• Title, Summary, Keyword: cable stiffness

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A Study on the Slipping Problem for Cable-Membrane Structures (케이블-막구조물의 요소이동(slip)에 관한 연구)

  • Kim, Jae-Yeol;Kang, Joo-Won;Park, Sang-Min
    • Journal of Korean Association for Spatial Structures
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    • v.8 no.5
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    • pp.95-105
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    • 2008
  • The objective of this study is find out the stressed condition, slipped direction and slipped dimension when some elements of cable-membrane structures are slipped from it's initially designed coordinates by external loads as wind or non uniform load and so on. In order to search the slipped behaviors of cable-membrane structures, a ALE finite element formulation is introduced. In these procedures, a stiffness matrix related with ALE concept is formulated and a FE analysis program for cable-membrane structures with slipped elements is developed.

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Seismic Protection of Cable-stayed Bridges Using LRB and MR Damper (납-고무받침과 자기유변유체 감쇠기를 이용한 사장교의 내진제어)

  • 정형조;박규식;이인원
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.241-245
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    • 2003
  • This paper presents the LRB-based hybrid base isolation system employing additional semiactive control devices for seismic protection of cable-stayed bridges by examining the ASCE first generation benchmark problem for a cable-stayed bridge. In this study, ideal magnetorheological dampers (MRDs) are considered as additional semiactive control devices. Numerical simulation results show that the hybrid base isolation system is effective in reducing the structural responses of the benchmark cable-stayed bridge under the historical earthquakes considered. The simulation results also demonstrate that the hybrid base Isolation system employing semiactive MRDs is robust to the stiffness uncertainty of the structure. Therefore, the LRB-based hybrid base isolation system employing MRDs could be appropriate in real applications for full-scale civil infrastructures.

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Geometrically Nonlinear Dynamic Analysis of Cable Domes (케이블 돔의 기하학적 비선형 동적해석)

  • 한상을;서준호;김종범
    • Proceedings of the Computational Structural Engineering Institute Conference
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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.

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Impact of cable sag on the efficiency of an inertial mass damper in controlling stay cable vibrations

  • Wang, Zhi-hao;Gao, Hui;Xu, Yan-wei;Chen, Zheng-qing;Wang, Hao
    • Smart Structures and Systems
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    • v.24 no.1
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    • pp.83-94
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    • 2019
  • Passive negative stiffness dampers (NSDs) that possess superior energy dissipation abilities, have been proved to be more efficient than commonly adopted passive viscous dampers in controlling stay cable vibrations. Recently, inertial mass dampers (IMDs) have attracted extensive attentions since their properties are similar to NSDs. It has been theoretically predicted that superior supplemental damping can be generated for a taut cable with an IMD. This paper aims to theoretically investigate the impact of the cable sag on the efficiency of an IMD in controlling stay cable vibrations, and experimentally validate superior vibration mitigation performance of the IMD. Both the numerical and asymptotic solutions were obtained for an inclined sag cable with an IMD installed close to the cable end. Based on the asymptotic solution, the cable attainable maximum modal damping ratio and the corresponding optimal damping coefficient of the IMD were derived for a given inertial mass. An electromagnetic IMD (EIMD) with adjustable inertial mass was developed to investigate the effects of inertial mass and cable sag on the vibration mitigation performance of two model cables with different sags through series of first modal free vibration tests. The results show that the sag generally reduces the attainable first modal damping ratio of the cable with a passive viscous damper, while tends to increase the cable maximum attainable modal damping ratio provided by the IMD. The cable sag also decreases the optimum damping coefficient of the IMD when the inertial mass is less than its optimal value. The theoretically predicted first modal damping ratio of the cable with an IMD, taking into account the sag generally, agrees well with that identified from experimental results, while it will be significantly overestimated with a taut-cable model, especially for the cable with large sag.

Vibrational Characteristics on the Cables in Cable Stayed Bridge (사장교 케이블의 진동거동 특성)

  • Sung, Ikhyun
    • Journal of the Society of Disaster Information
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    • v.13 no.2
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    • pp.249-257
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    • 2017
  • Recently, a cable disconnection accident occurred due to a lightning strike at the Seohae Bridge located in Dangjin-Pyeongtaek City. This is a natural occurrence, but it is a recall that it is very important to review the safety issues due to the disconnection of cable bridges. In other words, the role of cables in cable bridges has a profound effect on the safety of the structure, and it has become necessary to grasp the effect on the entire structural system. The cable bridge is an economic bridge that builds the main tower and supports the bottom plate by cable. The influence of the cable is the main member, which is a big influence on the safety of the whole bridge system. 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. 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.

