Sensitivity Analysis on the FE Model Parameters of the Leaning Tower of Pisa

The behavior of cultural heritage structures is often investigated or predicted using numerical models. The several parameters defining each model are always affected by uncertainties, and their effects on the outputs should be investigated. In this context, a sensitivity analysis on model parameters provides insight into the dependence of outputs on changes in specific inputs, enabling the selection of the variables that are most suitable for calibration. In the case of modal sensitivity analysis, this approach can also supply useful information for the optimal placement of monitoring sensors. For these purposes, the present paper evaluates the sensitivity of the modal eigenvalues of the model of the Tower of Pisa to the mechanical parameters of the masonry and different layers constituting the underlying soil. This preliminary study allows the detection of modal frequencies that are most influenced by the stiffness of the soil and those purely relying on the masonry, providing guidance for the future model identification based on structural health monitoring data.