• Earthquakes and Structures
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• v.3 no.3_4
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• pp.271-295
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• 2012

This paper presents the solution scheme of using the continuous formulation of 1-D linear member for the dynamic analysis of structures consisting of axially loaded members. The context describes specific applications of such scheme to the verification of experimental data obtained from field test of bridges carried out by a microwave interferometer system and velocimeters. Attention is focused on analysis outlines that may be applicable to in-situ assessment for cable-stayed bridges. The derivation of the dynamic stiffness matrix of a prismatic member with distributed properties is briefly reviewed. A back calculation formula using frequencies of two arbitrary modes of vibration is next proposed to compute the tension force in cables. Derivation of the proposed formula is based on the formulation of an axially loaded flexural member. The applications of the formulation and the proposed formula are illustrated with a series of realistic examples.

• Structural Engineering and Mechanics
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• v.59 no.4
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• pp.621-652
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• 2016

A new cable-supported bridge model consisting of suspension parts, self-anchored cable-stayed parts and earth-anchored cable-stayed parts is presented. The new bridge model can be used for suspension bridges, cable-stayed bridges, cable-stayed suspension bridges, and partially earth-anchored cable-stayed bridges by varying parameters. Based on the assumption that each structural member is in either an axial compressive or tensile state, and the stress in each member is equal to the allowable stress of the material, the material quantity for each component is calculated. By introducing the unit cost of each type of material, the estimation formula for the cost of the new bridge model is developed. Numerical examples show that the results from the estimation formula agree well with that from the real projects. The span limit of cable supported bridge depends on the span-to-height ratio and the density-to-strength ratio of cables. Finally, a parametric study is illustrated aiming at the relations between three key geometrical parameters and the cost of the bridge model. The optimization of the new bridge model indicates that the self-anchored cable-stayed part is always the dominant part with the consideration of either the lowest total cost or the lowest unit cost. It is advisable to combine all three mentioned structural parts in super long span cable supported bridges to achieve the most excellent economic performance.

• 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.

• Structural Engineering and Mechanics
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• v.71 no.3
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• pp.271-282
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• 2019

The span record of cable-stayed bridges has exceeded 1,000 m, which makes research on the maximum possible span length of cable-stayed bridges an important topic in the engineering community. In this paper, span limit is discussed from two perspectives: the theoretical span limit determined by the strength-to-density ratio of the cable and girder, and the engineering span limit, which depends not only on the strength-to-density ratio of materials but also on the actual loading conditions. Closed form equations of both theoretical and engineering span limits of cable-stayed bridges determined by the cable and girder are derived and a detailed parametric analysis is conducted to assess the engineering span limit under current technical conditions. The results show that the engineering span limit of cable-stayed bridges is about 2,200 m based on materials used available today. The girder is the critical member restricting further increase in the span length; its compressive stress is the limiting factor. Approaches to increasing the engineering span limit are also presented based on the analysis results.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.427-434
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• 2002

• Journal of the Korean Society of Hazard Mitigation
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• v.3 no.4 s.11
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• pp.103-109
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• 2003

A numerical analysis of cable-stayed bridge is conducted to determine optimum longitudinal modulus of elasticity which represents the boundary condition between the tower and main girder. The effect of longitudinal modulus of elasticity is investigated for different loading condition (live load, wind load, seismic load), respectively. There are significant changes in the member forces as variations of longitudinal modulus of elasticity, such as, $k_h$=e=100tonf/m/bearing (live load), $k_h$=e=1000tonf/m/bearing (seismic load), However, the wind loads do not affect member forces. The optimum longitudinal modulus of elasticity is determined from considering minimum member forces in the numerical analysis results.

• Journal of Korean Society of Steel Construction
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• v.11 no.4 s.41
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• pp.351-362
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• 1999

Damage detection methods which utilize the change in dynamic characteristics are very hard to apply to large civil structures since local damage hardly affects global dynamic characteristics. But, if there is a very important and critical member and we focus only on the local behavior of it, it would be possible to detect damage from the change in local dynamic characteristics, such as natural frequencies and mode shapes .In this study, the cable anchorage part of a cable-stayed bridge under construction is modeled and analyzed by commercial finite element program, ABAQUS. It has both welding and bolting connections with a cable and a stiffening plate, and has a possible high stress concentration portions in it. Several damage scenarios such as crack through the welding or crack through the bolting connection are examined. The result shows that the local natural frequencies of the damaged member decrease up to 16% compared with that of the undamaged member. It is concluded that there is quite a high feasibility that the damage of the cable anchorage can be detected by measuring local dynamic characteristics.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.246-252
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• 2000

The nonlinearity of a cable-stayed bridge results in the large displacement of main girder due to a long span, the large axial forces reduce the catenary action of cables and the flexural stiffness. Therefore, the static and dynamic behavior of pylon for a cable-stayed bridge plays an important role in determining its safety. This study was performed to find the behavior of pylon of cable-stayed bridge for the first-order analysis considering of axial load only and for the second-order analysis considering of lateral deflection due to axial load. The axial force and moment values of pylon were different from the results of the first-order analysis and second-order analysis according to pylon shape and cross beam stiffness when the pylon was subjected to earthquake and wind loads. In the second-order analysis, comparing the numerical values of the member forces for the dynamic analysis, types 3 and 4 (A type) were relatively more advantageons types than types 1 and 2 (H type). Considering the stability for pylon of cable-stayed bridge (whole structural system), types 3 and 4 (A type) with pre-buckling of girder were proper types than types 1 and 2 (H type) with buckling of pylon.

• Wind and Structures
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• v.11 no.6
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• pp.441-453
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• 2008

In this study, a partially earth-anchored cable system is studied in order to reduce the dynamic wind response of cable-stayed bridges. The employment of earth-anchored cables changes the dynamic characteristics of cable-stayed bridges under wind loads. In order to estimate the changes in the member forces, the spectral analysis for wind buffeting loads are performed and the peak responses are evaluated using 3-D finite element models of the three-span cable-stayed bridges with the partially earth-anchored cable system and with the self-anchored cable system, respectively. Comparing the results for the two different models, it is found that the earth-anchored cables affect longitudinal and vertical modes of the bridge. The changes of the natural frequencies for the longitudinal modes remarkably decrease the peak bending moment in the pylon and the movements at the expansion joints. The small changes of the natural frequencies for the vertical modes slightly increase bending moments and deflections in the girder. The original effects of the partially earth-anchored cable system are also shown under wind loads; the decrement of girder axial forces and bearing uplifting forces, and the increment of cable forces in the earth-anchored cables.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.91-99
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• 2010

In this study, the advanced numerical algorithm is developed which can performed the static and dynamic stochastic finite element analysis by considering the effect of uncertainties included in the member stiffness of steel cable-stayed bridges and seismic load. After conducting the linear and nonlinear initial shape analysis, the advanced numerical algorithm is the assessment tool which can performed structural the response analysis considering the static linearity and non-linearity of before or after induced intial tensile force, and examined the reliability assessment more efficiently. The verification of the developed numerical algorithm is evaluated by analyzing the regression analysis and coefficient of correlation using the direct monte carlo simulation. Also, the dynamic response characteristic and coefficient of variation of the steel cable-stayed bridge is calculated by considering the uncertainty of random variables using the developed numerical algorithm. In addition, the quantitative structural safety of the steel cable-stayed bridges is evaluated by conducting the reliability assessment based upon the dynamic stochastic finite element analysis result.