The challenge of every engineer is to design structures as light as possible. Light and cost saving structures however are more influenced by natural forces like wind or waves . The forces caused by these elements can result in unwanted movements and damages from fatigue. In some cases designers are not familiar with the effects of vortex shedding and movements caused by wind or waves. The solution for these problems and to avoid damage to the structure is a Tuned Mass damper system.
Wind vibrations (Vortex Shedding)
The vibrations of slender structures are caused by cross-wind loads known as the phenomenon vortex shedding. Specific critical wind speeds around an object can create under and over pressures that makes it move (vibrate) in cross-wind direction. These forces can make bridges swing, and chimneys or similar slender and light structures oscillate. Oscillation occurs when the damping is small and the natural resonance frequency is close to the vortex shedding frequency. This can be eliminated by adding additional damping to the structure.
See what nature can do and watch the collapse of the suspending Tacoma Narrows Bridge in November 7, 1940.
Waves cause strong forces. Even huge platforms at sea suffer from it. Not only the danger of fatigue of the structure, but also unpleasant working conditions are problems to deal with. Tuned Mass Dampers have proven to be the solution to this problem. They reduce the movements caused by the waves to an acceptable level.
Resonances caused by earthquakes in structures can cause great amount of damage. A small movement of the surface of the earth can results in a big swing at the top of tall and slender structures. In these risk areas Tuned Mass Dampers protect slender structures like building constructions as chimneys from damage or collapse.
Flow Engineering Tuned Mass Dampers