PSI - Issue 64

Luigi Petti et al. / Procedia Structural Integrity 64 (2024) 637–644 Petti L., Lupo C., D’Angelo T., Dallocchio P. & Guizzetti D. / Structural Integrity Procedia 00 (2019) 000 – 000

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With respect to the heritage materials, sensors have been installed with a safety anchor on the protective covers of the capitals. In particular, the devices support bases were fixed onto the protective covers using mortar and mechanical plugs. The bases were then protected laterally with the same mortar, which included pigments to camouflage the support with the travertine. Figure 6 shows one of the installed sensors.

Fig. 5. (a) Inner view of the EST elevation with location of devices. (b) Temple of Athens plan with location of the nodes.

Fig. 6. (a) Positioning of device support on the abacus of the column; (b) Installation of the device on the support; (c) Final configuration.

4. Data Analysis and Preliminary Results The correct interpretation of data requires detailed analysis to extract useful information that may be hidden within the signal. In fact, recorded data are strongly influenced by the environment conditions, the weather and the characteristics of the devices used to collect them, see Han Q. et al (2021), Ribeiro R. R. and Lameiras R. D. M. (2019). Therefore, ad-hoc data elaborations are necessary to develop. The first approach to the analysis of monitoring data is based on a critical judgment of the data trend. A significant deviation from the typical trend is often a first indicator of the development of a phenomenon. However, this difference could be caused by a change in the boundary conditions during the measurement. In an outdoor monitoring context, the weather conditions, and in particular temperature, rain, and wind, have a significant impact on measurements. Their influence is obviously different depending on the device in use and the type of monitored phenomena, see Baessler M. et al. (2019). Temperature variation, for examples, directly affects the structural response. An increase or decrease in temperature causes expansion or reduction of the material, which may occur at different times than environmental thermal variations due to the thermal inertia of the materials and structures. Rain and wind may affect in different ways. For example, in the case of the Temple of Athena, they can cause the movement of material on the ground or the formation of puddles, which can modify the reading surface of the laser, as well as the temperature itself. In the case of the Temple of Athena, the adopted strategy of data analysis involves different approaches concerning: • An expert judgement of data trends; • Statistical analysis to evaluate the recorded phenomena from a qualitative and quantitative point of view; • Correlation analysis to assess the affinity of the measurements variations with other phenomena not directly attributable to structural aspects; • Signal Processing based on Fourier Theory to filter the raw signal and to focus attention only on its relevant components.