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Yea, I went looking for the same thing. I find it misleading to claim that steel melts in high rise fires and collapses (only three times in history) but wood c
by stmfreak 8y ago
Yea, I went looking for the same thing. I find it misleading to claim that steel melts in high rise fires and collapses (only three times in history) but wood chars and becomes fire resistant (at same temperature to melt steel??).
I would never choose to live or work in a multi-Tennant hi-rise due to fire risk.
- aaronblohowiak 8y agoYou don’t have to get anywhere near melting temp to weaken the beam strength of steel. From the internet: Average building fires reach temperatures of 700 to 1000°C. Steel weakens dramatically as its temperature climbs above 230°C, retaining only 10 percent of its strength at 750°C. Wood generally does not ignite until it reaches 250°C. Once it catches fire, wood develops a protective insulating char layer. After 30 minutes a large wooden beam will have lost around 25 percent of its strength in a 750°C fire and retain structural integrity – a steel beam will have lost 90 percent strength and will have failed.
- umvi 8y agoBut what is actually burning in a steel and concrete structure? Drywall and carpet?
- burfog 8y agoUsually nothing, because this pretty much doesn't happen. It is nearly correct to say that steel buildings never burn down. The last exception to this rule involved luggage, seats, and lots of jet fuel.
- macawfish 8y agoSome guesses: furniture, bedding, appliances, clothes, papers, trim, flooring, paint, etc.
- sundvor 8y agoCombustible cladding. https://www.theage.com.au/politics/victoria/smoke-alarm-warning-with-no-sign-of-fix-to-melbourne-s-cladding-crisis-20190215-p50y6j.html https://www.theage.com.au/politics/victoria/smoke-alarm-warn... https://www.theguardian.com/uk-news/2018/jun/18/fire-safety-rules-rely-solely-on-staying-put-grenfell-inquiry-ladders https://www.theguardian.com/uk-news/2018/jun/18/fire-safety-...
- kosievdmerwe 8y agoI'm speculating, but steel takes up less space for the same strength, so you can use that extra space for fireproofing/insulation. How would this affect the calculus?
- themmes 8y agoAbsolutely! Its a matter of dimensions, for wood we simply oversize a few centimeters to burn through to make sure it holds long enough to get out of the building. I assume this indeed takes more space than a fire insulated steel beam. The achievement here is the Norsk got over the medieval fear of burning houses and can now use their loved local wood to tackle urban densification challenges!
- aaronblohowiak 8y agoWood can be very very low carbon compared to concrete as a building material because the wood itself is a carbon sink.