Determining structural models of a masonry tower from Architectural research and operational modal analysis

The paper presents a fully non-destructive methodology, aimed at defining appropriate structural models of ancient towers by integrating Architectural Research with Operational Modal Analysis (OMA). The outlined approach includes the following steps: (i) documentary research, detailed visual inspection and geometric survey; (ii) simplified vibration testing, involving the measurement of the response to ambient excitation only at the top of the building; (iii) Finite Element (FE) modelling; (iv) definition and updating of the uncertain parameters of the model (that is performed with the possibility of iteratively integrating qualitative data from Architectural Research). The methodology is exemplified on the ancient Zuccaro tower in Mantua (Italy), where two FE models − a simplified beam model and a refined 3D solid model − were developed and updated using the dynamic characteristics extracted from output-only modal tests. Both models achieved high accuracy in representing not only the identified natural frequencies but also the available mechanical characterization of the materials (which was used only for verification purposes). Moreover, the crucial role of Architectural Research is highlighted in detecting and modelling the different masonry regions as well as the stiffening effects of timber floors.