Seismic Vulnerability of Masonry Arch Bridges: Case Studies from Avellino Province

Bridges are essential components of transportation infrastructure. Among them, masonry arch bridges warrant particular attention due to their widespread presence in both European and national heritage, as well as their historical and structural significance. This study forms part of the activities carried out under the ACaMIR–ReLUIS research project, which focuses on the application of the Guidelines for the classification, risk management, safety assessment, and monitoring of existing bridges. The research examined a sample of fourteen bridges located in the province of Avellino, Italy, with particular focus on a subset of masonry arch bridges, the most prevalent typology in the dataset. To evaluate their seismic vulnerability, the Seismic Attention Class was determined in accordance with the procedure outlined in the Guidelines. This classification served as a basis for establishing a preliminary intervention priority among the selected bridges. The analysis was further refined through the calculation of a seismic risk index for each structure. Among the six masonry arch bridges analyzed, only one achieved a positive result, highlighting the critical condition of the existing infrastructure and reinforcing the urgent need for targeted conservation and seismic mitigation measures.