Seismic Retrofit of Structures Using Hybrid Steel Slit–Viscoelastic Dampers

A hybrid steel slit–viscoelastic damper (HSVD) has been developed to enhance seismic performance of a structure. To model viscoelastic behavior, an analytical model is developed based on the Kelvin–Voigt and Bouc–Wen–Baber–Noori (BWBN) models. Experimental studies are conducted to find out the behavior of the viscoelastic material and the hybrid damper, and to validate the analytical model. Various seismic performance indices are evaluated using a three-story moment-resisting frame before and after seismic retrofit with the steel slit dampers and HSVDs. Fragility analysis is then carried out to investigate the exceedance probability of specified limit states, which shows that adding a viscoelastic part to the steel slit damper successfully improves the performance of the steel slit dampers. Finally, it is observed that the use of the capacity and demand diagram procedure is effective in preliminary design of the hybrid dampers to meet a desired target performance goal.