Seismic and Energy Retrofitting of Unreinforced Masonry Building Aggregates: A Case Study in Visso Affected by 2016 Earthquake

Seismic events in Italy and other regions with high seismicity—such as Turkey, Morocco, and Greece—have underscored the significant vulnerability of existing unreinforced masonry buildings. These structures are often grouped together, forming multiple adjacent units that are not always properly interconnected. Factors contributing to their fragility include poor maintenance, advanced age, the use of materials with low mechanical performance, and the absence of seismic design considerations. Collectively, these issues exacerbate the vulnerability of this valuable architectural heritage. This study investigates a masonry building aggregate composed of five structurally connected units arranged linearly in the municipality of Visso, located in the Macerata district—a region severely affected by the 2016 earthquake. Numerical methods are employed to assess the building’s seismic behaviour. Static non-linear and dynamic linear analyses reveal the structure’s inadequacy under seismic loads. In response to these findings, the paper proposes an innovative retrofitting solution aimed at improving both seismic resistance and energy efficiency. The solution involves the installation of external metal exoskeletons made from AW6060 aluminium alloy, chosen for its lightweight properties and sustainability. In addition, thermal insulating panels are integrated to minimize heat loss through the building envelope. The study concludes with a mechanical-based fragility analysis, which demonstrates the effectiveness of the proposed integrated external coating system in enhancing the structural performance of the examined clustered building.