Michael Montgomery

Experimental Validation of Viscoelastic Coupling Dampers for Enhanced Dynamic Performance of High-Rise Buildings

AbstractA new damping system, the viscoelastic coupling damper (VCD), has been developed to enhance the wind and seismic performance of coupled shear wall high-rise buildings by adding high damping elements in place of reinforced concrete coupling beams. VCDs replace structural members, such as outriggers or coupling beams, and therefore do not occupy any usable architectural space. When they are properly configured in high-rise buildings, they provide supplemental viscous damping to all lateral modes of vibration, which mitigates building tenant vibration perception problems and reduces both the wind and earthquake response. Experimental results from tests on five small-scale viscoelastic (VE) damper specimens of 5- and 10-mm thicknesses are first presented, followed by the results from six full-scale VCDs representing two alternative configurations. The first was designed for areas where moderate seismic ductility is required, and the second was designed with built-in ductile structural fuses for areas ...

Thermal-Mechanical Model for Predicting the Wind and Seismic Response of Viscoelastic Dampers

AbstractThis paper presents a simplified coupled thermal-mechanical model for the modelling of viscoelastic dampers with temperature- and frequency-dependent properties subjected to long-term and short-term dynamic loading due to wind and earthquakes. In this numerical model, the self-heating effect caused by molecular-level friction in the viscoelastic (VE) material is captured explicitly using a finite volume thermal diffusion model based only on the physical properties of the steel and VE material. The thermal model is coupled to a single degree of freedom (SDOF) mechanical model, which produces an efficient computational scheme for time-history analyses of VE dampers under both long-term and short-term loading scenarios. The predictions from the proposed model are compared with full-scale experimental results of long-duration wind loading ranging from design level events to extremely rare events, and for shorter but more intense seismic loading scenarios. It is shown that results obtained using this p...

Analytical Study on the Dynamic Properties of Viscoelastically Coupled Shear Walls in High-Rise Buildings

AbstractAn 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 seismi...

Viscoelastic Coupling Dampers (VCDs) and Viscoelastic-Plastic Coupling Dampers (VPCDs) for enhanced efficiency and resilience of high-rise buildings

New damping systems, the viscoelastic (VE) Coupling Damper (VCD) and Viscoelastic-Plastic Coupling Damper (VPCD) has been developed to improve the performance of tall reinforced concrete (RC) buildings subject to both wind and earthquake loads. VCDs are introduced in lieu of RC coupling beams to take advantage of differential shear deformations between adjacent walls during lateral loading of the structure. The VCDs utilize multiple VE material layers that are bonded to alternating steel plates with each consecutive steel layer extending out to the opposite side and anchored into the walls using a number of alternate connection details. When the building is subject to frequent or design level wind storms or low level earthquakes, the damper exhibits both a displacement-dependent elastic restoring force providing coupling to the walls and a velocity dependent viscous force, providing supplemental damping to the building. In regions of severe seismicity, a ductile “fuse” element can also be included in the damper to enhance its performance. The “fuse” is capacity designed such that if predefined load levels are reached in the damper during extreme seismic loading, connection elements act as force limiting members and prevent damage from occurring in adjacent structural elements. The response during severe earthquakes is viscoelastic at small amplitudes and becomes plastic once the connections start yielding resulting in what is termed a Viscoelastic-Plastic (VEP) hysteresis. Replaceable connections are utilized to allow for repair or replacement after an earthquake. This paper describes the Viscoelastic and Viscoelastic-Plastic response of this new damping system and provides some examples of the design concept and applications of this technology.