Claudia Tiraboschi

INVESTIGATION PROCEDURES FOR THE DIAGNOSIS OF HISTORIC MASONRIES

Abstract The Friuli, Irpinia and Umbria earthquakes, and subsequent experiences, have emphasized the need for adequate damage assessment prior to seismic rehabilitation. Furthermore, assessment can be enhanced by preventive studies under the guidance of those in charge of hazard mitigation (architects, engineers, etc.). Research procedures must be defined so that findings can be used for damage assessment and as input data for structural analysis and control models. This paper provides evaluations of in-situ and laboratory tests on materials for existing unreinforced masonry structures and, in particular, touches upon the difficulty of interpreting the results of NDE tests. Also, the need for a design of the investigation prepared by persons responsible for the rehabilitation is indicated.

Application of sonic and radar tests on the piers and walls of the Cathedral of Noto

Abstract The authors applied systematically sonic tests, radar tests and other diagnostic techniques on the remaining walls and piers of the Cathedral of Noto. The experimental survey was carried out by the Laboratory of the DIS, Politecnico of Milan (Person in Charge: Prof. Binda, Prof. Baronio) in collaboration with the designers (Ing. R. De Benedictis, Arch. S. Tringali) and the experts working on the reconstruction. The Prefettura of Siracusa founded the research. The right aisle and most of the dome of the Cathedral collapsed in 1996. The aim of the research was to verify the state of damage and the possibility of conservation of the walls and piers in view of the reconstruction of the damaged part of the Cathedral. Furthermore, the sonic tests were used to control the effect of grout injection used as a possible technique for repair of the damaged masonry (Proceedings of the Conference on Nondestructive Evaluation of Civil Structures and Materials, Boulder, Colorado; (1992) 329; Proceedings of the Sixth Conference on Structural Faults and Repair, 3 (1995) 195). In the following the results will be reported and the reliability of the tests will be discussed as it was confirmed by the use of other complementary diagnosis techniques (Proceedings of the Sixth International Conference on Structural Studies, Repairs and Maintenance of Historical Buildings, STREMAH 99, Dresden, Germany, (1999) 323).

Application of sonic tests to the diagnosis of damaged and repaired structures

Abstract Sonic tests and other diagnostic techniques were systematically carried out on the existing walls of the Cathedral of Noto. The right aisle and most of the dome of the Cathedral collapsed in 1996. The aim of the research was to verify the state of damage and/or conservation of the walls and piers in view of the reconstruction of the damaged part of the Cathedral. Sonic tests were used to control the effect of grout injection used as a possible technique of repair of the damaged masonry. The results show that sonic tests can be successfully applied for the diagnosis and the effectiveness control of repair techniques.

Experimental research for the choice of adequate materials for the reconstruction of the Cathedral of Noto

Abstract Following the experimental and structural investigation the design for reconstruction was proposed. The authors were requested to test new materials, stones, mortars, grouts for injection in order to choose and proposed the material to be used for the reconstruction of the pillar and for the repair of damaged elements.

On-site investigation on the remains of the Cathedral of Noto

Abstract The Cathedral of Noto was damaged after the earthquake that hit Sicily in 1990. Soon after the event, cracks appeared on the domes of the lateral naves, and also on the pillars. In 1992 some provisional work had been carried out in view of confining the pillars of the central nave that were damaged. Some pictures made after the earthquake also show clearly the presence of moisture rise on the pillars and walls. A sudden collapse due to the damages was probably not expected, so that no other measures were taken to better strengthen and repair the structures. Only after the collapse of the Civic Tower in Pavia (1989) and the following research (Masonry Int J 6 (1992) 11, Second International Conference RILEM on Rehabilitation of Structures, Highett, Australia (1998) 542), it was clearly shown that in case of high stresses on low-strength masonry an existing damage can slowly lead to partial or total collapse of the structure over a long time. It seems a confirmation of this long-term behaviour of the structures that the Cathedral collapse took place in 1996, 6 years after the earthquake, which had certainly caused high damages to the structure.

On-site and Laboratory Investigation of Materials and Structure of a Belltower in Monza / Untersuchungen an den Werkstoffen und am Tragwerk im Labor und am Objekt am Beispiel eines Glockenturms in Monza

Abstract After the collapse of some heavy buildings and towers in Italy and elsewhere, the hypothesis of possible continuous damage to these structures due to the dead weight and cyclic loads (wind, temperature variations, etc.) has been formulated by the authors. The long term behaviour of historic masonry has also been detected by laboratory creep and cyclic tests. The results indicate that a laboratory and on site investigation together with analytical modelling are important particularly for tall bell-towers. The application of these procedures on the Bell-Tower of the Cathedral of Monza is here reported and discussed