The tuned mass damper used in Taiwan’s Taipei 101 tower represents an engineering feat that is so impressive the designers decided to make it publicly visible for all to see. Taipei 101’s 730-ton tuned mass damper may represent an extreme, but its purpose is the same as much smaller dampers that may be used in an office building or mall: to mitigate vibrations or sway that may otherwise alarm or cause discomfort to building occupants.
As building materials get lighter and designs push the limits of what is possible in architecture, structural vibrations are becoming more worrisome. A vibrating floor may not be dangerous, but it can certainly cause some unease among building occupants.
That’s where Mehdi Setareh, PhD, Professor, School of Architecture + Design at Virginia Tech’s College of Architecture and Urban Studies, comes in. With the help of a small team of students, he has created a portable tuned mass damper (PTMD) that weighs less than 275 pounds and is about the size of a shop vac. The device reduced vibrations by 40-75% in tests at Virginia Tech’s Vibration Testing Lab.
Mehdi Setareh next to an early version of the Portable Tuned Mass Damper. Courtesy Virginia Tech.
The PTMD can be incorporated in new construction or added as a corrective measure in an existing building. Even nontechnical personnel can tune the device, using a $5 iTunes application and Setareh’s instructions. Because of the device’s small size, it can be easily hidden in a cabinet or even within furniture.
Plates, springs, and dampers that are built into the two-foot-tall, 15-inch-wide box are tuned to the natural frequency of a structure and reduce vibrations by moving in the opposite direction of that structure, but at 10 to 20 times higher acceleration rates.
Currently, the unit shows the most promise for use in structures with high foot traffic, such as theaters, malls, nightclubs, and monumental staircases, or in settings that have vibration-sensitive equipment, such as hospitals and labs.
Setareh has applied for a patent on the device. He plans to place it on the market as a kit of parts with instructions on how to assemble, install, and tune the damper.