Seismic risk assessment at the territorial level is now widely recognised as essential for countries with intense seismic activity, such as Italy. Academia is called to give its contribution in order to synergically deepen the knowledge about the various components of this risk, starting from the complex evaluation of vulnerability of the built heritage. In line with this, a mechanics-based seismic fragility model for Italian residential masonry buildings was developed and presented in this paper. This model is based on the classification of the building stock in macro-typologies, defined by age of construction and number of storeys, which being information available at national level, allow simulating damage scenarios and carrying out risk analyses on a territorial scale. The model is developed on the fragility of over 500 buildings, sampled according to national representativeness criteria and analysed through the Vulnus_4.0 software. The calculated fragility functions were extended on the basis of a reference model available in the literature, which provides generic fragilities for the EMS98 vulnerability classes, thus obtaining a fragility model defined on the five EMS98 damage states. Lastly, to assess the reliability of the proposed model, this was used to simulate damage scenarios due to the 2009 L’Aquila earthquake. Overall, the comparison between model results and observed damage showed a good fit, proving the model effectiveness.

More than the 60% of the Italian residential building stock had already been built by 1974, when seismic codes were enforced on a minimal part of the country. Unreinforced masonry buildings represent most of that share, but they are typical for each region, in terms of both materials and structural configurations. The definition of ‘regional’, i.e., more specific, vulnerability and exposure models are required to improve existing forecast models. The research presents a new geographic information system (GIS)-based multilevel procedure for earthquake disaster prevention planning at urban scale; it includes multicriteria analysis, such as architectural types, structural vulnerability analysis, microzonation studies, and socio-economic aspects. The procedure has been applied to the municipality of Pordenone (PN), a district town of the Friuli–Venezia–Giulia region, in Northeast Italy. To assess the urban seismic risk, more than 5000 masonry residential buildings were investigated and common types within sub-municipal areas and exposure data were collected. Simplified mechanical analysis provided a ‘regional’ vulnerability model through typological fragility curves. The integration of results into GIS tool permitted the definition of cross-mapping among vulnerability, damage scenarios (conditional and unconditional) and exposure (seismic losses, casualties, impact), with respect to various earthquake intensities expected in the town. These results are presented at different scales: from the single building, to submunicipal area and to the entire town.

Seismic events that have occurred in Italy in recent decades have shown the significant vulnerability of the Italian building stock. In particular, residential masonry buildings have suffered serious damage, highlighting the need to plan effective mitigation strategies as soon as possible. In this context, this study aims to evaluate the effectiveness of possible retrofit interventions for masonry buildings. Fragility curves of macro-classes of residential masonry buildings have been developed in both as-built and retrofitted conditions within the DPC-ReLUIS agreement (Department of Civil Protection—Network of University Laboratories for Earthquake Engineering). In particular, three sets of fragility curves, developed by the University of Padova (UniPD) and the University of Genova (UniGEa and UniGEb) are discussed and compared herein. The three models show similar estimates of the expected structural improvements for the examined retrofit interventions when applied to the building macro-classes, although some differences, due to the different analysis approaches, can be observed.

Masonry is a widespread construction system, but it is very prone to seismic damage. In Italy, almost 60% of residential buildings are constructed in masonry, and 85% of them were built before 1980 without specific design regulation; thus, there is the need for large-scale vulnerability assessment. When large stocks of residential buildings (>50–100) are involved, also in historical centers, seismic vulnerability analysis must resort to simplified and computer-aided methods. Among these, the best known analyze (i) the overall shear strength normalized to the weight; (ii) the activation coefficient of local mechanisms; and (iii) dimensionless indexes obtained from the weighted sum of scores associated with a set of vulnerability factors. The Vulnus procedure proposes a vulnerability function in the 3D space defined by these factors, namely V_IP, V_OP and V_V. The ‘mechanical’ indexes V_IP and V_OP determine the capacity of the building (in-plane and out-of-plane, respectively), whereas the ‘empirical’ index V_V sets the pace at which this capacity is reached and the uncertainty in its final value. The procedure considers the confidence level of the indexes by means of fuzzy set theory, which enables expression of the vulnerability in linguistic terms (e.g., ‘high’ or ‘low’), as well as through a fragility curve. In this paper, a web toolbox based on the Vulnus procedure, namely, Vulnus Web, is proposed. It enables the central archiving of data, improved interaction with the program code and a wider dissemination. The new procedure was applied to a masonry building hit by the Central Italy 2016 earthquake; both the vulnerability level assessed numerically and the damage prediction were in good accordance with the actual seismic performance of the building.