• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.641-646
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• 2002

A new damage detection technique using static displacement data was developed, in order to assess the structural integrity of bridge structures. In conventional damage assessment techniques using dynamic response, the variation of natural frequencies is intrinsically insensitive to the damage of the bridge: thus, it is usually difficult to obtain them from the measured data. The proposed detection method enables the estimation of the stiffness reduction of bridges using the static displacement data that are measured periodically, without requiring a specific loading test. Devices such as a laser displacement sensor can be used to measure static displacement data due to the dead load of the bridge structure. In this study, structural damage was represented by the reduction in the elastic modulus of the element. The damage factor of the element was introduced to estimate the stiffness reduction of the bridge under consideration. Likewise, the proposed algorithm was verified using various numerical simulations and compared with other damage detection methods. The effects of noise and number of damaged elements on damage detection were also investigated. Results showed that the proposed algorithm efficiently detects damage on the bridge.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.2 s.54
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• pp.145-152
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• 2009

In performing a risk analysis on structure for earthquake, it is imperative to identify the vulnerability of structures associated with various stages of damage. And the earthquake resisting capability is needed for structures like bridge. So the damage analysis of bridges with or without isolator for earthquake effects is necessary. In this paper, the risk analysis of seismic isolated LRB bridges considering earthquake effects such as PGA, PGV, SA, SV, and SI is performed using fragility curves to assure the earthquake resisting capability of the structures. And, the stability of fragility curve is investigated with respect to input earthquake.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.101-104
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• 2008

Recently, the serious damage by earthquakes is increased around the world. SOC fo city is established to minimize the loss of lives and assets by earthquakes, which an objective standard is required. Generally, bridges damage by earthquakes occurred the inelastic hinge under the column. Nonlinear element model of inelastic hinge have been used to Bilinear model, but Takeda model for material characterization of concrete is a little. In this study, railway bridge was performed seismic fragility analysis for Takeda model and Bilinear model comparatively. This analysis shows that damage probability of Takeda model is larger than Bilinear model. And analysis of Takeda model in longitudinal direction and transverse direction are different. Therefore developed analysis for concrete column of bridge is expected to apply to material characterization.

• The Journal of the Convergence on Culture Technology
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• v.5 no.1
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• pp.389-394
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• 2019

In case of damaged timber sleepers, maintenance is carried out according to the track inspection standard. However, it is difficult to detect the extent of damage on the bridge, and maintenance is depended on inspector's judgment. In this study, we propose to improve the evaluation criterion of timber sleepers for the ballast-less tracks on serviced urban railway bridge. The timber sleepers on railway bridge was classified according to degree of damage, and damage scores were calculated for each damage grade. Also we have improved the maintenance system of the timber sleepers through the history management system of the individual timber sleepers on railway bridge. As a results, it was judged that systematic management of timber sleepers could be possible during maintenance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.5
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• pp.543-553
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• 2023

This study was conducted to propose a simple method to evaluate the load-carrying capacity of RC slab bridges, which have been most frequently constructed in Korea. A number of RC slab bridges have been considerably deteriorated associate with the long service year. However, since these bridges are not included in the 1st and 2nd class infrastructures due to their short span length, they have been relatively neglected compared to other bridge types in terms of safety management. In the previous theoretical study, a process (draft) was proposed for evaluating the damage of RC slab bridges using the relationship between the displacement response ratio and the stiffness reduction rate derived by the measured displacement and natural frequency. In this paper, to verify the validity of the proposed damage evaluation process (draft), the results to the actual bridges were compared with the safety grade and the Matsui's deterioration index. In addition, to enhance the practical applicability of the existing process (draft), an improved method approximately evaluating the load-carrying capacity using only the measured natural frequency was presented. If an error of 10% of the load-carrying capacity is allowed, it is judged that the proposed damage evaluation process can be appropriately used not only for evaluating the safety of RC slab bridges, but also for determining priorities for their maintenance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.19-26
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• 2021

The seismic isolation system have been applied in order to protect the collapse of bridge by seismic load and the vertical load transmitted from the superstructure. However, the failure and damages of non-shrinkage mortar, isolator and wedge in total 12 bridge were reported by Pohang Earthquake. In this study, the damage mechanism and behavior characteristics of elastomeric bearing by an earthquake were evaluated to consider the seismic isolation system including non-shrinkage mortar and the seat concrete of pier. To discuss the effect of installed wedge and damage mode of elastomeric bearing, the compressive-shear tests were carried out. Also, the mechanical behaviors and damage mechanism for each component of elastomeric bearing were evaluated by using finite element analysis. From the test results, the cracks were created at boundary between non-shrinkage mortar and seismic isolator and the shear loads were rapidly increased after bump into wedge. The cause for damage mechanism of seismic isolation system was investigated by comparing stress distribution of anchor socket and non-shrinkage mortar depending on wedge during earthquake.

