TYPOLOGICAL ASPECTS, CONSTRUCTION PHASES AND STRUCTURAL BEHAVIOR OF EDGE VAULTS

The entire work is divided into three parts: the first one is aimed to identify, classify and describe construction techniques and methodologies of edge vaults used in Salento and in the area of Matera (Puglia and Basilicata districts); the second one is aimed to identify a structural behaviour model and the last one is focused to diagnose the failures that ordinarily are acertained . The first part of the work identifies and describes with plans, surveys, technical details and photos the edge vaults and, after examining the materials locally available and the originating quarries, describes and exemplifies with drawings the construction operations of various elements composing the vaults. These vaults, which we find as far back as the XVII century, are the evolution of the Gothic groin vaults. The investigation has used interviews with old master masons, last custodians of a refined artisan technique, handed down orally from father to son and destined to disappear, as there are no systematic studies. Detailed attention was given to the dialect terms, often not translatable, and to the various constructive tricks used. The study was conducted in the provinces of Brindisi, Lecce, Taranto and Matera, where this type of roofing, classified as a composed vault, is very common. Nowadays in the small municipalities of the province of Lecce it is still possible to find workers capable to build these vaults with a near perfect technique. In the second part of the paper, structural analysis of a case study consisting in a single room covered by an edge vault is performed in order to understand the structural behaviour of this traditional vault. In particular, the analysis has been performed by using the Finite Element Method (F.E.M.) through the Computer Code SAP2000. The three-dimensional F.E.M. modelling has been made by using the brick elements; both the gravity and seismic actions have been considered. The results of the structural analysis have been reported and discussed in terms of stress and deformed states and they allow us to understand the reasons of the cracking pattern that can be observed in such vault typology. In the last part of the paper, according to the typical cracking patterns occurred in 50 buildings and the restoration techniques applied, some considerations have been provided in order to understand the effectiveness of these traditional restoration interventions that mainly consist in substituting some carparo stones with C16/20 concrete. The authors believe that the results of this study could be very precious in the design practice for the diagnosis, conservation and valorisation of edge vaults. This study also proposes an avant-garde technique that, while respecting tradition, is also able to reduce or eliminate the seismic risk.