• 한국지진공학회논문집
• /
• 제2권2호
• /
• pp.23-34
• /
• 1998

본 논문은 바닥판을 고려한 3차원 골조 구조물의 효율적인 연직 진동 해석법을 제안한다. 바닥판의 영향을 고려하면 구조물의 진동해석을 좀더 정확히 수행할 수 있는 반면, 면요소의 사용에 따른 많은 자유도의 사용으로 많은 해석시간과 기억용량이 필요하게 된다. 따라서, 행렬응축기법을 사용하여 적절한 요소분할 및 주자유도 선택 기법을 제안하였으며, 대형요소를 사용하여 정확화된 일반적인 건물의 동적해석에 적용하여 입력 데이터의 작성을 간단히 하고 동적해석을 빠르고 신뢰할 만한 결과를 얻을 수 있는 기법에 대하여 연구하였다.

• 한국지반환경공학회 논문집
• /
• 제19권7호
• /
• pp.5-11
• /
• 2018

Instead of a single pile, group piles are usually used for the pile foundation. If the earthquake occurs in the ground where group piles are installed, dynamic behavior of group piles are affected not only by interaction of piles and the ground movement but also by the pile cap. However, in Korea, the pile cap influence is not taken account into the design of group piles. Research on dynamic behavior of group piles has been performed only to verify interaction of piles and the ground and has not considered the pile cap as a factor. In this research, 1g shaking table model tests were performed to verify the thickness of the pile cap affects dynamic behavior of group piles that were installed in the ground where the earthquake would occur. The test results show that, as thickness of the pile cap increased, acceleration and horizontal displacement of the pile cap decreasd while vertical displacement of the pile cap increased. The results also showed that, among the group files tested, acceleration, horizontal displacement, and vertical displacement of the bearing pile are smaller than those of the friction pile.

• 한국지진공학회논문집
• /
• 제8권6호통권40호
• /
• pp.1-11
• /
• 2004

이전의 연구(1)에서는 해석적 및 수치적 방법을 사용하여 전단변형 및 회전관성효과를 고려하는 현수교의 수직진동에 대하여 유한요소법을 이용하여 이동하중 해석을 수행하였다. 본 연구에서는 전단변형 및 회전관성 효과가 고려된 Hermitian 다항식을 사용하는 현수교요소를 이용하여 현수교의 수직진동에 대한 고유치 해석을 수행하고 이를 이용한 현수교요소와 차량 및 열차와의 상호작용을 고려한 운동방정식을 유도한다. 이와 같이 모드중첩법을 이용하여 유도된 운동방정식을 수치적분방법으로 Newmark $\beta$ Method를 사용하여 동적해석을 수행하였다.

• 한국지진공학회논문집
• /
• 제28권5호
• /
• pp.257-266
• /
• 2024

Due to seismically deficient details, existing reinforced concrete structures have low lateral resistance capacities. Since these building structures suffer an increase in axial loads to the main structural element due to the green retrofit (e.g., energy equipment/device, roof garden) for CO₂ reduction and vertical extension, building capacities are reduced. This paper proposes a machine-learning-based methodology for allowable ranges of axial loading ratio to reinforced concrete columns using simple structural details. The methodology consists of a two-step procedure: (1) a machine-learning-based failure detection model and (2) column damage limits proposed by previous researchers. To demonstrate this proposed method, the existing building structure built in the 1990s was selected, and the allowable range for the target structure was computed for exterior and interior columns.

• 농업과학연구
• /
• 제50권3호
• /
• pp.511-526
• /
• 2023

In this study, three types of structures-stepped gabion retaining walls, vertical gabion retaining walls, and parapets-were installed on the dam floor crest to prevent the overflow of deteriorative homogeneous reservoirs. The acceleration response, displacement behavior, and pore water pressure ratio behavior were compared and evaluated using shaking-table model tests. The experimental conditions were set to 0.154 g in consideration of the domestic standard and the seismic acceleration range according to the magnitude of the earthquake, and the input waveform was applied with Pohang, Gongen, and artificial earthquake waves. The acceleration response according to the design ground acceleration increased as the height of the embankment increased, and the observed value were larger in the range of 1.1 to 2.1 times the input acceleration for all structures. The horizontal and vertical displacements exhibited maximum values on the upstream slope, and the embankment was evaluated as stable and included within the allowable range for all waveforms. The settlement ratio considering the similarity law exhibited the least change in the case of the parapet structure. The amplification ratio was 1.1 to 1.5 times in all structures, with the largest observed in the dam crest. The maximum excess pore water pressure ratio was in the range of 0.010 - 0.021, and the liquefaction evaluation standard was within 1.0, which was considered very stable.

