A study concerning the performance assessment and enhanced retrofit of public buildings\noriginally designed without any anti-seismic provisions is presented herein. Arepresentative structure\nbelonging to this class was demonstratively examined, i.e., a school built in Italy in the early 1970s,\nbefore a coordinate national Seismic Standard was issued. The building is characterized by a mixed\nreinforced concrete (ground storey)-steel (first and second storey) frame skeleton. An extensive\non-site experimental investigation was developed in the first step of the study, which helped identify\nthe mechanical characteristics of the constituting materials, and re-draw the main structural details.\nBased on these data, and relevant updates of the finite element model of the structure, the seismic\nassessment analyses carried out in current conditions highlighted several performance deficiencies,\nin both the reinforced concrete and steel members. An advanced seismic retrofit hypothesis of the\nbuilding was then designed, consisting of the installation of a set of dissipative braces incorporating\nfluid viscous dampers as protective devices. This solution makes it possible to attain an elastic\nstructural response up to the maximum considered normative earthquake level, while at the same\ntime causing more limited architectural intrusion and lower costs as compared to conventional\nrehabilitation strategies.
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