• Journal of the Society of Disaster Information
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• v.13 no.2
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• pp.249-257
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• 2017

Recently, a cable disconnection accident occurred due to a lightning strike at the Seohae Bridge located in Dangjin-Pyeongtaek City. This is a natural occurrence, but it is a recall that it is very important to review the safety issues due to the disconnection of cable bridges. In other words, the role of cables in cable bridges has a profound effect on the safety of the structure, and it has become necessary to grasp the effect on the entire structural system. The cable bridge is an economic bridge that builds the main tower and supports the bottom plate by cable. The influence of the cable is the main member, which is a big influence on the safety of the whole bridge system. In the cable-stayed bridge, the cables exhibit nonlinear behavior because of the change in sag, due to the dead weight of the cable, which occurs with changing tension in the cable resulting from the movement of the end points of the cable as the bridge is loaded. Modal analysis is conducted using the deformed dead-load tangent stiffness matrix. A new concept was presented by using divided a cable into several elements in order to study the effect of the cable vibration (both in-plane and swinging) on the overall bridge dynamics. The result of this study demonstrates the importance of cable vibration on the overall bridge dynamics.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.5
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• pp.313-322
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• 2019

Recently, there have been frequent occurrences of bridge fires. Fires in cable-supported bridges can damage and brake cables due to high temperatures. In this study, fire scenarios that can occur on cable-supported bridges were set up. In addition, based on the results of vehicle fire tests, a fire intensity model was proposed and cable heat transfer analyses were performed on a target bridge. The analyses results demonstrated that temperature rises were identified on cables with a smaller cross-sectional area. Furthermore, vehicles other than tankers did not exceed the fire resistance criteria. When the tanker fire occurred on a bridge shoulder, the minimum diameter cable exceeded the fire resistance criteria; the height of the cable exceeding the fire resistance criteria was approximately 14 m from the surface. Therefore, the necessity of countermeasures and reinforcements of fire resistance was established. The results of this study confirmed that indirect evaluation of the temperature changes of bridge cables under fire is possible, and it was deemed necessary to further study the heat transfer analysis considering wind effects and the serviceability of the bridge when the cable temperature rises due to fire.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.5
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• pp.1-12
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• 2018

This study presents the seismic response characteristics of domestic cable-supported bridges due to 3 earthquakes with magnitudes of 5.1, 5.8, and 4.5 in Richter scale, which occurred around Gyeongju region in 2016. The seismic acceleration response signals, recorded by the seismic acceleration sensors at the free field near bridge and designated positions on bridge, are utilized to characterize the seismic responses of structural elements of cable-supported bridges. The dynamic behaviors of bridges are presented through Fourier transform of acceleration time history. Using the peak accelerations normalized by those at the free fields, amplification effects on the tops of the pylons are analyzed comparatively bridge by bridge. Using aforementioned analyses, the necessity of development on the creteria of alert levels is discussed for the earthquake disaster response of cable-supported bridges.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.6
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• pp.643-651
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• 2014

In this paper the reliability analyses of the cable-supported bridge design code which is recently issued in Korea are performed and the results are presented. Governing load combinations for the member design and the statistical properties of the main members are introduced and the analysis is performed using an example cable-stayed bridge for which the design is performed following the load and resistance factors defined in the design code. The reliability analysis shows the target reliability index can be achieved by applying load and resistance factors and the application of the resistance modification factor can enhance the reliability level if the importance of the bridge needs to be increased. The sensitivity analysis reveals that decreasing uncertainty of the cable strength is critical for obtaining the target reliability index. The study results show that the design using the load and resistance factors of the code can achieve the target reliability indexes for the design of cable supported bridge.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.48-51
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• 2011

사장교에서 케이블은 하중을 지지하는 주요 부재로, 케이블 장력은 사장교의 건전성과 안전도 평가에 있어서 매우 중요한 변수이다. 케이블 장력을 추정하기 위한 대표적인 방법으로는 로드셀을 이용한 직접법과 진동 계측 자료를 이용한 간접법 등이 있으며, 최근에는 자기장-응력 관계를 이용한 EM(Elasto-Magnetic) 센서 측정법이 개발되어 케이블 장력 추정에 적용되었다. 본 논문에서는 세 가지 장력 추정 기법을 실제 시공중인 사장교에 적용하여, 그 성능을 상호 비교하였다. 본 연구는 한국의 KAIST와 미국 Northeastern 대학교의 공동연구로 수행되었다. 대상 교량은 부산 화명동과 김해 초정리를 연결하기 위해 현재 건설중인 화명대교이다. 화명대교의 교량 형식은 2주탑 콘크리트 사장교 (주탑 경간장 270m, 총 사장교 구간장 500m)이며, 사장재로는 MS (Multi-Strand) 형 케이블이 사용되었다. 실험 당시 화명대교는 중앙경간의 폐합 후 선형관리를 위한 장력조정작업을 수행하였으며, 케이블 재긴장시의 정확한 장력관리를 위하여 로드셀을 이용한 Lift-off test방법으로 케이블의 장력을 측정하였다. 이와 동시에 두 개의 케이블을 대상으로 진동 가속도 센서와 EM 센서를 설치하고 장력 계측을 수행하였으며, 재긴장 단계별 장력 변화치를 지속적으로 계측하였다. 계측된 결과를 바탕으로 케이블 장력 추정 기법의 정확성 및 실교량에서의 활용성을 비교하였다.

