• Title, Summary, Keyword: cable stiffness

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Development of Cable Damper System and Its Verification Test (사장교 케이블 댐퍼시스템 개발과 검증실험)

  • Seo, Ju-Won;Kim, Nam-Sik;Suh, Jeong-Gin;Jeong, Woon
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.394-402
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    • 2001
  • In order to lessen cable vibration, new cable damper system with high damping rubber was developed using the basis of the LRB design scheme. The analysis model of cable damper system incorporate voigt-kelvin damper model into the nonlinear cable analysis model. To achieve maximum damping capacity both reducing damper stiffness and developing high damping rubber were performed. As a result of verification test, the high damping rubber damper show its effectiveness in improving cable damping capacity.

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Mechanics feasibility of using CFRP cables in super long-span cable-stayed bridges

  • Zhang, Xin-Jun
    • Structural Engineering and Mechanics
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    • v.29 no.5
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    • pp.567-579
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    • 2008
  • To gain understanding of the applicability of CFRP cables in super long-span cable-stayed bridges, by taking a 1400 m cable-stayed bridge as example, mechanics performance including the static behavior under service load, dynamic behavior, wind stability and seismic behavior of the bridge using either steel or CFRP cables are investigated numerically and compared. The results show that viewed from the aspect of mechanics performance, the use of CFRP cables in super long-span cable-stayed bridges is feasible, and the cross-sectional areas of CFRP cables should be determined by the principle of equivalent axial stiffness.

Shape Optimization of the Cable Dome System (케이블 돔 시스템의 형상 최적화)

  • 조남철;최승열;한상을
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.151-160
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    • 2004
  • Genetic algorithm is the theory of grafting the principle of survival of the fittest in genetics on to the computer algorithm and it is used to solve the optimization problems, especially the shape and size optimization of the structure in Architectural problems. In the size optimization problem discrete variables are used, but series variables have to be used in the shape optimization problem because of the incongruenty. The purpose of this study is to obtain the optimum shape of cable domes by using the real coding genetic algorithm. Generally, the structural performance of the cable domes is influenced very sensitively by pre-stress, geometry and length of the mast because of its flexible characteristic. So, it is very important to decide the optimum shape to get maximum stiffness of cable domes. We use the model to verify the usefulness of this algorithm for shape optimization and analyze the roof system of Seoul Olympic Gymnastic Arena as analytical model of a practical structures. It is confirmed lastly that the optimum shape domes have more stiffness than initial shape ones.

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Stress analysis model for un-bonded umbilical cables

  • Chen, Xiqia;Fu, Shixiao;Song, Leijian;Zhong, Qian;Huang, Xiaoping
    • Ocean Systems Engineering
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    • v.3 no.2
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    • pp.97-122
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    • 2013
  • For the optimization design and strength evaluation of the umbilical cable, the calculation of cross section stress is of great importance and very time consuming. To calculate the cross section stress under combined tension and bending loads, a new integrated analytical model of umbilical cable is presented in this paper. Based on the Hook's law, the axial strain of helical components serves as the tensile stress. Considering the effects of friction between helical components, the bending stress is divided into elastic bending stress and friction stress. For the former, the elastic bending stress, the curvature of helical components is deduced; and for the latter, the shear stress before and after the slipping of helical components is determined. This new analytical model is validated by the experimental results of an umbilical cable. Further, this model is applied to estimate the extreme strength and fatigue life of the umbilical cable used in South China Sea.

Dynamic analysis of a cable-stayed bridge using continuous formulation of 1-D linear member

  • Yu, Chih-Peng;Cheng, Chia-Chi
    • 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.

Dry friction losses in axially loaded cables

  • Huang, Xiaolun;Vinogradov, Oleg G.
    • Structural Engineering and Mechanics
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    • v.4 no.3
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    • pp.330-344
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    • 1996
  • A model of a cable comprising interacting wires with dry friction forces at the interfaces is subjected to a quasi-static cyclic loading. The first cycle of this process, comprising of axial loading, unloading and reloading is investigated analytically. Explicit load-elongation relationships are obtained for all of the above phases of the cycle. An expression for the hysteretic losses is also obtained in an explicit form. It is shown that losses are proportional to the third power of the amplitude of the oscillating axial force, and are in inverse proportion to the interwire friction forces. The results obtained are used to introduce a model of a cable as a solid rod with an equivalent stiffness and damping properties of the rod material. It is shown that the stiffness of the equivalent rod is weakly nonlinear, whereas the viscous damping coefficient is proportional to the amplitude of the oscillation. Some numerical results illustrating the effect of cable parameters on the losses are given.

