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CONCLUSIONS
In the previous sections, we have provided an overview of some computational mechanics studies of
seismic protective devices. Both metallic dampers and viscoelastic dampers are considered.
For the metallic dampers, a two-surface cyclic plasticity model is developed that has the capability to
reproduce stabilized hysteresis loops under constant amplitude cycling, while retaining an inherent
self-consistency under more general loading paths. Model parameters are established from
experimental data on structural steel that is independent of the damper response tests. For both the E-
damper and the triangular plate damper, the subsequent finite element analysis captures the main
features of the experimental damper results, while providing additional insight into the behavior. In
the case of the triangular plate damper, for example, the analysis identifies the important role of large
deformation effects and potential locking. The analysis also indicates that the triangular shape may not
be ideal for response under severe lateral deformations.
Meanwhile, the viscoelastic dampers are modeled as a thermorheologically simple generalized
Maxwell material. This provides a reasonable representation of both the frequency and temperature
dependence, while retaining computational efficiency. The finite element analysis captures the overall
damper behavior, including thermal softening. The continuum model also provides detailed
information that could be used to better understand damper durability, particularly in terms of
interfacial debonding.
In ail three cases, the computational continuum mechanics approach provides additional insight into
the behavior of the control device. This complements the results of physical experiments and the
initial back-of-the-envelope calculations that are more routinely performed. During a significant
earthquake, the performance of the entire structural system will often ultimately depend upon the
reliability of these critical control devices. Consequently, we recommend detailed computational
continuum mechanics evaluations of all seismic protective devices.
ACKNOWLEDGEMENT
Support for the work described in this paper was provided in part by the Multidisciplinary Center for
Earthquake Engineering Research under a cooperative agreement from the U.S. National Science
Foundation (Grant EEC-9701471). The authors gratefully acknowledge this support.
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