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

Yuanfeng Duan, Yi Qing Ni, Hongmei Zhang, Billie F. Spencer, Jan Ming Ko, Shenghao Dong

Research output: Journal article publicationJournal articleAcademic researchpeer-review

23 Citations (Scopus)


In this paper, a method for analyzing the damping performance of stay cables incorporating magnetorheological (MR) dampers in the passive control mode is developed taking into account the cable sag and inclination, the damper coefficient, stiffness and mass, and the stiffness of damper support. Both numerical and asymptotic solutions are obtained from complex modal analysis. With the asymptotic solution, analytical formulas that evaluate the equivalent damping ratio of the sagged cable-damper system in consideration of all the above parameters are derived. The main thrust of the present study is to develop an general design formula and a universal curve for the optimal design of MR dampers for adjustable passive control of sagged cables. Two sag-affecting coefficients are derived to reflect the effects of cable sag on the maximum attainable damping ratio and the optimal damper coefficient. For the cable configurations commonly used in cable-stayed bridges, the sag-affecting coefficients are directly expressed in terms of the sag-extensibility parameter to facilitate the control design. A case study on adjustable passive vibration control of the longest cable (536 m) on Stonecutters Bridge is carried out to demonstrate the influence of the sag for the damper design, and to figure out the necessity of adjustability of damper coefficients for achieving maximum damping ratio for different vibration modes.

Original languageEnglish
Pages (from-to)537-551
Number of pages15
JournalSmart Structures and Systems
Issue number6
Publication statusPublished - 1 Jan 2019


  • MR damper
  • Open-loop control
  • Passive control
  • Sagged cable
  • Vibration mitigation

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Computer Science Applications
  • Electrical and Electronic Engineering


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