Dynamic Test for the Model Calibration and Pier Damage Detection of an Existing R.C. Multispan Viaduct

This paper presents and discusses results of the dynamic tests performed on the Moscosi Bridge in Cingoli (Italy). The main scope of the tests is to evaluate the dynamic parameters of the bridge, such as the eigenfrequencies, the mode shapes and the relevant modal damping ratios, in order to characterize the structural behaviour before the execution of some required restoration works, providing (i) useful information for the development of the numerical model for the design and (ii) a benchmark for the evaluation of the retrofit effectiveness, by repeating tests after the retrofit. The dynamic characterization is obtained through the measurements of ambient vibrations, which are processed with the Covariance-driven Stochastic Subspace Identification. In addition, the dynamic response of the bridge subjected to a vehicle passages is registered and compared to that induced by the ambient excitations. First considerations seem to reveal the presence of the observed structural damage at the base of one pier.