• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.291-301
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• 1998

In this paper, two dimensional and three dimentional modeling techniques are proposed for the failure analysis of deteriorated reinforced concrete T-girder bridge subjected to cyclic loading up to failure. For the nonlinear failure anaysis, a tension stiffening model which can consider degradation of bond between reinforcement and surrounding concrete due to corrision of rebars in old bridge is proposed and a modeling technique for the supports conditions of the bridges which can consider degradation of bearing at supports in old bridge is also proposed, The analysis results along with comparisons with full-scale failure-test results confirm that finite element modeling techniques in this paper can be well applied to the failure analyses of in-situ old reinforced concrete T-girder bridges subjected to cyclic loading and the support condition modeling especially affects the bridge strength significantly.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.4
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• pp.231-241
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• 2021

Although the deterioration of bridges may occur due to various causes, one of the representative causes is that the chloride used for deicing in the winter penetrates bridge members and results in corrosion. This study aims to quantify the ageing degree resulting from the corrosion of a bridge, apply it to the inelastic dynamic analysis model of the bridge, perform a seismic fragility analysis, and evaluate the relationship between the ageing degree and the seismic fragility curve. It is important to appropriately define the threshold values for each damage state in seismic fragility analyses considering the ageing degree. The damage state was defined using the results of existing experimental studies on the characteristics of the deterioration in the displacement ductility capacity of the pier, according to the ageing degree. Based on the seismic fragility analyses of six types of bridges divided by three types of bearing devices and two pier heights, it was found that the seismic vulnerability tends to increase with the ageing degree. The difference in seismic vulnerability with respect to the ageing degree exhibits a tendency to increase as the damage state progresses from slight to moderate, severe, and collapse.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.177-184
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• 2021

In recent years, large-scale earthquake activity has occurred in Korea, and thus public interest in earthquakes is increasing. Accordingly, the importance of seismic performance management of structures is emerging. In particular, the collapse of a bridge, one of main road facilities, directly leads to many casualties. Therefore, engineers need to evaluate the seismic fragility of the bridge and prepare for the earthquake event. The service life of these bridges has been over 30 years, which requires a study on the aging effect on bridges. In this study, seismic analysis of the target RC slab bridge was performed considering the aging effects of each component of the bridge. Components of the bridge included pier and bearing, which dominate the seismic response of the bridge. The seismic performance of the bridge was evaluated using nonlinear static and dynamic analyses. In addition, the limit state and dynamic response of each component were used to evaluate the seismic fragility according to the aging of each component.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.34-41
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• 2020

In recent years, magnitude and frequency of earthquakes have increased in Korea. Damage to a bridge, which is one of the main infrastructures, can directly lead to considerable loss of human lives. Therefore, engineers need to evaluate the seismic fragility of the structure and prepare for the possible seismic damage. In particular, the number of aging bridges over 30 years of service increases, and thus the seismic analysis and fragility requires accounting for the aging and retrofit effects on the bridge. In this study, the nonlinear static and dynamic analyses were performed to evaluate the effects of the aging and FRP retrofit on a PSC bridge. The aging and FRP retrofit were applied to piers that dominate the response of the bridge during earthquakes. The maximum displacement of the bridge increased due to the aging of the pier but decreased when FRP retrofit applied to the aged pier. In addition, seismic fragility analysis was performed to evaluate the seismic behavior of the bridge combined with the seismic performance of the pier. Compared with the aged bridge, the FRP retrofit bridge showed a decrease in the seismic fragility in all levels of damage. The reduction of the seismic fragility in the FRP bridge was prominent as the value of PGA and level of damage increased.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.12
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• pp.357-362
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• 2023

Bridges are important transportation infrastructure, but they are subject to damage and cracking due to various environmental factors and constant traffic loads, which accelerate their aging. With many bridges now older than their original construction, there is a need for systems to ensure safety and diagnose deterioration. Bridges are already utilizing structural health monitoring (SHM) technology to monitor the condition of bridges in real time or periodically. Along with this technology, the development of intelligent bridge monitoring technology utilizing artificial intelligence and Internet of Things technology is underway. In this paper, we study an edge system technique for predicting bridge safety using fast Fourier transform and dimensionality reduction algorithm for maintenance of aging bridges. In particular, unlike previous studies, we investigate whether it is possible to form a dataset using sensor data collected from actual bridges and check the safety of bridges.

