• Title, Summary, Keyword: cable-stayed bridge

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Quasi-static Responses Estimation of a Cable-stayed Bridge from Displacement Data at a Limited Number of Points

  • Choi, Junho;Lee, Keesei;Kang, Youngjong
    • International journal of steel structures
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    • v.17 no.2
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    • pp.789-800
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    • 2017
  • Cable-stayed bridges are one kind of long-span bridges and are widely used. The girder of a cable-stayed bridge is slender and connected to the pylon with a cable. The girder of the cable-stayed bridge is subjected to a significant compressive force compared to other bridge types because of cable tension. The compression force can cause buckling failure of the girder. When a cable or girder fails, the equilibrium condition of the entire bridge is changed. For these reasons, it is important to monitor the structure condition to proactively detect bridge defects. In many cases, the acceleration or displacement of the structure is used to detect the defects. If as much displacement information as the degrees of freedom can be obtained, it is possible to estimate the condition of each of the members of the structure. However, as only a limited number of displacements can be acquired, SRALD 1.0 was proposed in order to overcome such limitations. In this research, SRALD 1.0 is used to analyze the responses of a cable-stayed bridge using a limited number of displacements. Limited numbers of displacement responses are used to estimate deformed shapes of the structure. In addition, the cable tension, axial force, and bending moment of the girder are estimated to analyze the characteristics of SRALD 1.0. Finally, the application of SRALD 1.0 was validated by comparing its algorithm with spline interpolation method, which is widely used to show the deformed shape of the structure.

Influence of lateral motion of cable stays on cable-stayed bridges

  • Wang, P.H.;Liu, M.Y.;Huang, Y.T.;Lin, L.C.
    • Structural Engineering and Mechanics
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    • v.34 no.6
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    • pp.719-738
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    • 2010
  • The aim of this paper concerns with the nonlinear analysis of cable-stayed bridges including the vibration effect of cable stays. Two models for the cable stay system are built up in the study. One is the OECS (one element cable system) model in which one single element per cable stay is used and the other is MECS (multi-elements cable system) model, where multi-elements per cable stay are used. A finite element computation procedure has been set up for the nonlinear analysis of such kind of structures. For shape finding of the cable-stayed bridge with MECS model, an efficient computation procedure is presented by using the two-loop iteration method (equilibrium iteration and shape iteration) with help of the catenary function method to discretize each single cable stay. After the convergent initial shape of the bridge is found, further analysis can then be performed. The structural behaviors of cable-stayed bridges influenced by the cable lateral motion will be examined here detailedly, such as the static deflection, the natural frequencies and modes, and the dynamic responses induced by seismic loading. The results show that the MECS model offers the real shape of cable stays in the initial shape, and all the natural frequencies and modes of the bridge including global modes and local modes. The global mode of the bridge consists of coupled girder, tower and cable stays motion and is a coupled mode, while the local mode exhibits only the motion of cable stays and is uncoupled with girder and tower. The OECS model can only offers global mode of tower and girder without any motion of cable stays, because each cable stay is represented by a single straight cable (or truss) element. In the nonlinear seismic analysis, only the MECS model can offer the lateral displacement response of cable stays and the axial force variation in cable stays. The responses of towers and girders of the bridge determined by both OECS- and MECS-models have no great difference.

Aerostatic load on the deck of cable-stayed bridge in erection stage under skew wind

  • Li, Shaopeng;Li, Mingshui;Zeng, Jiadong;Liao, Haili
    • Wind and Structures
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    • v.22 no.1
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    • pp.43-63
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    • 2016
  • In conventional buffeting theory, it is assumed that the aerostatic coefficients along a bridge deck follow the strip assumption. The validity of this assumption is suspect for a cable-stayed bridge in the construction stages, due to the effect of significant aerodynamic interference from the pylon. This situation may be aggravated in skew winds. Therefore, the most adverse buffeting usually occurs when the wind is not normal to bridge axis, which indicates the invalidity of the traditional "cosine rule". In order to refine the studies of static wind load on the deck of cable-stayed bridge under skew wind during its most adverse construction stage, a full bridge 'aero-stiff' model technique was used to identify the aerostatic loads on each deck segment, in smooth oncoming flow, with various yaw angles. The results show that the shelter effect of the pylon may not be ignored, and can amplify the aerostatic loading on the bridge deck under skew winds ($10^{\circ}-30^{\circ}$) with certain wind attack angles, and consequently results in the "cosine rule" becoming invalid for the buffeting estimation of cable-stayed bridge during erection for these wind directions.

