ANALYSIS, DESIGN AND APPLICATIONS OF ROTATIONAL FRICTION DAMPERS FOR SEISMIC PROTECTION

The paper introduces the basic types of damping devices and summarizes the benefits
of implementing supplemental damping systems for seismic protection
of buildings and other structures. A novel damper device based on the rotational
friction hinge concept invented by the first author is described. The slip capacity
of the device and its energy dissipation capacity can be easily increased by adding
more layers of steel plates and friction pads. The experimental evaluation of the
original damper unit was first carried out in DTU, Denmark under displacement
and forcing frequency control. The friction pads were made from advanced material
capable of sustaining up to 400 cycles without property degradation. In 2001,
an international team including the authors conducted intensive research program
on a three-storey building equipped with rotational friction dampers at the largescale
shake-table testing facility of the NCREE, Taiwan. The performance
of the damped structure was examined for 14 cases of seismic input with peak
ground acceleration (PGA) varying from 0.05g to 0.30g. The testing demonstrated
the remarkable efficiency of the damping system for reducing the lateral displacements
and interstorey drifts of the test building. Nonlinear time-history
analyses were used for predicting the dynamic response of the structure and selecting
adequate damper capacities. A few representative applications of RFDs
for seismic protection of buildings and facilities in Europe and Japan are given
which demonstrate the reliability of the devices and their most typical arrangements
within new and existing structures. It is concluded that the displacementdependent
dampers such as friction and metallic are a powerful and nonexpensive
engineering tool for solving vibrational problems both in new and existing
structures.

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