Dottorato in INGEGNERIA STRUTTURALE E GEOTECNICA

Titolo della tesi: Totally or Partially Precast Constructions: Development, Engineering and Test of Seismic Protection Devices

Precast reinforced concrete buildings are widely employed for industrial and commercial purposes due to their construction efficiency, cost-effectiveness and modular assembly. However, these systems exhibit inherent seismic vulnerabilities, particularly at beam-to-column connections and panel interfaces, where limited ductility and inadequate energy dissipation capacity represent critical issues. In this study, a framework is introduced to propose a novel seismic-resisting concept for precast systems through the integration of steel hysteretic devices, enabling controlled plasticity and low-damage performance under seismic loading. The proposed solution includes Reverse Hysteretic Multiple-Arch Devices (RH-MADs) at beam-column joints to enable moment-resisting behavior, while Hysteretic Multiple-Arch Devices (H-MADs) can be applied at column bases or vertical interfaces to protect the main structural members. Precast beams are detailed and designed to enhance elastic behavior during design-level earthquakes, while nonlinear behavior is concentrated within easily replaceable steel devices, thereby enhancing safety and reducing economic losses. This research provides analytical derivations, multi-level numerical modeling and experimental validation. Initial formulations and simplified numerical models allow derivation of parametric design charts and definition of preliminary design criteria. Models are progressively refined through advanced simulations enabling precise calibration against experimental results and supporting both geometry-based and topology-driven optimization of hysteretic devices, aiming to achieve uniform plasticity distribution. Complete structural system is subsequently implemented in two- and three-dimensional frameworks to assess global seismic performance. Nonlinear static analyses confirm the formation of controlled plastic mechanisms within devices, while nonlinear time-history simulations demonstrate capacity of proposed moment-resisting frame to dissipate seismic energy through localized yielding of sacrificial components. In addition, efficacy of the proposed system in delaying yielding in primary structural members is enhanced by designing a precast frame equipped with H-MAD systems, thus ensuring a more favorable distribution of inelastic demand and reducing global displacement demand through increased hysteretic energy dissipation, in accordance with performance objectives defined by contemporary seismic design methodologies for precast reinforced concrete buildings. Experimental campaigns are finally conducted on custom-designed steel specimens and full-scale RH-MAD prototypes to validate their ability to sustain large inelastic deformations and develop stable hysteretic responses, consistently with the mechanical behavior predicted by the corresponding numerical models. Digital Image Correlation technique is further employed to capture high-resolution strain fields, enabling accurate identification of material properties and supporting calibration of numerical simulations.