How it works
To counteract building sway effectively, the pendulum must have the same natural period as the building. The period of a simple short-stroke pendulum system relates directly to the square root of the active length of the pendulum; that is, to the square root of the distance from the pivot to the point where you can consider the mass concentrated. By directing the pendulum to operate in the plane in which the building sways, and at a length that produces the same natural period as that of the structure, forces from damping-mass acceleration and deceleration counteract structure sway.