7.2.2. Building with a TMD – both components of excitation – first variant Fig. 14 presents the curves describing the horizontal vibration of the highest storey (25th floor) of the building model with a TMD installed and attuned to the first eigenfrequency of the building model. The kinematic excitations were modeled by both components of the ground motion working simultaneously: – horizontal – modified Sierra Madre California seismogram, – vertical – zzðtÞ ¼ 0:0024 sinð2π1:92tÞ, where the value 1.92 Hz corresponds to the frequency exciting the main parametric resonance in the pendulum. The detrimental effect of the vertical component of the ground motion is especially visible in the initial and final stages of the time of the horizontal excitation's duration. In those stages, the displacement of the highest storey of the building is greater than in cases where the vertical component has been omitted (red color in Fig. 14). The rise in the amplitudes of the building's transversal vibration is at an average 70%. In cases where the excitation lasts longer, it would be possible to observe the exponential growth of the vibration amplitudes that is characteristic of parametric resonance