Summary This study proposed a system consisting of a stay cable transversely attached with a pre‐tensioned shape memory alloy (SMA) wire. Cyclic tension loading test of pre‐tensioned 0.5‐mm‐diameter NiTi wire was conducted first. The effective modulus and energy dissipation per unit volume were obtained from the tested hysteretic loops of the pre‐tensioned SMA wire. The effects of prestrain on the energy dissipation and effective modulus of the SMA wire was discussed. Preliminary fatigue testing of 0.5‐mm‐ and 1.0‐mm‐diameter SMA wires was carried out, and a vibration mitigation experiment with a model stay cable transversely attached with a pre‐tensioned SMA wire was then conducted. Both the first and the second in‐plane mode vibrations were tested. The effects of the SMA wire installation location and pre‐tension level on the frequency and damping ratio of the model‐cable‐SMA‐wire system were discussed. The test results confirmed there was an optimal pre‐tension level of the SMA wire for maximum mode damping, and in this test, the maximum damping ratio was larger than 0.50%. A preliminary linearized theoretical study was also carried out to further explore the dynamics of the model‐cable‐SMA‐wire system. The comparison results showed good agreement of theoretical frequency and damping to the tested version. The study confirmed the potential application of pre‐tensioned SMA wires as cross‐ties for stay cable vibration mitigation.

Summary Connecting cables together to form a cable net could mitigate cable vibration. However, because most of the studies and practices use secondary cables as cross‐ties, little attention has been paid on the connection by dampers. In this paper, a system of two parallel taut cables with an interconnected damper is proposed to mitigate cable vibration. The characteristic equation of the system is derived by applying the transfer matrix method. The analytical special limit solutions, which are corresponding to special kinds of vibration mode, are given for the case when the parameter of the system tends to specific limiting values. Analytical solutions to twin taut cable system, two taut cables with different mass–tension ratios, whereas other cable parameters are the same were also discussed. Parameter studies were further addressed to study effects of cable length ratio and frequency ratio on the third and fourth mode behaviors for two cables system. Different solution regimes with different kinds of modes are discussed as damper interconnected at arbitrary point of cables. Multimode damping optimization method was proposed with the concept of maximizing the average of damping ratio while minimizing the variation for the considered multimodes. The case study for two length cables of a harp system was carried out. It was found that connecting two cables with a properly designed damper could significantly increase multimode damping ratio while slightly increase vibration frequency.

<p>This study proposed and tested a system of a stay cable transversely attached with a tensioned Shape Memory Alloy (SMA) wire. Cyclic tension loading test of pre-tensioned 0.5mm diameter SMA wire was firstly conducted. The effective modulus and energy dissipation per unit volume were derived from the tested hysteretic loops of pre-tensioned SMA wire. The pre-strain effects on the effective modulus and energy dissipation of SMA wire was discussed based on the test results. Then vibration mitigation experiment of a model stay cable transversely attached with a tensioned SMA wire was conducted. The strain level of SMA wire was calculated from the stay cable force increment. Both the 1st and the 2nd in-plane vibration mode were tested in the experiment. The effects of the SMA wire installation location and pre-strain on frequency and damping ratio of the model-cable-SMA-wire system were discussed. The test results confirmed there was an optimal pre-strain of SMA wire for the maximum mode damping larger than 0.50%. The study confirmed great potential application of pre-strained SMA wire as cross-ties for stay cable vibration mitigation.</p>