• Title, Summary, Keyword: cable-stayed bridge

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Evaluation of Cable Tension Forces Using Vibration Method for a Cable-stayed Bridge under Construction (진동법을 이용한 사장교의 시공 중 장력 평가)

  • Cho, Soojin;Yun, Chung-Bang;Sim, Sung-Han
    • Journal of the Korean Society of Safety
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    • v.29 no.2
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    • pp.38-44
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    • 2014
  • When a cable-stayed bridge is under construction, the cable tension that changes according to the construction phase is the index indicating the proper construction management. In this study, the vibration method using the least-square estimation has been implemented to monitor changing tensions of two multi-strand cables of a cable-stayed bridge under construction. The test bridge is Hwamyung Bridge in Korea with a prestressed concrete box girder. The field tests are executed during the second tensioning stage just after the installation of the key segment. The tensions of two cables are measured before and after the tensioning and 5 days later (i.e., after finishing the tensioning of all cables). The accuracy of the estimated tensions by the vibration method has been improved by employing proper effective lengths of the cables. The measured tensions are compared with the result of the lift-off tests and design tensions. The vibration method shows very good performance in monitoring the changing tensions according to the construction phase with minimal error.

Investigation of modal identification and modal identifiability of a cable-stayed bridge with Bayesian framework

  • Kuok, Sin-Chi;Yuen, Ka-Veng
    • Smart Structures and Systems
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    • v.17 no.3
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    • pp.445-470
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    • 2016
  • In this study, the Bayesian probabilistic framework is investigated for modal identification and modal identifiability based on the field measurements provided in the structural health monitoring benchmark problem of an instrumented cable-stayed bridge named Ting Kau Bridge (TKB). The comprehensive structural health monitoring system on the cable-stayed TKB has been operated for more than ten years and it is recognized as one of the best test-beds with readily available field measurements. The benchmark problem of the cable-stayed bridge is established to stimulate investigations on modal identifiability and the present paper addresses this benchmark problem from the Bayesian prospective. In contrast to deterministic approaches, an appealing feature of the Bayesian approach is that not only the optimal values of the modal parameters can be obtained but also the associated estimation uncertainty can be quantified in the form of probability distribution. The uncertainty quantification provides necessary information to evaluate the reliability of parametric identification results as well as modal identifiability. Herein, the Bayesian spectral density approach is conducted for output-only modal identification and the Bayesian model class selection approach is used to evaluate the significance of different modes in modal identification. Detailed analysis on the modal identification and modal identifiability based on the measurements of the bridge will be presented. Moreover, the advantages and potentials of Bayesian probabilistic framework on structural health monitoring will be discussed.

Passive control system for seismic protection of a multi-tower cable-stayed bridge

  • Geng, Fangfang;Ding, Youliang;Song, Jianyong;Li, Wanheng;Li, Aiqun
    • Earthquakes and Structures
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    • v.6 no.5
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    • pp.495-514
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    • 2014
  • The performance of passive control system for the seismic protection of a multi-tower cable-stayed bridge with the application of partially longitudinal constraint system is investigated. The seismic responses of the Jiashao Bridge, a six-tower cable-stayed bridge using the partially longitudinal constraint system are studied under real earthquake ground motions. The effects of the passive control devices including the viscous fluid dampers and elastic cables on the seismic responses of the bridge are examined by taking different values of parameters of the devices. Further, the optimization design principle of passive control system using viscous fluid dampers is presented to determine the optimized parameters of the viscous fluid dampers. The results of the investigations show that the control objective of the multi-tower cable-stayed bridge with the partially longitudinal constraint system is to reduce the base shears and moments of bridge towers longitudinally restricted with the bridge deck. The viscous fluid dampers are found to be more effective than elastic cables in controlling the seismic responses. The optimized parameters for the viscous fluid dampers are determined following the principle that the peak displacement at the end of bridge deck reaches to the maximum value, which can yield maximum reductions in the base shears and moments of bridge towers longitudinally restricted with the bridge deck, with slight increases in the base shears and moments of bridge towers longitudinally unrestricted with the bridge deck.

Analysis of local vibrations in the stay cables of an existing cable-stayed bridge under wind gusts

  • Wu, Qingxiong;Takahashi, Kazuo;Chen, Baochun
    • Structural Engineering and Mechanics
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    • v.30 no.5
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    • pp.513-534
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    • 2008
  • This paper examines local vibrations in the stay cables of a cable-stayed bridge subjected to wind gusts. The wind loads, including the self-excited load and the buffeting load, are converted into time-domain values using the rational function approximation and the multidimensional autoregressive process, respectively. The global motion of the girder, which is generated by the wind gusts, is analyzed using the modal analysis method. The local vibration of stay cables is calculated using a model in which an inclined cable is subjected to time-varying displacement at one support under global vibration. This model can consider both forced vibration and parametric vibration. The response characteristics of the local vibrations in the stay cables under wind gusts are described using an existing cable-stayed bridge. The results of the numerical analysis show a significant difference between the combined parametric and forced vibrations and the forced vibration.

