• Title, Summary, Keyword: 강성 및 강도 저하

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Seismic Capacity of Non-seismic Designed RC Framed Building Retrofitted by CBD System (CBD 시스템으로 보강된 비내진 RC 골조의 내진성능 평가)

  • Hur, Moo-Won;Lee, Sang-Hyun;Chun, Young-Soo
    • Journal of the Korea Concrete Institute
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    • v.27 no.6
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    • pp.625-632
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    • 2015
  • In this study, a comparative analysis have been conducted to examine seismic reinforcement effect of a school building that is designed with a CBD (Channel Beam Damper) system supported by H-frame with existing non-seismic RC frame. As a result of experiment, seismic reinforcement specimen with CBD system showed hysteretic characteristics of a large ellipse with great energy dissipation ability and increased strength and stiffness, while non-seismic design specimen showed rapid reduction in strength and brittle shear failure at top and bottom of the left and right column. In addition, comparing the stiffness reduction between the two specimens, CBD system was effective in preventing the reduction of stiffness. Energy dissipation ability of specimen reinforced by CBD system was about 4.0 times higher than the non-reinforced specimen. Such enhancement in energy dissipation ability could be considered as the result of improved strength and deformation for further application in designing of seismic reinforcement.

Seismic Capacity of Non-seismic Designed RC Framed Building Retrofitted by Double I-type Metallic Damper (더블 I형 감쇠장치로 보강한 비내진 RC 골조의 내진성능 평가)

  • Hur, Moo-Won;Chun, Young-Soo;Hwang, Jae-Seung;Kim, Jong-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.6
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    • pp.10-17
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    • 2015
  • In this study, to examine seismic reinforcement effect of a school building constructed prior to application of seismic design, a Double I-type damper supported by wall was installed to perform comparative analysis on existing non-seismic designed RC frame. As a result of experiment, while non-seismic designed specimen showed rapid reduction in strength and brittle shear destruction as damages were focused on top and bottom of left and right columns, reinforced specimen showed hysteretic characteristics of a large ellipse with great energy absorption ability, exhibiting perfectly behavior with increased strength and stiffness from damper reinforcement. In addition, as a result of comparing stiffness reduction between the two specimens, specimen reinforced by shear wall type damper was effective in preventing stiffness reduction. Energy dissipation ability of specimen reinforced by Double I-type damper was about 3.5 times as high as energy dissipation ability of non-reinforced specimen. Such enhancement in energy dissipation ability is considered to be the result of improved strength and deformation.

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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Investigation on Failure Behavior of Varying Ratios of Recycled Aggregate (순환골재 치환률에 따른 압축강도 비교분석)

  • Jang, Hoon;Chung, Wonseok;An, Zu-Og
    • 한국방재학회:학술대회논문집
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    • pp.160-160
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    • 2011
  • 현대의 건설기술은 자원절약과 환경보전이라는 시대적 흐름 속에, 자원순환과 지속 가능한 친환경 건설기술 개발은 차세대 연구분야로써, 연구가 시급한 분야가 되었다. 최근에는 골재 수급불균형 문제를 해결하고 동시에 자원순환을 위한 방안으로서 건설폐기물로부터 생산된 순환골재를 콘크리트용 천연골재의 대체재로 활용하기 위한 연구개발이 이루어지고 있다. 지속가능형 건설기술을 국내 독자 기술로 확립하고 건설현장에서 발생하는 폐기물의 순환시스템을 확고하게 구축하여 순환자원에 의한 국가경쟁력 강화를 기대할 수 있다. 본 연구의 목적은 순환골재 콘크리트의 역학적 특성을 개선하기 위해 순환골재 콘크리트 공시체를 제작하여 강도 및 강성을 검증하는 것이다. 실험방법으로 순환굵은골재의 치환 비율을 0%에서 100%까지 변화시킨 공시체를 제작하고 각 공시체의 정적 극한강도 거동을 비교 분석하였다. 하중은 공시체가 파괴가 발생 할 때까지 변위제어 방식으로 재하 하였으며 이 때 공시체의 파괴거동은 설치된 계측센서들을 이용하여 계측 및 분석하였다. 실험결과 공시체의 압축강도는 순환굵은골재 치환률이 25% 미만일 경우 일반 콘크리트 압축강도의 95% 이상의 구조성능을 갖지만, 순환굵은골재 치환률이 100%인 경우, 일반콘크리트 압축강도의 85% 수준의 구조성능을 나타냈다. 강성은 FRP 부재의 순환골재 치환률에 따라 최대 14%의 강성차이를 보였다. 이를 통해 순환골재 치환률이 높을수록 순환골재 표면의 폐모르타르와 이물질의 영향으로 재료간의 부착강도가 감소되어 강도와 강성이 저하되었음을 확인하였다.

