Effectiveness of using tuned-mass dampers in reducing seismic risk

Strong earthquakes cause tangible and intangible seismic losses and disrupt service and function of buildings and infrastructure. The losses could be mitigated by increasing seismic design levels or by installing additional energy dissipation devices, such as tuned-mass dampers (TMDs). Although TMDs are useful for reducing structural responses, their effectiveness in terms of the expected lifecycle cost of buildings including the cost of TMDs, is rarely discussed. A parametric study on the expected lifecycle cost of a building with TMDs is carried out using a two-degree-of-freedom system whose non-linear hysteretic behaviour of the main structure is represented by the Bouc-Wen model. Probabilistic models of seismic demand to structures with TMDs are developed by using 381 ground motion records. The models are employed to assess the expected lifecycle cost of structures with TMDs and to investigate the effectiveness of TMDs in reducing seismic risk. The results indicate that the effectiveness of TMDs decreases as the seismic excitation level increases and its use on occasion could worsen structural performance against earthquake loading. The reduction in the expected damage cost in terms of the initial construction cost by installing TMDs is limited.