An Overview of the Historical Retrofitting Interventions on Churches in Central Italy

The seismic sequence occurring in Central Italy in 2016 represents a new test benchmark for historical masonry churches and a chance for a better comprehension of their structural behavior under earthquake actions. The many earthquakes that took place in the past have led to stratifications of repair and retrofitting interventions that sometimes worsened the structural behavior, especially when resulting in the introduction of elements not compatible with the churches' original layout. Within this framework, the present paper intends to provide a critical review of the main interventions carried out in the churches of Central Italy for mitigating their seismic vulnerability and to evaluate their effectiveness in light of the damage surveyed on a representative sample of masonry churches after the 2016-2017 seismic sequence. The work is organized into three parts: (1) historical analysis of the territory; (2) review of the featured interventions; (3) critical appraisal of the interventions in relation to the surveyed data and assessment of their effectiveness. The goal of the work is to shed light on the correct design of retrofitting interventions in ancient masonry structures in order to enhance the structural safety of such artefacts without compromising their historical and cultural value.