Abstract
The purpose of this study is the analysis of vulnerability trends, with particular emphasis to the evolution of the seismic behaviour of masonry buildings over the years due to the improvements in construction practices and to the enhancement of building materials over the years, also related to the subsequent enactment of seismic prescriptions. To this aim, residential masonry buildings damaged after the 2009 L'Aquila earthquake are considered, coming from the online platform Da.D.O. (Database di Danno Osservato, Database of Observed Damage) recently released from the Italian Department of Civil Protection. General features of all the parameters available from the original database are thoroughly analysed, a selection of which is used for vulnerability analysis, namely the period of construction and the design type, the presence of structural interventions, the type of horizontal structure. Vulnerability curves are obtained through an optimization technique, minimizing the deviation between observed and predicted damage. PGA from ShakeMap is used for ground motion characterization. Damage levels defined according to the European Macroseismic Scale are considered, obtained from the observed damage for vertical structures collected during the inspections. Vulnerability curves are firstly obtained as a function of period of construction and horizontal structural types, limited to the irregular layout and bad quality vertical type only, highlighting their clear influence on seismic behaviour. Lastly, the effectiveness of retrofit intervention is evaluated comparing the vulnerability curves for strengthened masonry buildings compared to those not subjected to any retrofit interventions.
Highlights
Masonry buildings represent a significant proportion of Italian building portfolio
The Italian DPC (Dipartimento della Protezione Civile, Department of Civil Protection), with the support of Eucentre, provided an online platform, called Da.D.O., which allows the access to a large database of buildings, collected during the visual inspections done right after the main earthquakes occurred in Italy in the last 50 years
Only L’Aquila database will be considered, with reference to residential masonry buildings, which is characterized by high numerousness, and by a substantiated reliability, i.e. an huge amount of complete sample of data, as highlighted in previous studies (Rosti et al 2018; Del Gaudio et al 2019), since it represents a fundamental requirement for fragility analysis, avoiding the propagation of biases (Rossetto et al 2013)
Summary
Masonry buildings represent a significant proportion of Italian building portfolio. A large part dates back to several decades ago, even before 1900, undergone to all environmental consequences through the years related to degradation of materials, limited by feasible maintenance works and/or retrofitting interventions. In Fiorini et al (2012) the SP-BELA procedure (Borzi et al 2008) has been used to obtain damage scenario for a subset of buildings located in the historic city centre of L’Aquila using singlebuilding data collected by Tertulliani et al (2011) All these studies do not consider the influence of design typology and retrofit intervention on observed damage. The Italian DPC (Dipartimento della Protezione Civile, Department of Civil Protection), with the support of Eucentre, provided an online platform, called Da.D.O., which allows the access to a large database of buildings, collected during the visual inspections done right after the main earthquakes occurred in Italy in the last 50 years This database, which considers the last 9 seismic events of national relevance occurred in Italy (Friuli 1976; Irpinia 1980; Abruzzo 1984; Umbria-Marche 1997; Pollino 1998; Molise 2002; Emilia 2003; L’Aquila 2009; Emilia 2012), can represent a useful support in the forecasting and mitigation policies against earthquakes. Umbria-Marche 1997 database reports a significant number of masonry buildings (similar to Abruzzo 1984 and L’Aquila 2009 databases), and a limited number of RC buildings (just 0.2% of the total)
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