• Journal of Ocean Engineering and Technology
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• v.10 no.4
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• pp.17-27
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• 1996

본 연구는 진동반응측정을 통해 구조물의 손상을 비파괴적으로 예측하는 분야에 속한다. 건물, 교량, 댐, 해양자켓, 원자력 발전소 등의 구조물에서 시기적절하고 정확한 손상의 발견은 치명적인 구조적 결함의 예방을 위해 필수적이다. 구조물의 진동반응을 측정하여 구조물의 손상발견을 예측하려는 연구는 지난 80년대 이후 활발히 수행되어 오고 있으며, 본연구는 구조물 고유진동수의 변화로 부터 구조물 강성도의 변화를 모니터링하는 연구분야에 속한다. 본 연구의 목적은 현존하는 시스템동일화 (system identification)에 의한 손상발견법의 적합성을 검증하는 것이다. 먼저, 실물실험된 삼차원 트러스교량이 선택되었다. 다음으로, 시스템 동일화 개념에 기초한 손상발견법이 요약되었다. 마지막으로, 시스템 동일화 손상발견법을 실물트러스에 적용하여 적합성을 실험하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.4
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• pp.224-232
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• 1998

구조물에 손상이 발생하게 되면 동적특성이 변하게 된다. 그러므로 이와 같은 특성을 계측하여 구조물의 손상된 정도를 평가하게 되면 이를 상시감시에 활용할 수가 있다. 대표적인 손상기술들을 제작된 모형교량에 서로 다른 경계조건을 구현하여 손상도를 Simulation을 이용하여 결정하고 가장 적법한 방법과 대책을 연구했다. 모형교량은 I-DEAS의 Normal Mode Dynamic Solver를 이용하여 분석 제작되어 계측과 비교평가 되어 손상기술에 적용되었다. 24개의 가속도 감지기를 이용하여 데이터를 획득하였고, Residue법으로 모달인자를 추출하였다. 추출된 동적인자가 상시감시에 적용하도록 구조물의 손상검출기술을 제안한다

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.1
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• pp.103-111
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• 1999

구조물에 손상이 발생하게 되면 동적특성이 변하게 된다. 그러므로 이와 갈은 특성을 계측하여 구조물의 손상된 정도를 평가하게 되면 이를 상시감시에 활용할 수가 있다. 대표적인 손상기술들을 제작된 모형교량에 서로 다른 경계조건을 구현하여 손상도를 Simulation을 이용하여 결정하고 가장 적법한 방법과 대책을 연구했다. 모형교량은 I-DEAS의 Normal Mode Dynamic Solver를 이용하여 분석 제작되어 계측과 비교평가 되어 손상기술에 적용되었다. 24개의 가속도 감지기를 이용하여 데이터를 획득하였고, Residue법으로 모달인자를 추출하였다. 추출된 동적인자가 상시감시에 적용하도록 구조물의 손상검출기술을 제안한다

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.106-109
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• 2009

본 논문에서는 교량의 상태감시 테스트베드 구축을 위한 한-미 국제공동연구의 현황 및 활동 내용들을 논하였다. 이 국제공동연구는 최첨단 센서와 구조건전도 모니터링 방법의 유용성 및 통합화하는데 그 목적을 두고 있다. 테스트베드 구축을 위해 가속도계과 동적 FBG 센서, 압전 센서 등과 같은 스마트 센서를 사용하였으며, 무선 데이터수집 시스템이 도입되었다. 교량 모니터링 기법으로는 압전 센서 및 EM센서로부터 취합된 데이터를 이용하여 국부손상검색을 수행하였으며, 가속도계, 동적 FBG센서 및 이미지 프로세싱을 이용하여 진동기반 전역손상검색을 수행하였다. 테스트베드 교량으로는 PC박스 거더교, 강상자형교, 강판형교, 사장교의 4가지 형식의 교량이 사용되었다. 테스트베드 교량에 최신 이동통신 인터넷 연결기술을 이용하여 교량에 설치된 센서로부터 취합된 데이터와 모니터링 시스템으로부터 교량의 상태를 실시간 감시할 수 있는 네트워크 시스템을 구축하였다. 이러한 원거리 이동통신시스템을 통하여 구조물의 건전성 평가결과를 실시간으로 전송 및 분석할 수 있도록 하였다.