Seismic Response and Vibration Transmission Characteristics of Laminated Rubber Bearings with Single Disorder

AbstractThe characteristic receptance method of analyzing the free wave propagation of a finite monocoupled periodic system with a single disorder is applied to study the vibration transmission through the periodic bearing, due to horizontal ground motion, into which the shear modulus or thickness disorder of a rubber layer has been introduced. The upper building and laminated rubber isolator are respectively modeled as two different types of periodic systems. The superstructure model is formulated according to the Euler-Bernoulli beam theory for the walls, while the floors are considered as lumped masses. The shear beam theory along with the lumped-mass model is used to describe the bearing with the rubber layers, reinforced by periodically placing vulcanized steel shims. The point impedance of the superstructure obtained from the indirect receptance and propagation constant is utilized in the development of the displacement transmissibility function of the bearing. The study of the seismic response and dynamic transmission characteristics of the bearings shows that a small shear modulus or large thickness in the disordered element generally enhances the isolated capability. The presented analysis indicates how disorders can be used most effectively for vibration isolation in existing laminated rubber bearings or the design of new laminated rubber bearings.