Citat:
Ursprungligen postat av
locknloll
Det är egentligen helt vansinnigt att ett helt höghus kan brinna till den milda grad att bara ett tomt skal blir kvar. Dessutom Stegar som inte räcker och vatten som inte kan sprutas tillräckligt högt.
Människor som hoppar utan att kunna landa mjukt.
Man skulle kunna tro att detta var mänsklighetens första höghus, byggt i trä.
Vi kan resa till månen men inte ens spruta vatten från luften.
Det skall egentligen inte behövas om designen på huset är bra nog.
Citat:
When designing the building, a certain timeline of the fire is assumed. A fire starts and develops in one room, then spreads. Q (energy release) = 0 at t (time) = 0, following a standardized Q-t curve from there on. Steep or shallow, that depends on the material and the shape of the room. When Q reaches a critical value, let's call it Q_crit, the fire will spread through the walls of the room. The job of the designer is to pick materials and solutions so that the time of penetration (t_crit) is larger than a required time t_req. t_req is assumed to be the time the fire department needs to be warned about the fire, get to the blaze, and put it out while Q < Q_crit. That is, the fire should be put out before it spreads out of its initial room.
Failing that, t_req should at least be large enough to warn all the residents and evacuate them out of the building. So in practise, there should be time to get everybody out of the building before the fire leaves the room it started in.
So far, so good. If these practises are adhered to, everything is peachy. But imagine that a door that should be self-closing is propped open, or that the height of a fire safety wall only extends to the dropped ceiling instead of the floorplate above. Suddenly, you have fire penetration at t = 1 min, instead of, say, t = 45 min. Now you have the Q-t curve developing in two adjacent rooms instead, and the opening allows them to feed one another from each other's heat release, accelerating both fires.
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