Seismic damage and fragility analysis of structures with tuned mass dampers based on plastic energy

The effectiveness of using a tuned mass damper (TMD) to improve a structure's ability to dissipate earthquake input energy is investigated through the use of seismic fragility curves. The nonlinear material behaviour of the structure is captured using the force analogy method, the backbone for analytically quantifying plastic energy dissipation in the structure. Numerical analysis was performed to study the global response and local energy dissipation of a six-storey moment-resisting steel frame with and without a TMD installed for 100 simulated non-stationary Gaussian earthquake ground motions. The effectiveness of the TMD, based on reduction of seismic responses and enhancement of the seismic fragility, is considered at structural performance levels for immediate occupancy and life safety as identified in FEMA 440. An equivalent monotonic plastic strain approacha local measure of structural damageis used to correlate the seismic fragilities at different global performance levels based on storey drift. Results illustrate that a TMD can enhance the structure's ability to dissipate energy at low levels of earthquake shaking, while less effective during moderate to strong earthquakes, which can cause a significant period shift associated with major structural damage. This de-tuning effect suggests that an extremely sizable TMD is not effective in reducing damage of a structure. Published in 2010 by John Wiley & Sons, Ltd.