• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.292-299
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• 1999

In order to investigate dynamic behaviors of marine cables under wave and earthquake forces a geometric nonlinear. F, E formulation of marine cables is presented and tangent stiffness and mass matrices for the isoparametric cable element are derived, The initial equilibrium state of cables subjected to self -weights and current forces is determined and free vibration and dynamic nonlinear analysis of cable structures under additional environmental loads are performed based on the initial configuration Challenging examples are presented and discussed in order to demonstrate the feasibility of the present finite element method and investigate dynamic nonlinear behaviors of marine cables.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.113-120
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• 2010

Recently, various evaluations concerning structural stability under construction step and completely constructed step have been executed during a Long-span Arch Bridge designing procedure. However, the breakage of cable-hangers of arched bridge in unexpected accident or periodic cable-replacement has not been considered. Therefore, the purpose of this study is that analyzing structural safety of arched bridge when the cable-hangers being fractured by that reasons. Dynamic analysis are performed by idealizing impact load to three types of impact functions as fracturing the cables. Consequently, when the hangers are fractured, the maximum tensile force by dynamic analysis is larger than those by static analysis. Therefore, the dynamic analysis is demanded to accurately obtain the responses for the structural stability with a realistic impact loading model in the breakage and replacement of cable hangers of long-span arched bride. Moreover, the analysis method and results in this study can be used to basic criteria in design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.1 s.53
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• pp.205-213
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• 2009

This study was planned to develop monitoring system of cable force to resolve cable force of cable-stayed bridge efficiently in a long-term plan. In the proposed monitoring system, firstly data are sampled from real-time acceleration record, secondly these sampled data are frequency analyzed by using the FFT(Fast Fourier Transform) algorism and lastly the analyzed results are averaged and generalized. For evaluating the applicability of this monitoring system, field loading test has performed in real cable-stayed bridge. In comparison with cable force by field manual calculation and cable force of monitoring system by semi-automatic calculation, the difference of calculated cable forces has within 1% error range and it is acceptable range. Additionally within negligible 5% error range of difference has occur between field manual calculation and monitoring system by automatic calculation. so monitoring system in this study has been verified to be reliable.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.1
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• pp.25-38
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• 1993

Numerical models of directional wave spectra for the analysis of offshore structural cable responses are verified. Alternative spreading models are used to predict wave-induced flows in water and for mooring systems. Hydrodynamic wave forces upon cable are estimated. using a Morison formula encompassing considerations for drag and for inertial forces both parallel and tangential to the slope of the cable. Numerical analysis for directional random waves. including consideration of displacement and velocity, trajectory, phase plane response. and tension are shown for mooring system cable responses at both the tether point for a buoy and at the anchor point. The effects of wave forces far different drag coefficients, various significant wave heights, and selected wave parameters are considered in the analysis. For the specific systems considered in the examples, it is demonstrated that wave period and height as well as wave spreading function parameters and drag coefficients, have an important effect upon the dynamic responses of the cable-buoy systems.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.198-203
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• 2004

Ocean developments gradually move to deep-sea in the 21 century. A deep-sea unmanned underwater vehicle is one of important tools for ocean resource survey. A marine cable plays an important role for the safe operation and signal transmission of a deep-sea unmanned underwater vehicle. The first cable of a deep-sea unmanned underwater vehicle is excited by surface vessel motion and shows non-linear dynamic behaviors. A ROV launcher is also excited by the 1st cable motion. A numerical method is necessary for analysing the dynamic behaviour of the first marine cable and the ROV launcher. In this study, a numerival program is appled to a 6,000m long cable for a deep-sea unmanned underwater vehicle to shaw shows the dynamic behaviour of the cable and the ROV launcher under combined excitations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.5
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• pp.1-12
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• 2018

