• Title/Summary/Keyword: cable stiffness

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A Study on Dynamic Characteristic of Robot Cables (로봇 케이블의 동적 특성에 관한 연구)

  • Kim, Jin Kyu;Kim, Jae Bong;Kang, Dae Sun;Choi, Woong Sub;Kim, Moon Young;Lee, Sang Beom;Yim, Hong Jae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.495-499
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    • 2014
  • In this study, the finite element modeling for the signal cable and pneumatic hose of the industrial robot is developed. The modulus of elasticity of signal cable and pneumatic hose is predicted by deflection test. Finite element model for the signal cable and pneumatic hose is developed by using the modulus of elasticity obtained from the tests. The developed finite element model is estimated through the vibration analysis. This study shows that the developed finite element model can be effectively utilized in the dynamic analysis.

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LRB-based Hybrid Base Isolation Systems for Seismically Excited Cable-Stayed Bridges (지진하중을 받는 사장교를 위한 LRB-기반 복합 기초격리 시스템)

  • 정형조;박규식;이헌재;이인원
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.527-534
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    • 2003
  • This paper presents the LRB-based hybrid base isolation systems employing additional active/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 hydraulic actuators (HAs) and ideal magnetorheological dampers (MRDs) are considered as additional active and semiactive control devices, respectively. Numerical simulation results show that all the hybrid base isolation systems are 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 MRBs is robust to the stiffness uncertainty of the structure, while the hybrid system with active HAs is not. Therefore, the LRB-based hybrid base isolation system employing MRDs could be more appropriate in real applications for full-scale civil infrastructures.

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The Shape Optimization of Cable Dome Using Real Coding Genetic Algorithm (실수코팅 유전알고리즘을 이용한 케이블 돔의 형상 최적 설계)

  • 한상을;조남철;김종범
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.177-184
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    • 2003
  • The purposes of this study are to develop the real coding genetic algorithm and to obtain the shape optimization of a cable domes by using this scheme. Generally, the structural performance of the cable dome is influenced very sensitively by prestress, geometry and length of the mast because of flexible structures. So, it is very important to decide the optimum shape to get maximum stiffness of cable domes. We use the two models to verify the usefulness of this algorithm for shape optimization and analyze the roof system of Seoul olympic gymnastic arena as one analytical model of practical structures

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Static analysis of a radially retractable hybrid grid shell in the closed position

  • Cai, Jianguo;Jiang, Chao;Deng, Xiaowei;Feng, Jian;Xu, Yixiang
    • Steel and Composite Structures
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    • v.18 no.6
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    • pp.1391-1404
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    • 2015
  • A radially retractable roof structure based on the concept of the hybrid grid shell is proposed in this paper. The single-layer steel trusses of the radially foldable bar structure are diagonally stiffened by cables, which leads to a single-layer lattice shell with triangular mesh. Then comparison between the static behavior between the retractable hybrid grid shell and the corresponding foldable bar shell with quadrangular mesh is discussed. Moreover, the effects of different structural parameters, such as the rise-to-span ratio, the bar cross section area and the pre-stress of the cables, on the structural behaviors are investigated. The results show that prestressed cables can strengthen the foldable bar shell with quadrangular mesh. Higher structural stiffness is anticipated by introducing cables into the hybrid system. When the rise-span ratio is equal to 0.2, where the joint displacement reaches the minimal value, the structure shape of the hyrbid grid shell approaches the reasonable arch axis. The increase of the section of steel bars contributes a lot to the integrity stiffness of the structure. Increasing cable sections would enhance the structure stiffness, but it contributes little to axial forces in structural members. And the level of cable prestress has slight influence on the joint displacements and member forces.

Dynamic Nonlinear Analysis of Marine Cables Under Wave Force and Earthquake Force (파랑하중 및 지진하중을 받는 해양케이블의 동적 비선형 해석)

  • 김문영
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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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.

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Nonlinear Dynamic Analysis on Low-Tension Towed Cable by Finite Difference Method (유한차분법을 이용한 저장력 예인케이블의 비선형 동적해석)

  • Han-Il Park;Dong-Ho Jung
    • Journal of the Society of Naval Architects of Korea
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    • v.39 no.1
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    • pp.28-37
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    • 2002
  • In this study nonlinear dynamic behaviors of towed tow-tension cables are numerically analysed. In the case of a taut cable analysis, a bending stiffness term is usually neglected due to its minor effect but it plays an important role in a low-tension cable analysis. A low-tension cable may experience large displacements due to relatively small restoring forces and thus the effects of fluid and geometric non-linearities become predominant. The bending stiffness and non-linearity effects are considered in this work. In order to obtain dynamic behaviors of a towed low-tension cable, three-dimensional nonlinear dynamic equation is described and discretized by employing a finite difference method. An implicit method and Newton-Raphson iteration are adopted for the time integration and nonlinear solutions. For the calculation of huge size of matrices. block tri-diagonal matrix method is applied, which is much faster than the well-known Gauss-Jordan method in two point boundary value problems. Some case studies are carried out and the results of numerical simulations are compared with those of a in-house program of WHOI Cable with good agreements.

