Geology Reference
In-Depth Information
CONCLUSION
Therefore the TLCGD is split into several smaller
units acting in parallel keeping the length of
the fluid column constant. The recommended
subsequent fine tuning in state space renders the
optimal frequencies slightly modified and more
robust when compared to traditional Den Hartog
tuning. Since the modal equations of motion are
identical to those given for the asymmetric build-
ing, however without rotation of the frame, the
reduction of the dynamic magnification factor only
depends on the mass ratio. A possible installation
in the selected vertical section of a double curved
dam is sketched in Figure 9. By changing the gas
pressure, thus adapting the static pressure head, it
is even possible to adjust the TLCGD to modified
dynamic parameter e.g. to adapt it to the natural
frequency changing with the water level in the
reservoir. However, the optimal position might
become sub-optimal with changing modal shapes.
Tuned liquid column gas dampers show excel-
lent vibration and energy absorbing capabilities
appropriate for many applications in earthquake
engineering. It has been shown that the vibration
reduction is equal to well established dynamic
absorber e.g. the TMD of spring-mass-dashpot
type, if the vibration is dominantly horizontal,
which occurs e.g., either if the main system is a
moderately asymmetric space frame or if the main
system is a bridge with critical lateral flexural-
torsional natural modes, as made evident in this
paper. However, its salient features make the
TLCD superior to commonly applied alternative
systems: they neither have moving parts nor ele-
ments which suffer from friction, wear and tear.
One of the most important developments was
the recently established TLCGD-TMD analogy
facilitating a simple design and tuning process for
almost all civil engineering structures.
Figure 9. a) Vertical section of a double curved dam with symmetric TLCGD b) detailed schematic view
of TLCGD smoothly integrated below the dam crest. Closed pressurized pipe sections have equal volume.
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