Energy Dissipation Dampers

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ENERGY DISSIPATION DAMPERS

SUB : EARTHQUAKE RESISTANT ARCHITECTURE

PRESENTATED BY : TANVI GARG (2008UAR133)


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INTRODUCTION

ACTIVE ENERGY DISSIPATION DEVICES - Active control systems sense and resist

building motion, either by applying external force or by modifying structural properties of

active elements.

PASSIVE ENERGY DISSIPATION DEVICES - add damping (and sometimes stiffness)to the building. Ideally, energy dissipation devices dampen earthquake excitation of the

structure that would otherwise cause higher levels of response and damage to

components of the building.

CONCEPTUALLY, isolation reduces response of the superstructure by decoupling the

building from the ground. Typical isolation systems reduce forces transmitted to the

superstructure by lengthening the period of the building and adding some amount of

damping.

Among the most important advanced techniques of earthquake resistant design and

construction are: Base Isolation

Sliding systems

Energy damping Devices


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BASE ISOLATORS


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ENERGY DAMPING DEVICES

DAMPING DEVICES AND BRACING SYSTEMS

Damping devices are usually installed as part of bracing systems, with one end attached to

a column and one end attached to a floor beam. Primarily, this arrangement provides

the column with additional support. Most earthquake ground motion is in a horizontal

direction; so, it is a buildings columns which normally undergo the

most displacement relative to the motion of the ground.

When seismic energy is transmitted through them, dampers absorb part of it, and thus

damp the motion of the building.


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ENERGY DAMPING DEVICES - TYPES

Damping devices that have been developed can

be grouped into three broad categories:

Friction Dampers: these utilize frictional forces to

dissipate energy (energy is absorbed by surfaces

with friction between them rubbing against each

other)

Metallic Dampers : utilize the deformation of metal

elements within the damper (energy is absorbed

by metallic components that yield)

Viscoelastic Dampers : utilize the controlled

shearing of solids (energy is absorbed by utilizing

the controlled shearing of solids)

Viscous Dampers: utilized the forced movement of

fluids within the damper (energy is absorbed by

silicone-based fluid passing between piston

cylinder arrangement)


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FLUID VISCOUS DAMPER

A fluid viscous damper resembles the common shock absorber such as those found inautomobiles.

The piston transmits energy entering the system to the fluid in the damper, causing it to

move within the damper.

The movement of the fluid within the damper fluid absorbs this kinetic energy by

converting it into heat.

energy dissipation is achieved through the use of a moving piston in a hollow cylinderfilled with a silicone-based fluid compound, which is forced to pass through small orifices

around and through the piston head. Energy is transformed into heat due to friction


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METALLIC DAMPERS

In these devices, energy dissipation is based on the ability of metals to undergo numerousinelastic cycles until failing and therefore to absorb significant amounts of energy.

Metallic dampers are usually made from steel.

They are designed to deform so much when the building vibrates during an earthquake that

they cannot return to their original shape.

This permanent deformation is called inelastic deformation, and it uses some of the

earthquake energy which goes into building. It is the stiffness ratio rather than the ductility ratio that has a greater effect on the

performance of the devices under seismic loading.
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FRICTION DAMPERS

In this case, energy is dissipated by the friction that is generated due to the sliding of twosolid materials against each other.

Friction dampers are designed to have moving parts that will slide over each other during a

strong earthquake. When the parts slide over each other, they create friction which uses

some of the energy from the earthquake that goes into the building.

The damper is made up from a set of steel plates, with slotted holes in them, and they are

bolted together. At high enough forces, the plates can slide over each other creatingfriction. The plates are specially treated to increase the friction between them.
http://www.ideers.bris.ac.uk/resistant/damping_friction.htmlhttp://www.ideers.bris.ac.uk/resistant/damping_friction.htmlhttp://www.ideers.bris.ac.uk/resistant/damping_friction.htmlhttp://www.ideers.bris.ac.uk/resistant/damping_friction.html


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FRICTION DAMPERS


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TUNED MASS DAMPER

Tuned mass dampers (TMD) employmovable weights on some sort of springs.

These are typically employed to reduce

wind sway in very tall, light buildings.

Typically, the dampers are huge concrete

blocks or steel bodies mountedin skyscrapers or other structures, and

moved in opposition to the resonance

frequency oscillations of the structure by

means of springs, fluid or pendulums.


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DIFFERENCE

METALLIC DEVICE VISCOUS DEVICE

The metallic device is referred to as

a rate-independent device.

The metallic device is rateindependent since the resisting force

in the device is a function only of the

relative displacement across the

device.

The viscous device is classified as a

rate-dependent device.

The viscous device is ratedependent since the resisting force in

the device is dependent, in part or in

full, on the relative velocity across the

device

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Energy Dissipation Dampers