• Title/Summary/Keyword: Floor spectrum

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Floor Response Spectrum Analysis of a Base-isolated Nuclear Power Plant (면진원전의 층응답스펙트럼 해석)

  • Jung, Jae-Wook;Lee, Sangmin;Hong, Jung-Wuk
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.29 no.4
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    • pp.355-362
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    • 2016
  • In order to secure the stability against strong earthquakes, isolation devices on the existing nuclear power plant have been introduced. By applying the isolation device on structures, it is possible to isolate structures from the ground motion. Therefore, the natural frequencies of the structures become longer, and the responses of the structures due to the ground motion decrease. Especially, when designing the nuclear power plant, it is important to ensure the safety of internal devices as well as the nuclear power plant itself. The floor response spectrum is commonly used in designing the internal devices. In this research, floor response spectrum is evaluated and the effect of second hardening behavior is investigated by performing earthquake analysis.

Modified complex mode superposition design response spectrum method and parameters optimization for linear seismic base-isolation structures

  • Huang, Dong-Mei;Ren, Wei-Xin;Mao, Yun
    • Earthquakes and Structures
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    • v.4 no.4
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    • pp.341-363
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    • 2013
  • Earthquake response calculation, parametric analysis and seismic parameter optimization of base-isolated structures are some critical issues for seismic design of base-isolated structures. To calculate the earthquake responses for such non-symmetric and non-classical damping linear systems and to implement the earthquake resistant design codes, a modified complex mode superposition design response spectrum method is put forward. Furthermore, to do parameter optimization for base-isolation structures, a graphical approach is proposed by analyzing the relationship between the base shear ratio of a seismic base-isolation floor to non-seismic base-isolation one and frequency ratio-damping ratio, as well as the relationship between the seismic base-isolation floor displacement and frequency ratio-damping ratio. In addition, the influences of mode number and site classification on the seismic base-isolation structure and corresponding optimum parameters are investigated. It is demonstrated that the modified complex mode superposition design response spectrum method is more precise and more convenient to engineering applications for utilizing the damping reduction factors and the design response spectrum, and the proposed graphical approach for parameter optimization of seismic base-isolation structures is compendious and feasible.

Evaluation on the Floor Vibration Characteristics for the Vibration Control of Vibration Sensitive Equipments (정밀 혐진기기 방.제진을 위한 바닥 진동성능평가에 관한 연구)

  • Lee, Ho-Beom;Lho, Byeong-Cheol;Cho, Dong-Jin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.933-939
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    • 2000
  • In this paper we present an overview of the factors and techniques that must be considered in vibration measurements in the floor structures for microelectronics facilities. Normally narrowband vibration spectrum or equivalent signals are suggested as the guide indexes of site vibration phenomina. But it cannot support perfect informations in designing vibration control systems for the vibration sensitive equipment even though the spectrum serves to illustrate the fact that most real vibration environments are dominated by broadband energy as opposed to tonal energy. The major topics cover stiffness in frequency and time domain, acceleration level and modal characteristics from experimental modal analysis as well as narrowband spectrum. The combined signal analysis through the items mentioned above can give better solutions and would be positively recomended to solve the vibration problems on a sort of limited field.

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Seismic Analysis of Power Plant Piping System (발전소 배관계의 내진해석)

  • Kim, Jeong-Hyun;Lee, Young-Shin;Kim, Yeon-Whan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2011.10a
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    • pp.480-485
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    • 2011
  • In this study, the seismic analysis of power plant piping system was performed using finite element model. This study was performed by ANSYS 12.1. For qualification of power plant piping system, the response spectrum analysis was performed using the given operating basis earthquake(OBE) and safe shutdown earthquake(SSE) floor response spectrum. The maximum stresses of power plant piping system were 166 MPa under OBE condition and 281 MPa under SSE condition. Thus, it can shown that the structural integrity of tpower plant piping system has a stable structure for seismic load conditions.

