Integrated design methodology for isolated floor systems in single-degree-of-freedom structural fuse systems

Various researchers developed general design procedures for the design of structures with structural fuses (i.e., defined as metallic passive hysteretic energy dissipation (PED) devices which are disposable or can be easily replaced after a seismic event). The structural fuse concept, as implemented in these design procedures, requires to concentrate all the seismic damage in the structural fuses, while the bare frame hosting these devices behaves elastically during a seismic event. Past research showed that structures are stiffened when using PED devices as structural fuses, which correspondingly reduces the displacement demands on these structures. Therefore, one benefit of using structural fuses is that displacement sensitive non-structural components in such buildings can be better protected during seismic events. However, this past research also showed that this may also correspond to an increase in floor acceleration demands. To protect the acceleration sensitive equipments on the floors of such buildings, a possible solution may be to combine the stiffening of structures using PED devices with a strategy of introducing isolated floors in the rooms where such acceleration-sensitive equipment is located. This is the strategy investigated in this dissertation.;Two kinds of isolated floor systems were studied in this research. Characterization tests were first conducted on two kinds of isolated floor systems to define their mechanical behavior properties, from single isolators to complete systems. The experimentally obtained mechanical behavior was then simulated in computer programs. Models of single-degree-of-freedom (SDOF) structural fuse frames with implementation of these two isolated floor systems were developed. A number of parametric studies were then conducted on these combined systems to determine the preferred design parameter values to be used in the design of such structural fuse frames coupled with isolated floors, and to establish how the combined systems behave under different mass ratios of the isolated floor system to the base SDOF structural fuse structure. Finally, combined design concepts considering both the design of the base SDOF structural fuse structure and the design of the isolated floor system on top were developed for each kind of isolated floor system.