The seismic design of optimal damped outrigger structures relies on the assumption that most of the input energy will be absorbed by the dampers, whilst the rest of the structure remains elastic. When subjected to strong earthquakes, nevertheless, the building structure may exhibit plastic hinges before the dampers begin to work. In order to determine to which extent the use of viscously damped outriggers would avoid damage, both the host structure's hysteretic behaviour and the dampers' performance need to be evaluated in parallel. This article provides a parametric study on the factors that influence the distribution of seismic energy in tall buildings equipped with damped outriggers: First, the influence of outrigger's location, damping coefficients, and rigidity ratios core-to-outrigger and core-to-column in the seismic performance of a 60-story building with conventional and with damped outriggers is studied. In parallel, nonlinear behaviour of the outrigger with and without viscous dampers is examined under small, moderate, strong, and severe long-period earthquakes to assess the hysteretic energy distribution through the core and outriggers. The results show that, as the ground motion becomes stronger, viscous dampers effectively reduce the potential of damage in the structure if compared to conventional outriggers. However, the use of dampers cannot entirely prevent damage under critical excitations. KEYWORDSdamped outrigger, energy distribution, hysteretic energy, strong earthquakes, tall buildings, viscous damper 1 | INTRODUCTION Outrigger systems consist of a series of cantilever truss beams or shear walls connecting the building core with the perimeter columns. As a result, the axial forces acting at the end of the outriggers help the reduction of the total deflection of tall buildings by increasing the restoring moment.Dampers have been introduced between the perimeter columns and the outriggers, resulting in an increase in the overall damping of the building, instead of an increase of static stiffness and strength. [1] A well-known first implementation of this system in twins' 60-story buildings is reported in Willford and Smith. [2] Park et al. [3] reported the installation of damped outriggers in a 68-story tower in South Korea. In a recent review, [4] Smith reported two more applications of damped outriggers in tall buildings. All the authors point out that the addition of supplementary damping systems not only reduced the overall vibration response, but also construction costs.Numerical and experimental studies have been conducted to extend these damper-based control capabilities towards an improved reduction of the dynamic response, [3,[5][6][7] including seismic scenarios. [8][9][10][11][12][13][14][15][16][17] However, few studies explore the performance of damped outriggers under strong earthquake motion. Generally, studies are based on the use of peak ground acceleration (PGA) values up to 0.4 g, whereas strong earthquakes may exhibit PGAs of about 1.0 g. At the same time, most of the resea...

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Structural Design, Architectural Engineering and Technology, Faculty of Architecture and the Built Environment, TU Delft, Delft, the NetherlandsAs of today, about 80 buildings equipped with active or semi-active devices for wind and earthquake-induced motion control have been reported. In the first part of this technical note, full-scale applications are reviewed to investigate whether large and severe earthquake levels were targeted as control objectives. In the second part, not yet implemented research studies (2011 -2014) are reviewed. The main conclusion is that strategies integrating control and structural design are the key for implementing large earthquake-target control devices in buildings.

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