Preserving Heritage through Innovation: Seismic Retrofit of a Masonry Bell Tower Using Fiber-Reinforced Composites

Historic masonry bell towers are among the most vulnerable cultural assets in seismic regions, due to their slender geometries, heterogeneous construction (at different ages), and material decay. This study presents the seismic retrofit of San Domenico’s church bell tower in southern Italy through the innovative combination of passive and active composite systems. A comprehensive diagnostic campaign, associated with a drone-aided photogrammetry survey of the geometry, was performed. Results revealed critical vulnerabilities associated with partial overturning and vault thrust, justifying a hybrid strengthening strategy. Passive composite-reinforced mortar systems were applied to vaults to improve shear capacity and limit crack propagation, while carbon fiber-reinforced polymer horizontal ties ensured boxlike behavior. In addition, active prestressed carbon cords introduced stabilizing compressive forces, significantly reducing the global overturning susceptibility. This study establishes a replicable model for combining seismic safety and conservation ethics, demonstrating that heritage structures can evolve into adaptive systems resilient to future seismic events.