# Fire Risk Analysis in Large Multi-Compartment Structures Using a Hybrid Multiscale Approach
## 3 Proof of Concept
### Application to a Multi-Story Office Building
#### 3.1.2 Network Model Results  
The network model was applied to two different fire scenarios. In average, a run takes a few CPU seconds on a 3.40 GHz/16 GB RAM PC. _First fire scenario_  
For this fire scenario, the emergency exits are closed. Table 4 and Figure 11 show the chronology of the fire, where the origin of the time corresponds to the ignition of compartment A08. First, the fire spreads both through both openings (e.g., from A08 to A04) and exterior windows (e.g., from A01 to B01). The compartment of fire origin A08 reaches the flashover after \(18^{\prime}\) of fire. Compartments A04, A07, and A09, which are connected to it by an open door, also ignite within one minute. After reaching the flashover, these compartments spread the fire to the remaining compartments on the second floor (A01, A02, A11, A14, and A15). After \(27^{\prime}\) of fire, all the sensitive compartments on floor A with at least one open door ignite. They experience a fully developed fire \(6^{\prime}\) later. As soon  
Figure 10: Time evolution of (**a**) mass flow rate, and (**b**) temperature and density of the smoke leaving the archive room. as the flashover occurs in A09 (at 27\({}^{\prime}\)), all conditions are met for the fire to spread from the outside of the building to compartment B09 on the second floor. Seven minutes later (at 34\({}^{\prime}\)), the same phenomenon allows for the fire transmission to compartments B01, B02, B11, B14, and B15. Out of the six affected compartments on floor B, none of them reaches flashover. In 34\({}^{\prime}\), the fire spread to 15 rooms on the first two floors of the building. Of these 15 rooms, 9 reach the flashover. After 63\({}^{\prime}\), the fire is extinguished. Figure 12 shows how smoke fills the building over time. The smoke first spreads horizontally through floor A, filling the compartments adjacent to the fire source compartment (A07, A09, and A04), and then the neighboring compartments (A01, A02, A14, and A15), after 6\({}^{\prime}\) and 10\({}^{\prime}\) of fire, respectively. The smoke then reaches the upper floors through the stairwell and simultaneously fills compartments 09 of floors B to D in 15\({}^{\prime}\), then compartments 13 and 14 in 17\({}^{\prime}\). From 21\({}^{\prime}\) onwards, compartments A04, A07, and A08 ignite and the smoke they generate is added to that of compartment A08. Compartments 03, 04, 11, and 12 are filled with smoke after 25\({}^{\prime}\), co-working spaces 08 after 32\({}^{\prime}\), and finally private offices 01, 02, and 11 after 36\({}^{\prime}\). In 36\({}^{\prime}\), the smoke fills the entire available space, i.e., 49 rooms on the four floors. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Compartment Number**} & \multirow{2}{*}{**Floor**} & \multicolumn{3}{c}{**Time (min)**} \\ \cline{3-5}  & & **Ignition** & **Flashover** & **Extinguishment** \\ \hline A08 & 1 & 0 & 18 & 25 \\ A04 & 1 & 19 & 25 & 28 \\ A07 & 1 & 19 & 26 & 29 \\ A09 & 1 & 19 & 27 & 29 \\ A01 & 1 & 27 & 33 & 36 \\ A02 & 1 & 27 & 33 & 36 \\ A11 & 1 & 27 & 33 & 36 \\ A14 & 1 & 27 & 33 & 36 \\ A15 & 1 & 27 & 33 & 36 \\ B09 & 2 & 27 & - & 55 \\ B01 & 2 & 34 & - & 63 \\ B02 & 2 & 34 & - & 63 \\ B11 & 2 & 34 & - & 63 \\ B14 & 2 & 34 & - & 63 \\ B15 & 2 & 34 & - & 63 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Fire chronology for the first fire scenario in the four-story building. Figure 11: First fire scenario in the four-story building: fire maps predicted by the network model after 19\({}^{\prime}\), 27\({}^{\prime}\), 34\({}^{\prime}\), and 63\({}^{\prime}\) of fire. Color code: orange: ignited compartments; yellow: compartments where the fire was transmitted through an exterior window; red: compartments where fire is fully developed; gray: compartments where fire is extinguished. In order to evaluate the reliability of the results obtained with the simple smoke filling model, the transport of smoke was also simulated using the 3D CFD software SAFIR, validated for many fire scenarios (see for example [10]).