Extracting cores with diameters of 100 to 150 mm from masonry structures has emerged as a novel, less destructive method for assessing the mechanical properties of masonry units, particularly their compressive strength. Unlike traditional methods, such as using larger wallets, this approach requires less material and causes minimal damage to the original structure, which is critical when dealing with historical buildings. However, to obtain consistent and reliable results, certain parameters, specifically the dimensions of the core cap, must be carefully defined, as they significantly influence the overall behaviour of the samples. The study employs a detailed block-based modelling approach, incorporating zero-thickness cohesive elements at the brick-mortar interfaces. Additionally, tangential and normal contact interactions were defined between the cap and core components. The concrete damage plasticity (CDP) model, implemented in ABAQUS, has been adopted as the constitutive model to account for the nonlinear behaviour of brick, mortar, and cap. The results indicate that the length of the cap has a more pronounced effect on the sample’s mechanical behaviour than its height. Additionally, the study investigates the mechanical properties of the interface between the cap and the core, identifying friction and normal stiffness as critical factors. These findings provide valuable insights for optimizing the core capping process and improving the reliability of masonry mechanical property assessments, particularly in the preservation of historical structures.

The lack of effective connection between masonry walls is one of the most common reasons leading to the activation of out-of-plane failure mechanisms in masonry buildings during earthquakes. Thus, retrofitting interventions aimed at improving the box-like behavior of masonry structures are of primary importance. The paper presents the results of an experimental program aimed at investigating the effectiveness of two different fastening solutions to improve the joint connection of masonry walls in existing unreinforced masonry buildings. A full scale C-shaped clay brick masonry specimen was built featuring purposely weakened wall intersections. Vertical prestress was applied on top of the specimen to represent the weights of upper floors. The specimen was first tested in the unreinforced configuration under monotonic out-of-plane displacement, until a main crack was detected. Then, its corner connections were repaired using twisted bars, and tested under cyclic out-of-plane displacement. Lastly, the twisted bars were removed and replaced with bonded bars, and the specimen was tested again under cyclic out-of-plane displacement. The test results showed that both retrofitting solutions were able to recover the full capacity of the unreinforced wall, with higher displacement and dissipation capacity for the twisted bars solution, and higher resistance for bonded bars. The latter seems to be the most effective solution, especially in terms of monolithic behavior achieved; however, the large displacements associated to twisted bars could be a great advantage in case of earthquake actions.

Steel reinforced plasters (SRP) are a traditional strengthening solution of existing masonry structures. SRPs consist of a thin layer of cementitious mortar or concrete (jacket) that incorporates a steel reinforcing mesh tied to a series of steel bent connectors embedded in the underlying masonry. Despite the recent development of more innovative retrofitting methods, SRPs are still widely adopted because of their low costs and effectiveness in terms of improved performance. In the present paper, a comprehensive experimental program on brickwork masonry walls is presented. The results are intended as a contribution to the knowledge of in-plane behavior of masonry strengthened with SRPs. Unreinforced and plastered masonry walls were subjected to cyclic diagonal compression loading under displacement control. Different thicknesses of walls (2 and 3 wythes) and plasters (30 and 50 mm) were selected. The performances of the plastered and non-plastered specimens were analyzed and compared. The results showed that the SRPs increased considerably the performance of the walls in terms of both strength and deformation capacity. The plaster's thickness had limited effects on the load carrying capacity of the walls, whereas it had a significant effect on their ductility. Finally, the connectors used to tie the steel mesh to the masonry walls played an essential role and avoided large out-of-plane displacements of the plaster layer after its detachment, thus preventing instability phenomena.

In Europe, the qualification of injection anchors in masonry under static and quasi-static actions is based on an assessment of tests performed in undamaged masonry. Nevertheless, in seismic prone countries like Italy the influences deriving from earthquake actions cannot be disregarded. Masonry elements are very sensitive to cyclic/seismic action and research on the behavior of anchors in damaged masonry is rather limited. The paper presents the results of an experimental campaign aimed at evaluating the residual tensile strength of adhesive anchors installed into undamaged walls that were subsequently subjected to cyclic in-plane loading to simulate seismic actions before. Consequently, the anchors experienced different stresses depending on their location within the walls. Overall, 29 tests were performed with anchors placed both, in undamaged and damaged areas. The results showed that there is a correlation between residual tensile strength and masonry initial conditions, and therefore the installation of anchors in masonry elements should be carefully planned avoiding areas that could be heavily damaged during seismic events or considering redundant connections in critical areas. In particular, it seems that the width of the crack (created by cyclic actions) that passes nearby/into the anchor borehole is the main parameter that affects the ultimate resistance of the anchors.