Atlanta I-85 Freeway Fire and Collapse - World Trade Center Comparisons

benthamitemetric

Senior Member
A fire caused a major failure of a highway overpass today in Atlanta, adding to the already-extensive record of fire induced collapses of substantial structures:

http://www.usatoday.com/story/news/.../interstate-85-massive-fire-atlanta/99849834/

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The fire chief speaks of spalling concrete.

Obviously, these fire professionals did not think that "black smoke" means "cold fire - no danger of collapse".
 
Great photos, Mick. Thanks. At least for me, it's a solid reminder at how ill-adapted the human mind is to imagining how complex fire scenarios can unfold. I wouldn't have supposed by looking at them that those spools could have resulted in such a large and intense fire. My first thought when looking at the fire was that there must have been some sort of tanker accident or some accident involving something like stored gasoline or kerosene. Easy to forget that there can be just as much (if not more) energy in more mundane, non-volatile items.
 
A fire caused a major failure of a highway overpass today in Atlanta, adding to the already-extensive record of fire induced collapses of steel framed structures:

I really don't think you can describe this as "steel framed". Steel framed implies steel columns and girders. The thing that failed here seems just have been a steel-reinforced concrete slab over steel reinforced concrete bridge beams and columns, like:
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Not like:
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Perhaps you should edit your first post.
 
I really don't think you can describe this as "steel framed". Steel framed implies steel columns and girders. The thing that failed here seems just have been a steel-reinforced concrete slab over steel reinforced concrete bridge beams and columns, like:

...

Perhaps you should edit your first post.

Agreed. My first post is incorrect as I had assumed the girders than ran lengthwise below the highway sections were steel encased in concrete, but it appears they are more likely steel reinforced concrete as you note. I can't directly edit the first post any longer, but I would change "steel framed" to simply be "substantial".
 
Agreed. My first post is incorrect as I had assumed the girders than ran lengthwise below the highway sections were steel encased in concrete, but it appears they are more likely steel reinforced concrete as you note. I can't directly edit the first post any longer, but I would change "steel framed" to simply be "substantial".
I've edited it for you.
 
Hey everyone. First post. Will post over in the intro later. This is The first thread I knew something about with reasonable certainty.

The concrete girders are likely pre-stressed concrete, with tensioned cables inside. Once the heat starts to spall the concrete or the cables get hot enough to loose strength, the girders will fail. Each cable had upwards of 25,000 pounds of tension on it, depending on it's diameter.
 
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