• 한국공간구조학회논문집
• /
• 제20권4호
• /
• pp.169-176
• /
• 2020

When an unexpected excessive seismic load is applied to the base isolation of arch structure, the seismic displacement of the base isolation may be very large beyond the limit displacement of base isolation. These excessive displacement of the base isolation causes a large displacement in the upper structure and large displacement of upper structure causes structural damage. Therefore, in order to limit the seismic displacement response of the base isolation, it is necessary to install an additional device such as an anti-uplift device to the base isolation. In this study, the installation direction of the base isolation and the control performance of the base isolation installed anti-uplift device were investigated. The installation direction of the base isolation of the arch structure is determined by considering the horizontal and vertical reaction forces of the arch structure. In addition, the separation distance of the anti-uplift device is determined in consideration of the design displacement of the base isolation and the displacement of the arch structure.

• Smart Structures and Systems
• /
• 제28권6호
• /
• pp.827-838
• /
• 2021

The dynamic displacement is considered to be an important indicator of structural safety, and becomes an indispensable part of Structural Health Monitoring (SHM) system for high-speed railway bridges. This paper proposes an indirect strain based dynamic displacement reconstruction methodology for high-speed railway box girders. For the typical box girders under eccentric train load, the plane section assumption and elementary beam theory is no longer applicable due to the bend-torsion coupling effects. The monitored strain was decoupled into bend and torsion induced strain, pre-trained multi-output support vector regression (M-SVR) model was employed for such decoupling process considering the sensor layout cost and reconstruction accuracy. The decoupled strained based displacement could be reconstructed respectively using box girder plate element analysis and mode superposition principle. For the transformation modal matrix has a significant impact on the reconstructed displacement accuracy, the modal order would be optimized using particle swarm algorithm (PSO), aiming to minimize the ill conditioned degree of transformation modal matrix and the displacement reconstruction error. Numerical simulation and dynamic load testing results show that the reconstructed displacement was in good agreement with the simulated or measured results, which verifies the validity and accuracy of the algorithm proposed in this paper.

• Wind and Structures
• /
• 제36권6호
• /
• pp.379-392
• /
• 2023

Structural health monitoring is used to ensure the well-being of civil structures by detecting damage and estimating deterioration. Wind flow applies external loads to high-rise buildings, with the horizontal force component of the wind causing structural displacements in high-rise buildings. This study proposes a deep learning-based predictive model for measuring lateral displacement response in high-rise buildings. The proposed long short-term memory model functions as a sequence generator to generate displacements on building floors depending on the displacement statistics collected on the top floor. The model was trained with wind-induced displacement data for the top floor of a high-rise building as input. The outcomes demonstrate that the model can forecast wind-induced displacement on the remaining floors of a building. Further, displacement was predicted for each floor of the high-rise buildings at wind flow angles of 0° and 45°. The proposed model accurately predicted a high-rise building model's story drift and lateral displacement. The outcomes of this proposed work are anticipated to serve as a guide for assessing the overall lateral displacement of high-rise buildings.

• Computers and Concrete
• /
• 제33권5호
• /
• pp.481-496
• /
• 2024

Internal erosion around pipes can lead to the failure of earth dams through various mechanisms. This study investigates the displacement patterns in earth dam models under three different failure modes due to internal erosion, using digital image correlation (DIC) methods. Three failure modes—erosion along a pipe (FM1), pipe leakage leading to soil erosion (FM2), and erosion in a pipe due to defects (FM3)—are analyzed using two- and three-dimensional image- processing techniques. The internal displacement of the cross-sectional area and the surface displacement of the downstream slope in the dam models are monitored using an image acquisition system. Physical model tests reveal that FM1 exhibits significant displacement on the upper surface of the downstream slope, FM2 shows focused displacement around the pipe defect, and FM3 demonstrates increased displacement on the upstream slope. The variations in internal and surface displacements with time depend on the segmented area and failure mode. Analyzing the relationships between internal and surface displacements using Pearson correlation coefficients reveals various displacement patterns for the segmented areas and failure modes. Therefore, the image-based characterization methods presented in this study may be useful for analyzing the displacement distribution and behavior of earth dams around pipes, and further, for understanding and predicting their failure mechanisms.

