Tuned Liquid Column Gas Damper in Structural Control - Design Optimization of Active and Passive Structural Control Systems - page 164

Figure 3. a) Modal displacements of first three modes of vibration with modal centers of velocity b)
Weighed sum of amplitude response functions (generalized coordinates) of the thirty storey, moderately
asymmetric building with linearized TLCGD attached, α = 0 . (Adapted from Fu et al. (2010)).

new type of base isolation element provides high
vertical and low lateral stiffness and virtually
no damping. Bachman (2010) developed a base
isolation system separated into two parts: the
classical reinforced rubber element together with
separately arranged sliding elements operating in
dry friction. In order to resist (minor) wind gusts
and small seismic disturbances (e.g. also of traf-
fic origin) without base isolation motion, these
elements must supply sufficient static friction.
During an earthquake or strong wind incident the
entire vibration energy is permanently dissipated
by the sliding elements in dry friction which are
thus suffering from wear. Khalid et al. (2010)
avoided such abrasive processes and adapted the
concept of a functionally separated modular base
isolation system by providing the required energy
dissipation for excessive horizontal vibrations of
the isolation modes by TLCGD installed in the
basement. Experimental verification is given in
Khalid et al. (2009) and the new isolation system is
partly presented in Ziegler et al. (2011). It consists
of three main elements, developed in full detail in

Kahlid (2010): the novel pendulum spring base
isolation element, an innovative sliding element
to resist minor dynamic loads and a TLCGD to
dissipate vibrational energy during the strong
motion phase of an earthquake.
The novel pendulum-spring base isolation
element consists of a pivoted upright-pendulum
encapsulated by a coil steel spring acting in shear,
see Figure 4a for the element designed for a
typical residential house (more building details
are presented in the following numerical study).
The maximum vertical stiffness is about 13-times
the horizontal stiffness allowing for a base iso-
lated natural frequency of about 0.5 Hz , thereby
forming a suitable low pass filter. Only some
fraction of the vertical dead weight load of the
building is supported by the steel springs, the
remaining part is carried by the (stainless) steel
columns of length l with spherical ends pivoted
between spherical bearing cups. A horizontal
displacement of the pendulum δ

h = sin with
a tilt angle limited to about ϕ ≤ °

ϕ

15 , causes a