Like maybe cause a building collapse or roadway?

http://www.komotv.com/news/7247236.html

A state engineer says some, but not all, roads in the state of Washington may be able to survive a spectacular calamity like the one that melted a section of a vital roadway in Oakland, California.

Flames from an overturned gasoline tanker were so intense that a part of the freeway melted and crashed onto itself in Oakland on Sunday. The truck was carrying 8,600 gallons of gas when it exploded at a major interchange that funnels traffic off the San Francisco Bay bridge.

The ball of fire mangled the road known as the 'MacArthur Maze', twisting every steel beam inside and crushing the concrete outside.

Jugesh Kapur, a state engineer with the Department of Transportation, says the collapse in California is a real possibility here in Seattle.

"It could happen anywhere," he said. "One road isn't any more vulnerable than another one."

Four years ago, a tanker truck exploded on Interstate-5, shooting flames 100 feet high up in the air near Lynnwood. The truck was carrying more gas than the one that exploded in Oakland, but Kapur says the road survived in part because it wasn't made of steel.

"Washington is mainly concrete country. 80 percent of our bridges are made of concrete," he said.

Kapur says concrete is cheaper in Washington state and it's also more reliable. Concrete can withstand three- to four times more heat than steel, and State Route 509 is proof.

Five years ago, a rail car carrying chemicals exploded beneath SR 509 and burned at 1,700 degrees.

"We had extensive damage, but it didn't come crashing to the ground," Kapur said.

But not all of the state's roads are as strong. The east channel bridge to Mercer Island is made of steel, as is 20 percent of the state's roads.

It's not possible for burning hydrocarbon fuel to melt steel simply because the temperature of the fire (1500 F.) is well below the melting point of the steel (2750 F.).

But, it's certainly possible, and likely, that the fire will cause the steel to expand significantly and weaken at the higher temperatures resulting in the lack of capability to support the load of the concrete.

I thought we were moving back in the 9/11 debate.
Brian must be on the side of the skeptics.

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Not at all.

Note that the capability of the steel to support the load is reduced dramatically with the higher temperature. It doesn't need to melt, in the traditional sense, to buckle and fail due to the heat.

None of the steel melted in the WTC collapse. But, it was certainly twisted up quite a bit.......even before it took a 1000 foot ride.

Stupid bolts.

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Gas doesn't explode, it burns at a rate limited by the available oxygen. If you want it to burn faster you have to scatter it to burn in the presence of available oxygen or supply more oxygen to the scene of the burning.

None of those Washington State concrete structures discussed above contain rebar?

I'm sure they all did, but the rebar is very well insulated from the direct heat of the fire by the concrete.

An explosion is just a fast chemical reaction, a burn. Very fast. I'm sure somebody has a taxonomy of explosives based on burn velocity, in fact I believe that is what separates Class A (high explosives) like TNT from Class C like black powder. Is there a Tangas in the house?

can automotive fuel (in a normal air fuel ratio 14:1) melt steel? NO
can it heat steel to the point it cannot support the loads it was designed to support? YES. Exactly why steel framed building are protected with fireproofing material; which delays the time to failure, very different and much earlier than melting.
regards,
Mark

That happend right down I-95 from me in 2004, right after the route 25 connector in Bridgeport, and before I think its exit 24. Some bimbo nailed a fuel truck and it exploded and melted a bridge. The highway was closed for about a week, talk about traffic! Said bimbo is lucky she wasn't shot! At the time I was going down their every day for school, and I remember driving next to the bridge right after it happend, talk about cripsy! The steel was bent badly, the concrete itself looked pretty good.

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The heat causes the steel to move into plastic deformation under load, to the point a connector fails and it falls. Steel deforms before it breaks under normal stress if you push it to the limit of the steel. However, the heat will cause deformation to occur at a lower load than under normal circumstances.

If it melted, you would have a pile of hardened slag, not twisted beams etc..

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Acceleration is one key. An explosion feeds on itself, a burn takes in o2 from the environment. A bursting vessel is an exception to this, it scatters the fuel and exposes it to more oxygen that way.

There is more than one type of explosion. Combustion is one type. It is caused by an oxidation reaction of chemicals (e.g. gunpowder). Another is an explosion due to the rupture of a pressure vessel when the vessel fails.

Two completely different things. But if your pressure vessel contains flammable material, when it mixes with enough O2 for combustion, you can have both types at the same time, well actually one occurs after the other but you won't notice that when running for the hills.

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It wasn't the heat of the flames that brought down the overpass, it was the explosives placed earlier.
Today in the Chron they said that they're going to drill tiny core samples out of the concrete on the lower roadway to determine if the steel was compromised. Also said they would X-ray it.

The crash occurred on the lower roadway, the upper one got the "benefit" of the hear more directly. They're hoping, of course, that the lower roadway is not as severely damaged as the upper so they can get it back into service in a hurry.

I use both overpasses semi-regularly but luckily for me, I'll be able to work around it a lot better than many will. This damn thing was sort of a perfect storm -- the guy crashed just under the overpass.

Said today in the paper the driver has prior convictions for heroin.

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