• 한국가스학회지
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• 제14권6호
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• pp.44-50
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• 2010

내진 평가에서 동적 해석이 필요한 원심펌프에 대하여, 시간 이력 해석에 비해 간편한 스펙트럼 해석을 이용하여, 진동 응답을 산출하였다. 유한요소법에 의하여 모드 해석을 하였으며, 모드 해석 결과에 입각하여 스펙트럼 해석을 수행하였다. 스펙트럼 해석에 의해 구해진 진동 응답은 시간 이력 해석의 결과보다 보수적으로 산출되어 안전하게 설계할 수 있음을 알 수 있었다. 본 연구에서의 펌프는 IEEE 344-1987에서 요구되는 조건에 따라 내진 구조 건전성이 평가 되었다. 각 부재의 최대 응력은 허용 응력이하로 산출되었으며, 펌프는 주어진 지진 입력에 대하여 요구되는 안전 조건을 구비하고 있음이 판명되었다.

• 한국안전학회지
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• 제24권2호
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• pp.55-61
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• 2009

Seismic Safety Analysis of Intake Tower is very important because failure of intake tower may incur huge chaos on the modem society. Recently, there has been growing much concern about earthquake resistance of existing structures. This research demonstrates the dynamic fluid pressure calculation using added mass simulation. The actual safety evaluation has been conducted through not only the static analysis but also the dynamic analysis. According to the analysis results, the vibration incurred by earthquake may induce considerable damage to the hydraulic structure. Therefore, the appropriate design process out of exact calculation is quite necessary.

• Earthquakes and Structures
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• 제13권6호
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• pp.531-538
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• 2017

In this paper, the seismic behavior of BRBF structures is studied and compared with special concentric braced frames (SCBF). To this purpose, three BRBF and three SCBF structures with 3, 5 and 10 stories are designed based on AISC360-5 and modelled using OpenSees. These structures are loaded in accordance with ASCE/SEI 7-10. Incremental nonlinear dynamic analysis (IDA) are performed on these structures for 28 different accelerograms and the median IDA curves are used to compare seismic capacity of these two systems. Results obtained, indicates that BRBF systems provide higher capacity for the target performance level in comparison with SCBF systems. And structures with high altitude (in this study, 5 and 10 stories) with the possibility of exceeding the collapse prevention performance level, further than lower altitude (here 3 floors) structures.

• Steel and Composite Structures
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• 제46권5호
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• pp.621-635
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• 2023

The combination of replaceable and repairable properties in structures has introduced new approach called "Low Damage Design Structures". These structural systems are designed in such a way that through self-centering, primary members and specific connections neither suffer damage nor experience permanent deformations after being exposed to severe earthquakes. The purpose of this study is the seismic assessment of steel moment resisting frames with the aid of rigid rocking cores. To this end, three steel moment resisting frames of 4-, 8-, and 12-story buildings with and without rocking cores were developed. The nonlinear static analysis and incremental dynamic analysis were performed by considering the effects of the vertical and horizontal components of 16 strong ground motions, including far-fault and near-fault arrays. The results reveal that rocking systems benefit from better seismic performance and energy dissipation compared to moment resisting frames and thus structures experience a lower level of damage under higher intensity measures. The analyses show that the interstory drift in structures equipped with stiff rocking cores is more uniform in static and dynamic analyses. A uniform interstory drift distribution leads to a uniform distribution of the bending moment and a reduction in the structure's total weight and future maintenance costs.

• 대한토목학회논문집
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• 제10권2호
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• pp.103-112
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• 1990

본 연구는 내진설계시 많은 불확실성을 내포하는 지반의 거동특성을 규명하고, 적용대상지반의 확충 및 경제성 제고를 위하여 토사지반의 동적지반특성 평가 및 지반-구조물 거동 특성을 고찰하였다. 예제해석은 토사지반에 원전 containment 구조물이 설치된 경우를 가상하여 지진하중에 대한 지반-구조물 시스템의 거동을 반무한체해석과 유한요소해석으로 분석하였다. 이는 토사지반에 원전이 건설될 경우에 고려해야 할 안정성 및 경제성 분석의 일환으로 수행되었으며, 토사지반의 큰 비선형거동을 정확하게 해석에 반영하기 위한 해석 software와 지반입력 data의 합리적인 평가방안 등을 예제해석을 통하여 분석하였다. 예제해석결과를 종합해 볼 때 토사지반의 동적거동의 정확한 분석을 위하여 비선형 유한요소해석은 Seed & Idriss 모델이, 선형 유한요소해석은 지진하중에 대한 1차원 지반거동시 변형율에서의 동적지반특성을 이용한 방법이, 반무한체해석은 정적하중시 변형율에서의 동적지반특성을 이용한 방법이 가장 합리적으로 동적지반특성을 평가하는 것으로 추천할 수 있다.

