Seismic isolation is a technique that reduces the seismic demand on structures damping the energy transmission from the soil to the building, has gained widespread use in both new constructions and seismic retrofitting of existing buildings and bridges. The 2018 Italian Standard (NTC 2018), in alignment with Eurocodes, provides updated guidelines for such retrofitting efforts. This paper presents a case study of a seven-story reinforced concrete building in southern Italy, constructed in the 1960s, that is retrofitted using double friction pendulum base isolators. While these isolators greatly enhance the building’s seismic performance, their implementation presented uplift challenges, which were resolved through a customized design strategy. A nonlinear time-history analysis, using three seismic records, was conducted to evaluate the post-retrofit response, with particular focus on uplift control, as well as reductions in acceleration and interstory drift, improving the building’s seismic performance according to current standards.

The original structure, though designed for seismic forces, did not meet current Italian standards due to advancements in engineering practice and increased design demands. For this retrofit, considering the structure's classification as Class IV, Peak Ground Acceleration (PGA) values of 0.28g and 0.3g were applied to meet the Life Safety Limit State (LSLS, return period of 950 years) and Near Collapse Limit State (NCLS, return period of 1,950 years). The retrofit was conducted following Level of Knowledge LC2 as required by NTC 2018, ensuring rigorous compliance with safety and assessment standards. Final verifications showed the ζ_E parameter exceeding 100%, indicating a considerable safety margin. The building, therefore, fully meets current seismic safety standards and demonstrates the effectiveness of seismic isolation in enhancing the resilience of existing structures.