EVALUATION OF THE INTER-STORY ISOLATION SYSTEM APPLIED TO AN EXISTING MASONRY SCHOOL BUILDING

Adding extra stories to an existing building is an interesting application of the Inter-story Isolation System (IIS) that allows to improve the seismic response of existing structures. Assuming that the isolated superstructure is much stiffer than both the isolation system and the existing structure, it behaves like a rigid body, acting as a Tuned Mass Damper for the substructure. Various methods are available in the literature for defining the optimal parameters of the isolation system, but only a few studies focused on this particular application with real case studies. In this paper, this application is shown for an existing masonry school building. The aim of the intervention is to raise the structure, increasing the space available for teaching activities, while also obtaining an improvement in the overall seismic behaviour of the substructure. First, an optimization for calculating the optimal IIS parameters is performed; then, based on the optimal results obtained, the effectiveness of the IIS application is evaluated by performing Time History Analysis, using a set of spectrum-compatible natural records and an equivalent-frame modelling (EFM) of the structure, and comparing the results obtained with and without the IIS.