Seismic performance and sensitivity of floor isolation systems in steel plate shear wall structures

Seismic floor isolation is a method for protecting nonstructural components, equipment and/or valuable building content in traditional fixed base buildings. Seismic floor isolation is achieved by isolating a secondary floor system from the primary structural floor using horizontally flexible elements called isolators. The nonstructural components, equipment and/or valuable building content is placed atop the secondary, isolated, floor system thereby decoupling the isolated component from the floor motion of the primary structural system. Though there is no codified procedure for designing floor isolation systems, the primary difference from traditional base isolation systems is the seismic input and the weight on the isolation system. s paper results of a numerical study to investigate the performance and sensitivity of floor isolation systems (FISs) designed for the upper levels of multi-story steel plate shear wall frames are presented. The sensitivity of the performance of the FIS to variations in the steel plate shear wall’s web-plate strength and stiffness is investigated. The results of the study show FISs are able to effectively limit, on average, absolute acceleration demands on equipment in the upper levels of multi-story buildings though isolator displacement demands can be large. Further isolator displacement demands and absolute acceleration demands on the equipment are shown to be insensitive to variations in the steel plate shear wall’s material and geometric properties.