• 제목/요약/키워드: seismic engineering

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TUTUM Easy-seismic: 소방시설 내진설계 자동화 소프트웨어 개발 (TUTUM Easy-seismic: Development of a Seismic Design Automation Software for Building Fire Protection Systems)

  • 오창수;최준호
    • 한국화재소방학회논문지
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    • 제33권5호
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    • pp.140-148
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    • 2019
  • '소방시설 내진설계 의무화'에 발맞추어 내진설계의 신뢰성과 효율성 향상을 위해서는 설계 자동화 소프트웨어 개발이 필수불가결하다. 본 연구에서 개발한 내진 설계 자동화 S/W는 소방청의 「소방시설의 내진설계 기준(이하 "국내 기준")」에 따른 흔들림 방지 버팀대(이하 "버팀대")의 자동 배치, 계산서 출력 및 그리고 물량 자동 산출 등의 기능을 제공한다. 또한, 자동화 S/W는 설계자의 수동설계와 비교하였을 때 약 3배 정도의 업무 속도를 단축시켜줄 뿐만 아니라 버팀대 등의 설계물량과 관련한 휴먼에러를 줄임으로써 설계안의 신뢰성을 높여준다. 뿐만 아니라 그동안 보수적으로 접근했던 소방시설의 내진설계방식에 있어 적어도 버팀대 사용에 대해서 컴퓨터 알고리즘을 이용한 최적의 내진설계를 수행할 수 있었다.

일본 원전 내진설계 기술기준을 적용한 모의지진파(가속 도시간이력) 작성 (Generation of Design Time History Complying With Japanese Seismic Design Standards for Nuclear Power Plants)

  • 진승민;김용복;이용선;문일환
    • 한국지진공학회논문집
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    • 제25권2호
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    • pp.83-91
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    • 2021
  • Seismic designs for Korean nuclear power plants (NPPs) under earthquakes' design basis are noticed due to the recent earthquake events in Korea and Japan. Japan has developed the technologies and experiences of the NPPs through theoretical research and experimental verification with extensively accumulated measurement data. This paper describes the main features of the design-time history complying with the Japanese seismic design standard. Proper seed motions in the earthquake catalog are used to generate one set of design time histories. A magnitude and epicentral distance specify the amplitude envelope function configuring the shape of the earthquake. Cumulative velocity response spectral values of the design time histories are compared and checked to the target response spectra. Spectral accelerations of the time histories and the multiple-damping target response spectra are also checked to exceed. The generated design time histories are input to the reactor building seismic analyses with fixed-base boundary conditions to calculate the seismic responses. Another set of design time histories is generated to comply with Korean seismic design procedures for NPPs and used for seismic input motions to the same reactor containment building seismic analyses. The responses at the dome apex of the building are compared and analyzed. The generated design time histories will be also applied to subsequent seismic analyses of other Korean standard NPP structures.

고진동수 지진에 대한 기기 정착부의 비탄성 거동을 고려한 지진취약도 평가 (Seismic Fragility Analysis Considering the Inelastic Behavior of Equipment Anchorages for High-Frequency Earthquakes)

  • 임승현;곽신영;최인길;정재욱;김석철
    • 한국지진공학회논문집
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    • 제25권6호
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    • pp.261-266
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    • 2021
  • Nuclear power plants in Korea were designed and evaluated based on the NRC's Regulatory Guide 1.60, a design response spectrum for nuclear power plants. However, it can be seen that the seismic motion characteristics are different when analyzing the Gyeongju earthquake and the Pohang earthquake that has recently occurred in Korea. Compared to the design response spectrum, seismic motion characteristics in Korea have a larger spectral acceleration in the high-frequency region. Therefore, in the case of equipment with a high natural frequency installed in a nuclear power plant, seismic performance may be reduced by reflecting the characteristics of domestic seismic motions. The failure modes of the equipment are typically structural failure and functional failure, with an anchorage failure being a representative type of structural failure. In this study, comparative analyses were performed to decide whether to consider the inelastic behavior of the anchorage or not. As a result, it was confirmed that the seismic performance of the anchorages could be increased by considering the inelastic behavior of an anchorage.