• Nuclear Engineering and Technology
• /
• 제48권5호
• /
• pp.1237-1251
• /
• 2016

Although the horizontal component of an earthquake response can be significantly reduced through the use of conventional seismic isolators, the vertical component of excitation is still transmitted directly into the structure. Records from instrumented structures, and some recent tests and analyses have actually seen increases in vertical responses in base isolated structures under the combined effects of horizontal and vertical ground motions. This issue becomes a great concern to facilities such as a Nuclear Power Plants (NPP), with specialized equipment and machinery that is not only expensive, but critical to safe operation. As such, there is considerable interest worldwide in vertical and three-dimensional (3D) isolation systems. This paper examines several vertical and 3D isolation systems that have been proposed and their potential application to modern nuclear facilities. In particular, a series of case study analyses of a modern NPP model are performed to examine the benefits and challenges associated with 3D isolation compared with horizontal isolation. It was found that compared with the general horizontal isolators, isolators that have vertical frequencies of no more than 3 Hz can effectively reduce the vertical in-structure responses for the studied NPP model. Among the studied cases, the case that has a vertical isolation frequency of 3 Hz is the one that can keep the horizontal period of the isolators as the first period while having the most flexible vertical isolator properties. When the vertical frequency of isolators reduces to 1 Hz, the rocking effect is obvious and rocking restraining devices are necessary.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
• /
• pp.121-127
• /
• 2001

To investigate the stability and integrity of offshore structures, it is necessary to estimates the significant ocean environmental loadings. They include hydrostatic pressure, wind, wave, current, tide, ice, earthquake, temperature, marine growth and scouring. Waves are of major importance among them because of the large forces acting on submerged parts of the structure caused by accompanying water motions. For the comparison of stress and deflection analysis tools, a vertical pile is applied under environmental loads. The analysis is concerned with SACS(Structural Analysis Computer System), ANSYS and C program. SACS and C program have nearly the same results but not ANSYS. This study shows the comparison of results obtained from 3 different approaches.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1997년도 가을 학술발표회 논문집
• /
• pp.279-286
• /
• 1997

The objective of this paper is to investigate the effects of the rocking motion and the vertical natural frequency of a seismically isolated structure using LRBs. The governing equations of motion of the rigid body structure, which consider a large rocking motion, are derived. For the mathematical model of LRB, the horizontal stiffness equation based on Haringx's theory is used. From this paper, as decreasing the vertical natural frequency, the rocking responses increase and the horizontal isolation frequency and its earthquake responses are severely affected.

• Earthquakes and Structures
• /
• 제20권3호
• /
• pp.239-260
• /
• 2021

Torsional response of buildings is attributed to poor structural configurations in plan, which arises due to two factors - torsional eccentricity and torsional flexibility. Usually, building codes address effects due to the former. This study examines both of these effects. Buildings with torsional eccentricity (e.g., those with large eccentricity) and with torsional flexibility (those with torsional mode as a fundamental mode) demand large deformations of vertical elements resisting lateral loads, especially those along the building perimeter in plan. Lateral-torsional responses are studied of unsymmetrical buildings through elastic and inelastic analyses using idealised single-storey building models (with two degrees of freedom). Displacement demands on vertical elements distributed in plan are non-uniform and sensitive to characteristics of both structure and earthquake ground motion. Limits are proposed to mitigate lateral-torsional effects, which guides in proportioning vertical elements and restricts amplification of lateral displacement in them and to avoid torsional mode as the first mode. Nonlinear static and dynamic analyses of multi-storey buildings are used to validate the limits proposed.

• 한국공간구조학회논문집
• /
• 제9권1호
• /
• pp.87-94
• /
• 2009

본 논문은 지진하중에 대한 복층 배럴볼트 시스템의 동적거동을 조사한 것이다. 시간이력해석에 따른 지진에 대한 거동을 조사하기 위하여 6개의 다른 개각과 각 개각에 대하여 0.5초 간격으로 4개의 추가적인 고유 진동수가 고려되었다. 전체 24개의 해석모델들이 컴퓨터 해석 프로그램인 MIDAS Gen.에 의해 설계되었고 5%의 감쇠비가 고려된 3개의 지진에 대하여 시간이력해석이 수행되었다. 지진이 적용될 때 수평방향에 대한 응답반응만 고려하는 라멘 구조물과는 달리 대공간 구조물의 경우 수평방향 뿐만 아니라 상하 방향의 동적거동을 고려하는 것이 중요하다. 따라서 본 연구에서는 수평방향 지진(H)과 수직방향 지진(V)에 대하여 X-, Y- 그리고 Z- 방향에 대한 동적거동 특성에 대하여 평가하였다. 개각과 진동수에 따른 동적거동 특성을 파악하기 위하여 최대 응답이 나타나는 시간에서 배럴볼트 시스템의 특정 절점들에 대한 가속도 응답비를 살펴보았다. 본 논문에서 동적거동을 조사한 가장 중요한 목적은 본 연구의 최종 목적인 배럴볼트시스템에 대한 등가정적지진력을 구하는 식을 제안하기 위함이다.