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2006-12-21 05:17:15 · 2 answers · asked by Mervin DePervin 2 in Science & Mathematics Engineering

Please don't just copy and paste web resources as a response. Also I wasn't asking what they were; I already know. Thanks,

MDP

2006-12-21 05:23:31 · update #1

2 answers

The dampers are installed for a reason, so I imagine if they failed, there'd be problems. I guess "building collapsing" is the problem on the forefront of most engineers' minds.

2006-12-21 05:35:14 · answer #1 · answered by Bugmän 4 · 1 0

A tuned mass damper is a device mounted in structures to prevent discomfort, damage or outright structural failure by vibration. Typically, the dampers are huge concrete blocks mounted in skyscrapers or other structures, and moved in opposition to the resonant frequency oscillations of the structure by means of springs, fluid or pendulums. High-tension lines often have small barbell-shaped Stockbridge dampers hanging from the wires . See also damping.

Small devices working on the same priciples were used as shock absorbers to damp rear wheel bounce on the Citroën 2CV.

Sources of vibration and resonance
Unwanted vibration may be caused by environmental forces acting on a structure, such as wind or earthquake, or by a seemingly innocuous vibration source causing resonance that may be destructive or unpleasant or simply inconvenient.
Earthquakes
The seismic waves caused by an earthquake will cause tall buildings to sway and oscillate in various ways depending on the frequency and direction of ground motion, as well as the height and construction of the building. When the seismic motion causes a harmonic oscillation in the frame of the building, where sections of the building are moving in opposing directions, it can result in structural failure.

Wind
The force of wind against tall buildings can cause the top of skyscrapers to move more than a metre. This motion can be in the form of swaying or twisting, and can cause the upper floors of such buildings to move. Certain angles of wind and aerodynamic properties of a building can accentuate the movement and cause motion sickness in people.

Mechanical human sources
Masses of people walking up and down stairs at once, or great numbers of people stomping in unison, can cause serious problems in large structures like stadiums if those structures lack dampening measures. Vibration caused by heavy industrial machinery, generators and diesel engines can also pose problems to structural integrity, especially if mounted on a steel structure or floor. Large ocean going vessels may employ tuned mass dampers to isolate the vessel from its engine vibration.

How they work
Tuned mass dampers stabilize against violent motion caused by harmonic vibration. The presence of a tuned damper forces a comparatively lightweight structure to overcome the inertia of a great mass, such as a giant concrete block, placed in such a way that the mass only begins to move in one direction just as the structure begins to move in the other, thus damping the structure's oscillation. The counterweight may be mounted using massive spring coils and hydraulic dampers, and if the axis of the vibration is fundamentally horizontal or torsional, leaf springs and pendulum-mounted weights are employed. Tuned mass dampers are engineered, or "tuned" to specifically counter harmful frequencies of oscillation or vibration.

2006-12-21 13:20:38 · answer #2 · answered by Melli 6 · 0 1

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