Issue 30

F. Felli et alii, Frattura ed Integrità Strutturale, 30 (2014) 48-54; DOI: 10.3221/IGF-ESIS.30.07 48 Focussed on: Fracture and Structural Integrity related Issues Use of FBG sensors for monitoring cracks of the equestrian statue of Bartolomeo Colleoni in Venice F. Felli, A. Brotzu, D. Pilone, C. Vendittozzi Dip. ICMA, Sapienza Università di Roma, Via Eudossiana 18, 00184 Roma, Italy ferdinando.felli@uniroma1.it M.Caponero ENEA Via E. Fermi 45, 00044 Frascati, Roma A BSTRACT . The Bartolomeo Colleoni monument suffered for years damage from the local climate. The process of restoring the Colleoni equestrian statue, started in 2003, allowed to understand how the bronze statue was originally cast and manufactured and the techniques used in its construction. During this process a relevant crack on the right foreleg was investigated in correspondence of the cast-on joining the right foreleg to the front portion of the horse body. The crack was investigated experimentally by Fiber Bragg Grating (FBG) sensors, avoiding any modelling because of the very complex structure of the statue. An array of FBG sensors connected in series was glued on the crack with the aim of capturing live information about the effect of applying stress on the crack opening. The monitoring system was successfully tested during repositioning of the RIDER on the horse and is available for long term inspection of the crack opening evolution. K EYWORDS . FBG sensors; Health monitoring; Crack monitoring; Restoration; Colleoni equestrian statue. I NTRODUCTION he Bartolomeo Colleoni equestrian statue, located beside the Scuola Grande di San Marco in the Campo SS Giovanni e Paolo, was erected in fulfillment of a request made by the mercenary captain before his death in 1475. After switching allegiances several times, in 1457 he was endowed with supreme command of the Venetian army by the doge of Venice. Shortly before his death, Colleoni bequeathed a sizable portion of his estate to the Republic of Venice, with the stipulation that a bronze equestrian monument should be erected in the Piazza San Marco to perpetuate his memory. The Venetian Senate honored his request but placed the statue near the Scuola Grande di San Marco rather than in Piazza San Marco. Andrea del Verrocchio won the commission for the Colleoni statue in a competition. Contests for public art commissions were frequent in fifteenth-century Italy. In fact, sponsors hoped to obtain not only the best, but also the most efficient designs. The Bartolomeo Colleoni Monument is among the best-known works of Verrocchio, that was a teacher of Leonardo da Vinci. Verrocchio died in 1488, before finishing the work, and the statue was finished by Alessandro Leopardi in 1495. T