Design of flow and holding capacity of escape routes in buildings
2013
Leur, P.H.E. van de, Ghent Univ. (Belgium) | Scholten, N.P.M., Expertcentre Regulations in Building, Delft (Netherlands)
A method was developed to dimension escape routes in a multi-storey building, controlling both the flow capacity of egress elements and the holding capacity of floor sections. The method is an extension of a current more traditional approach that requires the staircases in a building to provide sufficient holding capacity on each storey to accommodate all occupants of the storey. The width of stairs and doors is governed by the requirement that the building can be evacuated in 15 minutes. The existing method, mandatory in the Netherlands for office buildings, is unsuitable for high density occupancies such as assembly and education. The new method recognizes the protection offered by smoke and fire compartments on the same floor as where the fire originated. It allows using these other compartments to hold occupants for a limited time before they can move into the staircases, thus making the method practicable for high occupant density buildings. A side benefit of the new method is that it forces the designer to consider the likely exit routes taken by escaping groups depending on the location of a fire, not only in the originating fire compartment but in all other parts of the building as well. This is valid not only for the average distribution of occupants over the various parts of the building, but also for any other foreseeable distribution of occupants. The new method was published in 2011 as a Dutch Standard NEN 6089, and was introduced in a modified form in the Dutch Building Decree in April 2012. The paper describes the method, and compares it to popular methods in current use worldwide. The authors argue that the new method overcomes some relevant limitations of the conventional methods, while remaining simple enough to be acceptable as a mandatory analysis for a building permit.
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