Tuned Mass Dampers
Wide span structures such as bridges, stairs, and roofs, as well as tall, narrow structures such as chimneys, antennas, masts and buildings, can be easily excited to high vibration amplitudes in their first or higher eigenforms. These excitations can be caused by wind forces, pedestrian traffic, machinery or earthquakes and they can have a large effect on these structures, that have an inherently low natural frequency and minimal damping.
TVS Acoustics utilize GERB tuned mass dampers (TMD’s) to easily and cost effectively reduce these effects.
There are generally three types of applications that often require the use of tuned mass dampers:
- Tall, free-standing structures such as chimneys, antennas, skyscrapers, TV towers, large bridges and pylons, that all could be excited by wind forces
- Smaller bridges that could be excited by vehicle or foot traffic like what happened with the Millennium Bridge in London
- Structures and floors that may be subject to machine induced vibration. This is becoming more of an issue with more and more lightweight, large span floors supporting activities such as fitness gyms where the rhythmic running of people on banks of treadmills can cause big problems
The tuned mass dampers can be part of the original design of a structure, or may be retrofitted at a later date once a problem becomes apparent. Simple in design, ruggedly built and maintenance free, these TMDs provide highly effective in reducing the amplitude of vibration, whilst offering a low cost and space saving alternative to having to stiffen a structure with additional steels/columns.
All GERB TMDs, both vertical or horizontal, have three main components:
- A coiled spring, leaf spring or pendulum
- An oscillating mass
- A Viscodamper® (viscous fluid damper)
Every TMD is exactly tuned to the main natural frequency of the structure. GERB TMD’s have been installed successfully Worldwide with oscillating masses from 20kg to 10,000kg, and vibration frequencies from 40Hz down to as low as 0.3Hz.
TVS and GERB are able to offer:
- Dynamic analysis of the structure
- On site vibration measurement and assessment of bridges, buildings, machinery and other equipment
- Design of tuned mass dampers, tuned to the main structure
- Fabrication and testing of tuned mass dampers
- Installation and fine tuning of tuned mass dampers, along with final measurement and assessment
Although the theory behind TMDs have been well known for a long time, it is still difficult to provide exact tuning and predefined system damping. Furthermore, the three components must not change their dynamic properties over time, even when exposed to variable weather conditions.
As such it is critical that a manufacturer such as GERB, with decades of experience in the design, fabrication and installation of tuned mass dampers, is selected to assist with these projects.