Dancing, as in other rhythmic activities, subjects the floor to repetitive loadings. The frequency of dancing load depends on the tempo of the music (normally between 1.5-3.5 Hz and even as high as 4 Hz). Depending on the type of dance, the dancers are either always in contact with the floor or the they are jumping in which the contact with the floor is not maintained. In the first type, the floor is subject to the dancing load at the fundamental (dancing) frequency and a very few of higher order harmonics (multiples of dancing frequency). The second type of dancing load is potentially more severe than the first type; this is mainly because in addition to the fundamental (dancing frequency) the floor is subject to many of its higher order harmonics. These high order harmonics can potentially resonate even the rather stiff floor systems with higher natural frequencies.
Following the measurement of vibration and finite element analyses of the floor system, five bays of a dance floor were identified as having objectionable floor vibration. As the outcome of the measurement and analyses, the natural frequencies and the shapes of the first vibration mode of these bays were identified. Subsequently, ten tuned mass dampers (TMDs) with the active mass sizes of 700 and 750 Kg were designed and built to mitigate the tonal vibration of these bays. Two TMDs were installed underneath each of the 5 target bays. Three sets of coils springs in conjunction with the above-mentioned active mass sizes were used for individually tuning the TMDs to the natural frequencies of the first vibration mode of the bays they were designed for.
Following the installation of the TMDs, floor vibration at the 5 target bays, without and with the tuned mass dampers operational, were measured. Comparison of the measured floor vibration without and with the TMDs clearly showed the effectiveness of the TMDs in adding a substantial amount of damping to the first mode of vibration of their corresponding bays. The tuned mass dampers successfully dampened their target modes, quieting the vibration of the floor system.