# SimEx: A Tool for the Rapid Evaluation of the Effects of Explosions
## 3 Example of Application: Facade of a Building under Blast Loading
### Incident Load  
As previously discussed, SimEx allows the user to enter directly the desired CW-S combination to define the incident blast load. Figure 2 shows the results corresponding to the reference conditions (Level 1, Case 2). For a more detailed analysis of the load induced by the blast wave, the \"Blast Wave\" calculation assistant shown in Figure 10 allows a fast evaluation of all blast parameters as a function of the standoff distance. To this end, the user must provide the following input data: the ground distance from the explosion to the point of calculation, \(d\), the elevation of the explosive charge, \(h_{c}\), and the elevation of the calculation point, \(h_{0}\), both measured from the ground. For \(h_{c}=0\), a hemispherical surface burst computed from Kingery and Bulmash parameters for TNT [18] is considered, although other correlations for hemispherical explosions [1] could also be selected. For \(h_{c}>0\), hemispherical or spherical blasts are both available, letting the user decide what is the best option based on the height of burst. The code does not include correlations for more complex configurations, such as air bursts producing regions of regular and Mach reflections that eventually modify the incident shock wave. The user must also introduce the angle formed by the normal to the structural element at the point of calculation with the horizontal projection of the line joining the center of the explosion with that point, \(\delta\), which is identically zero in our case studies if we assume a symmetric configuration with a pillar in the center of the front facade. These distances and angles are employed for simplicity in obtaining in-field measurements. \begin{table}
\begin{tabular}{c c c c} \hline
**Variables** & **Case 1** & **Case 2** & **Case 3** \\ \hline \(d\) (m) & 12 & 20 & 25 \\ \hline \(W\) (kg) & 30 & 150 & 300 \\ \hline \(Z\) (m/kg\({}^{1/3}\)) & 3.86 & 3.76 & 3.73 \\ \hline \end{tabular}
\end{table} 
Table 4: Standoff distance, \(d\), explosive charge, \(W\), and scaled distance, \(Z\), of the different case studies. The reference case is shown in blue. Figure 9: Schematic diagram of the three-story building under study, composed of equally spaced pillars and an outer enclosure wall, including: (**a**) the distances and angles used for the different floor levels (\(i=0\), \(1\), and \(2\)), including the standoff distance, \(d\), the real distance to the midpoint of the different levels, \(d_{\text{real},i}\), and the corresponding angles of incidence, \(\delta_{\text{real},i}\); (**b**) schematic of the facade constructive details and dimensions; and (**c**) diagram of the equivalent facade element used in the SDOF analysis. L\({}_{i}\) denotes the height of Level \(i\), representing the length of the pillars, and \(S\) is the spacing between pillars, representing the tributary loaded width. With these data, the wizard is able to compute the real distance and incidence angle, thereby providing the peak overpressure, \(p^{\circ}\), the impulse per unit area, \(I/A\), the duration of the positive phase, \(t_{d}\), the blast arrival time, \(t_{a}\), the average speed of the pressure front, \(\sigma=d_{\text{real}}/t_{a}\), the positive phase length, \(L_{w}\), and the waveform parameter, \(\alpha\). The results are presented in a table for several standoff distances, \(d\), which also gives the real distances, \(d_{\text{real}}\), and angles of incidence, \(\delta_{\text{real}}\). The maximum and minimum distances that appear in the table can be easily modified by the user, who can select any intermediate value using a slider bar to compute the blast parameters at a fixed specified distance. A button has also been included to graphically represent the variation of any of the blast parameters as a function of the distance to the center of the explosion. The results are also exportable as a \"comma-separated-value\" format for further postprocessing. For more qualitative information, two exportable graphs are presented in the lower part.