Taipei 101’s tuned mass damper during building construction.
On Saturday, August 8, Typhoon Soudelor hit Taipei. The storm put the 1,667-foot-tall Taipei 101 to the test and it came through with flying colors. The tuned mass damper (TMD) worked as building structural engineers Thornton Tomasetti and Evergreen, architect C Y Lee & Partners and TMD designer RWDI intended, even as it set a new record for motion during the event, swaying a full meter from its at-rest position in the 100 to 145 mile per hour wind gusts.
The TMD is a ball of stacked steel plates measuring 18 feet in diameter and weighing 728 tons, suspended above Floor 87 by cables anchored at Floor 92. Hydraulic cylinders linking the ball and Floor 87 are pushed and pulled as the ball sways. The TMD’s performance during Typhoon Soudelor compared closely with performance expectations established during design based on an initial analysis by RWDI.
A number of publications have discussed the record-breaking movement, but we have the added benefit of access to an engineer actually involved in the design of the TMD. Principal Len Joseph was able to provide some more specific explanations of damper movements, and how the damper worked to alleviate the sense of motion for tower occupants during this type of weather event.
This video, provided by RWDI, simulates TMD movements within the building during a large wind event. As Len explains, “The TMD is neither counterweight nor ballast, and does not actually move in opposition to the building. It does, however, move more than the building does, with its movements lagging those of the building—in essence, acting ‘out of phase’ with the building. As the gap between the TMD and the building opens and closes during an event such as the typhoon or an earthquake, that drives the damper cylinders. With each such movement the dampers convert some of the kinetic energy of the building to thermal energy, which reduces the amount of sway in subsequent cycles and results in an easier ride for building occupants.”
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