Behavior of steel framed structures under fire conditions.

Since people think they know everything about how steel framed structures act in fires. Here's something to chew on. A study pre-9/11 that shows conclusively that it has no affect on them. The biggest affect is the elongation due to the heat. NOT strength reduction. Fire-proofing or not.

DEBUNK THIS!!!!!!!!!!!!!!!!!!!

guardian.150m.com...

Edit: Sorry for all caps in thread title.


[edit on 8/15/2007 by Griff]

six full-scale fire tests on a real composite frame structure at Cardington showed that despite large deflections of structural members affected by fire, runaway type failures did not occur in real frame structures when subjected to realistic fires in a variety of compartments.

First paragraph.

Of the identified phenomena, the dominant effect is that of restrained thermal expansion in the main structural elements. In the early stages of the fire, lateral restraint to translation (causing compression), coupled with rotational restraint to thermal bowing (causing hogging moments), leads to local buckling in the steel beams which limits the forces applied to the rest of the structure and to increasing deflections in a post-buckled state.

Part of the conclusion.


[edit on 8/15/2007 by Griff]

[edit on 8/15/2007 by Griff]

No responses, of course!


They study also found that buckling and warping failures don't occur from strength loss due to heat transfer, but from stresses induced from thermal expansion.

In other words, when steel gets hot and expands, this is the primary mechanism for warping and buckling in steel columns heated to 600 C or less. Not strength loss, due to the steel getting soft like spaghetti noodles, as some suggest.

If somebody does respond they will simply state that in this study no airplane hit the frames being testing. Of course, silly us, when an airplane hits all bets are off.

Steel Frame -> Airplane Hits -> then some Magic -> Steel loses 100% of its strength.

I thought this was common knowledge?

Doh!

Considering that 40-60% of the American population actually believes that Jesus will return within their life time, it seems rather futile to convince people that an airplane hitting the WTC towers does not automatically mean it was destined to collapse like the media has seemingly convinced people.

Good stuff, Griff.

Lurker - I hope for the return of Christ during my lifetime but apparently my spiritual beliefs have not affected my ability to think. You seem to have some type of flaw in your logic there.

Originally posted by Valhall
Good stuff, Griff.

Credit goes to BsBray for finding this gem.

I hope for the return of Christ during my lifetime

Would be nice.

Originally posted by Valhall
Good stuff, Griff.

Lurker - I hope for the return of Christ during my lifetime but apparently my spiritual beliefs have not affected my ability to think. You seem to have some type of flaw in your logic there.

Hmm, odd.

Although I find it ironic that a Christ believer points out flaws in my logic I'll have to withdraw my point and concede that the two are not necessarily connected.

Quote from article "The common assumption in structural fire resistance design is that fires will be localised through effective compartmentation. In the absence of this assumption, it becomes very difficult to predict the behaviour of the structure because the fire behaviour in such cases is very uncertain, therefore the heating regime and sequence in the structure is unknown."

Localised does not mean an entire group of floors.

This is one of many quotes i could use to differentiate between the meaning of this article and what you are using it for. This was not designed to debunk or shead new light on the Towers collapse. This is more of a study to further thier own understanding of steel. There is also a big difference in what is discussed in this as its more of how can we imrove things. I have worked for a few steel related companies managing their risk departments. There is a huge difference between old steel and new steel. Old steel is much more brittle than new steel and the towers were made with what would be considered old steel. I am not in the business of debunking anyone's theories, but I am willing to shed light on some things that I have an understanding of.

If you want to learn more about steel try this web page:

www.key-to-steel.com...

There are alot of free article you might find interesting. Form the history of steel making to how the slightest impurities in steel (residual elements) can cause a profound effect on their mechanical properties.

Have a good day.

Originally posted by traderonwallst
This was not designed to debunk or shead new light on the Towers collapse.

That's because it was pre 9/11.

My point exactly.

So are you saying that the towers were made with old (brittle) steel? I'm confused.

No I am not outright saying that. As the steel used was never comletely tested and according to "findings" would have been of no use if they were. The composite of the steel changed due to the heat of the flames. We do not mine for steel. All steel is maed in a furnace from other molten metals, and additives. Nickel is one used to strengthen steel. Many other elements are now used also.

What I am saying is the current steel is many times better for erecting sky reaching buildings than the steel used in the construction of the Towers. I am not saying the steel was brittle. I am blaming no one.

I am just saying, new steel might not have allowed the "pancake" like implosion.

The very study we're talking about says the alloy of steel makes negligible difference across the board, as long as it's up to code, and hydrocarbon fires won't change the chemistry of up-to-code (ASTM) steel, because they don't get that hot. In fact, anything even remotely resembling steel in chemical make-up, or that can be considered steel even by loose standards, even iron, is not going to fail from a fire that itself can't get much hotter than 700 C around the flames themselves.


Specifically, the study says on page 54 (or 61 of the PDF):

The temperature dependent stress-strain properties of concrete and steel were taken from EC2 [3] and EC3 [2] respectively. As discussed earlier the effect of steel stress-strain properties is very limited and the results are not sensitive to minor variations in these.

www.studyof911.com...

Originally posted by traderonwallst
Quote from article "The common assumption in structural fire resistance design is that fires will be localised through effective compartmentation. In the absence of this assumption, it becomes very difficult to predict the behaviour of the structure because the fire behaviour in such cases is very uncertain, therefore the heating regime and sequence in the structure is unknown."

Yes, and that's one reason they did these tests and released this study in the first place.

The very next paragraph after the one you quote starts off like this:

A prime objective of the tests conducted at Cardington on the BRE eight-storey frame was to provide data to aid the development of understanding of the interactions between different structural mechanisms which determine the overall behaviour of composite steel frames in fire.

And then they go on:

In order to formulate general recommendations for steel framed structures in fire it was essential to develop a reliable model, which could extend the database of test results to different structural forms and configurations together with a consideration of various fire scenarios.

This is one of many quotes i could use to differentiate between the meaning of this article and what you are using it for.

Well keep posting them because I don't think you've hit anything so far.

[edit on 16-8-2007 by bsbray11]

Did they use JET FUEL as one of their accelerators for the fire????





Well.........Did they???? A jet fuel fire can, does and did at much higher temperatures.

Originally posted by traderonwallst
Well.........Did they???? A jet fuel fire can, does and did at much higher temperatures.

Jet fuel doesn't burn at any higher of a temperature than paper.

It is an accelerant, but that just means it burns fast. Even NIST agrees that most of it was gone, burnt up, in the first 10-15 minutes of fire in either building.

Originally posted by traderonwallst
Did they use JET FUEL as one of their accelerators for the fire????

Well.........Did they???? A jet fuel fire can, does and did at much higher temperatures.

What jet fuel? Most of the jet fuel was burned off in the intial explosion. What was left burned off quickly according to both NIST and FEMA reports.

Originally posted by traderonwallst
Did they use JET FUEL as one of their accelerators for the fire????

Well.........Did they???? A jet fuel fire can, does and did at much higher temperatures.

Well if jet fuel is your reasoning for accelerating the fire to bring down the buildings,then can you explain WTC 7,which had no jet fuel to effect the fire.But yet the building came down.

WTC 7 - sure:



www.abovetopsecret.com...'

Originally posted by ULTIMA1


What jet fuel? Most of the jet fuel was burned off in the intial explosion. What was left burned off quickly according to both NIST and FEMA reports.

Exactly, they specifically state this.

Valhall.

Do you have that information about eyewitnesses experiencing explosions and fires on the mechanical floors anymore? I just started a database (finally) of all the things. Thanks in advance.