• Korean Journal of Construction Engineering and Management
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• v.10 no.2
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• pp.102-110
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• 2009

The cost for maintenance of bridge structures such as repair or reinforcement is increasing. In addition, the efforts for inspection of bridge structures is becoming more important since the proper repair or reinforcement should be performed to save the maintenance cost and ensure the safety for public infrastructure. Therefore, it is studied on this paper to estimate the repair or reinforcement cycles using probabilistic approach for the steel-box girders of bridge superstructure. In addition, a computer simulation program is uniquely developed based on probabilistic approach to calculate the cycles derived from the function of age of bridge and performance rating curve which were previously studied. In order to ensure the reliability of results and appropriateness of the model, statistical analyses were performed. Also, the results were compared and proved to be similar with ones from previous statistical data related to the repair or reinforcement cycles. The results from this study is expected to be useful for the determination of proper time to repair or reinforce the bridge structure and raise the safetyness of bridge structure in advance.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.3
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• pp.149-158
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• 2022

As a bridge ages, its mechanical properties and structural performance deteriorate, degrading its seismic performance during a strong earthquake. In this study, the aging of piers and bridge bearings was quantified in several stages and reflected in the analysis model, enabling the evaluation of the member-level seismic fragility of these bearings. Moreover, by assuming that the failure mechanism of a bridge system is a series system, a method for evaluating the system-level seismic fragility based on the member-level seismic fragility analysis result is formulated and proposed. For piers with rubber and lead-rubber bearings (members vulnerable to aging effects), five quantitative degrees of aging (0, 5, 10, 25, and 40%) are assumed to evaluate the member-level seismic fragility. Then, based on the result, the system-level seismic fragility evaluation was implemented. The pier rather than the bridge bearing is observed to have a dominant effect on the system-level seismic fragility. This means that the seismic fragility of more vulnerable structural members has a dominant influence on the seismic fragility of the entire bridge system.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.27-31
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• 2011

차량의 대형화 및 고속화, 그리고 기존 교량의 노후화를 고려하였을 때, 교량의 건전성 평가는 매우 중요해지고 있다. 거동을 예측하는데 사용되는 유한요소 모델의 신뢰도는 이상적인 가정과 모델링 오차, 교량의 노후화 등에 의해 실제 거동을 반영하지 못하는 경우가 많다. 유한요소 모델의 신뢰도를 높이기 위해, 실제 교량의 거동을 계측하여, 이를 기반으로 물리적 의미를 가지는 변수들과 지점의 조건을 수정하는 모델의 개선이 주로 행해진다. 이러한 모델 개선은 최적화 기법을 통해 수행된다. 본 연구에서는 목적함수간 가중치에 의한 모델 개선 결과의 영향과 다중 목적 함수 최적화 기법을 통해, 가중치의 영향을 줄이고, 다양한 개선 모델들을 구하는데 적용하였다. 팔곡 3교의 실제 계측 데이터를 이용하여 단일 다중 목적 함수 기반의 모델 개선을 수행하였다. 단일 목적 함수의 경우, 정의되는 목적함수는 주로 고유진동수와 모드 형상에 관한 차이의 가중치 합으로 표현되어 지며, 이러한 가중치에 따라, 모델 개선의 결과에 영향을 가함을 확인하였다. 다중 목적 함수 기반의 모델 개선을 통해, 구해진 모델 개선 결과를 단일 목적 함수 기반 모델 개선의 결과들과 비교하였으며, 모델 개선에 대한 다중 목적 함수 최적화 적용을 분석하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.3
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• pp.251-262
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• 2003

LCP(Life Cycle Profiles) of bridge structures are indispensable for the LCC(Life Cycle Cost) evaluations of bridge system. The bridge under considerations may be newly-designed one or one in service. Thus, a systematic study of LCP is essential for both reliable LCC evaluation and strategic bridge management. LCP is mainly influenced by the structural environment in nature. However, in Korea, LCC evaluation has been performed with the LCP of foreign research results or only with the pieces of professional engineers' opinion. Therefore, to alleviate the drawbacks of foreign LCP and to enhance the reliability of current LCP, LCP should be established using the available data in bridge management system(BMS). In this study, LCP along with a subset of the BMS data was investigated and several mathematical expressions were proposed and evaluated. The condition ratings of a bridge were trasformed into the numerical indices through fuzzy logics with real field data. From the numerical results, it is concluded that the mathematical LCP model of $y=\sqrt{y^2_0-at}$ is shown to be the fittest one (R=0.815) to express the condition rating varied with the age. This has been drawn from the case study of slab bridges under the similar conditions.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2006.11a
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• pp.332-335
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• 2006

최근 건설되고 있는 교량 대부분은 장대교라 명명할 정도로 그 길이가 매우 길게 되어 교량의 노후화, 차량의 증가 및 대형화로 인한 교량의 피로 축적, 예기치 않은 자연재해 등에 의해 붕괴 위험에 노출되어 있다. 따라서 이러한 위험을 사전에 예측하기 위해서는 효율적인 교량모니터링 시스템의 설계가 필수적으로 요구된다. 본 연구에서는 최근 각광을 받고 있는 유비쿼터스 센서 네트워크 기술을 이용한 효율적인 교량 모니터링 시스템을 제안하고 이의 유용성을 확인해 보고자 한다.