노후도를 고려한 교량의 시스템-수준 지진취약도 평가 (System-Level Seismic Fragility Evaluation of Bridge Considering Aging Effects)

  • 꽁씨나;문지호;송종걸
    • 한국전산구조공학회논문집
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    • 제35권3호
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    • pp.149-158
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    • 2022
  • 교량은 사용년한이 증가함에 따라 노후화로 인해 역학적인 성질과 구조적인 성능이 저하되고, 이로 인해서 강진 시에 내진성능이 저하된다. 교각과 교량받침에 대한 노후화를 몇 가지 단계로 정량화하여 해석모델에 반영하였고, 노후화된 교각과 교량받침에 대하여 부재-수준의 지진취약도를 평가하였다. 교량 시스템의 파괴 메카니즘을 직렬시스템으로 가정하여, 부재-수준의 지진취약도 해석 결과로부터 시스템-수준의 지진취약도를 평가하는 방법을 제안하였다. 노후도에 취약한 부재인 교각과 교량받침에 대하여 5가지 정량적인 노후도(0, 5, 10, 25, 40%)를 가정하여 부재-수준의 지진취약도를 평가하였고, 이 결과로부터 시스템-수준의 지진취약도 평가를 수행하였다. 시스템-수준의 지진취약도는 교량받침 보다는 교각이 지배적인 영향을 줌을 알 수 있었다. 이는 보다 취약한 구조부재의 지진취약도가 전체 교량시스템의 지진취약도에 지배적인 영향을 주는 것을 의미한다.

Seismic fragility performance of skewed and curved bridges in low-to-moderate seismic region

  • Chen, Luke;Chen, Suren
    • Earthquakes and Structures
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    • 제10권4호
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    • pp.789-810
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    • 2016
  • Reinforced concrete (RC) bridges with both skew and curvature are pretty common in areas with complex terrains. Existing studies have shown skewed and/or curved bridges exhibit more complicated seismic performance than straight bridges, and yet related seismic risk studies are still rare. These bridges deserve more studies in low-to-moderate seismic regions than those in seismic-prone areas. This is because for bridges with irregular and complex geometric designs, comprehensive seismic analysis is not always required and little knowledge about actual seismic risks for these bridges in low-to-moderate regions is available. To provide more insightful understanding of the seismic risks and the impact from the geometric configurations, analytical fragility studies are carried out on four typical bridge designs with different geometric configurations (i.e., straight, curved, skewed, skewed and curved) in the mountain west region of the United States. The results show the curved and skewed geometries can considerably affect the bridge seismic fragility in a complex manner, underscoring the importance of conducting detailed seismic risk assessment of skewed and curved bridges in low-to-moderate seismic regions.

Seismic probabilistic risk assessment of weir structures considering the earthquake hazard in the Korean Peninsula

  • Alam, Jahangir;Kim, Dookie;Choi, Byounghan
    • Earthquakes and Structures
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    • 제13권4호
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    • pp.421-427
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    • 2017
  • Seismic safety evaluation of weir structure is significant considering the catastrophic economical consequence of operational disruption. In recent years, the seismic probabilistic risk assessment (SPRA) has been issued as a key area of research for the hydraulic system to mitigate and manage the risk. The aim of this paper is to assess the seismic probabilistic risk of weir structures employing the seismic hazard and the structural fragility in Korea. At the first stage, probabilistic seismic hazard analysis (PSHA) approach is performed to extract the hazard curve at the weir site using the seismic and geological data. Thereafter, the seismic fragility that defines the probability of structural collapse is evaluated by using the incremental dynamic analysis (IDA) method in accordance with the four different design limit states as failure identification criteria. Consequently, by combining the seismic hazard and fragility results, the seismic risk curves are developed that contain helpful information for risk management of hydraulic structures. The tensile stress of the mass concrete is found to be more vulnerable than other design criteria. The hazard deaggregation illustrates that moderate size and far source earthquakes are the most likely scenario for the site. In addition, the annual loss curves for two different hazard source models corresponding to design limit states are extracted.

플랜트 설비 지지용 대안 강구조 시스템의 내진성능 (Seismic Performance of Alternative Steel Structural Systems for an Equipment-Supporting Plant Structure)

  • 곽병훈;안숙진;박지훈
    • 한국지진공학회논문집
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    • 제27권1호
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    • pp.13-24
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    • 2023
  • In this study, alternative seismic force-resisting systems for plant structure supporting equipment were designed, and the seismic performance thereof was compared using nonlinear dynamic analysis. One alternative seismic force-resisting system was designed per the requirement for ordinary moment-resisting and concentrically braced frames but with a reduced base shear. The other seismic force-resisting system was designed by accommodating seismic details of intermediate and unique moment-resisting frames and special concentrically braced frames. Different plastic hinge models were applied to ordinary and ductile systems based on the validation using existing test results. The control model obtained by code-based flexible design and/or reduction of base shear did not satisfy the seismic performance objectives, but the alternative structural system did by strengthened panel zones and a reduced effective buckling length. The seismic force to equipment calculated from the nonlinear dynamic analysis was significantly lower than the equivalent static force of KDS 41 17 00. The comparison of design alternatives showed that the seismic performance required for a plant structure could be secured economically by using performance-based design and alternative seismic-force resisting systems adopting minimally modified seismic details.