• 한국지진공학회논문집
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• 제10권1호
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• pp.63-74
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• 2006

원전 구조물 및 주요기기의 지진 안전성 평가에서는 내진성능을 정량화하는 방법으로 취약도 분석이 사용되고 있다. 지진취약도 분석은 격납건물의 설계 시 반영된 보수성을 배제한 실질적인 내진성능을 평가하는 것으로 이러한 보수성을 성능 및 응답에 관련된 확률론적 변수로 고려하여 평가하게 된다. 본 연구에서는 비선형 지진 해석으로부터 얻은 구조물의 변위응답을 기초로 한 지진취약도 분석 방법을 제시하였다. 또한 원전부지에서 선정된 발생가능한 근거리지진, 원거리지진, 설계지진 및 확률론적 시나리오지진을 시나리오지진으로 선정하고 이들 지진동에 대한 비선형 지진해석을 통하여 한국 표준형 원전 격납건물의 지진취약도를 평가하였다.

• 지구물리
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• 제6권2호
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• pp.89-97
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• 2003

For safety evaluation of a rockfill dam, it is often necessary to investigate spatial distribution and dynamic characterization of weak zones such as fractures. For this purpose, both seismic and electric methods are adopted together in this research. The former employs the multichannel analysis of surface waves (MASW) method, and aims at the mapping of 2-D shear-wave velocity (Vs) profile along the dam axis that can be associated with dynamic properties of filled materials. The latter is carried out by DC- resistivity survey with a main purpose of mapping of spatial variations of physical properties of dam materials. Results from both methods are compared in their signature of anomalous zones. In addition, downhole seismic survey was carried out at three points within the seismic survey lines and results by downhole seismic survey are compared with the MASW results. We conclude that the MASW is an efficient method for dynamic characterization of dam-filling materials, and also that joint analyses of these two seemingly unrelated methods can lead to an effective safety evaluation of rock-fill dam.

• Geomechanics and Engineering
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• 제6권6호
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• pp.561-575
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• 2014

Estimating seismic displacements has a great importance for foundations on or adjacent to slope surfaces. However, dynamic solution of the problem has received little attention by previous researchers. This paper presents a new analytical model to determine seismic displacements of the shallow foundations adjacent to slopes. For this purpose, a dynamic equilibrium equation is written for the foundation with failure wedge. Stiffness and damping at the sliding surface are considered variable and a simple method is proposed for its estimation. Finally, for different failure surfaces, the calculated dynamic displacement and the surfaces with maximum strain are selected as the critical failure surface. Analysis results are presented as curves for different slope angles and different foundation distances from edge of the slope and are then compared with the experimental studies and software results. The comparison shows that the proposed model is capable of estimating seismic displacement of the shallow foundations adjacent to slopes. Also, the results demonstrate that, with increased slope angle and decreased foundation distances from the slope edge, seismic displacement increases in a non-linear trend. With increasing the slope angle and failure wedge angle, maximum strain of failure wedge increases. In addition, effect of slope on foundation settlement could be neglected for the foundation distances over 3B to 5B.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.169-176
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• 2002

It was performed that the seismic response analysis using seismic magnitude and concrete dam type(Model-1, Model-2) on dynamic behavior properties of concrete dam. As a results of each seismic magnitude acted on concrete dam, the maximum response acceleration at dam crest was amplified about 3, 5-4 times and maximum displacement and stress at dam crest of Model-2 was larger than Model-1. So, it can be recommended that codified-seismic coefficient method is proper in case of seismic design of concrete dam and Model-1 is better than Model 2 in consideration of stability in displacement and stress of design of concrete dam.

• Computers and Concrete
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• 제25권3호
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• pp.273-282
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• 2020

A new seismic design methodology for precast concrete diaphragms has been developed and incorporated into the current American seismic design code. This design methodology recognizes that diaphragm inertial forces during earthquakes are highly influenced by higher dynamic vibration modes and incorporates the higher mode effect into the diaphragm seismic design acceleration determination using a first mode reduced method, which applies the response modification coefficient only to the first mode response but keeps the higher mode response unreduced. However the first mode reduced method does not consider effects of diaphragm flexibility, which plays an important role on the diaphragm seismic response especially for the precast concrete diaphragm. Therefore this paper investigated the effect of diaphragm flexibility on the diaphragm seismic design acceleration for precast concrete shear wall structures through parametric studies. Several design parameters were considered including number of stories, diaphragm geometries and stiffness. It was found that the diaphragm flexibility can change the structural dynamic properties and amplify the diaphragm acceleration during earthquakes. Design equations for mode contribution factors considering the diaphragm flexibility were first established through modal analyses to modify the first mode reduced method in the current code. The modified first mode reduced method has then been verified through nonlinear time history analyses.