GERB Vibration Control Systems, Inc, Berlin
The slender design of a 240-meter-tall tower structure requires additional structural damping to reduce vortex shedding-induced vibrations. Wind tunnel tests indicate that wind speeds can produce critical accelerations at the observation deck on the tower's top level. The resulting displacements not only cause issues regarding fatigue initiation at the concrete core of the tower, but also create discomfort for visitors. To mitigate critical displacements, a state-of-the-art, passive Tuned Mass Damping (TMD) system solution was implemented.
The primary uses of the tower include serving as an observation deck to visitors, as well as acting as a testing facility for various types of equipment under real-life conditions, which include building sway. For testing purposes, the TMD system is required to be either inactive or to artificially excite the tower in its fundamental mode of vibration. Further requirements are to produce controlled building sway in a defined direction. To satisfy these requirements, a novel dual-purpose active/passive TMD system was developed. This hybrid TMD is capable of suppressing the occurring vibration in one direction, while with the aid of a control algorithm excites the tower’s perpendicular direction.