Wavelet Based Approach to Structural Dynamic Identification: the Case of the Main Vara Viaduct

This paper investigates assessing and monitoring historical masonry structures reliability via experimental modal analysis techniques. The dynamic behaviour of a five span arch bridge, the main Vara Viaduct inside Carrara’s marble’s caves in Italy is studied. The paper describes the preliminary numerical studies and the experimental tests carried out in 2002 and 2006. In particular it focuses on the problems connected with modal parameters identification when structural response is low amplitude and embedded in noise. An innovative wavelet based approach for signal processing is investigated. The results achieved show that wavelet transformation performs better than classical Fourier analysis when time histories are contaminated by noise. A structural non linearity is also identified through the variation of resonant frequencies and damping coefficients with the amplitude of oscillation.