After the base building was complete, the windows falling from the John Hancock Tower garnered the press, but frame stability and sway under wind loads captured LeMessurier’s attention. Hired specifically to reduce the building response during wind events, LeMessurier designed a dual Tuned Mass Damper system to increase structural damping. When excessive motion is detected, the two TMDs are activated in opposing directions to tame the natural twisting of the building’s elongated shape.