• 대한토목학회논문집
• /
• 제28권4A호
• /
• pp.507-515
• /
• 2008

본 연구에서는 모드분해기법을 이용한 변형률신호로부터 변위응답추정 방법을 개발하였다. 일반적으로 교량의 안정성평가는 완공 후에 초점이 맞추어져 있다. 하지만 가설 중에도 풍하중과 지진하중과 같은 동적하중에 노출되어 있으며, 이런 동적하중에 대한 안정성을 검토하기 위해 교량의 안정성 평가에 있어 중요한 인자인 변위를 추정하는 것이 중요하다. 그러나 건설현장에서의 적절한 변위측정 방법의 부재로 인하여 대형구조물의 전체적인 변위를 측정할 수 없는 것이 현실이다. 본 연구에서는 간접적으로 변위를 추정하는 방법인 변형률로 변위를 추정하는 방법을 제시하였으며, 광섬유 브래그 격자 센서(fiber optic Bragg-grating sensor)를 사용하여 변형률을 계측하였다. 기존에도 FBG센서를 이용한 변위추정 방법이 있었으며 기존의 방법으로는 정적하중에 대한 변위추정은 가능하였으나 고차 모드의 변형률신호와 노이즈의 영향 때문에 동적하중에 대한 변위추정은 많은 오차가 발생하여 정확한 변위추정이 어려웠다. 이런 오차를 줄이는 방법으로 모드분해기법을 사용하였다. 모드분해기법은 변형률신호로부터 proper orthogonal decomposition(POD)을 이용하여 추정한 모드형상과 empirical mode decomposition(EMD)을 이용하여 모드 분해한 변형률신호로 모드별 변위응답을 추정하고, 구조물의 주요 모드에 대한 변위응답을 합하여 전체변위응답을 추정하는 방법이다. 제안한 모드분해기법을 검증하기 위해 실내모형실험을 수행하였다.

• 한국건설순환자원학회논문집
• /
• 제11권4호
• /
• pp.355-363
• /
• 2023

노후 교량의 안전성을 평가하는 방법에 있어서 동특성과 처짐은 구조계의 강성과 직접 연관이 있으며, 처짐의 경우에는 교량 사용자가 직접 감지할 수 있는 물리량으로 가장 중요한 인자이다. 하지만 교량의 처짐을 측정하기 위해서는 교량의 하부에 처짐계를 설치하고 교통 차단 및 재하시험을 실시해야 하는 번거로움이 있어 교량의 환경에 따라서 비용이 증가하거나 측정이 불가능한 문제들이 발생하고 있다. 본 연구에서는 처짐계의 설치 없이 가속도계만을 이용하고 재하시험 없이 상시 진동을 이용하여 교량의 처짐을 측정하는 방법을 제안하였다. 상시 진동을 이용한 교량 동특성 및 처짐 분석을 위해 단순한 연산으로 빠른 분석이 가능하다고 알려진 TDD 기법을 이용하여 교량의 모드형상과 고유진동수를 추출하였으며, 유연도 분석을 통하여 교량의 단위하중 처짐을 분석하여 정적 처짐까지 산정하였다. 본 제안 기술의 검증을 위해 공용중 교량인 C대교(사장교)에 적용하여 모드형상, 고유진동수, 정적 처짐 분석을 수행하였으며 재하시험 실측값과 구조해석 자료와 비교하였다. 그 결과 모드형상 및 고유진동수는 0.42~1.13 %, 중앙경간에서의 최대 처짐은 3.58 %의 오차율을 확인하였다. 따라서 제안기술은 처짐계의 설치가 어려워 실측이 불가능한 교량의 처짐을 추정하여 설계값 및 해석값 대비 처짐 발생량 비교로 교량의 안전성을 간접적으로 파악할 수 있는 근거 자료로 활용 가능할 것으로 사료된다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 추계 학술발표회 2차
• /
• pp.181-185
• /
• 2010

