Dynamic testing on the new ticino bridge of the A4 highway

The dynamic tests on the two separate viaducts constituting the bridge over the Ticino river offered the chance to start a thorough identification process consisting in numerical simulation, experimental activity and model updating, to gather a deeper knowledge of the bridge behavior. In addition, this series of tests has offered a good benchmark to prove the actual strengths and weaknesses of the Italian standards for dynamic testing. The two viaducts are identical and made up of a series of equal length spans, making modal identification a more complex task, since it has to be performed in the presence of dense spectra with a number of closely spaced peaks, belonging to quite similar mode shapes. Operational Modal Analysis (OMA) was performed and is scheduled to be repeated in the future to assess any eventual on-going damage. The paper will present the results of the experimental activity compared to the numerical predictions and the model tuning activity.