• 한국철도학회논문집
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• 제9권1호
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• pp.12-17
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• 2006

The bridge to be analyzed is a self-anchored suspension bridge which is constructed within the country. Forced vibration test was performed with oscillator for verification of safety, maintenance and management. In this study, the feasibility of deduction was verified with the modified analysis model by comparing natural frequency, natural mode and damping ratio of the real bridge, which are obtained from the vibration test of the whole bridge after construction of 3-dimensional self-anchored cable suspension bridge, with the eigenvalue of analytic computation model and evaluating them. As a result of study, the friction of bridge bearing must be considered to get the natural frequencies of flexural vibration, and evaluating the polar moment of inertia is critical factor in analysis modeling in case of torsional vibration. The logarithmic damping ratio of the test appeared to exceed the ordinary one assumed at the design phase.

• 한국안전학회지
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• 제27권1호
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• pp.44-48
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• 2012

The seismic safety of long-period cable-stayed bridges is assessed by probabilistic finite element analysis and reliability analysis under NFE. The structural response of critical members of cable-stayed bridges is evaluated using the developed probabilistic analysis algorithm. In this study, the real earthquake recording(Chi-Chi Earthquake; 1997) was selected as the input NFE earthquake for investigating response characteristics. The probabilistic response and reliability index shows the different aspect comparing the result from FFE earthquake. Therefore, the probabilistic seismic safety assessment on NFE earthquakes should be performed for the exact evaluation of long-period cable-stayed bridges and the earthquake resistant design criteria should be complemented.

• Wind and Structures
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• 제8권2호
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• pp.135-146
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• 2005

Divergent galloping-like motion of a dry inclined cable has been observed in a limited number of experimental studies, which, due to the uncertainties in its onset conditions, has induced serious concerns in the bridge stay cable design. A series of dynamic and static model wind tunnel tests have been carried out to confirm the existence of the phenomenon and clarify its excitation mechanism. The present paper focuses on exploring the spatial flow structure around an inclined cable. The pattern of resultant aerodynamic forces acting at different longitudinal locations of the model and the spatial correlation of the forces are examined. The results lead one step closer in revealing the physical nature of the phenomenon.

• Smart Structures and Systems
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• 제24권1호
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• pp.83-94
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• 2019

Passive negative stiffness dampers (NSDs) that possess superior energy dissipation abilities, have been proved to be more efficient than commonly adopted passive viscous dampers in controlling stay cable vibrations. Recently, inertial mass dampers (IMDs) have attracted extensive attentions since their properties are similar to NSDs. It has been theoretically predicted that superior supplemental damping can be generated for a taut cable with an IMD. This paper aims to theoretically investigate the impact of the cable sag on the efficiency of an IMD in controlling stay cable vibrations, and experimentally validate superior vibration mitigation performance of the IMD. Both the numerical and asymptotic solutions were obtained for an inclined sag cable with an IMD installed close to the cable end. Based on the asymptotic solution, the cable attainable maximum modal damping ratio and the corresponding optimal damping coefficient of the IMD were derived for a given inertial mass. An electromagnetic IMD (EIMD) with adjustable inertial mass was developed to investigate the effects of inertial mass and cable sag on the vibration mitigation performance of two model cables with different sags through series of first modal free vibration tests. The results show that the sag generally reduces the attainable first modal damping ratio of the cable with a passive viscous damper, while tends to increase the cable maximum attainable modal damping ratio provided by the IMD. The cable sag also decreases the optimum damping coefficient of the IMD when the inertial mass is less than its optimal value. The theoretically predicted first modal damping ratio of the cable with an IMD, taking into account the sag generally, agrees well with that identified from experimental results, while it will be significantly overestimated with a taut-cable model, especially for the cable with large sag.

• Wind and Structures
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• 제19권5호
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• pp.481-503
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• 2014

A new theoretical model on rain-wind induced vibration (RWIV) of a continuous stay cable is developed in this paper. Different from the existing theoretical analyses in which the cable was modeled as a segmental rigid element, the proposed scheme focuses on the in-plane and out-of-plane responses of a continuous stay cable, which is identical with the prototype cable on cable-stayed bridge. In order to simplify the complexities, the motion law of the rivulet on the cable surface is assumed as a sinusoidal way according to some results obtained from wind tunnel tests. Quasi-steady theory is utilized to determine the aerodynamic forces on the cable. Equations of motion of the cable are derived in a Cartesian Coordinate System and solved by using finite difference method to obtain the in-plane and out-of-plane responses of the cable. The results show that limited cable amplitudes are achieved within a limited range of wind velocity, which is a unique characteristic of RWIV of stay cable. It appears that the in-plane cable amplitude is much larger than the out-of-plane cable amplitude. Rivulet frequency, rivulet distribution along cable axis, and mean wind velocity profile, all have significant effects on the RWIV responses of the prototype stay cable. The effects of damping ratio on RWIVs of stay cables are carefully investigated, which suggests that damping ratio of 1% is needed to well mitigate RWIVs of prototype stay cables.

