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Given weight of wood against same weight of steel have equal strength. Large wood structures do not collapse in temperatures over 600C like steel. Wood is not a

by nosse 14y ago

Given weight of wood against same weight of steel have equal strength. Large wood structures do not collapse in temperatures over 600C like steel. Wood is not as brittle as concrete, which greatly reduces dangers of earthquakes. Problems come from large fires, where wood can act as a fuel. Western world hasn't seen a city burning for a long time and even then it was because of napalm. That might change if wood takes on. Second big problem is moisture, wood can change it's shape greatly with moisture.

ajross 14y ago
> Large wood structures do not collapse in temperatures over 600C like steel Um, no... no, they don't. :) Wood turns into a blackened crust of carbon at about 250C. That is, before it erupts into a tower of flame. It's true that it won't collapse before it will burn. But it will burn long before an equivalent steel structure collapses. But that seems treatable to me. Fire suppression is pretty robust in modern buildings. I think this is great too. But... not at 600C.
- nosse 14y ago
  The point is that in typical apartment fire, the temperature rises to at least to 800C. Steel has good thermal conductivity, and therefore steel structures start to bend greatly when temperature hits 600C in a single floor. This usually causes a collapse. It's very important to quickly evacuate steel building if it's on fire. With massive wood structures the situation is different. The wood is very good heat insulator, so if the skin gets to 1000C the inside might still be lot less than 250C. Wood doesn't burn that quickly as it has to evaporate first (we usually call this smoke) before it can burn. Of course this is all dependent of scale. If you try this out at your fireplace with something that fit's there, the story is completely different. My info comes from Helsinki university of technology construction material lectures. So I can't really paste sources here.
  - nosse 14y ago
    I really don't get the down-voting here. Did I say something that is no true?

by nosse 14y ago

ajross 14y ago

> Large wood structures do not collapse in temperatures over 600C like steel Um, no... no, they don't. :) Wood turns into a blackened crust of carbon at about 250C. That is, before it erupts into a tower of flame. It's true that it won't collapse before it will burn. But it will burn long before an equivalent steel structure collapses. But that seems treatable to me. Fire suppression is pretty robust in modern buildings. I think this is great too. But... not at 600C.

nosse 14y ago
The point is that in typical apartment fire, the temperature rises to at least to 800C. Steel has good thermal conductivity, and therefore steel structures start to bend greatly when temperature hits 600C in a single floor. This usually causes a collapse. It's very important to quickly evacuate steel building if it's on fire. With massive wood structures the situation is different. The wood is very good heat insulator, so if the skin gets to 1000C the inside might still be lot less than 250C. Wood doesn't burn that quickly as it has to evaporate first (we usually call this smoke) before it can burn. Of course this is all dependent of scale. If you try this out at your fireplace with something that fit's there, the story is completely different. My info comes from Helsinki university of technology construction material lectures. So I can't really paste sources here.
- nosse 14y ago
  I really don't get the down-voting here. Did I say something that is no true?