• Journal of Korean Society of Steel Construction
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• v.23 no.2
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• pp.199-210
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• 2011

The cables in cable-stayed bridges are under high stress and are very sensitive to vibration due to their small section areas compared with other members. Therefore, it is reasonable to evaluate the cable impact factor by taking into account the dynamic effect due to moving-vehicle motion. In this study, the cable impact factors were evaluated via moving-vehicle-load analysis, considering the design parameters, i.e., vehicle weight, cable model, road surface roughness, vehicle speed, longitudinal distance between vehicles. For this purpose, two steel composite cable-stayed bridges with 230- and 540-m main spans were selected. The results of the analysis were then compared with those of the influence line method that is currently being used in design practice. The road surface roughness was randomly generated based on ISO 8608, and the convergence of impact factors according to the number of generated road surfaces was evaluated to improve the reliability of the results. A9-d.o.f. tractor-trailer vehicle was used, and the vehicle motion was derived from Lagrange's equation. 3D finite element models for the selected cable-stayed bridges were constructed with truss elements having equivalent moduli for the cables, and with beam elements for the girders and the pylons. The direct integration method was used for the analysis of the bridge-vehicle interaction, and the analysis was conducted iteratively until the displacement error rate of the bridge was within the specified tolerance. It was acknowledged that the influence line method, which cannot consider the dynamic effect due to moving-vehicle motion, could underestimate the impact factors of the end-cables at the side spans, unlike moving-vehicle-load analysis.

• Journal of the Korea Computer Industry Society
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• v.4 no.4
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• pp.579-588
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• 2003

There are many unfavorable conditions that lead to shortening life of cable by causing dielectric breakdown and aging such as field concentrations occurring in intermediate materials linking each cables, penetration of various impurities, and undermining of cable insulation layers. This paper simulated investigated partial discharge properties of XLPE which is widely used for ultra high voltage cable insulation materials and EPDM which is being used as insulation layer of cable joint materials kit, using Boundary Element Method. The result of computer simulation showed that inner-Void defect caused silicone oil to weaken the E-field effect. and we also found that E-field distribution in EPDM remained relatively lower than that in XLPE.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.3
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• pp.1-12
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• 1989

The nonlinearity of a cable-stayed bridge results from the large displacement of main girder due to a long span, the catenary action of cables and the flexural stiffness reduced by large axial forces. The dynamic behaviour of a cable-stayed bridge plays an important role in determining its safety. Especially, when the eccentrically moving load is applied to a cable-stayed bridge, the torsional vibration and vertical vibration are coupled and moreover the variation of cable tensions shows important dynamic characteristics. This dissertation presents a theoretical study and a finite element procedure for analysis of a cable-stayed bridge under a eccentrically moving load. Attention is focused on the dynamic behaviours such as dynamic increments of cable tensions and nodal displacements, with the variety of velocities and eccentricities of moving load. It is found that a moving load with eccentricity can have significant effects upon the responses; the torsion of bridge deck and the increments of cable tensions, according to the present results in this study.

• Journal of Aerospace System Engineering
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• v.16 no.4
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• pp.68-76
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• 2022

The purpose of this paper was to design the cable networks for mesh reflector antennas, considering the flexibility of structures. An effective form-find methodology is proposed. The whole parts of the cable networks are described by the absolute nodal coordinate formulation. Additionally, nonlinear deformation of the cable can be obtained. The form-finding analysis of the reflector with standard configuration is performed, to validate the proposed methodology. The truss ring structure is numerically modeled using the frame elements. To consider the flexibility of the truss ring as well as the cable net structure, an iteration analysis between the truss ring and the cable net under tensional forces is also performed in the form-finding process. The finial configuration of the reflector with tensioned cable networks is demonstrated.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.3
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• pp.195-202
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• 2012