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Generation of Floor Response Spectra including Equipment-Structure Interaction in Frequency Domain (진동수 영역에서 기기-구조물 상호작용을 고려한 층응답스펙트럼의 작성)

  • Choi, Dong-Ho;Lee, Sang-Hoon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.9 no.6 s.46
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    • pp.13-19
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    • 2005
  • Floor response spectra for dynamic response of subsystem such as equipment, or piping in nuclear power plants are usually generated without considering dynamic interaction between main structure and subsystem. This study describes the analytic method in which equipment response spectra can be obtained through dynamic analysis considering equipment-structure Interaction(ESI). In this method, dynamic response of the equipment by this method is based on a dynamic substructure method in which the equipment-structure system is partitioned into the single-degree-ol-freedom system(SDOF) representing the equipment and the equipment support impedance representing the dynamic charactenstics of the structure ai the equipment support. A family of equipment response spectra is developed by applying this method to calculate the maximum responses of a family of SDOF equipment systems with wide banded equipment frequency, damping ratio, and mass. The method is validated by comparing the floor response spectrum from this method with the floor response spectrum generated from the rigorous analysis including equipments on the containment building of a prototypical nuclear power plant. in order to Investigate ESI effect in the response of equipment, response values from the method and the conventional approach without considering ESI are compared for the equipment having the mass less than 1% of the total structural mass. Response spectra from the method showed lower spectral amplitudes than those of the conventional floor response spectra around controlling frequencies.

A Method for Generating Floor Response Spectra for Seismic Design for Non-Structural Components (비구조요소의 내진 설계를 위한 층응답스펙트럼 생성 기법)

  • Chang, Sung-Jin;Park, Dong-Uk;Kim, Jae-Bong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.1
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    • pp.154-162
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    • 2019
  • Large scale damage has been globally increased due to natural disasters such as earthquake. Although a variety of studies secured seismic performance of buildings, casualties and economic loss have occurred because of poor security of seismic performance in non-structural components. Structure's location on which non-structural components are installed and characteristics of vibration occurring on each position of structures are varied, so a response spectrum is required for each position of structures. In addition, a response spectrum occurring in a structure is different, depending on the form of it and positions on which it is installed. Therefore, selection of a response spectrum is important, so a definite method for calculating the response spectrum which acts on non-structural components is necessary. A method for choosing a response spectrum is suggested in this paper, and a structural analysis was conducted with the suggested method, by selecting a ground response spectrum and a structural system, which may occur in Korea. Moreover, it helps create a response spectrum necessary for a seismic test of non-structural components, by suggesting the method for deduction it, with a simple formula.

Seismic Analysis of Traveling Sea Water Screen (해수여과장치의 내진해석)

  • Kim, Heung-Tae;Lee, Young-Shin;Park, Young-Moon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.3
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    • pp.289-294
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    • 2011
  • In this study, the seismic analysis of traveling sea water screen for nuclear power plant was performed using finite element model. For qualification of traveling sea water screen, the response spectrum analysis was performed using the given operating basis earthquake(OBE) and safe shutdown earthquake(SSE) floor response spectrum. Dynamic analysis of water sea traveling screen was performed using finite element method. The analytical maximum displacements of traveling sea water screen were 2.5 mm under OBE condition and 4.6 mm under SSE condition. The maximum stresses of traveling sea water screen were 24 MPa under OBE condition and 44 MPa under SSE condition, that this results were 18 %, 27% of yield strength of material. Thus, it can shown that the structural integrity of traveling sea water screen has a stable structure for seismic load conditions.

