Frequency-based response of damped outrigger systems for tall buildings

Abstract

The outrigger structural system for tall buildings is known to be effective in reducing lateral drift under quasi-static wind loading. Although keeping lateral deflection below the required value is certainly important, it is found that in most tall buildings without supplementary damping, the design for stiffness is usually governed by occupant comfort under lateral acceleration. This thesis describes the concept of incorporating fluid viscous dampers in the outrigger system to add supplementary damping into the structure. A 40-story building installed with the variant outrigger system is analyzed for dynamic response due to wind effects such as buffeting and vortex shedding. By constructing an 80-dof discrete lumped mass model, and using a frequency-based response approach, two configurations of dampers, namely series and parallel damping are studied in detail. The effect of increasing damper size to overall achievable building damping is monitored for both configurations. Additionally, design and constructability issues with regards to the implementation of the systems are discussed.