong-Jun;Sung, Nak-Hoon;Kim, Jung-Ho
    • Proceedings of the KSRS Conference
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    • pp.25-28
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    • 2008
  • 본 논문에서는 GB-SAR의 간섭기법을 이용하여 물체의 변위 측정에 대한 정밀도를 조사하였으며, 또한 대기보정을 거친 후 정밀도의 변화에 대해서 확인하였다. GB-SAR 시스템에서 안테나는 중심주파수 5.3 GHz, 밴드 폭 600 MHz인 C밴드 안테나를 사용하였고, 신호의 증폭을 위해 마이크로파 앰프를, 다편파 측정 및 분석을 위하여 스위치를 장착하였다. 레일의 총 길이는 5 m, 이동간격은 5 cm, 최대 관측 거리는 약 200 m이다. 변위 측정에 사용된 이동산란체는 trihedral corner reflector로서, 시스템 전방 약 160 m에 위치하며 시스템 방향으로 1 mm에서 40 mm 전진시켰다. 이동산란체의 실제 변위와 GB-SAR 시스템의 위상변화로 관측된 변위의 상관계수는 편파에 따라 0.9995에서 0.9996으로 나타났다. 마이크로파의 전파과정에서 거리와 습도에 따른 지연 효과를 고려하기 위하여 대기보정식을 구하였으며, 이를 이동산란체의 위상에 적용한 결과 상관계수는 0.9997에서 0.9999의 값을 나타냈고 40 mm 이동시 오차가 1 mm 이내를 나타냄으로서 대기보정을 통한 결과가 더 높은 정밀도를 나타냄을 확인하였다.

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Modal Characteristics of a Structure with Stiffness and Damping Eccentricit (강성 및 감쇠 비대칭 구조물의 모드 특성)

  • 김진구;방성혁
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.3
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    • pp.421-432
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    • 2002
  • In this study the modal characteristics and responses of an asymmetric structure with added viscoelastic dampers were investigated for design parameters such as eccentricity of stiffness and added dampers, the loss factor of the damping materials used. For modal characteristics, variation of the quantities such as natural frequencies, modal damping ratios, modal participation factors, and dynamic amplification factors were observed, and displacements at flexible and stiff edges, and at center of mass were obtained. Based on the results, the problem of the optimum damper distribution to minimize the torsional effects was addressed, and the proposed method for optimum damper distribution was applied to a multi-story structure to verify the applicability Finally the effect of viscous and viscoelastic dampers were compared by varying the loss factor of the viscoelastic material.

Effect of Vertical Irregularity on Displacement Concentration in Building Seismic Design Based on Linear Analysis (선형 기반 내진설계 해석법에 따른 수직비정형성 건축물의 변위집중 분석)

  • Sohn, Jung-Hoon;Choi, Insub;Kim, JunHee
    • Journal of the Architectural Institute of Korea
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    • v.36 no.6
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    • pp.193-200
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    • 2020
  • Recently, earthquakes with a magnitude of 5.0 or more have occurred in Pohang and Gyeongju in Korea, and the demands for seismic performance evaluation of buildings has been increasing. In particular, in the case of Pohang earthquake induced a significant damage to the middle and low rise piloti buildings. The purpose of this paper is to investigate the effects of displacement concentration on the buildings with the vertical irregularity subjected to horizontal shear forces. Displacement Concentration Factor (DCF) was defined as the displacement ratio of the first story to the top story to quantitatively analyze the degree of displacement concentration between equivalent static analysis and response spectrum analysis for the buildings with vertical irregularity. Displacement Concentration Amplification Factor (DCAF) was defined as the DCF ratio of the response spectrum method to the equivalent static analysis to compare displacement concentration on soft story. In this paper, DCAF according to the stiffness ratio of soft story and the number of story was analyzed through 2D model. Also DCAF value of 2D model was verified by 3D prototype model of 4-story piloti structure. The DCAF value tended to increase as the stiffness ratio decreased and the number of story increased. It was confirmed that the response spectrum method should be applied instead equivalent static analysis when the DCAF value is 1.35 or more according to the criteria of KBC 2016.

A Study of Displacement Amplification Factors Considering Hysteretic Behavior of Structural Systems and Earthquake Characteristics (비탄성 이력응답 및 지진특성을 반영한 변위증폭계수에 관한 연구)

  • Song, Jong-Keol;Kim, Hark-Soo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.777-782
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    • 2007
  • Displacement amplification factor can be used to estimate inelastic displacement demands from elastic displacement demands, The simple formula for displacement amplification factor considering hysteretic behavior of structural system and earthquake characteristics is proposed. And the effects of several parameters such as displacement ductility, strain hardening ratio, period, characteristics of earthquakes and hysteretic models for the displacement amplification factor are evaluated. Accuracy of the proposed formula is evaluated by comparing the displacement amplification factors estimated by existing and proposed formula with those calculated from inelastic time history analysis. The displacement amplification factors by proposed formulas provide a good agreement with those calculated by inelastic time history analysis.

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Seismic Amplification Characteristics of Eastern Siberia (동시베리아 지역의 지진 증폭 특성)

  • Park, Du-Hee;Kwak, Hyung-Joo;Kang, Jae-Mo;Lee, Yong-Gook
    • Journal of the Korean Geotechnical Society
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    • v.30 no.10
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    • pp.67-80
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    • 2014
  • The thickness of permafrost in Eastern Siberia is from 200 to 500 meters. The seasonally frozen layer can vary from 0 to 4m depending on ground temperature and its location. The shear wave velocity varies from 80m/s in summer to 1500m/s in winter depending on soil type. When melted, large impedence will occur due to the difference between the shear wave velocity of seasonally frozen soil and that of permafrost layer. Large displacement may occur at the boundary of the melted and the frozen layer, and this phenomenon should be considered in a seismic design. In this research, one-dimensional equivalent linear analyses were performed to investigate the effects of the seasonally frozen layer on ground amplification characteristics. Soil profiles of Yakutsk and Chara in Eastern Siberia were selected from geotechnical reports. 20 recorded ground motions were used to evaluate the effect of input motions. As the thickness of seasonally frozen layer and the difference in the shear wave velocity increases, the amplification is shown to increase. Peat, very soft organic soil widely distributed throughout Eastern Siberia, is shown to cause significant ground motion amplification. It is therefore recommended to account for its influence on propagated motion.