| As a critical component in the cable-stay bridges,the stay cable is prone to harmful vibrations induced by external excitation,which significantly affects the safety and integrity of the bridge.At present,the passive dampers are commonly employed for vibration mitigation of the stay cable.The inerter can generate a large equivalent inertial mass(inertance)through a small physical mass,thereby significantly improving its mass ratio and structural vibration mitigation performance.The electromagnetic damper is another structural damper,which can provide adjustable damping force by employing a specific circuit and owns energy harvesting performance.Combining the characteristics of inerter and the electromagnetic damper,two novel passive inerter-based dampers(namely,EIMD and TIED)are proposed in this dissertation,which have the dual-function of vibration control and energy harvesting.Considering a 135 m long stay cable,a series of studies regarding vibration mitigation and energy harvesting performance of the EIMD and TIED are conducted.Detailed research contents are presented as follows:(1)Firstly,full-scale vibration experiments of the cable based on the EIMD were performed,and the corresponding numerical model of the cable-EIMD system was established.According to the experimental and numerical results,the energy harvesting performances of the EIMD under free vibration and resonant vibration were systematically studied,and the effects of the EIMD parameters were discussed.The effect of the inertance was demonstrated positive for the energy harvesting performance of the EIMD.Based on theoretical research and numerical simulation,the consistency of the optimal parameters of the EIMD for vibration control and energy harvesting performance was verified.(2)Then,full-scale vibration experiments of the cable based on the TIED were performed,and the corresponding numerical model of the cable-TIED system was established.According to the experimental and numerical results,the vibration control performance of the TIED under free vibration was systematically studied,and the effects of the TIED parameters were discussed.Taking the damping ratio as the index,the optimal parameters of the TIED for vibration control of the stay cable were studied,including the inertance and the total damping coefficient.Through the experimental and numerical results,the frequency dependence of the TIED vibration damping performance was verified,and the effect of frequency ratio on its vibration damping performance was preliminarily studied.Finally,the effects of the damper position,the stiffness of the spring and the tension of the stay cable on the optimal parameters of the TIED and the corresponding damping ratio were studied.The research results demonstrate that the vibration mitigation performances of the proposed dampers are better than traditional linear viscous damper.For example,the measured modal damping ratio of the cable provided by TIED can be increased by 299.5% as compared to the linear viscous damper.In addition,the EIMD and the TIED also own potential energy harvesting performance,which is enough for powering a WSN or a semi-active damper.The research results of this dissertation can provide design reference for the application of EIMD and TIED in the vibration mitigation and energy harvesting of the stay cable. |
