7.2.3. Building with a TMD – both excitation components –
second variant
Fig. 15 presents the curves describing the horizontal vibration
of the highest storey (25 floor) of the building model with a
TMD installed. The kinematic excitations were modeled by both
components of the ground motion working simultaneously:
– horizontal – modified Sierra Madre California seismogram,
– vertical-zzðtÞ ¼ 0:0005 sin ð2π0:7tÞ þ 0:0005 sinð2π1:91tÞþþ0:001
sinð2π1:92t þ 90Þ where the value 1.92 Hz corresponds to the
frequency exciting the main parametric resonance in the
pendulum.
Fig. 15 shows comparison of the vibration of a numerical
model with a TMD in the case of excitations:
– only caused by the horizontal component of ground
motion (red color),
– caused by both vertical and horizontal components simultaneously
(black color).
This time the detrimental effect of the vertical component
of the ground motion on the pendulum's functioning takes
place in the second part of the excitation's duration. This is
due to the change in the vertical excitation amplitude, which
rises in time and becomes unstable around the 30th second.
This, of course, is the direct reason for the 70% rise in the
building's transversal vibration.
In terms of the convergence of the numerical and experimental
results (see [51]), it is again clear that the trend line and
the estimated extreme values of the amplitudes remain the
same, while the character of the history in time itself differs
slightly