Seismic Behaviour Analysis of Diaphragm Arches: Case Studies from Catalan Gothic Churches

The Gothic style spread, starting from the 12th century, from the Ile-de-France to England and other countries of the Mediterranean area, such as Spain and Italy, according to different configurations and construction techniques, influenced by economic, environmental and social factors. The so-called Catalan Gothic style is not exclusive to the architecture of the Principality of Catalonia but extends to the territories of the Crown of Aragon and Southern France. Its most important characteristics, based on the unitary conception of space and horizontality, had the religious architecture as their major reference. Among other structural elements, the large use of diaphragm arches, built transversally to the longitudinal direction of the nave, has been identified as peculiar both in ecclesiastic and civil Catalan Gothic architecture, although this technique is widely diffused also in the rest of the Mediterranean Europe. The present study focuses on the behaviour of this construction system under horizontal loads. After some brief notes on the history, origins and evolution of diaphragm arches, preliminary outcomes obtained by means of seismic analyses are provided in this paper. In particular, the possible collapse mechanisms of such remarkable curved structures have been firstly investigated by implementing FEM Models derived from real Catalan examples. Therefore, seismic analyses by means of analytical models have been carried out on the detected cases in order to demonstrate the capacity of this kind of structural skeleton, the importance of geometric ratios and the influence that specific typical elements may have in modifying the seismic behaviour of the analysed structures.