# Fire Risk Analysis in Large Multi-Compartment Structures Using a Hybrid Multiscale Approach
## 3 Proof of Concept
### Application to a Multi-Story Office Building  
The case study considered is an office building with four floors, labelled A through D, starting at the bottom. Figure 8 displays the plans of the first and second floors of the building, showing the distribution of the compartments, as well as the position and initial state (open or closed) of the doors and windows. The third and fourth floors are identical to the second floor. The building has four emergency exits that are in compartment 07 of each floor. The doors and emergency exits are 2 m \(\times\) 1 m. They are fireproof and therefore do not transmit fire. Each floor has a ceiling height of 3 m and contains 15 compartments: 9 private offices of 5 m \(\times\) 4 m (01 to 04 and 11 to 15), except for floor A, where compartment A04 corresponds to the main entrance; 3 co-working compartments of 5 m \(\times\) 8 m (07 to 09), except for floor A, which has 2 co-working compartments (A07 and A09) and an archive and document storage room (A08, hereafter called archive room); and 3 compartments containing no combustible load, namely the stairwell (06), the elevator shaft (05), and the toilets (10). The 1 m \(\times\) 2 m windows are initially closed, but the glazing can break if the fire in the compartment is fully developed. The exterior walls and floors are made of concrete  
Figure 7: (**a**) Heat release rate of a 70 cm diameter heptane pool fire, and (**b**) distances traveled in time by the isotherms at 180 and 250 \({}^{\circ}\)C.  
and have a thickness of 15 and 10 cm, respectively. They are insulated by a lining combining a plasterboard BA13 that is 1.25 cm thick and a rock wool panel that is 6 cm thick. The inside partitions are made of a 10 cm thick BA13/rock wool/BA13 complex. Two test cases are presented depending on whether the emergency exits are closed or open. For both cases, the fire starts in compartment A08. At this moment, it is assumed that the ventilation is cut off in the whole structure. The building consists of empty (no fuel load) compartments and compartments where a wide variety of combustible materials can be found, such as wooden furniture, computer equipment (e.g., computers, printers), upholstered chains or bernches. To represent this diversity, the fuel in a room is assumed to be a mixture of up to three components: pine wood, a thermoplastic polymer--the poly (methyl methacrylate) or PMMA, and a polyurethane (PU) foam, the distribution and loading of which differ depending on the compartment type. Table 1 gives information on the fuel components present in the three types of compartments and the values of the parameters needed to construct the prescribed HRR time curve in each compartment type using the scaling procedure (see Section 2.2) and the strategy presented in [14] for compartments where multi-fuel combustion occurs. The parameter values are evaluated from tests performed in the DIAMAN device [14] and office building visits. The fire load values are lower than those recommended by EN 1991-2-2 [33]. They match better with localized fires, where only a limited area of the fire load in the compartment is involved in fire. The design fires of the three types of compartments are shown in Figure 9.