Experimental assessment of the expected impact of a bridge seismic retrofit through ambient vibration tests

This paper presents and discusses results of ambient vibration tests performed on the Moscosi Bridge in Cingoli (Italy) before and after the execution of seismic retrofitting works. The aim of the first 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 build up a numerical model and, through it, to predict the behaviour of the bridge after the interventions. The dynamic characterization of the bridge is obtained through the measurements of ambient vibrations, which are processed with the Covariance-driven Stochastic Subspace Identification. The information derived by the calibrated model are compared with the results of a second ambient vibrational measurement campaign, and the effectiveness of the retrofit is assessed.