Seismic Protection of Cable-stayed Bridges Using LRB and MR Damper (납-고무받침과 자기유변유체 감쇠기를 이용한 사장교의 내진제어)

  • 정형조;박규식;이인원
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.241-245
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    • 2003
  • This paper presents the LRB-based hybrid base isolation system employing additional semiactive control devices for seismic protection of cable-stayed bridges by examining the ASCE first generation benchmark problem for a cable-stayed bridge. In this study, ideal magnetorheological dampers (MRDs) are considered as additional semiactive control devices. Numerical simulation results show that the hybrid base isolation system is effective in reducing the structural responses of the benchmark cable-stayed bridge under the historical earthquakes considered. The simulation results also demonstrate that the hybrid base Isolation system employing semiactive MRDs is robust to the stiffness uncertainty of the structure. Therefore, the LRB-based hybrid base isolation system employing MRDs could be appropriate in real applications for full-scale civil infrastructures.

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Time-dependent effects on dynamic properties of cable-stayed bridges

  • Au, Francis T.K.;Si, X.T.
    • Structural Engineering and Mechanics
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    • v.41 no.1
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    • pp.139-155
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    • 2012
  • Structural health monitoring systems are often installed on bridges to provide assessments of the need for structural maintenance and repair. Damage or deterioration may be detected by observation of changes in bridge characteristics evaluated from measured structural responses. However, construction materials such as concrete and steel cables exhibit certain time-dependent behaviour, which also results in changes in structural characteristics. If these are not accounted for properly, false alarms may arise. This paper proposes a systematic and efficient method to study the time-dependent effects on the dynamic properties of cable-stayed bridges. After establishing the finite element model of a cable-stayed bridge taking into account geometric nonlinearities and time-dependent behaviour, long-term time-dependent analysis is carried out by time integration. Then the dynamic properties of the bridge after a certain period can be obtained. The effects of time-dependent behaviour of construction materials on the dynamic properties of typical cable-stayed bridges are investigated in detail.

Design Specifications of Cable Stayed Bridge Across Chambal River (참발강 횡단 사장교의 설계기준)

  • Kim, Mo-Seh;Yoo, Jun-Yeol;Cho, Eu-Kyeong;Lee, Sang-Min
    • Magazine of the Korea Concrete Institute
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    • v.20 no.6
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    • pp.41-46
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    • 2008
  • The bridge across Chambal River consists of two approach bridges and a cable stayed bridge with concrete girder and pylon. And the main bridge has been designed mainly based on AASHTO LRFD. This article covers design specifications from AASHTO LRFD, which are applied to load combinations and structural verification. And it also covers local standards applied in definition of loads such as live load, wind load, temperature, etc. In addition, the difference between applied design specifications and Korean standards is mentioned in this article briefly.

Behavior of cable-stayed bridges built over faults

  • Raftoyiannis, I.G.;Michaltsos, G.T.;Konstantakopoulos, T.G.
    • Interaction and multiscale mechanics
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    • v.5 no.3
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    • pp.187-210
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    • 2012
  • Cable-stayed bridges are commonly used in modern bridge engineering for covering long spans. In some special cases, the designer is obliged to build such a bridge over an existing fault. Activation of this fault is possible to bring about a relative displacement or separation movement between two neighboring pylons of the bridge built on opposite sides of the fault. In this work, the effect of such a fault-induced pylon displacement on bridge's deformations and on cables' strength is thoroughly studied for several types of cable-stayed bridges and useful conclusions are drawn aiming the design. The influence of a possible earthquake and traffic loads crossing the bridge when the pylons are moving away from each other is not examined.

Entropy-based optimal sensor networks for structural health monitoring of a cable-stayed bridge

  • Azarbayejani, M.;El-Osery, A.I.;Taha, M.M. Reda
    • Smart Structures and Systems
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    • v.5 no.4
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    • pp.369-379
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    • 2009
  • The sudden collapse of Interstate 35 Bridge in Minneapolis gave a wake-up call to US municipalities to re-evaluate aging bridges. In this situation, structural health monitoring (SHM) technology can provide the essential help needed for monitoring and maintaining the nation's infrastructure. Monitoring long span bridges such as cable-stayed bridges effectively requires the use of a large number of sensors. In this article, we introduce a probabilistic approach to identify optimal locations of sensors to enhance damage detection. Probability distribution functions are established using an artificial neural network trained using a priori knowledge of damage locations. The optimal number of sensors is identified using multi-objective optimization that simultaneously considers information entropy and sensor cost-objective functions. Luling Bridge, a cable-stayed bridge over the Mississippi River, is selected as a case study to demonstrate the efficiency of the proposed approach.

Experimental Study on Dynamic Characteristics of Cable-Stayed Bridge (사장교의 동특성분석에 관한 실험적 연구)

  • 황학주;김상효;전귀현;박기태;신주환
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.209-216
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    • 1994
  • Recently, cable-supported long-span bridge are widely constructed due to improved quality of cable and development of design and construction techniques. In this study, an existing cable-stayed bridge, Dolsan Bridge, has been evaluated based on the cable forces measured using vibration method. And the finite element model using in this study for the dynamic analysis has been found to be quite comparable with dynamic mode shapes and natural frequencies estimated from experimental data induced by ambient traffic excitations.

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