Development of a new seismic vulnerability model for churches based on simple typological features

Abstract

The sequence of seismic events occurred in last decades in Italy highlighted the high vulnerability of churches. Since the Umbria–Marche earthquake in 1997, a systematic series of post-earthquake surveys has been carried out. The data collected during those surveys were used to propose first sets of vulnerability and fragility curves. After the three last major earthquakes (L’Aquila 2009, Emilia 2012, Central Italy 2016–2017), other significant series of on-site surveys led to the collection of a large amount of data, both on the damage suffered by churches and their typological characteristics. In this study, a data set of 1127 churches damaged by the 2009 L’Aquila earthquake and the 2016–2017 Central Italy seismic sequence was analyzed. This article presents a new simplified approach to determine vulnerability indexes of churches, in order to obtain vulnerability curves, and then a set of fragility curves, depending on the typological characteristics of the single church. This allows to have a single set of curves with the entire sample and without a typological subdivision. This article first analyzes in detail the available database records to define their representativeness and influence on vulnerability. Then, a series of vulnerability modifiers are defined, pointing out which parameters effectively affect the overall vulnerability. These observations also allow identifying which parameters deserve to be collected onsite, improving the efficiency of future survey campaigns. In conclusion, starting from the vulnerability modifiers, a set of vulnerability and fragility curves are presented.