Tuned mass damper (TMD) — Den Hartog optimal tuning (f_opt = 1/(1+µ), ζ_opt = √(3µ/(8(1+µ)³))), mass ratio µ, frequency response with TMD, stroke limits, multi-degree TMD (MTMD), pendulum TMD, active and semi-active TMD (MR damper), TMD for wind-induced vibration (buildings, bridges), vortex-induced vibration (chimneys, cables), and examples (Taipei 101, Citigroup Center, Millennium Bridge).
