Incremental Dynamic Analysis Results

Damage to structures caused by earthquakes results in direct and indirect losses
that inhibit a community’s ability to recover. The installation of passive
control devices is one means to mitigate damage. A variety of passive control
devices exist. Inerter-based devices have received attention for their ability
to provide large-added mass effects, while having a relatively small physical
mass. This is typically achieved with a mechanism that converts translational
motion to the rotation of a flywheel. In a clutch inerter, the conversion occurs
in a one-way fashion such that energy transferred to the flywheel cannot
transfer back from the device to the structure it is attached to. Such behavior
could be particularly advantageous in mitigating the effects of near-field
earthquakes. However, few studies have considered the seismic performance of
structures with clutch inerters. As a result, the effect of the device
parameters (i.e., effective mass and damping), the ability of the device to
delay the yielding of the structure, and the relative effectiveness of the
device in far-field and near-field earthquakes, which more often include a
dominant pulse, are uncertain. This paper addresses these gaps in knowledge
through a numerical study of a SDOF structure with a clutch inerter. This
system, which is modeled in the OpenSees framework, considers the nonlinear
behavior of the structure itself that would result from yielding in the
structural system in addition to the nonlinear behavior of the clutch inerter.
Incremental dynamic analyses were performed with suites of recorded earthquake
ground motions. The results of these analyses showed that the clutch inerter is
typically significantly more effective than a comparable viscous damper. It was
also found that the performance of the clutch inerter was more sensitive to
damping when subjected to far-field excitations. The results of this study show
that the clutch inerter has great potential as a passive control device for
delaying the onset of yielding and otherwise mitigating the effects of a wide
range of types of seismic excitations.