다중기기 손상 상관성에 의한 지진리스크 영향 분석 (Influence Analysis of Seismic Risk due to the Failure Correlation in Seismic Probabilistic Safety Assessment)

  • 임승현;최인길
    • 한국지진공학회논문집
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    • 제23권2호
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    • pp.101-108
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    • 2019
  • The seismic safety of nuclear power plants has always been emphasized by the effects of accidents. In general, the seismic safety evaluation of nuclear power plants carries out a seismic probabilistic safety assessment. The current probabilistic safety assessment assumes that damage to the structure, system, and components (SSCs) occurs independently to each other or perfect dependently to each other. In case of earthquake events, the failure event occurs with the correlation due to the correlation between the seismic response of the SSCs and the seismic performance of the SSCs. In this study, the EEMS (External Event Mensuration System) code is developed which can perform the seismic probabilistic safety assessment considering correlation. The developed code is verified by comparing with the multiplier n, which is for calculating the joint probability of failure, which is proposed by Mankamo. It is analyzed the changes in seismic fragility curves and seismic risks with correlation. As a result, it was confirmed that the seismic fragility curves and seismic risk change according to the failure correlation coefficient. This means that it is important to select an appropriate failure correlation coefficient in order to perform a seismic probabilistic safety assessment. And also, it was confirmed that carrying out the seismic probabilistic safety assessment in consideration of the seismic correlation provides more realistic results, rather than providing conservative or non-conservative results comparing with that damage to the SSCs occurs independently.

Effect of seismic acceleration directions on dynamic earth pressures in retaining structures

  • Nian, Ting-Kai;Liu, Bo;Han, Jie;Huang, Run-Qiu
    • Geomechanics and Engineering
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    • 제7권3호
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    • pp.263-277
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    • 2014
  • In the conventional design of retaining structures in a seismic zone, seismic inertia forces are commonly assumed to act upwards and towards the wall facing to cause a maximum active thrust or act upwards and towards the backfill to cause a minimum passive resistance. However, under certain circumstances this design approach might underestimate the dynamic active thrust or overestimate the dynamic passive resistance acting on a rigid retaining structure. In this study, a new analytical method for dynamic active and passive forces in c-${\phi}$ soils with an infinite slope was proposed based on the Rankine earth pressure theory and the Mohr-Coulomb yield criterion, to investigate the influence of seismic inertia force directions on the total active and passive forces. Four combinations of seismic acceleration with both vertical (upwards or downwards) and horizontal (towards the wall or backfill) directions, were considered. A series of dimensionless dynamic active and passive force charts were developed to evaluate the key influence factors, such as backfill inclination ${\beta}$, dimensionless cohesion $c/{\gamma}H$, friction angle ${\phi}$, horizontal and vertical seismic coefficients, $k _h$ and $k_v$. A comparative study shows that a combination of downward and towards-the-wall seismic inertia forces causes a maximum active thrust while a combination of upward and towards-the-wall seismic inertia forces causes a minimum passive resistance. This finding is recommended for use in the design of retaining structures in a seismic zone.

Seismic analysis of half-through steel truss arch bridge considering superstructure

  • Li, Ruiqi;Yuan, Xinzhe;Yuan, Wancheng;Dang, Xinzhi;Shen, Guoyu
    • Structural Engineering and Mechanics
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    • 제59권3호
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    • pp.387-401
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    • 2016
  • This paper takes a half-through steel truss arch bridge as an example. A seismic analysis is conducted with nonlinear finite element method. Contrast models are established to discuss the effect of simplified method for main girder on the accuracy of the result. The influence of seismic wave direction and wave-passage on seismic behaviors are analysed as well as the superstructure and arch ring interaction which is mostly related with the supported bearings and wind resistant springs. In the end, the application of cable-sliding aseismic devices is discussed to put forward a layout principle. The main conclusions include: (1) The seismic response isn't too distinctive with the simplified method of main girder. Generally speaking, the grillage method is recommended. (2) Under seismic input from different directions, arch foot is usually the mostly dangerous section. (3) Vertical wave input and horizontal wave-passage greatly influence the seismic responses of arch ring, significantly increasing that of midspan. (4) The superstructure interaction has an obvious impact on the seismic performance. Half-through arch bridges with long spandrel columns fixed has a less response than those with short ones fixed. And a large stiffness of wind resistant spring makes the the seismic responses of arch ring larger. (5) A good isolation effectiveness for half-through arch bridge can be achieved by a reasonable arrangement of CSFABs.