How the Viscoelastic Coupling Damper (VCD) Technology Works
The VCD is a ground breaking technology that adds distributed viscous damping to high-rise buildings. The VCD was developed at the University of Toronto in collaboration with leading high-rise designers and validated through full-scale testing.
VCDs consist 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. The system can be adapted to the most common structural configurations such as coupling beams, core walls and outriggers, amongst others. When the VCDs are configured into the structural system at strategic locations they can significantly increase the level of distributed damping of the building without occupying any architectural space.
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 VCDs 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 VCDs replace coupling beams they do not take up any valuable leasable space like traditional vibration absorbers.
Benefits of Viscoelastic Coupling Dampers for High-Rise Design
Performance Benefits: When VCDs are introduced at key locations instead of a number of coupling beams they add distributed viscous damping, which reduces wind and earthquake vibrations including accelerations, velocities and displacements (drifts) as well as the overall design forces. VCDs lead to more efficient designs and increased safety and resilience against large hurricanes and earthquakes.
Overall Design Benefits: Incorporating VCDs 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, VCDs 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. Viscoelastic Coupling Dampers can also be used to reduce both wind and earthquake induced vibrations.
Damping in Tall Structures
Tall structures have very low levels of inherent damping. Recent measurements have shown the inherent damping of tall structures to be less than 1% of critical making them extremely sensitive to lateral wind and earthquake vibrations. Utilizing these inherent damping design assumptions commonly used in the past can lead to designs with higher vibration levels and lower factors of safety.
Enhanced Wind Performance
VCDs reduce tenant motion perception caused by wind induced lateral accelerations and torsional velocities. VCDs also reduce drifts and wind design loads leading to more efficient designs and increased safety against large hurricanes and wind storms.
Enhanced Earthquake Performance
VCDs also reduce earthquake induced vibrations through added damping to the lateral modes of vibration. VCDs are capacity designed such that if predefined load levels are reached during an extreme seismic loading VCD connecting elements act as structural fuse elements and prevent damage from occurring in adjacent structural elements. After an extreme earthquake, the VCDs can be inspected and if the structural fuse elements were activated, they can easily be repaired or replaced. The VCD can enhance the dynamic performance significantly and decrease the time to occupancy or level of repair after an earthquake.
VCDs are manufactured by worldwide construction leaders Nippon Steel Engineering Co. (NSEC). NSEC is a worldwide leader in quality construction and technological innovation and have manufactured viscoelastic dampers for seismic and wind applications in Japan and Taiwan for over 20 years. Viscoelastic materials have been used for over 40 years in high-rise building applications to mitigate wind vibrations and have shown good aging characteristics.
Viscoelastic Coupling Dampers Testing and Validation
The VCD has been thoroughly tested and validated at the University of Toronto Structural Testing Facilities and the Structures Laboratories at Ecole Polytechnique in Montreal.
Over 250 test results have been carried out to characterize the viscoelastic material for low to high level wind and earthquake events. In addition to this, the manufacturer of the VCD has test data from over 1000 tests of the viscoelastic material for many different loading scenarios.
Over 300 full-scale tests of the VCD were conducted for both wind and earthquake applications for realistic high-rise building load conditions. High cycle fatigue tests as well as ultimate tests of the connections of the VCD have been conducted.
Viscoelastic Coupling Damper Experimental Validation Videos
Kinetica Viscoelastic Coupling Damper Services
Kinetica engineers can assist you with:
- Preliminary conceptual design using VCDs
- Detailed project specific VCD design
- Development of lateral load resisting schemes incorporating VCDs
- Full support for modeling and analysis techniques using VCDs
- Test data and modeling parameters
- Pricing and scheduling for the delivery of VCDs
To ensure you do not miss out on the opportunity to assess if this ground breaking technology can apply to your high-rise designs please Contact Us