The crucial need to reduce the socio-economic consequences and impacts of earthquake events through the implementation of seismic risk reduction strategies at national level has been further emphasized by the recent catastrophic earthquakes (e.g., L'Aquila 2009; Emilia 2012; Central Italy 2016). A fundamental step towards the implementation of a medium-to-long-term national plan of seismic risk reduction consists of the definition of a prioritization plan at national scale, based on a detailed seismic (vulnerability) assessment (DSA) of the built environment in terms of both life-safety and expected economic losses. However, the evident complexity in the data acquisition of the building stock, as well as the need for improved and standardized tools and procedures for seismic vulnerability analysis of existing buildings are often deemed as primary obstacles to the implementation of such an ambitious plan.

To overcome this issue, and as part of a wider research project, this paper presents and discusses the ongoing developments regarding the definition of a multi-knowledge level seismic assessment procedure for large-scale seismic risk applications. The procedure involves the analytical-mechanical SLaMA (Simple Lateral Mechanism Analysis) method and allows for an adaptive and updatable assessment of the seismic performance of buildings accounting for different data acquisition (knowledge) levels. By coupling this approach with vulnerability assessment survey forms, a range/domain of expected capacity curves of the structure can be obtained and used to evaluate the seismic safety and the expected economic losses according to the state-of-the-art procedures in literature. Moreover, the results of the analytical assessment method can be used to develop fragility curves through simplified spectrum-based procedures. Combining the results of the fragility analysis with the hazard analysis, the seismic risk of the structure can be assessed in terms of Mean Annual Frequency (MAF) of exceeding a specific Damage State (DS), useful parameter to develop national seismic risk maps. The procedure is illustrated for a reinforced concrete case-study building, designed for gravity loads only. Results confirm the effectiveness of the proposed methodology for seismic-risk assessment studies at large scale, thus overcoming the issue related to limited building information, yet allowing for a continuous update of the "digital twin" model and thus of the seismic risk assessment outcomes as further data/information becomes available, and supporting the definition of a prioritization plan.