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1) Vibration reduction of pedestrian bridges

4. Dampers in bridges

long span structures with high dynamic susceptibility

+

mass dampers

=

reduction of vibration amplitudes (5x)

abia Kadka, Wrocaw

- one span

- suspended

- 56,52m long, 3,11m wide

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Dampers are the most economical and appriopriate way to control

vibration of light objects.

GENERAL RULE:

Installation ofmass spring viscous damper

type of damper with natural frequency close to

footbridge frequency.

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4. Dampers in bridges

Fig.1 Static scheme and geometry of footbridge

In order to change dynamic characteristic of a footbridge three dampers of a

mass spring viscous dampertype were installed.

, span: dampers with natural frequency 1.2Hz, vibrating mass 935kg,

total mass 1120kg

span: damper with natural frequency 1.4Hz, vibrating mass 2310kg,

total mass 2410kg

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4. Dampers in bridges

Fig.2 Scheme of bridge - damper system

Mass dampers consist of:

block of steel plates which forms vibrating mass (thanks to interchangable

plates it is possible to tune a damper to natural frequency of any bridge),

system of springs with certain stiffness,

viscous dampers to ensure damping in a system.

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2) Solution for bridges and elevated highways

4. Dampers in bridges

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2) Solution for bridges and elevated highways

4. Dampers in bridges

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2) Solution for bridges and elevated highways

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2) Solution for bridges and elevated highways

4. Dampers in bridges

The rubber bearing take the vertical forces while

the friction dampers damp the horizontal forces

during earthquakes

Rubber Bearing Friction Damper

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3) Dampers for cables in cable stay bridges

4. Dampers in bridges

Different models:

one cable damper

two cables damper

four cables damper

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3) Dampers for cables in cable stay bridges

4. Dampers in bridges

FOUR cables damper

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3) Dampers for cables in cable stay bridges

4. Dampers in bridges

FOUR cables damper

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3) Dampers for cables in cable stay bridges

4. Dampers in bridges

TWO cables damper

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3) Dampers for cables in cable stay bridges

4. Dampers in bridges

TWO cables damper

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3) Dampers for cables in cable stay bridges

4. Dampers in bridgesFILM

http://localhost/var/www/apps/conversion/tmp/scratch_1/one%20dampers.avihttp://localhost/var/www/apps/conversion/tmp/scratch_1/one%20dampers.avi

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3) Dampers for cables in cable stay bridges

4. Dampers in bridges

ONE cable damper