Vibration Control Using Frictional Tuned Mass Dampers with Stick-Slip Motion

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Conference Proceeding

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Tuned mass dampers (TMDs) are proven to be effective in reducing both the acceleration and displacement responses of civil structures subjected to earthquake. The basic idea behind the use of a TMD in civil structures is to create an alternative path for the flow of mechanical energy in the dynamic system of primary structure to deviate the input seismic (or wind) energy from entering its key structural components such as beams and columns. This is achieved by storing and dissipating the input seismic energy in the TMD itself as it oscillates with the vibration of primary structure. The process of energy dissipation in the TMD can be carried out using solid friction by allowing the mass of TMD to slide over a surface attached to the primary structure rather than using viscous damping that is usually provided by viscous fluid dampers connecting the mass of TMD to the primary structure. The former method is relatively simpler to implement and it has a lower cost of installation, operation, and maintenance as well. A TMD that uses friction for energy dissipation is termed as frictional TMD (FTMD). Although the energy dissipation mechanism of FTMD is simple and cost-effective, it is susceptible to stick-slip motion, a highly nonlinear phenomenon occurring at low velocities when the dynamic state of moving mass abruptly shifts from the sliding phase to the sticking phase or vice versa. In particular, during the sticking phase when the mass of FTMD sticks to the friction surface, the FTMD can neither store nor dissipate the input seismic energy. The objective of this chapter is to study how stick-slip motion can affect the energy dissipation capability a FTMD and the seismic performance of primary structure. For this purpose, a 3DOF dynamic model is employed to model the interaction of FTMD with the primary structure (two-story base-isolated building) during the stick-slip motion. The friction force is described by a modified version of the Karnopp friction model in which a sticking velocity is defined to characterize the boundary between the sticking and sliding phases and perform a parametric nonlinear time-history analysis of 3DOF dynamic model. The numerical results show that for a given ground motion acceleration it is feasible to adjust both the mass of FTMD and the normal force in such a way that the intensity of ground motion remains above the breakaway level to avoid sticking, allowing the FTMD to slides continuously during the earthquake.


© 2024 The Society for Experimental Mechanics, Inc.

Publication Title

Dynamics of Civil Structures, Volume 2