• 한국방재안전학회논문집
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• 제15권3호
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• pp.79-88
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• 2022

특수교는 중요한 대형 시설물로 장기적이고 체계적인 유지관리 전략을 필요로 한다. 특히, 시설물 부재별 및 위치별로 다양한 센서를 설치하고 계측 항목별 관리 기준치 설정과 같은 시설물의 안전 확보를 위해 여러 방안들이 제시되고 있다. 이 중 지속적으로 증가하는 특수교의 수와 여러 센서에서 수집되는 데이터를 효율적으로 관리하기 위한 전략적인 방안을 제시해야 할 필요가 있다. 본 연구에서는 특수교 계측 시스템에서 수집되는 광범위한 데이터를 효율적으로 분석하기 위한 목적으로 자동적으로 이상신호를 처리하고 통계 결과를 산출할 수 있는 분석 툴을 개발하고자 한다. 분석 툴 개발을 위해 우선 특수교에 설치된 주요 센서 종류 및 수량과 같은 기본적인 정보와 수집된 데이터에 대한 신호 특성을 분석하였다. 이후 험펠 필터 기법을 활용 신호의 이상 유무를 판별하고 필터링하여 통계 결과를 산출하였다. 마지막으로 개발된 분석 툴의 성능 검증을 위해 현재 공용 중인 사장교와 현수교 형식의 교량을 각 1개소씩 성능검증 대상 교량으로 선정하여 신호처리 및 자동 통계 분석 성능을 실시하였고, 기존의 통계 작업 결과와 유사한 결과를 산출 할 수 있었다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.253-258
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• 2007

Guss asphalt used in pavement of a steel deck bridge may cause severe stress and displacement on the bridge as it is treated using very high temperatures ranging from $220^{\circ}C$ to $260^{\circ}C$. Therefore, it is critical to estimate the thermal effect of Guss asphalt on the steel deck bridge before the width and pattern of the unit portion are decided to minimize impact. In this study, introduce a new analysis method styled the Heat source of equivalent of the cable stayed bridge were conducted to verify the feasibility of numerical value analysis by comparing the results with the data measured. The thermal effects of Guss asphalt on the steel deck bridge according to temperature changes were also studied.

• 한국강구조학회 논문집
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• 제25권4호
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• pp.335-346
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• 2013

AASHTO LRFD 및 도로교한계상태설계기준에서는 신뢰도 기반 활하중 모델로부터 결정된 트럭하중과 차로하중을 동시에 재하하도록 하고 있으며, 트럭하중은 충격계수를 고려하되 차로하중은 충격계수를 적용하지 않도록 규정하고 있다. 본 연구에서는 중앙경간 230m, 400m 및 540m의 멀티케이블 강합성 사장교를 대상으로 트럭하중과 차로하중이 동시에 주행하는 경우에 대해 차량-교량 상호작용 해석을 수행하고 케이블과 보강거더의 충격계수를 평가하였다. 트럭하중은 6-자유도의 차량 모델을 사용하였으며, 차로하중은 일련의 1축 차량이 연행해서 주행하는 것으로 모사하였다. 교량의 감쇠비가 충격계수에 미치는 영향을 평가하였으며, 충격에 영향을 미치는 주요 인자인 노면조도와 주행속도를 해석변수로 고려하였다. 노면조도는 ISO 8608 규정에 근거하여 랜덤 생성하였으며, 차량-교량 상호작용해석 시 노면조도는 트럭하중에만 적용하였다. 한편, 사장교의 충격계수 평가를 위해 실무에서 사용되고 있는 영향선 기법에 의한 충격계수를 동적 상호작용 해석에 의한 결과와 비교하였다.

• 농촌계획
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• 제22권3호
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• pp.63-70
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• 2016

Due to the Korea's topographic characteristic, there are a lot of marine bridges to connect between islands and mainland. In addition, marine bridges play an important role in a regional landscape. For these reasons, landscape design of bridge is necessary in order to improve beautification of region. So, this studies analyzed image and landscape preference of marine bridges in rural area. The main results were summarized as follows: When rating the image of the background in sea and mountain image, 'stable' and 'natural' were rated highly. When rating the image of the arch bridge in sea and mountain image, 'beautiful', and 'attractive' were rated highly. When rating the image of the cable-stayed bridge in sea and mountain image, 'splendid', and 'attractive' were rated highly. When rating the image of the suspension bridge in sea and mountain image, 'beautiful', and 'splendid' were rated highly. Next, When rating the image of the background in sea and building image, 'stable' and 'natural' were rated highly. When rating the image of the arch bridge in sea and building image, 'beautiful', and 'splendid' were rated highly. When rating the image of the cable-stayed bridge in sea and building image, 'beautiful', and 'attractive' were rated highly. When rating the image of the suspension bridge in sea and building image, 'beautiful', and 'attractive' were rated highly. And, The image of suspension bridges in sea and mountain image is more highly preferred than other image. The background in sea and mountain image is landscape of the lowest preference. In the mountain and sea image, the preference of suspension bridge landscape has the highest rating. In the sea and building image, the preference of arch bridge landscape has the highest rating. In conclusion, the results illustrate that the marine bridge's shape and its background in rural area are important elements of a visual preference. When designing the marine bridge, designer have to choose a proper bridge shape for its background. However, this research's limitation is that this research consider only bridge shape and background to analyze landscape preference of marine bridges. Therefore, further research is necessary to consider various elements.

• 한국구조물진단유지관리공학회 논문집
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• 제18권3호
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• pp.93-100
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• 2014

본 연구는 교량의 상시계측자료인 고유진동수 및 고유모드를 기준으로 계측기반모델을 구성하고, 구조해석을 수행하여 교량 공용상태에서 사장케이블 장력평가를 수행하였다. 케이블 설치 위치에 따라 하중유형별 케이블 장력이 다르다는 것을 알 수 있다. 고정하중과 활하중에 의한 케이블 계측장력은 케이블 설치위치에 따라 차이가 크지 않으나 설계하중을 적용한 해석결과보다 큰 값을 나타낸다. 계측기반모델에 대한 케이블장력분포는, 설계모델에 대한 장력보다 크지만, 계측장력과 유사한 분포를 나타낸다. 그러므로 장기거동을 고려하여 사장교 케이블설계는 계측기반모델의 해석결과를 반영할 필요가 있다. 이를 위하여 많은 계측자료를 이용한 장기거동 분석연구가 요구된다.