• The Journal of the Convergence on Culture Technology
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• v.9 no.4
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• pp.633-638
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• 2023

In this study, the effect of the change in cable tension on the track irregularity of railway ballasted track on a railway steel composite bridge was analyzed. As a result of comparing design and analysis results for cable tension, a difference of less than 3% was found, and analysis modeling was analyzed to reflect the design conditions well. In addition, the adequacy of the analysis modeling was demonstrated by comparing the field measurement results with the analysed cable tension. By considering the change in cable tension as a variable, the track irregularity of the railway steel composite bridge was analyzed. As a result of the analysis, it was analyzed that the total and one-sided cable tension change had a direct effect on the vertical irregularity among the track irregularity items. In addition, it was found that the change in track irregularity occurred in the section close to the cable position. It was analyzed that the change in cable tension had a more direct effect on track irregularity that had a direct correlation with the vertical direction rather than the lateral direction.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.214-217
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• 2011

두가현수교는 2010년 8월 집중호우로 인해 유실된 교량을 복구하기 위한 과업으로서 향후 재발방지를 위해 중앙 경간장을 증가시켜 통수단면적을 추가확보하고, 교량 여유고를 상향시켜 수해에 대비한 견고한 교량으로 계획하였다. 또한 보행자의 통행을 위한 보도육교의 특성을 고려하여 지역의 관광자원이 될 수 있도록 중앙경간 125m의 V형 주탑 3차원 보도현수교로 설계하였다. 보강거더는 H-Beam을 이용하여 자재 수급 및 취급이 용이하며 강재 바닥판을 적용하여 보다 경량화된 보강거더를 적용함으로써 주케이블의 장력 감소에도 기여하도록 하였으며, 행어정착을 위한 별도의 정착거더를 채택한 ${\pi}$형식을 채택하여 풍동실험을 통해 내풍 안정성을 확인하였다. 주케이블 및 행어는 미관, 구조적 안정성, 유지관리성 및 가설의 용이함을 고려하여 PE를 피복한 PWS케이블을 선정하였다. 경관을 고려한 V형 주탑을 이용한 3차원 케이블을 채택하여 지역의 상징물을 표현하였으며 기초의 규모를 최소화 하였다. 또한 H형 및 A형 주탑과의 비교를 통해 V형 주탑 교량의 특성을 검토하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.2
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• pp.113-120
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• 2008

This study presents the ULMM(unstrained-length-modification method) to determine the cable tension consistent with target tension after arrangement of cable-members by controlling the unstrained length of cables. This method used to be shown to determine the exact unstrained length for cable-supported bridge with elastic catenary cable. The some verification examples show to determine the unstrained length that satisfies the target tension and to obtain the satisfactory result for cable-supported bridge. Accordingly this modification method of the unstrained length in this study is used to introduce the satisfactory target tension.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.105-111
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• 2018

This study aims to evaluate the safety for cable stayed bridge due to damages on the cable system. Many cable supported bridges, including cable stayed bridge and suspension bridge, have been built in the Korean peninsula. This requires efficient maintenance and management since this structure has complex structural components and system. This large structure also often faces risks either from manmade or natural phenomenon. In 2015 one cable-stayed bridge in South Korea had been struck by a bolt of lightning on the cables. This event had led to fire on cables. These cables had been damaged and putting the bridge at risk. This bridge was back in used after a few weeks of investigations and replacements of the cables. However, enormous social and economic expense were paid for recovery. After this event risk based management for infra structures is required by public demands. Therefore, this study was initiated and aimed to evaluate risks on the cable system due to potential damages. In this paper one cable-stayed bridge in South Korea was selected and investigated its safety based on the damage scenarios of cable system for efficient and prompt management, and for supporting decision making. FEM analysis was conducted to evaluate the safety of the bridges due to damages on the cable system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.74-79
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• 2020

Safety inspection of cable-supported bridge has increasingly attention as many cable-supported bridges are currently constructed/operated. Whilst cables as a main component in cable-supported bridge should be inspected regularly, traditional method (visual inspection) has limitation to check the condition of cables properly due to restricted factors. It is evidently necessary to develop cable-inspection robot to overcome this concern. In this respect, the main aim in this study is to manufacture the improved robot compared with the existing robot. The improved functions of the robot in this study were that the robot can be operated in large cable diameter (greater than 200 mm) and climbing ability of the robot increases. In addition, electro-magnetic sensor as a non-destructive method in the robot was added to detect damaged cables and performance of the sensor was evaluated in indoor and field experiments. Consequently, the robot was able to move on the cable with ~0.2m/s and to detect damaged cables using the sensor. It was also confirmed that performance of the robot in field test is similar to that in indoor test.