## 4 Description of the Developed Software
### Methodology for the Estimation of Unknown Input Structural Parameters
Therefore, the structural parameters of the MFPNNs' input vectors (Equation (2)) could be reliably known (measured in situ, obtained by technical reports and drawings, or calculated) or completely unknown. In the first case, the user can directly insert the values of the four required structural parameters. In the second case, the user defines the missing parameters as unknown. Reasonable assumptions (based on the available data (Figure 7)) are necessary for the use of the software developed, since it is based on MFPNNs that require the input of the aforementioned structural parameters (Equation (2)). The parameters that are difficult to estimate, using the available structural input data, are the ratios n\({}_{\text{v1}}\) and n\({}_{\text{v2}}\) and the value of the structural eccentricity e\({}_{0}\). Based on the above, parametric analyses are proposed in order to apply the software developed consistently and reliably, using the external function \"FORM_ANN_INPUT\" (Table 5). The first approximation of n\({}_{\text{v1}}\), n\({}_{\text{v2}}\), and e\({}_{0}\) values, is a reasonable, user-defined value range (i.e., minimum and maximum values). This value range is estimated accounting for the structural data inserted by the users to the corresponding GUI window (Figure 7). Regarding the structural eccentricity e\({}_{0}\), the minimum (mine\({}_{0}\)) and the maximum (max\({}_{0}\)) are defined based on the following two structural data inserted by the user (Figure 7): (a) Regularity (or not) of the building in plan, and (b) Regular (or not) distribution of masonry infills in plans. According to the input of the aforementioned structural parameters, three levels of structural eccentricity are defined, namely low, medium, and high eccentricity. These levels are related to specific value ranges of e\({}_{0}\), as illustrated in Table 6. All values of the structural eccentricities are expressed as a percentage of the buildings' plan dimensions L\({}_{\text{i}}\) (i = 1,2, Figure 14), following the rationale of seismic codes such as EN1998-1 [49]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Case 1** & **Case 2A** & **Case 2B** & **Case 3** \\ \hline
**Regularity in plan** & Yes & Yes & No & No \\
**Regular distribution of masonies** & Yes & No & Yes & No \\
**Eccentricity** & Low & Medium & High \\
**mine\({}_{0}\)/max\({}_{0}\)i** & 0.05L\({}_{\text{i}}\)/0.075L\({}_{\text{i}}\) & 0.075L\({}_{\text{i}}\)/0.15L\({}_{\text{i}}\) & 0.15L\({}_{\text{i}}\)/0.175L\({}_{\text{i}}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Relation assumed between the structural data inserted by the user and the structural eccentricity e\({}_{0}\). Figure 14: Description of the structural parameters imported to the input vectors of the trained MFPNNs. As regards the assumptions for the estimation of the ratios n\({}_{\rm v1}\) and n\({}_{\rm v2}\), the following three structural data inserted by the user (Figure 7) are considered: (a) The existence (or not) of RC shear walls along the two horizontal directions (axes) x(\(\equiv\)1), y(\(\equiv\)2) if this information is reliably known, (b) the year or the period of the building's construction, and (c) the application (or not) of seismic code provisions for the design of the building. All the structural data described above are considered to define the maximum and the minimum values of n\({}_{\rm v1}\) and n\({}_{\rm v2}\). In the current version of the software application, the limit values of n\({}_{\rm v1}\) and n\({}_{\rm v2}\) were estimated considering the construction practices followed in Greece. However, an expansion of the software source code in order to cover different limit values for n\({}_{\rm v1}\) and n\({}_{\rm v2}\) is relatively easy.