Foundation, Concrete and Earthquake Engineering

W-EQ Coupling Dampers: A Unique Damper from Nippon Steel Engineering Co.

W-EQ Coupling Dampers are introduced at key locations instead of a number of coupling beams to add distributed viscous damping, which reduces wind and earthquake vibrations including accelerations, velocities and displacements (drifts) as well as the overall design forces. W-EQ Coupling Dampers lead to more efficient designs and increased safety and resilience against large hurricanes and earthquakes. 

It consists of multiple layers of viscoelastic material alternating between layers of steel plates with each consecutive plate extending out to the opposite side. The plates are then anchored into structural members using a number of different connection details. When the W-EQ Coupling Dampers are configured into the structural system (coupling beams, core walls and outriggers, amongst others) at strategic locations they can significantly increase the level of distributed damping of the building without occupying any architectural space.
Full-scale tests of the W-EQ Coupling Damper- conducted for
 both wind and earthquake applications for realistic high-rise building 
load conditions
 Full-scale tests of the W-EQ Coupling Damper- conducted for both wind and earthquake applications for realistic high-rise building load conditions
When viscoelastic material is deformed it provides a velocity-dependent viscous restoring force, which adds damping to the structure, as well as a displacement-dependent elastic restoring force. The W-EQ Coupling Dampers are placed horizontally between large structural walls which are extremely effective locations, because of the significant levels of shear distortions in the viscoelastic material caused by the relative motion of the walls under lateral vibrations. Also, because the W-EQ Coupling Dampers replace coupling beams they do not take up any valuable leasable space like traditional vibration absorbers.

Design Benefits 
Incorporating W-EQ Coupling Dampers can reduce structural materials over the height of the structure or an increase in the number of stories for a given structural configuration. As opposed to commonly used vibration absorbers, W-EQ Coupling Dampers do not take up valuable leasable space at the top of the structure and do not require monitoring, maintenance or tuning over the life of the structure to ensure adequate performance. W-EQ Coupling Dampers can also be used to reduce both wind and earthquake induced vibrations.
Positioning of  W-EQ Coupling Damper
Positioning of W-EQ Coupling Damper
Performance against Seismic Vibrations 

W-EQ Coupling Dampers reduce earthquake induced vibrations through added damping to the lateral modes of vibration. W-EQ Coupling Dampers are capacity designed such that if predefined load levels are reached during an extreme seismic loading W-EQ Coupling Damper connecting elements act as structural fuse elements and prevent damage from occurring in adjacent structural elements. After an extreme earthquake, the W-EQ Coupling Dampers can be inspected and if the structural fuse elements were activated, they can easily be repaired or replaced. The W-EQ Coupling Dampers can enhance the dynamic performance significantly and decrease the time to occupancy or level of repair after an earthquake.

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