A STUDY ON THE INTERACTION BETWEEN THE PRIMARY AND SECONDARY STRUCTURES OF COMBINED STRUCTURES

A study on the transfer functions of primary structures and the relative power flow between primary and secondary structures under evolutionary earthquake input gives a physical insight into the interaction between the primary and secondary structures of combined structures. The interaction between primary and secondary structures depends mainly on the mass ratio, stiffness ratio, coupling stiffness and frequency tuning between the primary and secondary structures. The interaction also depends on the location at which the secondary structures are attached to the primary system. The analysis shows that the secondary systems, instead of being vibration absorbers, have a significant driving effect on the primary structure when the mass ratio of the secondary to the primary system is very large. An asynchronous driving principle is proposed to reduce the driving effect.