rubber Damper

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elastomer damper

book of damper

Structural Rubber Dampers
In the conventional approach to earthquake design of building structures, the earthquake is resisted by a combination of strength, ductility(deformibility), and inelastic energy dissipation. Generally, the inherent damping for these structures is low (about 1% to 5% of critical damping), thus the energy dissipation in the elastic deformation is very small. However the inelastic energy dissipation requires inelastic deformation over several cycles and this invariably not only damages the structure but also increases flexibility of the structure, and often results in significant permanent lateral displacement of the building. By incorporating structural rubber dampers into buildings through braces earthquake damage in buildings can be prevented. The dampers dissipate the earthquake energy and minimize any damaging deformation to the structure. In the last 30 years rubber dampers have been extensively used in wind vibration control applications. The first, and most notable of these, was in the infamous twin towers of World Trade Center in New York City, where 100 dampers were installed on each floor. The other notable rubber damper applications are for 73-story Columbia Sea First Building and the 60-story Number Two Union Square Building, both in Seattle, USA. These rubber dampers have proved to offer a good solution to the problem of wind-induced vibrations in tall buildings. However, for seismic application, the damping required for the dampers are considerably greater than those necessary to be effective for wind vibration control. The greater severity of the earthquake loading imposes significantly larger deformations on the dampers requiring a very high damping compound to control the deformation. Towards this end, MRB has developed a high damping natural rubber compound with a loss factor of 0.4. Despite the high damping, the compound still retain its excellent mechanical properties such as strength, fatigue and resilience.