To address potential vibrations in the balcony system of a new,  state-of-the-art, mid-size 2,150 capacity entertainment (music and event) venue, DEICON incorporated six tuned mass dampers (TMDs) into the 3-sided, 270-degree, wrap-around balcony, with bird’s eye view of the stage.
When audience in music venues and theaters move rhythmically to music or performances, the dynamic loads can cause the balconies to vibrate. These vibrations can lead to discomfort for the audience and, in extreme cases, structural damage. To mitigate these vibrations, without introducing architecturally unattractive features such as columns,  engineers often use tuned damping to reduce the vibrations, ensuring the comfort of the audience.
tuned mass dampers under the balcony

Figure 2 Two TMDs installed underneath the balcony

As expected, and shown by the model-predicted shapes of principal modes depicted in Figure 1, the areas of large vibration amplitudes (shown in red) are at the middle and close to the edges of the balcony system.   These modes were targeted by the TMDs.

Figure 1 Principal modes of the 3-sided balcony

Two tuned mass dampers (TMDs) per side of the balcony system, both tuned to the first natural frequency of their respective side, were integrated into the balcony.  Figure 2 shows one pair installed at its designated location. The blue traces in Figure 3 depict the power spectral densities (PSDs) and time traces of the measured acceleration at one  location close to the edge of the balcony, in response to a heel drop at the middle of the balcony near the edge, with the TMDs locked.  The red traces show the  measured data acquired in a similar fashion as that of blue traces except with the TMDs unlocked/operational. Comparison of red and blue traces attests to the effectiveness of the tuned mass dampers in adding damping to their target modes.
Without and with Tuned Mass Dampers

Figure 3 Power spectral densities and time traces of the measured vibration at the middle of the balcony near the edge, without and with the TMDs operational

The extent of added damping to the balcony is estimated by fitting an exponential decay (with known damping and frequency) to the envelope of narrow-band filtered time traces measured at the center edge of the balcony; see Figure 3.  As  noted on Figure 3, the damping ratio of the balcony without the TMDs operational is estimated at 1.7% and with the TMDs operational is estimated at 7.5%.  That is, the TMDs have increased the damping ratio of the balcony by nearly 4.5 folds (450%).