Control of Wind-Induced Coupled Vibration of Long-span Bridges with Tuned Mass Dampers

摘要

Much research effort has been undertaken in mitigating excessive vibrations and improving aerodynamic stabilities for bridges during construction and at service. Among all the control procedures, dynamic energy absorbers such as tuned mass dampers (TMDs) provide a supplemental modal damping to the mode of concern. Previous studies have found that supplemental damping provided through appropriate external dampers could certainly increase the flutter stability and reduce the buffeting response of long-span bridges. For a single-mode vibration control, an equivalent damping ratio was often adopted to assess the control efficiency and performance. With the increase of bridge span lengths and the tendency of bridge cross-section being more slender and streamlined, the vibration modes of bridges are more prone to couple together due to the interaction between the bridge and strong wind. As a result, the control performance of TMDs designed for the conventional single-mode vibration may deteriorate greatly in high wind velocity. The present study investigated a new control approach that allows TMD system to be more efficient on the coupled vibration control under high wind velocity. The new control design of the TMD system considers not only resonant vibration, but also the vibration due to modal coupling effects. For such purpose, a theoretical derivation of the closed-form solution of coupled buffeting for a bridge-TMD system was made. A prototype bridge was investigated in order to explain and validate the proposed strategy.