Dynamic In-Situ Testing of a 15-Year-Old Friction-Pendulum Base Isolation System

Base isolation systems represent one of the most effective strategies for the seismic protection of buildings and infrastructure, applicable to both new constructions and retrofitting projects. Base isolation has received significant attention over the past few decades that led to remarkable improvements of this technology, resulting in the progressive deployment of better performing devices. Despite these significant advancements, the current understanding of the performance of isolated structures primarily stems from component-level testing of brand-new isolation bearings, while comprehensive studies on the long-term behavior of base isolation systems, particularly involving large groups of isolators in real-world applications, remain limited. The PASFIT project, introduced in this paper, addresses this knowledge gap by conducting extensive dynamic field testing of a 15-year-old base-isolated residential building equipped with 32 single-friction-pendulum bearings. This unique experimental program offers two key benefits: evaluating the performance of an entire group of base isolators under real-world conditions and providing valuable data for an in-depth analysis of the overall structural response of both the building and the isolation system, particularly in relation to material aging and natural deterioration over time. This paper presents an overview of the PASFIT project, detailing the efforts undertaken to successfully complete its ambitious experimental activities. Preliminary results are summarized at the end of the paper and contextualized within the broader objectives of quantifying isolation system degradation and validating its long-term reliability.