Vibrations are a significant challenge to the design of buildings and towers. They occur for many reasons ranging from footsteps to earthquakes. Vibrations lead to discomfort, material fatigue and structural damage. In extreme cases, vibrations may cause a structure to collapse. Modern structures are lightweight and built from low-damping materials such as steel, so vibration problems are increasingly common.
Reducing vibration levels can be difficult. In many cases, the simplest and most cost-effective solution is the installation of a Vibration Damper, often called a Tuned Mass Damper (TMD). A Vibration Damper is a simple, robust mechanical device that absorbs mechanical energy from a vibrating structure and then converts this energy into heat.
The TG vibration dampers presented below extend the principles of the TMD for flexible damping of vertical vibrations and for very tall towers.
TG Broadband Damper
Traditional Vibration Dampers need to be precisely tuned to a specific structure. So traditional Vibration Dampers are typically custom-made, leading to significant costs, which can be several times higher than the material cost for the actual Vibration Damper.
We have developed a new type of Vibration Damper, the TG Broadband Damper, which is simpler to use than a traditional TMD. The TG Broadband Damper is extremely robust and flexible. It delivers high damping performance on all structures within a range of eigenfrequencies and modal masses. For typical structure parameters, a material cost reduction of 50% can be achieved compared to a traditional TMD.
Our design of the TG Broadband Damper for up-down vibrations provides a compact damper unit effective against vibrations of floors, balconies, stairways and bridges.
The damper design is modular and ready for quick manufacture and deployment, with several damper units currently installed against floor vibrations in Norway. New dampers can be based on either customer specifications or our own extensive measurement and analysis capability. Contact us for a quote.
The TG Compact Low Frequency Damper for very tall towers
Very tall towers are subject to low-frequency vibrations in both horizontal directions. Traditional pendulum dampers can be used against these, but at low tower frequencies (tall towers), the pendulum wires must be exceedingly long.
We have developed the TG Compact Low Frequency Damper (patent pending), which delivers frequencies down to 0.10Hz or even lower, within a compact container of a total height of 6.0m. The TG Compact Low Frequency Damper can be applied to buildings, stacks and wind turbine towers.
We are currently working on an industrial demonstration of the TG Compact Low Frequency Damper. Contact us if you have questions.
Effective mass of Tuned Mass Dampers
Many widely used types of damper involve off-axis motions. This introduces so-called added mass. The effects of added mass are far from intuitive and must be understood, when a damper is designed. Because the optimal performance as well as the optimal tuning are significantly altered!
We have worked extensively on this problem, and contributed original research to the litterature, see [Effective mass of tuned mass dampers, Tophøj, Grathwol et al.]. And we are ready to help you.