An approach for the mechanical characterisation of the Asinelli Tower (Bologna) in presence of insufficient experimental data

The Asinelli Tower, built at the end of the 12th century, is one of the main symbol of the town of Bologna and a valuable historical heritage of the Medieval age of the entire Italy. For its structural configuration, the tower appears prone to seismic damages and, therefore, an assessment of its dynamic properties is of primary importance to predict its seismic response. In the present paper, based on the results of limited material tests, the mechanical and dynamic properties of the tower are analysed through the development of models of increasing complexity. First, models for the evaluation of the main materials mechanical properties are compared to validate the experimental results. Then, different structural models of the tower (from simple continuum analytical models to more complex finite element models) are developed. The analytical and numerical results obtained from the different models are finally compared to some recent experimental measurements of the free vibration response of the tower conducted by the Italian National Institute of Geophysics and Volcanology (the INGV). The preliminary results indicate that the experimental frequencies are in good agreement with the values obtained from the models. However, additional studies are necessary to better understand the torsional response of the tower.