A Study on Stress Properties for Cable Anchorage zone of Cable Stayed Prestressed Concrete Box Girder (케이블로 지지된 프리스트레스트 콘크리트 박스거더 정착부의 응력특성에 관한 연구)

  • Tae, Ghi-Ho;Kim, Doo-Hwan;Byun, Yun-Joo;Song, Kwan Kwon
    • Journal of the Korean Society of Safety
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    • v.27 no.6
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    • pp.84-92
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    • 2012
  • Anchorage zone in prestressed concrete cable stayed bridges is very important area due to the more accurate analysis is needed to estimate the behavior. In the study, since the cable anchorage zone in the prestressed concrete cable-stayed bridge is subject to a large amount of concentrated tendon forces, it shows very complicated stress distributions and causes a serious local cracks. Accordingly, It is necessary to investigate the parameters of affecting the stress properties, such as the cable inclination, the position of anchor plate, the modeling method and the three dimensional effect. The tensile stress distribution of anchorage zone is compared to the actual design condition by varing the stiffness of spring element in the local modeling and an appropriate position of anchor plate is determined. These results would be elementary data to the stress state of anchorage zone and more efficient design.

A Numerical and Experimental Study on Dynamics of A Towed Low-Tension Cable

  • Jung, D.H.;Park, H.I.;Koterayama, W.
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.191-196
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    • 2002
  • The paper presents a numerical and experimental investigation on dynamic behaviors of a towed low tension cable. In the numerical study, an implicit finite difference algorithm is employed for three-dimensional cable equations. Fluid and geometric non-linearity and bending stiffness are considered and solved by Newton-Raphson iteration. Block tri-diagonal matrix method is applied for the fast calculation of the huge size of matrices. In order to verify the numerical results and to see real physical phenomena, an experiment is carried out for a 6m cable in a deep and long towing tank. The cable is towed in two different ways; one is towed at a constant speed and the other is towed at a constant speed with top end horizontal oscillations. Cable tension and shear forces are measured at the top end. Numerical and experimental results are compared with good agreements in most cases but with some differences in a few cases. The differences are due to drag coefficients caused by vortex shedding. In the numerical modeling, non-uniform element length needs to be employed to cope with the sharp variation of tension and shear forces at near top end.

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Geometric nonlinear analysis of steel structures with external pretension using the multi-noded cable element (다절점 케이블요소를 이용한 외부 긴장된 강구조 시스템의 기하학적 비선형해석)

  • Lee, Jun Seok;Kim, Moon Young;Han, Man Yop;Kim, Sung Bo;Kim, Nak Kyung
    • Journal of Korean Society of Steel Construction
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    • v.18 no.6
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    • pp.727-735
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    • 2006
  • In this paper, a geometric nonlinear analysis procedure of the beam-column element including multi-noded cable element in extension of companion paper (Kim et al., 2005) is presented. First, a stiffness matrix was derived about the beam-column element that considers the second effect of the initial force supposing the curved shape at each time-step, with Hermitian polynomials as the shape function. Second, the multi-noded cable element was also subjected to the tangent stiffness matrix. To verify the geometric nonlinearity of this newly developed multi-noded cable-truss element, the Innovative Prestressed Support (IPS) system using this theory was analysed by geometric nonlinear method and the results were compared with those produced by linear analysis.

Seismic Behavior Analysis of the Bridge Retrofitted by Restrainer (Restrainer로 보강된 교량시스템의 지진거동분석)

  • 김상효;마호성;이상우;원정훈
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.289-296
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    • 2000
  • Dynamic responses of a bridge retrofitted with cable restrainers are examined under seismic excitations. A simplified and idealized mechanical model is developed to analyze the effects of the restrainers, which can consider the plastic behavior as well as the fracture of the cable. Using the proposed model, the effects of the stiffness and the clearance length of the restrainer upon the global bridge seismic behaviors are estimated. The changes of pounding forces, shear forces, and bending moments due to the application of restrainers are also investigated. The main effect of restrainers upon global bridge motions is found to reduce the relative distances between adjacent vibrations units. It is also found that the relative distances are decreased as the clearance length of the restrainer decreases and the stiffness of restrainer increases.

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Stability Analysis of Steel Cable-stayed Bridges under Construction Stage (폐합 전 강사장교의 안정성 해석)

  • Kim, Seung-Jun;Shim, Kyung-Suk;Won, Deok-Hee;Cho, Sun-Kyu;Kang, Young-Jong
    • Journal of Korean Society of Steel Construction
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    • v.23 no.1
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    • pp.99-111
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    • 2011
  • This paper presents an investigation of the structural stability of cable-stayed bridges in the construction stage, using geometric nonlinear finite-element analysis and considering various geometric nonlinearities, such as the sag effect of the cables, the P-${\Delta}$ effects of the girder and mast, and the large displacement effect. Initial shape analysis and construction-stage analysis were performed to determine the equilibrium of the structure in the construction stage. After that, geometric nonlinear analysis was performed to study structural stability. In this study, the weight of the derrick crane and the key segment were considered the main external loads, which were applied to the tip of the center span. The cable arrangement type and the stiffness ratios of the girder and mast were considered the main parameters of the analytic research. Based on the results of the analysis, the change in the buckling mode and critical load factors with respect to the cable arrangement type and the stiffness ratios of the girder and mast was investigated. The buckling modes of the steel cable-stayed bridges in the construction stage were classified, and the ranges of the stiffness ratios of the girder and mast, which show these classified buckling modes, were suggested.