Testing and design procedure for corner connections of masonry heritage buildings strengthened by metallic grouted anchors

Structural connections are crucial in determining the seismic behaviour of buildings; their importance is indeed acknowledged by current design codes, both in the case of new built and of heritage structures. Eurocode 8 in particular encourages the strengthening of connections of existing structures so as to ensure global response; yet, at the state of the art, clear prescriptions regarding the assessment of connections of heritage buildings and the design of appropriate strengthening systems are missing. Even the scientific literature seldom deals with the issue of connections, both in the unreinforced and strengthened set-up. As such, designers are left with the issue of experimentally characterise the capacity of connections, and of sourcing data and choosing suitable design procedures in order to comply with the requirements prescribed for retrofit interventions on historic buildings. In the attempt of tackling the lack of quantitative data, as well as of providing template for the experimental assessment and design of strengthening systems for connections, the authors carried out two sets of laboratory tests on masonry samples strengthened by metallic grouted anchors. Parameters significant to the performance of the connection are identified through experimental results and a design procedure is developed. The paper analyses in detail the response of a widely-applied strengthening technique, but also provides general guidance for dealing with the repair and strengthening of connections of heritage buildings.