Design Approach and Practical Formulas of Electromagnetic Inertial Mass Dampers for Cable Multimode Control
Wenai Shen, Jianyu Hao, Hongping Zhu
Abstract
An inerter-based damper termed electromagnetic inertial mass damper (EIMD) has been demonstrated as a high-performance passive damper for bridge stay cables. However, how to design an EIMD for suppressing cable multimode vibration remains largely unsolved. Here, we present practical design formulas of the EIMD for cable multimode control. A Q-point method is presented for EIMD design aiming at cable multimode control. Then, we propose asymptotic solutions of the optimal parameters of the EIMD for maximizing the damping ratio of the Q point, which guarantees that the modal damping ratios within the mode range considered are no less than that of the Q point. The accuracy of the practical design formulas is verified via both numerical study and full-scale test data. In addition, two design examples of real cables in China, including a 634-m-long cable, are presented. Comparisons of the results illustrate that the modal damping ratios offered by the EIMD outperform the counterparts of viscous dampers. This study provides practical design formulas for an EIMD or other similar dampers for cable multimode control.