Analysis Method for Cable-Membrane Structures with Element Slipping (외력에 의해 요소이동이 발생되는 케이블-막 구조물의 해석 방법)

  • Kang, Joo-Won;Kim, Jae-Yeol
    • Journal of Korean Association for Spatial Structures
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    • v.5 no.4
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    • pp.79-90
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    • 2005
  • The purpose of this study is development of a finite element algorithm to 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 Arbitrarily-Lagrangian-Eulerian(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. Various examples for cable and membrane structures are presented to verify the program's validation. The results are shown good agreement with that of existed one.

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Response evaluation and vibration control of a transmission tower-line system in mountain areas subjected to cable rupture

  • Chen, Bo;Wu, Jingbo;Ouyang, Yiqin;Yang, Deng
    • Structural Monitoring and Maintenance
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    • v.5 no.1
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    • pp.151-171
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    • 2018
  • Transmission tower-line systems are commonly slender and generally possess a small stiffness and low structural damping. They are prone to impulsive excitations induced by cable rupture and may experience strong vibration. Excessive deformation and vibration of a transmission tower-line system subjected to cable rupture may induce a local destruction and even failure event. A little work has yet been carried out to evaluate the performance of transmission tower-line systems in mountain areas subjected to cable rupture. In addition, the control for cable rupture induced vibration of a transmission tower-line system has not been systematically conducted. In this regard, the dynamic response analysis of a transmission tower-line system in mountain areas subjected to cable rupture is conducted. Furthermore, the feasibility of using viscous fluid dampers to suppress the cable rupture-induced vibration is also investigated. The three dimensional (3D) finite element (FE) model of a transmission tower-line system is first established and the mathematical model of a mountain is developed to describe the equivalent scale and configuration of a mountain. The model of a tower-line-mountain system is developed by taking a real transmission tower-line system constructed in China as an example. The mechanical model for the dynamic interaction between the ground and transmission lines is proposed and the mechanical model of a viscous fluid damper is also presented. The equations of motion of the transmission tower-line system subjected to cable rupture without/with viscous fluid dampers are established. The field measurement is carried out to verify the analytical FE model and determine the damping ratios of the example transmission tower-line system. The dynamic analysis of the tower-line system is carried out to investigate structural performance under cable rupture and the validity of the proposed control approach based on viscous fluid dampers is examined. The made observations demonstrate that cable rupture may induce strong structural vibration and the implementation of viscous fluid dampers with optimal parameters can effectively suppress structural responses.

A Study on Impact Sound Insulation Properties of EPDM Micro Cellular Pad (에틸렌-프로필렌-디엔 삼원 공중합 (EPDM) 발포체의 충격음 저감 특성에 관한 연구)

  • Lee, Kyung-Won;Lee, Jung-Hee;Sohn, Ho-Soung
    • Elastomers and Composites
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    • v.35 no.2
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    • pp.138-148
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    • 2000
  • In order to investigate the possibility of EPDM micro cellular pad (MCP) as an impact sound insulation product, we studied static/dynamic properties and vibration transfer characteristics of EPDM MCP depending on shape, thickness, degrees of foaming by using material test system (MTS) and lab scale mock-up test apparatus. Static/dynamic rigidity is increased when shape is simple. thickness and degrees of foaming low. We could see that dynamic stiffness is proportional to the transmissibility of EPDM MCP. When dynamic stiffness is increased, characteristic peak at transmissibility curve moves high frequency range or snows increase of maximum value of transmissibility. For lab scale mock-up test and finite element method, EPDM MCP shows low vibration velocity and superior mode shape to just concrete plus slab structure. We could confirm that possibility of EPDM MCP as a impact sound insulation product is high.

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Cable-pulley brace to improve story drift distribution of MRFs with large openings

  • Zahrai, Seyed Mehdi;Mousavi, Seyed Amin
    • Steel and Composite Structures
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    • v.21 no.4
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    • pp.863-882
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    • 2016
  • This study aims to introduce a new bracing system by which even super-wide frames with large openings can be braced. The proposed system, hereafter called Cable-Pulley Brace (CPB), is a tension-only bracing system with a rectilinear configuration. In CPB, a wire rope passes through a rectilinear path around the opening(s) and connects the lower corner of the frame to its opposite upper one. CPB is a secondary load resisting system with a nonlinear-elastic hysteretic behavior due to its initial pre-tension load. As a result, the required energy dissipation would be provided by the MRF itself, and the main intention of using CPB is to contribute to the initial and post-yield stiffness of the whole system. Using a stiffness calibration technique, optimum placement of the CPBs is discussed to yield a uniform displacement demand along the height of the structure. A displacement-based design procedure is proposed by which the MRF with CPB can be designed to achieve a uniform distribution of inter-story drifts with predefined values. Obtained results indicated that CPB leads to significant reductions in maximum and residual deformations of the MRF at the expense of minor increase in the maximum base shear and developed axial force demands in the columns. In the case of a typical 5-story residential building, compared to SMRF system, CPB system reduces maximum amounts of inter-story and residual drifts by 35% and 70%, respectively. Moreover, openings of the frame are not interrupted by the CPB. This is the most appealing feature of the proposed bracing system from architectural point of view.