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Analytic Model for Hysteretic Behavior of Reinforced Concrete Members (철근 콘크리트 부재의 히스테레틱 거동의 해석방법)

  • ;;C. Meyer
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.96-101
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    • 1990
  • 본 논문은 반복하중에 의한 콘크리트 부재거동에 대한 수학적인 해석방법에 관한 것으로서 철근콘크리트 부재의 Hysteretic 거동의 주요한 현상들인 강성저하, 강도저하 그리고 전단영향 등의 수치해석 Model을 소개하였다. 그리고 본 해석 Model의 정확성 및 사용성 등을 평가하기 위하여 R.C.콘크리트 부재에 대한 수치 해석 예제를 제시하였다.

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Estimation of Compressive Stiffness of Polyurethane Rubber Springs and Its Application (폴리우레탄 고무 스프링의 압축 강성도 추정 및 적용)

  • Choi, Eunsoo;Park, Seungjin;Woo, Daeseung
    • Journal of Korean Society of Steel Construction
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    • v.29 no.3
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    • pp.229-236
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    • 2017
  • The purpose of this study is to investigate the behavior and characteristics of rubber springs and calculate the compressive stiffness by performing dynamic compression tests of rubber springs. In order to carry out the dynamic compression test of rubber spring, total 9 rubber springs were tailored by calculating the shape factor of L80-D55, L90-D58, and L100-D60, and used for the experiments. Experiments were performed by controlling the compression according to the length of the rubber spring, and the compression was increased in the order of 5%, 10%, 15%, 20% and 25% of the strain. From the experimental results, the force-strain curves were obtained and it was confirmed that strength decrease and strength increase phenomenon occurred as the strain increased. In addition, it was confirmed that the decrease of stiffness and the increase of stiffness were clearly observed according to the size and diameter of the rubber spring, and the effective compression stiffness was estimated using the slope of the force-strain curve. By using the effective compressive stiffness, design values that can be used in actual design were presented.

Experimental Test for Seismic Performance of PCS Structural System (PCS 구조 시스템의 내진 성능 분석)

  • Park, Soon-Kyu;Yeo, In-Seok
    • Journal of the Korea Concrete Institute
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    • v.19 no.3
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    • pp.313-322
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    • 2007
  • The PCS system, which consists of precast concrete column and steel beam, is a kind of composite structural systems. In this paper, experimental study has been conducted to analyze seismic performance of bolted beam-to-column connections for the PCS system. Based on experimental results from the seismic testing of eight interior PCS specimens, it shows that behavior of PCS system is satisfactory to seismic performance criteria of ACI such as strength deterioration, stiffness degradation and energy dissipation capacity except initial stiffness. All of the specimens maintain their strength at large levels of story drift without significant loss of stiffness and show high ductility level for inelastic behavior. The energy dissipation capacity is two times greater than requirement of ACI criterion. But the initial stiffness of all specimens does not satisfy ACI criterion, and this phenomenon is similar to the other composite structural systems such as RCS, CFT system.

An Experimental Study on the MSG Reinforcement of Steel Pipe Pile Installed by PRD (MSG공법에 의한 PRD강관말뚝 보강에 관한 사례 연구)

  • Chun, Byungsik;Kang, Heejin;Kong, Jinyoung
    • Journal of the Korean Geoenvironmental Society
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    • v.8 no.6
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    • pp.5-12
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    • 2007
  • Mudstone has characteristics that it has high enough strength and stiffness in a dry condition, but the strength and stiffness decrease in a wet condition with groundwater infiltration. The sliding of cut slope frequently encountered in Pohang area has been reported due to the rapid reduction of shear strength in mudstone after being exposed to the air. The study in this paper shows that mudstone having enough strength in a boring stage has lost the strength after installing PRD (percussion rotary drill) steel pipe pile inducing an insufficient bearing capacity. Field test has been performed to investigate the most favorable method for increasing a pile bearing capacity in mudstone with various methods such as MSG (Micro Silica Grouting) around the tip and side of a pile, the perimeter grouting combined with Micro pile reinforcement, and concrete filling after tip reinforcing grouting. MSG has been turned out to be the most favorable method for increasing a pile bearing capacity in mudstone, confirmed by the static load test.

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Strength Prediction on Composite Laminates Including Material Nonlinearity and Continuum Damage Mechanics (재료 비선형과 연속체 손상역학을 고려한 복합 적층판의 강도 예측)

  • Park, Kook-Jin;Kang, Hee-Jin;Shin, Sangjoon;Choi, Ik-Hyun;Kim, Minki;Kim, Seung-Jo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.11
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    • pp.927-936
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    • 2014
  • This paper presents development and verification of the progressive failure analysis upon the composite laminates. Strength and stiffness of the fiber-reinforced composite are analyzed by property degradation approach with emphasis on the material nonlinearity and continuum damage mechanics (CDM). Longitudinal and transverse tensile modes derived from Hashin's failure criterion are used to predict the thresholds for damage initiation and growth. The modified Newton-Raphson iterative procedure is implemented for determining nonlinear elastic and viscoelastic constitutive relations. Laminar properties of the composite are obtained by experiments. Prediction on the un-notched tensile (UNT) specimen is performed under the laminate level. Stress-strain curves and strength results are compared with the experimental measurement. It is concluded that the present nonlinear CDM approach is capable of predicting the strength and stiffness more accurately than the corresponding linear CDM one does.