Dynamic field testing of a 15-year-old friction pendulum base-isolated residential building

This paper presents a landmark full-scale experimental program aimed at advancing the understanding of long-term performance of seismic base isolation for buildings in real service conditions. A three-story residential structure in Arischia (L'Aquila, Italy), base-isolated with Friction Pendulum (FP) bearings in service for over 15 years, was subjected to in-situ dynamic testing. Using custom-designed self-reacting frames and the EUCENTRE's mobile laboratory, displacement-controlled sinusoidal loading histories were applied, covering a range of amplitudes and peak velocities. This paper details the test specimen, experimental setup, loading protocols, and instrumentation. It presents preliminary findings on key isolation system properties, including post-elastic stiffness, static and dynamic friction coefficients, and equivalent damping ratio. These results provide rare field-based insight into the effects of aging on FP isolators and offer critical validation data for models used in performance-based assessment of base-isolated structures. In addition, the study demonstrates the feasibility and value of in-situ testing, which can serve as a model for future full-scale investigations of base-isolated buildings.