This study presents the seismic response characteristics of domestic cable-supported bridges due to 3 earthquakes with magnitudes of 5.1, 5.8, and 4.5 in Richter scale, which occurred around Gyeongju region in 2016. The seismic acceleration response signals, recorded by the seismic acceleration sensors at the free field near bridge and designated positions on bridge, are utilized to characterize the seismic responses of structural elements of cable-supported bridges. The dynamic behaviors of bridges are presented through Fourier transform of acceleration time history. Using the peak accelerations normalized by those at the free fields, amplification effects on the tops of the pylons are analyzed comparatively bridge by bridge. Using aforementioned analyses, the necessity of development on the creteria of alert levels is discussed for the earthquake disaster response of cable-supported bridges.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.473-480
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• 2005

Geometrical non-linearity due to the flexibility of cables must be considered efficiently in the dynamic analysis of cable structures. In this paper, formulation of tangent stiffness matrix of elastic catenary cable is derived by using relative nodal displacements, self-weight and unstressed cable length. Free vibration analysis of simply supported cable using elastic catenary cable elements is conducted and compared with that using truss elements. The result shows that elastic catenary cable elements are more compatible than truss elements in the case of analysis of cable structures. Furthermore, the characteristic of dynamic behaviors of cable structures by temporary unstability phenomenon is confirmed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.61-68
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• 2003

Cable domes deform very largely because of the characteristics of flexible hybrid system and pre-tension, and include geometrical non-linearity in those structural behavior. Especially wind load is more dominant than seismic loads, because cable domes are flexible structures whose stiffness is very small and self-weight is very light. Therefore, in this paper, Modified Stiffly Stable Method is applied to analyze the nonlinear dynamic behavior of cable domes and compared these results with ones of Newmark-β Method which is generally used. The Seoul Olympic Gymnastic Arena is taken as an numerical example and three kinds of models with giving each different intensity of pre-tension are selected. And dynamic nonlinear behavior of cable domes are analyzed by artificial spectrum of wind velocity wave which is similar to actual wind loads.

• Proceeding of KASS Symposium
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• 2005.05a
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• pp.167-172
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• 2005

In the dynamic analysis of cable structures, geometrical non-linearity due to the flexibility of cables must be considered efficiently. In this paper, formulation of tangent stiffness matrix of elastic catenary cable is derived by using relative nodal displacements, self-weight and unstressed cable length. Free vibration analysis of simply supported cable using elastic catenary cable elements is conducted and compared with that using truss elements. The result shows that elastic catenary cable elements are more compatible than truss elements in the case of analysis of cable structures. Furthermore, the characteristic of dynamic behaviors of cable structures by temporary unstability phenomenon is confirmed.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.5
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• pp.375-387
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• 2023

The subsea power cables are increasingly important for harvesting renewable energies as we develop offshore wind farms located at a long distance from shore. Particularly, the continuous flexural motion of inter-array dynamic power cable of floating offshore wind turbine causes tremendous fatigue damages on the cable. As the subsea power cable consists of the helical structures with various components unlike a mooring line and a steel pipe riser, the fatigue analysis of the cables should be performed using special procedures that consider stick/slip phenomenon. This phenomenon occurs between inner helically wound components when they are tensioned or compressed by environmental loads and the floater motions. In particular, Vortex-induced vibration (VIV) can be generated by currents and have significant impacts on the fatigue life of the cable. In this study, the procedure for VIV fatigue analysis of the dynamic power cable has been established. Additionally, the respective roles of programs employed and required inputs and outputs are explained in detail. Demonstrations of case studies are provided under severely sheared currents to investigate the influences on amplitude variations of dynamic power cables caused by the excitation of high mode numbers. Finally, sensitivity studies have been performed to compare dynamic cable design parameters, specifically, structural damping ratio, higher order harmonics, and lift coefficients tables. In the future, one of the fundamental assumptions to assess the VIV response will be examined in detail, namely a narrow-banded Gaussian process derived from the VIV amplitudes. Although this approach is consistent with current industry standards, the level of consistency and the potential errors between the Gaussian process and the fatigue damage generated from deterministic time-domain results are to be confirmed to verify VIV fatigue analysis procedure for slender marine structures.