• Structural Engineering and Mechanics
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• 제69권3호
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• pp.347-359
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• 2019

This paper aims to evaluate the behavior of Dorim-Goh bridge in Seoul, Korea, under static and dynamic loads effects by ambient trucks. The prestressed concrete (PSC) girders and reinforcement concrete (RC) slab of the bridge are evaluated and assessed. A short period monitoring system is designed which comprises displacement, strain and accelerometer sensors to measure the bridge performance under static and dynamic trucks loads. The statistical analysis is used to assess the static behavior of the bridge and the wavelet analysis and probabilistic using Weibull distribution are used to evaluate the frequency and reliability of the dynamic behavior of the bridge. The results show that the bridge is safe under static and dynamic loading cases. In the static evaluation, the measured neutral axis position of the girders is deviated within 5% from its theoretical position. The dynamic amplification factor of the bridge girder and slab are lower than the design value of that factor. The Weibull shape parameters are decreased, it which means that the bridge performance decreases under dynamic loads effect. The bridge girder and slab's frequencies are higher than the design values and constant under different truck speeds.

• 한국구조물진단유지관리공학회 논문집
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• 제13권1호통권53호
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• pp.205-213
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• 2009

본 연구에서는 사장교의 케이블 장력을 장기적인 관점에서 보다 효과적으로 분석하고 모니터링할 수 있는 케이블 장력 모니터링 시스템을 개발하는 연구를 수행하였다. 제안된 모니터링 시스템에는 실시간 동적 데이터에서 일정 대상시간 동안의 가속도 데이터를 선정하고, 이를 고속 푸리에 변환 알고리즘에 적용하여 주파수 분석한 결과를 평균하여 일반화시키는 신호해석이론이 적용되었다. 제안된 케이블 장력의 모니터링 시스템의 적용성을 평가하기 위하여 실제 공용중인 사장교에 대한 현장재하시험을 실시하였다. 현장계측을 통한 수동으로 계산된 장력과 모니터링 시스템의 강제저장 기능을 통해 저장된 데이터를 수계산하여 반자동으로 계산된 장력을 비교한 결과, 장력차이가 1% 이내로 발생하였고, 제안된 모니터링 시스템에서 자동으로 계산된 장력을 비교한 결과에서는 약 5% 범위의 무시할만한 차이로 나타나 본 연구에서 제안된 사장교 케이블 장력 모니터링 시스템의 신뢰도를 검증하였다.

• Smart Structures and Systems
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• 제6권3호
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• pp.277-290
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• 2010

Internationally the load carrying capacity of bridges is decreasing due to material deterioration while at the same time increasing live loads mean that they are often exposed to stresses for which they were not designed. However there are limited resources available to ensure that these bridges are fit for purpose, meaning that new approaches to bridge maintenance are required that optimize both their service lives as well as maintenance costs. Wireless sensor networks (WSNs) provide a tool that could support such an optimized maintenance program. In many situations WSNs have advantages over conventional wired monitoring systems in terms of installation time and cost. In order to evaluate the potential of these systems two WSNs were installed starting in July 2007 on the Humber Bridge and on a nearby approach bridge. As part of a corrosion prevention strategy, a relative humidity and temperature monitoring system was installed in the north anchorage chambers of the main suspension bridge where the main cables of the bridge are anchored into the foundation. This system allows the Bridgemaster to check whether the maximum relative humidity threshold, above which corrosion of the steel wires might occur, is not crossed. A second WSN which monitors aspects of deterioration on a reinforced concrete bridge located on the approach to the main suspension bridge was also installed. Though both systems have provided useful data to the owners, there are still challenges that must be overcome in terms of monitoring corrosion of steel, measuring live loading and data management before WSNs can become an effective tool for bridge managers.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.336-340
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• 2006

The cases of using new methods of big blocks are largely increasing on Recent large-scale bridge structures. So the accurate data of responses of bridges following environmental causes are required to be quickly recorded in order to predict. For this reason described above, the research on measuring system should be conducted for more knowledge of the details on application and stability of new methods. In this study, the new health monitoring system that can monitor the real behavior and damages of the bridge during all processes of construction is presented by analyzing cases of domestic and overseas bridge health monitoring system, and applied methods of following bridges.

• 비파괴검사학회지
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• 제27권6호
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• pp.556-562
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• 2007

This paper presents the use of a novel fiber optic accelerometer system to monitor ambient vibration (both wind-induced one and vehicle-induced) of a real bridge structure. This sensor system integrates the $Moir\'{e}$ fringe phenomenon with fiber optics to achieve accurate and reliable measurements. A low-cost signal processing unit implements unique algorithms to further enhance the resolution and increase the dynamic bandwidth of the sensors. The fiber optic accelerometer has two major benefits in using this fiber optic accelerometer system for monitoring civil engineering structures. One is its immunity to electromagnetic (EM) interference making it suitable for difficult applications in such environments involving strong EM fields, electrical spark-induced explosion risks, and cabling problems, prohibiting the use of conventional electromagnetic accelerometers. The other is its ability to measure both low- and high-amplitude vibrations with a constantly high resolution without pre-setting a gain level, as usually required in a conventional accelerometer. The second benefit makes the sensor system particularly useful for real-time measurement of both ambient vibration (that is often used for structural health monitoring) and strong motion such as earthquake. Especially, the semi-strong motion and the small ambient one are successfully simulated and measured by using the new fiber optic accelerometer in the experiment of the structural health monitoring of a real bridge.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.439-459
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• 2010

