• 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.

• Smart Structures and Systems
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• v.18 no.1
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• pp.17-29
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• 2016

In this paper, the possibility of using human induced loading (HIL) to detect a decrease of tension in the cable-stays of an existing footbridge is investigated. First, a reliable finite elements model of an existing footbridge is developed by calibration with experimental data. Next, estimates of the tension in the cables are derived and their dependency on the modal features of the deck is investigated. The modelling of the HIL is briefly discussed and used to perform the nonlinear, large strain, dynamic finite elements analyses. The results of these analyses are assessed with focus on characterizing the time histories of the tension in the cables under pedestrian crossing and their effects on the deck response for different initial conditions. Finally, the control perspective is introduced in view of further research.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.1031-1038
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• 2002

In this paper the erection method of the Seohae Bridge starter is presented. The erection method of starter for cable stayed bridge was changed from conventional bracket supported erection to heavy lifting supported directly by stays. There was the need to reduce the erection time drastically. The cost saving was obtained as a bonus.

• Structural Engineering and Mechanics
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• v.85 no.1
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• pp.81-88
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• 2023

This paper begins by analyzing cable vibrations due to external excitations and their effects on the overall dynamic behavior of cable-stayed bridges. It is concluded that if the natural frequency of a cable approaches any natural frequency of the bridge, the cable loses its rigidity and functionality. The results of this analysis explain the phenomenon that occurred on the Dubrovnik Bridge in Croatia during a storm and measures for its retrofit. A field test was conducted before the bridge was opened to traffic. It was concluded: "The Bridge excited unpleasant transverse superstructure vibration with the frequency of approximately 0.470 Hz. Hence, it seems possible that a pair of stays vibrating in phase may excite deck vibrations". Soon after this Bridge opened, a storm dumped heavy damp snow in the area, causing the six longest cable stay pairs of the main span to undergo large-amplitude vibrations, and the superstructure underwent considerable displacements in combined torsion-sway and bending modes. This necessitated rehabilitation measures for the Bridge including devices to suppress the large-amplitude vibrations of cables. The rehabilitation and monitoring of the Bridge are also presented here.

• Journal of the Korean Society for Railway
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• v.2 no.3
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• pp.36-45
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• 1999

The basic idea of cable-stayed girder bridges is the utilization of high strength cables to provide intermediate supports for the bridge girder so that the girder can span a much longer distance. 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. Techniques required for the static analysis of cable-stayed bridges has been developed by many researchers. However, little work has been done on the dynamic analysis of such structures. To investigate the characteristics of the dynamic response of long-span cable-stayed bridges due to various dynamic loadings likes moving traffic loads. two different 3-D cable-stayed bridge models are considered in this study. Two models are exactly the same in structural configurations but different in finite element discretization. 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.

• Wind and Structures
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• v.6 no.6
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• pp.471-484
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• 2003

The rain-wind induced vibration of stays is a phenomenon discovered recently and not well explained yet. As it is influenced by a wide range of physical parameters (cable size and shape, wind speed, direction and turbulence, rain intensity, material repellency and roughness, cable weight, damping and pre-strain), this peculiar phenomenon is difficult to reproduce in laboratory controlled conditions. A successful wind tunnel experimental campaign, in which some basic physical quantities were measured, allowed an extensive analysis as to identify the parameters of the rain-wind induced excitation. The unsteady pressure field and water thickness around a cable model were measured under rainy-excited conditions. The knowledge of those parameters provided helpful information about the air-flow around the cable and allowed to clarify the physical phenomenon which produces the excitation.

• Coupled systems mechanics
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• v.3 no.4
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• pp.345-365
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• 2014

A significant problem met in engineering practice when designing cable-stayed bridges is the failure of cables. Many different factors can lead to sudden failure of cables, such as corrosion, continuous friction or abrasion, progressive and extended crevice created by fatigue and finally an explosion caused by sabotage or accident, are some of the causes that can lead to the sudden failure of one or more cables. This paper deals with the sudden failure of cables in a special form of cable-stayed bridges with a single line of cables anchored at the central axis of the deck's cross-section. The analysis is carried out by the modal superposition technique where an analytical method developed by the authors in a previous work has been employed.

• Earthquakes and Structures
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• v.8 no.5
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• pp.1113-1126
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• 2015

A damage localization algorithm based on Operational Deformed Shapes and known as Interpolation Damage Detection Method, is herein applied to the finite element model of a cable stayed bridge for detecting and localizing damages in the stays and the supporting steel beams under the bridge deck. Frequency Response Functions have been calculated basing on the responses of the bridge model to low intensity seismic excitations and used to recover the Operational Deformed Shapes both in the transversal and in the vertical direction. The analyses have been carried in the undamaged configuration and repeated in several different damaged configurations. Results show that the method is able to detect the damage and its correct location, provided an accurate estimation of the Operational Deformed Shapes is available. Furthermore, the damage detection algorithm results effective also when damages coexist at the same time at several location of the cable-stayed bridge members.

• Steel and Composite Structures
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• v.20 no.2
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• pp.447-468
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• 2016

Despite of the growing number of built examples, the analysis of non-symmetrical cable-stayed bridges has not received considerable attention from the researchers. In fact, the effects of the main design parameters in the structural behavior of these bridges are not addressed in detail in the literature. To fill this gap, this paper studies the structural response of a number of non-symmetrical cable-stayed bridges. With this aim, a parametric analysis is performed to evaluate the effect of each of the main design parameters (the ratio between the main and the back span length, the pylon, the deck and backstay stiffnesses, the pylon inclination, and the stay configuration) of this kind of bridges. Furthermore, the role of the geometrical nonlinearity and the steel consumption in stays are evaluated.

• Wind and Structures
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• v.6 no.6
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• pp.485-498
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• 2003

This paper presents a mechanical model of Rain-Wind Induced Vibration (RWIV) of stay cables. It is based on the physical interpretation of the phenomenon as given in Cosentino, et al. (2003, referred as Part I). The model takes into account all the main forces acting on cable, on the upper water rivulet (responsible of the excitation) and the cable-rivulet interaction. It is a simplified (cable cross-sectional and deterministic) representation of the actual (stochastic and three-dimensional) phenomenon. The cable is represented by its cross section and it is subjected to mechanical and aerodynamic (considering the rivulet influence) forces. The rivulet is supposed to oscillate along the cable circumference and it is subjected to inertial and gravity forces, pressure gradients and air-water-cable frictions. The model parameters are calibrated by fitting with experimental results. In order to validate the proposed model and its physical basis, different conditions (wind speed and direction, cable frequency, etc.) have been numerically investigated. The results, which are in very good agreement with the RWIV field observations, confirm the validity of the method and its engineering applicability (to evaluate the RWIV sensitivity of new stays or to retrofit the existing ones). Nevertheless, the practical use of the model probably requires a more accurate calibration of some parameters through new and specifically oriented wind tunnel tests.