3 ms·
wood is far more safer when exposed to heat than metal. while wood starts to burn on the outside it turns into coal, which effectively seals the remaining wood
by pinaceae 16y ago
wood is far more safer when exposed to heat than metal. while wood starts to burn on the outside it turns into coal, which effectively seals the remaining wood core from oxygen - preventing (for a while) further structural loss. this is taken into consideration when sizing wooden structures in buildings.
metal on the other hand loses structural integrity when exposed to heat shockingly fast. the wtc towers showcased this effect quite publicly.
experienced firefighters prefer to deal with fire in wooden structures than in metal ones. they can predict how long a wooden roof structure will take till collapse quite well, while a metal structure is a nightmare.
so, flammability and structural integrity under heat are two different things. non-intuitive for most non-engineers, hence the retarded wtc discussions.
in SF's case they use wood because of its function as an isolator.
- MichaelApproved 16y ago>>metal on the other hand loses structural integrity when exposed to heat shockingly fast. the wtc towers showcased this effect quite publicly. but isn't that at extremely high temperature? Wouldn't that same amount of heat burn wood far faster than it would damage metal? The wtc towers were exposed to jet fuel and beaten by a jetliner slamming into the building. Also, the metal beams in the wtc towers were made of steel while ladders are made of aluminum.
- evgen 16y agoFor a straight-up failure test, yes. Try exposing wood and metal to fire, then cool it, then expose it again, etc. You can tell visually when the wood is likely to fail much easier than the metal.
- sokoloff 16y agoAluminum (in most alloys) loses significant strength in the 400-500*F range. By 600F, Al alloys are very weak. http://www.burnsstainless.com/yieldstrength.aspx http://www.burnsstainless.com/yieldstrength.aspx
- baguasquirrel 16y agoAluminium also melts before it glows red from being hot. It's why it's relatively difficult to weld, and why there were a lot of failures in early aluminum-frame bikes.
- damoncali 16y agoIf a metal ladder gets hot enough to fail structurally, there are far bigger problems afoot.