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Structural diagnostics and monitoring of cultural heritage

Keywords: historic structures, marble statues, NDT, cracks, sensors, monitoring
Fig. 1. Modena Cathedral, Palazzina della Viola, Palazzo D’Accursio, San Barbaziano church (top); Palazzo Malvezzi (bottom) (Colla).
Fig. 2. David and Prigione Barbuto at the Galleria dell’Accademia in Florence (Pascale).
Structural diagnostics and monitoring of cultural heritage - Fig. 3
Fig. 3. Ultrasound tests at the David and wireless monitoring of salt content in masonry (Colla).

The Cultural Heritage evaluation requires a multiphase and integrated diagnostic approach with extended and deepened experimental campaigns, not harmful to the object. The research group works on the development and use of advanced non-destructive and minimally invasive survey techniques, test procedures aimed at determining the health-state of historic structures and their materials (brick and stone masonry, mortar, timber). Among these, sonic tests, ultrasonics, radar, IR thermography, tomography, penetrometric tests on mortar and timber, microcoring, lab determinations on historic samples. In addition, structural monitoring, both traditional and wireless, has been carried out. The developed testing procedures have been implemented on historic buildings together with onsite load tests or image correlation monitoring (Fig. 1). The experience gained has resulted in prestigious projects in the field of Cultural Heritage, such as the 7FP EU Project SMooHS, the agreements with regional architectonic and archaeological Superintendents and with the Galleria dell'Accademia in Florence, for monitoring large marble statues including two Michelangelo Buonarroti works: the famous David and the “Prigione Barbuto”. In large marble statues, the large masses and shapes often cause high stresses in the material, especially in case of earthquakes or other vibrations. This can result in dangerous situations. Thus, non-destructive diagnostic investigations and continuous monitoring by means of minimally invasive, high sensitive and stable systems, able to give early warnings, become necessary. The David presents a severe crack pattern in the lower part of the legs. The cracks’ depths estimation, important for the structural analyses, has been carried out by means of ultrasonic tests, using properly developed and optimized procedures. A wide crack in the “Prigione Barbuto” has been monitored over two years with laser triangulation sensors. The crack pattern of the David is monitored by a fiberoptic sensors FBG network, providing remotely recorded and processed information. The system is controlled by a device which also measures vibration, inclination and changes in the environmental parameters.

Main publications

Colla, C., (2016) On-site diagnosis of masonry structures via sonic tomography: the case of the ex-church of S. Barbaziano, IBMAC 2016, Modena, da Porto & Valluzzi (Eds), 1507-13, Taylor & Francis, London.

Colla, C., Ji, X., Pascale. G. (2015), “High definition NDT investigation of large statue pedestal”, AIPND 2015, 16° Nat. Conf. Non-destructive tests, Monitoring and Diagnosis, Milano, Italy, 21-23 Oct. 2015, IDN31, 10 pp.

Baraccani, S., Palermo, M., Silvestri, S., Gasparini, G., and Trombetti, T. (2015) “SSHM and DSHM for a better knowledge and risk prevention of historical buildings: The cases of the Two Towers in Bologna and the Cathedral in Modena”, IEEE Workshop on Environmental, Energy and Structural Monitoring Systems (EESMS), pp. 180-185.

Colla, C., Gabrielli, E. (2015) “On-site integrated non-destructive diagnosis of historic timber elements: the case of the roof of Palazzo D’Accursio, Bologna”, SHATIS 2015, 3rd Int. Conf. on Structural Health Assessment of Timber Structures, Wroclaw, Poland, Sept. 9-11, 2015, Jerzy Jasieńko & Tomasz Nowak (Eds), 2015 DWE, Wrocław, Poland, ISSN 0860-2395, ISBN 978-83-7125-255-6, vol. 1, pp. 479 – 490.

Colla, C., Pascale, G., (2015), “Diagnostics and monitoring of the church of S. Barbaziano in Bologna”, Key Engineering Materials 624, Chapter 2: Masonry, 147-154.

Colla, C., (2015), “In situ investigation of the mechanical strength of mortars: the case of the vaults of Modena cathedral”, Key Engineering Materials 624, Chapter 2: Masonry, 170-177.

Gabrielli E., Colla, C., (2015), “Investigation of damp and salt distribution in outdoors full-scale masonry wall via wireless monitoring and radar testing”, Key Eng. Mat. 624, Chapter 2: Masonry, 155-162.

Gentilini, C., Marzani, A., Mazzotti, M. (2013) Nondestructive characterization of tie-rods by means of dynamic testing, added masses and genetic algorithms, Journal of Sound and Vibration, 332, 76-101.

Pascale G., Lolli A., “Cracking assessment in the David by Michelangelo”, 5th Int. Conf. NDT of HSNT - IC MINDT 2013, Athens, Greece, May 20-22, 2013.

Colla C., Gabrielli E., Pascale G., Di Tommaso A., Ubertini F., “Masonry assessment for the seismic risk evaluation of historic structures”, 15th IB2MaC, 15th Int. Brick and Block Masonry Conf., Florianópolis, Brazil, June 3th-6th, 2012.

Colla, C., et al., “Integrated approach for on-site assessment of conservation state of a historical masonry building: Malvezzi Palace, Italy”, SAHC 2012, Structural Analysis of Historical Constructions, Wroclaw, Poland, Oct. 15th -17th, 2012, ISBN 978-83-7125-216-7, pp. 2367–2375.

Colla, C., Gabrielli, E., Krueger, M., Lehmann, F., Bastianini, F., “On-site loading test in the historic building of Malvezzi Palace, Bologna, Italy: experience integrating traditional measurements tools with wireless sensor systems”, EWCHP 2012, Kjeller, Sept.24th-26th, 2012, ISBN 978- 82-425-2525-3, pp. 198-206.

Research projects

SARISTU - Smart Intelligent Aircraft Structures, FP7-2011, Collaborative EU project. Project Ref: 284562.

SMooHS – Smart Monitoring of Historical Structures, FP7-2008, Collaborative EU project. Project Ref.: 212939.

Convenzione con Fondaz. “Friends of Florence” per monitoraggio dello stato fessurativo presente nel David di Michelangelo presso Galleria dell’Accademia di Firenze, delle vibrazioni alla base e di altri parametri correlabili alla situazione statica dell’opera d’arte, 2009-2011.

Convenzione con Comune di Modena per campagna di indagine sperimentale presso l’edificio storico con struttura portante di muratura di laterizi ed esterno in conci lapidei denominato “Torre Ghirlandina”, a Modena, a seguito del sisma del 20-29 maggio 2012 (2013).