Tuned Mass Dampers

Wide span structures (bridges, spectator stands, large stairs, stadium roofs) as well as slender tall structures (chimneys, high rises) tend to be easily excited to high vibration amplitudes in one of their basic mode shapes, for example by wind or marching and jumping people. Low natural frequencies are typical for this type of structures, due to their dimensions, as is their low damping. With GERB Tuned Mass Dampers (TMD), these vibrations can be reduced very effectively.

The TMD may consist of:

  • Spring

  • Oscillating Mass

  • Viscodamper®

as main components, or may be designed as a pendulum, also in combination with a Viscodamper®.

Each TMD is tuned exactly to the structure and a certain natural frequency of it. Such TMD have been designed and built with an oscillating mass of 40 to 10.000 kg (90 to 22.000 lbs) and natural frequencies from 0.3 to 30 Hz. Vertical TMD are typically a combination of coil springs and Viscodampers®, while in case of horizontal and torsional excitation in the corresponding horizontal TMD the coil springs are replaced by leaf springs or pendulum suspensions.

Fig. Amplitude - Frequency response of a low damped system without (blue) and with (yellow) tuned mass damper

Tuned mass dampers are mainly used in the following applications:

  • tall and slender free-standing structures (bridges, pylons of bridges, chimneys, TV towers) which tend to be excited dangerously in one of their mode shapes by wind,

  • stairs, spectator stands, pedestrian bridges excited by marching or jumping people. These vibrations are usually not dangerous for the structure itself, but may become very unpleasant for the people,

  • steel structures like factory floors excited in one of their natural frequencies by machines , such as screens, centrifuges, fans etc.,

  • ships exited in one of their natural frequencies by the main engines or even by ship motion.

TMD may be already part of the structure’s original design or may be designed and installed later.

Tell us your vibration problem and we shall give you our proposals for its solution.