Reducing Resonant Vibrations of Adjacent Base Isolation Systems Using Connected Control Method

The connected control method (CCM) is a vibration control strategy that uses damping devices between adjacent dynamic systems to impart dissipative forces upon one another for mitigating their fundamental resonant vibrations. CCM was originally conceived for civil applications to mitigate the resonant vibrations of adjacent high-rise buildings from seismic and wind excitations. This paper examines CCM as a potential vibration control strategy for mechanical applications, particularly for the case of adjacent base isolation systems. These systems typically have lightly damped fundamental resonant frequencies to provide effective isolation at the higher frequencies. The conventional approach to reduce the vibrations of these fundamental resonances is to add damping to the isolators, but at the expense of degraded isolation. For cases when the two or more base isolation systems are adjacent to each other, it is possible to apply CCM to mitigate their fundamental resonant vibrations by interconnecting them with damping devices. This paper first reviews the basic theory of CCM for adjacent one degree of freedom (DOF) mass-spring systems connected by a viscous damper, followed by analytical modeling and optimization of adjacent 6-DOF mass-spring systems connected by viscous dampers. In addition, experimental results using simplified base isolation systems connected by Taylor Devices viscous dampers are also presented to demonstrate the effectiveness of CCM. Results show that CCM can effectively reduce the resonant vibrations of adjacent base isolation systems without degrading the isolation effectiveness as long as their fundamental resonances are sufficiently separated.