Structural health monitoring (SHM) of civil infrastructure using wireless smart sensor networks (WSSNs) has received significant public attention in recent years. The benefits of WSSNs are that they are low-cost, easy to install, and provide effective data management via on-board computation. This paper reports on the deployment and evaluation of a state-of-the-art WSSN on the new Jindo Bridge, a cable-stayed bridge in South Korea with a 344-m main span and two 70-m side spans. The central components of the WSSN deployment are the Imote2 smart sensor platforms, a custom-designed multimetric sensor boards, base stations, and software provided by the Illinois Structural Health Monitoring Project (ISHMP) Services Toolsuite. In total, 70 sensor nodes and two base stations have been deployed to monitor the bridge using an autonomous SHM application with excessive wind and vibration triggering the system to initiate monitoring. Additionally, the performance of the system is evaluated in terms of hardware durability, software stability, power consumption and energy harvesting capabilities. The Jindo Bridge SHM system constitutes the largest deployment of wireless smart sensors for civil infrastructure monitoring to date. This deployment demonstrates the strong potential of WSSNs for monitoring of large scale civil infrastructure.

• Smart Structures and Systems
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• 제26권5호
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• pp.667-680
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• 2020

This study aims at reporting a systematic procedure for evaluating the static and dynamic structural performance of steel bridges based on a short-period structural health monitoring measurement. Sungsu bridge located in Korea is considered as a case study presenting the most recent tests carried out to examine the bridge condition. Short-period measurements of Structural Health Monitoring (SHM) system were used during the bridge testing phase. A novel symmetry index is introduced using statistical analyses of deflection and strain measurements. Frequency Domain Decomposition (FDD) is implemented to the strain measurements to estimate the bridge mode shapes and damping ratios. Furthermore, Markov Chain Monte Carlo (MCMC) is also implemented to examine the reliability of bridge performance while ambient design trucks are in static or moving at different speeds. Strain, displacement and acceleration were measured at selected locations on the bridge. The results show that the symmetry index can be an efficient and useful measure in assessing the steel bridge performance. The results from the used method reveal that the performance of the Sungsu bridge is safe under operational conditions.

• 한국측량학회지
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• 제28권3호
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• pp.377-383
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• 2010

본 연구의 목적은 GPS를 이용하여 장대교량의 거동을 실시간으로 모니터링 할 수 있는 시스템을 구축하는데 있다. GPS 센서를 이용하여 장대교량의 실시간 변위를 계측함으로써 장대교량의 3차원적인 거동이 분석 되어지고 관리될 수 있다. 본 연구에서 개발한 장대교량의 실시간 거동 모니터링 시스템은 통합운영센터로 교량의 수평 및 수직 방향 변위와 위험신호를 실시간으로 전송함으로써 장대교량의 안전관리를 가능하게 한다. 또한 GPS를 이용한 장대교량의 절대적 거동을 모니터링하고 전국적인 교량 안전관리네트워크를 구축하는데 활용할 수 있을 것이다.

• 한국통신학회논문지
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• 제35권5B호
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• pp.824-832
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• 2010

구조물의 관리에서 전문 관리 인력이 직접 조사하는 방식은 예산이나 검사 방법 및 주기에 따라 그 효과가 달라진다. 따라서 효과적이며 자동화된 구조물의 유지관리 방안이 필요하다. 교량 관리에서 자동화된 관리 방안으로는 몇몇 교량에 유선통신 방식을 이용한 상시 감시 시스템을 구축, 운영하고 있으나 교량 통합관리 시스템으로서의 성능은 초보적인 수준에 머물고 있다. 본 논문에서는 센서 네트워크를 적용한 교량의 통합관제 시스템을 구현한다. 교량에 설치된 센서를 무선망으로 구성하고 수집된 정보의 상시 모니터링을 위해 교량 관리자를 위한 기능과 관리시스템 관리용 기능, 그리고 비전문가용 웹 기반 모니터링 시스템을 구축하였다. 본 연구의 결과는 실험대상 교량에 적용하여 그 효과를 분석하고 있다.

• Smart Structures and Systems
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• 제5권4호
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• pp.381-395
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• 2009

The paper presents a case study in which the structural condition assessment of the East Bay bridge in Gibsonton, Florida is evaluated with the help of remote health monitoring techniques. The bridge is a four-span, continuous, deck-type reinforced concrete structure supported on prestressed pile bents, and is instrumented with smart Fiber Optic Sensors. The sensors used for remote health monitoring are the newly emerged Fabry-Perot (FP), and are both surface-mounted and embedded in the deck. The sensing system can be accessed remotely through fast Digital Subscriber Lines (DSL), which permits the evaluation of the bridge behavior under live traffic loads. The bridge was open to traffic since March 2005, and the collected structural data have been continuously analyzed since. The data revealed an increase in strain readings, which suggests a progression in damage. Recent visual observations also indicated the presence of longitudinal cracks along the bridge length. After the formation of these cracks, the sensors readings were analyzed and used to extrapolate the values of the maximum stresses at the crack location. The data obtained were also compared to initial design values of the bridge under factored gravity and live loads. The study showed that the proposed structural health monitoring technique proved to provide an efficient mean for condition assessment of bridge structures providing it is implemented and analyzed with care.