Towards Scalable and Rapid Seismic Vulnerability and Deterioration Assessment of Heterogeneous Building Stocks: Simplified Methodologies and Innovative Tools

The safety and resilience of the built environment are increasingly challenged by the coexistence of multiple risks. In seismic-prone countries such as Italy, a large share of the building stock was constructed before the introduction of modern seismic codes, making seismic vulnerability a persistent concern. At the same time, material degradation caused by ageing, environmental exposure and insufficient maintenance progressively reduces structural capacity and often amplifies seismic fragility. Despite the relevance of both hazards, methodologies for portfolio-scale assessment and prioritisation rarely address them in an integrated way. This thesis develops and applies a suite of methodologies to bridge this gap, with the overarching goal of providing harmonised, scalable and technically robust tools for the management of heterogeneous building stocks. First, a two-level methodology is introduced for the seismic prioritisation of large portfolios. The first level relies on deficiency-based forms that capture vulnerabilities difficult to model analytically, while the second employs simplified mechanical models adapted to each macro-type, including an equivalent single-degree-of-freedom formulation for industrial structures. The combined approach yields a harmonised classification across masonry, reinforced concrete, precast reinforced concrete and steel buildings. Its application to a large stock in Tuscany demonstrates both the operational feasibility of the method and its ability to reveal recurrent deficiencies. At the same time, the analysis highlights two critical fragilities–out-of-plane failure of infills and loss of support in precast structures–that cannot be adequately represented within rapid frameworks. Second, the thesis expands the scope to deterioration. A new methodology is proposed to classify material-specific degradation phenomena through standardised abaci and to aggregate results at project and network levels. When integrated with the seismic framework, this approach yields a combined multi-risk classification system. The introduction of new categories (F and F*) ensures that advanced or critical degradation translates into mandatory and non-deferrable retrofit actions, thereby linking the state of conservation directly to seismic decision-making. Third, the thesis addresses the fragilities identified in the seismic framework. An analytical, algorithmic plate-based model is developed for the out-of-plane capacity of masonry infill walls, validated against experimental data and Eurocode provisions, and used for parametric analyses on aspect ratio and slenderness. In parallel, a non-linear FEM-based SDOF model is implemented in OpenSees to investigate support loss in precast reinforced concrete buildings. Extensive time-history analyses under Italian ground motions validate the activation coefficient proposed in the rapid methodology and provide drift–acceleration relationships for different soil classes and friction levels. Each chapter is structured as a self-contained scientific study, yet all converge towards the same overarching aim: equipping decision makers with tools that combine operational scalability with technical rigour. The thesis demonstrates that rapid prioritisation frameworks can be significantly strengthened when integrated with degradation assessments and supported by dedicated analytical and numerical models, paving the way for more effective and informed strategies of risk reduction for large building stocks.