Rationale

Many historically and artistically important masonry buildings of the national architectural heritage are in dire need of maintenance and strengthening. In order to optimise such operations in terms of costs, architectural impact and static effectiveness, numerical codes able to model the structural behaviour of masonry constructions are essential. Such codes should be able to provide essential information on aspects such as the stress field, and to estimate the extent of cracking and its evolution when the structure is subjected to variations in both boundary and loading conditions, as well as to vibrations. Moreover, they should provide suitable, sound support in choosing and designing operations of strengthening and seismic retrofitting.

For over fifteen years the Mechanics of Materials and Structures Laboratory of the ISTI-CNR, in collaboration with the Department of Civil and Environmental Engineering of the University of Florence, has been studying and developing models and numerical codes for the static and dynamic analysis of masonry buildings.

In studying the structural behaviour of masonry constructions, a fundamental role is played by the choice of the constitutive equation of masonry materials, whose response to tension is different from that to compression and whose mechanical properties moreover depend on the constituent elements and building techniques used in their construction. This behaviour can be modelled by the constitutive equation of masonry-like materials, which describes masonry as a nonlinear elastic material with zero tensile strength and infinite or bounded compressive strength. This constitutive equation has been implemented in the finite element NOSA, which has allowed the Laboratory’s researchers to study the mechanical behaviour of historic buildings, and assess the stress field and crack distributions, as well as the effectiveness of strengthening operations.

The code has been successfully applied to a number of studies conducted on behalf of both private and public bodies on important historic buildings, such the chimney of the Vecchi Macelli, the Medici Arsenal and the church of San Pietro in Vinculis in Pisa, the San Nicolò Motherhouse in Noto, the Goldoni Theatre in Livorno, the Baptistery of the Volterra Cathedral, the bell tower of Buti, the church of Santa Maria Maddalena in Morano Calabro, the church of San Ponziano and the Torre delle Ore (Clock Tower) in Lucca, the church of Santa Maria della Roccella in Roccelletta di Borgia, and the Rognosa tower in San Gimignano.

NOSA-ITACA Project

The goals of the project are to develop a tool − the NOSA-ITACA code − for the structural analysis of masonry constructions of historical interest and to design an advanced service to provide training, consultancy and assistance to public and private bodies charged with safeguarding and strengthening the architectural heritage in the region of Tuscany. The project is being carried out by the Mechanics of Materials and Structures Laboratory of the ISTI-CNR and the Department of Civil and Environmental Engineering of the University of Florence.
The project has been divided into basic research, centred on studying procedure to assess the static safety and seismic vulnerability of masonry buildings, and the development of an integrated platform combining the finite element code NOSA and the open-source software SALOME, which represents the pre-post processing environment.

The NOSA-ITACA code will be used to study the “Voltone” − a large vaulted masonry structure located beneath Piazza della Repubblica in Livorno, Italy. This case study will, on the one hand, provide an opportunity to validate both the models proposed and the calculation tool developed, and, on the other, constitute a pilot project for safeguarding Italy’s cultural heritage. The approach and methods used to study the “Voltone” can in fact be applied to other similar structures.

The results of the project will find application in the field of Cultural Heritage, to support the activities of safeguarding and strengthening historic masonry constructions. Finally, a technical support service, based on the NOSA-ITACA code, will provide consultancy, assistance and training to municipalities, monuments and fine arts institutions and professionals, to aid them in maintaining and safeguarding historical masonry buildings and monuments. This technical support service will also be responsible for managing and upgrading the software.

Applications of the NOSA-ITACA code

The Voltone, piazza della Repubblica, Livorno

The “Voltone” (i.e., the great vault) is a 220-meter long masonry structure located beneath Piazza della Repubblica in Livorno. It is constituted by a segmental vault, through which the “Fosso Reale” canal flows. The vault is set on two lateral walls and strengthened by buttresses placed at intervals of about 5 meters one from the other.(more details)

Church of San Francesco, Lucca

The church of San Francesco, dating back to the 13th century, is a typical Franciscan masonry building with one nave, about 70 m long, 16 m wide and 19 m high. The nave is closed on the west by the façade overlooking the square of San Francesco and on the east by the apse. The northern wall leans against the portico of the monastery cloister; the southern wall, completely free, runs along the street named via della Quarquonia.(more details)

Cathedral of San Cerbone, Massa Marittima (GR)

The NOSA-ITACA code has been used to model the static conditions of the dome of the San Cerbone Cathedral. The study has been carried out within the framework of the research project “Structural assessment and evaluation of the seismic vulnerability of San Cerbone Cathedral in Massa Marittima (Grosseto), aimed at identifying the need for reinforcement operations”.

The project, conducted by Anna De Falco of the University of Pisa and funded by the Diocese of Massa Marittima and Piombino, aimed to identify the origins of the widespread fracturing occurring on the dome and to simulate some restoration operations.(more details)