Noise and Vibration Characteristics of Heavy-weight floor impact by Using Damping Materials (감쇠재 사용에 따른 중량충격음의 소음 및 진동특성)

  • Jeon, Jin-Yong;Jeong, Young;Song, Hee-Soo;Kim, Min-Bae;Lee, Young-Je
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.97-102
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    • 2004
  • The Characteristics of noise and vibration by heavy-weight floor impact sound was studied. Resonance frequency increased a little in structures that use damping material in living room and bedroom, and acceleration waves length that respond became short, and displayed aspect that oscillation level decreases. Result that measure sound pressure level, structure that compare and applies damping materials with structure that apply the resilient materials from 63Hz lower part that impact energy is concentrated in energy spectrum of heavy-weight floor impact sound displayed result that sound pressure, level decreases remarkably. Therefore, according to use of damping materials, confirmed reduction effect of heavy-weight floor impact sound.

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Limit states of RC structures with first floor irregularities

  • Favvata, Maria J.;Naoum, Maria C.;Karayannis, Chris G.
    • Structural Engineering and Mechanics
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    • v.47 no.6
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    • pp.791-818
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    • 2013
  • The seismic performance of reinforced concrete (RC) frame structures with irregularities leading to soft first floor is studied using capacity assessment procedures. The soft first story effect is investigated for the cases: (i) slab-column connections without beams at the first floor, (ii) tall first story height and (iii) pilotis type building (open ground story). The effects of the first floor irregularity on the RC frame structure performance stages at global and local level (limit states) are investigated. Assessment based on the Capacity Spectrum Method (ATC-40) and on the Coefficient Method (FEMA 356) is also examined. Results in terms of failure modes, capacity curves, interstory drifts, ductility requirements and infills behaviour are presented. From the results it can be deduced that the global capacity of the structures is decreased due to the considered first floor morphology irregularities in comparison to the capacities of the regular structure. An increase of the demands for interstory drift is observed at the first floor level due to the considered irregularities while the open ground floor structure (pilotis type) led to even higher values of interstory drift demands at the first story. In the cases of tall first story and slab-column connections without beams soft-story mechanisms have also been observed at the first floor. Rotational criteria (EC8-part3) showed that the structure with slab-column connections without beams exhibited the most critical response.

Efficiency of various structural modeling schemes on evaluating seismic performance and fragility of APR1400 containment building

  • Nguyen, Duy-Duan;Thusa, Bidhek;Park, Hyosang;Azad, Md Samdani;Lee, Tae-Hyung
    • Nuclear Engineering and Technology
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    • v.53 no.8
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    • pp.2696-2707
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    • 2021
  • The purpose of this study is to investigate the efficiency of various structural modeling schemes for evaluating seismic performances and fragility of the reactor containment building (RCB) structure in the advanced power reactor 1400 (APR1400) nuclear power plant (NPP). Four structural modeling schemes, i.e. lumped-mass stick model (LMSM), solid-based finite element model (Solid FEM), multi-layer shell model (MLSM), and beam-truss model (BTM), are developed to simulate the seismic behaviors of the containment structure. A full three-dimensional finite element model (full 3D FEM) is additionally constructed to verify the previous numerical models. A set of input ground motions with response spectra matching to the US NRC 1.60 design spectrum is generated to perform linear and nonlinear time-history analyses. Floor response spectra (FRS) and floor displacements are obtained at the different elevations of the structure since they are critical outputs for evaluating the seismic vulnerability of RCB and secondary components. The results show that the difference in seismic responses between linear and nonlinear analyses gets larger as an earthquake intensity increases. It is observed that the linear analysis underestimates floor displacements while it overestimates floor accelerations. Moreover, a systematic assessment of the capability and efficiency of each structural model is presented thoroughly. MLSM can be an alternative approach to a full 3D FEM, which is complicated in modeling and extremely time-consuming in dynamic analyses. Specifically, BTM is recommended as the optimal model for evaluating the nonlinear seismic performance of NPP structures. Thereafter, linear and nonlinear BTM are employed in a series of time-history analyses to develop fragility curves of RCB for different damage states. It is shown that the linear analysis underestimates the probability of damage of RCB at a given earthquake intensity when compared to the nonlinear analysis. The nonlinear analysis approach is highly suggested for assessing the vulnerability of NPP structures.