Seismic and wind load response control of structures by using combinations of different energy-absorbing devices

Adding passive control devices to structures is often a cost-effective way to reduce the effects of externally applied loads especially the vibrations induced by the seismic and wind forces. The philosophy of passive control devices is to either add additional damping to a structure to dissipate the input energy or to change the structure's fundamental dynamic behavior to reduce the amount of input energy.; This dissertation emphasizes the reduction of critical peak responses of building structures due to seismic loading and resonant responses due to wind loading. Three commonly used passive control devices are studied: friction, fluid (viscous), and viscoelastic dampers. The responses of a ten-story steel frame structure implemented with added dampers is studied through finite element modeling. The roles of bracing members supporting the dampers is also addressed.; Results by using the 10-story building show that the friction dampers provide an excellent critical-peak-response reduction function. Spectrum analysis indicates that friction dampers are able to distribute input energy from the resonant frequency to a wide frequency range. They are effective passive devices to reduce seismic response.; By combining different dampers, various new devices can be created. In this study, friction-fluid and friction-viscoelastic dampers, which are intended to reduce the responses of wind and seismic loadings simultaneously, are examined. They have been shown to provide significant reduction for both wind load acceleration responses and seismic displacement responses by using the 10-story building. Furthermore, it is shown that devices with combined dampers can retain the advantages of different individual damper types. Therefore, they provide design flexibility in practical applications in which a broad range of damping behavior can be provided.