Until now, design of Earth Retaining is practiced by 2 dimensional analysis for convenience of analysis and time saving. However, the construction field is 3 dimension, in this study, practised the 3 dimensional analysis which can reflect the field condition more exactly the scope of earth retaining wall, and researched about the effective and economical way of design, compared and reviewed with the results, by practising both the 2 and 3 dimensional analysis. existing 2 dimension. the depth of excavation, depth of embedded and soil condition. As result, under the whole conditions, more displacement came to appear to the value as result of 3 dimensional analysis more than the result of 2nd dimensional analysis. Accordingly, the displacement by the 2 dimension analysis is underestimated. Moreover, results of 2 and 3 dimensional analysis, there is no difference at displacement, when the depth of embedded is 0.5H and 1.0H, but Displacement of 1.5H is smaller than 0.5H, 1.0H. That is, the bigger the depth of embedded becomes, the displacement of Earth Retaining Wall appeared smaller. The displacement of earth retaining wall according to depth of excavation appeared bigger, when the depth of excavation is increased. In the meantime, when the soil condition is different, in the 2 dimensional analysis, the displacement appeared biggest, in case of the clay layer, but in the 3 dimensional analysis, in the beginning of excavating, the displacement of earth retaining wall appeared bigger in case of clay layer, but as excavating is in progress, the displacement of both compound soil layer and sand layer appeared big.

• 한국전문물리치료학회지
• /
• 제12권1호
• /
• pp.11-21
• /
• 2005

The purpose of this study was to investigate how COP displacement of a hemiplegic foot in stance phase during gait is related to clinical balance measures and the recovery stage in hemiplegic stroke patients. Twenty-eight functionally ambulant hemiplegic patients who had suffered from strokes and thirty age-matched healthy subjects participated in this study. COP parameters were calculated. Clinical balance was measured using the Functional Reach Test (FRT) and Timed Up and Go Test (TUGT). The recovery stage, proprioception, and clonus of the ankles or lower extremities were also measured for physical impairment status. The COPx max-displacement in the medial-lateral side of the stroke patients was significantly longer than that of the normal group (p=.038). The COPy max-displacement in the anterior-posterior side of the stroke patients was significantly shorter than that of normal group (p<.001). Significant differences in the COPx and COPy displacement asymmetry index were found between the two groups (p<.01). The FRT was correlated with the COPx displacement (r=.552) and COPy displacement (r=.765). The TUGT was correlated with the COPy displacement (r=-.588) only. The recovery stage of the lower extremities was correlated with COPy displacement (r=.438). The results of the study indicate that the characteristic of COP displacement in hemiplegic feet in stance phase during gait is related to balance ability and recovery in stroke patients. COP parameters acquired by the mapping of foot pressure in stance phase during gait will provide additional useful clinical information. This information can be used by clinicians to assess objectively the pathologic gait with other diseases and to evaluate the therapeutic effects on gait in stroke patients.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
• /
• pp.190-197
• /
• 2005

To monitor the safety and serviceability of a structures, structural responses including displacements due to various design and unexpected loadings must be measured. The maximum displacement and its distributions of a structure can be used as a direct assessment index on its stiffness. For this reason, there have been diversely studied on measuring of the maximum displacement of a structure. However, there is no practical method for measuring displacement of a structure. Therefore, in this paper, new displacement measuring method is developed and accuracy of LiDAR is examined in detail for development of a new method for measuring displacement of a structure.

• 대한치과보철학회지
• /
• 제36권1호
• /
• pp.18-25
• /
• 1998

The purpose of this study was to determine how to use soft relining material by observing an amount of denture displacement according to the different base area of residual ridge and thickness of soft relining material under masticatory force. Stone models that simulated residual ridge were made with different amount of denture base area and denture was fabricated by conventional heat curing resin with usual manner on the model and relined by silicone type soft relining material with different thickness. Specimen was examined the amount of denture displacement by Instron within range of normal occlusal force. The results were as following : 1. The increasing rate of denture displacement was higher than that of soft relining material thickness. 2. The amount of denture displacement decreased 1.7 times when base area became double at same thickness of soft relining material 3. The increasing rate of denture displacement was higher than that of occlusal force