modal energy transfer in large structural systems using recurrent switching technique

Improving damping characteristics of large structural systems is usually based on using a massive number of energy dissipater devices (soong, 1990). however, in case of providing higher relative movement among different parts of a structural system, reduction in the number of such devices in the structural systems is conceivable. mass isolation technique is a seismic design approach in which a high damped structural system in consisted of a structure divided intotwo subsystems connected together with a few number of energy dissipaters (ziyaeifar, 2002; ziyaeifar et al., 2012). moreover, since in this approach damping devices are located in between two massive subsystems, there is a possibility of reducing reaction forces of dashpots using recurrent switching techniques that deploys inertial forces to provide balance for the system. in this work it is decided to improve the efficiency of recurrent switching technique by adapting the dashpot switching frequency with that of the natural frequencies of higher modes of the system. in this case it would be possible to dissipatea part of earthquake input energy in the modes that are not considered effectual in critical responses of the structural system.