Stability analysis of steel cable-stayed bridges

  • Tang, Chia-Chih;Shu, Hung-Shan;Wang, Yang-Cheng
    • Structural Engineering and Mechanics
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    • v.11 no.1
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    • pp.35-48
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    • 2001
  • The objective of this study is to investigate the stability behavior of steel cable-stayed bridges by comparing the buckling loads obtained by means of finite element methods with eigen-solver. In recent days, cable-stayed bridges dramatically attract engineers' attention due to their structural characteristics and aesthetics. They require a number of design parameters and present a high degree of static indetermination, especially for long span bridges. Cable-stayed bridges exhibit several nonlinear behaviors concurrently under normal design loads due to the individual nonlinearity of substructures such as the pylons, stay cables, and bridge deck, and their interactions. The geometric nonlinearities arise mainly from large displacements of cables. Strong axial and lateral forces acting on the bridge deck and pylons cause structural nonlinear behaviors. The interaction is among the substructures. In this paper, a typical three-span steel cable-stayed bridge with a variety of design parameters has been investigated. The numerical results indicate that the design parameters such as the ratio of $L_1/L$ and $I_p/I_b$ are important for the structural behavior, where $L_1$ is the main span length, L is the total span length of the bridge, $I_p$ is the moment of inertia of the pylon, and $I_b$ is the moment of inertia of the bridge deck. When the ratio $I_p/I_b$ increases, the critical load decreases due to the lack of interaction among substructures. Cable arrangements and the height of pylon are another important factors for this type of bridge in buckling analysis. According to numerical results, the bridges supported by a pylon with harp-type cable arrangement have higher critical loads than the bridges supported by a pylon with fan-type cable arrangement. On contrary, the shape of the pylon does not significantly affect the critical load of this type of bridge. All numerical results have been non-dimensionalized and presented in both tabular and graphical forms.

Earthquake response of isolated cable-stayed bridges under spatially varying ground motions

  • Ates, Sevket;Soyluk, Kurtulus;Dumanoglu, A. Aydin;Bayraktar, Alemdar
    • Structural Engineering and Mechanics
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    • v.31 no.6
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    • pp.639-662
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    • 2009
  • A comprehensive investigation of the stochastic response of an isolated cable-stayed bridge subjected to spatially varying earthquake ground motion is performed. In this study, the Jindo Bridge built in South Korea is chosen as a numerical example. The bridge deck is assumed to be continuous from one end to the other end. The vertical movement of the stiffening girder is restrained and freedom of rotational movement on the transverse axis is provided for all piers and abutments. The longitudinal restraint is provided at the mainland pier. The A-frame towers are fixed at the base. To implement the base isolation procedure, the double concave friction pendulum bearings are placed at each of the four support points of the deck. Thus, the deck of the cable-stayed bridge is isolated from the towers using the double concave friction pendulum bearings which are sliding devices that utilize two spherical concave surfaces. The spatially varying earthquake ground motion is characterized by the incoherence and wave-passage effects. Mean of maximum response values obtained from the spatially varying earthquake ground motion case are compared for the isolated and non-isolated bridge models. It is pointed out that the base isolation of the considered cable-stayed bridge model subjected to the spatially varying earthquake ground motion significantly underestimates the deck and the tower responses.

Buffeting response control of a long span cable-stayed bridge during construction using semi-active tuned liquid column dampers

  • Shum, K.M.;Xu, Y.L.;Guo, W.H.
    • Wind and Structures
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    • v.9 no.4
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    • pp.271-296
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    • 2006
  • The frequency of a traditional tuned liquid column damper (TLCD) depends solely on the length of liquid column, which imposes certain restrictions on its application to long span cable-stayed bridges during construction. The configuration of a cable-stayed bridge varies from different construction stages and so do its natural frequencies. It is thus difficult to apply TLCD with a fixed configuration to the bridge during construction or it is not economical to design a series of TLCD with different liquid lengths to suit for various construction stages. Semi-active tuned liquid column damper (SATLCD) with adaptive frequency tuning capacity is studied in this paper for buffeting response control of a long span cable-stayed bridge during construction. The frequency of SATLCD can be adjusted by active control of air pressures inside the air chamber at the two ends of the container. The performance of SATLCD for suppressing combined lateral and torsional vibration of a real long span cable-stayed bridge during construction stage is numerically investigated using a finite element-based approach. The finite element model of SATLCD is also developed and incorporated into the finite element model of the bridge for predicting buffeting response of the coupled SATLCD-bridge system in the time domain. The investigations show that with a fixed container configuration, the SATLCD with adaptive frequency tuning can effectively reduce buffeting response of the bridge during various construction stages.