Design formulas for vibration control of taut cables using passive MR dampers

  • Duan, Yuanfeng;Ni, Yi-Qing;Zhang, Hongmei;Spencer, Billie.F. Jr.;Ko, Jan-Ming;Fang, Yi
    • Smart Structures and Systems
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    • v.23 no.6
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    • pp.521-536
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    • 2019
  • Using magnetorheological (MR) dampers in multiswitch open-loop control mode has been shown to be cost-effective for cable vibration mitigation. In this paper, a method for analyzing the damping performance of taut cables incorporating MR dampers in open-loop control mode is developed considering the effects of damping coefficient, damper stiffness, damper mass, and stiffness of the damper support. Making use of a three-element model of MR dampers and complex modal analysis, both numerical and asymptotic solutions are obtained. An analytical expression is obtained from the asymptotic solution to evaluate the equivalent damping ratio of the cable-damper system in the open-loop control mode. The individual and combined effects of the damping coefficient, damper stiffness, damper mass and stiffness of damper support on vibration control effectiveness are investigated in detail. The main thrust of the present study is to derive a general formula explicitly relating the normalized system damping ratio and the normalized damper parameters in consideration of all concerned effects, which can be easily used for the design of MR dampers to achieve optimal open-loop vibration control of taut cables.

A Multi-noded Cable Element Considering Sliding Effects (슬라이딩을 허용하는 다절점 케이블요소)

  • Kim, Moon Young;Lee, Jun Seok;Han, Man Yop;Kim, Sung Bo;Kim, Nak Kyung
    • Journal of Korean Society of Steel Construction
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    • v.17 no.4
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    • pp.449-457
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    • 2005
  • A multi-noded cable element allowing sliding at its nodes without frictions was introduced in this paper, and its elastic stiffness matrix was derived. A two-node truss element was briefly summarized and extended to multi-node, cable-truss elements that keep their tension constant but are connected without frictions through several nodes. The element elastic stiffness matrix of the multi-node,cable-truss elements was consistently derived. The steel wales pre-stressed externally in the IPS system were chosen as numerical examples and analyzed under various loading conditions. The cable tensions calculated using the present element were compared with the results of the flexibility method and those using the two-node truss element, respectively.

Determination of cable force based on the corrected numerical solution of cable vibration frequency equations

  • Dan, Danhui;Chen, Yanyang;Yan, Xingfei
    • Structural Engineering and Mechanics
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    • v.50 no.1
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    • pp.37-52
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    • 2014
  • The accurate determination of cable tension is important to the monitoring of the condition of a cable-stayed bridge. When applying a vibration-based formula to identify the tension of a real cable under sag, stiffness and boundary conditions, the resulting error must not be overlooked. In this work, by resolving the implicit frequency function of a real cable under the above conditions numerically, indirect methods of determining the cable force and a method to calculate the corresponding cable mode frequency are investigated. The error in the tension is studied by numerical simulation, and an empirical error correction formula is presented by fitting the relationship between the cable force error and cable parameters ${\lambda}^2$ and ${\xi}$. A case study on two real cables of the Shanghai Changjiang Bridge shows that employing the method proposed in this paper can increase the accuracy of the determined cable force and reduce the computing time relative to the time required for the finite element model.

Vibration control of a stay cable with a rotary electromagnetic inertial mass damper

  • Wang, Zhi Hao;Xu, Yan Wei;Gao, Hui;Chen, Zheng Qing;Xu, Kai;Zhao, Shun Bo
    • Smart Structures and Systems
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    • v.23 no.6
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    • pp.627-639
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    • 2019
  • Passive control may not provide enough damping for a stay cable since the control devices are often restricted to a low location level. In order to enhance control performance of conventional passive dampers, a new type of damper integrated with a rotary electromagnetic damper providing variable damping force and a flywheel serving as an inertial mass, called the rotary electromagnetic inertial mass damper (REIMD), is presented for suppressing the cable vibrations in this paper. The mechanical model of the REIMD is theoretically derived according to generation mechanisms of the damping force and the inertial force, and further validated by performance tests. General dynamic characteristics of an idealized taut cable with a REIMD installed close to the cable end are theoretically investigated, and parametric analysis are then conducted to investigate the effects of inertial mass and damping coefficient on vibration control performance. Finally, vibration control tests on a scaled cable model with a REIMD are performed to further verify mitigation performance through the first two modal additional damping ratios of the cable. Both the theoretical and experimental results show that control performance of the cable with the REIMD are much better than those of conventional passive viscous dampers, which mainly attributes to the increment of the damper displacement due to the inertial mass induced negative stiffness effects of the REIMD. Moreover, it is concluded that both inertial mass and damping coefficient of an optimum REIMD will decrease with the increase of the mode order of the cable, and oversize inertial mass may lead to negative effect on the control performance.