关键词: 桥梁工程；拉索减振；复模态分析；新型惯质阻尼器；减振效果；广谱减振；实桥阻尼器应用

Abstract: A new type of inertial damper for cable was proposed, which was composed of gear rack, inertial element and viscous damping element. The dampers theoretical design method was given, and its energy dissipation mechanism was pointed out. The cable-inertial damper systems in-plane motion equation was established. Using the complex modal analysis method, the single-order vibration reduction performance analysis and multi-order broad-spectrum vibration reduction performance analysis of cable-inertial damper system was carried out. The results show that the inertial damper has a good damping effect on the cables single-order vibration, with the first-order vibrations modal damping up to 6.14, the second-order vibrations modal damping up to 5.17 and the third-order modal damping up to 3.66. The single-order damping capacity of the inertial damper is one order of magnitude higher than the ordinary viscous damper. In terms of broad-spectrum vibration reduction, such as considering the first four vibration modes, when the mass ratio μ is at 0.1 and 0.2, the vibration reduction effect of inertia damper is greatly improved compared with that of ordinary viscous damper. When the damper is installed at 3% cable length, the first four order broad-spectrum vibration reduction effect increases by 14.6%. However, attention should also be paid to the “embedding effect” of inertial damper on high-order vibration modes. When the mass ratio μ is at 0.5 and 0.8, the inertial damper has a suppression effect on the higher-order modal damping. In this case, the first eight order of broad-spectrum vibration reduction design cannot be carried out. According to the analysis in this study, after multi-parameter tuning such as the inertial, viscous damping coefficient and installation position, a corresponding inertial damper is designed for the cable in a practical project and its broad-spectrum characteristics are also better than those of the ordinary viscous dampers, which verifies the feasibility of the application in real bridge.

Key words: bridge engineering; cable damping; complex mode analysis; new inertial damper; damping effect; broad-spectrum damping; the real bridge damper application