Analytical formulation for the design of steel reinforced plaster

Among the available techniques to improve the performance of existing masonry structures, steel reinforced plaster (SRP) is largely adopted to retrofit common residential masonry buildings. The adoption of the method is mainly due to its simple technology, which recurs to ordinary and cheap materials, associated with its high effectiveness. Even if several technical codes suggest it as a possible retrofitting intervention for existing masonry, satisfactory theoretical models to be used for the practical design are not available in the scientific literature. This paper proposes an analytical method to predict the strength of SRP-retrofitted masonry walls. The aim is to define a general design formulation, which considers the main parameters that affect the performance of the strengthened wall (e.g., thickness and mechanical properties of the plaster, number of connectors), to be used in daily structural engineering practice. The method was developed starting from a database of experimental results of diagonal compression tests conducted on unreinforced and retrofitted masonry specimens. The proposed formulation is able to approximate the experimental values with an acceptable level of accuracy, being on the safe side in most of the cases. It should be noticed that the experimental data used in the assessment process were limited to specific masonry types. For this reason, further experimental results should be acquired to extend the validity of the proposed method to other masonry base materials and confirm the good trend of the prediction model.