Development of BIM-based bridge maintenance system for cable-stayed bridges

  • Shim, Chang-su;Kang, Hwirang;Dang, Ngoc Son;Lee, Deokkeun
    • Smart Structures and Systems
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    • v.20 no.6
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    • pp.697-708
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    • 2017
  • Maintenance plays a critical role in the bridge industry, but actual practices show many limitations because of traditional, 2D-based information systems. It is necessary to develop a new generation of maintenance information management systems for more reliable decision making in bridge maintenance. Enhancing current work processes requires a BIM-based 3D digital model that can use information from the whole lifecycle of a project (design, construction, operation, and maintenance) through continuous exchanges and updates from each stakeholder. This study describes the development of a data scheme for maintenance of cable-stayed bridges. We implemented the proposed system for a cable-stayed bridge and discussed its effectiveness.

A Study on Dynaniic Analysis for Earthquake Design of cable-stayed Bridges (사장교의 내진설계를 위한 동적해석에 관한 연구)

  • 이진휴;이재영;이장춘
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.36 no.1
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    • pp.103-115
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    • 1994
  • The dynamic earthquake analysis of plane cable-stayed bridge structures was formulated and implemented into a computer program which analyzes plane cable-stayed bridge structu- res subjected to initial cable tensions, member dead and live loads and seismic loads. Cable-stayed bridges were modelled as multi-degrees of freedom systems with lumped- mass. Various earthquake responses such as dynamic deflection, bending moment, shear force and cable tension were investigated by the dynamic analyses in the form of the time history analysis. The time history analysis was based on the mode superposition method. The study revealed that Fan-l type cable-syayed bridges is generally superior to other types for the earthquake proof even though aspects of deflection and section force of each type presents respective advantages and disadvantages. The study provided a method to design the sections of cable-stayed bridges under seismic loads with various design parameters related to structural types. The study is expected to be useful for effective design of cable-stayed bridges with conside- ration of earthquake.

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Static behaviors of self-anchored and partially earth-anchored long-span cable-stayed bridges

  • Xie, Xu;Yamaguchi, Hiroki;Nagai, Masatsugu
    • Structural Engineering and Mechanics
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    • v.5 no.6
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    • pp.767-774
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    • 1997
  • In this paper, three dimensional static behaviors of the self-anchored and partially earth-anchored cable-stayed bridges, with a span of 1400 meters, under wind loading are studied by using a 3D geometrical nonlinear analysis. In this analysis, the bridges both after completion and under construction are dealt with. The wind resistant characteristics of the both cable-stayed systems are made clear. In particular, the characteristics of the partially earth-anchored cable systems, which is expected to be a promising solution for extending the span of the cable-stayed systems further, is presented.

Field application of elasto-magnetic stress sensors for monitoring of cable tension force in cable-stayed bridges

  • Yim, Jinsuk;Wang, Ming L.;Shin, Sung Woo;Yun, Chung-Bang;Jung, Hyung-Jo;Kim, Jeong-Tae;Eem, Seung-Hyun
    • Smart Structures and Systems
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    • v.12 no.3_4
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    • pp.465-482
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    • 2013
  • Recently, a novel stress sensor, which utilizes the elasto-magnetic (EM) effect of ferromagnetic materials, has been developed to measure stress in steel cables and wires. In this study, the effectiveness of this EM based stress sensors for monitoring of the cable tension force of a real scale cable-stayed bridge was investigated. Two EM stress sensors were installed on two selected multi-strand cables in Hwa-Myung Bridge, Busan, South Korea. Conventional lift-off test was conducted to obtain reference cable tension forces of two test cables. The reference forces were used to calibrate and validate cable tension force measurements from the EM sensors. Tension force variations of two test cables during the second tensioning work on Hwa-Myung Bridge were monitored using the EM sensors. Numerical simulations were conducted to compare and verify the monitoring results. Based on the results, the effectiveness of EM sensors for accurate field monitoring of the cable tension force of cable-stayed bridge is discussed.