Damper is designed to dissipate seismic or dynamic energy on a structure.
Dampers work in tension and compression. The dampers can reduce longitudinal and transverse or vertical displacement of a deck. They can be installed, for example, longitudinally between the deck and the abutment, or in transverse between the deck and the pier structure.
Dampers can be installed at different locations in a buildingfor brace isolation or base isolation systems. Seismic energy is dissipated in the damper unit instead of being dissipated in the concrete or steel structure.
Dampers can accommodate transverse and longitudinal seismic displacement,and at the same time allow longitudinal displacement such as creep shrinkage and thermal expansion or contraction of the structure.
This is Viscous Damper .It absorbs earthequake energy using viscous resistive force at the time when viscous fluid filled inside cylinder passes orifice and is used together with elastic suport to secure elasticity restoring force, also absorbing energy with resistive force of viscous fluid at the time of earthquake.