Soaring 1396 feet above Manhattan, 432 Park Avenue became the third tallest building in the United States when it was completed in December 2015. With an especially slender aspect ratio of 15:1, the tower required sway control measures even for regularly occurring winds, making a TMD solution essential. Needing to fit the damping system into a relatively small space, the Motioneering team modified an innovative opposed-pendulum design concept we’d used on earlier projects. We divided the required 1200-ton mass into two identical 600-ton TMDs and equipped each TMD with three separate pendulums – two conventional, one inverted.

This configuration caused the masses to swing slowly but with sufficient force to be effective. The three-pendulum design resulted in a stable system that matched the tower’s frequency and fit within its space constraints, requiring less than half the height of a conventional design. This TMD enabled the building’s designers to address wind-induced motion issues without adding expensive structural materials or sacrificing valuable penthouse-level interior space.