Madison Square Garden
New York City, United States
Tuned mass damper
5 TMDs on each of the 2 bridges
Madison Square Garden’s owners planned to suspend new viewing bridges from the ceiling of this famous performance venue. Hanging the bridges was safe – they could bear the required weight as designed – but because the building’s roof is cable-supported and inherently flexible, they’d be at risk of vibrating noticeably as people moved around on them, especially if fans were bouncing in time to music. We installed five TMDs on each bridge. For each damper, we needed five tons of mass to fit within a height of 14-1/2 inches – while leaving +/-2 inches’ clearance for the mass to move up and down. Only a lead-filled box would provide enough mass in such a small space. Our viscous-damper fabrication partners, ITT Enidine, optimized the properties of the fluid inside the hydraulic cylinders that controlled the movement of the masses. Being able to vary the fluid’s viscosity let us tune the TMDs to the right frequencies.