Two nonlinear frame elements taking into account geometric nonlinearity is presented and compared based on the Lagrangian co-rotational formulation. The first frame element is believed to be geometrically-exact because not only tangent stiffness matrices is exactly evaluated including stiffness matrices due to initial deformation but also total member forces are directly determined from total deformations in the deformed state. Particularly two exact tangent stiffness matrices based on total Lagrangian and updated Lagrangian formulation, respectively, are verified to be identical. In the second frame element, the deformed curved shape is regarded as the polygon and current flexural deformations in iteration process are neglected in evaluating tangent stiffness matrices and total member forces. Two numerical examples are given to demonstrate the accuracy and the good performance of the first frame element compared with the second element. Furthermore it is shown that the first frame element can be used in tracing nonlinear behaviors of cable members.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.481-488
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• 2005

This study presents a elastic parabolic cable element for initial shaping analysis of cable structures. First, the compatibility condition and the tangent stiffness matrices of the elastic catenary cable element are shortly summarized. Next the force-deformation relations and the tangent stiffness matrices of the elastic parabolic cable elements are derived from the assumption that sag configuration under self-weights is small. To confirm the accuracy of this element, initial shaping analysis of cable-stayed bridges under dead loads is executed. Finally, the accuracy and the validity of the analysis-results are compared and analyzed through numerical examples.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.188-189
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• 2006

ITVDC 해저케이블의 절연은 주로 지절연물(紙絶緣物)에 고점도의 컴파운드를 강제함침(mass-impregnation)하여 제조된다. 이러한 강제 함침 작업은 제조 공정 중 가장 긴 시간이 소요되며, 케이블의 절연 특성을 결정하는 중요한 요소가 된다. 그러나 함침은 복잡한 물리현상이며, 함침이 진행되는 동안 케이블의 내부 상태를 직접 관찰하기 곤란하다. 따라서 기존의 제조 경험을 바탕으로 작업조건에 충분한 안전율을 적용하는 실정이다. 이와 같은 강제함침 작업조건을 합리화하면 공정에 소요되는 시간뿐 아니라 함침조건을 조정하여 케이블 절연 특성의 향상까지 기대할 수 있다. 본 논문에서는 당사가 HVDC 해저케이블 개발과정에서 함침에 관한 이론적 검토와 간이 함침실험을 통해 정립한 함침조건에 대해 기술하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2A
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• pp.85-95
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• 2012

This paper presents an investigation on the ultimate behavior of steel cable-stayed bridges using nonlinear finite element analysis method. Cable-stayed bridges exhibit various geometric nonlinearities as well as material nonlinearities, so rational nonlinear finite element analysis should be performed for investigation of the ultimate behavior. In this study, ultimate behavior of steel cable-stayed bridges was studied using rational ultimate analysis method. Nonlinear equivalent truss element and nonlinear frame element were used for modeling the cable, girder and mast. Moreover, refined plastic hinge method was adopted for considering the material nonlinearity of steel members. In this study, the 2-step analysis method was used. Before live load analysis, initial shape analysis was performed in order to consider the dead load condition. For investigation of the ultimate behavior of steel cable-stayed bridges, analysis models which span length is 920.0 m were used. Radiating type and fan type were considered as the cable-arrangement types. With various quantitative evidences such as load-displacement curves, deformed shapes, locations of the yield point or region, bending moment distribution and so on, the ultimate behavior of steel cable-stayed bridges was investigated and described in this paper.

• The Journal of the Convergence on Culture Technology
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• v.10 no.4
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• pp.473-481
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• 2024

In this paper, we introduce a newly developed winding model to simulate the motion of underwater cable consisting of winch drums. It is assumed that only tension affects the underwater cable motion. This assumption is suitable for simulating the underwater cable motion towed by a navel vessel in a straight ahead maneuver. The underwater cable is discretized using Nodal Position Finite Element Method. This numerical method is known to be suitable for predicting the underwater cable motion with large deformation because it can express geometric nonlinearity. In this paper, the validity of the numerical method was secured by comparing it with the depth information of towing cable measured through sea experiments.

• 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.