Mechanics-based fragility curves for Italian residential URM buildings

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

Strategies for Structural and Energy Improvement in Mid-Rise Unreinforced Masonry Apartment Buildings. A Case Study in Mestre (Northeast Italy)

Two-thirds of the Italian building stock was already built by the 1970s, largely according to gravity load design and using economical materials and poor workmanship. Currently, the structures, fixtures, and fittings of these buildings have reached the end of their service life, and they require both an assessment and an update to meet new standards and new needs. As an example of a common type, this article deals with the assessment of the present state and the proposal of an integrated structural and architectural intervention on an existing brick masonry mid-rise apartment building in the suburbs of Venice, Northern Italy. The structural analysis highlights a moderate vulnerability, despite the low seismic hazard, and the energy analysis indicates that the highest management costs are due to heating and sanitary uses. Low-impact strategies are preferred for each aspect of the required interventions. Their costs are counterbalanced by (a) the reduction to a fifth of the present management costs; (b) a 20% average increase in the economic value of the flats; and (c) a favorable tax regime at the national level. Transformed into parametric values, also useful for large scale analyses, these costs resulted in a sustainable monthly instalment from the owners, who may also benefit from the increased quality of the place where they live

A New Methodology for the Survey and Evaluation of Seismic Damage and Vulnerability Entailed by Structural Interventions on Masonry Buildings: Validation on the Town of Castelsantangelo sul Nera (MC), Italy

Damage surveys following to the Central Italy 2016 seismic swarm have shown that retrofitting or strengthening interventions on masonry buildings may result in unexpected seismic behaviour, which may be defined as hybrid. In fact, the insertion within the masonry of single parts aimed at activating the box-like behaviour can worsen the overall response like a vulnerability added to a building’s intrinsic ones. Existing procedures for post-earthquake visual assessment do not permit the definition of the behaviour of altered masonry buildings (substitution of horizontal structures, concrete curbs, injections, etc.). The article proposes a completion of the ‘knowledge path’ of an existing survey form adding a new part specifically dedicated to structural interventions. On-site data collection is performed by a digital survey form written in Google Forms. The analysis phase takes advantage of the features available in a Geographical Information System (GIS). The application of this survey form to about one hundred buildings in Castelsantangelo sul Nera (Macerata district, Central Italy) hit by the Oct. 26 and 30, 2016 quakes also helped to define the vulnerability classes for buildings with structural interventions. Empirical results show that either poor execution or conception of interventions can lead to the highest vulnerability classes

Mechanics-based fragility curves for Italian residential URM buildings

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 theVulnus_4.0software. 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

The spread of SARS-CoV-2 at school through the different pandemic waves: a population-based study in Italy

Proactive school closures are often considered an effective strategy by policy-makers and the public to limit SARS-CoV-2 transmission. While evidence on the role of students in the spread is debated, the effects of closures on children's well-being are well known. In the light of this, we aimed to assess viral spread in educational settings, by calculating the rate of secondary infections per school class and identifying factors associated with cluster generation. We conducted a combined longitudinal and cross-sectional population-based study between October 2020 and November 2021. Secondary screening was conducted whenever a SARS-CoV-2 positive subject had been in the school environment in 48 h prior to symptoms onset or on the date of swab, if asymptomatic. The effect of selected variables on COVID-19 cluster generation was assessed by logistic regression. We identified 1623 primary COVID-19 cases. Of these, 72.5% resulted in no secondary case, 15.6% in 1, and 11.9% in 2 + . The probability of generating a 2 + cluster was lower when the index case was a student, rather than school staff (AOR = 0.42; 95%CI: 0.29-0.60). The number of clusters per week was in line with COVID-19 incidence trend in the general population