Seismic risk reduction of masonry barrel vaults using CRM: fragility assessment using a fiber-section approach

Masonry barrel vaults made of calcarenite natural stone are widespread in the built heritage of the Mediterranean area. Post earthquake observations have highlighted their vulnerability under seismic loads especially when they are used as secondary elements carrying their own weight only. This study explores the effectiveness of seismic risk reduction for calcarenite masonry barrel vaults using cementitious reinforced mortar (CRM) in the extrados combined with Glass Fiber Reinforced Polymer (GRFP) grids. A force-based fiber-section beam/column model is implemented to effectively capturing axial force–bending moment interaction while reducing computational costs. Multiple-stripe analyses are carried out for different configurations of the case study based on a real calcarenite masonry barrel vault. The results show that CRM retrofitting can increase displacement capacity and shift fragility curves to higher intensities, with spectral accelerations at 50% collapse probability from two to six times greater than the as-built condition. The influence of additional boundary conditions such as the presence of backfill material and the premature debonding of the reinforcement are also investigated.