Wind-induced vibration control of a constructing bridge tower with MRE variable stiffness tuned mass damper

With the rapidly increasing number of long span bridges being built all over the world, the wind-induced vibrations of their constructing high bridge towers are becoming a serious issue. These vibrations will discomfort workers, affect construction accuracy, lead to construction period delay, and sometimes even cause accidents. Tuned mass dampers (TMDs) are well accepted to have a good performance in wind-induced vibration control under the condition that their natural frequencies are tuned to the natural frequencies of the main structures. However, as the natural frequencies of the bridge towers keep varying during its construction, their wind-induced vibrations can hardly be controlled by conventional TMDs. To improve the control efficiency, a novel magnetorheological elastomer variable stiffness tuned mass damper (MRE VSTMD) was proposed to retune the system. To verify the efficiency of the proposed system, a constructing bridge tower was modeled analytically and the corresponding MRE VSTMD was designed. Simulations were carried out and evaluations were made among the uncontrolled, passive controlled and semi-active controlled structures. It is proved that the proposed MRE VSTMD can improve the performance of passive TMDs by up to 40%. It is also observed that the softening behavior can double the stiffness variable range of MRE layers, indicating MRE VSTMD's potential to further improve its performance with time varying excitation powers.