Influence of Retrofitting by Clamps on the Behaviour of Dry Stone Historical Masonry Structures Under Seismic Load

Dry stone structures, especially in the Mediterranean area, are often represented as cultural heritage buildings. The strategic goal is to preserve significant structures; therefore, it is necessary to know as well as possible what their behaviour is as a result of the expected actions. On the basis of this, appropriate decisions can be made in case of necessary retrofitting. One of the most destructive actions on structures is an earthquake. Therefore, this paper assessed the behaviour of three dry stone historical structures under seismic loading in the historic centre of the city of Split in Croatia. The bell tower of St. Domnius Cathedral, the Eastern colonnade, and the Prothyron in Diocletian’s Palace were analysed. The presented numerical analyses were processed using the Y-2D computer programme, based on the combined finite-discrete element method. The structures were modelled with plane models in which stone blocks were modelled as discrete elements. This numerical model, in addition to allowing the estimation of seismic resistance, provides a very realistic expected failure mechanism, which is its significant advantage. Namely, this information is crucial for determining appropriate measures in case structural repairs become necessary for these types of structures. In the framework of this paper, this is exactly what was used to determine the place where the structure needs to be strengthened. By incrementally increasing the ground acceleration, the seismic resistance of the structures with the original geometry for all three earthquakes were first analysed. After the mode of the failure mechanism was obtained, structures were strengthened with clamps and the influence of retrofitting on the seismic resistance and failure mechanism was analysed for the case of the most unfavourable earthquake load.