Steel Buildings in Europe

Part 7: Fire Engineering 7 - 60 In case of fire, roofs often contribute significantly to fire spread; damage will depend on which structural fire prevention measures were implemented for the roof. Regarding fire propagation in case of a fire from below, then the following failure mechanisms are typical:  The “Durchbrand” burn- through. This is the worst case, with fire spreading on top of the roof, followed by the spread of fire down into other areas through existing roof openings.  Failure of the load-bearing roof shell by slipping from the supports, for example with large spans.  Fire propagation below the roof.  Fire propagation within the roof shell. This is very dangerous because it will not be seen from below. It becomes very critical when the fire services are fighting at the fire source and suddenly it begins to burn behind them. Table A.1 Fire compartment sizes Maximum fire compartment size (m²) Safety category Without fire resistance requirement “R0” With fire resistance requirement R30 K1 Without requirements 1800* 3000 K2 Fire detection 2700* 4500 K3 Rescue service 3200 - 4500* 5400-7500 K4 Fire suppression (Sprinkler system) 10000 10000 * heat extraction area  5% and building width  40m The simplified method is based on the relationship between the permitted surface area of the fire compartment and the safety category, the number of storey and the fire rating classification of the components. The surface area is given in Table A.1 and is well within extreme safety measures. For industrial buildings with an existing sprinkler system (safety category K4), a maximum fire compartment surface area of 10000 m² can be realized without requirements for the fire resistance of structural components. Without any fire protection requirements, surface areas up to 1800 m² can be left unprotected. For industrial buildings which cannot be evaluated using the simplified procedure, the entire verification procedure will be based in accordance with DIN 18230-1.