# Seismic Isolation Devices for Protecting RC Buildings: The Frangipane School in Reggio Calabria
## 3 The Case Study of Frangipane School
### In-Field Inspection and Experimental Characterization of Materials  
During the preliminary stage of presently reported interventions, a large set of in-field and laboratory experiments has been carried out to characterize the actual mechanical properties of steel and concrete composing the load-bearing frame members, as well as to achieve appropriate knowledge on constructional details, as required by current technical  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Story** & **Pillars [cm]** & **Beams [cm]** \\ \hline F & - & \(50\times 150\) \\ GL & \(50\times 70\) & \(50\times 70\) \\ \(1^{\circ}\) & \(40\times 70\) & \(40\times 70\) \\ \(2^{\circ}\) & \(40\times 70\) & \(30\times 70\) \\ \(3^{\circ}\) & \(30\times 60\) & \(30\times 60\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Cross-section of load-bearing members. F = foundation level; GL = ground level.  
Figure 6: Examples of geometric details for (**a**) columns and (**b**) beams for the Frangipane School (scanned technical drawings), with dimensions in cm).  
standards [31; 32]. The structural analysis and seismic retrofit assumptions were based on a \"Knowledge Level\" (KL, also known as LC) equal to 2 (\"LC2\") of both the structural system and materials properties. Such a result was achieved based on the following:  
* a preliminary historical/archivistic research on documentation about structural details of the system;
* an in-field geometrical inspection of load-bearing features for the building system object of study;
* and an extended set of in-field experimental investigations aimed at capturing the composition of RC members in terms of rebars and stirrups arrangements, but also to quantify the actual mechanical properties of steel and concrete materials.
* Accordingly, the investigation included the following:
* Magnetometric inspections to detect the number, diameter, and position of steel rebars and stirrups (for a total of 100 measurements at various levels of the building). An example is proposed in Figure 7a;
* inspection of the foundation system (Figure 7b);
* inspection of steel rebars in beams and pillars (Figure 7c);
* endoscopic inspection of inter-story floors;
* extraction of samples for concrete and steel mechanical characterization (Figure 7d,e and Table 2).  
Table 2 summarizes the average values of compressive strength for concrete, as obtained from a total of 28 cylindrical specimens (with d/l = 2 the diameter-to-length ratio), which have been extracted from various levels of the building, both for beams and pillars. Experiments on concrete have been carried out according to EN 12504-1 [33].  
Figure 7: In-field experimental investigation (selected examples): (**a**) magnetometric inspection for a pillar; (**b**) foundation system; (**c**) rebars and stirrups of RC members; (**d,e**) concrete and steel rebar samples for mechanical characterization of materials.  
Similarly, the material characterization carried out on 20 samples of steel rebars resulted in an average tensile strength of \(f_{s,y}=371.86\) MPa for yielding and \(f_{s,u}=552.91\) MPa at failure.