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SUMMARY As high‐rise buildings are built taller and more slender, their dynamic behavior becomes an increasingly critical design consideration. Wind‐induced vibrations cause an increase in the lateral wind design loads, but more importantly, they can be perceived by building occupants, creating levels of discomfort ranging from minor annoyance to severe motion sickness. The current techniques to address wind vibration perception include stiffening the lateral load‐resisting system, adding mass to the building, reducing the number of stories, or incorporating a vibration absorber at the top of the building; each solution has significant economic consequences for builders. Significant distributed damage is also expected in tall buildings under severe seismic loading, as a result of the ductile seismic design philosophy that is widely used for such structures. In this paper, the viscoelastic coupling damper (VCD) that was developed at the University of Toronto to increase the level of inherent damping of tall coupled shear wall buildings to control wind‐induced and earthquake‐induced dynamic vibrations is introduced. Damping is provided by incorporating VCDs in lieu of coupling beams in common structural configurations and therefore does not occupy any valuable architectural space, while mitigating building tenant vibration perception problems and reducing both the wind and earthquake responses of the structure. This paper provides an overview of this newly proposed system, its development, and its performance benefits as well as the overall seismic and wind design philosophy that it encompasses. Two tall building case studies incorporating VCDs are presented to demonstrate how the system results in more efficient designs. In the examples that are presented, the focus is on the wind and moderate earthquake responses that often govern the design of such tall slender structures while reference is made to other studies where the response of the system under severe seismic loading conditions is examined in more detail and where results from tests conducted on the viscoelastic material and the VCDs in full‐scale are presented. Copyright © 2013 John Wiley & Sons, Ltd.

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Viscoelastic coupling dampers (VCDs) are installed in lieu of traditional reinforced concrete (RC) coupling beams in high-rise buildings to provide distributed supplemental damping for all dynamic loading conditions without affecting the architectural layout. When distributed effectively over the height of the building, VCDs provide viscous damping in all lateral modes of vibration and an elastic restoring force that enhances the lateral stiffness of the coupled system. In this paper, a first extensive numerical case study is carried out to compare the seismic performance of a conventional coupled shear wall high-rise building to a high damping alternate of the same design in which VCDs replace all diagonal RC beams in the core to enhance its seismic resilience. The added damping from VCDs is intended to reduce the peak responses under low amplitude earthquakes, but for larger amplitude maximum credible earthquakes, the peak responses are similar; however, structural damage is greatly reduced. Three seismic hazard levels were investigated, and the results indicate that the use of VCDs reduces peak floor accelerations, story drifts, and story shears over all seismic intensities. Nonlinear time-history analysis results also highlighted the improved resilience of the VCD structure at the maximum credible seismic hazard level where the use of VCDs eliminated all damage to coupling beams that would otherwise require repair over most of the height of the building.

An innovative method of using viscoelastic (VE) dampers as coupling members between reinforced concrete shear walls has been recently developed for enhancing the wind performance and seismic resilience of tall buildings. Although three-dimensional finite-element models are used for the final design of such systems, fundamental analytical models that can be used to gain broader insights into their dynamic response have not yet been developed. Therefore, in this paper a sixth-order partial differential equation governing the dynamic properties of tall shear walls coupled using VE dampers is derived by explicitly taking into account the stiffness of the connecting elements as well as that of the slab directly above the dampers. The governing equation is solved numerically using the Taylor series expansion method and the periods and added damping ratios in various modes of vibration are evaluated. It is found that for given frequency independent VE material properties, the added damping ratios of such systems are independent of the mass of the building. Analyses using a commercially available VE damper by taking into account the frequency dependency of the VE material revealed that progressively higher maximum damping ratios are achieved in higher modes of vibration. Based on the conclusions derived through the analytical formulation, recommendations are provided for enhancing the efficiency of VE dampers in tall buildings.